FOC using Optical Encoder for PMSM: MCLV-48V-300W Development Board and dsPI33AK128MC106 Motor Control DIM

1. INTRODUCTION

This document describes driving a Permanent Magnet Synchronous Motor (PMSM) using Field Oriented Control (FOC) based on optical encoder feedback on the hardware platform EV18H47A "MCLV-48V-300W Development Board" and EV68M17A "dsPIC33AK128MC106 Motor Control Dual In-line Module (DIM)".

The Quadrature Encoder Interface peripheral of the dsPIC DSC is configured to obtain the position and speed information from the opitical encoder feedback of the motor.

2. SUGGESTED DEMONSTRATION REQUIREMENTS

2.1 Motor Control Application Firmware Required for the Demonstration

To clone or download this application firmware on GitHub,

• Navigate to the main page of this repository and
• On the tab <> Code, above the list of files in the right-hand corner, click Code, then from the menu, click Download ZIP or copy the repository URL to clone.

Note:
In this document, hereinafter this firmware package is referred as firmware.

2.2 Software Tools Used for Testing the firmware

• MPLAB® X IDE v6.20
• Device Family Pack (DFP): dsPIC33AK-MC_DFP v1.0.33
• Curiosity/Starter Kits Tool Pack : PKOB4_TP v1.14.1168
• MPLAB® XC-DSC Compiler v3.10
• MPLAB® X IDE Plugin: X2C-Scope v1.6.6

Note:
The software used for testing the firmware prior to release is listed above. It is recommended to use these or later versions of the tool for building the firmware. All previous versions of Device Family Packs (DFP) and Tool Packs can be downloaded from Microchip Packs Repository.

2.3 Hardware Tools Required for the Demonstration

• MCLV-48V-300W Development Board (EV18H47A)
• dsPIC33AK128MC106 Motor Control Dual In-line Module (EV68M17A)
• 24V Power Supply (AC002013)
• 24V 3-Phase Brushless DC Motor - Hurst DMA0204024B101 (AC300022)

Note:
All items listed under the section Hardware Tools Required for the Demonstration are available at microchip DIRECT

• Hurst DMA0204024B101(AC300022) is referred as Hurst300 or Long Hurst in the firmware

3. HARDWARE SETUP

This section describes the hardware setup required for the demonstration.

Note:
In this document, hereinafter the MCLV-48V-300W Development Board is referred as development board.

1. Motor currents are amplified on the MCLV-48V-300W development board; it can also be amplified by the amplifiers internal to the dsPIC33AK128MC106 on the DIM. The firmware and DIM are configured to sample and convert internal amplifier outputs ('internal op-amp configuration') by default to measure the motor currents needed to implement FOC. Table-1 summarizes the resistors to be populated and removed to convert the DIM from ‘internal op-amp configuration’ to ‘external op-amp configuration’ or vice versa.

   

2. Insert the dsPIC33AK128MC106 Motor Control DIM into the DIM Interface connector J8 on the development board. Make sure the DIM is placed correctly and oriented before going ahead.

   

3. Connect the 3-phase wires from the motor to PHC, PHB, and PHA of the connector J4, provided on the development board.

   Development Board	Hurst300 Motor
   	Winding Terminals (Color as per image below)	Power Connector (Molex 39-01-2040)
   PHC	Red	1
   PHB	Black	2
   PHA	White	3

   

4. Interface the encoder of the motor to connector J7, provided on the Development Board as mentioned in the below table.

   Development Board	Hurst300 Motor
   	Encoder Connection-wire color	Encoder Connector (FCI Connect #69168-108)
   +5V	Red	1
   DGND	Black	8
   Q_A	White	5
   Q_B	Blue	6

   
   

   

   
   

5. Plug the 24V power supply to connector J1 on the development board. Alternatively, the development board can also be powered through connector J3.

   

6. The board has an onboard programmer PICkit™ On Board (PKoBv4) , which can be used for programming or debugging the microcontroller or dsPIC DSC on the DIM. To use the onboard programmer, connect a micro-USB cable between the Host PC and connector J16 on the development board.

   

7. Alternatively, connect the Microchip programmer/debugger MPLAB® PICkit™ 4 In-Circuit Debugger(PG164140) between the Host PC used for programming the device and the ICSP header J9 on the development board (as shown). Ensure that PICkit 4 is oriented correctly before proceeding.

   

4. SOFTWARE SETUP AND RUN

4.1 Setup: MPLAB X IDE and MPLAB XC-DSC Compiler

Install MPLAB X IDE and MPLAB XC-DSC Compiler versions that support the device dsPIC33AK128MC106 and PKoBv4. The MPLAB X IDE, MPLAB XC-DSC Compiler, and X2C-Scope plug-in used for testing the firmware are mentioned in the Motor Control Application Firmware Required for the Demonstration section.

