ACTIVE SNUBBER

• US 20170257022A1
• Filed: 11/16/2015
• Published: 09/07/2017
• Est. Priority Date: 11/21/2014
• Status: Active Grant

• Current Assignee: Maschinenfabrik Reinhausen GmbH (Richard Scheubeck Beteiligungs-Gmbh & Co. KG)
• Original Assignee: Maschinenfabrik Reinhausen GmbH (Richard Scheubeck Beteiligungs-Gmbh & Co. KG)
• Inventors: BRYANT, Angus
• Granted Patent: US 10,044,258 B2
• Time in Patent Office: Days
• CPC Class Codes: H02M 1/0048 Circuits or arrangements for reducing losses using snubbers H02M1/34
• CPC Class Codes: H02M 1/0095 Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck
• CPC Class Codes: H02M 1/088 for the simultaneous control of series or parallel connected semiconductor devices
• CPC Class Codes: H02M 1/34 Snubber circuits
• CPC Class Codes: H02M 1/342 Active non-dissipative snubbers
• CPC Class Codes: H02M 1/344 Active dissipative snubbers
• CPC Class Codes: H02M 3/04 by static converters
• CPC Class Codes: H02M 5/04 by static converters controlling transformers, reactors or choke coils, e.g. by tap changing H02P13/00
• CPC Class Codes: H02M 7/4835 comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
• CPC Class Codes: H02M 7/4837 Flying capacitor converters
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The present invention generally relates to a switching cell for a phase leg of a power converter and a method of controlling a power converter to drive a load, and more particularly to a plurality of such switching cells, a phase arm for a power converter, a power converter phase leg, to a power converter for driving a load, and methods of making a power converter. A switching cell for a phase leg of a power converter may comprise: a power switch for conducting a current for driving a load; a commutation path coupled in parallel with the power switch, the commutation path comprising a cell capacitor and an auxiliary switch coupled in series, the auxiliary switch configured to allow control of a conduction state of the commutation path; and a cell inductor coupled to a coupling of the power switch and the commutation path, wherein the switching cell comprises at least one control input line for receiving a control signal, the at least one control input line configured to drive a control terminal of the power switch and a control terminal of the auxiliary switch.

Claims

1. A switching cell for a phase leg of a power converter, the switching cell comprising:

a power switch for conducting a current for driving a load;

a series connection comprising an auxiliary switch and a cell capacitor coupled in series, the series connection coupled in parallel with the power switch;

a cell inductor coupled to a coupling of the power switch and the series connection; and

a commutation loop to conduct a commutation current arising from turn-off of the power switch, the loop comprising;

a first bypass circuit for blocking current flow in a direction and coupled in parallel with the power switch to conduct the commutation current in another, opposite direction;

a second bypass circuit for blocking current flow in a direction and coupled in parallel with the auxiliary switch to conduct the commutation current in another, opposite direction; and

the cell capacitor; and

at least one control input line for receiving a control signal and configured to drive a control terminal of the power switch and a control terminal of the auxiliary switch.

2. The switching cell of claim 1, wherein at least one of the first and second bypass circuits comprises an extrinsic diode.

3. The switching cell of claim 1, wherein the first and second bypass circuits comprise an intrinsic diode of the power switch as the first bypass circuit or an intrinsic diode of the auxiliary switch as the second bypass circuit.

4. The switching cell of claim 1, further comprising a control terminal drive input line configured to simultaneously turn either the power switch or the auxiliary switch ON and the other of the power switch and the auxiliary switch OFF.

5. The switching cell of claim 1, wherein one of the power switch and auxiliary switch comprises an n-type device and the other of the power switch and the auxiliary switch comprises a p-type device, the switching cell configured to control switching of the power switch and the auxiliary switch according to a control signal in common.

6. A plurality of switching cells of claim 1, further comprising:

a series connection of the switching cells, each switching cell of the at least one series connection being coupled to an adjacent one of the switching cells by a respective one of the cell inductors.

7. The plurality of switching cells of claim 6, further comprising at least one switching cell coupled in parallel with a one of the switching cells of the series connection of switching cells.

