Motor Control Examples

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⚠️ Third-Party Educational Content

The motor control examples and algorithms presented in this guide are provided by the ctrl-elec project, an educational initiative from INSA Lyon (France).

Attribution:

Project: ctrl-elec - Real-time Control & Embedded Systems Education
Institution: Institut National des Sciences Appliquées de Lyon (INSA Lyon)
Website:[https://www.ctrl-elec.fr/]
GitHub Repository:[https://github.com/rdelpoux/ctrl-elec]
RCP Platform:[http://rcp.ctrl-elec.fr/]

License: Educational use - Please refer to the ctrl-elec website for specific licensing terms.

This content is included in the MPLAB Device Blocks for Simulink documentation to demonstrate real-world motor control applications. Microchip Technology and the MPLAB Device Blocks toolbox are separate from the ctrl-elec project.

Introduction

This guide demonstrates how to use the MPLAB Device Blocks for Simulink toolbox for motor control applications, using examples and educational materials from the ctrl-elec project (INSA Lyon).

The examples showcase:

Field-Oriented Control (FOC) for Permanent Magnet Synchronous Motors (PMSM)
Sensorless control using position and speed observers
Field weakening for extended speed range operation
Real-time parameter tuning using External Mode
Hardware-in-the-loop testing with dsPIC33 and PIC32 devices

Prerequisites:

        Understanding of motor control theory (vector control, Park/Clarke transforms)
        Familiarity with Simulink and Model-Based Design
        Microchip development hardware (e.g., MCLV-2, dsPICDEM MCLV)

Example 1: Field-Oriented Control (FOC) for PMSM

Overview

Field-Oriented Control (FOC) provides precise control of PMSM torque and speed by independently controlling flux and torque-producing currents in the rotating reference frame (d-q frame).

Control Algorithm Components

Component	Function	MPLAB Blocks Used
Clarke Transform	Converts 3-phase currents (a,b,c) to stationary frame (α,β)	Math blocks (Simulink standard)
Park Transform	Converts stationary frame (α,β) to rotating frame (d,q)	Math blocks with rotor position input
PI Controllers	Regulate d-axis and q-axis currents independently	Discrete PID blocks with anti-windup
Inverse Park	Converts voltage commands (Vd, Vq) to stationary frame	Math blocks with angle input
Space Vector Modulation	Generates 3-phase PWM duty cycles	MCHP_PWM_HS or MCHP_PWM_HS_FEP
Current Sensing	Measures motor phase currents	MCHP_ADC with PWM-synchronized sampling
Position/Speed Estimation	Encoder or sensorless observer	MCHP_QEI (encoder) or observer algorithm

Implementation Steps

Hardware Configuration
Configure PWM outputs using MCHP_PWM_HS_FEP block
Set PWM frequency (typically 10-20 kHz)
Enable complementary mode with dead-time insertion
Configure center-aligned PWM for reduced harmonics
ADC Setup
Use MCHP_ADC block for current sensing
Trigger ADC from PWM for synchronous sampling
Sample at PWM valley or peak for accurate measurements
Enable ADC interrupt for time-critical control loop
Control Loop Structure
Outer loop: Speed controller (lower rate, e.g., 1 kHz)
Inner loop: Current controller (higher rate, e.g., 10 kHz)
Use multi-rate model with appropriate task priorities
Parameter Tuning
Enable External Mode for real-time tuning
Use picgui for lightweight data visualization
Adjust PI gains using Ziegler-Nichols or model-based methods

Key Peripheral Blocks

Block Name	Configuration	Purpose in FOC
MCHP_Master	Select target device, enable multi-tasking	System configuration and scheduler
MCHP_PWM_HS_FEP	3-phase complementary, center-aligned, 10 kHz	Drive motor inverter (6 IGBTs/MOSFETs)
MCHP_ADC	2 channels (phase currents), PWM-triggered	Measure Ia, Ib (Ic calculated)
MCHP_QEI	Quadrature encoder interface, 1024 PPR	Rotor position and speed feedback
MCHP_UART_Config	115200 baud, XCP protocol	External Mode communication
MCHP_Interrupt	Timer or ADC interrupt, highest priority	Trigger fast current control loop

Safety Considerations:

        Implement overcurrent protection using ADC limits and emergency shutdown
        Add dead-time compensation to prevent shoot-through
        Test control algorithm in simulation before hardware deployment
        Use current limiting during startup and parameter tuning
        Monitor MCU load to prevent scheduler overruns

Example 2: Sensorless Control with Sliding Mode Observer

Overview

Sensorless control eliminates the need for mechanical position sensors by estimating rotor position and speed from electrical measurements (voltages and currents). This example uses a Sliding Mode Observer (SMO) for robust position estimation.

