Application Note - Freescale Semiconductor
Contents
1. A transition to RESET state is performed by setting the event to event e_reset which is done automatically when the user sets switchAppReset to true using FreeMASTER A transition to FAULT state is performed automatically when a fault occurs A transition to INIT state is performed by setting the event to event e_app_off which is done automatically on falling edge of switchAppOnOff false using FreeMASTER 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 20 Freescale Semiconductor Inc Software design MPC5604P PMSM FOC procon We uAlBeRegDCB s32Arg2 x pwm32 s32Argl idQReq s32Argl iDQReqZC s32Argl iDQErr s32Arg1 uDQReq s32Argl uAlBeReq s32Argl pwm32 s32Argl iDdQReq s32Arg2 iDQRegZC s32Arg2 iDQErr s32Arg2 uDQReq s32Arg2 uAlBeReq s32Arg2 A pwm32 s32Argl v 1 r3 y GDFLIB_FilterlIR 1 dAxisZC GDFLIB_FilterlIR4 Q qAxisZC li wRotElReq wRotElErr AT sae See alll lt anna gt 1 amp E lt amp i H Bj iAbeFbck s32Argl iALBeFbck s32Argl iAbcFbck s32Arg2 wRotElRegRanp iAlBeFbek s32Arg2 iAbeFbek s32Are3 Lee ti r iDQFbck s32Argl ts 3 phase i current reconstruction t ADC_Measure2Ph iDQFbck s32Arg2 NM thRotElSyst s32Argl Fast Current Loop thRotl syst s32arg2 100us POSPE_GetSpeedElEnc zes Speed Loop POSPE_GetSpeedElRes ms Figure 12 Variables and functions as implemented in F2. Freescale Semiconductor Document Number AN4561 Application Note Rev 1 11 2015 3 Phase PMSM Motor Control Kit with the MPC5604P by Roman Filka and Marek Stulrajter Contents 1 Introduction T ifs gc isis ts eemremnrerene tremens emer emene rte ar err art are 1 SEV STS CONCE E E E 1 PMSM treld oriented controles scesssctcentsaesasions 2 MPC5604P CB configuration eese 7 This application note describes the design of a 3 phase Permanent Magnet Synchronous Motor PMSM vector control drive with 3 shunt current sensing with a position sensor The design is targeted for automotive applications This cost effective solution benefits from a Freescale Semiconductor MPC5604P device dedicated for motor control SPE WS SO 1 sacessidesdnisiaisevasadaranticiemamntoereiaielanes 13 Application control user interface eee 23 The system is designed to drive a 3 phase PM synchronous Ree E E arid ENT 26 motor Application features e 3 phase PMSM speed Field Oriented Control e Current sensing with three shunt resistors e Support for encoder and resolver position transducers e Application control user interface using FreeMASTER debugging tool e Motor Control Application Tuning MCAT tool o u A a A N Revision MSto cenieni 26 2 System concept The system is designed to drive a 3 phase PM synchronous motor The application meets the following performance specifications e Targeted at the MPC5604P Controller refer to dedicated
3. 2 Phase _ Rotating _4 a Stationary Phase C_ 3 Phase System 2 Phase System 3 Phase System Rotating Reference Frame Figure 1 Field oriented control transformations 3 2 PMSM model in quadrature phase synchronous reference frame Quadrature phase model in synchronous reference frame is very popular for field oriented control structures because both controllable quantities current and voltage are DC values This allows to employ only simple controllers to force the machine currents into the defined states Furthermore full decoupling of the machine flux and torque can be achieved which allows dynamic torque speed and position control The equations describing voltages in the three phase windings of a permanent magnet synchronous machine can be written in matrix form as follows 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc 3 PMSM field oriented control uy i4 Va ug Rip 4 Wp uc ic Wo Equation 2 Three phase voltage model of AC motor where the total linkage flux in each phase is given as Wa La Ly Daly cos Yg Loa Loo Loclia ypy cosl 2x 3 Yel Eca L Leckic cose 27 3 Equation 3 PMSM total linkage flux matrix where Laa Lbb Lec are stator phase self inductances and L Lp Lbe Leb Lea Lac are mutual inductance between respective stator phases The term Ypy represents the magnetic flux generated by the rotor permanent magn
4. Power Information in this document is provided solely to enable system and software implementers to use Freescale products There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits based on the information in this document Freescale reserves the right to make changes without further notice to any products herein Freescale makes no warranty representation or guarantee regarding the suitability of its products for any particular purpose nor does Freescale assume any liability arising out of the application or use of any product or circuit and specifically disclaims any and all liability including without limitation consequential or incidental damages Typical parameters that may be provided in Freescale data sheets and or specifications can and do vary in different applications and actual performance may vary over time All operating parameters including typicals must be validated for each customer application by customer s technical experts Freescale does not convey any license under its patent rights nor the rights of others Freescale sells products pursuant to standard terms and conditions of sale which can be found at the following address freescale com SalesTermsandConditions Freescale and the Freescale logo are trademarks of Freescale Semiconductor Inc Reg U S Pat amp Tm Off All other product or service names are the property of their respective ow
5. CTU into the ADC specifies e whether the actual command is a first command of a new stream of consecutive commands or not e whether an End Of Conversion EOC interrupt is issued when conversion specified by the command is finished e which channels are to be converted for both ADC modules e the target FIFO register for storing the conversion results Because the trigger compare register for trigger TOCR is set to zero it generates the ADC start of conversion request at the beginning of each PWM reload cycle When a TOCR trigger event occurs the ADC command selected by the index value TO_INDEX in command list control registers CLCR1 is sent to the ADC At each TOCR trigger event two ADC commands are executed in a stream The first command in a stream specifies two phase currents to be sampled simultaneously all phase current signals are routed to pins shared between both ADC modules The second command specifies the third phase current and DC bus voltage to be sampled The index pointer to the ADC command list TO_INDEX is updated according to the sector in which resides the actual output voltage vector calculated by the space vector modulation of the FOC algorithm There are six sectors within the output voltage hexagon of the inverter therefore six different ADC command sequences are selected for one full revolution of the voltage vector This technique is necessary when the phase current measurement is done using three shunt resistors placed i
6. e e nease DC Bu ric ie oo 4H Resolver Signals E 18 pumas EE 4 uDCB oe Ez iDQ 4 uDCB Tabe 4 Id tune a On Off Application State Sensor Option a F Name Value ON RUN Encoder swithA ppo nof ON switchAppReset OFF switchFaultClear OFF switchSensor Encoder X state STATE_RUN event e_run wea A abcFockA abcoocB i abeFack c uDQReg D 2 WORD E DQReq Q 0 2 3 Udeb 17 3 we 124 1 2 uAlBeReg A 0 288072 1 UAIBeReg B 0 561943 S thRotEl 158 435 z0 thRotElRes 53 4275 g thRotElEnc 92 0708 w 1 fa 2 i 4 5 0 0 005 0 010 0 015 0 020 0 025 0 030 0 035 0 040 Index Recorder is idle Autoload V Auto stop Autorun 4 gt recorder Done RS232 UART Communication COM3 speed 38400 Rec Idle Figure 15 FreeMASTER Control Page for controlling the application View all application state machine variables on the FreeMASTER control page as shown in Figure 15 which is a part of the MCAT tool The MCAT tool is a user friendly graphical plug in tool for FreeMASTER which enables you to easily tune and control motor control applications It supports up to three PMSM motors and is fully compliant with the FOC cascade control structure The added value of MCAT is the capability to calculate the parameters of the PI controller in the control structure All application parameters are stored and can be exported as a static configuration header file For More details about MCAT see AN4642 see Re
