Granted Patent B2

US 7,081,725 · App. 10/772,399 · Granted Jul 25, 2006

Abstract

Claims (16)

1. A power drive electronics apparatus operably connected between a frequency variable generator and an electric motor, comprising: a three-phase diode rectifier having a three-phase AC input, a positive DC output terminal and a negative DC output terminal, said three-phase AC input operably connected to said electric motor and said positive DC output terminal operably connected to said frequency variable generator's rotor windings; a diode having an anode and a cathode, said cathode operably connected to said positive DC output terminal of said three-phase diode rectifier; a battery operably connected to said anode of said diode; and a capacitor operably connected between said positive DC output terminal and said negative DC output terminal of said three-phase diode rectifier.

2. The power drive electronics apparatus according to claim 1 further comprising a switch having a first terminal and a second terminal, wherein said first terminal of said switch is operably connected to said battery and a second terminal of said switch is operably connected to said anode of said diode.

3. The power drive electronics apparatus according to claim 2 wherein said power electronics apparatus further comprises: at least one high side switch having a first terminal operably connected to said positive DC output terminal of said three-phase diode rectifier, a second terminal operably connected to said frequency variable generators rotor winding, and a control terminal; and a controller operably connected to said control terminal of said at least one high side switch.

4. The power drive electronics apparatus according to claim 2 wherein said power electronics apparatus further comprises: an inverter having a three-phase ac output, a positive DC input terminal and a negative DC input terminal, wherein said positive DC input terminal is operably connected to said positive DC output terminal of said three-phase diode rectifier, said negative DC input terminal is operably connected to said negative DC output terminal of said three-phase diode rectifier, and said three-phase ac output is operably connected to said frequency variable generator's rotor winding; and a controller operably connected to said inverter.

5. The power drive electronics apparatus according to claim 4 wherein said inverter includes three phase legs operably connected in parallel, each phase leg includes two switches operably connected in series; and said controller includes a microprocessor, memory operably connected to said microprocessor, and software stored in said memory, said software includes instructions to turn said switches of said inverter on and off, whereby said inverter outputs a pulse width modulated electric current, said instructions include the following steps: reading motor speed, generator speed and desired torque; calculating a desired generator rotor current; reading said desired generator rotor current, a DC bus voltage, and a three-phase generator rotor current; calculating a desired instantaneous generator three-phase rotor current; calculating a proportional and integration gain; comparing said desired instantaneous three-phase generator rotor current with said three-phase generator rotor current; producing a phase current error; processing said phase current error; calculating three-phase pulse width modulation duty cycles; and outputting said three-phase pulse width modulation duty cycles.

6. The power drive electronics apparatus according to claim 4 further comprising an energy absorber operably connected between said positive DC output terminal and said negative DC output terminal of said three-phase diode rectifier.

7. The power drive electronics apparatus according to claim 4 wherein said frequency variable generator is a double-fed induction generator and said electric motor is an induction motor.

8. A method of controlling a power drive electronics apparatus operably connected between a frequency variable generator and an electric motor, said power drive electronics apparatus comprising: a three-phase diode rectifier having a three-phase AC input, a positive DC output terminal and a negative DC output terminal, said three-phase AC input operably connected to said electric motor and said positive DC output terminal operably connected to said frequency variable generator's rotor windings; a diode having an anode ends cathode, said cathode operably connected to said positive DC output terminal of said three-phase diode rectifier; a battery operably connected to said anode of said diode; and a capacitor operably connected between said positive DC output terminal and said negative DC output terminal of said three-phase diode rectifier, the method comprising:

applying system power to the rotor windings of the generator;

disconnecting said system power; rectifying ac power from a motor;

pulse width modulating said rectified ac power; and

applying said pulse width modulated rectified ac power to the rotor winding of the generator.

9. The method according to claim 8 further comprising the steps of: pulse width modulating said rectified ac power, and applying said pulse width modulated rectified ac power to the rotor winding of the generator.

10. The method according to claim 9 further comprising the step of absorbing energy from said motor during deceleration.

11. The method according to claim 9 wherein said step of pulse width modulating said rectified ac power comprises: reading motor speed, generator speed and desired torque; calculating a desired generator rotor current; reading said desired generator rotor current, a DC bus voltage, and a three-phase generator rotor current; calculating a desired instantaneous generator tree-phase rotor current; calculating a proportional and integration gain; comparing said desired instantaneous three-phase generator rotor current with said three-phase generator rotor current; producing a phase current error; processing said phase current error; calculating three-phase pulse width modulation duty cycles; and outputting said three-phase pulse width modulation duty cycles.

12. The method according to claim 11 further comprising the step of absorbing energy from said motor during deceleration.

Assignments (6)