AN2154/D: Low-Cost, 3-Phase, AC Motor Control System with
Contents
1. e Converts a sensed output voltage into a digital value e Calculates software regulator for feedback loop e Programs its PWM channel to create the pattern of the input current e Synchronizes using mains zero crossing detector operation to the mains frequency The interrupt handlers used for PFC operation are e The input capture interrupt handler on channel 0 timer A performs the synchronization for the PFC e The output compare interrupt handler generates the waveform of the input current e The A D interrupt handler performs the control of the PFC output voltage The flow diagram of the control PFC software is depicted in Figure 2 MOTOROLA Application Note START INITIALIZE WAIT FOR MAINS ZERO CROSSING SET TIMER WAIT FOR OUTPUT COMPARE SELECT MILESTONE BY POINTER Ba MILESTONE 1 MILESTONE 2 MILESTONE 3 MILESTONE 4 MILESTONE 5 PROGRAM PWM RESET POINTER i ACTIVATE INHIBIT MEASURE Vout REGULATOR PROGRAM PWM DEACTIVATE INHIBIT PROGRAM PWM INCREMENT POINTER Figure 2 PFC Control Software Flow Diagram AN2154 10 MOTOROLA Input Capture Interrupt Handler on TIMA Channel 0 AN2154 Application Note Software Design The desired shape of the input current is a non sine wave with stairs The number and size of the stairs is optimized to fulfill these requirements e Least com2. Figure 10 State Diagram READ_CONST Timeout AN2154 26 MOTOROLA AN2154 Application Note Software Design PI_CONST is accessed from the main software timer in PI_CONST rates The rates define the time constant of the PI controller The following sequence is performed see Figure 11 During deceleration the dc bus voltage is checked and in case of overvoltage the deceleration is interrupted until the capacitor is discharged When no deceleration overvoltage is measured the acceleration deceleration speed profile is calculated The actual motor speed is calculated It is based on the time measurement between two subsequent rising edges of the input capture The PI speed controller is performed and the corrected motor frequency is calculated The corresponding voltage amplitude is calculated according to the Volt per Hertz profile Thus both parameters for PWM generation are available Table_inc Amplitude MOTOROLA 27 Application Note OVERVOLTAGE PI_CONST TIMEOUT DECELERATION OVERVOLTAGE PROTECTION NO OVERVOLTAGE ACCELERATION DECELERATION RAMP AND PFC CONTROL TACHO SPEED CALCULATION PI SPEED CONTROLLER DONE DONE RETURN TO SCHEDULER Figure 11 State Diagram PI_CONST Timeout Fault Handling It is important to note that in the event of a system fault the software services the event in a timely manner It accommodates two fault inputs overcurre
3. START STOP switch FORWARD REVERSE switch speed potentiometer the speed command is calculated using an acceleration deceleration ramp The comparison between the actual speed command and the tachometer speed generates a speed error The speed error is passed to the speed PI controller generating a new corrected motor frequency The corresponding voltage is calculated using a V Hz ramp The PWM generation process calculates a system of 3 phase voltages representing the required amplitude and frequency including dead times The 3 phase PWM motor control signals are then output to the power stage The dc bus voltage and the dc bus current are measured during the control process They are used for overvoltage and overcurrent protection of the drive The overvoltage protection is performed by the software while the overcurrent fault signal utilizes a fault input of the microcontroller If any of the mentioned faults occur the motor control PWM outputs are disabled for drive protection and the system fault state is displayed These faults depending on the operating mode of the system are output to the LEDs on the controller and or the PC terminal that is connected to the control board The control algorithm of the close loop ac drive is described in Figure 5 It consists of processes that are described briefly in the subsections that follow For details refer to the application note A 3 Phase AC Induction Motor Control System Based on the MC
4. MR24_VHz_PFC PRM Parameter file containing the interrupt and reset vector addresses for the system s MR32 software For information regarding the PC Master software application note software and microcontroller documentation refer to www motorola com mcu Motorola s Web site for microcontrollers In this application note the design of a 3 phase ac speed controlled induction motor software is described with a special attention to power factor correction and optional PC Master communication Any hardware part of this system can be purchased from Motorola The toolset enables the MR32 to be evaluated in a system without the necessity of building prototype hardware The design described in this application note illustrates the efficiency and simplicity of using the MC68HC908MR32 microcontroller as the processing heart of a robust motor control system for low cost industrial and consumer motor control applications In addition Motorola application notes Low Cost 3 Phase AC Motor Control System Based on MC68HC908MR24 document order number AN1664 D and A 3 Phase AC Induction Motor Control System Based on the MC68HC908MR32 document order number AN1857 D give the reader a full view on the presented application software and hardware which can be found on Motorola Web pages MOTOROLA 31 Application Not Motorola reserves the right to make changes without further notice to any products herein Motorola makes no warranty
