Overcurrent protection circuit, power converter and power distribution loop

Abstract

The utility model discloses an overcurrent protection circuit, a power converter and a power distribution loop, and relates to the technical field of power electronics. According to the overcurrent protection circuit, the magnitude of current flowing through the protected loop is detected through the current detection unit, and a corresponding current detection signal is generated and output to the overcurrent protection unit; the overcurrent protection unit can control the driving unit to output a driving signal to a switch control end in the protected loop according to the magnitude of the current in the protected loop; moreover, when the current detection signal is greater than a preset overload current threshold signal, that is, the protected loop is overloaded or even short-circuited, the driving signal controls the switch to be switched off, so that the protected loop is cut off, and the protection of corresponding circuit elements is realized. The problems that existing short-circuit protection is high in cost and existing overload protection consumes long time can be solved, and the method can be suitable for a power converter circuit controlled by PWM and can also be suitable for a power distribution loop controlled by GPIO and the like.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to an overcurrent protection circuit, a power converter, and a power distribution circuit. Background Art

[0002] An overcurrent protection circuit is designed to protect circuit components by disconnecting the circuit breaker when the circuit current exceeds a predetermined maximum value. This circuit is also known as an overcurrent protection (OCP) circuit. OCP includes short-circuit protection and overload protection. Existing solutions typically use dedicated desaturation (desaturation) chips for short-circuit protection and current sampling combined with software-based judgment for overload protection. However, these dedicated chips are expensive, and the software judgment process is time-consuming. Utility Model Content

[0003] In view of the above problems, this application provides an overcurrent protection circuit, a power converter, and a power distribution circuit to avoid the high cost of short-circuit protection and the long time-consuming overload protection in the prior art. The specific solution is as follows:

[0004] The first aspect of the present application provides an overcurrent protection circuit, comprising: a driving unit, a current detection unit, and an overcurrent protection unit; wherein,

[0005] The input end of the current detection unit is connected to the two ends of the current detection resistor in the protected circuit;

[0006] The output end of the current detection unit is connected to the input end of the overcurrent protection unit and outputs a current detection signal;

[0007] The output end of the overcurrent protection unit is connected to the control end of the driving unit;

[0008] The input end of the driving unit receives a control signal of a switch in the protected circuit;

[0009] The output end of the driving unit is connected to the control end of the switch and outputs a driving signal;

[0010] When the current detection signal is greater than a preset overload current threshold signal, the driving signal is a signal for controlling the switch to be disconnected.

[0011] In a possible implementation, the driving unit includes: a driving chip and a switch tube;

[0012] The positive input terminal of the driver chip is connected to the input terminal of the driver unit, and the switch tube is connected between the negative input terminal of the driver chip and the reference ground; or the switch tube is connected between the input terminal of the driver unit and the positive input terminal of the driver chip, and the negative input terminal of the driver chip is connected to the reference ground;

[0013] The output end of the driving chip is connected to the output end of the driving unit;

[0014] The control end of the switch tube is connected to the control end of the drive unit.

[0015] In a possible implementation, the driver chip is an optocoupler driver chip, the primary positive electrode of the optocoupler driver chip serves as the positive input terminal of the driver chip, and the primary negative electrode of the optocoupler driver chip serves as the negative input terminal of the driver chip.

[0016] In a possible implementation, the output end of the driving chip is connected to the output end of the driving unit through a first resistor;

[0017] The control end of the switch tube is connected to the control end of the drive unit through a second resistor.

[0018] In a possible implementation, the overcurrent protection unit includes: a comparison unit;

[0019] An input terminal of the comparison unit is connected to an input terminal of the overcurrent protection unit;

[0020] Another input terminal of the comparison unit receives the preset overload current threshold signal;

[0021] The output end of the comparison unit is connected to the output end of the overcurrent protection unit.

[0022] In a possible implementation, the overcurrent protection unit further includes: a latch unit;

[0023] The input end of the latch unit is connected to the output end of the comparison unit;

[0024] The output end of the latch unit is connected to the output end of the overcurrent protection unit.

[0025] In a possible implementation, the current detection unit includes: an isolation operational amplifier circuit and a conditioning circuit;

[0026] The input end of the isolation operational amplifier circuit is connected to the input end of the current detection unit;

[0027] The output end of the isolation operational amplifier circuit is connected to the input end of the conditioning circuit;

[0028] The output end of the conditioning circuit is connected to the output end of the current detection unit.

