Short circuit protection for bidirectional switches

Abstract

A bidirectional switch fault protection circuit includes a bidirectional switch circuit, a desaturation detection circuit, and a gate driver. The bidirectional switch circuit generates first and second switch voltages based on a direction of current. The desaturation detection circuit outputs the first switch voltage in response to current flowing in a first direction and outputs the second switch voltage in response to current flowing in a second direction opposite the first direction. The gate driver receives the first switch voltage in response to current flowing in the first direction and receives the second switch voltage in response to current flowing in the second direction. The gate driver detects a first short condition based on the first switch voltage and detects a second short condition based on the second switch voltage.

Description

Technical Field

[0001] This subject matter generally relates to motor vehicles, and more specifically to the detection of bidirectional fault currents in motor vehicles. Background Technology

[0002] Some types of vehicles consist solely of an internal combustion engine that generates propulsive torque. Electric vehicles typically employ one or more electric motors, which are used for propulsion. One or more power circuits within the vehicle supply battery power to a given electric motor.

[0003] Hybrid vehicles consist of an internal combustion engine and one or more electric motors. Some types of hybrid vehicles utilize both electric motors and an internal combustion engine in an effort to achieve higher fuel efficiency than using only the internal combustion engine. Certain types of hybrid vehicles also utilize both electric motors and an internal combustion engine to achieve greater torque output than the internal combustion engine alone can provide.

[0004] Some examples of hybrid vehicle types include parallel hybrid vehicles, series hybrid vehicles, and other types. In a parallel hybrid vehicle, the electric motor works in parallel with the engine, combining the power and range advantages of the engine with the efficiency and regenerative braking advantages of the electric motor. In a series hybrid vehicle, the engine drives a generator motor to generate electricity for the electric motor, which in turn drives the transmission. This allows the electric motor to take on some of the engine's power responsibilities, thus allowing for the use of a smaller and potentially more efficient engine. Summary of the Invention

[0005] In one exemplary embodiment, the bidirectional switch fault protection circuit includes a bidirectional switch circuit configured to generate a first switching voltage in response to receiving a current flowing in a first direction, and to generate a second switching voltage in response to receiving a current flowing in a second direction opposite to the first direction. A desaturation detection circuit is electrically connected to the bidirectional switch circuit. The desaturation detection circuit is configured to output the first switching voltage in response to a current flowing in the first direction, and to output the second switching voltage in response to a current flowing in the second direction. A gate driver is electrically connected to the desaturation detection circuit. The gate driver is configured to receive the first switching voltage in response to a current flowing in the first direction, and to receive the second switching voltage in response to a current flowing in the second direction. The gate driver is configured to detect a first short-circuit condition based on the first switching voltage, and to detect a second short-circuit condition based on the second switching voltage.

[0006] In addition to one or more features described herein, the gate driver is configured to compare the first switching voltage with a short-circuit voltage threshold in response to current flowing in the first direction, and to detect the first short-circuit condition in response to the first switching voltage exceeding the short-circuit voltage threshold; and is configured to compare the second switching voltage with the short-circuit voltage threshold in response to current flowing in the second direction, and to detect the second short-circuit condition in response to the second switching voltage exceeding the short-circuit voltage threshold.

[0007] In addition to one or more of the features described herein, the short-circuit voltage threshold has a negative value.

[0008] In addition to one or more features described herein, the gate driver also includes an output electrically connected to a bidirectional switching circuit. The gate driver is configured to cut off one or both of the first and second switching voltages in response to the detection of one or both of a first short-circuit condition and a second short-circuit condition.

[0009] In addition to one or more features described herein, the bidirectional switching circuit includes a first power semiconductor switch configured to generate a first switching voltage and a second power semiconductor switch configured to generate a second switching voltage.

[0010] In addition to one or more features described herein, the gate driver is configured to turn off one or both of the first power semiconductor switch and the second power semiconductor switch in response to detecting one or both of the first short-circuit condition and the second short-circuit condition.

[0011] In addition to one or more features described herein, the gate driver includes a desaturation input. The desaturation input is electrically connected to a first power semiconductor switch to receive a first switching voltage having a negative voltage value, and is electrically connected to a second power semiconductor switch to receive a second switching voltage having a negative voltage value.

[0012] In another exemplary embodiment, the bidirectional switch fault protection circuit includes a bidirectional switch circuit configured to generate a first switching voltage in response to receiving a current flowing in a first direction, and to generate a second switching voltage in response to receiving a current flowing in a second direction opposite to the first direction. A desaturation detection circuit is electrically connected to the bidirectional switch circuit. The desaturation detection circuit is configured to output the first switching voltage in response to a current flowing in the first direction, and to output the second switching voltage in response to a current flowing in the second direction. A gate driver is electrically connected to the desaturation detection circuit. The gate driver includes a first desaturation input configured to receive the first switching voltage in response to a current flowing in the first direction, and a second desaturation input configured to receive the second switching voltage in response to a current flowing in the second direction.

[0013] In addition to one or more features described herein, the gate driver is configured to detect a first short-circuit condition based on the first switching voltage received at the first desaturation input and to detect a second short-circuit condition based on the second switching voltage received at the second desaturation input.

[0014] In addition to one or more features described herein, the gate driver is configured to compare the first switching voltage received at the first desaturation input with a first short-circuit voltage threshold, and to compare the second switching voltage received at the second desaturation input with a second short-circuit voltage threshold. The gate driver is also configured to detect a first short-circuit condition in response to the first switching voltage exceeding the first short-circuit voltage threshold, and to detect a second short-circuit condition in response to the second switching voltage exceeding the second short-circuit voltage threshold.