5. representation or guarantee regarding the suitability of its products for any particular purpose nor does Motorola 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 which may be provided in Motorola 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 Motorola does not convey any license under its patent rights nor the rights of others Motorola products are not designed intended or authorized for use as components in systems intended for surgical implant into the body or other applications intended to support or sustain life or for any other application in which the failure of the Motorola product could create a situation where personal injury or death may occur Should Buyer purchase or use Motorola products for any such unintended or unauthorized application Buyer shall indemnify and hold Motorola and its officers employees subsidiaries affiliates and distributors harmless against all claims costs damages and expenses and reasonable attorney fees arising out of directly or indirectly any claim of personal injury or death associated with such unintended or unauthorized use even if such c
6. benefit of the design is the possibility of easy modification of the system by software updates Motorola Inc 2001 intelligence everywhere Application Note System Concept The design is based on the conjunction of the ac induction motor control system with the digital power factor correction application Detailed ideas of the ac induction control design are described in the application note Low Cost 3 Phase AC Motor Control System Based on MC68HC Motorola order number AN1664 D This application note presents only basic facts concerning particular designs and it is focused primarily on the conjunction of both algorithms The system is driven by the Motorola 8 bit microcontroller MCU MC68HC908MR32 This MCU simultaneously performs PFC control and motor control The block diagram of the whole motor control system can be seen in Figure 1 BULK CAPACITOR 230 V MAINS INVERTERS O MICROCONTROLLER Figure 1 Block Diagram of the Motor Control System with PFC The MCU drives the boost PFC and through inverters it also drives a motor The microcontroller has built in interfacing peripherals Through input interfaces like analog to digital converters or port pins the MCU collects signals from sensors and converts these analog values into digital forms that are further processed by a control program As a result of the program the control parameters are converted through output interfaces like PWM ch
7. control algorithm keeps the magnetizing current flux of the motor constant by varying the stator voltage with frequency The ratio of voltage divided by the frequency is constant during the linear portion of the profile The commonly used volt per Hertz ramp profile of a 3 phase ac induction motor is illustrated in Figure 8 PHASE VOLTAGE A E POINT 100 PASERO BOOST 4 VOLTAGE BOOST BASE FREQUENCY rpm FREQUENCY FREQUENCY Figure 8 Volt per Hertz Ramp The volt per Hertz ramp is defined with these parameters e Base point Defined by the base frequency usually 50 Hz or 60 Hz e Boost Defined by the boost voltage and the boost frequency The ramp profile fits to the specific motor and can be easily changed to accommodate different ones The software function RAMP C provides the voltage calculation according to a V Hz ramp The input of this software function is the generated inverter frequency V_out The output of the function is the amplitude of the generated voltage Amplitude MOTOROLA 21 Application Note PWM Generation Parameters required by the PWM generation process are the output of this software function e Table increment Table_inc that corresponds to the frequency V_out is used to roll through the wave table for generation of the output inverter frequency e Amplitude of the generated inverter voltage The process of sine wave generation provides 3 phase sine waves e
8. dc bus brake IGBT and brake current limiting resistors e 3 phase bridge inverter six IGBTs e Individual phase and dc bus current sensing shunt resistors with Kelvin connections e Power stage temperature sensing diodes e IGBT gate drivers e Current and temperature signal conditioning e 3 phase back EMF voltage sensing and ZC zero crossing detection circuitry e Board identification processor MC68HC705JJ7 e Low voltage on board power supplies e Cooling fans AN2154 MOTOROLA Application Note Software Power Stage To operate properly the 3 phase ac induction drive control system with Jumper Settings PFC requires the JP201 jumper to be in the PFC position Software The system software includes three algorithms e 3 phase V Hz ac induction motor control algorithm e Digital power factor correction algorithm e PC Master communication routines The system software can be executed in the MMDS05 08 emulator system or in a programmed MC68HC908MR2z2 resident on a daughter board plugged into the control board The algorithms can be judged as independent and their software design and basic features can be described separately Basic features of the V Hz control software include e Controlled acceleration and deceleration e Speed in the range of 0 to 2400 rpm for 4 pole motor e The drive can run clockwise or counterclockwise e Speed is sensed by a tachometer generator e PWM frequency is 16 kHz e Operation in PC Master or m
