A short circuit protection circuit for a power module

Abstract

The invention discloses a short-circuit protection circuit of a power module, comprising: when the power module is short-circuited, a detection circuit generates a short-circuit fault signal; a signal processing circuit sequentially identifies and latches the short-circuit fault signal; a feedback control circuit generates a driving input-level short-circuit protection signal according to the latched short-circuit fault signal and a driving signal, forming a second-level short-circuit protection; a driving output-level short-circuit protection signal is generated according to the driving input-level short-circuit protection signal and the latched short-circuit fault signal, forming a first-level short-circuit protection; the driving output-level short-circuit protection signal controls the power module to shut down; a controller enters an interrupt program according to the identified short-circuit fault signal, forming a third-level short-circuit protection; the first-level short-circuit protection reaction speed is greater than the second-level short-circuit protection reaction speed, and the second-level short-circuit protection reaction speed is greater than the third-level short-circuit protection reaction speed, and multiple protections realize fast and reliable shutdown of the power module.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a short-circuit protection circuit of a power module. Background Art

[0002] In recent years, SiC MOSFET has been widely used in motor drives, switching power supplies and grid-connected inverters due to its high voltage resistance, high temperature resistance and low loss. In order to ensure the stable and reliable operation of SiC MOSFET, it is very important to design a short-circuit protection circuit with excellent performance. Compared with traditional silicon IGBT, SiC MOSFET has a short short-circuit protection time, which is only 3us at most. The short-circuit protection methods currently available mainly include desaturation short-circuit detection method, inductance detection method, gate voltage detection method and short-circuit detection method based on Rogowski coil. Desaturation short-circuit detection method is the most common and most used method, but this circuit is difficult to achieve fast protection of SiC MOSFET 3us, because the blanking time is set too short and the blanking capacitor value is too small, which will cause false protection due to the coupling current generated on the parasitic capacitor by the large dv / dt during the opening process of SiC MOSFET. There is a contradiction between rapidity and anti-interference, which seriously hinders the high-power experiment of SiC MOSFET module. In addition, this method must be used with a driver chip with a desaturation detection pin, and the protection charging current and protection threshold voltage are not adjustable. The disadvantage of the inductance detection method is that it is only applicable to single-tube protection and has a limited application range. The disadvantages of the gate voltage detection method and the short-circuit detection method based on the Rogowski coil are that the circuit structure is complex, the control algorithm is cumbersome, and the reliability is poor, so they cannot be applied in the industrial field. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the short-circuit protection circuit of the SiC MOSFET module in the prior art, such as slow action, poor anti-interference performance, complex circuit structure and poor reliability, thereby providing a short-circuit protection circuit for a power module.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] An embodiment of the present invention provides a short-circuit protection circuit for a power module, comprising: a detection circuit, a signal processing circuit and a feedback control circuit, wherein the detection circuit has a first end connected to a control end of the power module, a second end connected to a first end of the power module, a third end connected to a second end of the power module, a fourth end and a fifth end connected to an external power supply, and a sixth end connected to a first end of the signal processing circuit; the detection circuit is used to generate a short-circuit fault signal based on a desaturation voltage of the power module and an external power supply voltage when the power module is short-circuited; the signal processing circuit has a second end connected to the first end and a second end of the feedback control circuit, a third end connected to an input end of a controller of the power module, and a fourth end and a fifth end connected to an external power supply; the controller is used to send a drive signal for the power module, and the signal processing circuit is used to generate a short-circuit fault signal based on a desaturation voltage of the power module and an external power supply voltage when the power module is short-circuited; The fault signal is identified and latched in sequence; a feedback control circuit, a third end of which is connected to the output end of the controller of the power module, and a fourth end and a fifth end of which are connected to the external power supply. The feedback control circuit is used to generate a driving input stage short-circuit protection signal according to the short-circuit fault signal and the driving signal to form a second-level short-circuit protection, and to generate a driving output stage short-circuit protection signal according to the driving input stage short-circuit protection signal and the short-circuit fault signal to form a first-level short-circuit protection, and the driving output stage short-circuit protection signal controls the power module to shut down; the identified short-circuit fault signal is transmitted to the controller, and the controller enters the interrupt program according to the identified short-circuit fault signal to form a third-level short-circuit protection; the reaction speed of the first-level short-circuit protection is greater than the reaction speed of the second-level short-circuit protection, and the reaction speed of the second-level short-circuit protection is greater than the reaction speed of the third-level short-circuit protection.