[0015] In addition to one or more features described herein, both the first short-circuit voltage threshold and the second short-circuit voltage threshold have positive values.

[0016] In addition to one or more features described herein, the bidirectional switching circuit includes a first power semiconductor switch configured to generate a first switching voltage and a second power semiconductor switch configured to generate a second switching voltage.

[0017] In addition to one or more features described herein, the gate driver is configured to turn off one or both of the first power semiconductor switch and the second power semiconductor switch in response to detecting one or both of the first short-circuit condition and the second short-circuit condition.

[0018] In addition to one or more features described herein, the gate driver includes a first output electrically connected to a first power semiconductor switch and a second output electrically connected to a second power semiconductor switch. The gate driver is also configured to turn off the first power semiconductor switch in response to the detection of a first short-circuit condition and to turn off the second power semiconductor switch in response to the detection of a second short-circuit condition.

[0019] In another exemplary embodiment, the bidirectional switch fault protection circuit includes a bidirectional switch circuit configured to generate a first switching voltage in response to receiving a current flowing in a first direction, and to generate a second switching voltage in response to receiving a current flowing in a second direction opposite to the first direction. A desaturation detection circuit is electrically connected to the bidirectional switch circuit. The desaturation detection circuit is configured to output the first switching voltage in response to the current flowing in the first direction, and to output the second switching voltage in response to the current flowing in the second direction. A first gate driver and a second gate driver are electrically connected to the desaturation detection circuit. The first gate driver is configured to receive the first switching voltage in response to the current flowing in the first direction. The second gate driver is configured to receive the second switching voltage in response to the current flowing in the second direction.

[0020] In addition to one or more features described herein, the first gate driver is configured to detect a first short-circuit condition based on a first switching voltage, and the second gate driver is configured to detect a second short-circuit condition based on a second switching voltage.

[0021] In addition to one or more features described herein, the first gate driver is configured to compare the first switching voltage with a first short-circuit voltage threshold and detect the first short-circuit condition in response to the first switching voltage exceeding the first short-circuit voltage threshold. The second gate driver is configured to compare a second switching voltage with a second short-circuit voltage threshold and detect a second short-circuit condition in response to the second switching voltage exceeding the second short-circuit voltage threshold.

[0022] In addition to one or more features described herein, both the first short-circuit voltage threshold and the second short-circuit voltage threshold have positive values.

[0023] In addition to one or more features described herein, the bidirectional switching circuit includes a first power semiconductor switch and a second power semiconductor switch. The first power semiconductor switch is configured to generate a first switching voltage. The second power semiconductor switch is configured to generate a second switching voltage.

[0024] In addition to one or more features described herein, the first gate driver is configured to turn off the first power semiconductor switch in response to detecting a first short-circuit condition, and the second gate driver is configured to turn off the second power semiconductor switch in response to detecting a second short-circuit condition.

[0025] The above-described features and advantages, as well as other features and advantages, of this disclosure will become apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0026] Other features, advantages, and details appear by way of example only in the following detailed description, which is described in detail with reference to the accompanying drawings, in which:

[0027] Figure 1 A motor vehicle according to a non-limiting embodiment disclosed in this subject matter is shown;

[0028] Figure 2 This is a schematic diagram of a bidirectional switch fault protection circuit according to a non-limiting embodiment disclosed in this subject matter;

[0029] Figure 3 This illustrates a non-limiting embodiment disclosed in this subject matter. Figure 2 The diagram shows the operation of the bidirectional switch fault protection circuit.

[0030] Figure 4 This illustrates a non-limiting embodiment disclosed in this subject matter. Figure 2 The diagram shows the operation of the bidirectional switch fault protection circuit.

[0031] Figure 5 This is a schematic diagram of a bidirectional switch fault protection circuit according to another non-limiting embodiment disclosed in this subject matter; and

[0032] Figure 6 This is a schematic diagram of a bidirectional switch fault protection circuit according to another non-limiting embodiment disclosed in this subject matter. Detailed Implementation

[0033] The following description is exemplary in nature only and is not intended to limit this disclosure, its application, or use. It should be understood that in all the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0034] Motor vehicles utilize alternating current (AC) power supplied from a direct current (DC) source, such as a battery. In some power systems, a gate driver is implemented to control the operation of a bidirectional switching circuit, which includes a pair of opposing power semiconductor switches configured to perform bidirectional voltage blocking. Power semiconductor switches include, but are not limited to, insulated-gate bipolar transistors (IGBTs), junction field-effect transistors (JFETs), and metal-oxide-semiconductor field-effect transistors (MOSFETs), which can be wide-bandgap or ultra-wide-bandgap. Power semiconductor switches can be used to construct a variety of power devices or circuits, including but not limited to inverters, converters, relays, and fuses.

[0035] According to a non-limiting embodiment disclosed in this subject matter, a bidirectional switch fault protection circuit includes a desaturation detection circuit that connects the bidirectional switch circuit to one or more gate drivers configured to provide desaturation, bidirectional short-circuit, or overcurrent protection. The one or more gate drivers included in the bidirectional switch fault protection circuit are configured to perform desaturation voltage-based protection on the bidirectional switch circuit in response to the detection of a short-circuit current flowing in the positive or negative direction.

[0036] refer to Figure 1 The vehicle 10 includes a body 14. The vehicle 10 also includes a plurality of wheels 18 that rotatably support the body 14 on the ground (i.e., a surface on which the vehicle is parked or travels). The vehicle 10 also includes a powertrain 20, which includes an electric motor 22. The electric motor 22 is operatively connected to at least one of the wheels 18 to transmit torque to it and thereby propel the vehicle 10. The electric motor 22 can be connected directly or indirectly to the wheels 18 via a transmission system, such as a multi-speed transmission. The powertrain 20 also includes a power source, such as a battery 26, which provides electrical energy to the electric motor 22.

