Compensation for variable voltage
AssigneeSwitched Reluctance Drives Limited
InventorsMichael Leo McClelland, Jonathan Richard Quinn
Life of this patent
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Abstract
A switched reluctance drive is supplied from a voltage source which varies from the voltage at which the control laws for the drive were determined. The control system compensates for this by modifying both the speed and torque values used to determine the correct firing angles for the demanded load. The system works over a very wide range of voltage variation and is independent of the shape of the torque/speed curve of the drive.
Claims25
A method of compensating for deviations in actual DC link voltage from a reference DC link voltage in an electric drive system including a machine controller that controls a machine in response to a torque demand signal, the machine including a rotor and a stator having windings, the rotor rotating at an actual rotor speed during operation of the machine, wherein the machine controller selectively applies the actual DC link voltage to the stator windings, the method comprising:
- sampling the actual DC link voltage;
- sampling the actual rotor speed;
- determining a compensated speed signal using the actual DC link voltage;
- determining a compensated torque demand signal using the actual DC link voltage;
- and
- using the compensated speed and torque demand signals to control application of the actual DC link voltage to the stator windings.
A system for compensating for deviations in actual DC link voltage from a reference DC link voltage in an electric drive system including a machine controller that controls a machine in response to a speed signal, the machine including a rotor and a stator having windings, the rotor rotating at an actual rotor speed during operation, wherein the machine controller selectively applies the actual DC link voltage to the stator windings, the system comprising:
- means for sampling the actual DC link voltage;
- means for sampling the actual rotor speed;
- means for determining a compensated speed signal using the actual DC link voltage;
- means for determining a compensated torque demand signal using the actual DC link voltage;
- means for transmitting the compensated speed signal and the compensated torque demand signal to the machine controller;
- and
- means for using the compensated speed and torque demand signals to control application of the DC link voltage to the stator windings.
A computer program on a computer readable medium for use in a system for compensating for deviations in actual DC link voltage from a reference DC link voltage in an electric drive system that includes a machine controller that controls a machine in response to a speed signal, the machine including a rotor and a stator having windings, the rotor rotating at an actual rotor speed during operation, wherein the machine controller selectively applies the actual DC link voltage to the stator windings and the machine further comprises means for sampling the actual DC link voltage and means for sampling the actual rotor speed, wherein the computer program comprises instructions for:
- determining a compensated speed signal using the actual DC link voltage;
- determining a compensated torque demand signal using the actual DC link voltage;
- and
- using the compensated speed and torque demand signals to control application of the DC link voltage to the stator windings.
Dependencies are inferred from the claim text.