IR’s iMOTION™ Platform Enables Cool Running Air Conditioners

International Rectifier (IR) today during the IEEE Applied Power Electronics Conference introduced a motor control platform for air conditioning applications that enables cool 95 percent efficiency, quieter operation and mechanical simplicity. IR's iMOTION™ integrated power design platform enables energy-saving, variable-speed sinusoidal current control without the need for position sensors for smooth torque output and lower acoustic noise in motors.

The air conditioning platform features a proprietary algorithm for interior permanent magnet synchronous motors (IPMSM) in the compressor as well as the fan, and includes power factor correction (PFC). This, combined with IR's application-specific HVICs and discrete trench IGBTs, achieves 95 percent converter efficiency.

"IR's iMOTION platform is one of the first of its kind to address energy-saving motion control from a systems level. The platform provides everything a designer needs to deploy the benefits of variable speed motion control in air conditioners. This means systems that were once about 60 percent efficient will become better than 90 percent efficient. This is particularly important in places like China where air conditioner usage has grown about four fold – from 8 units to 31 units per hundred households – in the space of five years," said David Tam, vice president of International Rectifier's Energy Saving Products Segment.

iMOTION's digital block consists of the IRMCF3xx family of digital control ICs. These ICs include IR's patented motion control engine (MCE) that implements the complex sensor-less PMSM algorithm in hardware, thus eliminating software coding from the development process. The IRMCF3xx also features an embedded analog signal engine (ASE) that integrates all signal conditioning and conversion circuits for single-current shunt sensor-less control. The MCE executes the sensor-less field oriented control (FOC) algorithm in about 11µs, which is the key feature that enables simultaneous control of the fan and compressor motors as well as the PFC circuits.

The analog block consists of the IRS2136D family of three-phase analog driver and protection ICs. These ICs incorporate three independent 600V half-bridge inverter gate drivers with built-in bootstrap diodes. The protection functions include inverter over-current trip and under-voltage lockout with an automatic fault clear function. These analog gate drivers deliver parameter stability during product lifetime and parameter matching, such as propagation delay for high- and low-side channels, deadtime insertion. Separate power and signal ground connections enable a single dc line configuration on the low-side IGBTs for current sensing. Cross-conduction protection prevents accidental shoot-through to increase inverter reliability.

A chip set comprising the IRMCF3xx controller and three power stages, controlling the compressor, fan and PFC will cost US $19.95 in 100K volumesfor a system with a 2kW input power rating.