9. given by the set PWM frequency and the selected PWM interrupt prescaler register named PCTL2 This process has to be repeated often enough compared to the wave frequency to generate the correct wave shape Therefore for a 16 kHz PWM frequency it is called every fourth PWM pulse Thus the PWM registers are updated at a 4 kHz rate for example every 250 us The processes described previously are implemented in a single state machine and are illustrated in Figure 9 Figure 10 and Figure 11 The general state diagram incorporates the main routine entered from reset and eight interrupt states The main routine includes the initialization of the microcontroller and a software timer for the control algorithm timebase The interrupt states provide calculation of actual speed of the motor overcurrent fault handler PWM generation process zero crossing interrupt for the PFC output compare to generate the input current waveform A D interrupt to control PFC output voltage SCI read and transmit routines A software timer routine provides the timing sequence for required subroutines The software timer is performed instead of an output compare interrupt handler The main program has several time demanding interrupt routines and more interrupt requirements can cause a software fault The software timer routine has two timed outputs e READ_CONST is a routine that scans inputs calculates the speed command handles fault routines and the
10. input current waveform The variable Point is used to determine the next step During each step the next output compare on channel 1 is programmed and a proper input current level is set by programming the duty cycle of timer B PWM duty cycle When step 2 Point 2 is reached the ADC conversion on channel 1 is started It senses the dc bus voltage and the ADC conversion complete interrupt is enabled When the last step Point 5 is reached the output compare on TIMA channel 1 is disabled and the input capture on channel 0 is enabled ZC synchronization The position of the milestones on the inductor current can be seen from Figure 4 848 us 511 us 282us 411 us 4398 us 4398 us lt gt lt gt ast a gt lt a t l l l 4 ZC ZC 1 START SIGNAL FROM ZCD Figure 4 Milestones of Induction Current The PFCcntr1 function is called to service the interrupt The sensed dc bus voltage is stored into variable Out_volt_new ADC interrupts are disabled and ADC conversion on channel 0 is started for the required speed sensing During initialization the algorithm jumps to the feedback loop offset calibration routine When the offset is found the CALIB_OFFSET flag in the PFC_status status word is cleared and the LOAD_ON_FLG flag in the Mcs_status status word is set Once the CALIB_OFFSET flag is cleared the calibration routine is skipped in the next algorithm execution The sensed voltage is fed into the regulator
11. s application present its block diagram show graphically the status of variables and many other features that can be extended by the user A small program is resident in the MR82 that communicates with the PC Master software to parse commands return status information to the PC and process control information from the PC The actions controlled by the PC Master are e Start Stop control e Motor speed setpoint e Reset the drive system e Motor rotation direction control clockwise counter clockwise CW CCW MOTOROLA 13 Application Note The following are default variables read by the PC Master software and displayed to the user e Required speed e Actual motor speed e dc bus voltage e Power module temperature e Display system status and error flags The PC Master commands are described in Table 2 Table 2 PC Master Commands Command Command Code Demo Suitcase Action Set manual mode 00 Setting of manual mode Set PC master mode 01 Setting of PC master mode The status and error flags are read by the PC Master in 1 s periods The flags are used to determine the status of the operation of the software by the PC Master application AN2154 14 MOTOROLA Drive Operating Modes AN2154 Application Note Software Design Descriptions of the control status and failure flags are found in Table 3 Table 3 PC Master Status and Error Flags Register Bit No D
12. 68HC908MR32 Motorola document order number AN1857 D It can be found on Motorola s Web pages MOTOROLA 17 Application Note SWITCHES START STOP A D CONVERTERS FORWARD REVERSE OPERATION MODE JUMPER PROCESS p SPEED COMMAND PROCESS LED CONTROL TACHO IC Out_volt_new V_command PROCESS SPEED SENSOR PROCESS ACCELERATION DECELERATION RAMP V_tacho GF_FLAG 7 V_com_actual PROCESS PI CONTROLLER PROCESS Vout FAULT CONTROL OC FAULT PCTL1 PROCESS V Hz RAMP Amplitude Table_inc PVAL1 PVAL3 PVAL5 Figure 5 Data Flow Diagram AN2154 18 MOTOROLA AN2154 Application Note Software Design The measured dc bus voltage is represented by the variable Out_volt_new The input value from the speed potentiometer is labeled Pot_voltage The input parameters of the process are evaluated and the speed command v_command is calculated accordingly The general fault GF_F LAG is analyzed and the state of the drive is set The drive state diagram is shown in Figure 6 The state of the LEDs is controlled according to the system status The calculated speed command v_command is a 2 byte variable where the first byte is integer and the second byte is remainder for instance 1 0 Hz 0x0100 The upper byte represents the integer portion and the lower byte represents the fractional portion of the value This format is kept throughout the program for all speed variables Th