[0037] In the depicted non-limiting embodiment, powertrain 20 is a battery-electric powertrain (i.e., battery 26 is the sole energy source for powering electric motor 22). However, other powertrain configurations with electric motors may be employed within the scope of the embodiments described herein. For example, the powertrain could also be a hybrid electric powertrain, wherein an engine also provides power to propel the vehicle in series or parallel with electric motor 22, or drives a generator motor source to produce AC or DC electricity, which may be coupled to electric motor 22.

[0038] According to a non-limiting embodiment, the electric motor 22 may be a permanent magnet electric motor using AC power. The battery 26 provides DC power. The power system 20 includes one or more power circuits 30 operatively connected to the battery 26. In at least one non-limiting embodiment, the power circuit 30 includes, but is not limited to, solid-state relays, inverters, and converters. The solid-state relays selectively connect and disconnect the battery 26 and may operate as isolating contactors and fuses. The inverter may include a DC-to-AC inverter operatively connected to the electric motor 22. The inverter is configured to receive DC power from the battery 26, convert it to AC power, and deliver the converted AC power to the electric motor. The converter may include, but is not limited to, a DC-DC converter configured to receive a DC voltage having a first voltage level and output a DC voltage having a second voltage level higher or lower than the first voltage level.

[0039] The power system 20 also includes a controller 34 operatively connected to the electric motor 22 and one or more power supply circuits 30, such that the controller 34 controls the electric motor 22 and the given power supply circuits 30. The controller 34 may be a general-purpose digital computer, typically including a microprocessor or central processing unit, one or more forms of memory, clock and synchronization circuitry, analog-to-digital (A / D) and digital-to-analog (D / A) circuitry, input / output circuitry and devices (I / O), and appropriate signal conditioning and buffering circuitry. The controller 34 may have a set of control algorithms, including resident program instructions and calibrations stored in memory and executed to provide the corresponding functions of the controller 34. As used herein, "controller" may include one or more controllers, microprocessors, central processing units, memory units, and / or other devices that cooperate to perform the operations described herein.

[0040] Vehicle 10 also includes an input device 38 operable by the driver of vehicle 10 to input a desired or requested torque output of electric motor 22. In a non-limiting embodiment shown, input device 38 includes a foot pedal 42 that can be selectively pressed. Input device 38 also includes a sensor 46 that determines the position of pedal 42 and transmits a signal indicating the position of pedal 42 to controller 34. Typically, a larger displacement of the pedal from its default position indicates a higher torque demand. When pedal 42 is not pressed, the requested torque is zero. Controller 34, in response to the position of pedal 42, controls the torque output of electric motor 22 by adjusting the amount of energy transferred from battery 26 to electric motor 22 via power circuit 30 (e.g., inverter). Input device 38 may also include the output of an autonomous vehicle operation controller 36 that can control the vehicle to operate autonomously according to one or more vehicle operations described herein.

[0041] Turn now Figure 2 A bidirectional switch fault protection circuit 100 according to a non-limiting embodiment is shown. The bidirectional switch fault protection circuit 100 includes a power supply 102, a bidirectional switch circuit 200, a gate driver 300, and a desaturation detection circuit 400. The power supply 102 is used to output current. The current can be generated as alternating current (AC) or direct current (DC) and periodically reverses direction between a first direction or positive direction (e.g., from positive voltage potential to negative voltage potential) and an opposite second direction or negative direction (e.g., from negative voltage potential to positive voltage potential), and its magnitude continuously changes over time, as understood by those skilled in the art.

[0042] The bidirectional switching circuit 200 is electrically connected to a power source to receive current. The bidirectional switching circuit 200 can be implemented in various electronic devices or systems, including but not limited to power converters or power inverters. For example, the bidirectional switching circuit 200 can be connected to the battery 26 and included in... Figure 1Between the inverters in the power supply circuit 30 shown.

[0043] The bidirectional switching circuit 200 includes a first power semiconductor switch 202 and a second power semiconductor switch 204. The first power semiconductor switch 202 and the second power semiconductor switch 204 can be connected in series back-to-back to establish a bidirectional switch configured to perform four-quadrant switching operation. That is, as understood by those skilled in the art, the first power semiconductor switch 202 and the second power semiconductor switch 204 operate together to allow current conduction and block voltages of both polarities. As described herein, the first power semiconductor switch 202 and the second power semiconductor switch 204 can be implemented as a first MOSFET 202 and a second MOSFET 204, respectively. The first and second MOSFETs 202 and 204 can be constructed using semiconductor materials including, but not limited to, silicon (Si), diamond, silicon carbide (SiC), gallium nitride (GaN), and boron nitride (BN). Although MOSFETs 202 and 204 are described herein, it should be understood that other types of power semiconductor switches, such as insulated-gate bipolar transistors (IGBTs) used in conjunction with corresponding diodes, or IGBTs or bipolar junction transistors (BJTs) used in conjunction with corresponding diodes, can be used without departing from the scope of this disclosure.

