Reference Design
Motor Control System
A complete reference design for building production-ready motor control systems with field-oriented control, multi-motor support, and comprehensive safety features for industrial and automotive applications.
Introduction
What This Reference Design Is About
This motor control reference design provides a complete blueprint for developing high-performance motor drive systems for electric vehicles, industrial machinery, and robotics applications. It demonstrates our proven approach to achieving precise torque and speed control while maximizing efficiency.
The design covers everything from power stage design and current sensing to advanced control algorithms and safety systems—enabling smooth, efficient motor operation across various motor types and applications.
Requirements
- Performance: Field-Oriented Control with >97% efficiency
- Control Loop: 20kHz PWM with 10µs current loop execution
- Motor Types: PMSM, BLDC, ACIM, SRM support
- Safety: IEC 61800-5-2 Safe Torque Off (STO) compliant
- Power Range: 100W to 100kW scalable design
Recommended Architecture
Integrated motor control architecture with clear separation of control and power stages:
- • Control Board: DSP/MCU with dedicated motor control peripherals
- • Gate Driver: Isolated gate drivers with desaturation protection
- • Power Stage: IGBT/SiC MOSFET inverter with integrated sensing
- • Current Sensing: Hall-effect or shunt-based phase current measurement
- • Position Feedback: Resolver, encoder, or sensorless estimation
Essential Parts of This Design
- • Three-phase inverter with SiC/IGBT power modules
- • Field-Oriented Control (FOC) algorithm implementation
- • Space Vector Modulation (SVM) for optimal switching
- • Position and speed estimation (sensorless capability)
- • DC bus voltage and current monitoring
- • Regenerative braking with energy recovery
- • Thermal management and derating
- • CAN/EtherCAT communication for system integration
This reference design serves as a customizable foundation—adapt it to your specific motor type, power level, and application requirements.
Hardware
Recommended Platform: Joshua
Joshua Platform (TI Sitara AM263x) is our recommended platform for high-performance motor control applications.
Why Joshua:
- • Dedicated motor control PWM peripherals (EPWM)
- • Hardware trigonometric accelerator for FOC
- • Sigma-delta filter for high-resolution current sensing
- • Real-time PRU-ICSS for deterministic I/O
- • EtherCAT slave support for industrial connectivity
Key Specifications: 400MHz ARM Cortex-R5F, 12-bit ADCs at 4MSPS, 16 EPWM channels
Essential Components to Add
Components added to baseline Joshua platform:
- • Gate Drivers: TI UCC21750 isolated gate driver with desat protection
- • Power Module: Infineon EasyPIM 3B (IGBT) or Wolfspeed CAS120M12BM2 (SiC)
- • Current Sensors: LEM GO 50-SME or shunt with isolation amp
- • Resolver Interface: AD2S1210 resolver-to-digital converter
- • DC Bus Sensing: Isolated voltage divider with AMC1311
- • Safety Relay: Safe Torque Off (STO) relay module
- • EMI Filter: Common-mode choke and X/Y capacitors
Schematic Capture & PCB Layout
Design Tools: Altium Designer with power electronics component libraries
PCB Stack-up: 4-layer design with 2oz copper for power paths
Key Considerations:
- • Low-inductance gate drive loops (<10nH)
- • Kelvin connections for current shunts
- • Thermal design for power dissipation
- • EMC filtering and layout optimization
Regulatory Requirements
Functional Safety:
- • IEC 61800-5-2 for drive safety functions
- • ISO 26262 ASIL-D for automotive applications
- • IEC 61508 SIL3 for industrial applications
EMC Standards:
- • IEC 61800-3 for EMC compliance
- • CISPR 11 for industrial environments
Product Safety: IEC 62477-1 for power electronics
RTOS/Operating System
Recommended OS: RTOS
TI-RTOS or FreeRTOS is recommended for motor control applications requiring deterministic real-time performance.
Why RTOS over Linux:
- • Deterministic timing for control loops (10µs guaranteed)
- • Direct hardware access for PWM and ADC
- • Minimal interrupt latency (<1µs)
- • Small footprint for cost-effective MCUs
- • Simpler safety certification path
When Linux May Be Needed
Consider Linux for:
- • Rich HMI with touchscreen and graphics
- • Cloud connectivity and data analytics
- • Multi-axis coordination with complex kinematics
- • Integration with ROS for robotics applications
Hybrid Approach: RTOS on dedicated motor control MCU + Linux on application processor for HMI and connectivity.
