Method and system for overcurrent protection for insulated-gate bipolar transistor (IGBT) modules

• US 9,912,225 B2
• Filed: 01/29/2016
• Issued: 03/06/2018
• Est. Priority Date: 10/30/2015
• Status: Active Grant

• Current Assignee: Faraday & Future Inc.
• Original Assignee: Faraday & Future Inc.
• Inventors: Schulz, Steven E., Tang, David, Hiti, Silva, Romo, Hector, Haeberlin, Marc
• Primary Examiner(s): AHMED, YUSEF A
• Application Number:
  US15/011,364
• Publication Number:
  US 20170126115A1
• Time in Patent Office: 767 Days
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 3/003 relating to inverters
• CPC Class Codes: B60L 3/0038 relating to sensors
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current
• CPC Class Codes: H03K 17/0828 in composite switches
• CPC Class Codes: H03K 2017/0806 against excessive temperature
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

Circuits and methods for driving a load are disclosed. An exemplary driving circuit may include first and second switching devices electrically connected with each other in parallel. The driving circuit may also include a current sensing circuit configured to generate a current sensing signal indicating a value of a current flowing through the first switching device. The current sensing signal may include an offset caused by parasitic inductance imbalance in electrical connections connecting the first and second switching devices. The driving circuit may further include a driver circuit configured to control switching operations of the first and second switching devices. The driver circuit may include an overcurrent protection circuit electrically connected to the current sensing circuit. In addition, the driving circuit may include a current sensing signal correction circuit configured to reduce the offset in the current sensing signal received by the overcurrent protection circuit during a switching transient period.

Claims

1. A driving circuit for driving a load, comprising:

first and second switching devices electrically connected with each other in parallel;

a current sensing circuit configured to generate a current sensing signal indicating a value of a current flowing through the first switching device, the current sensing signal including an offset caused by parasitic inductance imbalance in electrical connections connecting the first and second switching devices;

a driver circuit electrically connected to the first and second switching devices and configured to control switching operations of the first and second switching devices, the driver circuit including an overcurrent protection circuit electrically connected to the current sensing circuit for receiving the current sensing signal;

a current sensing signal correction circuit configured to reduce the offset in the current sensing signal received by the overcurrent protection circuit during a switching transient period; and

a Kelvin emitter resistor electrically connected to a first emitter terminal of the first switching device,

wherein the current sensing signal correction circuit is electrically connected with the Kelvin emitter resistor in parallel.

2. The driving circuit of claim 1, wherein the current sensing signal correction circuit includes an inductor, the inductor and the Kelvin emitter resistor forming a filter circuit.

3. The driving circuit of claim 2, wherein a time constant of the filter circuit is longer than a switching oscillatory current damping period.

4. The driving circuit of claim 3, wherein the Kelvin emitter resistor is configured to attenuate an oscillatory current during the switching oscillatory current damping period.

5. The driving circuit of claim 2, wherein a time constant of the filter circuit is shorter than a response time of the overcurrent protection circuit.

6. The driving circuit of claim 2, wherein:

the overcurrent protection circuit is configured to compare the current sensing signal with a predetermined threshold; and

the inductor is configured to short-circuit the Kelvin emitter resistor when the overcurrent protection circuit compares the current sensing signal with the predetermined threshold.

7. The driving circuit of claim 1, wherein the switching transient period includes a turning on period of the first switching device.

8. The driving circuit of claim 1, wherein the first and second switching devices are insulated-gate bipolar transistors (IGBTs).

9. The driving circuit of claim 1, wherein

the first switching device includes a first collector terminal, the first emitter terminal, a current sensing terminal, and a first gate terminal;

and

the second switching device includes a second collector terminal, a second emitter terminal, and a second gate terminal,

wherein;

the first and second collector terminals are electrically connected;

the first and second gate terminals are electrically connected to a gate command terminal of the driver circuit;

the first and second emitter terminals are electrically connected; and

the current sensing terminal is electrically connected with the current sensing circuit.

10. A method for driving a load, comprising:

electrically connecting first and second switching devices in parallel;

generating, by a current sensing circuit, a current sensing signal indicating a value of a current flowing through the first switching device, the current sensing signal including an offset caused by parasitic inductance imbalance in electrical connections connecting the first and second switching devices;

reducing, by a current sensing signal correction circuit, the offset in the current sensing signal during a switching transient period;

receiving, by an overcurrent protection circuit of a driver circuit, the current sensing signal having the reduced offset for protecting the first switching device from overcurrent;

electrically connecting a Kelvin emitter resistor to an emitter terminal of the first switching device; and

electrically connecting the current sensing signal correction circuit with the Kelvin emitter resistor in parallel.

11. The method of claim 10, wherein the current sensing signal correction circuit includes an inductor, and the method further comprises:

forming a filter circuit using the inductor and the Kelvin emitter resistor.

12. The method of claim 11, further comprising:

setting a time constant of the filter circuit to be longer than a switching oscillatory current damping period.

13. The method of claim 11, further comprising:

setting a time constant of the filter circuit to be shorter than a response time of the overcurrent protection circuit.

14. The method of claim 11, further comprising:

comparing, by the overcurrent protection circuit, the current sensing signal with a predetermined threshold; and

short-circuiting the Kelvin emitter resistor using the inductor when the overcurrent protection circuit compares the current sensing signal with the predetermined threshold.

15. An inverter for driving a motor of an electric vehicle, comprising:

first and second insulated-gate bipolar transistor (IGBT) switches electrically connected with each other in parallel;

a current sensing circuit configured to generate a current sensing signal indicating a value of a current flowing through the first IGBT switch, the current sensing signal including an offset caused by parasitic inductance imbalance in electrical connections connecting the first and second IGBT switches;

a driver circuit electrically connected to the first and second IGBT switches and configured to control switching operations of the first and second IGBT switches, the driver circuit including an overcurrent protection circuit electrically connected to the current sensing circuit for receiving the current sensing signal;

a current sensing signal correction circuit configured to reduce the offset in the current sensing signal received by the overcurrent protection circuit during a switching transient period; and

a Kelvin emitter resistor electrically connected to an emitter terminal of the first IGBT switch,

wherein the current sensing signal correction circuit is electrically connected with the Kelvin emitter resistor in parallel.

16. The inverter of claim 15, wherein current sensing signal correction circuit includes an inductor electrically connected in parallel with the Kelvin emitter resistor.

17. The inverter of claim 16, wherein a time constant of a filter circuit including the inductor and the Kelvin emitter resistor is longer than a switching oscillatory current damping period and shorter than a response time of the overcurrent protection circuit.