[0044] The first MOSFET 202 includes a first drain terminal and a first source terminal. The first drain terminal is connected to the positive terminal (+) of the power supply 102. The voltage between the first drain terminal (Vdrain1) and the first source terminal defines a first switching voltage (Vds1). The second MOSFET 204 includes a second drain terminal and a second source terminal. The second source terminal of the second MOSFET 204 is directly connected to the first source terminal of the first MOSFET 202, thereby establishing a source node 206. The second drain terminal (Vdrain2) of the second MOSFET 204 is connected to the negative terminal (-) of the power supply 102 via a load 208. In one or more non-limiting embodiments, the load 208 is an inverter-motor system included in the vehicle 10. The voltage between the second drain terminal (Vdrain2) and the second source terminal defines a second switching voltage (Vds2).

[0045] Each of the first MOSFET 202 and the second MOSFET 204 also includes a gate configured to receive corresponding control signals 210 and 212 from the gate driver 300. Although the first MOSFET 202 and the second MOSFET 204 are shown to receive two independent control signals 210 and 212, it should be understood that in other examples, the gates of the first MOSFET 202 and the second MOSFET 204 may receive a single control signal.

[0046] Control signals 210 and 212 are configured to control the operation of the first MOSFET 202 and the second MOSFET 204. For example, control signals 210 and 212 can continuously turn the first MOSFET 202 and the second MOSFET 204 on and off according to a target switching frequency. Furthermore, the gate driver 300 is configured to deactivate one or both of the first MOSFET 202 and the second MOSFET 204 (i.e., keep a given MOSFET in an off-switch state) in response to the detection of at least one short-circuit condition as described herein.

[0047] The gate driver 300 is connected to the bidirectional switching circuit 200 and the desaturation detection circuit 400. Figure 2 In the example shown, the desaturation detection circuit 400 selectively delivers a first switching voltage associated with the first MOSFET 202 or a second switching voltage associated with the second MOSFET 204 based on the direction of the current flowing through the bidirectional switching circuit 200. Therefore, the gate driver 300 can detect a short circuit based on either the first or second switching voltage.

[0048] According to at least one non-limiting embodiment of this disclosure, the gate driver 300 includes a source input (Vsource_IN) 302 and a desaturation input (DSAT) 304. The source input (Vsource_IN) 302 is connected to a source node 206 to receive a source voltage present at the source node 206. The desaturation input (DSAT) 304 is configured to receive a first switching voltage associated with a first MOSFET 202 and a second switching voltage associated with a second MOSFET 204. Diodes 402 and 404 are arranged to selectively transmit the lower of the first switching voltage (Vdrain1-Vsource) or the second switching voltage (Vdrain2-Vsource). Figure 2 In either of the cases shown in the examples, the first switching voltage and the second switching voltage have negative voltage values.

[0049] A fault indicated by a first or second switching voltage is handled by the gate driver 300 based on one or more short-circuit thresholds associated with the gate driver 300. For example, the first or second switching voltage received at the desaturation input (DSAT) 304 is compared with the source voltage received at the source input (Vsource_IN) 302 to determine a differential voltage, which is then compared with a short-circuit threshold voltage. Figure 2 In the non-limiting embodiment shown, the lower of the first or second switching voltage received at the desaturation input (DSAT) 304 is a negative voltage value. Therefore, the short-circuit threshold voltage used by the gate driver 300 is set to a negative value.

[0050] According to a non-limiting embodiment of this disclosure, when current flows through the bidirectional switching circuit 200 in a first direction (e.g., from the positive power supply terminal (+) to the negative power supply terminal (-)), the desaturation input (DSAT) 304 receives a second switching voltage generated by the second MOSFET 204. However, when current flows through the bidirectional switching circuit in a second direction (e.g., from the negative power supply terminal (-) to the positive power supply terminal (+)), the desaturation input (DSAT) 304 receives a first switching voltage generated by the first MOSFET 202. Therefore, depending on the current direction, a single desaturation input (DSAT) 304 can be used to receive either the first or the second switching voltage. In this way, a desaturation detection circuit 400 capable of providing desaturation and bidirectional short-circuit protection can be implemented, while reducing the components and signal connections required to facilitate bidirectional short-circuit detection.

[0051] The gate driver 300 also has an internal reference voltage that serves as a short-circuit threshold voltage. Figure 2 In the example shown, the internal reference voltage is negative. However, in other examples, the internal threshold reference voltage can be set to a positive threshold reference voltage. Therefore, the gate driver 300 is configured to compare a first switching voltage or a second switching voltage with the threshold reference voltage and detect a short-circuit event in response to at least one of the first or second switching voltages being more negative than the threshold reference voltage. In this way, the gate driver 300 can provide desaturation and bidirectional short-circuit protection for the bidirectional switching circuit 200 in response to the detection of a short circuit.

[0052] For example, gate driver 300 includes a first output that communicates with a first MOSFET 202 to transmit a first control signal 210, and a second output that communicates with a second MOSFET 204 to transmit a second control signal 212 independently of the first control signal 210. The first and second control signals 210 and 212 allow gate driver 300 to control the first MOSFET 202 and the second MOSFET 204. According to at least one non-limiting embodiment of the present disclosure, gate driver 300 is configured to turn off one or both of the first and second switching voltages by turning off (i.e., deactivating) one or both of the first MOSFET 202 and the second MOSFET 204 in response to the detection of at least one of a plurality of short-circuit conditions. The plurality of short-circuit conditions include, for example, a first short-circuit condition defined by current flowing through bidirectional switching circuit 200 in a first direction (e.g., from power supply positive terminal (+) to power supply negative terminal (-)), and a second short-circuit condition defined by current flowing through bidirectional switching circuit 200 in a second direction (e.g., from power supply negative terminal (-) to power supply positive terminal (+)).

