Ground fault minimization

Patent metadata

Field	Value
Publication number	US-10756532-B2
Application number	US-201916503786-A
Country	US
Kind code	B2
Filing date	Jul 5, 2019
Priority date	Jul 13, 2018
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

A circuit for minimizing energy provided to a ground fault includes a source, a multiple switches, an output filter, and a controller. The switches include a first side pair of switches and a second side pair of switches configured to provide an output signal based on the source. The output filter includes one or more energy storage elements coupled to the first side pair of switches or the second side pair of switches. The controller is configured to receive a ground fault signal that indicates a fault has occurred and configured to generate a switch signal for the switches for a minimum energy state of the output filter and in response to the ground fault signal.

First claim

We claim:

1. A circuit for minimizing energy provided to a ground fault, the circuit comprising:
a source;
a plurality of switches including a first side pair of switches and a second side pair of switches configured to provide an output signal based on the source;
an output filter including one or more energy storage elements coupled to the first side pair of switches or the second side pair of switches; and
a controller configured to receive a ground fault signal that indicates a fault has occurred and configured to generate a switch signal for the plurality of switches for a minimum energy state of the output filter and in response to the ground fault signal,
wherein the one or more energy storage elements includes:
a first inductor coupled to at least the first side pair of switches of the plurality of switches;
a second inductor coupled to at least the second side pair of switches of the plurality of switches; and
at least one capacitor coupled to the first inductor and the second inductor for an output of the circuit for ground fault correction.

2. The circuit of claim 1 , wherein the switch signal in response to the ground fault signal changes a state of at least one of the plurality of switches.

3. The circuit of claim 1 , wherein the at least one of the plurality of switches includes the first side pair of switches and the second side pair of switches.

4. The circuit of claim 1 , wherein the switch signal in response to the ground fault signal reverses a plurality of the outputs of the circuit for ground fault correction.

5. The circuit of claim 1 , wherein the ground fault signal is generated by an external ground fault detector.

6. The circuit of claim 1 , wherein the ground fault signal is detected from an impedance from the output filter to ground.

7. The circuit of claim 6 , wherein the impedance is a capacitive impedance or a resistive impedance.

8. The circuit of claim 1 , wherein the switch signal is configured to change the plurality of switches to control the output signal to zero voltage.

9. The circuit of claim 8 , wherein a time elapsed between a receipt of the ground fault signal at the output signal reaching substantially zero voltage is less than a quarter cycle of the output signal.

10. The circuit of claim 1 , wherein the switch signal includes a first pulse width modulated signal for the first side pair of switches and a second pulse width modulated signal for the second side pair of switches.

11. The circuit of claim 1 , wherein energy is actively removed from the output filter and stored internal to an inverter including the circuit after a ground fault signal is received.

12. A method for ground fault correction, the method comprising:
providing an output signal via a plurality of switches including a first side pair of switches coupled to a first inductor and a second side pair of switches coupled to a second inductor, wherein at least one capacitor for the output signal is coupled to the first inductor or the second inductor;
receiving, at a controller, a ground fault signal that indicates a fault has occurred; and
generating a switch signal for the plurality of switches in response to the ground fault signal, the switch signal actively controlling the output signal to a threshold.

13. The method of claim 12 , wherein the output signal is a voltage and the threshold is zero.

14. The method of claim 12 , wherein the switch signal in response to the ground fault signal reverses a plurality of the outputs for ground fault correction.

15. The method of claim 12 , wherein the ground fault signal is generated by an external ground fault detector.

16. The method of claim 12 , wherein the ground fault signal is detected from an impendence from an output filter to ground.

17. An apparatus comprising:
an inverter circuit including an input and an output;
a ground fault sensor coupled to the inverter circuit and configured to generate a fault signal that indicates a ground fault has occurred;
a controller configured to receive the ground fault signal and generate a reverse signal for operation of the inverter circuit that reverses energy from the output of the inverter circuit to the input of the inverter circuit; and
a plurality of switches in the inverter circuit including a first side pair of switches and a second side pair of switches configured to provide the output, wherein the reverse signal changes a state of the first side pair of switches or the second side pair of switches,
at least one inductor coupled to at least the first side pair of switches of the plurality of switches or coupled to at least the second side pair of switches of the plurality of switches; and
at least one capacitor coupled to the first inductor or the second inductor.

Assignees

• Kohler Co

Inventors

• Frampton Isaac S
• Larson Adam

Classifications

• H02M1/12

  Arrangements for reducing harmonics from AC input or output · CPC title

• H02H9/08 Primary

  Limitation or suppression of earth fault currents, e.g. Petersen coil · CPC title

• H02M1/32

  Means for protecting converters other than automatic disconnection · CPC title

• H02M7/53871

  with automatic control of output voltage or current · CPC title

• H02H7/1227 Primary

  responsive to abnormalities in the output circuit, e.g. short circuit · CPC title