13. LED driver e PI_CONST isa routine that provides overvoltage protection during deceleration speed ramp acceleration deceleration PI controller and V Hz ramp and provides parameters for PWM generation MOTOROLA 23 Application Note The interrupt handlers have following functions The input capture IC interrupt handler reads the time between two subsequent IC edges basic part of the process speed sensor The fault interrupt handler takes care of overcurrent fault interrupt overcurrent part of the process fault control The PWM interrupt handler generates a system of 3 phase voltages for the motor process PWM generation The input capture interrupt handler on channel 0 of timer A makes the synchronization for the PFC The output compare OC interrupt handler generates the waveform of the input current The A D interrupt handler performs the control of the PFC output voltage The SCI read interrupt handler services receive interrupts for the PC Master communication routines The SCI transmit interrupt handler services transmit interrupts for the PC Master communication routines AN2154 24 MOTOROLA AN2154 Application Note Software Design INPUT CAPTURE INTERRUPT SPEED RESET INPUT CAPTURE INTERRUPT PFC ZC INPUT CAPTURE INTERRUPT HANDLER INPUT CAPTURE INTERRUPT HANDLER INITIALIZE SOFTWARE DONE DONE FAULT INTERRUPT E OUTPUT COMPARE INTERR
14. Order this document by AN2154 D MOTOROLA ste digital dna Semiconductor Products Sector AN2154 Application Note Low Cost 3 Phase AC Motor Control System with Power Factor Correction Based on MC68HC908MR32 By Petr Stekl and Zdenek Kubiczek Motorola Czech System Application Laboratory Roznov pod Radhostem Czech Republic Introduction This application note describes the design of a 3 phase ac induction motor drive with digital power factor correction PFC on a single low cost microcontroller the MC68HC908MR32 MR32 Most usual variable speed ac induction motor drive designs contain a full bridge rectifier and a large dc bus capacitor at the input Such a circuit draws a peak current from the wall socket which provokes a high content of harmonics The low power factor PF as described in the present circuit reduces the necessary power from the mains and increases the efficiency of the mains supply network The international standard IEC1000 3 2 defines the limits of the harmonic content of the input current for mains supplied equipment To meet the norms the design requires a power factor correction at the input The present design allows simultaneous driving of the power factor correction algorithm and the ac induction motor This way significant cost reductions of the design can be achieved Moreover a wide range of input voltages from 90 volts to 265 volts ac and regulation of dc bus voltage can be achieved Another
15. The nominal dc bus output voltage is set to 375 Vdc The required output voltage is determined by the Out_Volt_Max variable The output of the AN2154 12 MOTOROLA PC Master Communication AN2154 Application Note Software Design voltage regulator is the amplitude of the input inductor current The calculated input current is limited to the maximum input value and zeroed if negative The new value of the variable Curr_level1 variable is derived representing the higher level of the input current and the new value of the variable Curr_level2 variable is calculated for lower level of the input current The PC Master Communication is a program resident in the MR32 that communicates via the SCI serial communications interface with the PC Master software to parse commands return status information to the PC and process control information from the PC The MR32 features are assigned to the algorithm as follows The PC Master Communication software is intended to be used as an aid in developing the motor control software When using the PC Master software all of the required actions of the motor control software are manipulated by the operator The PC Master software executes on a PC that is connected to the isolated RS232 serial port on the control board The PC Master software user interface displays various sets of views tabs programmed in HTML code with embedded objects and scripts They are used to control the board
16. UPT FAULT INTERRUPT HANDLER OUTPUT COMPARE INTERRUPT READ_CONST HANDLER SOFTWARE TIMER PWM INTERRUPT TIMEOUT ADC INTERRUPT ADC INTERRUPT HANDLER PWM INTERRUPT HANDLER aoe E TRANSMITTER INTERRUPT SCI RECEIVER deaa SCI TRANSMITTER o RUT INTERRUPT HANDLER HANDLER ao DONE Figure 9 State Diagram General Overview READ_CONST is accessed from the main software timer in READ_CONST rates The following sequence is performed See Figure 10 e All inputs are scanned speed pot START STOP switch FORWARD REVERSE switch temperature dc bus current The dc bus voltage is measured in the A D interrupt routine e The speed command is calculated according to the operational mode e The dc bus voltage is compared with the overvoltage limit and the overcurrent flag is checked e Incase of a fault condition the fault recovery routine is entered and until the recovery time expires the drive remains disabled MOTOROLA 25 Application Note e Finally the LED driver controls individual LEDs according to the status of the drive e The PFC hardware is enabled disabled according to the drive status e PC Master commands are serviced READ_CONST TIMEOUT OPERATING MODE DISTRIBUTION PC MASTER OPERATING MODE MANUAL OPERATING MODE FAULT DETECTION RUN ENABLE FAULT RECOVERY FAULT RECOVERY LED DRIVER RETURN TO SCHEDULER
