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Design platform enables 95% efficiency in air conditioning apps

Posted: 24 Mar 2006 ?? ?Print Version ?Bookmark and Share

Keywords:iMOTION? power design platform? air conditioning? IRMCF3xx? digital control IC?

International Rectifier (IR) introduced a motor control platform for air conditioning applications that is said to enable 95 percent efficiency. The iMOTION integrated power design platform combines IR's proprietary high voltage integrated circuit (HVIC) technology with analog, digital and power building blocks, along with digital control algorithms, for sensor-less motor control applications using DC link phase current sensing.

"The platform provides everything a designer needs to deploy the benefits of variable speed motion control in air conditioners," said Stephen Tsang, senior vice president of Asia sales at IR. This means systems that were once about 60 percent efficient will be more 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."

The air conditioning platform features a proprietary algorithm for interior permanent magnet synchronous motors 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.

Digital section
The product'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, which the company said, eliminates software coding from the development process.

The IRMCF3xx also features an embedded analog signal engine that integrates signal conditioning and conversion circuits for single-current shunt sensor-less control. The MCE executes the sensor-less field oriented control algorithm in about 11s, which is said to be the feature that enables simultaneous control of the fan and compressor motors as well as the PFC circuits.

The IRMCF3xx also includes an application layer processor that defines the operation of the air conditioning system independently from the MCE engine that controls the fan and compressor motors.

Analog section
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 aim to 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.

The new IRS2136D is designed to work with IR's depletion-stop trench IGBTs offered in configurations including discrete and integrated modules. According to IR, trench IGBTs have lower collector-to-emitter saturation voltage, VCE(ON) and total switching loss, ETS than punch-through and non-punch-through IGBTs.

The new iMOTION air conditioner platform is being sampled to qualified users. Pricing varies by power level, configuration and chipset selection. IR claims that a chipset comprising the IRMCF3xx controller and three power stages, controlling the compressor, fan and PFC will enable more than 20 percent savings in the overall air conditioning system. This chipset will cost $19.95 in 100,000 volumes for a system with a 2kW input power rating. Prices are subject to change.

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