High voltage motor driver

Produces clean and stable 390VDC to motor control sub-system

There are motors and motor control all around us. In this design, Rensas highlights a high-voltage motor application suitable for appliances, HVAC compressors and fans, etc. They combine power factor correction (PFC), now required by many power providers, to produce a clean and stable 390VDC to the motor control sub-system. The heart of the motor control is a 32 bit high-performance RISC processor, the 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 below, we are showing hardware to support sensor-less 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 (85-240VAC)
• 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 (1uS) with multi S/H to simplify motor phase current sampling
• Efficient FOC algorithm that leaves plenty of MCU cycles for other tasks (communication typical)