[0029] In a possible implementation, the current detection unit further includes: a filter circuit;

[0030] The input end of the filter circuit is connected to the input end of the current detection unit;

[0031] The output end of the filter circuit is connected to the input end of the isolation operational amplifier circuit.

[0032] In a possible implementation, the filtering circuit includes: a third resistor, a fourth resistor, and a capacitor;

[0033] One end of the third resistor and one end of the fourth resistor serve as input ends of the filter circuit;

[0034] The other end of the third resistor and the other end of the fourth resistor are respectively connected to the two ends of the capacitor and serve as output ends of the filter circuit.

[0035] The second aspect of the present application provides a power converter, comprising: a controller and a main circuit; wherein,

[0036] The main circuit includes at least one switching tube;

[0037] The switch tube is equipped with a corresponding current-sense resistor and an overcurrent protection circuit;

[0038] The overcurrent protection circuit is the overcurrent protection circuit as described in the first aspect or any implementation form of the first aspect above;

[0039] The switch tube serves as a switch in the protected circuit and receives the control signal output by the controller through the corresponding overcurrent protection circuit.

[0040] A third aspect of the present application provides a power distribution circuit, comprising: a switch, a current sensing resistor, and the overcurrent protection circuit as described in the first aspect or any implementation form of the first aspect; wherein,

[0041] The switch is provided in the positive transmission branch or the negative transmission branch of the power distribution circuit;

[0042] The current-sensing resistor is arranged in the positive transmission branch or the negative transmission branch;

[0043] The switch serves as a switch in the protected circuit and receives a control signal through the overcurrent protection circuit.

[0044] By means of the above technical solution, the overcurrent protection circuit provided by the present application has a current detection unit connected to the two ends of the current detection resistor in the protected circuit through its own input end, so that the current detection unit can detect the current flowing through the protected circuit and generate a corresponding current detection signal; the output end of the current detection unit outputs the current detection signal and is connected to the control end of the drive unit through the overcurrent protection unit, so that the overcurrent protection unit can control the drive signal output by the drive unit to the switch control end in the protected circuit according to the current in the protected circuit; and when the current detection signal is greater than the preset overload current threshold signal, that is, when the protected circuit is overloaded or even short-circuited, the drive signal will control the switch to disconnect, thereby cutting off the protected circuit and protecting the corresponding circuit elements. The present application can achieve short-circuit protection and overload protection for the protected circuit through the above process, without the need for a dedicated chip, which can avoid the high cost of existing short-circuit protection; and, without the need for any software judgment process of the control unit, which can avoid the time-consuming problem of existing overload protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and other features, advantages, and aspects of the various embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and that the originals and elements are not necessarily drawn to scale.

[0046] Figure 1 A schematic diagram of the structure of an overcurrent protection circuit and its connection relationship with a power distribution circuit provided in an embodiment of the present application;

[0047] Figure 2 A schematic structural diagram of a driving unit in an overcurrent protection circuit provided in an embodiment of the present application;

[0048] Figure 3 Another structural schematic diagram of a driving unit in the overcurrent protection circuit provided in an embodiment of the present application;

[0049] Figure 4 A schematic structural diagram of a current detection unit in an overcurrent protection circuit provided in an embodiment of the present application;

[0050] Figure 5 Another structural schematic diagram of a current detection unit in the overcurrent protection circuit provided in an embodiment of the present application;

[0051] Figure 6 A schematic structural diagram of an overcurrent protection unit in an overcurrent protection circuit provided in an embodiment of the present application;

[0052] Figure 7Another structural diagram of an overcurrent protection unit in the overcurrent protection circuit provided in an embodiment of the present application;

[0053] Figure 8 A schematic structural diagram of a power converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0054] The following describes the embodiments of the present application in conjunction with the accompanying drawings. The terms used in the implementation methods of the present application are only used to explain the specific embodiments of the present application and are not intended to limit the present application.

