Overcurrent protection circuit

Abstract

The utility model relates to an overcurrent protection circuit. The circuit comprises a power supply sub-circuit, a logic control sub-circuit, a first driving sub-circuit, a second driving sub-circuit, an output current sampling sub-circuit and a hysteresis comparison sub-circuit, the output end of the logic control sub-circuit is connected with the input end of the first driving sub-circuit; the output end of the first driving sub-circuit is connected with the input end of the second driving sub-circuit; the output end of the second driving sub-circuit is connected with the output current sampling sub-circuit; the output end of the output current sampling sub-circuit is connected with the hysteresis comparison sub-circuit; the output end of the hysteresis comparison sub-circuit is connected with the input end of the logic control sub-circuit; the protection circuit can restart a protected object after overcurrent protection without additionally arranging a reset circuit, the space of a printed circuit board is saved, the implementation cost is reduced, the hysteresis comparison circuit limits an overcurrent protection point within two threshold values, the circuit is prevented from being repeatedly opened and closed due to interference of external factors such as noise, and the reliability of the circuit is improved. And the stability and the anti-interference capability of the system are improved.

Description

Technical Field

[0001] The present application relates to the technical field of motor drive overcurrent protection, and in particular to an overcurrent protection circuit. Background Art

[0002] With the development of motor technology and motor drivers, more and more motor drivers are required to have overcurrent protection functions. Generally, brushless motors work by using several semiconductor power devices such as MOS tubes and CMOS tubes to build a three-phase bridge circuit with different switch combinations to generate sinusoidal currents with a phase difference of 120 degrees. When the brushless motor is running, the three-phase line current may increase due to its own fault or improper controller control, resulting in overcurrent, damage to power devices, and even explosions and other dangerous accidents. At this time, a circuit is needed to detect the current, identify the current size at this time, and respond to the current accordingly to protect the corresponding devices damaged by excessive current.

[0003] Nowadays, there are products that apply various overcurrent protection circuits to actual drive circuits and are welded on DBC substrates. DBC substrates are copper-clad ceramic substrates with a ceramic insulator as a base plate and a layer of metal copper on the base plate. However, the existing overcurrent protection circuits are complex, with many components and all components need to be welded, making the circuit welding difficult and the production cost high.

[0004] Therefore, there is an urgent need to develop an overcurrent protection circuit to solve one or more of the above-mentioned problems. Utility Model Content

[0005] In view of this, in order to solve the above technical problems or part of the technical problems, an embodiment of the utility model provides an overcurrent protection circuit.

[0006] In a first aspect, the present application provides an overcurrent protection circuit, the circuit comprising: a power supply subcircuit, a logic control subcircuit, a first drive subcircuit, a second drive subcircuit, an output current sampling subcircuit, and a hysteresis comparison subcircuit;

[0007] The output end of the power supply subcircuit is connected to the logic control subcircuit, the first drive subcircuit, the second drive subcircuit, the output current sampling subcircuit and the hysteresis comparison subcircuit;

[0008] The output end of the logic control subcircuit is connected to the input end of the first drive subcircuit;

[0009] The output end of the first driving sub-circuit is connected to the input end of the second driving sub-circuit;

[0010] The output end of the second driving sub-circuit is connected to the input end of the output current sampling sub-circuit;

[0011] The output end of the output current sampling subcircuit is connected to the input end of the hysteresis comparison subcircuit;

[0012] The output end of the hysteresis comparison subcircuit is connected to the input end of the logic control subcircuit.

[0013] In a possible implementation manner, the input end of the first driving sub-circuit receives the control signal output by the logic control sub-circuit, and the output end of the first driving sub-circuit outputs the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal and the third lower bridge signal to the second driving sub-circuit;

[0014] The first driving sub-circuit includes six groups of integrated sub-circuits with the same power, and any of the integrated sub-circuits is provided with a first port, a second port, a third port, a fourth port, a fifth port, a sixth port, a seventh port and an eighth port;

[0015] The first port and the fifth port are respectively connected to the positive power output terminal and the negative power output terminal of the power sub-circuit output terminal; the second port and the sixth port are grounded, and the third port is connected to the fourth port and then connected to the input terminal of the second driving sub-circuit to respectively output the first upper bridge signal, or the second upper bridge signal, or the third upper bridge signal, or the first lower bridge signal, or the second lower bridge signal, or the third lower bridge signal; the seventh port is a vacant port, and the eighth port is connected to the output terminal of the logic control sub-circuit to receive the control signal output by the logic control sub-circuit.

[0016] In a possible implementation manner, the input end of the second driving sub-circuit receives the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal and the third lower bridge signal output by the first driving sub-circuit, and the output end of the second driving sub-circuit outputs the current sampling signal to the output current sampling sub-circuit;

[0017] The second driving sub-circuit includes six groups of circuit units, namely a first circuit unit, a second circuit unit, a third circuit unit, a fourth circuit unit, a fifth circuit unit and a sixth circuit unit, which sequentially receive the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal and the third lower bridge signal output by the first driving sub-circuit.

[0018] In a possible implementation manner, any of the circuit units includes: a MOS tube and a circuit sub-unit;

[0019] The circuit subunit includes a voltage stabilizing diode, a first driving resistor, a second driving resistor, a third driving resistor and a recovery diode;

[0020] The gate of the MOS tube is respectively connected to the first driving resistor, the second driving resistor, the third driving resistor, and one end of the voltage stabilizing diode;

[0021] The other ends of the voltage stabilizing diode and the third driving resistor are connected to the source of the MOS tube, the other end of the second driving resistor is connected to the anode of the recovery diode, and the cathode of the recovery diode is connected to the other end of the first driving resistor to input the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal, or the third lower bridge signal output by the first driving sub-circuit.

[0022] In a possible implementation manner, the input end of the output current sampling subcircuit receives the current sampling signal output by the second driving subcircuit, and the output end of the output current sampling subcircuit outputs the sampled electrical signal to the hysteresis comparison subcircuit;

[0023] The output current sampling subcircuit includes a group of sampling resistors arranged in parallel.

[0024] In a possible implementation manner, the input end of the hysteresis comparison subcircuit receives the sampled electrical signal output by the output current sampling subcircuit, compares the sampled electrical signal with an overcurrent protection reference electrical signal, and outputs a corresponding level signal.

[0025] In a possible implementation manner, the level signal is a high level signal or a low level signal;

[0026] The hysteresis comparison subcircuit is provided with a first signal threshold and a second signal threshold. When the sampling electrical signal output by the output current sampling subcircuit is higher than the first signal threshold and lower than the second signal threshold, the corresponding high-level signal is output; when the sampling electrical signal output by the output current sampling subcircuit is higher than the second signal threshold, the corresponding low-level signal is output.

[0027] In a possible implementation, the hysteresis comparison subcircuit includes an operational amplifier subcircuit, the reverse end of the operational amplifier subcircuit is connected to a first comparison resistor and one end of a first comparison capacitor, the other end of the first comparison resistor is connected to the output end of the output current sampling subcircuit, and the other end of the first comparison capacitor is grounded;

[0028] The positive end of the operational amplifier sub-circuit is respectively connected to one end of the second comparison resistor, the second comparison capacitor, the third comparison resistor, and the fourth comparison resistor; the other end of the second comparison resistor is connected to the other end of the second comparison capacitor and then grounded; the other end of the third comparison resistor is connected to the output end of the operational amplifier sub-circuit and then connected to one end of the sixth comparison resistor and the fourth comparison capacitor, respectively; one end of the sixth comparison resistor is also connected to the output end of the power supply sub-circuit; the other end of the sixth comparison resistor is connected to the other end of the fourth comparison resistor and then connected to the output end of the power supply sub-circuit; the other end of the fourth comparison capacitor is connected to one end of the third comparison capacitor and then grounded; the other end of the third comparison capacitor is connected to the output end of the power supply sub-circuit.

[0029] In one possible implementation, the input end of the logic control subcircuit receives the level signal output by the hysteresis comparison subcircuit, and the output end of the logic control subcircuit outputs a corresponding control signal, the level signal is a high level signal or a low level signal, and the control signal is an on signal or an off signal.

[0030] In a possible implementation manner, when the control signal received by the first driving sub-circuit is a shutdown signal, the first driving sub-circuit instructs the second driving sub-circuit to suspend operation.

[0031] The above-mentioned technical solution provided by the embodiment of the present application has the following advantages compared with the prior art: the embodiment of the present application provides an overcurrent protection circuit, which can restart the protected object after overcurrent protection is performed without setting up a reset circuit, which not only saves printed circuit board space, but also reduces implementation costs. The hysteresis comparison circuit limits the overcurrent protection point within two thresholds, preventing the circuit from being repeatedly opened and closed due to interference from external factors such as noise, thereby improving the stability and anti-interference ability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings herein are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present utility model, and together with the description, are used to explain the principles of the present utility model.

