A power tube desaturation protection circuit and energy storage power supply

Abstract

The embodiment of the present invention discloses a power tube desaturation protection circuit, including a unidirectional conduction module and a detection drive module, wherein the unidirectional conduction module is connected to a drive signal source, and the drive signal output by the drive signal source has the same control timing as the signal driving the power tube; the detection drive module is used to respond to the conduction voltage drop of the unidirectional conduction module and the conduction voltage drop of the power tube to receive the drive voltage when the drive signal is at a high level, and output a protection signal when the drive voltage is greater than or equal to a preset voltage; when the drive signal is at a low level, the protection signal is stopped from being output in response to the low-level drive signal. The embodiment of the present invention outputs a drive voltage that follows the conduction voltage drop of the power tube when the drive signal is at a high level, and the detection drive module outputs a protection signal when the drive voltage is greater than or equal to the preset voltage, so as to realize overcurrent detection and protection of the power tube. The power consumption of the power tube desaturation protection circuit can be reduced, reliability can be improved, and cost can be reduced.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of electronic technology, and in particular to a power tube desaturation protection circuit and an energy storage power supply. Background Art

[0002] With the rapid development of power electronics technology, the types and forms of power products for consumers are gradually enriched. At the same time, consumers have higher and higher requirements for the functions, performance and reliability of power products. Therefore, the protection strategy of power products needs to be more comprehensive and the reliability index requirements are more stringent. The key device that determines the reliability of power products is the power tube, which mainly includes insulated gate bipolar transistor (IGBT), metal-oxide semiconductor field-effect transistor (MOSFET, MOS tube for short), etc. IGBT has been widely used in high-power power electronic converters, conversion systems above 600V, AC motors, inverters, switching power supplies and other fields due to its advantages such as high current density, low saturation voltage drop, strong current handling capability and high switching speed.

[0003] The most common fault type encountered by IGBT in actual operation is overcurrent fault. Overcurrent fault means that during the operation of IGBT, the collector current exceeds the rated value for a long time. Overcurrent will cause the module to be too hot and unable to be discharged in time, causing the IGBT module to overheat. This process is called desaturation.

[0004] The current method of protecting power IGBTs is to connect Hall devices and sampling resistors in series in the circuit loop of the power IGBT, and determine whether the power IGBT is working in an overcurrent state by detecting the current value flowing through the power device through the Hall devices and sampling resistors.

[0005] However, the solution of connecting Hall devices and sampling resistors in series has very high power consumption under high current (greater than 100A) conditions, and the heating problem of the device itself needs to be dealt with, and the efficiency of the whole machine also needs to be considered. Secondly, the series connection of Hall devices and sampling resistors requires additional operation circuits to process the signals. The operation circuits are easily interfered with, and there are certain risks in the working reliability of the detection circuit. In addition, the solution of connecting Hall devices and sampling resistors in series increases the hardware cost to a certain extent. Summary of the invention

[0006] The main technical problem solved by the embodiments of the present invention is to provide a power tube desaturation protection circuit and an energy storage power supply, which can solve the problems of high power consumption, low reliability and high cost in the existing power tube detection and protection scheme through series connection of Hall devices and sampling resistors.

[0007] In order to solve the above technical problems, a technical solution adopted in an embodiment of the present invention is: to provide a power tube desaturation protection circuit, including: a unidirectional conduction module and a detection and driving module, the input end of the unidirectional conduction module is used to connect a drive signal source, the output end of the unidirectional conduction module is used to connect the power tube, and the detection and driving module is also connected to the input end of the unidirectional conduction module; wherein the drive signal output by the drive signal source has the same control timing as the signal driving the power tube; the detection and driving module is used to receive the drive voltage in response to the conduction voltage drop of the unidirectional conduction module and the conduction voltage drop of the power tube when the drive signal is at a high level, and output a protection signal when the drive voltage is greater than or equal to a preset voltage; when the drive signal is at a low level, stop outputting the protection signal in response to the low-level drive signal.

[0008] In some embodiments, when the driving voltage is less than the preset voltage, the detection driving module stops outputting the protection signal; the driving voltage responds to the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module.

[0009] In some embodiments, when the drive signal is at a high level, the power tube and the unidirectional conduction module are used to transmit the voltage of the drive signal source to the detection drive module, and clamp it to the sum of the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module, so that the detection drive module receives the drive voltage; when the drive signal is at a low level, the detection drive module responds to the low-level drive signal and the drive voltage received is less than the preset voltage, so as to stop outputting the protection signal.

