Gate drive circuit fault detection techniques

Abstract

The invention relates to gate drive circuit fault detection techniques. A desaturation detection circuit is described that uses two or more desaturation circuit thresholds that convert a desaturation threshold in a normal mode of operation to a higher voltage when an active short circuit (ASC) signal is present in a faulty mode of operation. Included are two or more desaturation detection circuit thresholds allowing a lower desaturation threshold in a normal mode of operation and a higher voltage in a failure mode of operation or mode dependent threshold selection.

Description

Technical Field

[0001] This document generally relates to, but is not limited to, fault detection in power transistors. Background Art

[0002] In the field of power electronics, efficiently managing electrical energy is the cornerstone of numerous applications, from renewable energy systems to industrial automation and consumer electronics. At the heart of these systems are power switches, such as insulated gate bipolar transistors (IGBTs) and field-effect transistors (FETs), which play a vital role in controlling the flow of electrical energy. These components enable efficient and precise conversion, distribution, and regulation of electrical power.

[0003] Power switches face various operational challenges that can impact their performance and lifetime. One such challenge is managing desaturation events, an example of an overcurrent event. Such events can cause excessive power dissipation and potentially damage the power switch itself. The ability to effectively manage these events is crucial to maintaining the reliability and safety of power electronics systems.

[0004] Gate driver circuits are an integral part of power switch operation, providing the necessary drive voltage to control switching between the conductive (on) and non-conductive (off) states. In addition to basic control functions, gate driver circuits are increasingly incorporating advanced protection features designed to detect and respond to fault conditions to prevent damage to the power switch and ensure continued safe operation of the overall system. Summary of the Invention

[0005] The present invention describes a desaturation detection circuit that uses two or more desaturation circuit thresholds to shift the desaturation threshold in normal operation mode to a higher voltage when the ASC signal is present in the fault operation mode. Including two or more desaturation detection circuit thresholds allows for a lower desaturation threshold in normal operation mode and a higher voltage in the fault operation mode or in a mode-dependent threshold selection.

[0006] In some aspects, the present disclosure is directed to a gate driver circuit for driving a transistor, the gate driver circuit comprising: a current source coupled to a terminal of the transistor; and an overcurrent detection circuit comprising: a comparator configured to: receive a voltage representing an ON voltage across the transistor; compare the voltage with a threshold, wherein the threshold is selected from a plurality of thresholds; and generate an output signal when the voltage exceeds the threshold, wherein the output signal represents an overcurrent state of the transistor.

[0007] In some aspects, the present disclosure is directed to a method for dynamically adjusting a desaturation detection threshold in a gate driver circuit, the method comprising: providing a current to terminals of a transistor; receiving a voltage representing an ON voltage across the transistor; comparing the voltage to a threshold, wherein the threshold is selected from a plurality of thresholds; and generating an output signal when the voltage exceeds the threshold, wherein the output signal represents a desaturation event for the transistor.

[0008] In some aspects, the present disclosure is directed to a desaturation detection circuit comprising: a comparator configured to: receive a voltage representing an ON voltage across a transistor; compare the voltage to a threshold, wherein the threshold is selected from a plurality of thresholds; and generate an output signal when the voltage exceeds the threshold, wherein the output signal represents an overcurrent condition of the transistor; and a switch configured to select a threshold from the plurality of thresholds based on an operating mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In the accompanying drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals with different letter suffixes may represent different instances of similar components. The accompanying drawings generally illustrate various embodiments discussed in this document by way of example and not limitation.

[0010] Figure 1 is a simplified schematic diagram of an example of a current control system in which the various techniques of this disclosure may be implemented.

[0011] Figure 2 is a block diagram of an example of a gate driver circuit in which the various techniques of this disclosure may be implemented.

[0012] Figure 3 is a schematic diagram of an example of a desaturation detection circuit in which various techniques of this disclosure may be implemented.

[0013] Figure 4 yes Figure 3 A block diagram of an example of a portion of a desaturation detection circuit including a timer that can be used to implement the various techniques of this disclosure.