7. for d and q current loop It is obvious that both Equation 5 on page 4 and Equation 6 on page 4 are structurally identical therefore the same approach of controller design can be adopted for both d and q controllers The only difference is in values of d and q axis inductances which results in different gains of the controllers Considering closed loop feedback control of a plant model as in Equation 5 on page 4 or Equation 6 on page 4 using standard PI controllers then the controller proportional and integral gains can be derived using a pole placement method as follows Kp 26 L R Equation 7 Proportional gain equation K a2L Equation 8 Integral gain equation where w represents the system natural frequency rad sec and is the Damping factor of the current control loop 3 3 Phase current measurement The 3 phase voltage source inverter depicted in Figure 3 uses three shunt resistors R32 R31 and R32 placed in each of the inverter leg as phase current sensors Stator phase current which flows through the shunt resistor produces a voltage drop which is interfaced to the AD converter of microcontroller through conditional circuitry refer to 3 Phase BLDC PMSM Low Voltage Power Stage User Manual DC bus positive i D4 D5 MBR120VLSFT1G MBR120VLSFT1G nie Ry R18 R19 PA_HSG gt x aes a 4 PB_HSG Wh a PC_HSG gt PP 20 20 IRFR540Z oi p IRFR540Z P
8. state the application event is automatically set to event e init done and state READY is selected as the next state to enter 5 7 State CALIB In this state ADC DC offset calibration is performed Once the state machine enters CALIB state all PWM output are enabled Calibration of the DC offset is achieved by generating 50 duty cycle on the PWM outputs and taking several measurements of all configured ADC channels These measurements are then averaged and the average value for each channel is stored This value will be subtracted from the measured value when in normal operation This way the half range DC offset caused by voltage shift of 1 65V in conditional circuitry see Figure 4 is removed in all three phases State CALIB is a state that allows transition back to itself provided no faults are present the user does not request RESET by switchAppReset true or stop of the application by switchAppOnOff true and the calibration process has not finished The number of samples for averaging is set by default to 2 8 256 and can be modified in the state INIT After all 256 samples have been taken and the averaged values successfully saved the application event is automatically set to event e_calib_ done and state machine can proceed to state ALIGN A transition to RESET state is performed by setting the event to event e_reset which is done automatically when the user sets switchAppReset to true using FreeMASTER A transition t
9. switchFaultClear is manually set to true using FreeMASTER That is the user has acknowledged that the fault source has been removed and the application can be restarted When the user sets switchFaultClear true the following sequence is automatically executed faultID R 0x0 Clear Fault register faultIDp R 0x0 Clear Pending Fault register switchFaultClear false Reset fault clearing switch event e fault_clear new application event 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc 17 Software design Seting event to event e fault _clear while in FAULT state represents a new request to proceed to INIT state This request is purely user action and does not depend on actual fault status In other words it is up to the user to decide when to set switchFaultClear true However according to the interrupt data flow diagram shown in Figure 10 function faultDetection is called before state machine function state_table event state Therefore all faults will be checked again and if there is any fault condition remaining in the system the respective bits in fault ID and fault IDp variables will be set As a consequence of faultID and faultIDp not equal to zero function faultDetection will modify the application event from e_fault_clear back to e_fault which means jump to fall state when state machine function state _table event state is called Hence INIT st
10. the source of the fault and remove it Successful removal is signaled when the respective indicator on the FreeMaster control page turns off 10 Fault condition is also signaled by blinking LED diode D11 on the MPC5604P controller board Press UP DOWN buttons SW2 SW3 on MPC5604P controller board simultaneously to clear fault status register once in a FAULT state The application can be restarted by positioning RUN STOP switch SW4 on MPC5604P controller board to RUN position transition from STOP to RUN in case the switch was in RUN state when the fault event occurred 11 If all indicators on the FreeMaster control page are off clear pending faults by pressing the FAULT CLEAR button on the FreeMaster control page or by pressing UP DOWN buttons SW2 SW3 on MPC5604P controller board simultaneously The RUN STOP switch SW4 on MPC5604P controller board must be in position STOP 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc 25 References 12 13 14 15 NYDN WN KE 8 Start the application by clicking the On Off button on the FreeMaster control page or by positioning RUN STOP switch SW4 on MPC5604P controller board to RUN position transition from STOP to RUN in case the switch was in RUN state when the fault event occurred Enter required speed by assigning this value to Nreq variable in the variables watch window or use the speed gauge in the PMSM Control Pag
11. user manual for MPC5604P found at www freescale com see References for more information N 2015 Freescale Semiconductor Inc y Xs freescale I PMSM field oriented control e Running on the MPC5604P Control Drive board refer to dedicated user manual for MPC5604P Controller Board see References for more information e Control technique incorporating e Vector control of 3 phase PM synchronous motor with position sensor e Closed loop speed control e Bi directional rotation Both motor and generator modes e Close loop current control e Flux and torque independent control e Start up with alignment e Reconstruction of three phase motor currents from two shunt resistors e 100 us sampling period with FreeMASTER recorder e FreeMASTER software control interface motor start stop speed setup see References for more information e FreeMASTER software monitor e FreeMASTER software graphical control page required speed actual motor speed start stop status DC Bus voltage level motor current system status e FreeMASTER software speed scope observes actual and desired speeds DC Bus voltage and motor current e FreeMASTER software high speed recorder reconstructed motor currents vector control algorithm quantities e DC Bus over voltage and under voltage over current overload and start up fail protection e Motor Control Application Tuning MCAT tool see References e The MCAT tool is a user friendly graphical Free