[0006] In one embodiment, the detection circuit includes: a constant current source, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a comparator, a voltage regulator, a first capacitor, and a diode circuit composed of a plurality of diodes connected in series, wherein the cathode of the diode circuit is connected to the first end of the power module, and the anode thereof is connected to the first end of the voltage regulator and the first end of the first capacitor respectively through the second resistor; the first end of the voltage regulator and the first end of the first capacitor are also connected to the control end of the power module through the first capacitor, and to the first end of the constant current source, and are connected to the second end of the constant current source through the third resistor, and the third end of the constant current source is connected to the external power supply; the first end of the voltage regulator and the first end of the first capacitor are also connected to the inverting input end of the comparator, and the second end of the voltage regulator and the second end of the first capacitor are connected to the second end of the power module; the non-inverting input end of the comparator is connected to the external power supply through the fourth resistor, and the output end thereof is connected to the first end of the signal processing circuit, and is connected to the external power supply through the fifth resistor and the fourth resistor in sequence, and the non-inverting input end of the comparator is used to receive a preset short-circuit protection voltage threshold.

[0007] In one embodiment, when the power module is not short-circuited, the power module is in a saturation state. When the power module is short-circuited, the power module exits the saturation state, and the current output by the constant current source and the current flowing through the first resistor charge the first capacitor until the comparator outputs a short-circuit fault signal.

[0008] In one embodiment, the preset short circuit protection voltage threshold and the short circuit protection speed are adjusted by adjusting the first resistor value, the third resistor value, the fourth resistor value, the fifth resistor value and the number of series diodes in the diode circuit.

[0009] In one embodiment, the signal processing circuit includes: a short circuit identification circuit and a fault latch circuit, wherein the short circuit identification circuit has a first end connected to the output end of the comparator, a second end connected to the first end of the fault latch circuit and the input end of the controller respectively, a third end connected to an external power supply, and a fourth end connected to ground, and the short circuit identification circuit is used to identify a short circuit fault signal; the fault latch circuit has a second end connected to the first end and the second end of the feedback control circuit, and a third end connected to the external power supply, and the fault latch circuit is used to latch the short circuit fault signal.

[0010] In one embodiment, the feedback control circuit includes: a drive output stage hardware direct protection circuit and a drive input stage hardware direct protection circuit, wherein the drive input stage hardware direct protection circuit has a first end connected to the output end of the controller of the power module, a second end connected to the second end of the fault latch circuit, a third end connected to the first end of the drive output stage hardware direct protection circuit, and a fourth end connected to an external power supply, and the drive input stage hardware direct protection circuit is used to generate a drive input stage short-circuit protection signal according to a short-circuit fault signal and a drive signal; the drive output stage hardware direct protection circuit has a second end connected to the second end of the fault latch circuit, a third end connected to the control end of the power module, and a fourth end connected to an external power supply, and the drive output stage hardware direct protection circuit is used to generate a drive output stage short-circuit protection signal according to a drive input stage short-circuit protection signal and a short-circuit fault signal.

[0011] In one embodiment, the short circuit identification circuit includes: a sixth resistor, a diode and a second capacitor, wherein the first end of the sixth resistor is connected to an external power supply, and the second end thereof is respectively connected to the anode of the diode and the output end of the comparator; the first end of the second capacitor is grounded, and the second end thereof is respectively connected to the first end of the fault latch circuit and the cathode of the diode.

[0012] In one embodiment, the fault latch circuit includes: a latch chip, whose input end is connected to the second end of the short circuit identification circuit, and whose output end is respectively connected to the second end of the driver input stage hardware direct protection circuit and the second end of the driver output stage hardware direct protection circuit.

[0013] In one embodiment, the driver input stage hardware direct protection circuit includes: a first AND gate logic chip and a driver isolation chip, wherein the first end of the first AND gate logic chip is connected to the output end of the controller, the second end thereof is connected to the second end of the fault latch circuit, and the third end thereof is connected to the first end of the driver output stage hardware direct protection circuit through the driver isolation chip.

[0014] In one embodiment, the driver output stage hardware direct protection circuit includes: a first NOT gate logic chip, a second NOT gate logic chip, a second AND gate logic chip, a third AND gate logic chip, a first switch tube, a second switch tube, a seventh resistor and an eighth resistor, wherein the first end of the second AND gate logic chip and the first end of the third AND gate logic chip are both connected to the second end of the fault latch circuit, and are connected to the external power supply through the seventh resistor; the second end of the second AND gate logic chip is connected to the driver isolation chip, and the second end of the third AND gate logic chip is connected to the driver isolation chip through the first NOT gate logic chip; the third end of the second AND gate logic chip is connected to the control end of the first switch tube through the second NOT gate logic chip, and the third end of the third AND gate logic chip is connected to the control end of the second switch tube; the first end of the first switch tube is connected to the external power supply, the second end of the first switch tube and the first end of the second switch tube are both connected to the control end of the power module, and the second end of the second switch tube is connected to the second end of the power module; the eighth resistor is connected in parallel between the control end and the second end of the power module.

[0015] The technical solution of the present invention has the following advantages:

[0016] 1. The short-circuit protection circuit of the power module provided by the present invention, when the power module is short-circuited, based on the desaturation voltage of the power module and the external power supply voltage, the detection circuit generates a short-circuit fault signal, the short-circuit fault signal notifies the controller to block the wave, and the feedback control circuit implements rapid drive output stage protection for the power module according to the short-circuit fault signal, and implements drive input stage protection for it, and multiple protections realize rapid and reliable shutdown of the power module.