Observer Algorithm Components

Component	Function	Implementation Notes
Current Observer	Estimates stator currents using motor model	Uses measured voltages and motor parameters (Rs, Ls)
Back-EMF Estimation	Extracts back-EMF from current error	Sliding mode function with adaptive gain
Position Calculation	Computes rotor angle from back-EMF (α,β)	Arctangent function with phase compensation
Speed Estimation	Differentiates position or uses PLL	Low-pass filter to reduce noise
Startup Strategy	Open-loop alignment then transition to sensorless	Forced angle ramp until sufficient back-EMF

MPLAB Blocks Configuration

Block Name	Configuration	Purpose in Sensorless Control
MCHP_ADC	4 channels: Ia, Ib, Vdc, temperature	Measure currents and DC bus voltage
MCHP_PWM_HS_FEP	Same as FOC example	Motor drive PWM generation
Observer Subsystem	Fixed-point or floating-point math	Sliding mode observer implementation
MCHP_Interrupt	ADC interrupt at PWM frequency	Execute observer at high rate (10-20 kHz)

Key Tuning Parameters

Observer Gain (k_smo): Trade-off between convergence speed and noise sensitivity
Low-Pass Filter Cutoff: Filter back-EMF signals without excessive phase delay
Transition Speed: Minimum speed for sensorless operation (typically 5-10% rated speed)
Startup Ramp Rate: Balance between fast startup and smooth transition

Advantages of Sensorless Control:

        Reduced hardware cost (no encoder)
        Higher reliability (no mechanical sensor to fail)
        Simplified wiring and installation
        Suitable for harsh environments
    
    Limitations:
    
        Poor performance at zero/low speed
        Requires accurate motor parameters
        Sensitive to parameter variations (temperature, saturation)
        More complex tuning process

Example 3: Field Weakening Control

Overview

Field weakening extends the speed range of PMSM beyond the base speed by injecting negative d-axis current. This reduces the flux linkage, allowing higher speeds while maintaining voltage within DC bus limits.

Field Weakening Strategy

Operating Region	Control Strategy	Id Command	Iq Command
Constant Torque (ω < ωbase)	Maximum torque per ampere (MTPA)	0 A (or slightly negative), Limited by max current
Field Weakening (ωbase < ω < ωmax)	Voltage-limited operation	Negative (increases with speed)	Adjusted to maintain voltage limit
Constant Power (ω ≈ ωmax)	Maximum speed operation	Maximum negative Id	Reduced for voltage constraint

Implementation with MPLAB Blocks

Voltage Limit Calculation
Measure DC bus voltage using MCHP_ADC
Calculate maximum voltage: Vmax = Vdc / √3 (for SVPWM)
Account for voltage drops and modulation overhead
Field Weakening Controller
Input: Speed feedback, voltage magnitude, current limits
Output: Id_ref (d-axis current command)
Algorithm: PI controller on voltage error or lookup table
Current Limiting
Enforce circular current limit: √(Id² + Iq²) ≤ Imax
Priority given to Id (flux control) at high speeds
Reduce Iq if total current exceeds limit

Tuning Guidelines

Parameter	Typical Range	Effect
Base Speed (ωbase)	Rated speed or design speed	Transition point to field weakening
Max Id Current	50-80% of rated current	Maximum field weakening capability
Voltage Margin	5-10% below Vmax	Safety buffer for control headroom
FW Controller Gain	Tuned for stability	Response speed vs. oscillations

Field Weakening Considerations:

        Increased copper losses due to higher total current
        Reduced efficiency at high speeds
        Risk of demagnetization with excessive negative Id
        Requires precise voltage and current limiting
        Test carefully with thermal monitoring

Development Workflow with MPLAB Blocks

Step 1: Model Development

Start from MCHP template for target device (e.g., dsPIC33CK Curiosity Board)
Add peripheral blocks: PWM, ADC, QEI, UART
Implement control algorithm using Simulink blocks
Configure multi-rate model: Fast loop (current) + Slow loop (speed)

Step 2: Simulation and Validation

Test algorithm with motor model in Simulink
Verify control stability and transient response
Check for numerical issues (saturation, overflow)
Optimize fixed-point data types for embedded implementation

Step 3: Code Generation and Deployment

Configure Embedded Coder settings in MCHP Master block
Generate C code and compile for target device
Program device using MPLAB X IPE or ICD
Use picgui or MPLAB Data Visualizer for initial debugging

Step 4: Real-Time Tuning

Enable External Mode in MCHP Master block
Connect via UART or USB to development PC
Adjust controller gains and parameters in real-time
Log data for post-processing and analysis

Step 5: Performance Optimization

Run PIL (Processor-in-the-Loop) test for execution time analysis
Optimize code with dsPIC assembly replacements (if needed)
Monitor CPU load using MCHP_MCULoad block
Verify scheduler timing with MCHP_TasksState block

