Reduced noise controller for a switched reluctance machine using active noise cancellation

Claim 2

A switched reluctance machine system including a stator, a phase winding positioned within the stator, and a rotor adapted to rotate with respect to the stator, the rotor defining various angular positions as it rotates with respect to the stator, the system comprising: a rotor position detector for detecting the angular position of the rotor and providing rotor position signals representative of the angular position of the rotor; an electronic controller responsive to the rotor position signals for producing an output for energizing the phase winding over at least one angular period of rotor rotation, the angular period of rotation having a termination point corresponding to a predefined angular position of the rotor; and an auxiliary control circuit responsive to the output of the electronic controller for applying at least one timed voltage pulse to the phase winding, wherein the at least one timed voltage pulse begins at a predetermined point in time after the termination of the at least one angular period, and wherein the at least one voltage pulse produces forces in the reluctance motor system that actively cancel unwanted vibrations.

Claim 3

A controller for a switched reluctance machine that includes a phase winding, at least one switch coupled to the phase winding, and a controller that provides firing signals to the switch, wherein the firing signals actuate the switch to energize the phase winding, the controller comprising: an auxiliary pulse control circuit that monitors the firing signals and, upon detection of a switch-off point corresponding to an opening of at least one switch, generates an auxiliary firing pulse, wherein the auxiliary firing pulse begins after a first predetermined period of time has passed since the detection of the switch-off point and terminates after a second predetermined period of time has passed since the detection of the switch-off point.

Claim 4

A controller for a switched reluctance machine that includes a phase winding, at least one switch coupled to the phase winding, and a controller that provides firing signals to the switch, wherein the firing signals actuate the switch to energize the phase winding, the controller comprising: an auxiliary pulse control circuit that monitors the firing signals and, upon detection of a switch-off point corresponding to an opening of at least one switch, generates an auxiliary firing pulse, wherein the auxiliary firing pulse begins after a first predetermined period of time has passed since the detection of the switch-off point and terminates after a second predetermined period of time has passed since the detection of the switch-off point.

Claim 5

An auxiliary pulse control circuit for monitoring the energization of a phase winding in a switched reluctance machine having a stator and for detecting the occurrence of a predefined switching event associated with the energization of the phase winding and applying at least one voltage pulse to the phase winding at a predetermined point in time following the occurrence of the predefined switching event to reduce unwanted vibrations, the auxiliary pulse control circuit comprising: a decoder circuit for monitoring the energization of the phase winding and generating a pulsed output signal when the predefined switching event occurs; a first edge-triggered monostable responsive to the pulsed output signal for generating a first voltage pulse signal of a first predetermined time duration, the first voltage pulse signal having a termination at the end of the first predetermined time duration; a second edge-triggered monostable responsive to the termination of the first voltage pulse signal for generating a second voltage pulse signal of a second predetermined time duration; a switch coupled to receive the output of the second edge-triggered monostable, the switch coupling the phase winding to a source of electric power in response to the second voltage pulse signal; wherein the first and second time durations are selected such that the coupling of the phase winding to the source of electric power in response to the second pulse signal produces vibration forces in the stator that substantially cancel unwanted vibrations.

Claim 6

An auxiliary pulse control circuit for monitoring the energization of a phase winding in a switched reluctance machine having a stator and for detecting the occurrence of a predefined switching event associated with the energization of the phase winding and applying at least one voltage pulse to the phase winding at a predetermined point in time following the occurrence of the predefined switching event to reduce unwanted vibrations, the auxiliary pulse control circuit comprising: a decoder circuit for monitoring the energization of the phase winding and generating a pulsed output signal when the predefined switching event occurs; a first edge-triggered monostable responsive to the pulsed output signal for generating a first voltage pulse signal of a first predetermined time duration, the first voltage pulse signal having a termination at the end of the first predetermined time duration; a second edge-triggered monostable responsive to the termination of the first voltage pulse signal for generating a second voltage pulse signal of a second predetermined time duration; a switch coupled to receive the output of the second edge-triggered monostable, the switch coupling the phase winding to a source of electric power in response to the second voltage pulse signal; wherein the first and second time durations are selected such that the coupling of the phase winding to the source of electric power in response to the second pulse signal produces vibration forces in the stator that substantially cancel unwanted vibrations.