17. V_tacho A software filter for the speed measurement can be incorporated in the process for better noise immunity In this case the actual motor speed is calculated as an average value of several measurements The general principle behind a PI control loop is shown in Figure 7 The speed closed loop control is characterized by the measurement of the actual motor speed This information is compared with the reference setting point and an error signal is generated The magnitude and polarity of the error signal corresponds to the difference between the actual and the required speed Based on the speed error the PI controller generates the corrected motor frequency for the error compensation and reaches the required motor speed This PI process takes these two input parameters actual speed command V_com_actual and actual motor speed measured by a tachogenerator V_tacho Then it calculates the speed error and performs the speed PI control algorithm The output of the PI controller is a new frequency of the fundamental sine wave that is to be generated by the inverter V_out REFERENCE SPEED SPEED CORRECTED SPEED V_com_actual ERROR P CONTROLLER V_out ACTUAL MOTOR SPEED V_tacho CONTROLLED SYSTEM Figure 7 Closed Loop Control AN2154 20 MOTOROLA Volt per Hertz Ramp Implementation AN2154 Application Note Software Design The drive is designed as a constant Volt per Hertz drive This means that the
18. ach shifted by 120 degrees relative to each other The sine waves can be pure sine waves or they can have a third harmonic component The calculation is based on the wave table stored in the MCU s ROM The table describes either a pure sine wave or a sine wave with an additional third harmonic The second case is often preferred because it allows the generation of the first harmonic sine voltage equal to the input ac line voltage Because of quarter wave symmetry only the first quadrant of the wave period is stored in the table The wave values for other quadrants are calculated from the first one The data format of the stored wave table is from 0x00 for 0 voltage up to PWM modulus 2 for 100 percent voltage Thus the proper data scaling is secured For a detailed process description of PWM refer to the application note AN1857 A 3 Phase AC Induction Motor Control System Based on the MC68HC908MR22 that can be found on the Motorola Web pages The input parameters of the process are e The table increment Table_inc updates the wave pointer e Amplitude of the generated inverter voltage The output parameters of the process are e PWM value for phase A PVAL1 register e PWM value for phase B PVALS register e PWM value for phase C PVAL5 register AN2154 22 MOTOROLA General Application Overview AN2154 Application Note Software Design The process of setting these registers values is accessed regularly in the rate
19. and V Hz ramp state appropriately PWMCALC C Contains code to service the PWM interrupts which ultimately generate the sine outputs to the power stage RAM C Contains the global RAM variable definitions for MR32 system software RAMP C Contains code for acceleration and deceleration ramp state V Hz ramp state SPEED C Contains the READ_CONST code scan inputs state operational mode distribution state speed calculation manual operational mode state speed calculation PC Master operation mode state fault detection state run enable state fault recovery state LED driver state PFC enable disable logic TACHO C Contains timer A channel 0 interrupt code that calculates the time between tachometer interrupts 3RDHQUAD H Header file that contains a 256 word 1 quadrant sine table with third harmonic injection CODE_FUN H Header file containing the prototypes of the external functions for V Hz control CONST H Header file that contains the global system constants definitions for system s MR32 software MR_IDENT H Contains PCB board type identification constants MR2410 H Provides the MR24 MR32 registers map PCMASTER H Contains the PC Master SCI communication constant and variables declarations AN2154 30 MOTOROLA References Conclusion AN2154 Application Note Conclusion RAM H Header file that contains global RAM variable declarations for MR32 system software
20. annels digital to analog converters or port pins into control signals which drive the PFC and the ac induction motor AN2154 MOTOROLA System Hardware System Specifications MR32 Control Board AN2154 Application Note System Hardware The present design can help a user start the development of his own system according to his particular requirements It can save much engineering time and speed up time to market The system hardware consists of the following equipment MR32 control board Optoisolation board 3 phase high voltage ac BLDC brushless dc power stage board 180 W ac induction motor with speed sensor 12 to 15 V dc power supply 110 V 60 Hz ac or 230 V 50 Hz ac power supply wall socket The printed circuit boards PCB and the user s manuals are available from Motorola Table 1 System Specifications Nominal input voltage 90 265 V rms Input voltage frequency 50 60 Hz Maximum input current 2 3 Arms Maximum electrical output power 550 W Maximum dc bus voltage 400 V Output phase voltage 0 230 V rms Output voltage frequency 0 100 Hz For a more detailed description of the MR82 control board refer to Motorola Embedded Motion Control MC68HC908MR32 Control Board User s Manual Motorola document order number MEMCMR32CBUM D that comes with the board kit number ECCTR908MR32 MOTOROLA Application Note The control board is designed to be used as an aid for hardwar