Accessing ctrl-elec Resources

Educational Materials

Website:[https://www.ctrl-elec.fr/]
Comprehensive tutorials on motor control theory
Detailed explanations of FOC, sensorless control, and field weakening
Step-by-step lab exercises with MATLAB/Simulink
GitHub Repository:[https://github.com/rdelpoux/ctrl-elec]
Complete Simulink models for motor control examples
Reference implementations and test cases
Documentation and supplementary materials
RCP Platform:[http://rcp.ctrl-elec.fr/]
Rapid Control Prototyping platform documentation
Hardware setup guides for various development boards
Application notes and best practices

Adapting ctrl-elec Examples for MPLAB Blocks

The ctrl-elec examples can be adapted to use MPLAB Device Blocks by:

Replace generic peripheral blocks with MCHP-specific blocks:
Generic PWM → MCHP_PWM_HS_FEP
Generic ADC → MCHP_ADC
Generic encoder → MCHP_QEI
Configure MCHP Master block for target device and enable multi-tasking
Adjust sample times to match MCHP scheduler rates
Enable External Mode using MCHP UART blocks for real-time tuning
Leverage MCHP-specific features:
PWM-triggered ADC for precise current sampling
DMA transfers for high-performance data movement
Assembly code replacement for optimized math operations

Integration Tip: The control algorithms (Clarke/Park transforms, PI controllers, observers) remain identical. Only the peripheral interface blocks need to be replaced with MPLAB-specific blocks. The ctrl-elec documentation provides excellent theoretical background that complements the MPLAB blocks hardware implementation.

Additional Resources

MPLAB Blockset Documentation

[Scheduler and Multitasking] - Configure multi-rate control loops
[External Mode and PIL Testing] - Real-time tuning and verification
[PWM Block Reference] - Motor drive PWM configuration
[ADC Block Reference] - Current and voltage sensing setup
[QEI Block Reference] - Encoder interface for position feedback

Microchip Application Notes

[AN1078] - Sensorless Field-Oriented Control (FOC) for PMSM
[AN1292] - Sensorless Field-Oriented Control of Three-Phase PMSMs
[AN1160] - Sensorless Field-Oriented Control of PMSM Motors
[AN2520] - Field Weakening for PMSM Motor Control

Summary

This guide demonstrated how to implement advanced motor control algorithms using the MPLAB Device Blocks for Simulink, leveraging educational resources from the ctrl-elec project (INSA Lyon).

Key Takeaways:

MPLAB blocks provide hardware-optimized peripheral interfaces for motor control
Field-Oriented Control (FOC) can be implemented using standard Simulink blocks + MCHP PWM/ADC
Sensorless control eliminates encoders using observers, with trade-offs in low-speed performance
Field weakening extends speed range beyond base speed using negative d-axis current
External Mode and PIL testing enable efficient tuning and verification
Multi-rate scheduling optimizes CPU usage for nested control loops

Next Steps:

Visit [ctrl-elec website] for motor control theory tutorials
Download example models from [ctrl-elec GitHub]
Adapt examples using MCHP peripheral blocks for your target device
Use picgui and External Mode for real-time development
Refer to MPLAB blockset documentation for block-specific configuration details

Attribution

Motor control algorithms, theory, and examples presented in this guide are provided by:

ctrl-elec project - Real-time Control & Embedded Systems EducationINSA Lyon (Institut National des Sciences Appliquées de Lyon), France

Website:[https://www.ctrl-elec.fr/]GitHub:[https://github.com/rdelpoux/ctrl-elec]RCP Platform:[http://rcp.ctrl-elec.fr/]

This documentation is part of the MPLAB Device Blocks for Simulink toolbox. The ctrl-elec project and INSA Lyon are independent educational initiatives. Microchip Technology provides the MPLAB blocks hardware interface, while ctrl-elec provides motor control algorithms and educational materials.

⚠️ Third-Party Educational Content

Introduction

Example 1: Field-Oriented Control (FOC) for PMSM

Overview

Control Algorithm Components

Implementation Steps

Key Peripheral Blocks

Example 2: Sensorless Control with Sliding Mode Observer

Overview

Observer Algorithm Components

MPLAB Blocks Configuration

Key Tuning Parameters

Example 3: Field Weakening Control

Overview

Field Weakening Strategy

Implementation with MPLAB Blocks

Tuning Guidelines

Development Workflow with MPLAB Blocks

Step 1: Model Development

Step 2: Simulation and Validation

Step 3: Code Generation and Deployment

Step 4: Real-Time Tuning

Step 5: Performance Optimization

Accessing ctrl-elec Resources

Educational Materials

Adapting ctrl-elec Examples for MPLAB Blocks

Additional Resources

MPLAB Blockset Documentation

Microchip Application Notes

Summary

Attribution

See Also

Application Notes

GitHub

ctrl-elec