Claim 7

The auxiliary pulse control circuit of claim 3 wherein the predefined switching event comprises the reversal of the phase winding on the rails of a DC bus.

Claim 8

The auxiliary pulse control circuit of claim 3 wherein the phase winding of the switched reluctance machine is coupled to a DC voltage source by at least one switching device, wherein the switching device is responsive the to firing signals, and wherein the decoder circuit produces the pulsed output signal in response to a change in state of the firing signals applied to the switching device.

Claim 9

A controller for a switched reluctance machine system, the system including a switched reluctance machine having a rotor, and a stator, the stator having at least one phase winding energizable in response to firing signals, the controller comprising: a decoder circuit for monitoring the firing signals and for generating a pulse output signal when the firing signals indicate that a predefined switching event has occurred; a counter having a reset terminal coupled to the output of the decoder circuit, and a clock terminal coupled to a substantially fixed frequency clock, wherein the counter provides an output that is incremented according to the fixed frequency clock and wherein the output of the counter is reset in response to a pulse output signal from the decoder circuit; a comparison circuit coupled to the output of the counter for comparing the output of the counter to a first preselected value and a second preselected value, the comparison providing an output signal that is at a first logic level when the counter output is between the first and the second values and at a second logic level otherwise; and a switch coupled to the output of the comparison circuit, wherein the switch couples the phase winding to a source of electric power when the output of the comparator is at the first logic level; wherein the first and the second values are selected such that the coupling of the phase winding to the source of electric power produces vibrational forces in the machine that substantially cancel unwanted vibrations.

Claim 10

A controller for a switched reluctance machine system, the system including a switched reluctance machine having a rotor, and a stator, the stator having at least one phase winding energizable in response to firing signals, the controller comprising: a decoder circuit for monitoring the firing signals and for generating a pulse output signal when the firing signals indicate that a predefined switching event has occurred; a counter having a reset terminal coupled to the output of the decoder circuit, and a clock terminal coupled to a substantially fixed frequency clock, wherein the counter provides an output that is incremented according to the fixed frequency clock and wherein the output of the counter is reset in response to a pulse output signal from the decoder circuit; a comparison circuit coupled to the output of the counter for comparing the output of the counter to a first preselected value and a second preselected value, the comparison providing an output signal that is at a first logic level when the counter output is between the first and the second values and at a second logic level otherwise; and a switch coupled to the output of the comparison circuit, wherein the switch couples the phase winding to a source of electric power when the output of the comparator is at the first logic level; wherein the first and the second values are selected such that the coupling of the phase winding to the source of electric power produces vibrational forces in the machine that substantially cancel unwanted vibrations.

Claim 11

A switched reluctance machine system comprising: a switched reluctance machine having a stator, at least one phase winding associated with the stator, and a rotor rotatably positioned with respect to the stator, wherein energization of the phase winding produces a desired machine output; an electronic controller coupled to the phase winding and to a source of electric power, the electronic controller energizing the phase winding in response to the angular position of the rotor by coupling the phase winding to the source of electric power when the rotor reaches a first angular position and de-coupling the phase winding from the source of electric power when the rotor reaches a second angular position; and auxiliary pulse circuitry coupled to the phase winding and the electronic controller for applying a plurality of voltage pulses to the phase winding, the plurality of voltage pulses beginning at a predetermined point in time following the de-coupling of the phase winding from the source of electric power, wherein the application of the auxiliary voltage pulses to the phase winding produces vibrational forces in the machine that substantially cancel unwanted vibrations.

Claim 12

A switched reluctance machine system comprising: a switched reluctance machine having a stator, at least one phase winding associated with the stator, and a rotor rotatably positioned with respect to the stator, wherein energization of the phase winding produces a desired machine output; an electronic controller coupled to the phase winding and to a source of electric power, the electronic controller energizing the phase winding in response to the angular position of the rotor by coupling the phase winding to the source of electric power when the rotor reaches a first angular position and de-coupling the phase winding from the source of electric power when the rotor reaches a second angular position; and auxiliary pulse circuitry coupled to the phase winding and the electronic controller for applying a plurality of voltage pulses to the phase winding, the plurality of voltage pulses beginning at a predetermined point in time following the de-coupling of the phase winding from the source of electric power, wherein the application of the auxiliary voltage pulses to the phase winding produces vibrational forces in the machine that substantially cancel unwanted vibrations.

