NXP Application Code Hub

Implementation of Motor Control Algorithms to MCIMX93-EVK

Implementation of motor control algorithms using the MCIMX93-EVK development kit. It includes hardware configuration details, setup instructions, and an overview of the software implementation process.

Boards: MCIMX93-EVK

Categories: Motor Control

Peripherals: PWM, GPIO, ADC

Toolchains: IAR

Table of Contents

1. Software
2. Hardware
3. Setup
4. Application start-up using IAR
5. Results
6. FAQs
7. Support
8. Known Issues
9. Release Notes

1. Software

• Download and install IAR Embedded Workbench for ARM v 9.50.1 or above.
• Download and install the latest version of FreeMASTER (3.2.2.2) or above.
• Download and install the latest version of CM33F_RTCESL_4.7.1 or above.
• J-Link FW with the latest available version.
• Download patch for J-Link debug probe to support i.MX93 from here and follow the instructions in README.txt document in downloaded folder.

2. Hardware

• MCIMX93-EVK
• FRDM-MC-LVPMSM.
• AdaptBoard_MCXN94LC_MC
  • schematic included in the Base Board.zip file.
• Custom base board
  • see the board design in the Base Board.zip file.
• Motor MCG IB 23810
• J-Link debug probe
• Personal Computer

3. Setup

3.1 Power stage

The power stage consists of custom baseboard, AdaptBoard, and Freedom LVPMSM board.

The custom baseboard was essential to adapt the LVPMSM pinout to the MCIMX93-EVK GPIO header (J1001) and to step down the ADC voltage. Additionally, DC-Bus overcurrent protection is managed through this board.

3.1.1 Custom Base Board

This board is utilized for connection of MCIMX93-EVK and Freedom LVPMSM. Schematic and board visualization are shown below.

The boards are interconnected via a cable from connector J9 on the Base Board to GPIO Header J1001 on the MCIMX93-EVK. This header contains PWM outputs, Encoder signals (Ch A, Ch B), 3V3 supply voltage for the Freedom LVPMSM, and GND connection.

For the ADC connection, header J10 is utilized, which is linked to connector J1003 on the MCIMX93-EVK through soldered wires. The ADC voltage from the Freedom LVPMSM board is stepped down to 1V8 using voltage dividers before being connected to connector J10.

Since only 4 ADC channels are available on the MCIMX93-EVK, the measured DC-Bus current is managed by voltage comparator U3. It functions as a fault protection for Over DC-Bus current. When the voltage exceeds the threshold of 6.65 A, GPIO2 pin 0 is set to logic zero, triggering an interrupt and switching the PWMs to the off state. The output is connected to pin 27 on connector J9.

A 3V3 supply is required for the ICs on the Freedom LVPMSM board. This voltage is provided by the MCIMX93-EVK.

3.1.2 Adapt Board

The board's connector JC1 is linked to the baseboard connectors J5 and J7, while connector JC2 is connected to J6 and J8. It is important to ensure that the first pin of the JC2 connector aligns with the first pin of the J8 connector.

^{Note: The Adapt Board was introduced due to limitations of available hardware. This board is not necessary for future use of motor control algorithms with i.MX93, if the Custom Base Board's pins will fit the Freedom LVPMSM board.}

3.1.3 Freedom LVPMSM board

The LVPMSM board should be connected directly to AdaptBoard.

The motor phases shall be connected to the connector J7, according to schematic of the board.

The encoder shall be connected to connector J8, according to schematic of the board.

3.2 MCIMX93-EVK configuration

Connect PC to J1401 on MCIMX93-EVK using a USB-C to USB-A cable to enable serial communication. This will be used for real-time control of the application using FreeMASTER.

Connect the J-Link debug probe to the JTAG connector (J1405) on the board.

The boot switches should be set to boot from FlexSPI Serial NOR. Set SW1301 to 1101 [4-1].

Connect the USB-C Power cable to connector J301.