[0053] The desaturation detection circuit 400 includes a first desaturation diode 402, a second desaturation diode 404, a desaturation resistor 406, and a desaturation capacitor 408. The first desaturation diode 402 includes a first cathode connected to the first drain terminal of a first MOSFET 202 and a first anode connected to the desaturation resistor 406. The second desaturation diode 404 includes a second cathode connected to the second drain terminal of the load 208 and the second MOSFET 204. The anode of the second desaturation diode 404 is connected to the first anode of the first desaturation diode 402 and the desaturation resistor 406.

[0054] The desaturation resistor 406 includes a first terminal connected to the desaturation input (DSAT) 304 of the gate driver 300. The second terminal desaturation resistor 406 is connected to the first anode of the first desaturation diode 402 and the second anode of the second desaturation diode 404. The desaturation resistor 406 fine-tunes either the first or second switching voltage and transmits the fine-tuned switching voltage to the desaturation capacitor 408. Therefore, the desaturation resistor 406 can be used to dynamically set the compatibility between the first and second MOSFETs 202, 204 and the gate driver 300 by adjusting the voltage appearing at the desaturation input (DSAT) 304, rather than replacing the entire gate driver 300 with different gate drivers having internal thresholds compatible with the first and second MOSFETs 202 and 204.

[0055] The value of the desaturation resistor 406 also sets the resistance used in conjunction with the gate driver 300. The resistance value can be selected by implementing a resistor with a specific resistance for the application of the bidirectional switch fault protection circuit 100, or it can be implemented as a variable resistor whose resistance can be dynamically adjusted or preset by design. In either case, the selected resistance of the desaturation resistor 406 can be used to set the voltage appearing at the desaturation input (DSAT) 304 to a target positive or target negative value, which can be used for each application without change.

[0056] The desaturation capacitor 408 includes a first terminal connected to the source node 206 and the gate driver source input (Vsource_IN) 302. The opposite second terminal is connected to the first terminal of the desaturation resistor 406 and the gate driver desaturation input (DSAT) 304. A fault, indicated by a first or second switching voltage, occurs across capacitor 408 and is input to the gate driver 300 via the desaturation input (DSAT) 304. The desaturation capacitor 408 also operates to provide a blanking time when the first and second MOSFETs 202 and 204 are turned on, preventing false short-circuit detection caused by high switching voltages or transients.

[0057] As described herein, the desaturation detection circuit 400 provides a first or second switching voltage to the gate driver 300 based on the direction of the current flowing through the bidirectional switching circuit 200. For example, when the current flows in the positive direction (i.e., from the positive power supply terminal (+) to the negative power supply terminal (-)) (see... Figure 3 The loop operation includes the second desaturation diode 404 to deliver the second switching voltage to the desaturation input (DSAT) 304. However, when the current flows in the negative direction (i.e., from the negative power supply terminal (-) to the positive power supply terminal (+)) (see...) Figure 4 The first desaturation diode 402 operates to deliver the first switching voltage to the desaturation input (DSAT) 304.

[0058] In either case, the gate driver 300 compares the first switching voltage or the second switching voltage with a threshold reference voltage (e.g., a negative threshold reference voltage value in this example), and a short-circuit condition can be detected when either the first switching voltage or the second switching voltage reaches a voltage level exceeding the threshold reference voltage. If for Figure 2 , 3 The example embodiment shown in Figure 4 sets the threshold reference voltage to -2.5 volts (-2.5V). When either the first or second switching voltage reaches a level exceeding -2.5 volts (-2.5V), for example, if either the first or second switching voltage reaches a level of -3 volts (-3V), the gate driver 300 detects a short circuit. In response to the detection of the short circuit condition, the gate driver 300 can deactivate one or both of the first and second MOSFETs 202 and 204 as described herein. In this way, the gate driver 300 can perform protection of the bidirectional switching circuit based on the desaturation voltage in response to the detection of a positively or negatively flowing short-circuit current.

[0059] Now go to Figure 5 According to another non-limiting embodiment of this disclosure, a bidirectional switch fault protection circuit 100 is described. The bidirectional switch fault protection circuit 100 includes a power supply 102, a bidirectional switch circuit 200, a gate driver 300, and a desaturation detection circuit 400. The power supply 102 and the bidirectional switch circuit 200 operate in a similar manner to those described above. Therefore, for the sake of brevity, their operational details will not be repeated.

[0060] Gate driver 300 includes a source input 302 (Vsource_IN), a first desaturation input (DSAT1) 304, and a second desaturation input (DSAT2) 306. The source input (Vsource_IN) 302 is connected to source node 206 to receive the source voltage present at source node 206. Therefore, gate driver 300 includes dedicated desaturation inputs 304 and 306 configured to receive the first and second switching voltages, respectively, instead of a single desaturation input 304 configured to receive both the first and second switching voltages.

[0061] For example, the first desaturation input (DSAT1) 304 is configured to receive a first switching voltage associated with the first MOSFET 202 when current flows through the bidirectional switching circuit 200 in a first direction (e.g., from the positive power supply terminal (+) to the negative power supply terminal (-)). The second desaturation input (DSAT2) 306 is configured to receive a second switching voltage associated with the second MOSFET 204 when current flows through the bidirectional switching circuit 200 in a second direction (e.g., from the negative power supply terminal (-) to the positive power supply terminal (+)).

[0062] As described herein, the gate driver 300 also has an internal reference voltage that serves as a short-circuit threshold voltage. However, in this example, the threshold voltage is a positive value. Therefore, the gate driver 300 is configured to compare a first switching voltage and a second switching voltage with the threshold reference voltage, and to detect a short-circuit event in response to at least one of the first switching voltage or the second switching voltage exceeding (e.g., correcting) the threshold reference voltage.