[0014] Figure 5 A flow chart depicting an example of a method for dynamically adjusting a desaturation detection threshold in a gate driver circuit is depicted. DETAILED DESCRIPTION

[0015] Active short circuit (ASC) refers to a protection function in power electronics systems designed to actively manage and mitigate the effects of short-circuit events. When a short circuit occurs, it can cause a sudden and significant increase in current, which can damage electronic components such as insulated gate bipolar transistors (IGBTs) and field-effect transistors (FETs) due to excessive heating. The ASC protection mechanism is particularly important in systems where power equipment is at risk of short circuits, such as in motor drives, power converters, and inverters. It helps prevent component damage, enabling the system to continue operating or shut down safely under fault conditions.

[0016] ASC works by detecting a short-circuit condition, then actively controlling the power supply to limit the current to a safe level. ASC is used to force the output of the gate driver to a defined state independent of the normal control inputs. ASC is useful in motors operating under "field weakening" control, a technique that allows the back electromotive force (BEMF) to be greater than the DC bus voltage, which offers advantages such as higher motor speed or other optimizations. If control is lost (fault), the back EMF is greater than the DC bus voltage, which could cause damage to the battery or components. When ASC is detected, the system controller generates an ASC signal that is applied to the gate driver circuit, which applies a three-phase short circuit across the motor by turning on all high-side or low-side inverter transistors. By doing so, ASC limits the fault current to a level that the system can handle without causing damage.

[0017] ASC mode is used in "emergency situations" involving high currents that might trip the desaturation detection circuit at normal thresholds. If this happens, the desaturation circuit shuts down the gate driver circuit, defeating the purpose of the ASC function.

[0018] Some desaturation detection circuit approaches set the desaturation threshold to a high voltage to prevent the desaturation detection loop from being triggered during an ASC condition. Alternatively, in other desaturation detection circuit approaches, the ASC signal indicating an ASC condition takes precedence over the desaturation condition. However, this system still requires some protection to prevent damage to the transistors caused by extreme currents.

[0019] The present inventors have recognized the desaturation detection circuit's desaturation detection potential, which is an overcurrent circuit that utilizes two or more desaturation detection circuit thresholds to shift the desaturation threshold in the normal operating mode to a higher voltage when the ASC signal is present in the fault operating mode. Including two or more desaturation detection circuit thresholds allows the desaturation threshold to be lowered during the normal operating mode and raised during the fault operating mode or mode-dependent threshold selection.

[0020] Figure 1FIG1 is a simplified schematic diagram of an example of a current control system 100 in which various techniques of the present disclosure may be implemented. In the non-limiting example shown, the current control system 100 forms part of a motor drive signal chain specifically designed for an alternating current (AC) motor. The current control system 100 includes a three-phase half-bridge circuit 102, a gate driver circuit 104, an isolator assembly 106, a controller 108 with a current feedback circuit 110 and a position feedback circuit 112, and sensors, all of which contribute to the precise and efficient operation of an AC motor 114.

[0021] Three-phase half-bridge circuit 102 includes six transistors (or "power switches"), namely transistors 116a-116c and transistors 118a-118c, arranged in three half-bridge configurations. Each half-bridge, such as transistor 116a and transistor 118a, is responsible for driving one phase of AC motor 114. Controller 108 switches the transistors within these bridges on and off in a synchronized manner, facilitating precise control of the current flowing through the windings of AC motor 114. This control is crucial in managing the speed and torque of AC motor 114.

[0022] Integral to the operation of the three-phase half-bridge circuit 102 is a gate driver circuit 104 coupled to the control terminals (e.g., gate terminals) of transistors, such as insulated gate bipolar transistors (IGBTs) and field effect transistors (FETs). The gate driver circuit 104 provides the necessary drive voltage to drive the transistors, ensuring efficient switching.

[0023] For the upper portion of the three-phase half-bridge circuit 102, which includes transistors 116a-116c, an isolator assembly 106 is coupled to the corresponding gate driver circuit 104. Transistors 116a-116c are coupled to a high-voltage power supply 120, such as a battery stack in an electric vehicle. In some examples, the high-voltage power supply 120 can be 400 volts or higher. The isolator assembly 106 electrically isolates the low-voltage control side of the gate driver (e.g., the side coupled to the controller 108) from the high-voltage power supply side of the three-phase half-bridge circuit 102. This isolation protects the controller 108 from high-voltage transients and facilitates safe signal transmission between the controller 108 and the gate driver circuit 104.

