Fault detection for a solid state power converter

Patent metadata

Field	Value
Publication number	US-11977131-B2
Application number	US-202016951269-A
Country	US
Kind code	B2
Filing date	Nov 18, 2020
Priority date	Nov 18, 2020
Publication date	May 7, 2024
Grant date	May 7, 2024

Abstract

In some examples, an electrical power system includes a solid state power converter including a first set of switches on a source side of the solid state power converter and a second set of switches on a load side of the solid state power converter. The electrical power system also includes a power source connected to the source side of the solid state power converter and also includes a differential bus connected to the load side of the solid state power converter. The electrical power system further includes a controller configured to receive a first signal indicating a current at the source side and receive a second signal indicating a current at the load side. The controller is further configured to detect, based on a time derivative of the first signal and a time derivative of the second signal, a fault in the electrical power system.

First claim

What is claimed is:

1. An electrical power system comprising:
a solid state power converter including a first set of switches on a source side of the solid state power converter and a second set of switches on a load side of the solid state power converter;
a power source connected to the source side of the solid state power converter;
a differential bus connected to the load side of the solid state power converter; and
a controller configured to:
receive, during a first time period, a first signal indicating a current at the source side of the solid state power converter;
receive, during the first time period, a second signal indicating a current at the load side of the solid state power converter;
determine a time derivative of the first signal which represents a rate of change of the current at the source side during the first time period;

determine a time derivative of the second signal which represents a rate of change of the current at the load side during the first time period;
detect, based on the time derivative of the first signal and the time derivative of the second signal, a fault in the electrical power system; and
in response to detecting the fault based on the time derivative of the first signal and the time derivative of the second signal, cause the first set of switches to open.

2. The electrical power system of claim 1 , wherein the controller is configured to:
determine that a magnitude of the time derivative of the first signal is greater than a first threshold level;
determine that a magnitude of the time derivative of the second signal is greater than a second threshold level; and
detect the fault in response to:
determining that the magnitude of the time derivative of the first signal is greater than the first threshold level; and
determining that the magnitude of the time derivative of the second signal is greater than the second threshold level.

3. The electrical power system of claim 2 , wherein the controller is configured to:
determine, at a first time, that the magnitude of the time derivative of the first signal is greater than the first threshold level;
determine, at a second time at least a threshold time duration after the first time, that the magnitude of the time derivative of the first signal is greater than the first threshold level; and
detect the fault in response to:
determining that the magnitude of the time derivative of the first signal is greater than the first threshold level at the first time; and
determining that the magnitude of the time derivative of the first signal is greater than the first threshold level at the second time.

4. The electrical power system of claim 1 , wherein the controller is configured to:
determine that a magnitude of a second time derivative of the first signal is less than a first threshold level;
determine that a magnitude of a second time derivative of the second signal is less than a second threshold level; and
detect the fault in response to:
determining that the magnitude of the second time derivative of the first signal is less than the first threshold level; and
determining that the magnitude of the second time derivative of the second signal is less than the second threshold level.

5. The electrical power system of claim 1 , wherein the controller is configured to:
determine that a magnitude of the first signal is not greater than a first threshold level;
determine that a magnitude of the second signal is greater than a second threshold level; and
determine, in response to determining that the magnitude of the first signal is not greater than the first threshold level and determining that the magnitude of the second signal is greater than the second threshold level, that the fault occurred on the load side of the solid state power converter.

6. The electrical power system of claim 1 , wherein the controller is configured to:
determine that a magnitude of the time derivative of the first signal is not greater than a first threshold level;
determine that a magnitude of the time derivative of the second signal is greater than a second threshold level; and
determine, in response to determining that the magnitude of the time derivative of the first signal is not greater than the first threshold level and determining that the magnitude of the time derivative of the second signal is greater than the second threshold level, that the fault occurred on the load side of the solid state power converter.

7. The electrical power system of claim 1 , wherein the controller is configured to:
determine a sum of the time derivative of the first signal and the time derivative of the second signal;
determine that the sum is greater than a threshold level; and
detect the fault in response to determining that the sum is greater than the threshold level.

8. The electrical power system of claim 7 , wherein the controller is configured to:
determine, at a first time, that the sum is greater than the threshold level;
determine, at a second time at least a threshold time duration after the first time, that the sum is greater than the threshold level; and
detect, in response to determining that the sum is greater than the threshold level at the first time and determining that the sum is greater than the threshold level at the second time, the fault.

9. The electrical power system of claim 1 ,
wherein the solid state power converter further comprises a middle capacitor connected between the first set of switches and the second set of switches, and
wherein the controller is configured to:
detect the fault based on the time derivative of the first signal and further based on the time derivative of the second signal by detecting the fault in a first instance;
receive a third signal indicating a voltage at the source side of the solid state power converter;
receive a fourth signal indicating a voltage across the differential bus;
receive a fifth signal indicating a voltage across the middle capacitor; and
detect a second instance of the fault based on a first difference between the third signal and the fifth signal and further based on a second difference between the fifth signal and the fourth signal.

10. The electrical power system of claim 9 , wherein the controller is configured to:
determine, at a first time, that the first difference is not greater than a first threshold level and that the second difference is greater than a second threshold level;
determine, at a second time at least a threshold time duration after the first time, that the first difference is not greater than a first threshold level and that the second difference is greater than a second threshold level; and
detect the second instance of the fault in response to:
determining that the first difference is not greater than the first threshold level and that the second difference is greater than the second threshold level at the first time; and
determining that the first difference is not greater than the first threshold level and that the difference is greater than the second threshold level at the second time.

11. The electrical power system of claim 1 , wherein the controller is configured to:
determine that the fault occurred at the load side of the solid state power converter;
deactivate the first set of switches in response to determining that the fault occurred at the load side;
determine, after deactivating the first set of switches, that a voltage across a middle capacitor of the solid state power converter is less than a threshold voltage; and
deactivate the second set of switches in response to determining that the voltage across the middle capacitor is less than the threshold volt

Assignees

• Rolls Royce Nam Tech Inc
• Rolls Royce Singapore Pte Ltd

Inventors

• Yang Yu
• Gajanayake Chandana Jayampathi
• Loder David
• Gupta Amit Kumar

Classifications

• G01R31/56 Primary

  Testing of electric apparatus (testing of transformers G01R31/62; testing of connections G01R31/66) · CPC title

• G01R19/16566

  Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 · CPC title

• H02H1/0007

  concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445) · CPC title

• H02H7/1203

  Circuits independent of the type of conversion · CPC title

• G01R31/42 Primary

  AC power supplies · CPC title