[0063] The desaturation detection circuit 400 includes a first desaturation diode 402, a second desaturation diode 404, a first desaturation resistor 406, a second desaturation resistor 410, a first desaturation capacitor 408, and a second desaturation capacitor 412. The first desaturation diode 402 includes a first cathode connected to both the first drain terminal of the first MOSFET 202 and the positive terminal (+) of the power supply 102. The anode of the first desaturation diode 402 is connected to the first desaturation resistor 406. The second desaturation diode 404 includes a second cathode connected to both the load 208 and the second drain terminal of the second MOSFET 204. The anode of the second desaturation diode 404 is connected to the second desaturation resistor 410.

[0064] The first desaturation resistor 406 includes a first terminal connected to the first desaturation input (DSAT1) 304 and a second terminal directly connected to the anode of the first desaturation diode 402. The first desaturation resistor 406 is fine-tuned before the first switching voltage delivered by the first MOSFET 202 is delivered to the first desaturation capacitor 408. As described herein, the first resistance value can be selected by implementing a resistor with a resistance specific to the application of the bidirectional switch fault protection circuit 100, or it can be implemented as a variable resistor with dynamically adjustable resistance.

[0065] The second desaturation resistor 410 includes a first terminal connected to the second desaturation input (DSAT2) 306 and a second terminal directly connected to the anode of the second desaturation diode 404. The second desaturation resistor 410 fine-tunes the second switching voltage delivered by the second MOSFET 204 before it is delivered to the second desaturation capacitor 412. The second resistance value of the second desaturation resistor 410 also sets the resistance at the second desaturation input (DSAT2) 306 of the gate driver 300. As described herein, the second resistance value can be selected by implementing a resistor with a resistance specific to the application of the bidirectional switch fault protection circuit 100, or it can be implemented as a variable resistor with a dynamically adjustable resistance. In either case, the selected resistance of the second desaturation resistor 410 can be used to adjust the internal reference voltage of the gate driver 300 and set the second threshold reference voltage to a target positive value. By providing the first and second desaturation inputs 304 and 306, the first and second threshold reference voltages can be set independently of each other. According to at least one non-limiting embodiment of this disclosure, a first threshold reference voltage of the first gate driver 300 can be set to a first threshold, while a second threshold reference voltage of the second gate driver 350 can be set to a second threshold different from the first threshold. In this way, even if the first and second MOSFETs 202 and 204 are not identical, the short-circuit detection provided by the bidirectional switch fault protection circuit 100 can be precisely adjusted.

[0066] The first desaturation capacitor 408 includes a first terminal that is connected to the first desaturation input (DSAT1) 304 and the first desaturation resistor 406. The opposite second terminal of the first desaturation capacitor 408 is connected to the source node 206, the source input (Vsource_IN) 302, and the second desaturation capacitor 412. Therefore, a first switching voltage generated by the first MOSFET 202 appears across the first desaturation capacitor 408 and is input to the gate driver 300 via the first desaturation input (DSAT1) 304. The gate driver 300 then compares the first switching voltage received at the first desaturation input (DSAT1) 304 with the voltage appearing at the source input (Vsource_IN) 302 to detect an ongoing short circuit associated with the first MOSFET 202. The first desaturation capacitor 408 further operates to provide a blanking time such that a high switching voltage or transient associated with the first MOSFET 202 does not result in erroneous short circuit detection.

[0067] The second desaturation capacitor 412 includes a first terminal that is connected to the first terminal of the second desaturation input (DSAT2) 306 and the second desaturation resistor 410. The opposite second terminal of the desaturation capacitor 412 is connected to the second terminal of the source node 206, the source input (Vsource_IN) 302, and the first desaturation capacitor 408. A second switching voltage generated by the second MOSFET 204 appears across the second desaturation capacitor 412 and is input to the gate driver 300 via the second desaturation input (DSAT2) 306. Therefore, the gate driver 300 compares the second switching voltage received at the second desaturation input (DSAT2) 306 with the voltage appearing at the source input (Vsource_IN) 302 to detect an ongoing short-circuit fault associated with the second MOSFET 204. The second desaturation capacitor 412 further operates to provide a blanking time such that a high switching voltage or transient associated with the second MOSFET 204 does not result in erroneous short-circuit detection.

[0068] As described herein, the desaturation detection circuit 400 provides first and second switching voltages to the gate driver 300. The first switching voltage, generated by the first MOSFET 202, is positive when current flows in the positive direction and appears across the first desaturation capacitor 408 before being input to the first desaturation input (DSAT1) 304. Furthermore, the second switching voltage, generated by the second MOSFET 204, is negative and appears across the second desaturation capacitor 412 before being input to the second desaturation input (DSAT2) 306. In this example, the gate driver 300 uses the first switching voltage generated by the first MOSFET 202 to detect a short-circuit fault. No short-circuit fault is triggered at the second desaturation input (DSAT2) 306 because the short-circuit threshold is set to a positive threshold, and the short-circuit threshold is always higher than the second switching voltage when current flows in the negative direction through the bidirectional switching circuit 200.

[0069] When current flows in the negative direction through the bidirectional switching circuit 200, the second switching voltage generated by the second MOSFET 204 is positive, while the first switching voltage generated by the first MOSFET 202 is negative. Therefore, the gate driver 300 uses the second switching voltage generated by the second MOSFET 204 to detect short-circuit faults. In this example, no short-circuit fault is triggered at the first desaturation input (DSAT1) because the short-circuit threshold is set to a positive threshold, and when current flows in the negative direction through the bidirectional switching circuit 200, it is always higher than the negative first switching voltage.

