Converter apparatus using source-activated discharge circuits

Patent metadata

Field	Value
Publication number	US-10873270-B2
Application number	US-201715467711-A
Country	US
Kind code	B2
Filing date	Mar 23, 2017
Priority date	Mar 23, 2017
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

An apparatus, such as a variable frequency drive (VFD), includes a rectifier, a DC bus coupled to an output of the rectifier and at least one capacitor coupled to the DC bus. The apparatus further includes a normally-conducting switch coupled to the DC bus and configured to discharge the at least one capacitor in a conducting state and a control circuit configured to control the normally-conducting switch responsive to an input to the rectifier. The control circuit may be configured to control the normally-conducting switch responsive to a voltage at the input of the rectifier. The control circuit may include a regulator circuit having an input coupled to the input of the rectifier and a driver circuit coupled to an output of the regulator circuit and configured to drive a control terminal of the normally-conducting switch.

First claim

That which is claimed:

1. An apparatus comprising:
a rectifier;
a DC bus coupled to an output of the rectifier;
at least one capacitor coupled to the DC bus;
at least one n-channel depletion-mode FET and a resistor coupled in series to the DC bus; and
a control circuit configured to cause the at least one n-channel depletion-mode FET to transition from a non-conducting state to a conducting state responsive to a decrease in an AC voltage at an input to the rectifier to thereby discharge the at least one capacitor via the at least one n-channel depletion-mode FET and the resistor, the control circuit comprising:
a regulator circuit having an input coupled to the input of the rectifier; and
an inverting DC-DC converter having an input coupled to the regulator circuit and an output coupled to a control terminal of the at least one n-channel depletion-mode FET.

2. The apparatus of claim 1 , comprising a supercascode switch including the at least one n-channel depletion-mode FET.

3. The apparatus of claim 1 , wherein the control circuit is further configured to control the at least one n-channel depletion-mode FET responsive to a voltage on the DC bus.

4. A motor drive comprising:
a rectifier having an input configured to be coupled to an AC power source;
a DC bus coupled to an output of the rectifier;
an inverter having an input coupled to the DC bus and an output configured to be coupled to a motor;
at least one capacitor coupled to the DC bus; and
a normally-on or normally-closed switch and a resistor coupled in series to the DC bus; and
a control circuit coupled to the input of the rectifier and configured to cause the normally-on or normally-closed switch to transition from a non-conducting state to a conducting state responsive to a decrease in an AC voltage at the input of the rectifier to thereby discharge the at least one capacitor through the normally-on or normally-closed switch and the resistor, the control circuit comprising:
a regulator circuit having an input coupled to the input of the rectifier; and
a DC-DC converter circuit coupled to an output of the regulator circuit and configured to drive a control terminal of the normally-on or normally-closed switch.

5. The motor drive of claim 4 , wherein the control circuit is configured to place the normally-on or normally-closed switch in the non-conducting state responsive to the voltage at the input of the rectifier meeting a predetermined criterion.

6. The motor drive of claim 4 , wherein the normally-on or normally-closed switch comprises at least one depletion-mode FET.

7. The motor drive of claim 6 , wherein the at least one depletion-mode FET comprises at least one n-channel depletion-mode FET and wherein the DC-DC converter circuit comprises an inverting DC-DC converter circuit having an input coupled to the regulator circuit and an output coupled to a control terminal of the at least one n-channel depletion-mode FET.

8. The motor drive of claim 6 , wherein the normally-on or normally-closed switch comprises a normally-on supercascode switch comprising at least one depletion-mode FET.

9. The motor drive of claim 4 , wherein the control circuit is further configured to control the normally-on or normally-closed switch responsive to a voltage on the DC bus.

10. An apparatus comprising:
a normally-on or normally-closed switch and a resistor configured to be coupled in series to a DC bus of a motor drive; and
a control circuit configured to cause the normally-on or normally-closed switch to transition from a non-conducting state to a conducting state responsive to a reduction in an AC voltage at an input of a rectifier coupled to the DC bus to thereby discharge at least one capacitor coupled to the DC bus through the normally-on or normally-closed switch and the resistor; the control circuit comprising:
a regulator circuit having an input coupled to the input of the rectifier; and
a DC-DC converter circuit coupled to an output of the regulator circuit and configured to drive a control terminal of the normally-on or normally-closed switch.

11. The apparatus of claim 10 , wherein the control circuit is configured to place the normally-on or normally-closed switch in a non-conducting state responsive to the voltage at the input of the rectifier having a magnitude exceeding a threshold.

12. The apparatus of claim 10 , wherein the normally-on or normally-closed switch comprises at least one depletion-mode FET.

13. The apparatus of claim 12 , wherein the at least one depletion-mode FET comprises at least one n-channel depletion-mode FET and wherein the DC-DC converter circuit comprises an inverting DC-DC converter.

14. The motor drive of claim 12 , wherein the normally-on or normally-closed switch comprises a normally-on supercascode circuit comprising the least one depletion-mode FET.

Assignees

• Eaton Intelligent Power Ltd

Inventors

• Simms Stan Rex
• Maurin John David
• Farr Thomas Arthur

Classifications

• H02M1/322

  Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock · CPC title

• H02M7/06 Primary

  using discharge tubes without control electrode or semiconductor devices without control electrode · CPC title

• H02J7/345

  using capacitors as storage or buffering devices · CPC title

• H02P29/027

  the fault being an over-current · CPC title

• H02M2001/322

  Electricity · mapped topic