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Motor drive ICs use built-in system fault diagnosis to reduce field returns
BridgeSwitch combines high efficiency, design flexibility, enhanced safety, IEC 60335-1 and IEC 60730-1 compliance, with fault diagnosis. By Cristian Ionescu-Catrina, senior marketing manager, Power Integrations
D
esigners are increasingly challenged by demands for continuous improvements in the efficiency and reliability of motor drives in consumer
appliances. From the European Union (EU) to China, higher efficiencies are required for a growing range of consumer appliances including dishwashers, refrigerators, and heating, ventilation and air conditioning (HVAC) systems. Designs are also expected to comply with IEC 60335-1 IEC 60730-1 safety requirements.
At the same time, consumers and manufacturers alike are demanding higher levels of reliability with less field service and fewer returns. According to a recent industry study, misdiagnosis results in 30 per cent of compressor returns having ‘no-fault found,’(1) adding to costs and inefficiencies across the supply chain, and resulting in unhappy consumers. Harnessing the IoT can enable remote monitoring of consumer appliances, but the design must support meaningful and cost-effective fault diagnostics and protection functions. To address these challenges, designers can turn to BridgeSwitch, high-voltage, self-powered, half-bridge motor driver ICs with integrated device protection, and system monitoring and reporting, that deliver higher efficiency, increased design flexibility and enhanced inverter and system reliability (Figure 1).
High efficiency simplifies thermal management
BridgeSwitch integrated half-bridges simplify the development and production of high-voltage inverter driven 1- or 3-phase permanent magnet (PM) or brushless dc (BLDC) motor drives. BridgeSwitch includes a proprietary instantaneous phase current output signal that facilitates the design of sensor-less control schemes. These ICs include two 600V, N-channel power FREDFETs, with high- and low-side drivers, in a small-outline surface mount package (13.6 x 9.4 mm and 1.35 mm high) that offers extended creepage distances and allows heat sinking of both
28 December/January 2023 Components in Electronics
power FREDFETs through the printed circuit board (Figure 2).
The ultra-soft and ultrafast diodes in the FREDFETs are optimized for hard switched inverter drives. The high- and low-side control and drivers are self-supplied, eliminating the need for an external auxiliary power supply. And the distributed thermal footprint, combined with up to 99.2 per cent efficiency, eliminates the need for an external heat sink at rated continuous RMS current, reducing system cost, size, and weight.
Figure 2: This bottom view of the BridgeSwitch InSOP-24C package shows the extended creepage distance (lower right) and the cooling pads for the high- and low-side FREDFETs.
BridgeSwitch ICs can deliver up to 400 W of output power and are well-suited for use in inverters in appliances such as dishwashers and refrigerators, and condenser fans in high efficiency air conditioners.
Hardware-based fault protection saves certification cost and time The microcontroller (MCU) in most inverter designs is used to monitor and respond to fault conditions, as well as controlling the motor. Motor control is straight forward and relatively quick to implement using standard software packages. Fault diagnostics and protection are more challenging and can vary significantly from one application to another since they rely on a variety of different
sensors to monitor the phase currents, system overtemperature conditions, vibration, and other system parameters. It’s complex to program the MCU to interpret the sensor inputs and implement protection as required to gain certification to international standards. Certifying the monitoring and control software is a time consuming and costly process, often delaying time to market. On the other hand, the hardware-based motor fault protection in BridgeSwitch ICs is confirmed to be compliant to the abnormal motor operation requirements of IEC 60335-1 and IEC 60730-1 without relying on software to control, reducing costs and speeding time to market.(2) Its Class A software designation per IEC 60730-1 can save two months of certification time, and the use of BridgeSwitch ICs also simplifies
Figure 1: BridgeSwitch combines high efficiency with extensive fault monitor- ing and reporting (blue text) for increased system and inverter reliability.
Figure 3: BridgeSwitch ICs have integrated fault diagnosis, a bidirectional FAULT bus, plus reporting and hardware protection to enhance reliability.
www.cieonline.co.uk
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