Motor control apparatus and method
AssigneeSevcon Limited
InventorsPeter Barrass, David Hodgson, Howard Slater
Life of this patent
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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 comprises 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.
Claims12
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;
- an indication of the DC voltage, modified based on the comparison;
- for control of the motor control signal based on the motor current data;
- a torque demand modifier configured to modify the torque demand signal based on the modified indication of the DC voltage in the event that the modified indication of the DC voltage is outside a first selected range, and in which the current data provider is configured to provide motor current data based on the modified torque demand signal;
- and
- a current data modifier configured to modify the provided current data based on the difference between the modified torque demand signal and a boundary of a second selected range in the event that the torque demand signal is outside the second selected range.
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;
- the modified indication of the DC voltage;
- modify the torque demand signal based on the modified indication of the DC voltage in the event that the modified indication of the DC voltage is outside a first selected range, and to provide motor current data based on the modified torque demand signal
- modify the provided current data based on the difference between the modified torque demand signal and a boundary of a second selected range in the event that the torque demand signal is outside the second selected range;
- for control of the motor control signal based on the motor current data.
A method of controlling an AC 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;
- modifying the torque demand signal based on the selection signal in the event that the selection signal is outside a first selected range, and selecting the data based on the modified torque demand signal;
- modifying the selected data based on the difference between the torque demand and a boundary of a second selected range in the event that the modified torque demand signal is outside the second selected range;
- and
- controlling the motor control signal in accordance with the selected motor current data.
Dependencies are inferred from the claim text.