Apparatus and method for providing information relating to a motor
AssigneeCity University of Hong Kong
InventorShu Yuen Ron Hui
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Abstract
This invention relates to an apparatus and method for deriving speed and position information for an electric motor. Apparatus for and a method of controlling a motor 100 are also disclosed. The apparatus for providing information relating to the operation of an electrical motor 100 comprises a sampler 50, 51 for sampling the instantaneous motor current is and a processor 160 for determining the instantaneous rate of change of the motor current and providing information about the motion or position of said motor based on said instantaneous rate of change of the motor current. In this way speed and position information can be provided, at low speeds, and without using a speed sensor.
Claims18
Apparatus for providing information relating to the operation of an electrical motor;
- comprising a sampler for sampling an instantaneous motor current is and a processor for determining an instantaneous rate of change of the motor current and providing information about the motion or position of said motor based on said instantaneous rate of change of the motor current, wherein the sampler has a sampling rate, said sampling rate having a frequency greater than or equal to a switching frequency of an inverter arranged to drive the motor.
A method of determining information relating to operation of a motor comprising the steps of
- a) sampling a plurality of instantaneous motor current values;
- b) determining an instantaneous rate of change of the motor current based on said current values;
- c) calculating information about motion or position of said motor based on said instantaneous rate of change of the motor current,
- d) switching an inverter between a plurality of switching states to provide current to the motor and sampling the instantaneous motor current at a frequency equal to or greater than the frequency at which the inverter switches between switching states.
Dependencies are inferred from the claim text.