Motor controller for determining a position of a rotor of an AC motor, AC motor system, and method of determining a position of a rotor of an AC motor

Abstract

A motor controller (4) for determining a position of a rotor (9) of an AC motor, the motor controller comprises a control input (12) for receiving a control signal, an output (13) for providing a power control signal for controlling power applied to a stator (7) of the AC motor, and an input (14) for receiving a feedback signal representative of the current in the stator. The control input (12) and output (13) are coupled by a reference path, and the input (14) is coupled to the control input (12) by a feedback path. A carrier signal injection element (42) injects a high frequency carrier signal in the reference path at an injection node. The motor controller (4) is arranged to generate the power control signal in dependence on the control signal, the feedback signal, and the high frequency carrier signal. A position determining element (18) generates a position signal representing the position of the rotor in dependence on the feedback signal which includes a carrier signal componentcomprising rotor position information. The motor controller (4) further comprises a filter block (39) coupled between the control input (12) and the injection node in the reference path for filteringsignals in the reference path in a frequency range including the frequency of the high frequency carrier signal.

Description

technical field [0001] The present invention relates to a motor controller for determining the position of a rotor of an AC motor and a method of determining the position of the rotor of an AC motor. Background technique [0002] AC motors are widely used in many applications, including consumer applications such as washing machines, dishwashers, electric fans, and vehicle applications such as window regulator controls, electric power steering systems, electromechanical braking systems, and the like. [0003] An AC motor system typically includes a motor including a stator and a rotor, and a motor controller for controlling the power provided to drive the motor. To ensure good control of the motor, for example to meet specific motor performance requirements, the motor controller needs to know the position of the motor rotor. [0004] Position sensors, such as position and speed transducers, and the cables and connectors required by such sensors add to the size, weight, and ...

AI Technical Summary

Problems solved by technology

Known sensorless control methods do not take into account the interference caused between high frequency components carrying salient pole position information and high frequency harmonic components generated in the control loop

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