Connect the ADC inputs from custom base board connector J10 (pins 2, 4, 6, 8 ) to connector’s J1003 pins 1, 3, 5, 7, which correspond to SAR_ADC0’s channels 0, 1, 2, 3.

Connect the GPIO header J1001 to the header J9 on the custom base board.

3.3 Software initialization

Peripheral drivers for the Timer, PWM, ADC, and GPIO selector (onboard chip) are defined in file Peripherals.h, which can be found in the “source\peripherals” group. FreeMASTER drivers are in the group Freemaster.

1. It is needed to initialize the GPIO Extender on MCIMX-EVK. These ICs act like switches for GPIO outputs.

   • GPIO_SEL_Init() function shall be used.

   • This function utilizes I2C for communication with GPIO Extender.

   • It is mandatory to initialize the GPIO Extender, because PWM signals pass through it.

2. Clocks and pins shall be initialized.

   • Used GPIO pins are summarized in table below.
   • Default clock for TPM4, TPM5 and TPM6 is 24 MHz.

   GPIO pin	ALT	I/O	Function
   GPIO05	TPM4 Ch0	Output	PWM AT
   GPIO21	TPM4 Ch1	Output	PWM AB
   GPIO13	TPM4 Ch2	Output	PWM BT
   GPIO25	TPM4 Ch3	Output	PWM BB
   GPIO19	TPM6 Ch2	Output	PWM CT
   GPIO27	TPM6 Ch3	Output	PWM CB
   GPIO06	TPM5 Ch0	Input	Encoder Ch A
   GPIO22	TPM5 Ch1	Input	Encoder Ch B
   GPIO04	GPIO04	Output	LED Blue
   GPIO12	GPIO12	Output	LED Green
   GPIO00	GPIO00	Input	Over DC Bus current protection

3. Fault handling is initialized with functions PWM_GPIO_INIT() and GPIO_Fault_Handler().

   • PWM_GPIO_INIT() initializes all GPIO outputs used for PWM to logic 0 and sets the GPIOs for output.
   • GPIO_Fault_Handler() enables IRQ for pin 0 of GPIO in case of over DC Bus current.

4. PWM is initialized using function InitPWM(TPM_Type *base1, TPM_Type*base2). The PWM is initialized for TPM4 and TPM6 in up-down counting mode.

   • PWM period is set by macro PWM_PERIOD in file Peripherals.h.
   • Deadtime used for PWM generation is set with macro DEAD_TIME.
   • Duty cycle is limited due to timer hardware limitation. This is handled with macro MAX_DUTY.

5. EncoderInit(TPM_Type *TPM) initializes the TPM5 Ch0 and Ch1 for encoder input.

6. InitADC() is used for ADC initialization.

   • Signals are measured sequentially.
   • Channels 0 – 3 are used for Motor Control application as shown in table:

   ADC Channel	Measured signal
   SAR_ADC Ch 0	Phase A current
   SAR_ADC Ch 1	Phase B current
   SAR_ADC Ch 2	Phase C current
   SAR_ADC Ch 3	DC Bus voltage

7. TPM channels will be updated only if there is enough time left for the update. Minimal time needed for Update3PWM(frac16_t phaseA, frac16_t phaseB, frac16_t phaseC) execution is 4.25 $\mu s$. If the algorithm is taking longer to compute the TPM registers won't be updated.

4. Application start-up using IAR

Project in IAR is using RTCESL library with version 4.7.1 (CM33F_RTCESL_4.7.1_IAR). For correct functionality of the app the library should be saved in C:\nxp\RTCESL.

Note: To support i.MX93, the patch for IAR and Segger J-Link must be installed. To download, navigate to https://www.nxp.com/webapp/Download?colCode=SDK_MX93_3RDPARTY_PATCH&appType=license.

1. Create new workspace in IAR EW (v. 9.50.1)

2. Project -> Import project files

   • Browse for project location (...\MCIMX93352_PMSM\).
   • Open file "iMX93_PMSM_Control.ewp”.