[0017] 2. The short-circuit protection circuit of the power module provided by the present invention utilizes a diode circuit composed of low parasitic capacitance diodes connected in series, a voltage regulator, a blanking capacitor, a constant current source, a high-speed comparator and other main components to form an improved desaturation detection circuit, which has strong anti-interference ability, adjustable charging current and preset short-circuit protection voltage threshold, and does not rely on the driver chip with a desaturation detection function pin, can achieve rapid detection of short-circuit current, and has strong anti-noise ability, and is not prone to false protection.

[0018] 3. The short-circuit protection circuit of the power module provided by the present invention, when the power module is short-circuited, drives the output-stage hardware direct protection circuit and the input-stage hardware direct protection circuit to respectively implement the first-level protection and the second-level protection for the power device according to the short-circuit fault signal. At the same time, the controller enters an interrupt through the short-circuit fault signal to implement software sealing, thereby realizing multiple protections for the power module. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A composition diagram of a specific example of a short-circuit protection circuit for a power module provided by an embodiment of the present invention;

[0021] Figure 2 A specific circuit structure diagram of a detection circuit provided by an embodiment of the present invention;

[0022] Figure 3 A composition diagram of another specific example of a short-circuit protection circuit for a power module provided by an embodiment of the present invention;

[0023] Figure 4 The specific circuit structure of the short circuit identification circuit provided by the embodiment of the present invention;

[0024] Figure 5 The specific circuit structure of the fault latch circuit provided by the embodiment of the present invention;

[0025] Figure 6 A composition diagram of another specific example of a short-circuit protection circuit for a power module provided by an embodiment of the present invention;

[0026] Figure 7 A specific circuit structure diagram of a short-circuit protection circuit for a power module provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Example

[0032] The embodiment of the present invention provides a short-circuit protection circuit for a power module, which is applied to situations where rapid short-circuit protection of power devices is required, such as Figure 1 As shown, it includes: a detection circuit 1, a signal processing circuit 2 and a feedback control circuit 3.

[0033] like Figure 1 As shown, the detection circuit 1 of the embodiment of the present invention has a first end connected to the control end of the power module, a second end connected to the first end of the power module, a third end connected to the second end of the power module, a fourth end and a fifth end both connected to the external power supply, and a sixth end connected to the first end of the signal processing circuit 2. The detection circuit 1 is used to generate a short-circuit fault signal based on the desaturation voltage of the power module and the external power supply voltage when the power module is short-circuited.

[0034] In an embodiment of the present invention, a constant current source, a capacitor and a comparator are arranged inside the detection circuit 1. The comparator generates a short-circuit fault signal according to the capacitor voltage and a preset short-circuit protection voltage threshold. Specifically, when the power module is not short-circuited, the voltage drop between the first end and the second end of the power module is a saturation voltage drop, and the constant current source output current flows into the ground terminal through the power module. When the power module is short-circuited, the power module is desaturated, and the path between the constant current source output current and the ground terminal is disconnected. The constant current source charges the capacitor until the comparator reverses and outputs a short-circuit fault signal. Furthermore, in order to increase the charging current of the capacitor, an expanding resistor is arranged in an embodiment of the present invention. When the power module is short-circuited, the current of the expanding resistor and the current of the constant current source are used to charge the capacitor at the same time.

[0035] The detection circuit 1 of the embodiment of the present invention adopts an improved desaturation detection circuit 1, which is different from the commonly used desaturation circuit in that: first, it does not require a driver chip with a desaturation detection function pin to realize the detection function, but any driver chip can realize the detection function; second, it has an adjustable charging current.

[0036] like Figure 1 As shown, the signal processing circuit 2 of the embodiment of the present invention has a second end connected to the first end and the second end of the feedback control circuit 3, a third end connected to the input end of the controller of the power module, and a fourth end and a fifth end connected to the external power supply. The controller is used to send a driving signal for the power module, and the signal processing circuit 2 is used to identify and latch the short-circuit fault signal in sequence.

[0037] In the embodiment of the present invention, when the power module is short-circuited, the short-circuit fault signal output by the detection circuit 1 is a pulse signal. Therefore, in order to identify and latch the level of the short-circuit fault signal, a signal processing circuit 2 is provided to identify and latch the short-circuit fault signal in sequence.

