Optocouplers For Variable Speed Motor Control Electronics In Consumer Home Appliances White Paper

Thus, the design of a low-cost, reliable, efficient, variable speed three-phase motor has become a prime focus for both appliance designers and electronic component manufacturers. The components needed for the three-phase motor electronics include IGBTs, gate drivers, inverters, microcontroller units, analog current and voltage sensors, among others. Modern, state-of-the-art, low cost, reliable optocouplers (optoisolators) are becoming designers’ preferred component for optically isolated gate drivers and optically isolated analog current and voltage sensors.

Three-Phase Variable-Speed Motor Control Topology

Modern three-phase variable-speed motor control architecture can be divided into subsystems or components. The key components of this topology include IGBT/ MOSFET three-phase inverters (Q1, Q2, Q3, Q4, Q5, Q6), single-phase or three-phase rectifier diode bridge, gate drivers, analog current and voltage sensors, isolated and ground-referenced power supplies, and of course, the microcontroller unit.

Because of the presence of high power, high voltages, and high currents in the design of a motor, it is necessary, and often mandated by safety and regulatory agencies, that people operating the motors and low power digital electronics are protected through some form of safe galvanic isolation.

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