[0055] The embodiments of the present application are described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. It is known to those of ordinary skill in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0056] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, and this is merely a way of distinguishing the objects of the same attributes when describing them in the embodiments of the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0057] When overcurrent protection is performed on circuit components, since the short-circuit current can reach dozens to dozens of times the rated current, while the overload current is generally only several times the rated current, short-circuit protection usually has relatively high requirements. Common short-circuit protection includes DESATS protection suitable for inverter bridges, which achieves µs-level protection through the characteristics of the switching tubes used in the inverter bridge, such as IGBTs (Insulated Gate Bipolar Transistors), that is, the rapid increase in their conduction voltage drop under large currents. Dedicated DESATS chips, that is, driver chips with integrated DESATS monitoring functions, identify the above characteristics when a short circuit occurs and perform internal blocking, that is, blocking the DESATS chip's drive signal to the IGBT, controlling the IGBT to disconnect, and thus achieving short-circuit protection. However, this dedicated DESATS chip is relatively expensive and can only protect against short-circuit and high-current conditions.

[0058] Overload protection generally uses a current sensor or sampling resistor to convert the loop current into a voltage analog value. This voltage analog value is then conditioned by an op amp and sent to a control unit such as a DSP (Digital Signal Processor). The DSP then performs a logical judgment and, upon determining that an overload has occurred, issues a command to disconnect the switch in the control loop. Because this process requires software judgment, the duration of overload protection is generally tens to hundreds of microseconds and can generally only be used for overload protection. In other words, existing overload protection solutions, due to the long software processing and judgment time, run the risk of failing to provide timely protection.

[0059] In the above-mentioned overload protection scheme, if the voltage analog value is judged by a hardware comparator and then sent to the DSP's TZ (Trip Zone, fault capture submodule) for rapid wave sealing processing, the circuit can also be protected at a speed of us. However, the wave sealing processing after hardware judgment is limited by the specific nature of TZ, that is, it can only be used for PWM (Pulse Width Modulation) drive modules. It is applicable to bridge circuits such as inverters. For more application scenarios, such as using GPIO (General Purpose Input Output) signals to control IGBTs to control the on and off of distribution circuits, and the distribution circuits also require overload protection and us-level fast short-circuit protection, this traditional hardware processing method is not applicable.

[0060] Therefore, the embodiment of the present application provides an overcurrent protection circuit to avoid the problems of high cost of short-circuit protection and long time-consuming overload protection in the prior art, and can also be applied to various scenarios. The specific scheme is as follows:

[0061] See also Figure 1 The overcurrent protection circuit includes: a driving unit 10, a current detection unit 20 and an overcurrent protection unit 30; wherein:

[0062] An input end of the current detection unit 20 is connected to both ends of the current detection resistor R_cy in the protected circuit. Figure 1 Taking the power distribution circuit controlled by GPIO signal as an example, the power distribution circuit is used as the protected circuit, and its transmission branch is provided with a switch tube Q1 and a current detection resistor R_cy connected in series; the switch tube Q1 serves as the switch in the protected circuit and is controlled by the GPIO signal; and Figure 1The power distribution circuit shown in the figure is specifically a new energy high-voltage power distribution circuit that transmits the high-voltage electric energy provided by the power battery in the new energy vehicle to the load. The high-voltage electric energy here is relative to the low-voltage electric energy used by the low-voltage battery and low-voltage electrical equipment in the new energy vehicle. In addition, the protected circuit can also refer to the circuit where the switch tube controlled by the PWM signal is located. The circuit structure where the switch tube is located can be determined according to the actual situation. For example, the circuit structure of various power converters in the prior art is within the protection scope of this application; when each switch tube in the circuit is turned on, the circuit where it is located can be used as a protected circuit, that is, at least one corresponding current detection resistor can be provided in the protected circuit, and at least one switch tube can be provided as a switch in the protected circuit, and each switch uses the overcurrent protection circuit provided in this embodiment for overcurrent protection. It should be noted that, Figure 1 The connection relationship between the switch tube Q1 and the current-sense resistor R_cy is only exemplarily shown. In actual applications, the positions of the two are not limited, as long as the two are connected in series in the protected circuit.

[0063] The output terminal of the current detection unit 20 is connected to the input terminal of the overcurrent protection unit 30 and outputs a current detection signal I_sense. The current detection signal I_sense is used to represent the current flowing through the current sensing resistor R_cy, that is, the current in the protected circuit.

[0064] The output end of the overcurrent protection unit 30 is connected to the control end of the drive unit 10; the overcurrent protection unit 30 is used to implement the judgment function of the above-mentioned hardware comparator, that is, to compare the current detection signal I_sense with the preset overload current threshold signal V_ref; if the current detection signal I_sense is greater than the preset overload current threshold signal V_ref, it means that the protected circuit is currently overloaded or even short-circuited, and a corresponding signal can be output to the control end of the drive unit 10.

[0065] The input terminal of the driving unit 10 receives the switch in the protected circuit (such as Figure 1 The control signal IN of the switch tube Q1 shown in FIG. 1 is derived from a control unit, which may be a controller of the circuit structure in which the switch is located, but is not limited here. The output end of the drive unit 10 is connected to the control end of the switch and outputs a drive signal. Under normal circumstances, the drive unit 10 generates a corresponding drive signal based on the control signal IN of the switch, thereby controlling the operation of the switch. However, when the current detection signal I_sense is greater than the preset overload current threshold signal V_ref, that is, when the protected circuit is currently overloaded or even short-circuited, the drive signal will be switched to a signal that controls the disconnection of the switch, thereby disconnecting the protected circuit and achieving corresponding protection for each circuit element in the protected circuit.

[0066] The overcurrent protection circuit provided by this application can achieve short-circuit protection and overload protection for the protected circuit through the above process, without the need for a dedicated desat chip, which can avoid the high cost of existing short-circuit protection. Furthermore, it does not require any control unit software judgment process, which can avoid the time-consuming problem of existing overload protection. In addition, this application does not limit the use scenario. For example, the switch can be a switch controlled by a PWM signal or a switch controlled by a GPIO signal, and the corresponding protection can be achieved through the above principle. That is, the applicable circuits of this overcurrent protection circuit include power converter circuits controlled by PWM, as well as power distribution circuits controlled by GPIO, and have strong applicability.

[0067] Based on the previous embodiment, this embodiment provides some exemplary explanations of the specific structure of the overcurrent protection circuit, such as:

[0068] (1) See Figure 2 or Figure 3 , the driving unit 10 may include: a driving chip 101 and a switch tube Q2.

[0069] like Figure 2 As shown in , the positive input terminal of the driver chip 101 is connected to the input terminal of the driver unit 10 to receive the control signal IN; the switch tube Q2 is connected between the negative input terminal of the driver chip 101 and the reference ground. Or, as Figure 3 As shown in FIG, the switch Q2 is connected between the input terminal of the driver unit 10 and the positive input terminal of the driver chip 101, and the negative input terminal of the driver chip 101 is connected to the reference ground. In other words, as long as the switch Q2 is present in the path of the control signal IN passing through the input terminal of the driver chip 101, its specific location is not limited and is within the scope of protection of this application.

[0070] The output terminal of the driver chip 101 is connected to the output terminal of the driver unit 10, and outputs a driving signal for the switch in the protected circuit. Figure 2 and Figure 3 All in Figure 1 The structure shown is shown as an example, wherein the switch tube Q1 is the switch in the protected circuit, the battery + is Figure 1 The positive electrode of the power battery, R_cy-1 refers to Figure 1 The middle current-sense resistor R_cy is used to connect one end of the switch tube Q1.

[0071] The control end of the switch tube Q2 is connected to the control end of the driving unit 10 and receives the on-off control signal Q_G of the switch tube Q2.

[0072] In practical applications, the driver chip 101 can be implemented as an optocoupler driver chip, which can achieve isolated drive of the switch and improve safety. In this case, the primary positive electrode A of the optocoupler driver chip serves as the positive input terminal of the driver chip 101, and the primary negative electrode C of the optocoupler driver chip serves as the negative input terminal of the driver chip 101.

[0073] The switch tube Q2 is a semiconductor device, which can specifically be a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or a BJT (Bipolar Junction Transistor), etc., which is not limited here. It can be used for signal transmission in low-voltage scenarios. Other switch tubes in the prior art are also within the protection scope of this application.

[0074] In addition, in order to achieve driving current limiting for each switching tube, corresponding driving resistors can be set for the switching tube Q2 and the switching tube Q1 serving as a switch in the driving unit 10, that is, the output end of the driving chip 101 can be connected to the output end of the driving unit 10 through the first resistor R1; and the control end of the switching tube Q2 can be connected to the control end of the driving unit 10 through the second resistor R2.

[0075] by Figure 2The operating principle of the driver unit 10 is explained using the illustrated structure as an example: the control unit outputs the control signal IN through its own GPIO port to the primary positive electrode A of the optocoupler driver chip. The primary negative electrode C of the optocoupler driver chip is connected to the reference ground via the switch Q2. Under normal operating conditions, the on-off control signal Q_G controls the switch Q2 to conduct, forming a path between the primary negative electrode C of the optocoupler driver chip and the reference ground. In this case, the drive signal received by the control terminal of the switch Q1 is controlled by the level of the control signal IN. Specifically, when the control signal IN is high, the output signal Vo of the driver chip 101 is a positive voltage, which in turn causes the drive signal received by the control terminal of the switch Q1 to also be a positive voltage, causing it to conduct, thereby turning on the protected circuit. When the control signal IN is low, the output signal Vo of the driver chip 101 is a negative voltage, which in turn causes the drive signal received by the control terminal of the switch Q1 to also be a negative voltage, thereby turning it into a blocking state, thereby disconnecting the protected circuit. When the protected circuit is overloaded or short-circuited, the on-off control signal Q_G controls the switch tube Q2 to turn off, thereby cutting off the path between the primary negative electrode C of the optocoupler driver chip and the reference ground. In this case, regardless of the level of the control signal IN, the optocoupler driver chip can no longer output a corresponding drive signal to the switch tube Q1, thereby keeping the switch tube Q1 in the off state, cutting off the protected circuit and protecting the corresponding circuit components.

[0076] (2) Figure 4 An optional structure of the current detection unit 20 is shown, which specifically includes: an isolation operational amplifier circuit 201 and a conditioning circuit 202; wherein, the input end of the isolation operational amplifier circuit 201 is connected to the input end of the current detection unit 20; the output end of the isolation operational amplifier circuit 201 is connected to the input end of the conditioning circuit 202; and the output end of the conditioning circuit 202 is connected to the output end of the current detection unit 20. Figure 4 Also in Figure 1 The structure shown is illustrated as an example, wherein Q1-E represents the emitter of the switch Q1 and LOAD+ represents the positive electrode of the load. The isolation operational amplifier circuit 201 and the conditioning circuit 202 can respectively adopt corresponding circuits in the prior art, which will not be described in detail here.

[0077] In practical applications, the current detection unit 20 may further include Figure 5 As shown in: filter circuit 203; the input end of the filter circuit 203 is connected to the input end of the current detection unit 20; the output end of the filter circuit 203 is connected to the input end of the isolation amplifier circuit 201. Figure 5As shown in the figure, the filter circuit 203 includes: a third resistor R3, a fourth resistor R4 and a capacitor C; one end of the third resistor R3 and one end of the fourth resistor R4 serve as input ends of the filter circuit 203; the other end of the third resistor R3 and the other end of the fourth resistor R4 are respectively connected to the two ends of the capacitor C and serve as output ends of the filter circuit 203.

[0078] by Figure 5 Taking the structure shown as an example, the working principle of the current detection unit 20 is explained: when there is current in the protected circuit, that is, when current flows through the current detection resistor R_cy, a corresponding voltage will be generated at both ends of the current detection resistor R_cy. This voltage signal is filtered by the filter circuit 203 and input into the isolation operational amplifier circuit 201; the filtered voltage signal is processed by the isolation operational amplifier circuit 201 and output as the input of the conditioning circuit 202; the conditioning circuit 202 amplifies the voltage signal input to itself or increases the bias, and conditions the voltage signal output by the isolation operational amplifier circuit 201 into an analog quantity with a suitable amplitude, that is, the above-mentioned current detection signal I_sense, and then inputs it into the overcurrent protection unit 30.

[0079] (3) Figure 6 An optional structure of the overcurrent protection unit 30 is shown, which specifically includes a comparison unit 301; one input terminal of the comparison unit 301 is connected to the input terminal of the overcurrent protection unit 30 and receives the current detection signal I_sense; another input terminal of the comparison unit 301 receives the preset overload current threshold signal V_ref; and an output terminal of the comparison unit 301 is connected to the output terminal of the overcurrent protection unit 30 and outputs the on / off control signal Q_G. In practical applications, the comparison unit 301 can be implemented using a comparator.

[0080] In this structure, the comparison unit 301 compares the current detection signal I_sense with a preset overload current threshold signal V_ref. If the current detection signal I_sense is greater than the preset overload current threshold signal V_ref, it indicates that the protected circuit is currently overloaded or even short-circuited, and the output on / off control signal G_Q controls the switch Q2 in the driver unit 10 to turn off. The specific value of the preset overload current threshold signal V_ref is not limited and can be customized based on the specifications of the circuit components in the protected circuit. As long as the current detection signal I_sense is greater than the preset overload current threshold signal V_ref, it can be used to indicate that the protected circuit is currently overloaded.