12. via RS232 and or slow refresh rate of the control page After the application faults have been cleared and the application is in READY state all variables should be set to their default values The application can be started by clicking the On Off button A successful selection is indicated by highlighting the On Off button in green If there is no fault detected in the system after starting the application by clicking on the On Off button the application should proceed to CALIB state for DC offset calibration then to ALIGN state for marking the zero position and finally state RUN is entered When in RUN state all control loops of FOC algorithm are active That means 3 phase currents are measured and used to close the current loop and actual rotor speed is measured for closing the speed loop The user can now select the desired speed of the rotor in the variable watch window or by selecting the required speed in Rotor speed control rpm application gauge on the FreeMaster control page Click on the speed scale of the gauge to make the selection The variable for controlling the speed is called Nreq and it is the required speed recalculated to mechanical speed in revolutions per minute Because of the used motor the required speed can be selected from 4000 rpm to 4000 rpm Field weakening algorithm is not implemented therefore the required value of d axis current is set to zero 6 1 Application quick start 1 Install USB driver t
13. 937_TLIM over temperature not used in current software version e FLT12 MC33937_DESAT desaturation detected not used in current software version e FLT13 MC33937_VLS low VLS detected not used in current software version e FLT14 MC33937_OC over current detected not used in current software version e FLT15 MC33937_PhaseE phase error not used in current software version e FLT16 MC33937_FrameE SPI communication frame error not used in current software version e FLT17 MC33937_WriteE SPI communication write error not used in current software version e FLT18 MC33937_RST reset event not used in current software version e FLT21 FOCError error in FOC calculation function e FLT22 AlignError error during alignment e FLT23 CalibError error during ADC calibration e FLT24 InitError error during app initialization e FLT29 FLEXPWM_Error error in FlexPWM hardware initialization 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 18 Freescale Semiconductor Inc Software design e FLT30 ADC_Error error in ADC hardware initialization e FLT31 CTU_Error error in CTU hardware initialization 5 6 State INIT State INIT is similar to state RESET one pass state function and can be entered from all states except for READY state provided there are no faults detected All application variables and parameters are initialized in state INIT After the execution of INIT
14. A _HSSC PB_HSS lt lt PC_HSS lt D7 D8 D9 MBR120VLSFT1G MBR120VLSFT1G MBR120VLSFT1G R22 R23 R24 R25 R26 R27 PA_LSGY ANAN ANN 1 os PB_LSG gt aA aS 1 a6 PC_LSG gt a ANNAN 1 a7 PALSS lt 20 20 IRFR540Z PB LSS K 20 20 IRFR540Z PC _iss 20 20 IRFR540Z 1_sense_AP lt C I_sense_BP lt I_sense_CP R30 R32 0 004 0 004 1_sense_AN lt _sense_BN lt _sense_CN lt R33 i DC bus negative Figure 3 3 phase DC AC inverter with shunt resistors for current measurement Figure 4 shows an operational amplifier and input signal filtering circuit which provides the conditional circuitry and adjusts voltages to fit into the ADC input voltage range 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc 5 PMSM field oriented control C57 R73 I_sense_BN gt Decoupling capacitor C48 _sense_BP gt Place as close as possible to V pin O 1 65Vref AGND 33k Figure 4 Phase current measurement conditional circuitry The phase current sampling technique is a critical issue for detection of phase current differences and for acquiring full three phase information of stator current by its reconstruction Phase current flowing through shunt resistors produces a voltage drop which needs to be appropriately sampled by the AD converter when low side transistors are switched on The current cannot be measured by the current shunt resistors at an arbitrary moment This is beca
15. MASTER s plug in tool for debugging and tuning of motor control applications 3 PMSM field oriented control 3 1 Fundamental principle of PMSM FOC High performance motor control is characterized by smooth rotation over the entire speed range of the motor full torque control at zero speed and fast acceleration deceleration To achieve such control vector control techniques are used for PM synchronous motors The vector control techniques are usually also referred to as field oriented control FOC The FOC concept is based on an efficient torque control requirement which is essential for achieving a high control dynamic Analogous to standard DC machines AC machines develop maximal torque when the armature current vector is perpendicular to the flux linkage vector Thus if only the fundamental harmonic of stator mmf is considered the torque T developed by an AC machine in vector notation is given by Te 3 PP is Equation 1 Electric motor torque where pp is the number of motor pole pairs i is stator current vector and W represents vector of the stator flux Constant 3 2 indicates a non power invariant form of transformation used In instances of DC machines the requirement to have the rotor flux vector perpendicular to the stator current vector is satisfied by the mechanical commutator Because there is no such mechanical commutator in AC Permanent Magnet Synchronous Machines PMSM the functionality of the commutator has to be s
16. OC calculation 5 9 1 Current measurement Three phase currents are obtained by calling ADC_Measure2Ph function As described in Phase current measurement only two currents are measured at a time and third current is calculated Which currents are measured and which calculated depends on a sector in which lies the actual output voltage vector The sector is calculated by GMCLIB_SvmStd function which generates three phase duty cycles for the inverter by employing Space Vector Modulation technique The 3 phase inverter can switch six active voltage vectors and two zero vectors These are given by combinations of the corresponding power switches Plotting all six active vectors in a complex plane results in a hexagon with six sectors 5 9 2 Position speed measurement Information about rotor position is obtained by calling function POSPE_GetPosElEnc if an encoder is used or POSPE_GetPosElRes if a resolver is used as position sensor Both functions calculate the angle tracking observer which is implemented using PI controller and an integrator Output of the integrator represents the estimated tracked position which is subtracted from the measured position from the sensor and the resulting difference is used as an error signal for the PI controller Because the integrator is connected to the PI controller output the PI controller output represents the estimated angular velocity of the rotor 3 Phase PMSM Motor Control Kit with the M
