Adaptable high efficiency power inverter system

Patent metadata

Field	Value
Publication number	US-10218277-B2
Application number	US-201615050054-A
Country	US
Kind code	B2
Filing date	Feb 22, 2016
Priority date	Feb 22, 2016
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

Increased DC-to-AC power conversion efficiency in a scalable, flexible, resilient, cascading inverter driver topology. Plural power cells, which include a rectifier and an inverter, are arranged in a series/parallel topology. Use of plural power cells increases efficiency by reducing voltage transition losses and by increasing duty cycle. Also, the power cells output AC to an electric motor using a forward-looking controller that responds to varying power demand while maintaining motor speed at a maximum efficiency level. Power output is varied by varying the width of rectifier output pulses to the inverters while maintaining pulse voltage. Transitions between power levels are smoothed by pulse density modulation. Pulse density, determined automatically in the inverter, begins high and gradually becomes less dense so voltage changes rapidly then slowing gradually. The topology and power cell components allow faulty power cells 10 to be isolated and bypassed.

First claim

What is claimed is:

1. An electric power inverter system, comprising:
a controller; and
a plurality of power cells, each including
a rectifier configured to receive electricity and output a direct current (DC) voltage, and
an inverter comprising four switches in an H-bridge configuration, said inverter receiving said direct current voltage from said rectifier and generating an alternating current (AC) voltage, and wherein said controller enables said power cell to operate in an ON state wherein said alternating current voltage of said power cell is maximum, an OFF state wherein said alternating current voltage of said power cell is zero, and a high efficiency state wherein said alternating current voltage is between said ON state and said OFF state;
wherein said controller is configured to monitor a load, and in response to changes in the load, to control each power cell's state so as to effectively operate with more or fewer power cells enabled.

2. The electric power inverter system of claim 1 , wherein, when said output of said power cell varies between said power level of said ON state and power level of said OFF state, said controller determines the rate at which said output of said power cell varies.

3. The electric power inverter system of claim 1 wherein the controller operates the electric power inverter system at high efficiency by, for each required output voltage, operating a subset of the power cells in the ON state, optionally operating one power cell in the high efficiency state, and operating the remaining power cells in the OFF state.

4. The electric power inverter system of claim 1 wherein, for each power cell, the controller controls the DC output of the rectifier by pulse width modulation, which determines the AC output voltage of the inverter.

5. The electric power inverter system of claim 1 wherein, for each power cell, the controller controls the AC output of the inverter by pulse density modulation, which smooths transitions between discrete voltage output values.

6. An electric power inverter system, comprising:
a controller;
an electric motor; and
a plurality of power cells controlled by said controller and providing power to said electric motor, each power cell of said plurality of power cells including
a rectifier configured to rectify electricity and output a direct current (DC) voltage, and
an inverter comprising four switches in an H-bridge configuration, said inverter receiving said direct current voltage from said rectifier and producing as output an alternating current (AC) voltage to said electric motor, and wherein a power cell of said plurality of power cells has at least three states, including an ON state wherein said alternating current voltage of said power cell is maximized, and an OFF state wherein said alternating current voltage of said power cell is zero, and a high efficiency state wherein said alternating current voltage is between said ON state and said OFF state;

wherein said controller is configured to control a speed of the electric motor by controlling each power cell's state so as to effectively operate with more or fewer power cells enabled, thus controlling the voltage and current output by the power cells to the electric motor.

7. The electrical power inverter system of claim 6 , wherein said motor has a peak efficiency dependinq on its speed, and wherein said controller operates said motor at said speed.

8. The electric power inverter system of claim 6 , wherein said power cell has a variable state, and wherein said alternating current voltage of said power cell transitions between said output of said power cell in said ON state and said output of said power cell in OFF state.

9. The electric power inverter system of claim 8 , wherein said power cell transitions in pulses when in said variable state.

10. The electric power inverter system of claim 9 , wherein said controller provides a number of said pulses and wherein said number of said pulses is related to the magnitude of a transition in voltage between said ON state and said OFF state.

11. The electric power inverter system of claim 9 , wherein said pulses have a pulse density and wherein said pulse density varies to control the speed of the transition between ON and OFF.

12. The electric power inverter system of claim 11 , wherein said direct current voltage from said rectifier is pulsed.

13. The electric power inverter system of claim 12 , wherein said controller is configured to set the duration of said pulses.

14. The electric power inverter system of claim 12 , wherein said pulses vary in duration and have constant magnitude.

15. The electric power inverter system of claim 6 , wherein said plural power cells are arranged in series.

16. The electric power inverter system of claim 6 , wherein said plural power cells are arranged in parallel.

17. The electric power inverter system of claim 6 , wherein said plural power cells are arranged in a topology including power cells in series and series-connected strings of power cells in parallel.

18. The electric power inverter system of claim 6 , wherein said power cell includes a bypass switch responsive to said controller, and wherein said controller bypasses said power cell using said bypass switch in the event said power cell fails.

19. The electric power inverter system of claim 18 , wherein said bypass switch is temperature sensitive and operates to bypass said power cell if said power cell overheats.

20. The electric power inverter system of claim 6 , wherein said output of said power cell is added to power outputs of other power cells of said plurality of power cells in a cascade.

21. The electric power inverter system of claim 6 , wherein said power cell further comprises a fuse.

22. The electric power inverter system of claim 6 , further comprising an input switch for said inverter to isolate said inverter in said power cell.

23. The electric power inverter system of claim 6 , further comprising a capacitor between said rectifier and said inverter.

24. The electric power inverter system of claim 6 , wherein said controller is configured to monitor peak voltage, load current, power, and temperature by sampling at a sampling frequency.

25. The electric power inverter system of claim 6 wherein the controller operates the electric power inverter system at high efficiency by, for each required output voltage, operating a subset of the power cells in the ON state, optionally operating one power cell in the high efficiency state, and operating the remaining power cells in the OFF state.

26. The electric power inverter system of claim 6 wherein, for each power cell, the controller controls the DC output of the rectifier by pulse width modulation, which determines the AC output voltage of the inverter.

27. The electric power inverter system of claim 6 wherein, for each power cell, the controller controls the AC output of the inverter by pulse density modulation, which smooths transitions between discrete voltage output values.

28. The electric power inverter system of claim 6 wherein the controller sets the input and output voltages of each power cell so as to generate a desired AC output voltage level, with a predetermined difference in input and output voltage for each power cell determined to maximize efficiency of the power cells.

Assignees

• Boeing Co

Inventors

• Carralero Michael A
• Quiambao Jimmy M
• Peck James L

Classifications

• H02M3/285

  Single converters with a plurality of output stages connected in parallel (parallel operation of a plurality of converters in DC distribution networks H02J1/10) · CPC title

• H02P27/06

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• H02M7/53871

  with automatic control of output voltage or current · CPC title

• H02M2001/007

  Electricity · mapped topic

• H02M2001/0077

  Electricity · mapped topic