System and method for inductance based position encoding sensorless SRM drives
AssigneeThe Texas A&M University System
InventorsMehrdad Ehsani, Suresh Gopalakrishnan
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Abstract
A controller (72) for a switched reluctance machine (20) implements a model of at least one active phase representing dynamic magnetic machine characteristics. The controller (72) determines machine control signals based on rotational position obtained by numerically solving the model with measured machine operating parameters. The model may be implemented as the sum of orthogonal functions relating active phase voltage and current with constants derived from phase inductance to obtain the rotor angle.
Claims13
A method of controlling a multiphase switched reluctance machine comprising:
- measuring the self-inductance of each phase of a plurality of stator phases, the self-inductance of each phase measured at a plurality of points in a phase rotation, the plurality of phases comprising at least one active phase, the self-inductance measured for the at least one active phase comprising a plurality of self-inductances for each active phase;
- constructing a mathematical model of inductance for each phase based on the measured points, the mathematical model representing dynamic magnetic machine characteristics, the mathematical model relating phase voltage to phase rotation angle through phase self-inductance, the mathematical model comprising phase inductance for the at least one active phase;
- measuring the phase current of the at least one active phase of the machine while the machine is in operation;
- determining the phase rotation angle based on the measured phase current and the mathematical model for the at least one measured active phase;
- and
- controlling the machine based on the determined phase rotation angle.
A method of measuring the rotational position of a switched reluctance machine rotor, the method comprising:
- generating a mathematical model based on inductance values measured for each of at least one active phase of a plurality of stator phases, the measured inductance values comprising a plurality of self-inductances for each active phase, the model representing dynamic magnetic machine characteristics, the mathematical model relating at least one measurable machine parameter with rotor rotational position, the mathematical model comprising phase inductance for the at least one active phase;
- measuring the at least one measurable machine parameter during machine operation;
- and
- determining machine rotational position by solving the mathematical model with the at least one measured machine parameter.
A switched reluctance system comprising:
- a switched reluctance machine having a rotor and a plurality of stator phases, each stator phase having a stator phase current;
- a drive switching each stator phase current;
- and
- a controller supplying control signals to the drive, the controller receiving at least one sensed machine parameter, the controller generating control signals based on a rotor position determined from the at least one sensed machine parameter and from a mathematical model based on inductance values measured for at least one active phase of the stator phases, the measured inductance values comprising a plurality of self-inductances for each active phase, the model representing dynamic magnetic machine characteristics, the mathematical model relating the at least one sensed machine parameter with rotor position, the mathematical model comprising phase inductance for the at least one active phase.
Dependencies are inferred from the claim text.