To get help on

• MPLAB X IDE installation, refer link
• MPLAB XC-DSC Compiler installation steps, refer link

If MPLAB IDE v8 or earlier is already installed on your computer, then run the MPLAB driver switcher (Installed when MPLAB®X IDE is installed) to switch from MPLAB IDE v8 drivers to MPLAB X IDE drivers. If you have Windows 8 or 10, you must run the MPLAB driver switcher in Administrator Mode. To run the Device Driver Switcher GUI application as administrator, right-click on the executable (or desktop icon) and select Run as Administrator. For more details, refer to the MPLAB X IDE help topic “Before You Begin: Install the USB Device Drivers (For Hardware Tools): USB Driver Installation for Windows Operating Systems.”

4.2 Setup: X2C-SCOPE

X2C-Scope is a MPLAB X IDE plugin that allows developers to interact with an application while it runs. X2C-Scope enables you to read, write, and plot global variables (for motor control) in real-time. It communicates with the target using the UART. To use X2C-Scope, the plugin must be installed. To set up and use X2C-Scope, refer to the instructions provided on the web page.

5. BASIC DEMONSTRATION

5.1 Firmware Description

The firmware version needed for the demonstration is mentioned in the section Motor Control Application Firmware Required for the Demonstration section. This firmware is implemented to work on Microchip’s Digital signal controller (dsPIC® DSC) dsPIC33AK128MC106. For more information, see the dsPIC33AK128MC106 Family datasheet (DS70005539).

The Motor Control Demo application uses a push button to start or stop the motor and a potentiometer to vary the speed of the motor. This Motor Control Demo Application configures and uses peripherals like PWM, ADC, UART, etc. For more details, refer to Microchip Application note AN1292, “Sensorless Field Oriented Control (FOC) for a Permanent Magnet Synchronous Motor (PMSM) Using a PLL Estimator and Field Weakening (FW)” available on the Microchip website.

Note:
The project may not build correctly in Windows OS if the Maximum path length of any source file in the project is more than 260 characters. In case the absolute path exceeds or nears the maximum length, do any (or both) of the following:

• Shorten the directory name containing the firmware used in this demonstration. If you renamed the directory, consider the new name while reading the instructions provided in the upcoming sections of the document.
• Place firmware in a location such that the total path length of each file included in the projects does not exceed the Maximum Path length specified.
  Refer to MPLAB X IDE help topic “Path, File, and Folder Name Restrictions” for details.

5.2 Basic Demonstration

Follow the below instructions, step by step, to set up and run the motor control demo application:

1. Start MPLAB X IDE and open the project pmsm.X (File > Open Project) with device selection dsPIC33AK128MC106.

   

2. Set the project pmsm.X as the main project by right-clicking on the project name and selecting Set as Main Project as shown. The project pmsm.X will then appear in bold.

   

3. Open userparms.h (pmsm.X > Header Files) in the project pmsm.X.

   • Ensure that the macros TORQUE_MODE, and SINGLE_SHUNT is not defined in the header file userparms.h.

     

   • When internal amplifiers are used for current amplification (referred to as internal op-amp configuration), define the macro INTERNAL_OPAMP_CONFIG in userparms.h.

     

   • Otherwise, if external amplifiers are used for current amplification (referred to as external op-amp configuration), undefine the macro INTERNAL_OPAMP_CONFIG in the header file userparms.h.

     

   • In order to enter the extended speed range (END_SPEED_RPM to MAXIMUM_SPEED_RPM), define the macroFLUX_WEAKENING_ENABLE .

     

Note:
The motor phase currents can be reconstructed from the DC Bus current by appropriately sampling it during the PWM switching period, called as single-shunt reconstruction algorithm. The firmware can be configured to demonstrate the single shunt reconstruction algorithm by defining the macro SINGLE_SHUNT in the header file userparms.h For additional information, refer to Microchip application note AN1299, “Single-Shunt Three-Phase Current Reconstruction Algorithm for Sensorless FOC of a PMSM.” By default, the firmware uses phase currents measured across the phase shunt resistors on two of the half-bridges of the three-phase inverter (‘dual shunt configuration’) to implement FOC.

4. Right-click on the project pmsm.X and select Properties to open its Project Properties Dialog. Click the Conf:[default] category to reveal the general project configuration information. The development tools used for testing the firmware are listed in section 2.2 Software Tools Used for Testing the firmware.

   In the Conf:[default] category window:

   • Ensure the selected Device is dsPIC33AK128MC106.
   • Select the Connected Hardware Tool to be used for programming and debugging.
   • Select the specific Device Family Pack (DFP) from the available list of Packs. In this case, dsPIC33AK-MC_DFP 1.0.33 is selected.
   • Select the specific Compiler Toolchain from the available list of XC-DSC compilers. In this case, XC-DSC(v3.10) is selected.
   • After selecting Hardware Tool and Compiler Toolchain, Device Pack, click the button Apply

   Please ensure that the selected MPLAB® XC-DSC Compiler and Device Pack support the device configured in the firmware

   

5. Ensure that the checkbox Load symbols when programming or building for production (slows process) is checked under the Loading category of the Project Properties window.

