SPRACT7 August   2020 TMS320F280021 , TMS320F280021-Q1 , TMS320F280023 , TMS320F280023-Q1 , TMS320F280023C , TMS320F280025 , TMS320F280025-Q1 , TMS320F280025C , TMS320F280025C-Q1 , TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2Fundamental Theories of FOC and Current Measurement
    1. 2.1 Basic Theory of FOC
    2. 2.2 Current Sensing Technique
      1. 2.2.1 Low-Side Current Measurement
        1. 2.2.1.1 Three-Shunt Current Sensing
        2. 2.2.1.2 Dual-Shunt Current Sensing
        3. 2.2.1.3 Single-Shunt Current Sensing
  5. 3Implementation of Single-Shunt Phase Current Reconstruction
    1. 3.1 Duty Cycle Compensation
    2. 3.2 PWM Phase Shift Compensation
    3. 3.3 Current Reconstruction
  6. 4Sensorless FOC With Single-Shunt Measurement
  7. 5Hardware Consideration for Single-Shunt Current Sensing
    1. 5.1 Slew Rate
    2. 5.2 Current Sensing Circuit
  8. 6Test Results
  9. 7Summary
  10. 8References

7 Summary

This application report discussed Sensorless Field Oriented Control of a Permanent Magnet Synchronous Motor with a single-shunt dc link current measurement. The single-shunt measurement technique is suitable for cost-sensitive or PCB space-sensitive applications. This document showed the PWM compensation method and current reconstruction technique to get three-phase motor current with a single dc-link current sensor.

It was also verified that the PWM phase shift compensation method that causes minimum distortion on the output voltage matches well with InstaSPIN-FOC that requires output phase voltage to be measured by ADC. This solution also can be applicable to other sensorless FOC such as TI’s eSMO solution. This solution was implemented and verified with F28004x and DRV8312EVM based on MotorControl SDK. Since the reference code was implemented with floating-point, other C2000 Generation 3 MCUs such as F28002x can be also well matched.