Optical Encoder based FOC for PMSM: dsPIC33CK Low Voltage Motor Control Board

1. INTRODUCTION

This demonstration describes a method of driving Permanent Magnet Synchronous Motor (PMSM) using optical encoder based Field Oriented Control (FOC) on the hardware platform dsPIC33CK Low Voltage Motor Control Board (LVMC).

The Quadrature Encoder Interface (QEI) perpheral of the dsPIC DSC can be 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
• DFP: dsPIC33CK-MP_DFP v1.13.366
• MPLAB® XC-DSC Compiler v3.00
• 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 the version listed above or later versions for building the firmware.

2.3 Hardware Tools Required for the Demonstration

• dsPIC33CK Low Voltage Motor Control Board (DM330031)
• 24V Power Supply (AC002013)
• 24V 3-Phase Brushless DC Motor With Encoder (AC300022)

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

3. HARDWARE SETUP

This section describes hardware setup required for the demonstration.

1. Connect the three phase wires from the motor to PHA, PHB & PHC terminals of connector J14, provided on the Development Board as mentioned in the below table.

LVMC 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

2. Connect the encoder from the motor to QEA and QEB terminals of connector J8, provided on the Development Board as mentioned in the below table.

LVMC Board	Hurst300 Motor
	Hall Terminals(Color as per image above)	Encoder Connector (FCI Connect #69168-108)
5V	Red	1
GND	Black	8
QEA	White	5
QEB	Blue	6

3. Plug the 24V power supply to connector J1 on the dsPIC33CK Low Voltage Motor Control Board.Alternatively, the Board can also be powered through connector J2.

   
   

   

4. The board has an onboard programmer PICkit™ On Board (PKoBv4) , which can be used for programming or debugging the microcontroller or dsPIC DSC. To use the onboard programmer, connect a micro-USB cable between the Host PC and connector J13 on the dsPIC33CK Low Voltage Motor Control Board.

   

   
   

5. Alternatively, connect the Microchip programmer/debugger MPLAB PICkit 4 In-Circuit Debugger between the Host PC used for programming the device and the ICSP header J10 on the dsPIC33CK Low Voltage Motor Control Board (as shown). Ensure that PICkit 4 is connected in correct orientation.

   

   
   

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 dsPIC33CK256MP508 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 an 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 16-bit Digital signal controller (dsPIC® DSC) dsPIC33CK256MP508. For more information, see the dsPIC33CK256MP508 Family datasheet (DS70005349).

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, QEI, etc.

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 dsPIC33CK256MP508.

   

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.

     

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

     

   Note:
   The motor phase currents can be reconstructed from the DC Bus current by appropriately sampling it during the PWM switching period, called a 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 dsPIC33CK256MP508.
   • 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, dsPIC33CK-MP_DFP 1.13.366 is selected.
   • Select the specific Compiler Toolchain from the available list of XC-DSC compilers. In this case, XC-DSC(v3.00) 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

   

   ensure in the Embedded > Generic Settings tab 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_hall.X) and program the device dsPIC33CK256MP508, click Make and Program Device Main project on the toolbar

   

7. If the device is successfully programmed, LD11 (LED2) will be turned ON, 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.

   

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 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 J13 on the dsPIC33CK Low Voltage Motor Control Board. This interface is also used for programming. Alternatively connect a micro-USB cable from your computer to the J6 connector of the dsPIC33CK Low Voltage Motor Control Board.

   

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 LVMC 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.

    

 

REFERENCES:

For additional information, refer following documents or links.

1. MATLAB-Simulink model for Optical Encoder Based FOC using LVMC.
2. dsPIC33CK Low-Voltage Motor Control Development Board (DM330031) User's Guide
3. dsPIC33CK256MP508 Family datasheet (DS70005349).
4. Family Reference manuals (FRM) of dsPIC33CK256MP508 family
5. MPLAB® X IDE User’s Guide (DS50002027) or MPLAB® X IDE help
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