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dsPIC33 Refrigerator Compressor Reference Design

Part Number: dsPIC33_refrigerator_board

Summary:

Refrigerator compressors are now driven by brushless DC motors or permanent magnet synchronous motor to meet high energy efficiency ratings. You must use an inverter-based variable speed drive for the brushless motor to achieve this high energy efficiency. The variable speed drive allows you to operate the compressor at an optimal speed in order to maintain a constant temperature setting as

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Product Features

    • Rated Power: 250W
    • Peak Power: 350W
    • Voltage: 187-264V
    • Supports compressors with either IPMSM or SPMSM
    • Single-shunt current sensing technique using on-chip Op Amps on the dsPIC® DSC
    • Motor Control Algorithms:
      • Sensorless Field Oriented Control (FOC)
      • Angle-Track Phase Locked Loop (ATPLL)
      • Maximum Torque Per Ampere (MTPA)
      • On-the-Fly startup (Multiple startup)
      • Stall detection with auto-recovery from failed start up
    • Protection:
      • Over-current
      • Over-voltage
      • Under-voltage
      • Speed error
      • In-rush current limit
      • Stall detection
    • Two UART ports, one isolated and one non-isolated 
      • Connect to X2C Scope for real time data visualization and debugging
    • Frequency input interface to control motor speed using a square wave signal

Summary

Refrigerator compressors are now driven by brushless DC motors or permanent magnet synchronous motor to meet high energy efficiency ratings. You must use an inverter-based variable speed drive for the brushless motor to achieve this high energy efficiency. The variable speed drive allows you to operate the compressor at an optimal speed in order to maintain a constant temperature setting as compared to a fixed-speed single-phase AC induction motor (ACIM) drive. Field-Oriented Control (FOC) of brushless motors enables you to implement the variable speed drive and add advanced motor control features like on-the-fly startup and stall detection with auto-recovery.

This refrigerator compressor reference design will help you to rapidly prototype and develop a cost-effective design using a dsPIC® Digital Signal Controller (DSC). The design is suitable for a variety of compressor motor types, supporting both Interior Permanent Magnet Synchronous Motors (IPMSM) and Surface Mount Permanent Magnet Synchronous Motors (SPMSM). This reference design implements sensorless control and single-shunt current sensing technique to save BOM cost. This design also addresses the challenges of reliable startup of the compressor with high pressure and low standby power consumption.

Microchip provides Class-B Safety Software libraries for the dsPIC33 to reduce your development time for appliances requiring functional safety.

Ready for a live demonstration? Please contact Microchip’s local sales office in your geography to request a demonstration. This reference design is provided with full user’s guide, source code, schematics and PCB layout.

Benefits

  • Speeds development time with turnkey example design including rich protection features, motor control and application source code, user guide, multiple communication ports
  • Reduces system level BOM cost due to high-performance core and control peripherals enabling sensorless FOC, low cost auxiliary power supply, and single-shunt current sensing with on-chip Op Amps
  • Supports a power range for most home refrigerators and can be easily optimized for your application
  • Provides smoother torque and better start and stop characteristics using Field Oriented Control (FOC) which enables a quieter compressor operation and a longer lifespan
  • Implements motor control techniques for a reliable start up in the presence of high compressor pressure
  • Saves power with low standby current consumption