[0010] In some embodiments, the driving signal is a signal for driving the power tube.

[0011] In some embodiments, the detection and driving module includes a detection unit and a driving unit; the input end of the detection unit is connected to the input end of the unidirectional conduction module, and the output end of the detection unit is connected to the input end of the driving unit; the detection unit is used to respond to the conduction voltage drop of the unidirectional conduction module and the conduction voltage drop of the power tube to receive the driving voltage when the driving signal is at a high level, and output a detection signal when the driving voltage is greater than or equal to the preset voltage; when the driving signal is at a low level, respond to the low level driving signal to stop outputting the detection signal; the driving unit is used to output the protection signal when receiving the detection signal; and stop outputting the protection signal when the detection signal is not received.

[0012] In some embodiments, the detection unit includes a voltage regulator diode ZD1, a resistor R5, a resistor R6, a resistor R7, a capacitor C2 and a reference regulator U1, and the driving unit includes an optical coupler U2, a resistor R10 and a capacitor C3; the cathode of the voltage regulator diode ZD1 is connected to the input end of the unidirectional conduction module, the anode of the voltage regulator diode ZD1 is connected to the first end of the resistor R5, the second end of the resistor R5 is connected to the first end of the resistor R6, the first end of the capacitor C2 and the reference end of the reference regulator U1, and the cathode of the reference regulator U1 is connected to the The second end of the resistor R7 is connected, the anode of the reference regulator U1, the second end of the resistor R6 and the second end of the capacitor C2 are connected to the first reference ground; the first end of the resistor R7 is connected to the cathode of the optocoupler U2, the anode of the optocoupler U2 is connected to the first voltage source, the collector of the optocoupler U2 is connected to the second voltage source, the emitter of the optocoupler U2 is connected to the first end of the resistor R10 and the first end of the capacitor C3, the emitter of the optocoupler U2 is used to output the protection signal, and the second end of the resistor R10 and the second end of the capacitor C3 are connected to the second reference ground.

[0013] In some embodiments, the power tube desaturation protection circuit also includes a delay module, which is connected to the input end of the unidirectional conduction module and the detection drive module; the delay module is used to delay the detection drive module to receive the drive voltage for a preset time under the action of the high-level drive signal; the preset time is greater than the conduction time of the power tube.

[0014] In some embodiments, the power tube desaturation protection circuit further includes a discharge module, which is connected between the input end of the unidirectional conduction module and the driving signal source; when the driving signal is at a low level, the discharge module discharges the electric energy stored in the delay module.

[0015] In some embodiments, the discharge module includes a diode D2, a resistor R8 and a resistor R9, the anode of the diode D2 is connected to the input end of the unidirectional conduction module and the first end of the resistor R8, the cathode of the diode D2 is connected to the first end of the resistor R9, and the second end of the resistor R9 is connected to the second end of the resistor R8 and the driving signal source.

[0016] To solve the above technical problems, another technical solution adopted in the embodiment of the present invention is: providing an energy storage power supply, a plurality of power tubes; and a plurality of power tube desaturation protection circuits as described above; one power tube is connected to one power tube desaturation protection circuit.

[0017] The beneficial effects of the embodiments of the present invention are as follows: Different from the prior art, the embodiments of the present invention output a driving voltage that follows the on-state voltage drop of the power tube when the driving signal is at a high level as a basis for judging whether the collector current exceeds the rated value; the detection driving module outputs a protection signal when the driving voltage is greater than or equal to a preset voltage to realize overcurrent detection and protection of the power tube. The power consumption of the power tube desaturation protection circuit can be reduced, its reliability can be improved, and the hardware cost can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the waveform diagram of the on-state voltage drop and collector current of the IGBT;

[0019] Figure 2 This is the waveform diagram when the IGBT desaturates;

[0020] Figure 3 It is a structural schematic diagram of a power tube desaturation protection circuit provided by an embodiment of the present invention;

[0021] Figure 4 is a structural schematic diagram of a detection drive module provided by an embodiment of the present invention;

[0022] Figure 5 It is a circuit principle diagram of a power tube desaturation protection circuit provided by an embodiment of the present invention;

[0023] Figure 6 It is a structural schematic diagram of another power tube desaturation protection circuit provided by an embodiment of the present invention;

[0024] Figure 7 It is a circuit principle diagram of another power tube desaturation protection circuit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "bottom" and the like used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present application 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 a limitation on the present application. In addition, the terms "first", "second", "third" and the like are used only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0026] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0027] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0028] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0029] Power tubes mainly include IGBT, MOS tubes, etc. In order to achieve the protection of power tubes, the solution of connecting Hall devices and sampling resistors in series is often adopted. The advantages and disadvantages of the solution of connecting Hall devices and sampling resistors in series are described below:

[0030] Series Hall device: Connect a Hall device in series in the current loop of the power tube. By calculating the detection value of the Hall device and then comparing the threshold value and triggering the overcurrent signal, the software turns off the drive signal of the power tube to achieve the purpose of protection.

[0031] Series sampling resistor: The design idea is similar to the method of series Hall device. The detection value of the sampling resistor is calculated, and then the threshold is compared and the overcurrent signal is triggered. The software turns off the drive signal of the power tube to achieve the purpose of protection.

[0032] However, the solution of connecting Hall devices or sampling resistors in series has the following defects:

[0033] First of all, the solution of connecting Hall devices or sampling resistors in series can be applicable to small current models, but under high current (greater than 100A) conditions, the power consumption of the solution of connecting Hall devices or sampling resistors in series is quite high. Not only does it need to deal with the heating problem of the device itself, but it also needs to consider the efficiency of the entire machine. Therefore, the solution of connecting Hall devices or sampling resistors in series is not suitable for high current models.

[0034] Secondly, the series connection of Hall devices or sampling resistors requires additional operation circuits to process the signals. In addition, the power tube works under high-frequency conditions, and the operation circuit is easily interfered, which leads to certain risks in the working reliability of the detection circuit.

[0035] Finally, whether it is a series Hall device or a sampling resistor solution, the additional circuit increases the cost of the product to a certain extent.

[0036] In order to solve the above-mentioned problems and reliably protect power tube devices, the application method of the present invention provides a circuit scheme for detecting desaturation of power tubes using discrete devices. Before describing the circuit scheme, it is necessary to first describe the working state of the power tube when desaturation occurs in the power tube. Figure 1 The waveform of the on-state voltage drop and collector current of an IGBT is shown in FIG. Figure 1 In the figure, the horizontal axis is the on-state voltage drop V of the IGBT. CE , the vertical axis is the current I flowing through the two ends of the CE pole C . Figure 1 It mainly explains the conduction voltage drop V of IGBT when it is turned on. CE With the gate drive voltage V GE and the actual current I flowing through the CE terminals C , the current I flowing through the two ends of the CE pole C The larger the IGBT conduction voltage drop V CE The higher.

[0037] Figure 2 It shows a waveform diagram when an IGBT desaturates. Figure 2 The horizontal axis is the time axis, and the vertical axis shows the amplitude of the corresponding physical quantity. Figure 2 When the current is too high, the IGBT will desaturate. At this time, all the voltage of the driving power supply is loaded on both ends of the CE pole of the IGBT. If it lasts too long, the IGBT will be burned out. The recommended driving power supply voltage of the IGBT is usually 14V-16.5V. Figure 1 The on-state voltage drop V of the IGBT CE , when the driving power supply is fixed, the on-state voltage drop V CE As the flow passes by C The current change, I C The larger the current, the greater the conduction voltage drop V CE The bigger.

[0038] Therefore, the embodiment of the present invention provides a power tube desaturation protection circuit, and its structural schematic diagram is as follows: Figure 3 As shown, the power tube desaturation protection circuit includes a unidirectional conduction module 110 , a detection and driving module 120 and a delay module 130 .

[0039] The input end of the unidirectional conduction module 110 is used to connect to the driving signal source 20, the output end of the unidirectional conduction module 110 is used to connect to the power tube 30, the detection and driving module 120 is also connected to the input end of the unidirectional conduction module 110, and the delay module 130 is connected to the input end of the unidirectional conduction module 110 and the detection and driving module 120.

[0040] It should be noted that the driving signal output by the driving signal source 20 has the same control timing as the signal driving the power tube 30. The control timing refers to the order in which the signals are arranged in time. The timing of the signal output by the driving signal source and the signal driving the power tube is the same, which means that the two signals are synchronized in time, that is, when the signal driving the power tube is at a high level, the driving signal is also at a high level, and when the signal driving the power tube is at a low level, the driving signal is also at a low level.

