Rectifier and System for Controlling the Speed of an Electric Motor

• US 20070296363A1
• Filed: 07/05/2005
• Published: 12/27/2007
• Est. Priority Date: 07/05/2004
• Status: Active Grant

• Current Assignee: Moteurs Leroy Somer (Emerson Electric Company)
• Original Assignee: Moteurs Leroy Somer (Emerson Electric Company)
• Inventors: Andrejak, Jean-Marie, Andrieux, Christian, Tientcheu-Yamdeu, Mathias, Lagarde, Alexandre
• Granted Patent: US 7,737,647 B2
• Time in Patent Office: Days
• US Class Current: 318/504
• CPC Class Codes: H02M 5/4585 having a rectifier with controlled elements
• CPC Class Codes: H02M 7/797 using semiconductor devices only
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence

Abstract

The invention concerns a reversible current rectifier, for connection to part of a polyphase network and to a continuous bus comprising a plurality of rectifier cells each rectifier cell including a rectifying device and a on-way electronic switch connected in anti-parallel with the rectifier device, the rectifying devices of different cells being arranged so as to form one rectifier. Each rectifier cell comprises means for controlling the electronic switch of the cell arranged to control the latter in closure after detecting a conduction of the rectifying device of the cell so as to enable current to be returned to the network. The control means are arranged to receive a signal external to the cell, for controlling the opening of the electronic switch, derived from another rectifier cell.

Claims

1. A system for controlling the speed of an electric motor comprising:

a converter to be connected to a polyphase electricity network and to a DC bus

a filtering stage for the DC bus comprising at least one capacitor,

a power stage,

a control unit of the power stage,

the converter being reversible and arranged to return to the network at least a fraction of the energy likely to be restored by the electric motor in operation.

2. The system as claimed in claim 1, wherein the filtering stage has an insufficient capacitance to stabilize the operation of the motor.

3. The control system as claimed in claim 1, wherein the control system has no chopper and no braking resistor.

4. The control system as claimed in claim 1, wherein the control unit of the power stage and the power stage are configured to power an asynchronous or synchronous motor.

5. The control system as claimed in claim 1, wherein the control unit for the power stage and the power stage are arranged to power a three-phase motor.

6. The control system as claimed in claim 1, wherein the power stage is configured to drive a motor with a power greater than or equal to 1 kW.

7. The control system as claimed in claim 1, wherein the converter comprises self-switched switching cells.

8. The control system as claimed in claim 1, wherein the capacitance of the at least one capacitor of the filtering stage is less than or equal to 5 μ

F per kW of power supplied.

9. The control system as claimed in claim 1, wherein the motor is powered by a current having a frequency greater than 300 Hz.

10. A reversible current rectifier, to be connected to a polyphase network and to a DC bus comprising:

a plurality of rectifier cells each rectifier cell comprising a rectifier device and a one-way electronic switch connected in anti-parallel with the rectifier device, the rectifier devices of the various cells being arranged so as to form one rectifier,

each rectifier cell comprising means of controlling the electronic switch of the cell arranged to close the latter after detecting a conduction of the rectifier device of the cell, so as to enable current to be returned to the network, rectifier in which the control means are arranged to receive a signal external to the cell, controlling the opening of the electronic switch, from another rectifier cell.

11. The rectifier of claim 10, wherein the rectifier is a full-wave rectifier.

12. The rectifier of claim 10, wherein each rectifier cell is arranged to generate, on closure of the electronic switch of that cell, at least one signal controlling the opening of the electronic switch of another rectifier cell associated with the same DC bus polarity.

13. The rectifier of claim 10, wherein the rectifier devices are diodes.

14. The rectifier of claim 10, wherein the electronic switches are IGBTs.

15. The rectifier of claim 10, wherein each rectifier cell receives signals controlling the opening of the electronic switch from other cells associated with the same DC bus polarity.

16. The rectifier of claim 10, the polyphase network being three-phase.

17. The rectifier as claimed in claim 10, wherein each rectifier cell comprises an independent electric power supply.

18. The rectifier of claim 17, wherein the power supply is arranged to deliver a first voltage that is negative relative to the reference used to control the electronic switches and a second voltage that is positive relative to this reference.