Claim 13

The system of claim 7 wherein the electronic controller includes circuitry for chopping the current in the phase winding when the rotor is in an angular position between the first angular position and the second angular position.

Claim 16

The method of claim 9 further comprising the step of chopping the current in the phase winding when the rotor is between the first angular position and the second angular position.

Claim 17

The method of claim 9 further comprising the step of applying a second voltage pulse of a second predetermined time duration to the phase winding at a second predetermined point in time following the switch-off point, wherein the application of the second voltage pulse produces additional vibrational forces in the machine system that reduce additional unwanted vibrations.

Claim 22

The method of claim 13 where the step of detecting the predefined switching event comprises the step of detecting when the phase winding is de-coupled from a DC voltage source.

Claim 23

A control system for a switched reluctance machine comprising a rotor, a stator and at least one phase winding, the system comprising: switch means connectable with the phase winding and actuatable to energize the phase winding; and control means operable to produce firing signals to change the conduction of the switch means from one state to another state to reverse the voltage across the phase winding and thereafter to produce at least one auxiliary firing pulse to change the conduction of the switched means from the other state to the one state for the duration of the at least one auxiliary firing pulse, which pulse is timed to cancel distortions of the stator resulting from the voltage reversal across the phase winding.

Claim 24

A control system for a switched reluctance machine comprising a rotor, a stator and at least one phase winding, the system comprising: switch means connectable with the phase winding and actuatable to energize the phase winding; and control means operable to produce firing signals to change the conduction of the switch means from one state to another state to reverse the voltage across the phase winding and thereafter to produce at least one auxiliary firing pulse to change the conduction of the switched means from the other state to the one state for the duration of the at least one auxiliary firing pulse, which pulse is timed to cancel distortions of the stator resulting from the voltage reversal across the phase winding.

Claim 25

A system as claimed in claim 15 in which the first auxiliary firing pulse is timed to coincide with the first zero-crossing of an oscillatory distortion of the stator.

Claim 26

A control system for a switched reluctance machine comprising a rotor, a stator and at least one phase winding, the system comprising: switch means connectable with the phase winding and actuatable to energize the phase winding; and control means operable to produce firing signals to change the conduction of the switch means from one state to another state to reverse the voltage across the phase winding and thereafter to produce at least one auxiliary firing pulse to change the conduction of the switched means from the other state to the one state for the duration of the at least one auxiliary firing pulse, which pulse is timed to cancel distortions of the stator resulting from the voltage reversal across the phase winding wherein the control means include an auxiliary pulse control circuit operable to monitor the firing signals and, in response to the detection of a switch-off point corresponding to an opening of at least part of the switch means, to generate the first auxiliary firing pulse, and wherein the auxiliary firing pulse begins after a first predetermined period following detection of the switch-off point and terminates after a second predetermined period following detection of the switch-off point.

Claim 27

A control system for a switched reluctance machine comprising a rotor, a stator and at least one phase winding, the system comprising: switch means connectable with the phase winding and actuatable to energize the phase winding; and control means operable to produce firing signals to change the conduction of the switch means from one state to another state to reverse the voltage across the phase winding and thereafter to produce at least one auxiliary firing pulse to change the conduction of the switched means from the other state to the one state for the duration of the at least one auxiliary firing pulse, which pulse is timed to cancel distortions of the stator resulting from the voltage reversal across the phase winding wherein the control means include an auxiliary pulse control circuit operable to monitor the firing signals and, in response to the detection of a switch-off point corresponding to an opening of at least part of the switch means, to generate the first auxiliary firing pulse, and wherein the auxiliary firing pulse begins after a first predetermined period following detection of the switch-off point and terminates after a second predetermined period following detection of the switch-off point.