[0070] Continue to refer to Figure 5 The gate driver 300 compares the first switching voltage with a first threshold reference voltage and compares the second switching voltage with a second threshold reference voltage (e.g., the positive threshold reference voltage value in this example). For Figure 5 In the example embodiment shown, if both the first and second threshold reference voltages are set to +2.5 volts (2.5V), then the gate driver 300 detects a short circuit when the first switching voltage reaches a level exceeding 2.5 volts (e.g., if the first switching voltage reaches a level exceeding +3 volts (3V)) or when the second switching voltage reaches a level exceeding 2.5 volts (e.g., if the second switching voltage reaches a level exceeding +3 volts (3V)). As described herein, in response to the detection of a short circuit, the gate driver 300 can deactivate one or both of the first and second MOSFETs 202 and 204. In this way, the gate driver 300 can perform protection of the bidirectional switching circuit based on desaturation voltage in response to the detection of a short-circuit current flowing in either the positive or negative direction.

[0071] Now for reference Figure 6According to another non-limiting embodiment of this disclosure, a bidirectional switch fault protection circuit 100 is described. The bidirectional switch fault protection circuit 100 includes a power supply 102, a bidirectional switch circuit 200, a first gate driver 300, a second gate driver 350, and a desaturation detection circuit 400. The power supply 102, the bidirectional switch circuit 200, and the desaturation detection circuit 400 operate in a similar manner to those described above. Therefore, for the sake of brevity, their operational details will not be repeated.

[0072] The first gate driver 300 communicates with the bidirectional switching circuit 200 and the desaturation detection circuit 400. The first gate driver 300 is configured to receive a first switching voltage generated by the first MOSFET 202. The second gate driver 350 also communicates with the bidirectional switching circuit 200 and the desaturation detection circuit 400, but is configured to receive a second switching voltage generated by the second MOSFET 204. Therefore, the first gate driver 300 detects a short-circuit fault condition based on the first switching voltage, while the second gate driver 350 detects a short-circuit fault condition based on the second switching voltage.

[0073] Continue to refer to Figure 6 In the example embodiment shown, the first gate driver 300 includes a first source input (Vsource_IN1) 302 and a first desaturation input (DSAT1) 304. The first source input (Vsource_IN1) 302 is connected to the source node 206 to receive the source voltage present at the source node 206.

[0074] The first desaturation input (DSAT1) 304 receives a positive switching voltage generated by the first MOSFET 202 in response to a current flowing through the bidirectional switching circuit 200 in a first direction (e.g., from the positive power supply terminal (+) to the negative power supply terminal (-)), and receives a negative switching voltage generated by the first MOSFET 202 in response to a current flowing through the bidirectional switching circuit 200 in a second direction (e.g., from the negative power supply terminal (-) to the positive power supply terminal (+)).

[0075] The first gate driver 300 also has a first internal reference voltage threshold, which serves as a first short-circuit threshold voltage and is positive in this example. Therefore, the first gate driver 300 is configured to compare a first switching voltage with its first internal reference voltage threshold and detect a short circuit in response to the first switching voltage exceeding (e.g., correcting) the first internal reference voltage threshold. However, when current flows through the bidirectional switching circuit 200 in a second direction (e.g., from the negative power supply terminal (-) to the positive power supply terminal (+)) and receives a negative switching voltage generated by the first MOSFET 202, a short-circuit fault is not triggered at the first desaturation input (DSAT1) because the first internal reference voltage threshold is set to a positive threshold and is always higher than the negative first switching voltage generated when current flows through the bidirectional switching circuit 200 in the negative direction.

[0076] Continue to refer to Figure 6 The second gate driver 350 includes a second source input (Vsource_IN2) 308 and a second desaturation input (DSAT2) 310. The second source input (Vsource_IN2) 308 is also connected to the second source node 206 to receive the source voltage present at the source node 206. Therefore, the first and second gate drivers 300 and 350 receive a common source voltage present at the source node 206. The second desaturation input (DSAT2) 310 receives a positive switching voltage generated by the second MOSFET 204 in response to current flowing through the bidirectional switching circuit 200 in a second direction (e.g., in the negative direction from the positive power supply terminal (-) to the negative power supply terminal (+)), and receives a negative switching voltage generated by the second MOSFET 204 in response to current flowing through the bidirectional switching circuit 200 in a first direction (e.g., in the positive direction from the positive power supply terminal (+) to the negative power supply terminal (-)).

[0077] The second gate driver 350 also has a second internal reference voltage threshold, which serves as a second short-circuit voltage threshold and is positive in this example. The second gate driver 350 is configured to compare the positive switching voltage generated by the second MOSFET 204 with its internal reference voltage threshold in response to current flowing in the negative direction through the bidirectional switching circuit 200, and to detect a short circuit in response to the second switching voltage exceeding (e.g., correcting) its second internal reference voltage threshold. However, when current flows in the positive direction through the bidirectional switching circuit 200, the second desaturation input (DSAT2) 310 receives the negative switching voltage generated by the second MOSFET 204. As a result, a short-circuit fault is not triggered at the second desaturation input (DSAT2) 310 because the positive value of the gate driver's internal reference voltage threshold is always higher than the negative switching voltage generated by the second MOSFET 204 when current flows in the positive direction through the bidirectional switching circuit 200.