[0041] As an example but not limitation, the control signal of the driving signal source can be a signal for driving the power tube. When the signal for driving the power tube is at a high level, the driving signal source outputs a high-level driving signal in response to the high-level control signal; when the signal for driving the power tube is at a low level, the driving signal source outputs a low-level driving signal in response to the low-level control signal. Of course, the most direct implementation is that the driving signal source is a signal source for driving the power tube 30.

[0042] The detection drive module 120 is used to receive the drive voltage in response to the conduction voltage drop of the unidirectional conduction module 110 and the conduction voltage drop of the power tube 30 when the drive signal is at a high level, and output a protection signal when the drive voltage is greater than or equal to a preset voltage; when the drive signal is at a low level, the detection drive module 120 stops outputting the protection signal in response to the low-level drive signal.

[0043] When the driving signal is at a high level, the power tube 30 and the unidirectional conduction module 110 are used to transmit the voltage of the driving signal source to the detection driving module 120, and clamp it to the sum of the conduction voltage drop of the power tube 30 and the conduction voltage drop of the unidirectional conduction module 110, so that the detection driving module 120 receives the driving voltage; when the driving signal is at a low level, the detection driving module 120 responds to the driving voltage received by the low-level driving signal being less than the preset voltage, so as to stop outputting the protection signal; when the driving voltage is reduced to less than the preset voltage, the detection driving module stops outputting the protection signal. The driving voltage responds to the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module, that is, the driving voltage follows the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module; in other words, the driving voltage depends on the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module. As the most direct implementation method, the driving voltage is equal to the sum of the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module.

[0044] As an example but not a limitation, in the embodiment of the present application, the driving signal acting on the detection driving module 120 is a signal for driving the power tube 30 , that is, the detection driving module 120 and the power tube 30 share a driving signal.

[0045] As an example but not a limitation, the power tube desaturation protection circuit provided in the embodiments of the present invention uses IGBT as an application object. Of course, the power tube desaturation protection circuit can also be applied to power tubes such as MOS tubes that may experience desaturation.

[0046] The delay module 130 is used to delay the detection drive module 120 to receive the drive voltage for a preset time under the action of a high-level drive signal; it should be emphasized that the preset time is greater than the conduction time of the power tube.

[0047] According to the above description, the condition for the occurrence of the desaturation phenomenon is that the IGBT tube is in the open state, and the current flowing through the CE poles of the IGBT tube is greater than the rated current, then the IGBT tube is desaturated; when the IGBT tube is in the closed state, desaturation detection and protection may not be performed; the power tube desaturation protection circuit provided in the embodiment of the present application cleverly utilizes the driving signal of the IGBT tube, effectively realizes the desaturation detection and protection of the IGBT tube when the IGBT tube is in the open state, quickly turns off the IGBT tube, and stops the corresponding power circuit from working.

[0048] In some embodiments of the present application, a detection drive module is provided, and its structural diagram is as follows: Figure 4 As shown, the detection drive module 120 includes a detection unit 121 and a drive unit 122; the input end of the detection unit 121 is connected to the input end of the unidirectional conduction module 110, the output end of the detection unit 121 is connected to the input end of the drive unit 122, and the output end of the detection unit 122 is connected to the control device.

[0049] The detection unit 121 is used to receive the driving voltage in response to the conduction voltage drop of the unidirectional conduction module 110 and the conduction voltage drop of the power tube when the driving signal is at a high level, and output a detection signal when the driving voltage is greater than or equal to a preset voltage; when the driving signal is at a low level, the detection signal is stopped from being output in response to the low-level driving signal; the driving unit 122 is used to output a protection signal when a detection signal is received; when no detection signal is received, the driving signal 122 stops outputting the protection signal.

[0050] In some embodiments of the present application, Figure 2 The circuit schematic diagram of the power tube desaturation protection circuit is shown in Figure 5 As shown, the application object is the lower arm IGBT tube Q2 of the half-bridge circuit. It should be noted that the power tube desaturation protection circuit can achieve the same function and effect in both the upper arm IGBT tube and the lower arm power IGBT tube. Among them, the detection unit 121 includes a voltage regulator diode ZD1, a resistor R5, a resistor R6, a resistor R7, a capacitor C2 and a reference regulator U1, and the driving unit 122 includes an optical coupler U2, a resistor R10 and a capacitor C3; the unidirectional conduction module 110 includes a diode D1, and the delay module 130 includes a capacitor C1 and a resistor R11.