Claim 28

A control system for a switched reluctance machine comprising a rotor, a stator and at least one phase winding, the system comprising: switch means connectable with the phase winding and actuatable to energize the phase winding; and control means operable to produce firing signals to change the conduction of the switch means from one state to another state to reverse the voltage across the phase winding and thereafter to produce at least one auxiliary firing pulse to change the conduction of the switched means from the other state to the one state for the duration of the at least one auxiliary firing pulse, which pulse is timed to cancel distortions of the stator resulting from the voltage reversal across the phase winding wherein the control means comprise a decoder circuit for monitoring the energization of the phase winding and generating a pulsed output signal when the change of the conduction of the switch means from the one state to the other state has occurred, a first edge-triggered monostable responsive to the pulsed output signal for generating a first voltage pulse signal of a first duration, a second edge-triggered monostable responsive to termination of the first voltage pulse signal for generating a second voltage pulse signal of a second duration, the switch means being arranged to receive the output of the second edge-triggered monostable as the auxiliary firing pulse to couple the phase winding to a source of electric power in response thereto.

Claim 29

A control system for a switched reluctance machine comprising a rotor, a stator and at least one phase winding, the system comprising: switch means connectable with the phase winding and actuatable to energize the phase winding; and control means operable to produce firing signals to change the conduction of the switch means from one state to another state to reverse the voltage across the phase winding and thereafter to produce at least one auxiliary firing pulse to change the conduction of the switched means from the other state to the one state for the duration of the at least one auxiliary firing pulse, which pulse is timed to cancel distortions of the stator resulting from the voltage reversal across the phase winding wherein the control means comprise a decoder circuit for monitoring the energization of the phase winding and generating a pulsed output signal when the change of the conduction of the switch means from the one state to the other state has occurred, a first edge-triggered monostable responsive to the pulsed output signal for generating a first voltage pulse signal of a first duration, a second edge-triggered monostable responsive to termination of the first voltage pulse signal for generating a second voltage pulse signal of a second duration, the switch means being arranged to receive the output of the second edge-triggered monostable as the auxiliary firing pulse to couple the phase winding to a source of electric power in response thereto.

Claim 30

A control system for a switched reluctance machine comprising a rotor, a stator and at least one phase winding, the system comprising: switch means connectable with the phase winding and actuatable to energize the phase winding; and control means operable to produce firing signals to change the conduction of the switch means from one state to another state to reverse the voltage across the phase winding and thereafter to produce at least one auxiliary firing pulse to change the conduction of the switched means from the other state to the one state for the duration of the at least one auxiliary firing pulse, which pulse is timed to cancel distortions of the stator resulting from the voltage reversal across the phase winding wherein the control means comprise a decoder circuit for monitoring the firing signals and for generating the auxiliary firing pulse when the firing signals have occurred, a counter having a reset terminal coupled to the output of the decoder circuit, and a clock terminal coupled to a substantially fixed frequency clock, wherein the counter provides an output that is incremented according to the fixed frequency clock and wherein the output of the counter is reset in response to a pulse output signal from the decoder circuit and a comparator coupled to the output of the counter for comparing the output of the counter with a first pre-selected value and a second pre-selected value, the comparator providing the auxiliary firing pulse when the counter output is between the first and second pre-selected values, the switch means being operatively coupled to the output of the comparator, wherein the switch means couple the phase winding to a source of electric power when the output of the comparator produces the auxiliary firing pulse.

Claim 31

A control system for a switched reluctance machine comprising a rotor, a stator and at least one phase winding, the system comprising: switch means connectable with the phase winding and actuatable to energize the phase winding; and control means operable to produce firing signals to change the conduction of the switch means from one state to another state to reverse the voltage across the phase winding and thereafter to produce at least one auxiliary firing pulse to change the conduction of the switched means from the other state to the one state for the duration of the at least one auxiliary firing pulse, which pulse is timed to cancel distortions of the stator resulting from the voltage reversal across the phase winding wherein the control means comprise a decoder circuit for monitoring the firing signals and for generating the auxiliary firing pulse when the firing signals have occurred, a counter having a reset terminal coupled to the output of the decoder circuit, and a clock terminal coupled to a substantially fixed frequency clock, wherein the counter provides an output that is incremented according to the fixed frequency clock and wherein the output of the counter is reset in response to a pulse output signal from the decoder circuit and a comparator coupled to the output of the counter for comparing the output of the counter with a first pre-selected value and a second pre-selected value, the comparator providing the auxiliary firing pulse when the counter output is between the first and second pre-selected values, the switch means being operatively coupled to the output of the comparator, wherein the switch means couple the phase winding to a source of electric power when the output of the comparator produces the auxiliary firing pulse.