There are motors and motor control all around us. In this design, we highlight a high-voltage motor application suitable for appliances, HVAC compressors and fans, etc. We combine power factor correction (PFC), now required by many power providers, to produce a clean and stable 390VDC to the motor control sub-system. At the heart of the motor control is a 32-bit high performance RISC processor, the Renesas RX23T, containing a floating point unit (FPU) to simplify the algorithm implementation. Utilizing a 3-phase timer with complementary outputs, the RX23T supports a wide variety of algorithms that can be downloaded. In this particular block diagram, we are showing hardware to support sensorless field oriented control (FOC) utilizing multi-shunt phase-current sampling.

Key Features

  • Single-phase PFC boost controller to provide stable bus voltage (390VDC) for the system
  • Universal input voltage support (85VAC - 240VAC)
  • Power factor as high as 0.999, efficiency up to 98%
  • High performance op amps for conditioning the shunt voltage for fast sampling
  • High-speed ADC (1µS) with multi S/H to simplify motor phase current sampling
  • Efficient FOC algorithm that leaves plenty of MCU cycles for other tasks (communication typical)
System Block Diagram

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