[0051] The cathode of the diode D1 is connected to the collector of the IGBT tube Q2, the cathode of the voltage regulator diode ZD1 is connected to the anode of the diode D1, the first end of the capacitor C1, the first end of the resistor R11 and the driving signal source, and the anode of the diode D1 serves as the receiving end of the driving signal PWM_G2; the anode of the voltage regulator diode ZD1 is connected to the first end of the resistor R5, the second end of the resistor R5 is connected to the first end of the resistor R6, the first end of the capacitor C2 and the reference end of the reference regulator U1, the cathode of the reference regulator U1 is connected to the second end of the resistor R7, and the emitter of the IGBT tube Q2, the second end of the capacitor C1, the second end of the resistor R11, the anode of the reference regulator U1, the second end of the resistor R6 and the second end of the capacitor C2 are connected to the first reference ground GND_BUS.

[0052] The first end of the resistor R7 is connected to the cathode of the optocoupler U2, the anode of the optocoupler U2 is connected to the first voltage source VCC_DR, the collector of the optocoupler U2 is connected to the second voltage source VCC_MCU, the emitter of the optocoupler U2 is connected to the first end of the resistor R10 and the first end of the capacitor C3, the emitter of the optocoupler U2 is used to output the protection signal IGBT_SC, and the second end of the resistor R10 and the second end of the capacitor C3 are connected to the second reference ground GND_MCU.

[0053] Specifically, when the drive signal PWM_G2 is at a high level, the IGBT tube Q2 is turned on, the drive signal PWM_G2 charges the capacitor C1, and the IGBT tube Q2 is turned on; when the capacitor C1 is charged for a preset time and the voltage is higher than the conduction voltage drop V CE The forward voltage drop of diode D1 is V F After the sum, diode D1 is turned on; the voltage V across capacitor C1 C1 =V F +V CE That is, when the IGBT tube Q2 is turned on, the voltage across the capacitor C1 effectively follows the conduction voltage drop V of the IGBT tube Q2. CE .

[0054] When the IGBT tube Q2 is turned on, the voltage drop V CE Increases, causing the voltage V across capacitor C1 to C1 When the voltage regulator ZD1 breaks down, the voltage regulator ZD1 breaks down; the voltage across the capacitor C1 minus the voltage of the voltage regulator ZD1 breakdown, the remaining voltage is divided by the resistors R5 and R6, and the reference voltage regulator U1 reference terminal voltage V REF When the value is greater than the set value (2.5V in the embodiment of the present application), the anode and cathode of the reference regulator U1 will be turned on; when the voltage on the resistor R6 is greater than the set value, the anode and cathode of the reference regulator U1 will be turned on, and the first voltage source VCC_DR (the first voltage source can be the driving voltage source of the IGBT tube Q2) passes through the anode and cathode of the optocoupler U2 and the resistor R7, and the collector and emitter of the optocoupler U2 are turned on, and the voltage output by the second voltage source VCC_MCU passes through the collector and emitter of the optocoupler U2 to establish a voltage on the resistor R10; thereby outputting the protection signal IGBT_SC, which is the blocking signal of the driving signal PWM_G2 of the IGBT tube. In circuit design, when the protection signal IGBT_SC is at a high level, the control device (such as MCU) will block the driving signal PWM_G2 of the IGBT, so as to quickly shut down the IGBT tube and stop the corresponding power circuit from working.

[0055] It should be noted that in the implementation mode of the present application, firstly, due to the existence of gate and Miller parasitic capacitance of the IGBT tube Q2, there is a delay time of 400nS-800nS during the opening process of the IGBT tube Q2, so the resistor R8 and the capacitor C1 are set with a charging time, and the charging time is designed to be greater than the conduction time of the IGBT tube to avoid false triggering of the protection signal IGBT_SC during the opening process of the IGBT tube.

[0056] Secondly, the purpose of designing capacitor C2 is to filter the voltage across resistor R6 to ensure that the reference voltage of reference regulator U1 is reliable and accurate and to avoid false triggering of protection signal IGBT_SC; resistor R10 is a pull-down resistor. When the collector and emitter of optocoupler U2 are turned on, a voltage is established on resistor R10. Capacitor C3 is a filter capacitor for protecting signal IGBT_SC.