17. PC5604P Rev 1 11 2015 Freescale Semiconductor Inc 21 Software design To obtain information about the rotor position speed the parameters of the tracking observer such as Kp and Ki gains of PI controller and input and output scales of the integrator must be properly configured 5 9 2 1 Encoder sensor If an encoder is used as a position sensor the information about rotor position is obtained by reading the value of the timer eTimer1 CHO see eTimer1 for configuration of eTimer module Because the encoder is a relative position sensor the counter timer used for counting the encoder edges has to be correctly reset at the start of operation This is done in ALIGN state where a constant current is applied in the d axis with position manually set to zero The current amplitude must be chosen large enough to cause rotor movement but must not damage the stator winding Usually a current amplitude of 10 20 is sufficient This current is applied for a fixed period of time in order to allow motor to settle in an align position where stator and rotor fluxes are aligned This position is then set as zero position and counter eTimer1 CH0 is set to zero HW SW GDFLIB_FilterMA POSPE_GetSpeedElEnc phase A eTimert CHO ness By thRotElEnc POSPE_GetPositionElEnc Dick wRotElEnc Figure 13 Angle tracking observer used for position speed estimation using encoder 5 9 2 2 Resolver sensor If a resolver is used as a posit
18. al v amp amp u amp 22 amp o amp ADC Command 8 ix Vv dual x amp 13 e o fi ADC Command 9 M S dual T T fu amp fiz amp fo amp ADC Command 10 fg Iv ua O 3 te ES E ES 1 ADC Command 11 M ES dual v tv w iz 13 amp lo amp ADC Command 12 I M dual J J 9 fu bhe he H ADC Command 13 M RC dual b o amp lo amp ADC Command 14 a r a Q amp amp bp Of Ob amp ADC Command 15 i aa O o amp lo amp lo amp ADC Command 16 E ii dual o amp amp fo amp lo amp fo amp ADC Command 17 a a dual wy amp gt amp o amp fo amp ADC Command 18 Pe amp dual v amp fo o o ADC Command 19 12 amp aa o amp amp fo amp fo amp o amp ADC Command 20 ig E dual v amp amp gt amp gt amp fo amp ADC Command 21 ja a dual 9 amp fo amp o o ADC Command 22 Pr RS dual o e o amp o amp o amp ADC Command 23 g g dual Ol amp lo Slo amp fo amp Figure 6 Configuration of CTU ADC commands for the PMSM FOC application 4 3 eTimerO This eTimer module is only used for generation of an excitation signal for resolver Because of hardware design channel 5 of this eTimer module is selected The purpose is to generate a square wave signal with a frequency of 10 kHz which is then processed by a hardwar
19. ate will not be entered even though the user tried to clear the fault flags using switchFaultClear When the next state INIT is entered all fault bits are cleared which means no fault is detected faultIDp R 0x0 and application variable switchFaultClear is manually set to true 5 5 1 Application faults Both faultID and fault IDp are defined as AppFault Status which is a 32 bit long data type Application faults are bit mapped in AppFaultStatus type as follows Table 1 AppFaultStatus type 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 FLT FLT FLT RESERVED FLT FLT FLT FLT RESERVED FLT FLT FLT 31 30 29 24 23 22 21 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 FLT FLT FLT FLT FLT FLT FLT9 FLT8 FLT7 FLT6 FLTS FLT4 FLT3 FLT2 FLT1 FLTO 15 14 13 12 11 10 e FLTO OverDCBusVoltage Over voltage on DC bus e FLT1 UnderDCBusVoltage Under voltage on DC bus e FLT2 OverDCBusCurrent Over current on DC bus e FLT3 OverLoad Overload Flag e FLT4 MainsFault Mains out of range e FLTS5 WrongHardware Wrong hardware fault flag e FLT6 OverHeating Overheating fault flag e FLT7 OverPhaseACurrent Over current on phase A e FLTS8 OverPhaseBCurrent Over current on phase B e FLT9 OverPhaseCCurrent Over current on phase C FLT10 OffCancError Offset cancellation error e FLT11 MC33
20. ation event and the second parameter describes the actual application state These two parameters select a particular pointer to state machine function which causes a function call whenever state _table is called 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc 15 Software design Figure 11 Application state machine The application state machine consists of following seven states which are selected using variable state defined as AppStates e RESET state e INIT state 1 e FAULT state 2 e READY state 3 e CALIB state 4 e ALIGN state 5 e RUN state 6 0 To signalize initiate a change of state thirteen events are defined and are selected using variable event defined as AppEvents e e_reset event 0 e e_reset_done event 1 e e fault event 2 e e_fault_clear event 3 e e_init_done event 4 e e_ready event 5 e e_app_on event 6 e e_app_off event 12 e e_calib event 7 e e_calib_done event 8 e e_align event 9 e e_align_done event 10 e e_run event 11 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 16 Freescale Semiconductor Inc Software design 5 4 State RESET State RESET is the first state the state machine enters after power on or reset in other words when the application enters main function In RESET state all used peripherals are reset and configured as required
21. by the application see MPC5604P CB configuration Before configuring peripheral modules all interrupts are disabled Interrupts are enabled at the end of RESET state Therefore the periodic CTU ADC interrupt is not requested and the state machine functions cannot be executed until all interrupts are enabled and all peripherals set State RESET is a one pass function state It is entered and executed only once and the next state is called after RESET is finished If there is no error fault during RESET execution the application event is set to event e_reset_done and all interrupts are enabled at the end of the function From this point the CTU ADC interrupts are enabled and if the peripherals are correctly configured the next call of state machine function will be from within the CTU ADC interrupt service routine According to the data flow diagram of the CTU ADC interrupt service routine shown in Figure 10 the routine for three phase current reconstruction ADC_Measure2Ph is executed first followed by the rotor position measurement routine The fault detection function is always called before the state machine function call ensuring correct transition to FAULT state in case a fault is detected If there is no fault detected the application event remains set to event e_reset_done hence INIT state will be selected as the next state to execute The user can initiate a jump to RESET state from any state of the state machine by setting the ev
22. cos qD sin phase em cos ADC conversion cmmd ISR service routine Figure 8 FlexPWM CTU ADC conversion timing 5 Software design 5 1 Introduction This section describes the software design of the PMSM Field Oriented Control framework application First the application overview and description of software implementation are provided Then the numerical scaling in fixed point fractional arithmetic of the controller is discussed followed by a detailed description of speed and current sensing The aim of this chapter is to help in understanding of the designed software 5 2 Application data flow overview The application software is interrupt driven running in real time There is one periodic interrupt service routine associated with the CTU ADC command interrupt request executing all motor control tasks These include both fast current and slow speed loop control All tasks are performed in an order described by the application state machine shown in Figure 11 and application flowcharts shown in Figure 9 and Figure 10 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc 13 Software design state reset event e_reset state_table false Figure 9 Flow chart diagram of main function with background loop To achieve precise and deterministic sampling of analog quantities and to execute all necessary motor control calculations the state machi
