Dual Motor Control application
Contents
1. Freescale Semiconductor Application Note Document Number AN4407 Rev 0 2011 Dual Motor Control for PMSM with the Kinetis K70 by Pavel Rech Systems Application Engineer Microcontroller Solutions Group 1 Introduction This application note deals with the field oriented control FOC of two permanent magnet synchronous motors PMSM with the Kinetis K70 microcontroller MCU A dual motor control application requires a processor with high performance and the right set of peripherals for simultaneous control of two motors The Kinetis K70 MCU satisfies both the requirements with a performance margin for the application code The theoretical aspects of the dual motor control as well as a short introduction to all the hardware parts and their realization possibilities on the new K70 processor are included in this application note 2011 Freescale Semiconductor Inc o nu A un A WwW Contents EEES OTET P ae ete TAE E ern Kinetis portfolio and K70 family SDa E A E e SF Pg Z freescale Kinetis portfolio and K70 family overview Figure 1 Dual motor control demo with K70 MCU 2 Kinetis portfolio and K70 family overview Kinetis MCU is based on the ARM Cortex M4 core It gives the Kinetis portfolio a unique position among similar MCUs The Kinetis portfolio consists of five MCU families with over 200 pins peripherals and software compatible devices The features of the Kinetis MCU families ca2. ARCO Tower 15F 1 8 1 Shimo Meguro Meguro ku Tokyo 153 0064 Japan 0120 191014 or 81 3 5437 9125 support japan freescale com Asia Pacific Freescale Semiconductor China Ltd Exchange Building 23F No 118 Jianguo Road Chaoyang District Beijing 100022 China 86 10 5879 8000 support asia freescale com For Literature Requests Only Freescale Semiconductor Literature Distribution Center 1 800 441 2447 or 1 303 675 2140 Fax 1 303 675 2150 LDCForFreescaleSemiconductor hibbertgroup com Document Number AN4407 Rev 0 2011 Information in this document is provided solely to enable system and software implementers to use Freescale Semiconductors products There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document Freescale Semiconductor reserves the right to make changes without further notice to any products herein Freescale Semiconductor makes no warranty representation or guarantee regarding the suitability of its products for any particular purpose nor does Freescale Semiconductor assume any liability arising out of the application or use of any product or circuit and specifically disclaims any liability including without limitation consequential or incidental damages Typical parameters that may be provided in Freescale Semiconductor data sheets and or specifications can and do vary in d
3. algorithm in order to utilize the processor processing time properly Also the overlay enables a decrease in current stress of the DC bus capacitors due to which the current peaks are spread Dual Motor Control for PMSM with the Kinetis K70 Rev 0 2011 Freescale Semiconductor Inc 7 Timing Ho eL LALA H in rt a a fh ESES ai hey a nu RO K 2 KX XK Processing time motor 0 time Processing time total KX OK OK OO HO OOK OX A eos O l O Free time for time Current control loop other processes conversion time e The interrupt instant Figure 4 Dual motor control timing Dual Motor Control for PMSM with the Kinetis K70 Rev 0 2011 Freescale Semiconductor Inc Hardware of dual motor control 7 Hardware of dual motor control The tower system is a valuable asset of Kinetis MCUs It is not possible to supply the motor from the MCU pins due to the voltage and current limitations therefore a full bridge consisting of powerful semiconductors is typically used to supply the motor Freescale offers a low level voltage power stage for the tower kits This power stage not only includes the MOSFET power devices but also a driver for the devices measurement circuits a protection unit and power supply This power stage fits the tower kit and thus a tower system including the power stage can be easily built The K70 MCU tower does not have natural support for dual motor control A new tower in
4. bit digital to analog converters DAC programmable gain amplifiers PGA high speed comparators CMP and an internal voltage reference e Connectivity and Communications e UART IrDA I2S CAN I2C USB and DSPI support e Timing and Control Powerful FlexTimer FTM e Periodic interrupt timer PIT e Programmable delay block PDB e System e 5 V tolerant general purpose input output GPIO with pin interrupt functionality e Operational in 1 71 3 6 V voltage range and 40 105 C temperature range e 256 pin MAPBGA package with 17x17 mm dimensions 4 Dual motor control K70 The dual motor control algorithm controls two motors in parallel The K70 MCU has only one core therefore it executes the algorithm for the first and the second motor alternately It reads the phase currents of each motor and detects the voltage of both inverters and according to user interface it generates the pulse width modulation PWM signals of both inverters The application requires the correct set of MCU peripherals For current and voltage measurement ADCs are needed At least two ADCs are required because for each motor the control needs to measure two phase currents in parallel Typically shunt sensors are used The measurement must be synchronized with the PWM pulses For this purpose the Kinetis family has a PDB which synchronizes the ADC with the FTM and provides various delays between them See Figure 2 After the necessary delay it runs the con
