The reference design enhances refrigerator efficiency and reliability by enabling advanced compressor control for modern refrigeration systems.
Refrigerator compressors have transitioned to using brushless DC motors or permanent magnet synchronous motors for higher energy efficiency. An inverter-based variable speed drive is essential for these brushless motors, allowing the compressor to operate at optimal speeds and maintain a constant temperature more efficiently than traditional fixed-speed single-phase AC induction motor (ACIM) drives. Field-oriented control (FOC) with brushless motors enhances the implementation of variable speed drive. It adds advanced motor control features like on-the-fly startup and stall detection with auto-recovery.
Microchip’s reference design for a refrigerator compressor is specifically created to aid in rapidly prototyping and developing a cost-effective, innovative solution using a dsPIC33EP64MC202 Digital Signal Controller. This design integrates key Microchip components, such as an MCP16331 DC/DC converter and a MIC5239 LDO voltage regulator. It’s designed with versatility in mind, ensuring compatibility with a broad range of refrigerator compressor motors. This includes Interior Permanent Magnet Synchronous Motors (IPMSM) and Surface Mount Permanent Magnet Synchronous Motors (SPMSM).
The design stands out for its sensorless control and single-shunt current sensing technique, effectively reducing the Bill of Materials (BOM) costs. Moreover, it tackles the challenges commonly faced with the reliable startup of compressors under high pressure and is engineered to maintain low standby power consumption. This makes it an ideal solution for modern refrigeration systems that require efficient and dependable compressor operation.
This design is helpful for engineers developing Permanent Magnet Synchronous Motor (PMSM) compressor control applications using dsPIC Digital Signal Controllers (DSCs). It is crafted to offer a competitive, sensorless control solution suitable for IPMSM and SPMSM compressors, including hardware and software components.
The design’s continuous output current is rated at 0.65A (RMS), supporting approximately 250W of continuous output power. This output is achievable when operating from a 187V to 264V single-phase input voltage in a room-temperature environment. The peak output power reaches 350W for high compressor pressure operations.
The design operates on a 220 Volt Alternating Current (AC) from the grid and controls the compressor motor using a dsPIC33EP64MC202 Digital Signal Controller (DSC). The 220V AC input voltage goes through the filter and protection circuitry and is then converted to direct current (DC) voltage by the rectifier circuit. An auxiliary power supply circuit provides non-isolated 15- and 3.3 Volt voltages to the Microcontroller Unit (MCU), feedback circuitry, and the three-phase inverter bridge circuit.
Key functional modules in the reference design include an Electromagnetic Interference (EMI) filter and protection module, a Rectifier, an Auxiliary power supply, a Microcontroller Unit (MCU), an Inverter, Feedback circuitry, and Communication ports.
Microchip has tested this reference design. It comes with a Bill of Material BOM, schematics, etc. You can find additional data about the reference design on the company’s website. To read more about this reference design, click here.
