Inductive clamping circuit

Patent metadata

Field	Value
Publication number	US-2016149505-A1
Application number	US-201414551160-A
Country	US
Kind code	A1
Filing date	Nov 24, 2014
Priority date	Nov 24, 2014
Publication date	May 26, 2016
Grant date	—

Abstract

A power control circuit includes a solid state power controller operable to connect an AC power source to a load. The solid state power controller includes a first switching device and a second switching device arranged serially. Each of the switching devices includes a diode, a controller controllably coupled to each of the first switching device and the second switching device, such that the controller is capable of controlling an on/off state of the first switching device and the second switching device. The controller further includes a non-transitory memory storing instructions for causing the controller to perform the steps of: switching off a first switching device having a diode aligned with a current polarity of an AC current flow prior to a first zero crossing, delaying a switching off of a second switching device until after the first zero crossing, and switching the second switching device off after the delay and before a second zero crossing.

First claim

1 . A method for switching off an inductive load comprising:
switching off a first switching device having a diode aligned with a current polarity of an AC current flow prior to a first zero crossing; delaying a switching off of a second switching device until after said first zero crossing; and switching the second switching device off after said delay and before a second zero crossing.

2 . The method of claim 1 , wherein each of said first switching device and said second switching device is a MOSFET.

3 . The method of claim 1 , wherein there are no intervening zero crossings between the second zero crossing and the first zero crossing.

4 . The method of claim 1 , wherein switching off a first switching device having a diode aligned with a current polarity of an AC current flow prior to a first zero crossing comprises causing a diode of the first switching device to operate as a freewheeling diode, thereby allowing current in the inductive load to continue to flow.

5 . The method of claim 1 , wherein switching the second switching device off after said delay and before a second zero crossing occurs when a half cycle of the AC current is approximately 90 degrees past the first zero crossing.

6 . The method of claim 1 , further comprising determining a current polarity of an AC current flowing into an inductive load prior to switching off the first switching device.

7 . The method of claim 6 , wherein determining a current polarity of an AC current flowing into an inductive load prior to switching off the first switching device further comprises determining a corresponding switching device having an aligned diode.

8 . The method of claim 1 , wherein delaying a switching off of a second switching device until after said first zero crossing comprises delaying switching of the second switching device for one of a predetermined period of time period and a time period defined as elapsing when the current has completely stopped flowing.

9 . The method of claim 1 , wherein delaying a switching off of a second switching device until after said first zero crossing comprises determining a required delay length such that said switching the second switching device off after said delay and before a second zero crossing occurs between the first zero crossing and the second zero crossing.

10 . The method of claim 1 , wherein switching off a first switching device having a diode aligned with a current polarity of an AC current flow prior to a first zero crossing further comprises switching off a second switching device having a diode unaligned with a current polarity of an AC current flow when a load fault is detected, thereby bypassing the steps of delaying a switching off of a second switching device until after said first zero crossing, and switching the second switching device off after said delay and before a second zero crossing.

11 . A power control circuit comprising:
a solid state power controller operable to connect an AC power source to a load, wherein the solid state power controller includes a first switching device and a second switching device arranged serially and wherein each of said switching devices includes a diode, a controller controllably coupled to each of said first switching device and said second switching device, such that said controller is capable of controlling an on/off state of said first switching device and said second switching device; said controller further including a non-transitory memory storing instructions for causing the controller to perform the steps of: switching off a first switching device having a diode aligned with a current polarity of an AC current flow prior to a first zero crossing; delaying a switching off of a second switching device until after said first zero crossing; and switching the second switching device off after said delay and before a second zero crossing.

12 . The power control circuit of claim 11 , wherein said controller is a component of said solid state power controller.

13 . The power control circuit of claim 11 , wherein said controller is an independent controller.

14 . The power control circuit of claim 11 , wherein said first switching device is a MOSFET and said second switching device is a MOSFET.

15 . The power control circuit of claim 11 , wherein said first switching device is a MOSFET transistor network and said second switching device is a MOSFET transistor network.

16 . The power control circuit of claim 11 , further comprising an AC power source connected to said solid state power controller, such that said solid state power controller is operable to control a flow of AC power from said AC power source to a load connected to the solid state power controller.

Assignees

• Hamilton Sundstrand Corp

Inventors

• Dickey John A

Classifications

• H02M5/293 Primary

  using semiconductor devices only · CPC title