[0024] The controller 108 includes a pulse width modulation (PWM) output circuit 122. The PWM output circuit 122 generates a PWM output signal 124 directed to the gate driver circuit 104. The PWM output signal 124 modulates the duty cycle of the transistor switches, thereby controlling the power delivered to the windings of the AC motor 114. In addition, the controller 108 is equipped with a current feedback circuit 110 and a position feedback circuit 112, which allow for closed-loop control.

[0025] The current feedback circuit 110 is designed to receive input from current sensors, such as the current sensors formed by the current sensing resistor 126 and the current sensing resistor 128, which are located in two phases of the three-phase half-bridge circuit 102. The current feedback circuit 110 monitors the current flowing through the windings of the AC motor 114 via the current sensors, providing real-time feedback to the controller 108. Using this information, the controller 108 can adjust the PWM output signal 124 to ensure that the AC motor 114 operates within the desired parameters.

[0026] Current control system 100 also includes a position sensor 130, such as an optical sensor or a rotary encoder, coupled to AC motor 114. Position sensor 130 provides precise feedback regarding rotor position to position feedback circuitry 112 within controller 108. Accurate position feedback is important for precisely controlling the speed and position of AC motor 114, enabling applications requiring precise motion control.

[0027] Current control system 100 is designed to couple each phase of a three-phase half-bridge circuit 102 to a winding in an AC motor 114, thereby facilitating the conversion of electrical energy into mechanical motion. The inclusion of current and position sensors provides the necessary feedback for controller 108 to fine-tune the operation of AC motor 114 in real time, thereby optimizing performance and efficiency.

[0028] In a motor drive system, such as that implemented in an electric vehicle traction drive, an AC motor, such as AC motor 114, is driven by a three-phase half-bridge circuit controlled by a system controller (e.g., controller 108). The system controller applies a pulse width modulation pattern to each transistor of the three-phase half-bridge circuit, such as the pulse width modulation pattern generated by PWM output circuit 122. The current delivered from the three-phase half-bridge circuit to the AC motor winding inductor exhibits a three-phase sinusoidal waveform. One function of the traction drive system controller is to safely operate the motor, protect the system, and maintain vehicle control in the event of a system short circuit or vehicle accident.

[0029] Desaturation (de-sat) detection circuits are overcurrent protection circuits in power electronic systems, especially in applications involving high power switches such as IGBTs and FETs. The main function of the desaturation circuit is to monitor the voltage across the power switch during operation, such as Figure 1 The desaturation detection circuit may observe two main short circuit conditions: 1) the complementary switch is shorted to supply or ground, which is considered a hard switching fault (HSF), or 2) the motor winding is shorted, which is considered a load fault (FUL).

[0030] Typically, a high current failure (HSF) event occurs during transistor conduction. The voltage across the transistor is initially high. After a time delay, the desaturation circuit is activated to observe whether the voltage remains high during an HSF condition. A load fault event is typically a low current event, which increases the voltage across the transistor with a time constant relative to the motor winding inductance. The desaturation detection circuit monitors the voltage at the collector or drain of power transistors used in motor drive systems to detect excessive current flowing through the power transistor. If excessive current flows through the power transistor during conduction, the voltage increases due to the transistor's resistance. The desaturation detection circuit includes a comparator with thresholds appropriately set for the power transistor design to detect both high current failure (HSF) and high voltage failure (FUL). If the voltage exceeds a predefined threshold, indicating a desaturation condition, the desaturation circuit intervenes by initiating a protective response.

[0031] This response may involve the controller 108 shutting down the affected power switch to prevent excessive power consumption that could lead to thermal runaway and switch failure. By detecting and resolving desaturation events, desaturation circuits play a key role in protecting power electronics systems from overcurrent conditions, ensuring their reliability and longevity. The integration of desaturation circuits is particularly useful in systems where power transistors are subjected to high switching frequencies and load conditions, making them susceptible to rapid degradation and failure without adequate protection.

[0032] When a short-circuit condition is detected, the ASC operates by actively controlling the power supply devices to limit current to a safe level. When an ASC is detected, the system controller (e.g., controller 108) generates an active short-circuit signal 132 to the gate driver circuit 104, which applies a three-phase short circuit across the motor by turning on all high-side or low-side inverter transistors. In some other examples, the system controller turns on both devices in the half-bridge in a controlled manner to discharge the high-voltage supply. By doing so, the ASC limits the fault current to a level that the system can handle without causing damage.