3. In group “source” open file “main.c”.

4. Build project using Project –> Make (F7).

   

5. Connect the cables and connectors according to Hardware configuration.

6. Turn on the power supply for MCIMX93-EVK using SW301.

7. Download and debug the project:

   

8. In group source\freemaster you can find FreeMASTER application, double click it to open FreeMASTER.

4.1 FreeMASTER Application

In FreeMASTER you need to find right COM port. When you connect the board to PC there will be 4 new ports. For Serial Communication with FreeMASTER you need to choose the last port. In this case COM7:

Most of the application control can be done from “foc” subblock located on the left side of the application.

Variables needed for motor control are shown in the “Variable Watch” window located at the bottom of the screen:

4.1.1 Running the application

The application can be turned on/off by writing 1 or 0 respectively into the variable cntrState.switchAppOnOff. Control mode can be switched between scalar control, voltage control, current (torque) control, and speed control. The switchSensor variable is used to switch between various sensor less methods. You can watch the variables live using oscilloscopes or recorders located on the left side of the screen. The current shall not exceed 2 A.

4.1.2 Sensor less algorithm enablement

To enable calculation of Back-EMF observer navigate to Back-EMF Obs subblock. It is needed to change variable BemfObs_ON_OFF to 1. This will enable the observer. To change the observer dynamics, change the value of variable set_BemfObs_SL to 1. You can now change the value of f_BemfObs E_BemfObs f_BemfObs_ATO E_BemfObs_ATO, and f_BemfObs_LPF, which will result in change of the observer's dynamics. To use the speed from the observer as a feedback in the speed control, change variable switchSensor to 1 or Bemf_SL.

4.1.3 Scalar and speed control

In scalar and speed control mode, it is possible to set the required speed for the motor using the FOC_n_Mech_Req variable. After changing the variable value the motor will start to spin at the required speed. You can check this value in the oscilloscope/recorder “foc->n Mech – i_DQ”. To use the speed control a sensor (encoder) or sensor less algorithm is needed.

4.1.4 Voltage control

To change the voltage in the d or q axis you need to change the variable foc.uDQReq.fltD or foc.uDQReq.fltQ respectively.

4.1.5 Current (torque) control

To change the current in the d or q axis you need to change the variable foc.i_DQ_Req.fltD or foc.i_DQ_Req.fltQ respectively. This will allow you to control the flux and torque-producing components of the motor. In case you want to run the motor, you need to change the required value of current in the q-axis (torque-producing axis). The motor will spin at a speed that corresponds to the available voltage value in the axis.

4.1.6 Algorithm tuning

Current and speed loop dynamics can be tuned using the variables f_i_PI, f_w_PI, E_w_PI. Higher values of frequency f make the regulation faster. To enable controllers' tuning you need to change the value of variables set_i_PI, set_w_PI to 1, respectively.

4.2 Fault State

The application works in various states, when the application reaches a state fault, it is necessary to remove the cause of the fault, otherwise, you won’t be able to turn on the application. Faults can be checked in the “faults” subblock. To clear the fault, write 1 to the variable cntrState.switchFaultClear. This will send the application to the “Init” state. In this state, all variables are initialized to default values.

5. Results

It is now possible to control PMSM using i.MX93. The source code can be updated with additional control strategies.

6. FAQs

No FAQs have been identified for this project.

7. Support

• Reference manual i.MX93

8. Known issues

• The ADC interrupt is not working after downloading the source code for second time. It is needed to reset the EVK, either by turning the board off/on or using the Reset button.
• Individual errors are not visible in FreeMASTER application.

Project Metadata

Questions regarding the content/correctness of this example can be entered as Issues within this GitHub repository.

Warning: For more general technical questions regarding NXP Microcontrollers and the difference in expected functionality, enter your questions on the NXP Community Forum

9. Release Notes

Version	Description / Update	Date
1.0	Initial release on Application Code Hub	June 24th 2024

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