23. d on occurrence of MRS therefore update of new PWM duty cycles is done every two PWM periods FlexPWM modulo counting for generation of centrr aligned PWM signals is achieved by setting VALO register to zero and INIT register to negative value of VAL1 Considering PWM clock of 120 MHz required PWM output 20 kHz and PWM reload period 100 us then INIT VALO and VALI registers of sub modules 0 1 2 are set as follows e INIT 120000000 20000 2 3000 DEC 0xF448 e VALO 0 DEC e VALI INIT 3000 DEC 0x0BB8 Reload frequency of sub modules 0 1 2 is set to Every two opportunities and Full cycle reload is enabled in all sub modules Because sub module 0 is a master that generates MRS signal reload of double buffered registers of sub module 0 is done on Local Reload Sub modules 1 and 2 are slaves so reload of their double buffered registers is done on Master Reload broadcast from sub module 0 Similarly the sub module 0 counter is initialized on Local Sync event while sub modules 1 and 2 on Master Sync event which is also broadcast from sub module 0 Because some registers are double buffered on occurrence of FORCE OUT signal all sub modules have Local Reload event selected as force source All PWM channels are used to drive a 3 phase DC AC inverter so each PWM pair is driven in complementary mode with dead time automatically added on each rising edge of respective PWM signal Used power stage with MC33937 pre dri
24. e low pass filter designed on used controller board Because of the low pass filter the resulting harmonic signal is phase shifted In order to generate a square wave signal synchronized with the MRS signal timer channel 5 of module eTimer0 eTimer1 ETC 5 is configured as follows e counting mode Edge of secondary source triggers primary count until compare e count direction Count up e primary source IPBus clock e secondary source AUX 0 which is an output signal from CTU ETIMER 0 trigger event output 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 10 Freescale Semiconductor Inc C MPC5604P CB configuration e count stop mode Count repeatedly e count length Count until compare then reinitialize e compare mode Use COMP1 when counting up and COMP2 when counting up output mode Toggle OFLAG on successful compare with COMP1 and or COMP2 e COMP 0x0 e COMP2 0x0 e LOAD 0x0 e direction of the channel pin Output OFLAG 4 4 eTimert This eTimer module is only used for decoding two square wave signals from an encoder Because of hardware design channel 0 of this eTimer module is selected The purpose is to decode the two 90 shifted square wave signals and count up or down all rising falling edges based on their sequences The software routine then reads the associated counter value to get the information about rotor position Reading of the counter value is perf
25. e that responds to a mouse click Value is in revolutions per minute Alternatively rotor speed can be increased decreased by pressing UP DOWN switches on MPC5604P controller board RUN STOP switch SW4 on MPC5604P controller board must be in START position Stop the application by clicking the On Off button on the FreeMaster control page or by positioning RUN STOP switch SW4 on MPC5604P controller board to STOP position RESET the application at any time by entering the value 1 to the switchAppReset variable in the Variable Watch window References MPC560xP Controller Data sheet document MPC5604P MPC560xP Controller Board User s Guide document MPC5604PMCBUG FreeMASTER Run Time Debugging Tool www freescale com FREEMASTER Automotive Math and Motor Control Library Set www freescale com AutoMCLib MC33937 Three Phase Pre driver Data Sheet document MC33937 Motor Control Application Tuning MCAT Tool for 3 Phase PMSM document AN4642 Motor Control Application Tuning MCAT Tool www freescale com MCAT Revision history This section documents the changes done to this document Table 2 Revision history 0 10 2012 Initial release 1 11 2015 Updated Figure 15 Updated Sections 1 2 6 and 7 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 26 Freescale Semiconductor Inc How to Reach Us Home Page freescale com Web Support freescale com support
26. ent to event e_reset This is done by setting switchAppReset variable to true using FreeMASTER The entire RESET procedure as described above is then repeated The following sequence is performed in this order e interrupts disable e all peripherals reset and configure e user control and fault variables reset switchApponoff false switchApponoffState false switchFaultClear false switchAppReset false faultID R 0x0 faultIDp R 0x0 e event set to event e_reset_done e interrupts enable 5 5 State FAULT The application goes immediately to this state when a fault is detected The system allows all states to pass into the FAULT state by seting event e fault State FAULT is a state that allows transition back to itself if a fault is present in the system and the user does not request clearing of fault flags There are two different variables to signal fault occurrence in the application The actual fault register fault ID represents the current state of the fault pin variable etc and the pending fault register fault IDp represents a fault flag which is set once actual fault is was true Even if the actual fault is reset fault source disappears the pending fault remains set until manually cleared by the user Such mechanisms allow for stopping the application and analyzing the cause of failure even if the fault was caused by a short glitch on monitored pins variables State FAULT can only be left when application variable
27. ets and 9 is electrical rotor angle B torque producing flux producing stator coordinates Figure 2 Orientation of stator stationary and rotor rotational reference frames with current components transformed into both frames The voltage equation of the quadrature phase synchronous reference frame model can be obtained by transforming the three phase voltage equations Equation 1 on page 2 Equation 2 on page 3 into a two phase rotational frame which is aligned and rotates synchronously with the rotor as shown in Figure 2 Such transformation after some mathematical corrections yields the following set of equations ua ia La 9 Lq ia 0 Plas GMa AN lara Equation 4 DQ voltage model of PMSM It can be seen that Equation 4 on page 4 represents a non linear cross dependent system with cross coupling terms in both d and q axis and back EMF voltage component in the q axis When FOC concept is employed both cross coupling terms shall be compensated in order to allow independent control of current d and q components Design of the controllers is then governed by following pair of equations derived from Equation 4 on page 4 after compensation es dig Ug Rsigt Lage Equation 5 D axis voltage 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 4 Freescale Semiconductor Inc PMSM field oriented control dig Uq Rsigt Loge Equation 6 Q axis voltage which describes the model of the plant
28. ferences Permanent pending faults are signaled by a highlighted red color bar with name of the fault source Actual faults are signaled by a round LED like indicator which is placed next to the bar with the name of the fault source The actual presence of any fault is signaled by highlighting respective indicators In the previous figure for example there are five pending faults and one actual fault Udcb LO DC bus under voltage That means that low voltage on the DC bus is still present in the system The other pending faults highlighted in the figure above indicate there was an error latched but it is no longer present in the system In this case the application state FAULT is selected which is shown by a frame indicator hovering above FAULT state in the middle of the control page 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 24 Freescale Semiconductor Inc Application control user interface After all actual fault sources have been removed no fault indicators are highlighted The pending faults can now be cleared by pressing the FAULT CLEAR button This will clear all pending faults and will enable transition of the state machine into INIT and then READY state Because INIT is a one pass state transitions to FAULT INIT READY happen faster than the control page can display which may seem as if the state machine went from FAULT to READY directly This is not an error and is caused by slow communication