21. anual operating mode e Overvoltage and overcurrent protection Basic features of the PC Master communication software include e Ability to read write any RAM variable e Ability to read any ROM variable e Execution of PC Master commands Basic features of the power factor correction software include e Automatic input voltage detection 110 V 60 Hz and 230 V 50 Hz e dc bus voltage regulation e Overvoltage and overcurrent protection AN2154 MOTOROLA 7 Application Note Software Design In this section the design of particular applications is described first separately and then the overall functionality is described Initilization The main routine provides initialization of the microcontroller Clears RAM Initializes PLL clock Initializes PWM module Center aligned complementary PWM mode positive polarity MOR register COP and LVI enable MOR register PWM modulus defines the PWM frequency PMOD register 2 us dead time DEADTM register PWM interrupt reload every fourth PWM cycle PCTL2 register FAULT2 overcurrent fault in manual mode interrupt enabled FCR register Sets up I O ports Initializes timer A for input capture IC output compare OC and for software timer reference Initializes timer B for PWM generation of the PFC Initializes the A D analog to digital converter Detects connected boards Detects input line voltage limits Detects input line frequency Calibrates t
22. ase ac induction drive control system with PFC requires the following jumper settings of the MR32 control board e JP1 closed Speed sensor tacho e JP4 closed PFC zero crossing signal e JP5 closed PFC PWM signal e JP2 and JP3 open The software is independent of the DIP switch settings The function of the optoisolation board is to provide a galvanic isolation barrier between the control board s input outputs I O both analog and digital parts and the high voltage system power board s I Os These isolated signals to and from the optoisolation board are connected via two 40 pin ribbon cables The pin assignment for both connectors is the same The signal flow through the optoisolation board in both directions is a one to one relation of its source For a more detailed description of the optoisolation board refer to Motorola Embedded Motion Control Optoisolation Board User s Manual Motorola document order number MEMCOBUM D The power requirement for the control board s circuitry is satisfied with a single external 12 to 15 volt dc power supply It can be connected to the optoisolation board either via connector JP1 labeled Ext Power 12V DC or power jack J3 Either one but not both may be used This power supply is fed to the control board through the 40 pin ribbon cable connector The excitation for the power stage side circuitry is supplied to the power stage through the 40 pin output connector located o
23. e and software design for single 3 phase permanent magnet brush or brushless dc motor drive applications It does not contain the MC68HC908MR32 microcontroller The control board is designed to be directly connected to an MR32 EVM board which is a part of an MMDS MMEVS emulation system connected via an impedance matched ribbon cable A daughter board is designed to house the MR32 microcontroller and will plug into the control board in place of the emulator cable With the daughter board plugged into the control board standalone operation of the system is possible The features of the control board include e Six motor control PWM pulse width modulation outputs with LED light emitting diode indicators e Speed control potentiometer e Optoisolated half duplex RS232 interface e START STOP and FORWARD REVERSE switches e Hall effect inputs for brushless dc motor control e Back EMF electromotive force inputs for brushless dc motor control e Configuration jumpers e 2 position DIP dual in line package switches for user option control e Emulator daughter board connectors e Processor reset switch e Two system fault inputs e Nine analog inputs e Three software controlled LEDs e On board regulated power supply e Motor I O input output interface via a ribbon cable connector AN2154 4 MOTOROLA MR32 Control Board Jumper Settings Optoisolation Board AN2154 Application Note System Hardware The 3 ph
24. e system software calculates a new speed based on the requested speed according to the acceleration deceleration ramp RESET STAND BY MCS STATE V_command lt gt 0 GENERAL FAULT RECOVERY 0 START STOP 1 PWM DISABLED FAULT RECOVERY MCS STATE V_command 0 START STOP 1 RUN MCS STATE PWM DISABLED GENERAL FAULT 0 START STOP 0 PWM ENABLED FAULT MCS STATE PWM DISABLED V_command 0 STOP MCS STATE V_out 0 PWM DISABLED OVERVOLTAGE OVERCURRENT Figure 6 Drive State Diagram MOTOROLA 19 Application Note Drive Deceleration Speed Control Loop During deceleration the motor can work as a generator In the generator state the dc bus capacitor is charged and its voltage could easily exceed its maximal voltage Therefore the dc bus voltage is measured and compared with a limit In case of a deceleration overvoltage the deceleration is interrupted and the motor runs with a constant speed to discharge the capacitor down to an acceptable value Deceleration can then continue During deceleration depending on the input line voltage the dc bus voltage controlled by the PFC is maintained below 340 volts The speed sensing process utilizes the MR32 s input capture interrupt function The input capture interrupt reads the time between the rising edges of the speed sensor s output and calculates the actual motor speed