[0078] Both the first gate driver 300 and the second gate driver 350 are configured to control the first and second MOSFETs 202 and 204 in response to the detection of a fault condition (e.g., a short-circuit condition). For example, the first gate driver 300 includes a first output in signal communication with the first MOSFET 202 to transmit a first control signal 210. Therefore, the first gate driver 300 is configured to turn off (i.e., deactivate) the first MOSFET 202 in response to the detection of a short circuit. Similarly, the second gate driver 350 also includes a second output in signal communication with the second MOSFET 204 to transmit a second control signal 212. Therefore, the second gate driver 350 is configured to turn off (i.e., deactivate) the second MOSFET 204 in response to the detection of a short-circuit fault. In this way, the gate drivers 300 and 350 can perform protection of the bidirectional switching circuit based on desaturation voltage in response to the detection of a short-circuit current flowing in either the positive or negative direction.

[0079] As described herein, various non-limiting embodiments disclosed in this subject matter provide a bidirectional switch fault protection circuit including a desaturation detection circuit that facilitates electrical connection between a bidirectional switch circuit and one or more gate drivers configured to provide desaturation, bidirectional short-circuit, or overcurrent protection. The one or more gate drivers included in the bidirectional switch fault protection circuit are configured to perform desaturation voltage-based protection on the bidirectional switch circuit in response to the detection of a short-circuit current flowing in either the positive or negative direction.

[0080] While the above disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made thereto and equivalent substitutions can be made to its elements without departing from its scope. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this disclosure without departing from its essential scope. Therefore, it is intended that this disclosure be limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A bidirectional switch fault protection circuit, comprising: a bidirectional switch circuit configured to produce a first switch voltage in response to receiving a current flowing in a first direction and a second switch voltage in response to receiving a current flowing in a second direction opposite the first direction; a desaturation circuit electrically connected to the bidirectional switch circuit, the desaturation circuit configured to output the first switch voltage in response to the current flowing in the first direction and the second switch voltage in response to the current flowing in the second direction; and a gate driver electrically connected to the desaturation circuit, the gate driver configured to receive the first switch voltage in response to the current flowing in the first direction and the second switch voltage in response to the current flowing in the second direction, and configured to detect a first short condition based on the first switch voltage and a second short condition based on the second switch voltage.

2. The bidirectional switch fault protection circuit of claim 1, wherein, the gate driver configured to compare the first switch voltage to a short voltage threshold in response to the current flowing in the first direction, and to detect the first short condition in response to the first switch voltage exceeding the short voltage threshold; and wherein the gate driver is configured to compare the second switch voltage to the short voltage threshold in response to the current flowing in the second direction, and to detect the second short condition in response to the second switch voltage exceeding the short voltage threshold.

3. The bidirectional switch fault protection circuit of claim 2, wherein, the short voltage threshold has a negative value.

4. A bidirectional switch fault protection circuit, comprising: a bidirectional switch circuit configured to produce a first switch voltage in response to receiving a current flowing in a first direction and a second switch voltage in response to receiving a current flowing in a second direction opposite the first direction; a desaturation circuit electrically connected to the bidirectional switch circuit, the desaturation circuit configured to output the first switch voltage in response to the current flowing in the first direction and the second switch voltage in response to the current flowing in the second direction; and a gate driver electrically connected to the desaturation circuit, the gate driver including a first desaturation input configured to receive the first switch voltage in response to the current flowing in the first direction, and including a second desaturation input configured to receive the second switch voltage in response to the current flowing in the second direction.

5. The bidirectional switch fault protection circuit of claim 4, wherein, the gate driver configured to detect a first short condition based on the first switch voltage received at the first desaturation input, and a second short condition based on the second switch voltage received at the second desaturation input.

6. The bidirectional switch fault protection circuit of claim 5, wherein, the gate driver configured to compare the first switch voltage received at the first desaturation input to a first short voltage threshold, and to compare the second switch voltage received at the second desaturation input to a second short voltage threshold, and wherein the gate driver is configured to detect the first short condition in response to the first switch voltage exceeding the first short voltage threshold, and to detect the second short condition in response to the second switch voltage exceeding the second short voltage threshold.

7. A bidirectional switch fault protection circuit, comprising: A bidirectional switching circuit configured to generate a first switching voltage in response to receiving a current flowing in a first direction, and to generate a second switching voltage in response to receiving a current flowing in a second direction opposite to the first direction. A desaturation circuit electrically connected to the bidirectional switching circuit is configured to output a first switching voltage in response to a current flowing in a first direction and a second switching voltage in response to a current flowing in a second direction. A first gate driver electrically connected to the desaturation circuit is configured to receive a first switching voltage in response to a current flowing in a first direction; and A second gate driver electrically connected to the desaturation circuit is configured to receive a second switching voltage in response to a current flowing in a second direction.

8. The bidirectional switch fault protection circuit of claim 7, wherein, The first gate driver is configured to detect a first short-circuit condition based on a first switching voltage, and the second gate driver is configured to detect a second short-circuit condition based on a second switching voltage.

9. The bidirectional switch fault protection circuit of claim 8, wherein, The first gate driver is configured to compare a first switching voltage with a first short-circuit voltage threshold, and is configured to detect a first short-circuit condition in response to the first switching voltage exceeding the first short-circuit voltage threshold. The second gate driver is configured to compare the second switching voltage with a second short-circuit voltage threshold and is configured to detect a second short-circuit condition in response to the second switching voltage exceeding the second short-circuit voltage threshold.

10. The bidirectional switch fault protection circuit of claim 9, wherein, The bidirectional switching circuit includes: A first power semiconductor switch, the first power semiconductor switch being configured to generate a first switching voltage; and A second power semiconductor switch, configured to generate a second switching voltage. The first gate driver is configured to turn off the first power semiconductor switch in response to detecting a first short-circuit condition, and the second gate driver is configured to turn off the second power semiconductor switch in response to detecting a second short-circuit condition.

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