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Multilevel DC link inverter

  • US 6,577,087 B2
  • Filed: 05/10/2001
  • Issued: 06/10/2003
  • Est. Priority Date: 05/10/2001
  • Status: Expired due to Fees
First Claim
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1. A circuit for controlling a three-phase machine having a stator with stator windings and a rotor, the circuit comprising:

  • a plurality of commutation switches which are connected to supply current to the stator windings;

    a plurality of dc source connections for receiving a plurality of incremental dc voltages and for applying a selected sum of said incremental dc voltages to said plurality of commutation switches to provide a base dc voltage, while controlling one of the incremental dc voltages to provide a varying pulsed signal to said commutation switches relative to said base dc voltage;

    at least one sensor for sensing a parameter of the motor from which a speed and rotor position of the motor can be determined; and

    a controller responsive to said sensor for determining the speed and rotor position of the motor, said controller being connected for control of said dc source connections to change base dc voltage in response to changes in speed of the motor without increasing current ripple in the stator windings substantially above a current ripple resulting from applying the varying pulsed signal derived from one of the incremental dc voltages to said commutation switches, said controller being connected also for control of said commutation switches to sequentially excite the stator windings of said motor.

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