Pyro igniter circuit and testing method

1. A pyro igniter circuit comprising:

a shunt resistor connected in series with a power line;

an amplifier having first and second inputs respectively electrically connected to first and second terminals of the shunt resistor;

a pyro igniter disconnect element electrically connected to an output of the amplifier and configured to cut the power line based on an ignition control signal received from the output of the amplifier;

a coupling resistor electrically interconnected between the first input of the amplifier and the first terminal of the shunt resistor; and

a supervisory circuit electrically connected to a node, the node being interconnected between the first input of the amplifier and the coupling resistor,

wherein the supervisory circuit is configured to:

transmit a test signal to the node, the test signal having a pulse duration time below an igniter activation pulse time of the pyro igniter disconnect element and/or the ignition control signal, in response to the transmitted test signal, has an amplitude below an igniter activation amplitude of the pyro igniter disconnect element; and

receive a diagnostic response signal in response to the transmitted test signal.

2. The pyro igniter circuit of claim 1 , wherein the supervisory circuit is electrically connected to the output of the amplifier to receive the ignition control signal in response to the transmitted test signal.

3. The pyro igniter circuit of claim 1 , further comprising a first current sensor configured to:

measure an electric current on an output line between the output of the amplifier and the pyro igniter disconnect element; and

transmit a first current signal as the diagnostic response signal indicative of the measured electric current to the supervisory circuit.

4. The pyro igniter circuit of claim 1 , further comprising a second current sensor configured to:

measure an electric current at the node in response to the transmitted test signal; and

transmit a second current signal as the diagnostic response signal indicative of the measured electric current to the supervisory circuit.

5. The pyro igniter circuit of claim 1 , wherein the pulse duration time is less than 20 μs.

6. The pyro igniter circuit of claim 5 , wherein the pulse duration time is less than 10 μs.

7. The pyro igniter circuit of claim 6 , wherein the pulse duration time is less than 1 μs.

8. The pyro igniter circuit of claim 1 , wherein the pulse duration time of the test signal is below the igniter activation pulse time of the pyro igniter disconnect element, and the ignition control signal, in response to the transmitted test signal, has an amplitude above the igniter activation amplitude of the pyro igniter disconnect element.

9. The pyro igniter circuit of claim 1 , wherein the pulse duration time of the test signal is above the igniter activation pulse time of the pyro igniter disconnect element, and the ignition control signal, in response to the transmitted test signal, has an amplitude below an igniter activation amplitude of the pyro igniter disconnect element.

10. The pyro igniter circuit of claim 1 , wherein the supervisory circuit is configured to compare the received diagnostic response signal with the transmitted test signal.

11. The pyro igniter circuit of claim 10 , wherein the supervisory circuit is configured to generate a state signal based on the comparison of the received diagnostic response signal and the transmitted test signal.

12. A battery system comprising the pyro igniter circuit according to claim 1 and a plurality of battery cells electrically connected to the power line.

13. An electric vehicle comprising the battery system according to claim 12 .

14. A testing method for testing a pyro igniter circuit, the pyro igniter circuit comprising a shunt resistor connected in series with a power line, an amplifier comprising first and second inputs respectively electrically connected to first and second terminals of the shunt resistor, a pyro igniter disconnect element electrically connected to an output of the amplifier and configured to cut the power line based on an ignition control signal received from the output of the amplifier, a coupling resistor electrically interconnected between the first input of the amplifier and the first terminal of the shunt resistor, the method comprising:

transmitting a test signal to a node, the node being interconnected between the first input of the amplifier and the coupling resistor, the test signal having a pulse duration time below an igniter activation pulse time of the pyro igniter disconnect element and/or the ignition control signal, in response to the transmitted test signal, having an amplitude below an igniter activation amplitude of the pyro igniter disconnect element; and

receiving a diagnostic response signal in response to the transmitted test signal.

15. The method of claim 14 , further comprising receiving an ignition control signal as the diagnostic response signal from the output of the amplifier in response to the transmitted test signal.

16. The method of claim 14 , further comprising:

measuring an electric current on an output line between the output of the amplifier and the pyro igniter disconnect element in response to the transmitted test signal; and

transmitting a first current signal as the diagnostic response signal indicative of the measured electric current to a supervisory circuit.

17. The method of claim 14 , further comprising:

measuring an electric current at the node in response to the transmitted test signal; and

transmitting a second current signal as the diagnostic response signal indicative of the measured electric current to a supervisory circuit.