19. The rectifier of claim 10, wherein the control means are analog.

20. The rectifier of claim 10, wherein the control means are arranged to provoke the opening of an electronic switch in the event of an overcurrent in the latter.

21. The rectifier of claim 10, wherein the rectifier cells are substantially identical.

22. The rectifier of claim 10, wherein the control means are arranged to inhibit the closure of the electronic switch following an abrupt variation of the voltage at the terminals of the rectifier device, generated on the opening of the electronic switch of the cell connected to the same phase of the network and to the opposite DC bus polarity.

23. The rectifier of claim 22, wherein the control means are arranged to inhibit, for a given rectifier cell, the closure of the electronic switch in a predefined angular range, on the one hand between 60°

+Δ

φ

₁ and 300°

−

Δ

φ

₂ and including on the other hand the range 120°

−

Δ

φ

₃ and 240°

+Δ

φ

₄, with Δ

φ

₁>

0, Δ

φ

₂>

0, Δ

φ

₃>

0 and Δ

φ

₄>

t_e, where t_e is the encroachment time, the angular reference being taken at the summit of the arch during which the rectifier device of the rectifier cell concerned is passing.

24. The rectifier of claim 21, wherein the control means include a filtering stage with saturation of the signal differential.

29. A system for controlling the speed of an electric motor comprising a reversible rectifier as claimed in claim 10.

30. A system for controlling a generator comprising a reversible rectifier as defined in claim 10.

31. The system as claimed in claim 30, wherein the generator is a wind generator.

32. An energy recovery system comprising a reversible rectifier as defined in claim 10 and a quasi current source.

33. The system as claimed in claim 32, wherein the quasi current source comprises solar panels.

25. A rectifier cell comprising:

a rectifier device,

a one-way electronic switch connected in anti-parallel with the rectifier device,

control means arranged to;

control the closure of the electronic switch when the rectifier device becomes passing,

when the electronic switch is closed, deliver to at least one other cell, a signal controlling the opening of an electronic switch of that at least one other cell, and

receive from at least one other cell a signal controlling the opening of the electronic switch and open that electronic switch on receipt of this signal.

26. The cell as claimed in claim 25, comprising an independent electric power supply.

27. The cell as claimed in claim 25, comprising a filtering stage with saturation of the signal differential.

28. The cell as claimed in claim 25, taking the form of a single component or module, the latter comprising an input to be connected to a phase of the network, an output to be connected to a polarity of the DC bus, at least one input to receive the open control signal from another cell and at least one output to send an open control signal to another cell.

34. A system for controlling the speed of an electric motor comprising:

a reversible rectifier to be connected to a polyphase electricity network and connected to a DC bus, this rectifier comprising a plurality of rectifier cells each rectifier cell comprising a rectifier device and a one-way electronic switch, connected in anti-parallel with the rectifier device, the rectifier devices of the various cells being arranged so as to form a rectifier, each rectifier cell comprising means of controlling the electronic switch of the cell arranged to close the latter after detecting a conduction of the rectifier device of the cell so as to enable current to be returned to the network, the control means being arranged to receive a signal external to the cell, controlling the opening of the electronic switch, from another rectifier cell,

a power stage connected to the DC bus and to be connected to the electric motor.

35. The system of claim 34, comprising a filtering stage for the DC bus comprising at least one capacitor, the capacitance of the at least one capacitor of the filtering stage being less than or equal to 5 μ

F per kW of power supplied.

36. The system of claim 34, wherein the control means are arranged to inhibit a closure of the electronic switch following an abrupt variation of the voltage at the terminals of the rectifier device, generated on the opening of the electronic switch of the cell connected to the same phase of the network and to the opposite DC bus polarity.

37. The system of claim 34, wherein the control means are arranged to inhibit, for a given rectifier cell, the closure of the electronic switch in a predefined angular range, on the one hand between 60°

+Δ

φ

₁ and 300°

−

Δ

φ

₂ and including on the other hand the range 120°

−

Δ

φ

₃ and 240°

+Δ

φ

₄, with Δ

φ

₁>

0, Δ

φ

₂>

0, Δ

φ

₃>

0 and Δ

φ

₄>

t_e, where t_e is the encroachment time, the angular reference being taken at the summit of the arch during which the rectifier device of the rectifier cell concerned is passing.