Reversible variable-speed 2-phase electric motor

• US 4,774,448 A
• Filed: 12/19/1984
• Issued: 09/27/1988
• Est. Priority Date: 12/20/1983
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Yoshitomi, Kenya
• Primary Examiner(s): Smith, Jr., David
• Application Number:
  US06/683,581
• Time in Patent Office: 1,378 Days
• Field of Search: 318/746-748, 318/811, 318/808
• US Class Current: 318/746
• CPC Class Codes: H02P 21/00 Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
• CPC Class Codes: H02P 23/24 Controlling the direction, e.g. clockwise or counterclockwise

Abstract

A reversible variable-speed two-phase motor is disclosed. The motor comprises two sets of stator coils of equal impedance displaced in space by 90 degrees and transistor inverters to provide exciting current to the stator coils. The current supplied to one of the sets of stator coils is 90 degrees out of phase with the current supplied to the other set of stator coils, and the direction of the current in each set of stator coils reverses every 180 degrees so that a smoothly rotating magnetic field is produced. The motor can be operated as an induction motor or as a synchronous motor or as a direct current brake.

Claims

1. A reversible variable-speed 2-phase motor comprising:

a rotor;

a stator surrounding said rotor;

two sets of stator coils having the same electrical impedance, each set of said stator coils being displaced 90 degrees in space with respect to the other set of stator coils;

converter means for converting 3-phase AC power to DC power;

a control circuit including means for providing a signal indicative of a certain speed, the speed signal providing means including means coupled to a 3-phase AC power for providing a signal indicative of the AC current, a speed setting circuit for providing a signal indicative of a desired motor speed, means for producing an output signal indicative of the difference between the AC current signal and the desired speed signal, and means responsive to the difference signal for converting the difference signal to a signal having a frequency which corresponds to the magnitude of the difference signal, the control circuit further including pulse generating circuitry that provides control signals, the pulse generating circuitry including means responsive to the speed signal for providng first and second output pulses which are 180 degrees out of phase with one another, first and second pulse generating circuits, and means for supplying the first and second output pulses to the first and second pulse generating circuits, wherein the frequency signal is input to the first and second output pulse providing means as the signal indicative of a certain speed and wherein the first and second output pulse providing means include counter means for receiving as a clock signal the signal indicative of a certain speed and providing a reduced frequency signal and flip-flop means for receiving the reduced frequency signal as a clock signal and supplying the first and second output pulses to the first and second pulse generating circuits, respectively;

inverter means associated with each of said sets of stator coils and connected across the outputs of said converter means for providing current to said sets of stator coils in response to the control signals from said control circuit so that the direction of current in each set periodically reverses, said periodic reversal of the direction of current in one of said sets of stator coils being 90 degrees out of phase with the reversal of current provided to said other set of stator coils, wherein the inverter means includes first and second inverters respectively associated with the two sets of stator coils and wherein the first and second pulse generating circuits are respectively associated with the first and second inverters; and

a switch means for reversing the connections between at least one of said inverter means and the associated pulse generating circuit which delivers said control signals to the inverter means in response to a command signal so as to cause said rotor to reverse its rotational direction by shifting the periodic reversal of current in one set of stator coils by 180 electrical degrees.