Motor control apparatus and method
AssigneeSevcon Limited
InventorsPeter Barrass, David Hodgson, Howard Slater
Life of this patent
Estimating the term…
Abstract
An apparatus for controlling an AC power supply for an electric motor, said AC power supply being derived from a DC voltage. The apparatus including a comparer configured to provide a comparison of a modulation index of a motor control signal with a reference value. This current data provider is configured to provide current data based on a torque demand signal; a speed signal indicating the speed of rotation of the AC motor; and an indication of the DC voltage modified on the comparison for control of the motor control signal which is based on the motor current data.
Claims27
An apparatus for controlling an AC power supply for an electric motor, said AC power supply being derived from a DC voltage, the apparatus comprising:
- a comparer configured to provide a comparison of a modulation index of a motor control signal with a reference value;
- and
- a current data provider, configured to provide current data based on:
- a torque demand signal;
- a speed signal indicating the speed of rotation of the AC motor;
- and
- an indication of the DC voltage, modified based on the comparison;
- for control of the motor control signal based on the motor current data.
The apparatus of any preceding claim comprising a data store comprising a plurality of associations arranged to associate each of a plurality of current data elements with a respective:
- motor speed,
- torque demand, and
- DC voltage;
- wherein the data provider is configured to provide the current data by selecting amongst the stored data elements based on the associations.
An apparatus for controlling an AC power supply for an electric motor, said AC power supply being derived from a DC voltage, the apparatus comprising:
- a processor configured to:
- compare a modulation index of a motor control signal with a reference value;
- modify an indication of the DC voltage based on the comparison;
- provide current data based on:
- a torque demand signal;
- a speed signal indicating the speed of rotation of the AC motor;
- and
- the modified indication of the DC voltage;
- for control of the motor control signal based on the motor current data.
The apparatus of any preceding claim in which the current data comprises a direct phase current information, and quadrature phase current information.
The apparatus of any preceding claim in which the modulation index of the control signal comprises the ratio of the motor control signal amplitude to one of:
- (a) a maximum amplitude value of a controller that provides the motor control signal;
- or (b) the amplitude of a timing signal used to determine a PWM signal from the motor control signal.
The apparatus of any preceding claim further comprising a motor controller adapted to provide the motor control signal based on the current data.
A method of controlling a power supply for an AC motor, said AC power supply derived from a DC voltage, the method comprising:
- selecting data from stored motor current data based on:
- a torque demand signal;
- a speed signal indicating the speed of rotation of the AC motor;
- and
- a selection signal based on the DC voltage and a comparison between a reference value and a modulation index of a motor control signal;
- and
- controlling the motor control signal in accordance with the selected motor current data.
An apparatus substantially as described herein with reference to the accompanying drawings.
A method substantially as described herein with reference to the accompanying drawings.
Dependencies are inferred from the claim text.