[0033] The present invention describes a desaturation detection circuit that uses two or more desaturation circuit thresholds, which shifts the desaturation threshold in the normal operating mode to a higher voltage when an active short circuit signal 132 is present in the fault operating mode. Figure 3As described in more detail, including two or more desaturation detection circuit thresholds allows for mode-dependent threshold selection, e.g., a lower desaturation threshold during a normal operating mode of the current control system 100, and a higher voltage during a fault operating mode of the current control system 100. The desaturation detection circuit of the present disclosure is designed to modify the threshold to ensure full system protection under all conditions, including an active short circuit (ASC) mode with an elevated threshold, and a normal mode with a reduced threshold, effectively protecting against ASC, high side fault (HSF), and full load (FUL) conditions.

[0034] Fault operation modes with higher voltage thresholds include ASC mode. System failures can occur for other reasons that might not require the ASC function to be enabled. In fault operation mode, the gate driver circuit typically forces the external power switch into the off state. Normal operation mode is when the gate driver circuit operates using PWM signals to open and close the control terminal (e.g., gate) in response to commands from the system controller.

[0035] Figure 2 is a block diagram of an example of a gate driver circuit for driving a transistor that can implement various techniques of the present disclosure. The gate driver circuit 104 is configured to Figure 1 The controller 108 receives the PWM output signal 124. The gate driver circuit 104 includes various circuits, such as a level shift circuit 200, for converting the low voltage PWM output signal 124 to a higher voltage level required to drive the transistor gate.

[0036] The gate driver circuit 104 also includes an overcurrent detection circuit 202. Examples of the overcurrent detection circuit 202 include circuits used for overcurrent protection to detect excessive current through a power transistor, such as a desaturation detection circuit 204. The desaturation detection circuit 204 can implement various techniques of the present disclosure and can be used in Figure 3 The gate driver circuit 104 generates an output signal 206 ( Figure 1 ), the output signal 206 is applied to the control terminal of the power switch, e.g. Figure 1 The gate terminal of one of the transistors 116a-116c and the transistors 118a-118c, for example, Figure 3 The gate terminal 302 in FIG.

[0037] The gate driver circuit 104 may include additional circuitry such as undervoltage lockout (UVLO) circuitry to ensure the gate driver operates within its specified voltage range, thermal shutdown circuitry to prevent operation at excessive temperatures, and fault reporting circuitry to notify the system controller of any detected problems.

[0038] Figure 3 is a schematic diagram of an example of a desaturation detection circuit that may implement various techniques of the present disclosure. The desaturation detection circuit 204 includes a source of current I through a resistor R, which is electrically coupled to a drain terminal 324 of a transistor 304, such as Figure 1 1. The resistor R provides a user-selectable effective threshold offset (=I*R) for the desaturation condition. In some examples, the source of the current I through the resistor R is a current source, such as current source 306, such as a transistor configured to act as a current source. In some examples, the resistor is the source of the current I.

[0039] The desaturation detection circuit 204, as an example of an overcurrent detection circuit, includes a comparator 308, such as a hysteresis comparator. The comparator 308 is configured to receive a voltage V representing a conduction voltage across the transistor 304, for example, provided to a non-inverting terminal. For example, the voltage V representing the conduction voltage across the transistor 304 (V ON ) is generated by a current I through a resistor R and diodes D1 and D2 (eg, high-voltage diodes). The two diodes D1 and D2 may be external components.

[0040] Comparator 308 is further configured to compare the voltage with a signal representing a threshold 310 , for example, provided to the inverting terminal, and generate an output signal 312 when voltage V exceeds threshold 310 , wherein output signal 312 (“DESAT_COMP”) indicates an overcurrent condition of transistor 304 .

[0041] According to the present disclosure, the threshold value represented on signal 310 is selected from a plurality of threshold values ​​314. In the non-limiting example shown, two threshold values ​​are shown, namely a 5 volt (V) threshold value and a 12 volt threshold value. Other examples may include more than two threshold values ​​from which the threshold value is selected, and these threshold values ​​may be different than 5V and 12V.

