Output smoothing in a switched reluctance machine
AssigneeSwitched Reluctance Drives Limited
InventorMichael James Turner
Life of this patent
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Abstract
A switched reluctance machine run as a servo-motor has its torque ripple reduced by shaping the chopping current by which the rotor is rotated relative to the stator. The shaping includes reducing the rate of change of torque with respect to time such that the magnitude of the torque ripple is reduced and therefore more easily rejected by the control function of the machine controller.
Claims26
A method of smoothing the output ripple of a switched reluctance machine comprising a rotor, a stator, and at least one phase winding, the method comprising:
- rotating the rotor relative to the stator;
- monitoring a position parameter of the rotor relative to the stator;
- actively profiling a pulse of phase winding current as a function of rotor position by shaping the leading and trailing edges of the pulse so as to reduce the rate of change of torque with respect to time in each phase inductance cycle, the profiling altering natural current growth and decay in the pulse;
- and
- controlling the profiled phase current with feedback based on the monitored position parameter so as to reduce the overall magnitude of the output ripple of the machine.
A control system for smoothing the output ripple of a switched reluctance machine comprising a rotor, a stator and at least one phase winding, the system comprising:
- means for monitoring a position parameter of the rotor relative to the stator to produce a monitored output;
- means for actively profiling a pulse of phase winding current as a function of rotor position by shaping the leading and trailing edges of the pulse so as to reduce the rate of change of torque with respect to time in each phase inductance cycle, the profiling altering natural current growth and decay in the pulse;
- and
- means for controlling the profiled phase current with feedback based on the monitored output so as to reduce the overall magnitude of the output ripple of the machine.
A system for smoothing the output ripple of a switched reluctance machine comprising a rotor, a stator, and at least one phase winding, the system comprising:
- a monitoring device for monitoring a position parameter of the rotor relative to the stator;
- a profiler for actively profiling a pulse of phase winding current as a function of rotor position by shaping the leading and trailing edges of the pulse so as to reduce the rate of change of torque with respect to time in each phase inductance cycle, the profiling altering natural current growth and decay in the pulse;
- and
- a controller for controlling the profiled phase current with feedback based on the monitored position parameter so as to reduce the overall magnitude of the output ripple of the machine.
Dependencies are inferred from the claim text.