29. ging tool FreeMASTER is used see References An example software package of the MPC5604P Development Kit contains a related FreeMASTER project An integral part of the FreeMASTER project is also the Motor Control Application Tuning MCAT tool see References Communication with the host PC is via USB However because FreeMASTER supports RS232 communication there must be a driver installed on the host PC that creates a virtual COM port from the USB This COM port can then be used for FreeMASTER communication The application configures the LINFlex module of MPC5604P for communication speed 38400 bps Therefore FreeMASTER must also be set for this speed This can be done in FreeMASTER menu Project gt Options gt by selecting tag Comm 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc 23 AE Application control user interface z _ a MPC5604P_PMSM Kit MCAT tox MA Eo Bo Be Sb eee 2 DI gt elko s ta Ela ESN Tahoma es aie eo ee File Edit View Recorder Project Tools Help ee pr pegs oa e 2 7 freescale Motor Control Application Tuning Tool E gt Speed p 4 Tabe 4 uDCB Motor 1 PMSM Tuning Mode Expert y 4 Position OL vs Sensors 452 Speed 4 labc E 2 upce F PMSM Control Page gt iDQ fi Id tune Application Faults g 10 15 20 25 30 A Iq tune 0 35 EMS Torque Current loop e
30. ion sensor the information about rotor position is obtained by reading values of the ADC A channel 1 and ADC B channel 1 The timer eTimer0 CHS is used for generation of an exciting signal for the resolver see eTimer0 for configuration of eTimer0 module The resolver is an absolute position sensor and there is no need for a mechanical alignment However the resolver either has to be mounted precisely on the rotor shaft where the aligned position of rotor and stator fluxes result in resolver sin cos signals representing zero or an offset between real zero position and zero position indicated by the resolver sin cos signals must be a known a priory This offset is then always subtracted from the measured position Initialization of the resolver offset is done at the end of an align procedure ALIGN state by writing the value measured from a resolver during alignment into the offset 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 22 Freescale Semiconductor Inc Application control user interface GDFLIB_FilterMA HW SW Dink wRotElRes POSPE_GetSpeedElRes ADC A CH1 ADC B CH1 eTimer0 CH5 Figure 14 Angle tracking observer used for position speed estimation using resolver Oho thRotElRes Resolver POSPE_GetPesitionElRes 6 Application control user interface To control the application and monitor variables during run time the Freescale run time debug
31. ization of simple current controllers to control the demanded torque and magnetizing flux of the machine thus simplifying the control structure design Figure shows the basic structure of the vector control algorithm for the PM synchronous motor To perform vector control it is necessary to perform these steps e Measure the motor quantities phase voltages and currents rotor speed and position Transform them into the two phase system a P using a Clarke transformation Transform stator currents into the d q reference frame using a Park transformation Also keep these points in mind The stator current torque isq and flux isq producing components are separately controlled e The output stator voltage space vector is calculated using the decoupling block e The stator voltage space vector is transformed by an inverse Park transformation back from the d q reference frame into the two phase system fixed with the stator e The output three phase voltage is generated using a space vector modulation To be able to decompose currents into torque and flux producing components isq isq position of the motor magnetizing flux has to be known This requires accurate sensing of the rotor position and velocity Incremental encoders or resolvers attached to the rotor are naturally used as position transducers for vector control drives d d chase 3 Phase Stationary Rotating Phase A Phase B to to to SVM Phase B PhaseC
32. lign_done This enables a transition to RUN state A transition to RESET state is performed by setting the event to event e_reset which is done automatically when the user sets switchAppReset to true using FreeMASTER 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc 19 Software design A transition to FAULT state is performed automatically when a fault occurs Transition to INIT state is performed by setting the event to event e_app_off which is done automatically on falling edge of switchAppOnOff false using FreeMASTER 5 9 State RUN In this state all calculations for FOC algorithm as described in PMSM field oriented control are performed Calculation of fast current loop is executed every CTU ADC interrupt when in RUN state while calculation of slow speed loop is executed every Nth CTU ADC interrupt Arbitration is done using a counter that counts from value N down to zero When zero is reached the counter is reset back to N and slow speed loop calculation is performed This way only one interrupt is needed for both loops and timing of both loops is synchronized Slow loop calculations are finished before entering fast loop calculations Figure 12 shows implementation of FOC algorithm and the functions and variables used As can be seen from the diagram position speed measurement is prepared for Encoder as well as for Resolver sensor Encoder sensor feedback is selected as default
33. n the bottom side of each inverter leg Because the shunt resistor is placed at the bottom side of the inverter leg the phase current can be measured only when bottom transistor is switched on Because the sum of the three currents in the motor windings is zero only two currents are measured and the third one is calculated Which phases are measured and which are calculated changes according to the voltage vector angle i e the phases with the largest PWM on pulse on the bottom transistors are selected to get the best current information Configuration of CTU ADC commands is shown in Figure 6 1 These triggers are only necessary when using resolver position sensor 2 These trigger event outputs are only necessary when using resolver position sensor 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc 9 es MPC5604P CB configuration ADC Command List Dg eee ape ADC ADCA ADCB command Interrupt Conversion Mode Module Channel Channel Channel FIFO ADC Command 0 M E dual T TB ti amp fi amp IHS ADC Command 1 M j dual amp T T z amp IS be i ADC Command 2 Pr iv dual amp 11 amp lo amp 1 amp ADC Command 3 M amp dual 7 To Lo a 3 amp bo oi ADC Command 4 j M dual S Jy JT 9 re bO he Ki ADC Command M ai ua O EIS 13 amp o amp ADC Command 6 De M aa O J 9 IEIS bo ho 1 ADC Command 7 M f du
