Electronic commutation method and related apparatus
First Claim
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1. A method of controlling an electronically commutated motor having multiple phase windings by applying PWM drive signals in accordance with a series of commutation states, where a commutation event occurs when a rotor moves from a position associated with one commutation state to a position associated with another commutation state, the method comprising the steps of:
- (a) applying PWM drive signals at a set frequency on a cyclical basis;
(b) responsive to occurrence of a commutation event that is asynchronous with and occurs during an ongoing PWM drive signal cycle at the set frequency, increasing the frequency of PWM drive signals applied during the ongoing PWM drive signal cycle to a frequency above the set frequency in order to reach the end of the ongoing PWM drive signal cycle more quickly than without such a frequency increase; and
wherein the set frequency is X, in step (b), the frequency is increased to a frequency Y and, after completion of the ongoing PWM drive signal cycle at frequency Y, the frequency is subsequently decreased to a frequency Z, which is greater than X and less than Y.
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Abstract
A method and apparatus for electronic commutation of a pulse width modulation (PWM) controlled motor involves temporarily increasing the frequency of one or more PWM drive signals applied to the motor upon the occurrence of an asynchronous commutation event.
14 Citations
17 Claims
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1. A method of controlling an electronically commutated motor having multiple phase windings by applying PWM drive signals in accordance with a series of commutation states, where a commutation event occurs when a rotor moves from a position associated with one commutation state to a position associated with another commutation state, the method comprising the steps of:
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(a) applying PWM drive signals at a set frequency on a cyclical basis; (b) responsive to occurrence of a commutation event that is asynchronous with and occurs during an ongoing PWM drive signal cycle at the set frequency, increasing the frequency of PWM drive signals applied during the ongoing PWM drive signal cycle to a frequency above the set frequency in order to reach the end of the ongoing PWM drive signal cycle more quickly than without such a frequency increase; and wherein the set frequency is X, in step (b), the frequency is increased to a frequency Y and, after completion of the ongoing PWM drive signal cycle at frequency Y, the frequency is subsequently decreased to a frequency Z, which is greater than X and less than Y. - View Dependent Claims (2, 3, 4, 5)
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6. A method for operating a motor control system in which motor phase windings are energized by PWM drive signals in accordance with a series of commutation states, where a commutation event occurs when a rotor moves from a position associated with one commutation state to a position associated with another commutation state, the method comprising the steps of:
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(a) detecting a commutation event that is asynchronous with an ongoing PWM drive signal of an initial frequency being applied to a motor phase winding; and (b) responsive to detection step (a), at least temporarily increasing the frequency of the ongoing PWM drive signal to a frequency above the initial frequency in order to reach an end of cycle of the ongoing PWM drive signal more quickly than without such a frequency increase; and wherein the initial frequency of the ongoing PWM drive signal is X, in step (b) the frequency of the ongoing PWM drive signal is increased to a frequency Y and, after the end of cycle of the ongoing PWM drive signal at frequency Y, frequency of a next PWM drive signal is decreased to a frequency Z, which is greater than X and less than Y. - View Dependent Claims (7, 8, 9)
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10. A motor control system comprising:
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a motor having multiple phase windings and a movable rotor, the position of the rotor defines multiple commutation states for the phase windings; a sensor arrangement for indicating the occurrence of commutation events when the rotor moves from a position associated with one commutation state to a position associated with another commutation state; and a controller for selectively energizing the phase windings with PWM drive signals, the controller operatively connected with the sensor arrangement and operable, upon occurrence of a commutation event that is asynchronous to an ongoing PWM drive signal of an initial frequency, to increase the frequency of the ongoing PWM drive signal to a frequency above the initial frequency in order to reach an end of cycle for the ongoing PWM drive signal more quickly than without such a frequency increase; and wherein the initial frequency of the ongoing PWM drive signal is X, the increased frequency of the ongoing PWM drive signal is Y, and at the end of cycle of the ongoing PWM drive signal at frequency Y, a next PWM drive signal cycle is initiated at a frequency Z, where Z is between X and Y. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification