Home appliances become more efficient with new ICs

Trends in appliance motors
Permanent magnet synchronous motors are beginning to replace split-phase induction motors in appliances as a means of boosting efficiency while reducing part costs. PM synchronous motors work at variable speeds and may become part of the appliance structure itself, perhaps eliminating the need for separate gearboxes and belt drives used to harness power from induction motors. Component IRMC xxx family through USBid

Integrated chips in PMS motors
Integrated circuits aimed at managing motors and power supplies may help boost the efficiency of
consumer goods such as air conditioners, washer/dryers, refrigerators, and video games. Special interface chips for appliances and switching power supplies that facilitate the use of advanced motors and controls can all be found through USBid. One new chip targets permanent-magnet synchronous (PMS) motors that are now being designed into major appliances. These motors are starting to be specified in place of ordinary split-phase induction motors, which have served in washer/dryers and refrigerators for decades. Besides being more energy efficient, PMS motors are smaller than comparable induction motors and less expensive as well because they use less steel. PMS motors have also begun showing up in condensing units of split-system residential air conditioners. There is also a single-rotary compressor incorporating a PMS motor that is said to be as efficient as more-expensive scroll compressors. The chipmakers are targeting motors in condensing units specifically with the development of what it calls an iMotion integrated power-design platform. It lets appliance makers control PMS motors with variable-speed sinusoidal current control. This control technique eliminates the need for Hall-effect sensors that would ordinarily be necessary to gauge rotor position. The platform, dubbed the IRMCxx family and can ordered through USBid, is billed as an IC, complete with power-factor correction. The only feedback it needs for operation comes from a dc link-current sensor. It runs embedded motor-control algorithms with an independent application layer processor that handles tasks specific to different classes of appliances. The chip can be keyed to different kinds of appliances through the use of appliance-specific high-voltage IC sections and intelligent power modules already in place.

Integrated chips used in air conditioners
For example, the air-conditioning platform incorporates a proprietary algorithm for interior PMS motors driving both the AC compressor and fan. Combined with application-specific HVICs and discrete trench IGBTs to handle the output power, the controller is said to hit 95% converter efficiency. In this regard it works with individual PMS motor manufacturers to tune converter parameters for best efficiency. Digital controls on the chips consist of a Motion Control Engine (MCE) that implements the sensorless algorithm in hardware, plus an embedded analog signal engine that handles all signal-conditioning and conversion circuits for single-current shunt sensorless control. The MCE executes the sensorless field-oriented control algorithm in about 11 _sec. This speedy execution is key to handling fan and compressor motors simultaneously. An application layer processor on the chip defines the operation of the air-conditioning system independently from the MCE that controls the fan and compressor motors. The intent of this separate processor is to let appliance makers focus on application issues rather than on motor control. Appliance makers may locate the PMS chips (IRMC) through Get Parts Fast a USBid, Inc. sourcing site.