[0038] like Figure 1As shown, the feedback control circuit 3 of the embodiment of the present invention has a third end connected to the output end of the controller of the power module, and a fourth end and a fifth end connected to the external power supply. The feedback control circuit 3 is used to generate a driving input stage short-circuit protection signal according to the short-circuit fault signal and the driving signal, thereby forming a second-level short-circuit protection, and to generate a driving output stage short-circuit protection signal according to the driving input stage short-circuit protection signal and the short-circuit fault signal, thereby forming a first-level short-circuit protection. The driving output stage short-circuit protection signal controls the power module to be reliably shut down; the identified short-circuit fault signal is transmitted to the controller, and the controller enters the interrupt program according to the identified short-circuit fault signal, thereby forming a third-level short-circuit protection. In an embodiment of the present invention, when a power module is short-circuited, a detection circuit 1 generates a short-circuit fault signal, and sends the short-circuit fault signal to a controller and a feedback control circuit 3 respectively; the feedback control circuit 3 generates a drive input level short-circuit protection signal according to the short-circuit fault signal and the drive signal, and generates a drive output level short-circuit protection signal according to the drive input level short-circuit protection signal and the short-circuit fault signal; the controller enters an interrupt program according to the identified short-circuit fault signal, and generates a drive signal that is all low level, wherein the drive output level short-circuit protection is a first level short-circuit protection, and the drive input level short-circuit protection is a second level short-circuit protection; the controller enters an interrupt for a third level short-circuit protection (control level short-circuit protection); the drive input level short-circuit protection is used to block the drive signal that has been generated by the controller; the drive output level short-circuit protection is based on the drive input level short-circuit protection signal and the short-circuit fault signal, and reliably shuts down the power module.

[0039] In addition, the reaction speed of the first-level short-circuit protection of the embodiment of the present invention is greater than the reaction speed of the second-level short-circuit protection, and the reaction speed of the second-level short-circuit protection is greater than the reaction speed of the third-level short-circuit protection. That is, when the power module is short-circuited, the feedback control circuit first starts the first-level short-circuit protection. At this time, regardless of whether the second-level short-circuit protection and the third-level short-circuit protection are established, the first-level short-circuit protection can reliably shut down the power module. In other words, the second-level short-circuit protection and the third-level short-circuit protection are redundant protections, which can further ensure the reliable shutdown of the power module.

[0040] The short-circuit protection circuit of the power module provided by the embodiment of the present invention, when the power module is short-circuited, based on the desaturation voltage of the power module and the external power supply voltage, the detection circuit generates a short-circuit fault signal, the short-circuit fault signal notifies the controller to block the wave, and the feedback control circuit implements rapid drive output stage protection for the power module according to the short-circuit fault signal, and implements drive input stage protection for it, and multiple protections realize rapid and reliable shutdown of the power module.

[0041] In a specific embodiment, if Figure 2As shown, the detection circuit 1 includes: a constant current source U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a comparator U2, a voltage regulator D4, a first capacitor C1, and a diode circuit composed of a plurality of diodes connected in series (such as Figure 2 D1...D x-1 , D x ).

[0042] like Figure 2 As shown, the cathode of the diode circuit of the embodiment of the present invention is connected to the first end of the power module, and the anode thereof is connected to the first end of the voltage regulator D4 and the first end of the first capacitor C1 respectively through the second resistor R2; the first end of the voltage regulator D4 and the first end of the first capacitor C1 are also connected to the control end of the power module through the first capacitor C1, and to the first end of the constant current source U1, and are connected to the second end of the constant current source U1 through the third resistor R3, and the third end of the constant current source U1 is connected to the external power supply; the first end of the voltage regulator D4 and the first end of the first capacitor C1 are also connected to the inverting input end of the comparator U2, and the second end of the voltage regulator D4 and the second end of the first capacitor C1 are connected to the second end of the power module; the non-inverting input end of the comparator U2 is connected to the external power supply through the fourth resistor R4, and the output end thereof is connected to the first end of the signal processing circuit 2, and is connected to the external power supply through the fifth resistor R5 and the fourth resistor R4 in sequence, and the non-inverting input end of the comparator U2 is used to receive a preset short-circuit protection voltage threshold.

[0043] Specifically, when the power module is not short-circuited, the voltage drop V between the first terminal and the second terminal of the power module is ce The current output by the constant current source U1 flows into the ground terminal through the power module. The capacitor voltage at the positive input terminal of the comparator U2 is less than the preset short-circuit protection voltage threshold at the negative input terminal. The comparator U2 does not output a short-circuit fault signal. When the power module is short-circuited, the power module exits the saturation state. ce Increases, the cathode voltage of the diode circuit is greater than its anode voltage, so the constant current source U1 charges the first capacitor C1, and the voltage of the first capacitor C1 gradually increases until the comparator U2 reverses and outputs a short-circuit fault signal. In addition, the first resistor R1 is a current expansion resistor. When the power module is short-circuited, the gate turn-on voltage of the power module charges the first capacitor C1 through the current of the first resistor R1 and the constant current source U1 at the same time.

[0044] The first capacitor C1 of the embodiment of the present invention is a blanking capacitor, and the diode in the diode circuit is a diode with low parasitic capacitance, so it has a strong anti-noise capability and is not prone to false protection.