5. SFET driver selects communications 12C 2 channels SDHC 1 channel USB 1 channel CAN 2 channel Ethernet 1 channel 5 Control algorithm The dual motor control requires running two motor control algorithms in parallel Figure 3 shows the field oriented control FOC principle of a PMSM The key to FOC is to control the motor torque and field excitation or the motor magnetic flux independently and separately The operating principles of the two control loops are discussed below e The current control loop The following steps describe the working of this control loop a The two phase currents must be measured in the stator three phase system of coordinates b The current vector in the stator two phase system of coordinates can be obtained using the Clark Transformation c The following Park Transformation rolls the current vector into a rotating two phase system of coordinates according to the measured rotor position d The differences between the measured and required current components are forced into the proportional integral PI controller e The voltage components obtained from the controllers must be again rolled using the Inverse Park Transformation f The three components of the phase voltages for the PWM modulator are generated using the Space Vector Modulation block e The speed control loop It is less complex and determines the deviation between the required speed and the real rotor speed calculated from the ro
6. ifferent 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 Semiconductor does not convey any license under its patent rights nor the rights of others Freescale Semiconductor 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 failure of the Freescale Semiconductor product could create a situation where personal injury or death may occur Should Buyer purchase or use Freescale Semiconductor products for any such unintended or unauthorized application Buyer shall indemnify Freescale Semiconductor 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 claims alleges that Freescale Semiconductor was negligent regarding the design or manufacture of the part RoHS compliant and or Pb free versions of Freescale products have the functionality and electrical characteristics as their non RoHS complaint and or non Pb free counterparts For further information see http www freescale com or contact your F
7. ignals decoding for the first motor Quadrature encoder signals decoding for second motor FTM4 8 channels 6 channels Generation of 6 PWM channels for the second motor PDB 4 channels for 2 channels triggering 4 ADCs Two channels are multiplexed with two FTMs Triggering 2 ADC channels for phase currents measurement 2 channels for DAC triggering 4 channels for CMP triggering Analog ADC ADC1 32 channels 4 single ended including 28 single channels ended and 4 differential channels 3 channels for phase current and 1 for DC bus voltage measurements of the first motor ADC2 32 channels 4 single ended including 28 single channels ended and 4 differential channels 3 channels for phase current and 1 for DC bus voltage measurements of the second motor ADC3 32 channels including 28 single ended and 4 differential channels ADC4 32 channels including 28 single ended and 4 differential channels CMP 4 channels DAC 2 channels Table continues on the next page Dual Motor Control for PMSM with the Kinetis K70 Rev 0 2011 Freescale Semiconductor Inc o1 Control algorithm Table 1 Kinetis K70 peripherals overview for dual PMSM FOC continued Submodule and Used in the Purpose channels available application Communications UART 6 channels 1 channel FreeMASTER communication SPI 3 channels 1 channel with 2 chip MO
8. n be summarized as follows e Each family offers excellent performance memory and feature scalability with common peripherals memory maps and packages providing easy migration both within and between families e Kinetis MCUs are built from Freescale s innovative 90 nm Thin Film Storage flash technology with the unique FlexMemory e Kinetis MCU families combine the latest low power innovations and high performance high precision mixed signal capability with a broad range of connectivity human machine interface and safety and security peripherals e Kinetis MCUs are supported by a market leading enablement bundle from Freescale and numerous ARM third party ecosystem partners Dual Motor Control for PMSM with the Kinetis K70 Rev 0 2011 2 Freescale Semiconductor Inc BE E Kinetis K70 3 Kinetis K70 The latest family member the Kinetis K70 has a high performance rich peripheral integration and large internal memory From a motor control perspective the K70 MCU enables two high end motor control algorithms to run in parallel and a set of peripherals namely the FlexTimer and analog to digital converters ADC enables an interface to the motor control power electronics Here is a summary of the features of the Kinetis MK70FNIMOVMJ12 MCU e Core e ARM Cortex M4 Core Floating point unit e CPU frequency 120 MHz e Memory e 1 MB flash 128 KB RAM 16KB Cache e Mixed signal analogue e Fast high precision 16 bit ADC 12
