Brushless permanent magnet motor for use in remote locations

A method for controlling a brushless D.C. motor having a stator, first, second, and third stator windings, an array of commutating transistors coupled to said stator windings, said array operable under control of at least three commutation control circuits, to provide power from a pair of busses to said windings, and a permanent magnet rotor, said method comprising steps of:

• a) providing a first level of voltage across said pair of busses;
• b) providing preset voltages to said commutation control circuits to gate selected commutating transistors in said array to align the stator and rotor in a predetermined home position;
• c) presetting outputs of at least two of said at least three control circuits, each control circuit being coupled to a different winding and operative when not preset to provide timing signals corresponding to a simulated Hall effect signal corresponding to the EMF of that winding;
• and
• d) commencing operation of the motor as a brushless D.C. motor by increasing said voltage across said pair of busses from said first level to a second level, removing the preset voltages from the commutating control circuit, and instead providing the commutating control circuit with outputs from the three control circuits
• wherein said step (c) further comprises the step of obtaining a sample of EMF of at least one of said windings and integrating said sample to generate said simulated Hall effect signal.

A method of controlling the rotation of a three phase brushless electric motor having first, second, and third stator windings, an array of commutating transistors coupled to said stator windings, said array operable under control of at least three commutation control circuits to provide power from a pair of busses to said windings, and a permanent magnet rotor, said method comprising:

• (a) in a startup mode, performing steps comprising:
• 1) providing a first level of voltage across said pair of busses;
• 2) providing preset voltages to said commutation control circuits to gate selected commutating transistors to align the stator and rotor in a predetermined home position;
• 3) presetting outputs of at least two of three control circuits, each control circuit being coupled to a different winding and operative when not preset to provide timing signals to simulate a Hall effect signal corresponding to the EMF of that winding, wherein the preset outputs correspond to a positional relationship between the stator and rotor immediately after rotation from the home position;
• wherein said step (3) further comprises obtaining a sample of EMF of at least one of said windings and integrating said sample to generate said simulated Hall effect signal;
• and
• (b) in a brushless D.C. mode, performing steps comprising:
• 1) sampling the EMF of each winding;
• 2) producing a three-phase output being conducted on three feedback lines to simulate Hall effect signals corresponding to the sampled EMFs;
• 3) gating selected commutation transistors in response to the three-phase output;
• and
• 4) discontinuing provision of the preset voltages to the commutation control circuit and instead providing the commutating control circuit with the three-phase output.

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.

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.

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.