[0081] In practical applications, the overcurrent protection unit 30 may further include Figure 7As shown in FIG: a latch unit 302; an input end of the latch unit 302 is connected to the output end of the comparison unit 301; and an output end of the latch unit 302 is connected to the output end of the overcurrent protection unit 30. The latch unit 302 can be implemented using a latch chip or a hardware circuit, both of which are within the scope of protection of this application.

[0082] Figure 7 In the structure shown, the current detection signal I_sense is compared with the preset overload current threshold signal V_ref, the output result of the comparison unit 301 is used as the input of the latch unit 302, and the output signal of the latch unit 302 is used as the on-off control signal Q_G of the switch tube Q2 in the driving unit 10.

[0083] The following combination Figure 1 、 Figure 2 、 Figure 5 and Figure 7 , a complete description of the working principle of the overcurrent protection circuit is given below:

[0084] In the initial state, the comparison unit 301 outputs a high level by default. The on / off control signal Q_G obtained after the latch unit 302 is also high, making the default state of the switch Q2 on. After the system receives the instruction to control the power distribution circuit to close, the GPIO signal output by the control unit (i.e., the control signal IN) is a constant high level. This signal is transmitted to the positive input terminal A of the optocoupler driver chip. Since the switch Q2 is in the on state at this time, the output signal Vo of the optocoupler driver chip is high after receiving power, thereby controlling the switch Q1 to conduct, completing the power distribution requirement.

[0085] When the load at the back end of the power distribution loop is short-circuited or overloaded, the loop current exceeds the preset overload current threshold signal V_ref. At this time, the output result of the comparison unit 301 is flipped, and the on-off control signal Q_G output by the latch unit 302 is synchronously flipped to a low level, controlling the switch tube Q2 to be disconnected; at this time, the primary side of the optocoupler driver chip loses voltage, and the control signal Vo output by the optocoupler driver chip is a low level, controlling the switch tube Q1 to be disconnected.

[0086] Furthermore, due to the presence of latch unit 302, after switch Q1 is turned off, the loop current returns to zero, but the on / off control signal Q_G remains at a low level. Once the back-end fault is resolved, a reset signal can be used to flip the level of the reset pin configured for latch unit 302, thereby resetting the output state of latch unit 302 from a faulty state to a normal state. Alternatively, the output state of latch unit 302 can be reset by cycling power, that is, by re-opening and re-closing the system's low-voltage power supply, causing all components or chips within the system to undergo a power-off and power-on cycle.

[0087] Based on the above, the overcurrent protection circuit, through the use of comparison unit 301 and latch unit 302, can quickly protect against overload and short-circuit conditions. Furthermore, the entire circuit achieves overcurrent protection through hardware connections alone. The circuit structure is simple and reliable, and it does not rely on the fast protection function of the driver chip, resulting in low cost. Furthermore, it can complete overload or short-circuit protection with low latency, resulting in high reliability. Furthermore, it is not limited to circuits using PWM drive modules, thus having a wide range of applications.

[0088] Another embodiment of the present application further provides a power converter, such as Figure 8 As shown in FIG, the present invention comprises: a controller 01 and a main circuit 02; the main circuit 02 may include at least one of the following circuits: a DC / DC conversion circuit, a DC / AC conversion circuit, an AC / DC conversion circuit, and an AC / AC conversion circuit, and its specific structure may adopt any topology in the prior art. Figure 8 In the example, an H-bridge circuit is used for demonstration. As long as the main circuit 02 includes at least one switching tube, the switching tube is equipped with a corresponding current-sense resistor and an overcurrent protection circuit. The overcurrent protection circuit is an overcurrent protection circuit as described in any of the above embodiments. Its structure and working principle can be found in the above embodiments and will not be described again here. The switching tube serves as a switch in the protected circuit and receives the control signal IN output by the controller through the corresponding overcurrent protection circuit.

[0089] In practical applications, the control signal IN may be a PWM signal.