   

   Also, go to Tools > Options , and

   

   Open the Embedded > Generic Settings tab and ensure that the ELF debug session symbol load methodology (MIPS/ARM) is selected as Pre-procesed (Legacy) from the drop down.

   

6. To build the project (in this case, pmsm.X) and program the device dsPIC33AK128MC106, click Make and Program Device Main project on the toolbar

   

7. If the device is successfully programmed, LED1 (LD2) will be blinking, indicating that the dsPIC® DSC is enabled.

   

8. Run or stop the motor by pressing the push button SW1. The motor should start spinning smoothly in one direction in the nominal speed range. Ensure that the motor is spinning smoothly without any vibration. The LED LED2(LD3) is turned ON to show the button is pressed to start the motor.

   

9. The motor speed can be varied using the potentiometer (POT1).

   

10. Press the push button SW2 to change the motor direction.

    

11. Press the push button SW1 to stop the motor.

Note:
The macros END_SPEED_RPM, NOMINAL_SPEED_RPM, and MAXIMUM_SPEED_RPM are specified in the header file userparms.h included in the project pmsm.X. The macros NOMINAL_SPEED_RPM and MAXIMUM_SPEED_RPM are defined as per the Motor manufacturer’s specifications. Exceeding manufacture specifications may damage the motor or the board or both.

5.3 Data visualization through X2C-Scope Plug-in of MPLAB X

X2C-Scope is a third-party plug-in in MPLAB X, which helps in real-time diagnostics. The application firmware comes with the initialization needed to interface the controller with the host PC to enable data visualization through the X2C-Scope plug-in. Ensure the X2C-Scope plug-in is installed. For more information on how to set up a plug-in, refer to either the Microchip Developer Help page or the web page.

1. To establish serial communication with the host PC, connect a micro-USB cable between the host PC and connector J16 on the development board. This interface is also used for programming.

2. Ensure the application is configured and running as described under section 5.2 Basic Demonstration by following steps 1 through 11.

3. Open the X2C-Scope window by selecting Tools>Embedded>X2CScope.

   

4. In the X2C-Scope Configuration window, open the Connection Setup tab and click Select Project. This opens the drop-down menu Select Project with a list of opened projects. Select the specific project pmsm from the list of projects and click OK.

   

5. To configure and establish the serial communication for X2C-Scope, open the X2CScope Configuration window, click on the Connection Setup tab and:

   • Set Baudrate as 115200, which is configured in the application firmware.
   • Click on the Refresh button to refresh and update the list of the available Serial COM ports connected to the Host PC.
   • Select the specific Serial port detected when interfaced with the development board. The Serial port depends on the system settings

   

6. Once the Serial port is detected, click on Disconnected and turn to Connected, to establish serial communication between the Host PC and the board.

   

7. Open the Project Setup tab in the X2CScope Configuration window and,

   • Set Scope Sampletime as the interval at which X2CScopeUpdate() is called. In this application, it is every 50µs.
   • Then, click Set Values to save the configuration.

   

8. Click on Open Scope View (in the Data Views tab of the X2CScope Configuration Window); this opens Scope Window.

   

9. In the Scope Window, select the variables that must be watched. To do this, click on the Source against each channel, and a window Select Variables opens on the screen. From the available list, the required variable can be chosen. Ensure checkboxes Enable and Visible are checked for the variables to be plotted. To view data plots continuously, uncheck Single-shot. When Single-shot is checked, it captures the data once and stops. The Sample time factor value multiplied by Sample time decides the time difference between any two consecutive data points on the plot.

   

10. Click on SAMPLE, then the X2C-Scope window plots variables in real-time, which updates automatically.

    

11. Click on ABORT to stop.

    

6. REFERENCES:

For additional information, refer following documents or links.

1. AN1292 Application Note “Sensorless Field Oriented Control (FOC) for a Permanent Magnet Synchronous Motor (PMSM) Using a PLL Estimator and Field Weakening (FW)”
2. AN1299 Application Note “Single-Shunt Three-Phase Current Reconstruction Algorithm for Sensorless FOC of a PMSM”
3. MCLV-48V-300W Development Board User’s Guide (DS50003297)
4. dsPIC33AK128MC106 Motor Control Dual In-Line Module (DIM) Information Sheet (DS70005527)
5. dsPIC33AK128MC106 Family datasheet (DS70005539)
6. MPLAB® X IDE User’s Guide (DS50002027) or MPLAB® X IDE help
7. MPLAB® X IDE installation
8. MPLAB® XC-DSC Compiler installation
9. Installation and setup of X2Cscope plugin for MPLAB X
10. Microchip Packs Repository
11. Programming and Debugging the dsPIC33A on MPLAB X IDE v6.20 and IPE v6.20