Brushless permanent magnet motor for use in remote locations

Claim 2

A motor, comprising: a) a three-phase brushless electric motor including first, second, and third stator windings and a permanent magnet rotor; b) an array of commutation transistors electrically connected to the windings; c) three transformers, wherein each transformer includes a primary coil and a secondary coil, and the primary coil of each transformer is electrically coupled across at least one of the windings; d) first, second, and third control circuits, each control circuit being connected to a different transformer to providing timing signals to simulate a Hall effect signal corresponding to the EMFs of that winding, wherein each control circuit includes an integrator to integrate signals received from the corresponding transformer, an offset corrector to remove any direct current voltage from the integrated signal, and a crossover detector to provide an output that changes state in response to the integrated, offset-corrected signal passing through zero; e) first and second mode control circuits for selectively precharging two or more of the control circuits prior to rotation of the rotor; f) first and second offset control circuit for selectively disabling the offset correctors of the precharged control circuits prior to rotation of the rotor; and g) a commutation control circuit, to align the stator and rotor in a predetermined home position in response to preset voltage levels prior to rotation of the motor, and to initiate and sustain rotation of the rotor at a selected time by applying power to gates of the commutation transistors in response to the timing signals from the control circuits.

Claim 3

The motor of claim 1, wherein the windings are arranged in a wye configuration.

Claim 4

The motor of claim 1, wherein the windings are arranged in a delta configuration.

Claim 5

The motor of claim 1, wherein the first and second mode control circuits include electrical relays.

Claim 6

The motor of claim 1, wherein the first and second offset control circuits include electrical relays.

Claim 7

The motor of claim 1, further comprising a mode control circuit to selectively provide the commutation control circuit with preset voltages or signals from the control circuits.

Claim 8

The motor of claim 1, wherein the commutation control circuit comprises a circuit that selects two of the commutation transistors in response to the timing signals and applies electrical power to the gates of the selected transistors for a selected interval.

Claim 9

The motor of claim 1, further comprising three power cables electrically interconnecting the commutation transistors and the windings.

Claim 10

The motor of claim 8, wherein the motor is located downhole in a well and the commutation transistors, transformers, control circuits, and commutation control circuit are positioned above the earth's surface.

Claim 11

The motor of claim 1, further comprising a voltage controller to regulate the magnitude of voltage applied to the windings in response to the speed of the motor's rotation.

Claim 12

The motor of claim 1, further including a current limiting circuit to selectively limit current through the busses prior to rotation of the motor.

Claim 13

The control system of claim 1, wherein each of the offset control circuits is operative to disable the offset corrector of a given control circuit when the timing signal of the given control circuit is in a predetermined state.

Claim 14

The control system of claim 1, wherein the first and second mode control circuits operate to precharge the integrators of the first and second control circuits to a predetermined level.

Claim 15

The control system of claim 1, further including circuitry to regulate the voltage across the busses in response to the speed of rotation of the motor.

Claim 18

The method of claim 15, wherein each control circuit, when not preset, performs steps of: (1) using an integrator to integrate signals received from the stator windings; (2) using an offset corrector to remove direct current offset from the integrated signal; and (3) detecting the zero crossover points of the offset-corrected signal and providing an output that changes state in response to such crossover points.

Claim 19

The method of claim 16, wherein the presetting in step (b) comprises steps of precharging the integrators of two given control circuits and disabling the offset correctors of the given control circuits.

Claim 20

The method of claim 17, wherein the precharging is performed for a predetermined period and then discontinued.

Claim 21

The method of claim 17, comprising a step of re-enabling each disabled offset correctors when the timing signal of the control circuit associated with that disabled offset corrector is in a predetermined state.

Claim 22

The method of claim 15, further comprising steps of regulating the voltage applied to the windings in response to the speed of the motor's rotation.

Claim 23

The method of claim 15, wherein said step (d) of commencing operation of the motor as a brushless D.C. motor comprises providing power to said motor on no more than three cables extending from above ground to downhole in an oil well.

Claim 26

Apparatus for starting a brushless D.C. motor that includes a permanent magnet rotor, a stator, three stator windings, commutation transistors to selectively apply power to the windings to rotate the rotor, and positive and negative busses to supply voltage to the transistors, said apparatus comprising: a) three transformers, each associated with a stator winding to generate an output signal in response signals generated by the associated stator winding; b) commutation control circuitry to selectively gate the transistors in response to a commutation input; c) control circuitry coupled to the transistors and operable in response to the output signals to apply a sequence of voltages on three feedback lines to the commutation input to simulate voltages generated by Hall effect sensors coupled to the rotor during rotation of the motor through a sequence of positions of the rotor relative to the stator; and d) startup circuitry operable prior to rotation of the motor to position the stator and rotor in a first preselected positional relation with respect to each other and to precharge the control circuitry with voltages corresponding to simulated Hall effect voltages generated by Hall effect sensors with the stator and the rotor in a second preselected positional relation while reducing supply voltage available to the commutation transistors from the busses wherein said control circuitry includes integrating circuitry for integrating winding EMF samples to generate simulated Hall effect sensor voltages.

Claim 27

Apparatus for starting a brushless D.C. motor that includes a permanent magnet rotor, a stator, three stator windings, commutation transistors to selectively apply power to the windings to rotate the rotor, and positive and negative busses to supply voltage to the transistors, said apparatus comprising: a) three transformers, each associated with a stator winding to generate an output signal in response signals generated by the associated stator winding; b) commutation control circuitry to selectively gate the transistors in response to a commutation input; c) control circuitry coupled to the transistors and operable in response to the output signals to apply a sequence of voltages on three feedback lines to the commutation input to simulate voltages generated by Hall effect sensors coupled to the rotor during rotation of the motor through a sequence of positions of the rotor relative to the stator; and d) startup circuitry operable prior to rotation of the motor to position the stator and rotor in a first preselected positional relation with respect to each other and to precharge the control circuitry with voltages corresponding to simulated Hall effect voltages generated by Hall effect sensors with the stator and the rotor in a second preselected positional relation while reducing supply voltage available to the commutation transistors from the busses wherein said control circuitry includes integrating circuitry for integrating winding EMF samples to generate simulated Hall effect sensor voltages.