8. The plurality of switching cells of claim 6, wherein at least one of the power switches comprises a wide bandgap semiconductor device.

9. The plurality of switching cells of claim 6, wherein an auxiliary switch of at least one of the switching cells is physically smaller than the power switch of the switching cell.

10. The plurality of switching cells of claim 6, wherein an auxiliary switch of at least one of the switching cells has lower power rating than the power switch of the switching cell.

11. The plurality of switching cells of claim 6, wherein at least one of the power switches comprises an IGBT, MOSFET, HEMT, BJT, JFET, GTO or GCT.

12. The plurality of switching cells of claim 6, wherein each of at least some of the switching cells of the plurality comprises a vertical FET device or a lateral HEMT as the power switch.

13. The plurality of switching cells of claim 6, wherein at least one of the switching cells has a resistor in parallel with the cell inductor of the respective switching cell.

14. The plurality of switching cells of claim 6, comprising:

a drive circuit for driving a control terminal of the power switch or a control terminal of the auxiliary switch of one of the switching cells, the drive circuit configured to draw power from the switching cell.

15. A phase arm for a power converter, the phase arm comprising a plurality of switching cells of claim 6.

16. A power converter phase leg having arms coupled together to provide an output signal for driving a load, at least one the arms according to claim 15.

17. A power converter for driving a load, the power converter comprising at least one power converter phase leg of claim 16, each of the phase legs having an output line for driving a phase input of a respective load, the power converter further comprising a link capacitor, the one phase leg and the link capacitor being coupled between a first power rail and a second power rail.

18. The power converter according to claim 16, wherein the power converter is a multilevel converter.

19. A method of making a power converter, the method comprising the steps of:

obtaining a power converter comprising a phase arm having at least one IGBT and

replacing the phase arm with a phase arm according to claim 15, at least one of the switching cells of the replacement phase arm having wide bandgap semiconductor device as the power switch of the switching cell.

20. A method of making a power converter, the method comprising the steps of:

obtaining a power converter comprising a phase arm having a turn-on snubber and a GTO module, and

replacing the turn-on snubber and at least one GTO module with a phase arm according to claim 15.

21. A method of controlling a power converter to drive a load, the power converter having a phase leg coupled between two power rails and comprising two arms each having a plurality of switching cells and coupled at an output of the converter, wherein each of the switching cells comprises:

a respective power switch for conducting a current for driving a load;

a respective series connection comprising an auxiliary switch and a cell capacitor coupled in series, the series connection coupled in parallel with the power switch;

a respective cell inductor coupled to a coupling of the power switch and the series connection; and

a commutation loop to conduct a commutation current arising from turn-off of the power switch, the loop comprising;

a first bypass circuit for blocking current flow in a direction and coupled in parallel with the power switch to conduct a commutation current in another, opposite direction;

a second bypass circuit for blocking current flow in a direction and coupled in parallel with the auxiliary switch to conduct a commutation current in another, opposite direction; and

the cell capacitor,

the method comprising at least one step of switching a first number of switching cells of one the arms ON and a second number of the switching cells of the other arm OFF to advance a voltage profile at the output of the converter and maintain a voltage across the phase leg, switching of a switching cell ON comprising turning the power switch of the switching cell ON and the auxiliary switch of the switching cell OFF, the first and second numbers being one or more.

22. The method of claim 21, wherein at least two of the switching cells of an arm are coupled in parallel, the method comprising switching the parallel-connected cells at different times.

23. The method of claim 21, wherein each of the arms comprises an array having a number NS of rows and a number NP of columns of the switching cells, wherein

the numbers NS and NP are one or more,

each of the columns comprises a series connection of the switching cells coupled between a respective one of the power rails and the converter output, and

the method comprises less than or equal to NS×

NP steps to generate the voltage profile.

24. The method of claim 21, wherein the voltage profile varies between a voltage of one of the power rails and a voltage of the other of the power rails.

25. The method of claim 21, further comprising the step of:

determining a switching firing pattern of the switching cells according to a dv/dt value of a voltage profile transition.

26. (canceled)