[0045] Figure 2The short-circuit protection circuit of the SiC MOSFET power module is taken as an example. In the embodiment of the present invention, the constant current value output by the constant current source U1 is determined by the third resistor R3. The third resistor R3 is based on the constant current output by the constant current source U1 and depends on the gate turn-on voltage V GS+ Increase the charging current I of the blanking capacitor desat , thereby further improving the anti-interference ability of the short-circuit protection circuit, where the charging current I desat The calculation formula is shown in formula (1), where 1.25V is the output voltage of the constant current source U1, which is determined by the chip U1 itself.

[0046]

[0047] The preset short circuit protection voltage threshold V of the embodiment of the present invention th This can be achieved by adjusting the resistance values ​​of the fourth resistor R4 and the fifth resistor R5, as shown in formula (2), where VCC2 is the external power supply voltage.

[0048]

[0049] The embodiment of the present invention can adjust the overcurrent protection point of the power module by adjusting the second resistor R2 and the number of series diodes in the diode circuit. DS_sat As an overcurrent protection point, V DS_sat As shown in formula (3), where V D1 ~V DX is the voltage across each diode in the diode circuit.

[0050] V DS_sat =V th -I desat ×R2-V D1 -...-V DX (3)

[0051] In the embodiment of the present invention, the protection speed t can be adjusted by adjusting the capacitance of the first capacitor C1 and the values ​​of the first resistor R1, the second resistor R2, the third resistor R3 and the number of series diodes in the diode circuit. t is also the blanking time of the first capacitor C1, which is calculated by formula (4).

[0052]

[0053] In a specific embodiment, if Figure 3 As shown, the signal processing circuit 2 includes: a short circuit identification circuit 21 and a fault latch circuit 22 .

[0054] like Figure 3As shown, the short-circuit identification circuit 21 of the embodiment of the present invention has a first end connected to the output end of the comparator U2, a second end connected to the first end of the fault latch circuit 22 and the input end of the controller respectively, a third end connected to the external power supply, and a fourth end grounded. The short-circuit identification circuit 21 is used to identify a short-circuit fault signal.

[0055] In the embodiment of the present invention, when the power module is short-circuited, the detection circuit 1 sends a short-circuit fault signal, and the short-circuit identification circuit 21 identifies the short-circuit fault signal and performs level conversion on it for identification by the feedback control circuit 3 and the controller.

[0056] The specific circuit structure of the short circuit identification circuit 21 of the embodiment of the present invention is as follows: Figure 4 As shown, the short circuit identification circuit 21 includes: a sixth resistor R6, a diode D5 and a second capacitor C2, wherein the first end of the sixth resistor R6 is connected to the external power supply, and the second end thereof is respectively connected to the anode of the diode D5 and the output end of the comparator U2; the first end of the second capacitor C2 is grounded, and the second end thereof is respectively connected to the first end of the fault latch circuit 22 and the cathode of the diode D5.

[0057] Figure 4 In the embodiment, when the power module has no fault, the comparator U2 outputs a high-level voltage VCC2, the IN terminal of the short-circuit identification circuit 21 is a high-level voltage VCC2, and the OUT terminal is a high-level voltage VCC3; when the power module is short-circuited, the comparator U2 outputs a low-level voltage (short-circuit fault signal), the IN terminal of the short-circuit identification circuit 21 is a low-level voltage, and the OUT terminal is a low-level voltage.

[0058] like Figure 3 As shown, the fault latch circuit 22 of the embodiment of the present invention has a second end connected to the first end and the second end of the feedback control circuit 3, and a third end connected to the external power supply. The fault latch circuit 22 is used to latch a short circuit fault signal.

[0059] The fault latch circuit 22 of the embodiment of the present invention mainly realizes the level maintenance of the fault signal, which can be realized by using the latch chip SN74LVC74, whose input end is connected to the short circuit identification circuit 21, and whose output end is respectively connected to the drive input stage hardware direct protection circuit and the drive output stage hardware direct protection circuit. Specifically, Figure 5 As shown, ERROR is the short-circuit fault signal input, and PWM_EN is the short-circuit fault signal level holding output.

[0060] In a specific embodiment, if Figure 6 As shown, the feedback control circuit 33 includes: a driving output stage hardware direct protection circuit 31 and a driving input stage hardware direct protection circuit 32 .

[0061] like Figure 6As shown, the driving input stage hardware direct protection circuit 32 of the embodiment of the present invention has a first end connected to the output end of the controller of the power module, a second end connected to the second end of the fault latch circuit 22, a third end connected to the first end of the driving output stage hardware direct protection circuit 31, and a fourth end connected to the external power supply. The driving input stage hardware direct protection circuit 32 is used to generate a driving input stage short-circuit protection signal according to the short-circuit fault signal and the driving signal;

[0062] like Figure 6 As shown, the drive output stage hardware direct protection circuit 31 of the embodiment of the present invention has a second end connected to the second end of the fault latch circuit 22, a third end connected to the control end of the power module, and a fourth end connected to the external power supply. The drive output stage hardware direct protection circuit 31 is used to generate a drive output stage short-circuit protection signal according to the drive input stage short-circuit protection signal and the short-circuit fault signal.