25. escription 0 0 Stop the motor 1 Start the motor P 0 Forward direction Motor_Ctrl 1 Reward direction 2 6 Reserved 7 0 Clear the bit clear the error 0 0 START STOP switch set to stop flag 1 START STOP switch set to start flag 0 Motor is stopped 1 1 Motor is running Motor_Status 2 Reserved 3 0 230 V line detected 1 120 V line detected 4 7 Reserved 0 1 Overcurrent failure 1 1 Overheating failure Failure 2 1 Overvoltage failure 3 7 Reserved The motor drive is able to operate in the following two operating modes OM The MANUAL PC Master OM option is set by the PC Master command when the START STOP switch is in the STOP position The motor stops and the green LED is off It is confirmed by hardware after the START STOP switch has been set to the START position e MANUAL Operating Mode Default mode after reset In the MANUAL OM the required action is set by switches mounted on the control board START STOP FORWARD REVERSE and a potentiometer Speed The status of the drive is displayed by LEDs MOTOROLA 15 Application Note PC Master Operating Mode Required software actions on motor drive are controlled by the PC Master commands running on the PC connected to the control board The motor can be stopped in case of emergency by setting the START STOP switch to the STOP position The actions controlled by the PC Master control page are Start stop
26. he PFC feedback offset FB_offset If any error occurs the fault LED is turned on the failure register is set and the software waits for reset Enables interrupts When the MR32 is reset the software configures the various system I O the FORWARD REVERSE switch and the START STOP switch The dc bus voltages are checked and the speed potentiometer s value is AN2154 MOTOROLA Power Factor Correction AN2154 Application Note Software Design input The yellow LED of the control board is illuminated when the system is ready Afterward the identification of the connected boards for example optoisolation and power boards is checked The default operation mode is set to manual The PC Master operation mode can be set by the PC Master command The PFC algorithm is initialized When it is passed the fault flag Failure is tested for any system fault Anytime a fault is detected in the system the red LED of the control board is turned on The status of the LEDs is described later in this application note The PFC algorithm drives the analog part of the PFC The MR32 features are assigned to the algorithm as follows e Timer A input capture TCHOA pin ZC detection e Timer B channels 0 and 1 TCHOB pin Buffered PWM signal generation e Analog to digital converter channel 2 ATD2 pin dc bus voltage sensing e input output port A PTAO pin PFC inhibit signal The control algorithm performs these tasks
27. laim alleges that Motorola was negligent regarding the design or manufacture of the part Motorola and amp are registered trademarks of Motorola Inc Motorola Inc is an Equal Opportunity Affirmative Action Employer How to reach us USA EUROPE Locations Not Listed Motorola Literature Distribution PO Box 5405 Denver Colorado 80217 1 303 675 2140 or 1 800 441 2447 JAPAN Motorola Japan Ltd SPS Technical Information Center 3 20 1 Minami Azabu Minato ku Tokyo 106 8573 Japan 81 3 3440 3569 ASIA PACIFIC Motorola Semiconductors H K Ltd Silicon Harbour Centre 2 Dai King Street Tai Po Industrial Estate Tai Po N T Hong Kong 852 26668334 Technical Information Center 1 800 521 6274 HOME PAGE http Awww motorola com semiconductors Motorola Inc 2001 A MOTOROLA AN2154 D
28. n the optoisolation board In addition to usual motor control signals an MC68HC705JJ7 microcontroller serves as a Serial link It allows the controller board s software to identify the configuration of the optoisolation board and the power stage board It passes configuration information to the control board for processing and checking the system configuration MOTOROLA Application Note Power Stage For a more detailed description of the 3 phase ac BLDC high voltage power stage and for board setup refer to Motorola Embedded Motion Control 3 Phase AC BLDC High Voltage Power Stage User s Manual Motorola document order number MEMC3PBLDCPSUM D The power stage provides a high power drive circuitry for various types of motors It is suitable for driving ac induction permanent magnet brush and brushless dc motors The power stage consists of a set of two printed circuit boards One of the PC boards is a power module containing the power IGBTs isolating gate bipolar transistor a brake IGBT a power factor corrector field effect resistor FET and temperature sensing diodes The second PC board contains IGBT drive circuits analog signal conditioning low voltage power supplies power factor control circuitry and an MC68HC705JJ7 microcontroller used for board configuration and identification The features of the power stage include e 1 phase bridge rectifier e Power factor switch and diode e Power factor correction coil e
