Sensorless sinusoidal three-phase gate controller improves motor performance
The controller is designed to provide the motor control functions in a system where a small microcontroller provides the communication interface to a central ECU and intelligent fault and status handling. The A4964 provides the supply and watchdog for the microcontroller and the high-voltage interfaces between the microcontroller and the central ECU and ignition switch. It can also operate as an independent single chip remote motor controller.
The motor is driven using a three-phase sinusoidal current drive where phase commutation is determined, without the need for independent position sensors, by monitoring the motor back-EMF (bemf). The sensorless start-up scheme includes forward and reverse pre-rotation (windmill) detection and synchronization, and allows the device to operate over a wide range of motor and load combinations.
The A4964 offers three control modes, open loop (voltage) control, current (torque limit) control, and closed-loop speed control which allows it to be used in a wide range of applications. Control mode, operating mode, and bridge parameters are programmed through an SPI-compatible serial interface. A single current sense amplifier provides peak current limiting and average current measurement through the serial interface. Integrated diagnostics provide indication of under-voltage, over-temperature, and power bridge faults and can protect the power switches under most short-circuit conditions.
The A4964 comes in both a 36-terminal QFN and a 32-lead QFP package, both with exposed thermal pad for enhanced power dissipation.
Allegro MicroSystems; www.allegromicro.com
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