[0063] The short-circuit protection circuit of the embodiment of the present invention is a three-level protection circuit: first-level short-circuit protection, second-level short-circuit protection and control-level short-circuit protection, wherein the drive output-level hardware direct protection circuit 31 is used to implement the fastest first-level short-circuit protection. If the power module is short-circuited, the drive output-level hardware direct protection circuit 31 directly controls the power module to be reliably shut down. The drive input-level hardware direct protection circuit 32 is used to implement the second-level short-circuit protection. If the power module is short-circuited, the drive input-level hardware direct protection circuit 32 uses the short-circuit fault signal and the drive signal sent by the controller to obtain a low-level drive input-level protection signal. The control-level protection uses the short-circuit fault signal identified by the short-circuit identification circuit 21 to notify the controller to enter an interrupt, thereby realizing software-level drive signal sealing.

[0064] In a specific embodiment, if Figure 7 As shown, the driver input stage hardware direct protection circuit 32 includes: a first AND gate logic chip U3 and a driver isolation chip U4. The first end of the first AND gate logic chip U3 is connected to the output end of the controller, the second end thereof is connected to the second end of the fault latch circuit 22, and the third end thereof is connected to the first end of the driver output stage hardware direct protection circuit 31 through the driver isolation chip U4.

[0065] The drive input stage hardware direct protection circuit 32 of the embodiment of the present invention is used to realize the second-level short-circuit protection. If the power module is short-circuited, the comparator U2 outputs a low-level voltage, the short-circuit identification circuit 21 and the fault latch circuit 22 both output a low-level voltage, and the latched short-circuit fault signal is ANDed with the drive signal (PWM signal) output by the controller to output a low-level signal, which is then transmitted to the drive output stage hardware direct protection circuit 31 through the drive isolation chip U4.

[0066] In a specific embodiment, if Figure 7As shown, the driver output stage hardware direct protection circuit 31 includes: a first NOT gate logic chip U5, a second NOT gate logic chip U6, a second AND gate logic chip U7, a third AND gate logic chip U8, a first switch tube Q1, a second switch tube Q2, a seventh resistor R7 and an eighth resistor R8.

[0067] like Figure 7 As shown, the first end of the second AND gate logic chip U7 and the first end of the third AND gate logic chip U8 of the embodiment of the present invention are both connected to the second end of the fault latch circuit 22, and are connected to the external power supply through the seventh resistor R7; the second end of the second AND gate logic chip U7 is connected to the drive isolation chip U4, and the second end of the third AND gate logic chip U8 is connected to the drive isolation chip U4 through the first NOT gate logic chip U5; the third end of the second AND gate logic chip U7 is connected to the control end of the first switch tube Q1 through the second NOT gate logic chip U6, and the third end of the third AND gate logic chip U8 is connected to the control end of the second switch tube Q2; the first end of the first switch tube Q1 is connected to the external power supply, the second end of the first switch tube Q1 and the first end of the second switch tube Q2 are both connected to the control end of the power module, and the second end of the second switch tube Q2 is connected to the second end of the power module; the eighth resistor R8 is connected in parallel between the control end and the second end of the power module.

[0068] Figure 7 In the embodiment, the IN terminal of the driver output stage hardware direct protection circuit 31 is connected to the driver isolation chip U4, and the EN terminal is connected to the fault latch circuit 22. The logic implemented by the driver output stage hardware direct protection circuit 31 is shown in Table 1, where "1" represents a high level and "0" represents a low level.

[0069] Table 1

[0070]

[0071]

[0072] In summary, the specific working principle of the short-circuit protection circuit of the embodiment of the present invention is as follows:

[0073] (1) When the power module is not short-circuited, the constant current output by the constant current source U1 flows into the reference ground through the diode D5 circuit, the voltage across the first capacitor C1 is less than the preset short-circuit protection voltage threshold, the comparator U2 outputs a high-level voltage, the D5 of the short-circuit identification circuit 21 is not turned on, and its OUT terminal outputs a high-level voltage which is respectively input to the fault latch circuit 22 and the controller. After the fault latch circuit 22 latches the high-level voltage, it is respectively input to the first AND gate logic chip U3 and the EN terminal of the drive output stage hardware direct protection circuit 31. At this time, the controller still outputs the drive signal normally. After the drive signal and the high-level voltage are ANDed, it is still the drive signal issued by the controller. The drive signal is transmitted to the IN terminal of the drive output stage hardware direct protection circuit 31 through the drive isolation chip U4. At this time, the EN terminal of the drive output stage hardware direct protection circuit 31 is a high-level voltage. Therefore, according to the logic described in Table 1, the OUT terminal of the drive output stage hardware direct protection circuit 31 is the drive signal normally output by the controller, and the drive signal controls the power device to be normally turned on or off.

