Position sensor elimination technique for the switched reluctance motor drive
First Claim
1. An indirect method for estimating instantaneous rotor position in a switched reluctance motor having multiple stator phases which are energized in synchronism with rotor position, said method comprising the steps of:
- (a) generating a periodic signal having a frequency and a period responsive to phase inductance of said motor, said period being a reciprocal of said frequency, and(b) estimating the instantaneous rotor position from said periodic signal.
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Abstract
Rotor position information for a switched reluctance (SR) motor drive is obtained indirectly in response to the motor phase inductance. An oscillator generates a signal having a time period that is a function of the inductance. The signal is processed by other circuits to obtain proper instants of commutation. In the preferred motor drive, the energized phase windings are isolated from the oscillator, and periodic signals are obtained which have periods indicating the phase inductances of the unenergized phase windings. The periods are compared to threshold values to obtain position indicating signals, and commutating signals are derived from the position indicating signals.
57 Citations
20 Claims
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1. An indirect method for estimating instantaneous rotor position in a switched reluctance motor having multiple stator phases which are energized in synchronism with rotor position, said method comprising the steps of:
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(a) generating a periodic signal having a frequency and a period responsive to phase inductance of said motor, said period being a reciprocal of said frequency, and (b) estimating the instantaneous rotor position from said periodic signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for estimating instantaneous rotor position in a switched reluctance motor having multiple stator phase windings which are energized in synchronism with rotor position, said apparatus comprising:
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means for generating a periodic signal having a frequency and a period responsive to said phase inductance of said motor, said period being a reciprocal of said frequency, and means for estimating the instantaneous rotor position from said periodic signal. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. Apparatus for energizing multiple stator phase windings of a switched reluctance motor in synchronism with rotor position, said stator phase windings having phase inductances responsive to said rotor position, said apparatus comprising:
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oscillators connected to stator phase windings of said motor for generating periodic signals having respective frequencies responsive to said phase inductances; frequency discriminators connected to said oscillators for providing rotor position indicating signals in response to said periodic signals; logic circuits connected to said frequency discriminators for providing respective commutating signals from said rotor position indicating signals; and power circuits connected to said logic circuits and responsive to said commutating signals for selectively energizing said multiple stator phase windings in synchronism with said rotor position.
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Specification