Claim 28

An electric submergible pumping system comprising: a rotary pump having a longitudinal shaft extending therefrom; and a multi-pole brushless electric motor having a stator, stator windings and a permanent magnet rotor, with a first end of the rotor connected to the pump shaft; commutation transistors to selectively apply power to the windings to rotate the rotor, and positive and negative busses to supply voltage to the transistors three transformers, each associated with a stator winding to generate an output signal in response signals generated by the associated stator winding; commutation control circuitry to selectively gate the transistors in response to a commutation input; control circuitry coupled to the transistors and operable in response to the output signals to apply a sequence of voltages on three feedback lines to the commutation input to simulate voltages generated by Hall effect sensors coupled to the rotor during rotation of the motor through a sequence of positions of the rotor relative to the stator; and startup circuitry operable prior to relation of the motor to position the stator and rotor in a first preselected positional relation with respect to each other and to precharge the control circuitry with voltages corresponding to simulated Hall effect voltages generated by Hall effect sensors with the stator and the rotor in a second preselected positional relation while reducing supply voltage available to the commutation transistors from the busses wherein said control circuitry includes integrating circuitry for integrating winding EMF samples to generate simulated Hall effect sensor voltages.

Claim 29

An electric submergible pumping system comprising: a rotary pump having a longitudinal shaft extending therefrom; and a multi-pole brushless electric motor having a stator, stator windings and a permanent magnet rotor, with a first end of the rotor connected to the pump shaft; commutation transistors to selectively apply power to the windings to rotate the rotor, and positive and negative busses to supply voltage to the transistors three transformers, each associated with a stator winding to generate an output signal in response signals generated by the associated stator winding; commutation control circuitry to selectively gate the transistors in response to a commutation input; control circuitry coupled to the transistors and operable in response to the output signals to apply a sequence of voltages on three feedback lines to the commutation input to simulate voltages generated by Hall effect sensors coupled to the rotor during rotation of the motor through a sequence of positions of the rotor relative to the stator; and startup circuitry operable prior to relation of the motor to position the stator and rotor in a first preselected positional relation with respect to each other and to precharge the control circuitry with voltages corresponding to simulated Hall effect voltages generated by Hall effect sensors with the stator and the rotor in a second preselected positional relation while reducing supply voltage available to the commutation transistors from the busses wherein said control circuitry includes integrating circuitry for integrating winding EMF samples to generate simulated Hall effect sensor voltages.

Claim 30

An electric submergible pumping system of claim 24 wherein the rotary pump further comprises a multiple stage centrifugal pump.

Claim 31

An electric submergible pumping system of claim 24 wherein the rotary pump further comprises a progressive cavity pump.

Claim 32

An electric submergible pumping system of claim 24 wherein the electric motor further comprises a three-phase D.C. brushless electric motor.

Claim 33

A multi-pole brushless permanent magnet motor system for use with an electrical submergible pumping system, comprising: an elongated housing; stator windings disposed within the housing; a permanent magnet rotor disposed for rotary movement within a longitudinal opening formed within the stator windings; and a first end of the rotor adapted for interconnection with a rotary pump; commutation transistors to selectively apply power to the windings to rotate the rotor, and positive and negative busses to supply voltage to the transistors three transformers, each associated with a stator winding to generate an output signal in response signals generated by the associated stator winding; commutation control circuitry to selectively gate the transistors in response to a commutation input; control circuitry coupled to the transistors and operable in response to the output signals to apply a sequence of voltages on three feedback lines to the commutation input to simulate voltages generated by Hall effect sensors coupled to the rotor during rotation of the motor through a sequence of positions of the rotor relative to the stator; and startup circuitry operable prior to rotation of the motor to position the stator and rotor in a first preselected positional relation with respect to each other and to precharge the control circuitry with voltages corresponding to simulated Hall effect voltages generated by Hall effect sensors with the stator and the rotor in a second preselected positional relation while reducing supply voltage available to the commutation transistors from the busses wherein said control circuitry includes integrating circuitry for integrating winding EMF samples to generate simulated Hall effect sensor voltages.

Claim 34

A multi-pole brushless permanent magnet motor system for use with an electrical submergible pumping system, comprising: an elongated housing; stator windings disposed within the housing; a permanent magnet rotor disposed for rotary movement within a longitudinal opening formed within the stator windings; and a first end of the rotor adapted for interconnection with a rotary pump; commutation transistors to selectively apply power to the windings to rotate the rotor, and positive and negative busses to supply voltage to the transistors three transformers, each associated with a stator winding to generate an output signal in response signals generated by the associated stator winding; commutation control circuitry to selectively gate the transistors in response to a commutation input; control circuitry coupled to the transistors and operable in response to the output signals to apply a sequence of voltages on three feedback lines to the commutation input to simulate voltages generated by Hall effect sensors coupled to the rotor during rotation of the motor through a sequence of positions of the rotor relative to the stator; and startup circuitry operable prior to rotation of the motor to position the stator and rotor in a first preselected positional relation with respect to each other and to precharge the control circuitry with voltages corresponding to simulated Hall effect voltages generated by Hall effect sensors with the stator and the rotor in a second preselected positional relation while reducing supply voltage available to the commutation transistors from the busses wherein said control circuitry includes integrating circuitry for integrating winding EMF samples to generate simulated Hall effect sensor voltages.