[0074] (2) When the power device is short-circuited, the power device exits the saturation state, the first capacitor C1 is charged until the comparator U2 outputs a low-level voltage, D5 of the short-circuit identification circuit 21 is turned on, and the low-level voltage outputted from its end is respectively inputted into the fault latch circuit 22 and the controller. After the fault latch circuit 22 latches the low-level voltage, it is respectively inputted into the first AND gate logic chip U3 and the EN end of the drive output stage hardware direct protection circuit 31. At this time, the EN end of the driver output stage hardware direct protection circuit 31 is a low level voltage (a short-circuit fault signal after identification and latching in sequence). According to the logic described in Table 1, the OUT end of the driver output stage hardware direct protection circuit 31 outputs a low level, so that the power device can be reliably shut down, and a fast first-level protection is achieved; at the same time, the drive signal is still a 0V low level voltage after being ANDed with the low level voltage, and the 0V low level voltage is transmitted to the IN end of the driver output stage hardware direct protection circuit 31 through the driver isolation chip U4. At this time, no matter whether the EN end of the driver output stage hardware direct protection circuit 31 is a high level voltage or a low level voltage, according to the logic described in Table 1, the OUT end of the driver output stage hardware direct protection circuit 31 outputs a low level (driver output stage short-circuit protection signal), and the power device can still be reliably shut down, and the second-level protection of the module is achieved; the fault signal enters the controller through an interrupt, so that the controller realizes the software-level drive signal sealing, and the third-level protection of the module is achieved.

[0075] The short-circuit protection circuit of the power module provided in the embodiment of the present invention uses a diode circuit composed of low parasitic diodes connected in series, a voltage regulator and a blanking capacitor, a constant current source, a high-speed comparator and other main components to form an improved desaturation detection circuit, which has strong anti-interference ability, adjustable charging current and preset short-circuit protection voltage threshold, and can realize rapid detection of short-circuit current without relying on the desaturation detection function pin of the driving chip, so that it has strong anti-noise ability and is not prone to false protection.

[0076] The short-circuit protection circuit of the power module provided by the embodiment of the present invention, when the power module is short-circuited, drives the output-stage hardware direct protection circuit and the input-stage hardware direct protection circuit to respectively implement the first-level protection and the second-level protection for the power device according to the short-circuit fault signal. At the same time, the controller enters an interrupt through the short-circuit fault signal to implement software sealing, thereby realizing multiple protections for the power module.

[0077] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A short-circuit protection circuit for a power module, characterized in that: include: Detection circuit, signal processing circuit and feedback control circuit, wherein: a detection circuit, wherein a first end of the detection circuit is connected to the control end of the power module, a second end of the detection circuit is connected to the first end of the power module, a third end of the detection circuit is connected to the second end of the power module, a fourth end and a fifth end of the detection circuit are both connected to an external power supply, and a sixth end of the detection circuit is connected to the first end of the signal processing circuit, wherein the detection circuit is used to generate a short-circuit fault signal based on a desaturation voltage of the power module and an external power supply voltage when the power module is short-circuited; A signal processing circuit, wherein the second end thereof is connected to the first end and the second end of the feedback control circuit, the third end thereof is connected to the input end of the controller of the power module, and the fourth end and the fifth end thereof are connected to an external power supply, the controller is used to send a driving signal of the power module, and the signal processing circuit is used to sequentially identify and latch the short-circuit fault signal; A feedback control circuit, wherein the third end is connected to the output end of the controller of the power module, and the fourth and fifth ends are connected to the external power supply, wherein the feedback control circuit is used to generate a driving input stage short-circuit protection signal according to the short-circuit fault signal and the driving signal to form a second-level short-circuit protection, and to generate a driving output stage short-circuit protection signal according to the driving input stage short-circuit protection signal and the short-circuit fault signal to form a first-level short-circuit protection, wherein the driving output stage short-circuit protection signal controls the power module to shut down; The short-circuit fault signal after identification and latching is transmitted to the controller, and the controller enters the interrupt program according to the identified short-circuit fault signal, forming the third level of short-circuit protection; The reaction speed of the first level short circuit protection is greater than the reaction speed of the second level short circuit protection, and the reaction speed of the second level short circuit protection is greater than the reaction speed of the third level short circuit protection.

2. The short-circuit protection circuit of the power module according to claim 1, characterized in that: The detection circuit includes: a constant current source, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a comparator, a voltage stabilizer, a first capacitor, and a diode circuit composed of a plurality of diodes connected in series, wherein: The cathode of the diode circuit is connected to the first end of the power module, and the anode of the diode circuit is connected to the first end of the voltage regulator and the first end of the first capacitor respectively through a second resistor; The first end of the voltage regulator and the first end of the first capacitor are also connected to the control end of the power module through the first capacitor, and to the first end of the constant current source, and are connected to the second end of the constant current source through a third resistor, and the third end of the constant current source is connected to an external power supply; The first end of the voltage regulator and the first end of the first capacitor are also connected to the inverting input end of the comparator, and the second end of the voltage regulator and the second end of the first capacitor are connected to the second end of the power module; The non-inverting input terminal of the comparator is connected to the external power supply through the fourth resistor, and its output terminal is connected to the first terminal of the signal processing circuit, and is connected to the external power supply through the fifth resistor and the fourth resistor in sequence. The non-inverting input terminal of the comparator is used to receive a preset short-circuit protection voltage threshold.