[0042] Desaturation detection circuit 204 includes a switch 316 configured to select a threshold value 310 from a plurality of threshold values ​​314 based on an operating mode. In some examples, switch 316 is a multiplexer. Switch 316 includes terminals for receiving respective threshold values ​​from the plurality of threshold values. For example, switch 316 includes a first terminal 318 for receiving a 12V threshold value and a second terminal 320 for receiving a 5V threshold value. Switch 316 is configured to select a first threshold value, such as a 5V threshold value, during a first operating mode and to select a second threshold value, such as a 12V threshold value, that is higher than the first threshold value, during a second operating mode (e.g., a fault operating mode).

[0043] In some examples, the second operating mode is an active short circuit mode. For example, the desaturation detection circuit 204 is configured to Figure 1The controller 108 receives the valid short circuit signal 132 .

[0044] Without being bound by theory, the operation of the desaturation detection circuit 204 will be briefly described. When the control terminal 302 of the transistor 304 is turned on, the drain voltage is pulled toward ground, causing the diode to conduct and allowing current to flow through the resistor R. The desaturation detection circuit 204 includes a desaturation clamp 322, such as a transistor, which helps monitor and protect the transistor 304, such as a silicon carbide (SiC) transistor.

[0045] The desaturation clamp 322 holds the input of the comparator 308 low (does not trigger a desaturation event) and protects the internal circuitry when the external power switch (SiC, IGBT, FET, etc.) is turned off and during the blanking period after the power switch is turned on to prevent nuisance tripping at drain / collector voltage transitions.

[0046] To avoid false triggering during the initial activation of transistor 304, the desaturation clamp 322 is turned on to pull node "DESAT" low. The desaturation detection circuit 204 uses a blanking period, for example by applying a blanking signal ("desat_black") to the control terminal of the desaturation clamp 322 and the enable pin of the comparator 308, which pulls the input of the comparator 308 low and disables the comparator 308. After a delay, which may be determined by the specific characteristics of the transistor 304, the blanking signal is removed, which enables the comparator 308 to operate and turn off the desaturation clamp 322, thereby allowing the voltage at the node "DESAT" to increase. Additional delay can be added by adjusting the size of the external capacitor C. Under normal operation, the current through the resistor R and the two voltage drops of the diodes D1 and D2 produce a voltage at the node "DESAT" coupled to the non-inverting input of the comparator 308, for example 3V. During normal operation, the voltage at the node "DESAT" is lower than any of a plurality of thresholds, such as Figure 3 5V and 12V.

[0047] During a fault condition, the current through transistor 304 increases, which in turn increases its drain voltage. This higher voltage, in turn, increases the voltage on node "DESAT." If the voltage on node "DESAT" exceeds the comparator's threshold due to the increased current, comparator 308 trips and outputs signal "DESAT_COMP" to indicate a desaturation condition.

[0048] Figure 4 yes Figure 3 A block diagram of an example of a portion of a desaturation detection circuit 204 that includes a timer that can be used to implement various techniques of the present disclosure. Figure 3 The switch 316 is electrically coupled to control the selection of the switch. Figure 3 As shown, switch 316 is configured to select and output threshold 310 from multiple thresholds 314 based on the operating mode. Timer 400 is coupled to an input of switch 316. Timer 400 receives active short circuit signal 132 and outputs a signal 402 to switch 316 selecting a threshold (e.g., a second threshold).

[0049] In some examples, the timer 400 is configured to control the application of a second threshold (e.g., 12V) to the thyristor during a second operating mode (e.g., an active short circuit mode or other fault operating mode). Figure 3 The duration of the input of comparator 308 of the timer 400 is 100%. For example, timer 400 begins when signal 132 selecting the second threshold of switch 316 is received, and switch 316 selects the second threshold. When the timer expires, timer 400 stops outputting signal 402 selecting the threshold (e.g., the second threshold). In some examples, signal 132 selecting the threshold bypasses timer 400, and the threshold is applied directly to the input of comparator 308.

[0050] In other examples, the timer 400 is configured to control the application of a second threshold (e.g., 12V) to the MOSFET during a second operating mode (e.g., an active short circuit mode or other fault operating mode). Figure 3 The duration of the input of comparator 308 is determined by the timer 400. For example, timer 400 begins upon receiving the selection of a threshold value (e.g., the second threshold value) and outputs a signal selecting the threshold value only after the timer expires. In some examples, the signal selecting the threshold value bypasses timer 400, and the threshold value is applied directly to the input of comparator 308.