34. ne functions are called within a periodic interrupt service routine Hence in order to actually call state machine functions the periphery causing this periodic interrupt must be properly configured and the interrupt enabled As is described later all peripherals are initially configured and all interrupts are enabled within a state RESET of the state machine Therefore state machine is called once in main function before the background loop to enter RESET state and to enable interrupts As soon as interrupts are enabled and all peripheries are correctly configured see MPC5604P CB configuration for configuration of peripherals the state machine functions are called from the CTU ADC interrupt service routine The background loop handles non critical timing tasks such as the FreeMASTER communication polling 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 14 Freescale Semiconductor Inc Software design ADC_Measure2Ph POSPE_GetPositionE Res DCBus resistor braking falling edge apo of B switchAppOnOff faultDetection faultIDp 0x0 j rising edge _opp_on e fault switchAppReset state_table e reset Figure 10 Flow chart diagram of periodic interrupt service routine 5 3 State machine The application state machine is implemented using a two dimensional array of pointers to the functions variable called state_table The first parameter describes the current applic
35. ners 2015 Freescale Semiconductor Inc Document Number AN4561 Revision 1 11 2015 e Po oe freescale
36. nimal pulse width A D sampling Figure 5 Generated phase duty cycles in different PWM periods In case of standard motor operation where the supplied voltage is generated using the space vector modulation the sampling instant of phase current takes place in the middle of the PWM period in which all bottom transistors are switched on If the modulation index of applied SVM technique increases there is an instant when one of the bottom transistors is switched on for a very short time period Therefore only two currents are measured and the third one is calculated from equation istiptic 0 Equation 9 Currents in three phase balanced system Therefore a minimum on time of the low side switch is required for three phase current reconstruction 4 MPC5604P CB configuration The PMSM Speed Field Oriented Control framework application software and hardware is designed to meet the following technical specifications MPC5604P Controller Board is used refer to dedicated user manual for MPC5604P Controller Board 3 phase low voltage power stage with MC33937 pre driver is used e refer to dedicated user manual for 3 phase low voltage power stage with MC33937 pre driver See References for more information e refer to dedicated user manual for MC33937 pre driver on www freescale com e refer to dedicated document describing communication with and configuration of MC33937 pre driver using DSPI communication bus PWM output frequency 20 kHz cu
37. ntrol Kit with the MPC5604P Rev 1 11 2015 8 Freescale Semiconductor Inc C MPC5604P CB configuration e 1 TICR 0x099C 2460 DEC e T2CR 0x210C 8460 DEC e T3CR 0x2DF0 11760 The CTU Scheduler subUnit SU generates the trigger event output according to the trigger event that occurred The following trigger event outputs are generated e ADC command output TOCR generates ADC command event output with command offset initially set to one It is used as synchronization signal to ADC ADC commands 1 12 for phase current and DC bus voltage measurement e eTimer0 output TICR generates eTimer0 event output which toggles its output to generate rising edge of resolver exciting signal T1CR is phase shifted to account for delay caused by the MPC5604P resolver hardware circuitry and to allow ADC sampling of resolver signals just before PWM reload e eTimer0 output T2CR generates eTimer0 event output which toggles its output to generate falling edge of the resolver exciting signal frequency of resolver exciting signal is resolverSignalFreq MC_PLL_CLK 2 T2CR TICR 120000000 2 8460 2460 10kHz e ADC command output T3CR generates ADC command event output with command offset set to zero It is used as synchronization signal to ADC ADC command 0 for resolver signals sampling The SU uses a Commands List in order to select the command to send to the ADC when a trigger event occurs Each ADC command sent by the
38. o FAULT state is performed automatically when a fault occurs A transition to INIT state is performed by setting the event to event e_app_off which is done automatically on falling edge of switchAppOnOff false using FreeMASTER 5 8 State ALIGN This state shows alignment of the rotor and stator flux vectors to mark zero position only necessary for relative position sensors such as encoders etc When using a relative position sensor such as an encoder the zero position is not known and therefore counting of encoder edges has to be correctly reset at the start of operation This is done in ALIGN state where a DC voltage is applied in phase A for a certain period This will cause the rotor to rotate to align position where stator and rotor fluxes are aligned The rotor position in which the rotor stabilizes after applying this DC voltage is set as zero position therefore the timer eTimer1 CHO is reset to zero In order to wait for rotor to stabilize in an aligned position a certain time period is selected during which the DC voltage is constantly applied The period of time and the amplitude of DC voltage can be modified in INIT state Timing is implemented using a software counter that counts from a pre defined value down to zero During this time the event remains set to event e align When the counter reaches zero the counter is reset back to the pre defined value timer eTimer1 CHO is reset and event is automatically set to event e_a
39. o create a virtual COM port for emulation of RS232 communication for example CP210x USB to UART Bridge VCP Drivers available from https www silabs com Support 20Documents Software CP210x_VCP_Win2K_XP_S2K3 zip 2 Connect USB cable to MPC5604P controller board and to host PC 3 Connect power supply to the power stage Controller board power supply is taken from the power stage The PMSM motor used is designed for phase voltage 18V 4 Start FreeMASTER project located in MPC5604P_PMSM_Development_Kit FreeMASTER_control MPC5604P_PMSM_Development_Kit_MCAT pmp 5 Enable communication by pressing STOP button in the toolbar in FreeMASTER or by pressing CTRL K 6 Successful communication is signaled in the status bar see Figure 15 for example 7 GPIOA13 is turned ON at the beginning of the calculation step and turned OFF at the end The period of calculation is 100 us so the LED D18 on MPC5604P controller board will flash with a period of 10 kHz if the application runs correctly 8 Functionality of GPIO12 LED D11 on MPC5604P controller board is as follows e OFF if the application is in READY INIT states e ON if the application is in RUN CALIB ALIGN states e flashing if the application is in FAULT state flashing with period 1 2 Hz so that it is clearly visible with the naked eye 9 If no actual faults are present in the system all indicators on the FreeMaster control page are dark red If there is a fault present identify
40. ormed from within POSPE_GetPositionElEnc function periodically within CTU ADC interrupt service routine See the data flow diagram shown in Figure 10 In order to decode the encoder signals timer channel 0 of module eTimer1 eTimer1 ETC 0 is configured as follows counting mode Quadrature count mode uses primary and secondary sources e count direction Count up e primary source Counter 1 input e secondary source Counter 2 input count stop mode Count repeatedly e count length Count until compare then reinitialize e preload control for CNTR e Load CNTR with CMPLD 1 upon successful compare with COMP2 e Load CNTR with CMPLD2 upon successful compare with COMP1 e compare mode Use COMP when counting up and COMP2 when counting down output mode Toggle OFLAG on successful compare with COMP1 and or COMP2 e COMP 0x07FF 2047 DEC e COMP2 0xF800 2048 DEC e CMPLD 0x07FF 2047 DEC e CMPLD2 0xF800 2048 DEC e LOAD 0x0 this value is updated by a software routine during ALIGN phase The compare registers of eTimer0 channel 0 are set according to the number of encoder pulses per one mechanical revolution In this case an encoder sensor with 1024 pulses is used Considering quadrature mode the encoder has a capability of position recognition with a precision that is four times higher than the number of pulses in the application for a maximum number of edges of 4096 The compare registers are calc