[0090] It should be noted that the number of switches in the main circuit 02 is likely to be greater than 1. Figure 8The figure shows the situation of four switching tubes, among which switching tubes S1 and S4 are turned on and off at the same time, and switching tubes S2 and S3 are turned on and off at the same time; therefore, when switching tubes S1 and S4 are turned on, they are in the same circuit and can share the same current-sense resistor R2_cy; when switching tubes S2 and S3 are turned on, they are in the same circuit and can share the same current-sense resistor R1_cy. Switching tube S1 receives the control signal IN1 output by controller 01 through overcurrent protection circuit 1. Overcurrent protection circuit 1 detects the voltage V2 on both sides of current-sense resistor R2_cy, and generates a corresponding drive signal based on the voltage V2 and control signal IN1, which is sent to the control end of switching tube S1; switching tube S2 receives the control signal IN2 output by controller 01 through overcurrent protection circuit 2. Overcurrent protection circuit 2 detects the voltage V1 on both sides of current-sense resistor R1_cy, and generates a corresponding drive signal based on the voltage V1 and control signal IN2, which is sent to the control end of switching tube S2; Switch S3 receives a control signal IN3 output by controller 01 via overcurrent protection circuit 3. Overcurrent protection circuit 3 detects the voltage V1 across current-sense resistor R1_cy and generates a corresponding drive signal based on this voltage V1 and control signal IN3, which is sent to the control terminal of switch S3. Switch S4 receives a control signal IN4 output by controller 01 via overcurrent protection circuit 4. Overcurrent protection circuit 4 detects the voltage V2 across current-sense resistor R2_cy and generates a corresponding drive signal based on this voltage V2 and control signal IN4, which is sent to the control terminal of switch S4. Overcurrent protection circuits 1 through 4 are all overcurrent protection circuits described in the above embodiments. Their structures and operating principles can be found in the above embodiments and will not be further described here. In actual applications, switches S1 and S4 can also share the same overcurrent protection circuit because they are both turned on and off, and can also be equipped with a corresponding current-sense resistor. The same applies to switches S2 and S3, depending on their specific application environment and not limited here.

[0091] When the main circuit 02 adopts other topologies, each switching tube can be equipped with a corresponding overcurrent protection circuit and current sensing resistor respectively, or they can share a current sensing resistor because they are in the same circuit, or they can share an overcurrent protection circuit because they are opened and closed at the same time, depending on the specific application environment, all of which are within the protection scope of this application.

[0092] By employing the overcurrent protection circuit described in the above embodiment, at any point during the operation of the main circuit, the circuit currently carrying current serves as the protected circuit. If a short circuit or overload condition occurs, the circuit load can be rapidly disconnected, protecting the semiconductor device. Furthermore, the circuit structure is simple and reliable, with low cost, high speed, and high reliability.

[0093] Another embodiment of the present application further provides a power distribution circuit, such as Figure 1As shown in , it includes: a switch (such as the switch tube Q1 shown in the figure), a current sensing resistor R_cy and an overcurrent protection circuit as described in any of the above embodiments; the structure and working principle of the overcurrent protection circuit can be referred to the above embodiments and will not be repeated here; the switch is arranged in the positive transmission branch or the negative transmission branch of the power distribution circuit; the current sensing resistor R_cy is arranged in the positive transmission branch or the negative transmission branch; as Figure 1 As shown in FIG, the switch and the current-sense resistor R_cy are connected in series in the positive transmission branch. In practical applications, as long as both are located in the power distribution circuit and the current flowing through them is the same as the current in the power distribution circuit at the same time, they are all within the protection scope of this application. The switch serves as a switch in the protected circuit and receives the control signal IN through the overcurrent protection circuit.

[0094] In practical applications, the control signal IN is a GPIO signal.

[0095] Figure 1 Taking the use of an electronic switch (i.e., the switch tube Q1) instead of a contactor in the high-voltage distribution circuit of a new energy vehicle as an example, the switch tube Q1 can be a semiconductor device such as an IGBT, a MOSFET or a BJT, which is not limited here and depends on its specific application environment. The following is an explanation using the IGBT as an example: the positive electrode of the power battery is first connected to its collector, and its emitter is connected to one end of the current-sense resistor R_cy, and the other end of the current-sense resistor R_cy is connected to the positive electrode of the load; the negative electrode of the power battery is directly connected to the negative electrode of the load.

[0096] By adopting the overcurrent protection circuit described in the above embodiment, when a short circuit or overload condition occurs in the power distribution circuit, the circuit load can be disconnected extremely quickly to protect the semiconductor device. Moreover, the circuit structure is simple and reliable, the cost is low, and the speed is fast and the reliability is high.