[0051] In other examples, the timer 400 is configured to control the duration that the second threshold remains on after the second operating mode (e.g., fault operating mode) is disabled and the first operating mode (e.g., normal operating mode) is enabled. For example, the timer 400 controls the signal representing the second threshold to be applied to the first operating mode even after the active short circuit mode is no longer applied and the normal operating mode is enabled. Figure 3 duration of the comparator 308.

[0052] Figure 5 A flow chart illustrating an example of a method 500 for dynamically adjusting a desaturation detection threshold in a gate driver circuit is depicted.

[0053] At block 502, method 500 includes providing a current to a terminal of a transistor, such as through a resistor. For example, a resistor or transistor acting as a current source is connected to a terminal of a transistor. Figure 3 The resistor R in provides the current.

[0054] At block 504, the method 500 receives a voltage representing a turn-on voltage across a transistor. For example, Figure 3Comparator 308 receives a voltage V representing the on-state voltage across transistor 304 .

[0055] At block 506 , the method 500 compares the voltage to a threshold value, where the threshold value is selected from a plurality of threshold values. For example, the comparator 308 compares the voltage V at its non-inverting terminal to a threshold value 310 selected from a plurality of threshold values ​​314 .

[0056] At block 508 , when the voltage exceeds the threshold, the method 500 generates an output signal, wherein the output signal indicates a desaturation event of the transistor. For example, when the voltage V exceeds the threshold 310 , the comparator 308 generates an output signal “DESAT_COMP”.

[0057] Various annotations

[0058] Each non-limiting claim or example described herein may stand on its own or in various permutations or combinations with one or more of the other examples.

[0059] The above detailed description includes reference to the accompanying drawings that form a part of the detailed description. The accompanying drawings show specific embodiments in which the present invention can be put into practice by way of illustration. These embodiments are also referred to as "examples" in this article. These examples may include elements other than those shown or described. However, the inventors have also considered examples in which only the shown or described elements are provided. In addition, the inventors have also considered examples in which any combination or permutation of those elements shown or described (or one or more claims thereof) is used, whether with respect to a specific example (or another one or more claims thereof), or with respect to other examples shown or described herein (or one or more claims thereof).

[0060] In the event of a conflicting usage between this document and any document incorporated by reference, the usage in this document controls.

[0061] In this document, the terms "a" or "an" are common in patent documents and are used to include one or more, independent of any other instance or usage of "at least one" or "one or more." In this document, the term "or" is used to refer to non-exclusivity, for example, "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise noted. In this document, the terms "including" and "in which" are used as synonyms for the respective terms "comprising" and "wherein." In addition, in the following claims, the terms "including" and "comprising" are open-ended, that is, systems, devices, articles, compositions, formulations, or methods that include other elements in addition to the elements listed after the term in the claim are still considered to fall within the scope of the claim. In addition, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels and are not intended to impose numerical requirements on their objects.

[0062] The method examples described herein may be implemented at least in part by a machine or computer. Some examples may include a computer-readable medium or a machine-readable medium encoded with instructions that are operable to configure an electronic device to perform the methods described in the above examples. The implementation of such methods may include code, such as microcode, assembly language code, high-level language code, etc. Such code may include computer-readable instructions for performing various methods. The code may form part of a computer program product. In addition, in one example, the code may be tangibly stored on one or more volatile, non-transient or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media may include, but are not limited to, a hard disk, a removable disk, a removable optical disk (e.g., an optical disk and a digital video disk), a cassette tape, a memory card or memory stick, a random access memory (RAM), a read-only memory (ROM), etc.

[0063] The above description is intended to be illustrative and not limiting. For example, the above examples (or one or more claims thereof) may be used in combination with each other. Other embodiments may be used, for example, by a person of ordinary skill in the art after reading the above description. The abstract is provided to comply with the provisions of Section 1.72(b) of Chapter 37 of the United States Code of Federal Regulations so that the reader can quickly determine the nature of the technical disclosure. This document is submitted with the understanding that it shall not be used to interpret or limit the scope or meaning of the claims. In addition, in the above detailed description, various features may be combined to simplify the disclosure. This should not be interpreted to mean that unclaimed disclosed features are essential to any claim. On the contrary, the subject matter of the invention may lie in some features of a particular disclosed embodiment. Therefore, the following claims are incorporated into the detailed description as examples or embodiments, each claim existing independently as a separate embodiment, and it is conceivable that these embodiments may be combined with each other in various combinations or arrangements. The scope of the invention should be determined with reference to the appended claims and the full scope of equivalents to which these claims are entitled.