[0057] Finally, after the IGBT tube Q2 is turned off, when the IGBT tube Q1 is turned on, the collector voltage of the IGBT tube Q2 is BUS+, and the desaturation detection and protection circuits are both low-voltage circuit devices and cannot withstand high voltage. Therefore, a diode D1 is designed. The diode D1 is selected as a high-voltage and low-current device, and a resistor R11 is added to the design. When the drive signal PWM_G2 is at a low level, the IGBT tube Q2 is turned off. When the diode D1 is in a reverse biased state, the voltage on the power tube Q2 is prevented from being transmitted to the detection drive module, thereby ensuring the safe operation of the subsequent circuit; at the same time, the drive signal PWM_G2 is at a low level to discharge the voltage across the capacitor C1 to 0V. When the next drive signal PWM_G2 is at a high level, the voltage of the capacitor C1 starts to rise from 0V to avoid erroneous triggering of the protection signal IGBT_SC during the IGBT tube opening process. Different from the prior art, the embodiment of the present invention outputs a driving voltage that follows the conduction voltage drop of the power tube when the driving signal is at a high level as a basis for judging whether the collector current exceeds the rated value; the detection driving module outputs a protection signal when the driving voltage is greater than or equal to the preset voltage to realize overcurrent detection and protection of the power tube; when the driving signal is at a low level, the overcurrent detection and protection of the power tube is stopped. The power consumption of the power tube desaturation protection circuit can be reduced, its reliability can be improved, and the hardware cost can be reduced.

[0058] Furthermore, another power tube desaturation protection circuit is provided, and its structural schematic diagram is shown in FIG. Figure 6 As shown, the power tube desaturation protection circuit includes a unidirectional conduction module 110 , a detection and driving module 120 , a delay module 130 and a discharge module 140 .

[0059] The output end of the one-way conduction module 110 is used to connect the power tube 30, the detection and driving module 120 is also connected to the input end of the one-way conduction module 110, the delay module 130 is connected to the input end of the one-way conduction module 110 and the detection and driving module 120, and the discharge module 140 is connected between the input end of the one-way conduction module and the driving signal source 20

[0060] It should be noted that the driving signal output by the driving signal source 20 and the signal driving the power tube 30 have the same control timing.

[0061] The detection drive module 120 is used to receive the drive voltage in response to the conduction voltage drop of the unidirectional conduction module 110 and the conduction voltage drop of the power tube 30 when the drive signal is at a high level, and output a protection signal when the drive voltage is greater than or equal to a preset voltage; when the drive signal is at a low level, the detection drive module 120 stops outputting the protection signal in response to the low-level drive signal.

[0062] When the driving signal is at a high level, the power tube 30 and the unidirectional conduction module 110 are used to transmit the voltage of the driving signal source to the detection driving module 120, and clamp it to the sum of the conduction voltage drop of the power tube 30 and the conduction voltage drop of the unidirectional conduction module 110, so that the detection driving module 120 receives the driving voltage; when the driving signal is at a low level, the detection driving module 120 responds to the driving voltage received by the low-level driving signal being less than the preset voltage, so as to stop outputting the protection signal; when the driving voltage is reduced to less than the preset voltage, the detection driving module stops outputting the protection signal. The driving voltage responds to the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module, that is, the driving voltage follows the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module; in other words, the driving voltage depends on the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module. As the most direct implementation method, the driving voltage is equal to the sum of the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module.

[0063] The delay module 130 is used to delay the detection drive module 120 to receive the drive voltage for a preset time under the action of a high-level drive signal; it should be emphasized that the preset time is greater than the conduction time of the power tube. It should be noted that the delay module 130 includes a capacitor C1. When the drive signal is at a high level, the high-level drive signal will charge the capacitor C1 to avoid a delay in the conduction of the power tube, which causes the high-level drive signal to be directly transmitted to the detection drive module and cause malfunction.

[0064] When the driving signal is at a low level, the discharge module 140 discharges the electric energy stored in the delay module 130 to ensure that the electric energy stored in the delay module is completely discharged before the next driving cycle starts, thereby ensuring that the delay module can work normally in the next driving cycle.

[0065] In some embodiments of the present application, Figure 6 The circuit schematic diagram of the power tube desaturation protection circuit is shown in Figure 7As shown, the application object is the lower arm IGBT tube Q2 of the half-bridge circuit. It should be noted that the power tube desaturation protection circuit can achieve the same function and effect in both the upper arm IGBT tube and the lower arm power IGBT tube. Among them, the detection unit 121 includes a voltage regulator diode ZD1, a resistor R5, a resistor R6, a resistor R7, a capacitor C2 and a reference regulator U1, and the driving unit 122 includes an optical coupler U2, a resistor R10 and a capacitor C3; the unidirectional conduction module 110 includes a diode D1, and the delay module 130 includes a capacitor C1 and a resistor R11; the discharge module 140 includes a diode D2, a resistor R8 and a resistor R9.