29. nt and overvoltage Overcurrent The external hardware provides a rising edge on the fault input of the microcontrollers FAULT2 input through the fault generation circuit This signal disables all motor control PWM s outputs PWM1 PWM6 and sets the general fault flag GF_FLAG Also the OVER_CURRENT flag is set in the Failure register used by the PC Master control interface AN2154 28 MOTOROLA Software Files AN2154 Application Note Software Design e Overvoltage The sensed dc bus voltage is compared with a limit within the software In case of overvoltage all motor control PWM outputs are disabled by the software which sets bits in the MCU s PWM control register PCTL1 and sets a bit in the general fault flag GF_FLAG Also the OVER_VOLTAGE flag is set in the Failure register used by the PC Master control interface The overvoltage fault is set only if the motor is braking in generator mode In motor mode the motor supplies power to the load if an overvoltage occurs the PFC is disabled the overvoltage failure is not detected and the motor is not blocked It is important to note that the PFC output voltage operates very close to 400 volts which is the overvoltage limit The regulation overshoot would cause an overvoltage failure when PFC is running Therefore the overvoltage is blocked when the PFC is running If any of these faults occur the fault LED will flash The system remains disabled until the faul
30. plex to avoid overloading of the microcontroller e Harmonic currents content complies with standard IEC1000 3 2 The waveform of the input current consists of two current levels and five time intervals per half period time range The generated current waveform is shown in Figure 3 Ses Sire et E eed eS eh ee Seat Se HS el es ce 1 E ec ees es ee es Se es fet INPUT CURRENT A oO 0 00 0 01 0 02 Figure 3 Input Current for 1 kW Output Power After initialization the PFC software waits for the mains zero crossing ZC signal which is used for synchronization of the PFC algorithm with the line voltage The PFCzc function is called to service the interrupt The output compare channel 1 is programmed for the first input current waveform milestone The programmed value corresponds to 848 us time interval Output compare interrupts on channel 1 are enabled The input capture detection ZC signal is disabled for better noise immunity If the PFC disable flag in PFC_status status word is set for example overvoltage was detected the PFC output is disabled for the next half period The COP is serviced here as well MOTOROLA 11 Application Note Output Compare Interrupt Handler on TIMA Channel 1 ADC Conversion Complete Interrupt Handler Channel 1 The PFCwave function is called to service the interrupt The main task of this function is to define the input current waveform milestones time intervals and hence form the
31. t is cleared by switching the START STOP switch to the STOP and then to the START position or cleared by the PC Master by setting the bit ERROR_CLEAR_PMFLG in control register Motor_Ctr1 As soon as the START STOP switch is set to START the motor restarts The software consists of the following parts Code_ISR C Contains the interrupt and reset vector addresses for the system s MR82 software DigitPFC C Contains the software used to drive the power factor correction hardware resident on the power board The software sets the duty cycle of timer B channel 0 that pulse width modulates the power board s PFC input hardware at 125 kHz FAULT C Contains the fault interrupt service routine MAIN C This is the entry point following a reset and after initial startup code It contains the initialization software state code the main state machine with the software timer state code MOTOROLA 29 Application Note MR_IDENT C Contains code that communicates with the MC68HC705JJ7 microcontrollers resident on the optoisolation and power boards The resulting information from this routine is used for configuration checking and input to system run time parameters PCMASTER C Contains the PC Master SCI communication routines PI C Contains the PI_CONST timeout code deceleration overvoltage protection state tacho speed calculation state PI speed controller state and calls acceleration deceleration ramp state
32. the motor Control the speed Reset the drive Drive direction The variables read by the PC Master control page as default will be Required speed Actual motor speed dc bus voltage Power module temperature Read the status and error flags of the software Any other variable can be read written LEDs Status The software uses active high indicators connected to the MCU pins and configured as outputs according to the following description Motor running LED green PTC6 MCS status is Run otherwise the LED is off Status LED yellow PTC5 MCS status is Stand_By or Fault LED is turned off MCS status is Run or Stop LED is turned on Fault LED red PTC4 MCS status is Stand_By Run or Stop LED is turned off MCS status is Initialization Error LED is turned on MCS status is Fault overvoltage overcurrent LED is flashing with a frequency of 0 5 Hz Otherwise the LED 1 2 and 3 are turned off AN2154 16 MOTOROLA Brief V Hz Algorithm Description AN2154 Application Note Software Design The motor control software monitors the state of the sensors as they are periodically scanned in the software timer loop The speed of the motor is calculated utilizing the input capture interrupt The green LED of the control board will illuminate whenever the motor is running According to the operational mode setup and state of the control signals
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