Claims

1. A gate driver circuit for driving a transistor, the gate driver circuit comprising: a current source coupled to the terminals of the transistor; and Overcurrent detection circuit, including: Comparators, configured to: receiving a voltage representing an ON voltage across the transistor; comparing the voltage to a threshold, wherein the threshold is selected from a plurality of thresholds; and When the voltage exceeds the threshold, an output signal is generated, wherein the output signal indicates an overcurrent condition of the transistor.

2. The gate driver circuit according to claim 1 , wherein the overcurrent detection circuit comprises: A switch is configured to select a threshold value from the plurality of threshold values ​​based on an operating mode.

3. The gate driver circuit of claim 2, wherein the switch is a multiplexer.

4. The gate driver circuit of claim 2 , wherein the plurality of thresholds include a first threshold and a second threshold, and wherein the switch is configured to select the first threshold during a first operating mode and to select a second threshold that is higher than the first threshold during a second operating mode. The gate driver circuit of claim 4 , wherein the second operating mode is an active short circuit mode.

6. The gate driver circuit according to claim 4 , wherein the overcurrent detection circuit comprises: A timer is configured to control a duration for which the second threshold is applied during the second operating mode.

7. The gate driver circuit according to claim 4, wherein the overcurrent detection circuit comprises: A timer is configured to control a duration before the second threshold is applied during the second operating mode.

8. The gate driver circuit according to claim 4, wherein the overcurrent detection circuit comprises: A timer is configured to control a duration that the second threshold remains ON after disabling the second operating mode.

9. The gate driver circuit of claim 1, wherein the gate driver circuit is coupled to a control terminal of the transistor, and wherein the transistor forms part of a bridge circuit.

10. A method for dynamically adjusting a desaturation detection threshold in a gate driver circuit, the method comprising: Supplying current to the transistor's terminals; receiving a voltage representing an ON voltage across the transistor; comparing the voltage to a threshold, wherein the threshold is selected from a plurality of thresholds; and An output signal is generated when the voltage exceeds the threshold, wherein the output signal indicates a desaturation event of the transistor.

11. The method according to claim 10, comprising: The threshold is selected from the plurality of thresholds based on an operating mode.

12. The method according to claim 10, wherein the plurality of thresholds include a first threshold and a second threshold, the method comprising: A first threshold is selected during the first operating mode, and a second threshold that is higher than the first threshold is selected during the second operating mode. The method of claim 12 , wherein the second operating mode is an active short circuit mode.

14. The method according to claim 12, comprising: Controlling the duration for which the second threshold is applied during the second operating mode.

15. The method according to claim 12, comprising: Controlling a duration before the second threshold is applied during the second operating mode.

16. The method according to claim 12, comprising: Controlling the duration that the second threshold remains ON after disabling the second operating mode.

17. A desaturation detection circuit comprising: Comparators, configured to: receiving a voltage representing an ON voltage across the transistor; comparing the voltage to a threshold, wherein the threshold is selected from a plurality of thresholds; and generating an output signal when the voltage exceeds the threshold, wherein the output signal indicates an overcurrent condition of the transistor; and A switch is configured to select a threshold value from the plurality of threshold values ​​based on an operating mode.

18. The desaturation detection circuit of claim 17 , wherein the plurality of thresholds include a first threshold and a second threshold, and wherein the switch is configured to select the first threshold during a first operating mode and to select a second threshold that is higher than the first threshold during a second operating mode.

19. The desaturation detection circuit of claim 18, wherein the second operating mode is an active short circuit mode.

20. The desaturation detection circuit of claim 18, comprising: A timer that controls one of the following: a duration for which the second threshold is applied during the second operating mode; a duration before which the second threshold applies during the second mode of operation; or The duration that the second threshold remains ON after disabling the second operating mode.

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