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10. terconnect board was proposed to connect selected signals from the secondary and the primary elevator into the connector where the second power stage is inserted Both power stages can be supplied independently from their own sources or it is possible to connect to one power supply through DC buses in which case the motors can change energy mutually 8 References e K70 Sub Family Reference Manual available at http www freescale com e TWR MC LV3PH User s Manual available at http www freescale com e 3 Phase BLDC Motor Control on Kinetis User s Guide available at http www freescale com e PMSM Vector Control with Quadrature Encoder on Kinetis DRM available at http www freescale com Dual Motor Control for PMSM with the Kinetis K70 Rev 0 2011 Freescale Semiconductor Inc 9 How to Reach Us Home Page www freescale com Web Support http www freescale com support USA Europe or Locations Not Listed Freescale Semiconductor Technical Information Center EL516 2100 East Elliot Road Tempe Arizona 85284 1 800 521 6274 or 1 480 768 2130 www freescale com support Europe Middle East and Africa Freescale Halbleiter Deutschland GmbH Technical Information Center Schatzbogen 7 81829 Muenchen Germany 44 1296 380 456 English 46 8 52200080 English 49 89 92103 559 German 33 1 69 35 48 48 French www freescale com support Japan Freescale Semiconductor Japan Ltd Headquarters
11. tor position The PI controller processes the deviation and creates the required torque current component The field weakening is not implemented therefore the required flux current component is kept at zero A detailed description of the PMSM vector control application can be found in PMSM Vector Control with Quadrature Encoder on Kinetis Design Reference Manual DRM available at http www freescale com Dual Motor Control for PMSM with the Kinetis K70 Rev 0 2011 Freescale Semiconductor Inc O Timing Dual vector control with Kinetis K70 Gan Gan nena _ Fistrsm vector control e second pst vector control _ First PMSM vector control Second PMSM vector control vector control Inv Park Trans PWM Outputs Required Speed Q PI controller Measured Speed Park Trans ClarkTrans Speed Quad Encoder Calculation Timer signals Figure 3 Vector control block diagram 6 Timing The timing is the key for all motor control applications The timing determines how the processor performance is utilized For dual motor control the processes for individual motors must overlap It is convenient to set up the FTMs so that the first FTM overflow will happen exactly in the middle of the second FTM cycle See Figure 4 This gives the same processing time for the fast loops of the first and second motors so each motor has an available window equal to 50 of the total CPU time It is important to prepare such a control
12. version of the two phases currents in parallel This sequence runs alternately for the first and the second motor The current measurement is a hardware process running without code See Figure 4 on how it works Each motor is supplied by its own inverter whose power part is a full bridge Six PWM signals control the power devices in a full bridge Therefore two FTMs with at least six channels for each motor are required for sensing the mechanical quantities rotor speed and the rotor position of each motor The actual position is obtained by decoding the signals from an incremental sensor and the rotor speed is calculated as the position change in time Dual Motor Control for PMSM with the Kinetis K70 Rev 0 2011 Freescale Semiconductor Inc 3 Dual motor controli K70 Peripheral interconnection Power source 1 Position User interface Position Power source 2 Figure 2 Topology of dual motor control Dual Motor Control for PMSM with the Kinetis K70 Rev 0 2011 4 Freescale Semiconductor Inc Dual motor control K70 Table 1 Kinetis K70 peripherals overview for dual PMSM FOC Submodule and Used in the Purpose channels available application Timers 4 channels 1 channel Time base for speed calculation and speed regulation FTM FTM1 8 channels 6 channels Generation of 6 PWM channels for the first motor FTM2 2 channels 2 channels FTM3 2 channels 2 channels Quadrature encoder s
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