[0066] The cathode of the diode D1 is connected to the collector of the IGBT tube Q2, the cathode of the voltage regulator diode ZD1 is connected to the anode of the diode D1, the first end of the capacitor C1, the first end of the resistor R11, the anode of the diode D2 and the first end of the resistor R8, the cathode of the diode D2 is connected to the first end of the resistor R9, the second end of the resistor R9 is connected to the second end of the resistor R8 and the driving signal source to receive the driving signal PWM_G2; the anode of the voltage regulator diode ZD1 is connected to the first end of the resistor R5, the second end of the resistor R5 is connected to the first end of the resistor R6, the first end of the capacitor C2 and the reference end of the reference regulator U1, the cathode of the reference regulator U1 is connected to the second end of the resistor R7, the emitter of the IGBT tube Q2, the second end of the capacitor C1, the second end of the resistor R11, the anode of the reference regulator U1, the second end of the resistor R6 and the second end of the capacitor C2 are connected to the first reference ground GND_BUS.

[0067] The first end of the resistor R7 is connected to the cathode of the optocoupler U2, the anode of the optocoupler U2 is connected to the first voltage source VCC_DR, the collector of the optocoupler U2 is connected to the second voltage source VCC_MCU, the emitter of the optocoupler U2 is connected to the first end of the resistor R10 and the first end of the capacitor C3, the emitter of the optocoupler U2 is used to output the protection signal IGBT_SC, and the second end of the resistor R10 and the second end of the capacitor C3 are connected to the second reference ground GND_MCU.

[0068] Specifically, when the drive signal PWM_G2 is at a high level, the IGBT tube Q2 is turned on, the drive signal PWM_G2 charges the capacitor C1, and the IGBT tube Q2 is turned on; when the capacitor C1 is charged for a preset time and the voltage is higher than the conduction voltage drop V CE The forward voltage drop of diode D1 is V F After the sum, diode D1 is turned on; the voltage V across capacitor C1 C1 =V F +V CE That is, when the IGBT tube Q2 is turned on, the voltage across the capacitor C1 effectively follows the conduction voltage drop V of the IGBT tube Q2. CE .

[0069] When the IGBT tube Q2 is turned on, the voltage drop V CE Increases, causing the voltage V across capacitor C1 to C1 When the voltage regulator ZD1 breaks down, the voltage regulator ZD1 breaks down; the voltage across the capacitor C1 minus the voltage of the voltage regulator ZD1 breakdown, the remaining voltage is divided by the resistors R5 and R6, and the reference voltage regulator U1 reference terminal voltage V REF When the value is greater than the set value (2.5V in the embodiment of the present application), the anode and cathode of the reference regulator U1 will be turned on; when the voltage on the resistor R6 is greater than the set value, the anode and cathode of the reference regulator U1 will be turned on, and the first voltage source VCC_DR (the first voltage source can be the driving voltage source of the IGBT tube Q2) passes through the anode and cathode of the optocoupler U2 and the resistor R7, and the collector and emitter of the optocoupler U2 are turned on, and the voltage output by the second voltage source VCC_MCU passes through the collector and emitter of the optocoupler U2 to establish a voltage on the resistor R10; thereby outputting the protection signal IGBT_SC, which is the blocking signal of the driving signal PWM_G2 of the IGBT tube. In circuit design, when the protection signal IGBT_SC is at a high level, the control device (such as MCU) will block the driving signal PWM_G2 of the IGBT, so as to quickly shut down the IGBT tube and stop the corresponding power circuit from working.

[0070] It should be noted that in the design of the diode D2 and the resistor R9, the resistance of the resistor R9 is much smaller than the resistance of the resistor R8, so that when the drive signal PWM_G2 is at a low level, the charge in the capacitor C1 can be quickly discharged. To ensure the next drive cycle, when the drive signal PWM_G2 is at a high level, the IGBT tube Q2 starts charging the capacitor C1 from 0V within the turn-on delay time to avoid false triggering of the protection signal IGBT_SC.