41. rrent loop sampling period 100 us speed loop sampling period 2 ms 3 phase current measurement using three shunt resistors on bottom side of each inverter leg Phase current measurement feedback is routed to ADCO and ADC1 as follows e phase A current ADCO 1 CH12 e phase B current ADCO 1 CH13 e phase C current ADCO 1 CH14 DC bus voltage measurement routed to ADC1 as follows e DC bus voltage ADC1 CHO encoder position feedback routed to eTimer1 module as follows e phase A eTimer CH1 input e phase B eTimer1 CH2 input 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc Tl MPC5604P CB configuration e resolver excitation signal routed from eTimer0 CH5 e resolver position feedback routed to ADCO and ADC1 as follows e resolver sin ADCO CH1 e resolver cos ADC1 CH1 4 1 FlexPWM The MPC5604P Clock Generation Module is configured to generate a clock signal of 120 MHz on the MC_PLL_CLK bus The FlexPWM module is clocked from the MC_PLL_CLK therefore it is placed behind the IPS Bus Clock Sync Bridge The FlexPWM sub module 0 is configured to run as a master and to generate Master Reload Signal MRS and counter synchronization signal master sync for other sub modules The MRS signal is generated every second opportunity of sub module 0 VAL1 compare i e full cycle reload All double buffered registers including compare registers VAL2 VAL3 VAL4 VALS are update
42. ubstituted electrically by enhanced current control This suggests orientating the stator current vector in so that the component of stator current magnetizing the machine flux component is isolated from the torque producing component 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 2 Freescale Semiconductor Inc SSS PMSM field oriented control This can be accomplished by decomposing the current vector into two components projected in the reference frame often called the dq frame that rotates synchronously with the rotor It has become standard to position the dq reference frame such that the d axis is aligned with the position of the rotor flux vector so that the current in the d axis will alter the amplitude of the rotor flux linkage vector The reference frame position must be updated so that the d axis will be always aligned with the rotor flux axis Because the rotor flux axis is locked to the rotor position when using PMSM machines a mechanical position transducer can be utilized to measure the rotor position and the position of the rotor flux axis When the reference frame phase is set such that the d axis is aligned with the rotor flux axis the current in the q axis represents solely the torque producing current component What further results from setting the reference frame speed to be synchronous with the rotor flux axis speed is that both d and q axis current components are DC values This implies util
43. ulated as follows e COMP 4096 2 1 0x07FF 2047 DEC e COMP2 4096 2 OxF800 2048 DEC 4 5 On chip motor control peripherals interconnection 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 Freescale Semiconductor Inc 11 MPC5604P CB configuration f Figure 7 MPC5604P motor control peripherals connection 4 6 ADC conversion and interrupt timing Configuration of FlexPWM CTU and eTimer0 peripheral modules as described in FlexPWM CTU and eTimer0 results in a sequence of trigger events that are shown in the following figure The application state machine functions are called from an interrupt service routine which is associated with CTU ADC command interrupt request As can be seen from ADC command list configuration shown in Figure 6 the ADC command interrupts are linked with CTU trigger TOCR in other words when measurement of phase currents and DC bus voltage is finished 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 12 Freescale Semiconductor Inc Software design Full Cycle Reload Every Second Opportunity VAL1 VAG fer ere a ia A Ga TES all ce A i FlexPWM sub0 counter VALO VAL2 l eee A CE n E EES EEA ee ES n ENEE A EE A oe INIT i H i i i H A bot PWM f PWM FlexPWM MRS reload deadtime reload TY 0 Trig 1 g 0 CTU triggers rig 3 eTimer0 compare eTimer0 OFLAG Resolver sin
44. use that the current only flows through the shunt resistor when the bottom transistor of the respective inverter leg is switched on Therefore considering the diagram depicted in Figure 3 phase A current is measured using the R30 shunt resistor and can only be sampled when the transistor Q5 is switched on Correspondingly the current in phase B can only be measured if the transistor Q6 is switched on and the current in phase C can only be measured if the transistor Q7 is switched on In order to get an actual instant of current sensing voltage waveform analysis has to be performed Generated duty cycles phase A phase B phase C of two different PWM periods are depicted in Figure 5 These phase voltage waveforms correspond to a center aligned PWM with sinewave modulation As shown in the following figure PWM period I the best sampling instant of phase current is in the middle of the PWM period where all bottom transistors are switched on However not all three currents can be measured at an arbitrary voltage shape PWM period II in the following figure shows a case when the bottom transistor of phase A is on for a very short time If the on time is shorter than a certain critical time depends on h w design the current cannot be correctly measured 3 Phase PMSM Motor Control Kit with the MPC5604P Rev 1 11 2015 6 Freescale Semiconductor Inc Duty cycles v A wo MPC5604P CB configuration PWM reload PWM reload PWM reload Mi
45. ver inverts the polarity of PWM signals for top transistors active low logic so PWM A output polarity in all sub modules is set as Inverted Therefore during fault state the output of PWM A of each sub module is set to logic one The FlexPWM module includes a Fault Protection logic which can control any combination of PWM output pins and automatically disable PWM outputs during a fault state Faults are generated by a logic one on any of the FAULTx pins In order to enable mapping of all fault pins fault disable mapping registers DISMAP of all sub modules must be enabled logic one 4 2 CTU The MRS signal generated from the FlexPWM module is internally routed to the CTU module where it is selected using the input selection register Trigger Generator Subunit Input Selection Register TGSISR as source of master reload signal for CTU This signal is used for reload trigger compare registers and reloads the TGS counter with the value stored in TGS counter reload register The TGS counter register is used to compare the current counter value with the values of trigger compare registers when the two values are the same an event is generated TGS is configured in triggered mode Because the MRS signal is generated every two PWM periods the CTU counter can count up to value of 12000DEC when the initial value is set to zero The following TGS trigger compare registers are used for trigger events e TOCR 0x0 0 DEC 3 Phase PMSM Motor Co
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