3. The short-circuit protection circuit of the power module according to claim 2, characterized in that: When the power module is not short-circuited, the power module is in a saturated state. When the power module is short-circuited, the power module exits the saturated state. The current output by the constant current source and the current flowing through the first resistor charge the first capacitor until the comparator outputs a short-circuit fault signal.

4. The short-circuit protection circuit of the power module according to claim 3, characterized in that: By adjusting the first resistor, the third resistor resistance, the fourth resistor resistance, the fifth resistor resistance and the number of series-connected diodes in the diode circuit, the preset short-circuit protection voltage threshold and the short-circuit protection speed are adjusted.

5. The short-circuit protection circuit of the power module according to claim 4, characterized in that: The signal processing circuit includes: a short circuit identification circuit and a fault latch circuit, wherein: A short circuit identification circuit, wherein a first end thereof is connected to the output end of the comparator, a second end thereof is respectively connected to the first end of the fault latch circuit and the input end of the controller, a third end thereof is connected to the external power supply, and a fourth end thereof is grounded, wherein the short circuit identification circuit is used to identify the short circuit fault signal; A fault latch circuit has a second end connected to the first end and the second end of the feedback control circuit, and a third end connected to an external power supply. The fault latch circuit is used to latch the short-circuit fault signal.

6. The short-circuit protection circuit of the power module according to claim 5, characterized in that: The feedback control circuit includes: a drive output stage hardware direct protection circuit and a drive input stage hardware direct protection circuit, wherein: A drive input stage hardware direct protection circuit, wherein a first end thereof is connected to an output end of the controller of the power module, a second end thereof is connected to a second end of the fault latch circuit, a third end thereof is connected to a first end of the drive output stage hardware direct protection circuit, and a fourth end thereof is connected to an external power supply, wherein the drive input stage hardware direct protection circuit is used to generate a drive input stage short circuit protection signal according to a short circuit fault signal and a drive signal; The drive output stage hardware direct protection circuit has a second end connected to the second end of the fault latch circuit, a third end connected to the control end of the power module, and a fourth end connected to an external power supply. The drive output stage hardware direct protection circuit is used to generate a drive output stage short-circuit protection signal according to the drive input stage short-circuit protection signal and the short-circuit fault signal.

7. The short-circuit protection circuit of the power module according to claim 6, characterized in that: The short circuit identification circuit includes: a sixth resistor, a diode and a second capacitor, wherein: A first end of the sixth resistor is connected to the external power supply, and a second end thereof is connected to the anode of the diode and the output end of the comparator respectively; A first end of the second capacitor is grounded, and a second end thereof is respectively connected to the first end of the fault latch circuit and the cathode of the diode.

8. The short-circuit protection circuit of the power module according to claim 7, characterized in that: The fault latch circuit comprises: a latch chip, whose input end is connected to the second end of the short circuit identification circuit, and whose output end is respectively connected to the second end of the driving input stage hardware direct protection circuit and the second end of the driving output stage hardware direct protection circuit.

9. The short-circuit protection circuit of the power module according to claim 8, characterized in that: The drive input stage hardware direct protection circuit comprises: a first AND gate logic chip and a drive isolation chip, wherein: The first end of the first AND gate logic chip is connected to the output end of the controller, the second end thereof is connected to the second end of the fault latch circuit, and the third end thereof is connected to the first end of the driver output stage hardware direct protection circuit through the driver isolation chip.

10. The short-circuit protection circuit of the power module according to claim 9, characterized in that: The drive output stage hardware direct protection circuit comprises: a first NOT gate logic chip, a second NOT gate logic chip, a second AND gate logic chip, a third AND gate logic chip, a first switch tube, a second switch tube, a seventh resistor and an eighth resistor, wherein: The first end of the second AND gate logic chip and the first end of the third AND gate logic chip are both connected to the second end of the fault latch circuit, and are connected to the external power supply through the seventh resistor; The second end of the second AND gate logic chip is connected to the driver isolation chip, and the second end of the third AND gate logic chip is connected to the driver isolation chip through the first NOT gate logic chip; The third end of the second AND gate logic chip is connected to the first switch tube control end through the second NOT gate logic chip, and the third end of the third AND gate logic chip is connected to the second switch tube control end; The first end of the first switch tube is connected to the external power supply, the second end of the first switch tube and the first end of the second switch tube are both connected to the control end of the power module, and the second end of the second switch tube is connected to the second end of the power module; The eighth resistor is connected in parallel between the control terminal and the second terminal of the power module.

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