Real-Time Requirements
Control Loop Timing:
- • Current loop: 20kHz (50µs period)
- • Speed loop: 2kHz (500µs period)
- • Position loop: 1kHz (1ms period)
Interrupt Priorities:
- • Fault interrupt: Highest (NMI)
- • PWM/ADC interrupt: High
- • Communication: Medium
- • Background tasks: Low
Device Drivers
Custom Drivers Developed:
- • EPWM driver with dead-time and trip zones
- • Sigma-delta ADC driver for current sensing
- • QEP/resolver interface driver
- • EtherCAT slave stack driver
- • Safety I/O driver for STO functions
Hardware Accelerators: Trigonometric Math Unit (TMU) for sine/cosine and Park/Clarke transforms
Middleware
Recommended Middleware: EtherCAT
EtherCAT (CoE) is recommended for industrial motor control applications requiring synchronized multi-axis control.
Why EtherCAT:
- • Deterministic communication with <1µs jitter
- • Distributed clocks for synchronized motion
- • CANopen over EtherCAT (CoE) profile support
- • Wide industry adoption in automation
Regulatory Considerations
Industrial Protocols:
- • CiA 402 drive profile (CANopen/EtherCAT)
- • IEC 61800-7 for drive system interfaces
Safety Communication:
- • FSoE (Fail Safe over EtherCAT)
- • CIP Safety for EtherNet/IP systems
- • PROFIsafe for PROFINET systems
Middleware Interfaces
Motion Interface:
- • Position/velocity/torque modes
- • Cyclic synchronous modes (CSP/CSV/CST)
- • Homing and profile modes
- • Interpolated position mode
Status & Diagnostics:
- • Drive state machine (CiA 402)
- • Fault codes and error history
- • Temperature and current monitoring
- • Performance counters
Configuration:
- • Motor parameters (Rs, Ls, Ke)
- • Control loop gains
- • Protection limits
- • Auto-tuning parameters
Application
Application Architecture
RTOS-based Firmware with interrupt-driven control loops and background task processing.
Architecture Pattern: Layered architecture with hardware abstraction, control algorithms, and application logic.
Design Decision: C with fixed-point math for control loops, floating-point for configuration and monitoring.
Core Application Modules
- • FOC Engine: Park/Clarke transforms, PI regulators, SVM generation
- • Position Estimator: Sensorless observer or encoder/resolver processing
- • Speed Controller: Anti-windup PI with feedforward
- • Flux Weakening: Extended speed range operation
- • Protection Manager: Overcurrent, overvoltage, thermal protection
Development Tools
Essential Tools:
- • TI Code Composer Studio for development
- • MATLAB/Simulink for algorithm design
- • Motor Control Workbench for tuning
- • Oscilloscope with math functions
Testing Tools:
- • Dynamometer for load testing
- • Power analyzer for efficiency measurement
- • HIL simulator for safety testing
Diagnostics & Security
Log Management & Debugging:
- • Real-time data streaming via high-speed serial
- • Fault event logging with timestamps
- • Parameter recorder for tuning
OTA & Security:
- • Secure boot for firmware integrity
- • Encrypted parameter storage
- • Firmware update via fieldbus
Other Essential Supporting Apps
Cloud Integration
- • Fleet Monitoring: Drive health and performance across installations
- • Predictive Maintenance: Bearing wear and thermal degradation prediction
- • Energy Analytics: Efficiency optimization and energy consumption tracking
- • OTA Updates: Remote firmware updates with safety validation
Desktop Applications
- • Auto-Tuning Tool: Automatic motor parameter identification and loop tuning
- • Scope Tool: Real-time waveform visualization for debugging
- • Configuration Tool: Drive parameterization and commissioning
- • Analysis Tool: Post-mortem fault analysis and logs
Web-Based Apps
- • Commissioning Portal: Web-based drive setup and configuration
- • Monitoring Dashboard: Real-time drive status and KPIs
- • Documentation: Interactive parameter documentation
- • Support Portal: Remote diagnostic access for service
Our Experience
Products Delivered
Using this reference design, we have successfully delivered:
- EV Traction Inverter: 150kW SiC-based inverter for electric vehicle propulsion with 98% peak efficiency
- Industrial Servo Drive: Multi-axis servo system with EtherCAT connectivity for CNC machines
- Compressor Drive: Variable frequency drive for HVAC compressors with sensorless control
Key Achievements
>97%
Peak Efficiency
SIL3
Safety Rating
20kHz
Switching Frequency
150kW
Max Power Rating
Our motor control reference design has been deployed in thousands of drives across automotive, industrial, and commercial applications.