[0097] The same or similar parts between the various embodiments in this specification can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Ordinary technicians in this field can understand and implement it without making any creative efforts.

[0098] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0099] With respect to the above description of the disclosed embodiments, the features described in the various embodiments in this specification may be interchanged or combined to enable those skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An overcurrent protection circuit, characterized in that: include: drive unit, current detection unit and overcurrent protection unit; wherein, The input end of the current detection unit is connected to the two ends of the current detection resistor in the protected circuit; The output end of the current detection unit is connected to the input end of the overcurrent protection unit and outputs a current detection signal; The output end of the overcurrent protection unit is connected to the control end of the driving unit; The input end of the driving unit receives a control signal of a switch in the protected circuit; The output end of the driving unit is connected to the control end of the switch and outputs a driving signal; When the current detection signal is greater than a preset overload current threshold signal, the driving signal is a signal for controlling the switch to be disconnected.

2. The overcurrent protection circuit according to claim 1, characterized in that: The driving unit includes: a driving chip and a switching tube; The positive input terminal of the driver chip is connected to the input terminal of the driver unit, and the switch tube is connected between the negative input terminal of the driver chip and the reference ground; or the switch tube is connected between the input terminal of the driver unit and the positive input terminal of the driver chip, and the negative input terminal of the driver chip is connected to the reference ground; The output end of the driving chip is connected to the output end of the driving unit; The control end of the switch tube is connected to the control end of the drive unit.

3. The overcurrent protection circuit according to claim 2, wherein: The driver chip is an optocoupler driver chip, the primary positive electrode of the optocoupler driver chip serves as the positive input terminal of the driver chip, and the primary negative electrode of the optocoupler driver chip serves as the negative input terminal of the driver chip.

4. The overcurrent protection circuit according to claim 2, wherein: The output end of the driving chip is connected to the output end of the driving unit through a first resistor; The control end of the switch tube is connected to the control end of the drive unit through a second resistor.

5. The overcurrent protection circuit according to claim 1, wherein: The overcurrent protection unit includes: a comparison unit; An input terminal of the comparison unit is connected to an input terminal of the overcurrent protection unit; Another input terminal of the comparison unit receives the preset overload current threshold signal; The output end of the comparison unit is connected to the output end of the overcurrent protection unit.

6. The overcurrent protection circuit according to claim 5, characterized in that: The overcurrent protection unit further includes: a latch unit; The input end of the latch unit is connected to the output end of the comparison unit; The output end of the latch unit is connected to the output end of the overcurrent protection unit.

7. The overcurrent protection circuit according to any one of claims 1 to 6, characterized in that: The current detection unit includes: an isolation operational amplifier circuit and a conditioning circuit; The input end of the isolation operational amplifier circuit is connected to the input end of the current detection unit; The output end of the isolation operational amplifier circuit is connected to the input end of the conditioning circuit; The output end of the conditioning circuit is connected to the output end of the current detection unit.

8. The overcurrent protection circuit according to claim 7, characterized in that: The current detection unit further includes: a filter circuit; The input end of the filter circuit is connected to the input end of the current detection unit; The output end of the filter circuit is connected to the input end of the isolation operational amplifier circuit.

9. The overcurrent protection circuit according to claim 8, characterized in that: The filtering circuit includes: a third resistor, a fourth resistor and a capacitor; One end of the third resistor and one end of the fourth resistor serve as input ends of the filter circuit; The other end of the third resistor and the other end of the fourth resistor are respectively connected to the two ends of the capacitor and serve as output ends of the filter circuit.

10. A power converter, characterized in that: include: Controller and main circuit; wherein, The main circuit includes at least one switching tube; The switch tube is equipped with a corresponding current-sense resistor and an overcurrent protection circuit; The overcurrent protection circuit is the overcurrent protection circuit according to any one of claims 1 to 9; The switch tube serves as a switch in the protected circuit and receives the control signal output by the controller through the corresponding overcurrent protection circuit.

11. A power distribution circuit, characterized in that: include: A switch, a current-sense resistor, and an overcurrent protection circuit as claimed in any one of claims 1 to 9; wherein, The switch is provided in the positive transmission branch or the negative transmission branch of the power distribution circuit; The current-sensing resistor is arranged in the positive transmission branch or the negative transmission branch; The switch serves as a switch in the protected circuit and receives a control signal through the overcurrent protection circuit.

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