Field Oriented Control Algorithm for Sensorless Permanent Magnet Synchronous Motor (PMSM) - Microchip

Microchip is providing free source code for the sensorless Field Oriented Control (FOC) of Permanent Magnet Synchronous Motors (PMSMs), which can operate on any of dsPIC digital motor controller, including the new dsPIC33FJ12MC DSC for Motor Control. Using this FOC platform, motor-driven applications can cost-effectively reduce energy consumption by replacing expensive optical or hall-effect encoders with inexpensive shunt resistors.

Sumit Mitra, Microchip, said:

The Appliance industry is caught in the crossfire between controlling product cost and improving product efficiency…

Microchip is solving this challenge with advanced motor control DSCs at the industry’s lowest price point and free complex algorithms-enabling our customers to achieve rapid product deployment…

The 40 MIPS dsPIC33FJ12MC family cost-effectively provides the DSP functionality required for sensorless FOC, while maintaining the attributes familiar to microcontroller designers, such as deterministic operation and effective interrupt handling. System costs are further reduced by the fact that FOC only requires two current sensors (the third is computed).

Key features of Microchip's FOC algorithm include:

• Only two current sensors are needed
• Source code provides for maximum design flexibility
• FOC transformation blocks, control functions and estimation subroutines optimized for speed
• FOC Application Note AN1078 fully describes concepts and supporting algorithms
• Motor start-up subroutine is included
• Internal variable buffering for Data Monitoring and Control Interface (DMCI) debugging
• Phase advance is available to operate motor above speed limit
• Program code size: 7 Kbytes of Flash memory
• Requires 11 MIPS performance-leaving 75% of available dsPIC DSC MIPS for other functions
• Required RAM size: 400 bytes of data RAM memory

Development Tools
Microchip's FOC algorithm can be evaluated using the dsPICDEM MC1 Motor Control Development Board (part # DM300020) and the dsPICDEM MC1H 3-Phase High Voltage Power Module (part # DM300021). Debugging/programming can be accomplished with the MPLAB ICD 2 In-Circuit Debugger and Device Programmer (part # DV164005).

The MPLAB IDE contains a Data Monitoring and Control Interface (DMCI) to speed product development of FOC applications. DMCI provides dynamic access and control of software variables, and is useful for tuning application parameters and viewing run-time application data graphically. Software parameter changes are updated at run-time, and no recompiling is required between debug sessions.

The free FOC algorithm is available now for downloading, as part of application note AN1078

More info: Microchip Field Oriented Control Algorithm for Sensorless Permanent Magnet Synchronous Motor (PMSM)