[0071] Different from the prior art, the embodiment of the present invention outputs a driving voltage that follows the conduction voltage drop of the power tube when the driving signal is at a high level as a basis for judging whether the collector current exceeds the rated value; the detection driving module outputs a protection signal when the driving voltage is greater than or equal to the preset voltage to realize overcurrent detection and protection of the power tube; when the driving signal is at a low level, the overcurrent detection and protection of the power tube is stopped. The power consumption of the power tube desaturation protection circuit can be reduced, its reliability can be improved, and the hardware cost can be reduced.

[0072] Based on any power tube desaturation protection circuit provided in the above embodiments, an embodiment of the present invention provides an energy storage power supply, which includes a plurality of power tubes; and a plurality of power tube desaturation protection circuits as described in any of the above embodiments; one power tube is connected to one power tube desaturation protection circuit.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power tube desaturation protection circuit, characterized in that: include: A unidirectional conduction module and a detection and driving module, wherein the input end of the unidirectional conduction module is used to connect to a driving signal source, the output end of the unidirectional conduction module is used to connect to the power tube, and the detection and driving module is also connected to the input end of the unidirectional conduction module; wherein the driving signal output by the driving signal source has the same control timing as the signal driving the power tube; The detection driving module is used to receive the driving voltage in response to the conduction voltage drop of the unidirectional conduction module and the conduction voltage drop of the power tube when the driving signal is at a high level, and output a protection signal when the driving voltage is greater than or equal to a preset voltage; when the driving signal is at a low level, stop outputting the protection signal in response to the low-level driving signal; The detection drive module includes a detection unit and a drive unit. The detection unit includes a voltage regulator diode ZD1, a resistor R5, a resistor R6, a resistor R7, a capacitor C2 and a reference voltage regulator U1. The drive unit includes an optical coupler U2, a resistor R10 and a capacitor C3. The cathode of the voltage regulator diode ZD1 is connected to the input end of the unidirectional conduction module, the anode of the voltage regulator diode ZD1 is connected to the first end of the resistor R5, the second end of the resistor R5 is connected to the first end of the resistor R6, the first end of the capacitor C2 and the reference end of the reference regulator U1, the cathode of the reference regulator U1 is connected to the second end of the resistor R7, and the anode of the reference regulator U1, the second end of the resistor R6 and the second end of the capacitor C2 are connected to the first reference ground; The first end of the resistor R7 is connected to the cathode of the optocoupler U2, the anode of the optocoupler U2 is connected to the first voltage source, the collector of the optocoupler U2 is connected to the second voltage source, the emitter of the optocoupler U2 is connected to the first end of the resistor R10 and the first end of the capacitor C3, the emitter of the optocoupler U2 is used to output the protection signal, and the second end of the resistor R10 and the second end of the capacitor C3 are connected to the second reference ground.

2. The circuit according to claim 1, characterized in that When the driving voltage is less than the preset voltage, the detection driving module stops outputting the protection signal; the driving voltage responds to the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module.

3. The circuit according to claim 1, characterized in that When the driving signal is at a high level, the power tube and the unidirectional conduction module are used to clamp the voltage transmitted from the driving signal source to the detection driving module to the sum of the conduction voltage drop of the power tube and the conduction voltage drop of the unidirectional conduction module, so that the detection driving module receives the driving voltage; When the driving signal is at a low level, the detection driving module stops outputting the protection signal in response to the driving voltage received by the low-level driving signal being less than the preset voltage.

4. The circuit according to claim 1, characterized in that The driving signal is a signal for driving the power tube.

5. The circuit according to claim 1, characterized in that It also includes a delay module, which is connected to the input end of the one-way conduction module and the detection and driving module; The delay module is used to delay the detection drive module to receive the drive voltage for a preset time under the action of the high-level drive signal; the preset time is greater than the conduction time of the power tube.

6. The circuit according to claim 5, characterized in that It also includes a discharge module, which is connected between the input end of the unidirectional conduction module and the driving signal source; The discharge module discharges the electric energy stored in the delay module when the driving signal is at a low level.

7. The circuit according to claim 6, characterized in that The discharge module includes a diode D2, a resistor R8 and a resistor R9. The anode of the diode D2 is connected to the input end of the unidirectional conduction module and the first end of the resistor R8, the cathode of the diode D2 is connected to the first end of the resistor R9, and the second end of the resistor R9 is connected to the second end of the resistor R8 and the driving signal source.

8. An energy storage power supply, characterized in that: A number of power tubes; and A plurality of power tube desaturation protection circuits as described in any one of claims 1 to 7; one power tube is connected to one power tube desaturation protection circuit.

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