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0034] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0035] Figure 1 A schematic diagram of the structure of an overcurrent protection circuit provided in an embodiment of the present application;

[0036] Figure 2 A schematic diagram of the structure of a first driving sub-circuit provided in an embodiment of the present application;

[0037] Figure 3 A schematic diagram of the structure of a second driving sub-circuit provided in an embodiment of the present application;

[0038] Figure 4 A schematic diagram of the structure of an output current sampling subcircuit provided in an embodiment of the present application;

[0039] Figure 5 Schematic diagram of the structure of the hysteresis comparison sub-circuit provided in the embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0041] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention may repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0042] At present, in the case of overcurrent, the common method is to shut down all power devices by outputting a control signal through a controller. To realize this function, software can be used to implement overcurrent protection. However, when the current is too large, for electronic devices, it is generally necessary to achieve a fast response within a few microseconds, and the controller sends a signal to stop the circuit operation to avoid damage during the circuit. However, this method often has a long program execution cycle, which is much higher than the response time when an overcurrent fault occurs. Therefore, when an overcurrent occurs, the power device is likely to be damaged. Another method is to implement it from hardware. This method has a faster response speed and can better avoid device damage caused by overcurrent. In general, motor drivers often use operational amplifiers, comparators, dedicated overcurrent protection ICs or use basic components such as transistors and resistors to implement overcurrent protection functions. In order to solve the problem that the prior art is repeatedly opened and closed due to interference from external factors such as noise, the present application provides an overcurrent protection circuit and designs a fast shutdown circuit at the same time. When the current is too large, the entire circuit can be shut down more quickly.

[0043] Figure 1 Schematic diagram of the structure of the overcurrent protection circuit provided in the embodiment of the present application, such as Figure 1 As shown, the circuit includes: a power supply subcircuit, a logic control subcircuit, a first drive subcircuit, a second drive subcircuit, an output current sampling subcircuit, and a hysteresis comparison subcircuit;

[0044] The output end of the power supply subcircuit is connected to the logic control subcircuit, the first drive subcircuit, the second drive subcircuit, the output current sampling subcircuit and the hysteresis comparison subcircuit;

[0045] The output end of the logic control subcircuit is connected to the input end of the first drive subcircuit;

[0046] The output end of the first driving sub-circuit is connected to the input end of the second driving sub-circuit;

[0047] The output end of the second driving sub-circuit is connected to the input end of the output current sampling sub-circuit;

[0048] The output end of the output current sampling subcircuit is connected to the input end of the hysteresis comparison subcircuit;

[0049] The output end of the hysteresis comparison subcircuit is connected to the input end of the logic control subcircuit.

[0050] In this embodiment, the overcurrent protection circuit 100 includes a logic control subcircuit 10, a hysteresis comparison subcircuit 20, a first drive subcircuit 30, a power supply subcircuit 40, a second drive subcircuit 50, and a current sampling subcircuit 60. The output current sampling subcircuit 60 is used to sample the output current of the second drive subcircuit 50 of the protected object and convert it into a corresponding sampled electrical signal. The hysteresis comparison subcircuit 20 is connected to the output current sampling subcircuit 60, and is used to receive the sampled electrical signal output by the output current sampling subcircuit 60 and output a level signal according to the magnitude relationship between the sampled electrical signal and the overcurrent protection reference electrical signal.

[0051] The overcurrent protection circuit provided in the embodiment of the present application outputs a level signal through the magnitude relationship between the sampling current signal and the overcurrent protection reference electrical signal, and when the sampling electrical signal is greater than the second reference voltage, outputs a low-level signal to the second driving subcircuit 50 of the protected object, and when the sampling electrical signal is less than the first reference input voltage, maintains a stable operating state, outputs a high-level working signal to the first driving subcircuit 30, and then drives the second driving subcircuit 50 of the protected object, thereby being able to use the same circuit to achieve overcurrent protection and overcurrent restart, thereby simplifying the design of the overcurrent protection circuit 100, and restarting the second driving subcircuit 50 of the protected object after overcurrent protection without setting up a reset circuit, which not only avoids the circuit from being repeatedly opened and closed due to interference from external factors such as noise, thereby improving the reliability of the circuit, but also reduces the implementation cost. In addition, the hysteresis comparison subcircuit 10 limits the overcurrent protection point to two thresholds, and the sampling current will not prevent the protection circuit from being repeatedly opened and closed due to a certain external factor, thereby ensuring the reliability of the protection circuit;

[0052] Figure 2 is a schematic diagram of the structure of the first driving sub-circuit provided in the embodiment of the present application, such as Figure 2 As shown, the input end of the first driving sub-circuit receives the control signal output by the logic control sub-circuit, and the output end of the first driving sub-circuit outputs the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal and the third lower bridge signal to the second driving sub-circuit;

[0053] The first driving sub-circuit includes six groups of integrated sub-circuits with the same power, and any of the integrated sub-circuits is provided with a first port, a second port, a third port, a fourth port, a fifth port, a sixth port, a seventh port and an eighth port;

[0054] The first port and the fifth port are respectively connected to the positive power output terminal and the negative power output terminal of the power sub-circuit output terminal; the second port and the sixth port are grounded, and the third port is connected to the fourth port and then connected to the input terminal of the second driving sub-circuit to respectively output the first upper bridge signal, or the second upper bridge signal, or the third upper bridge signal, or the first lower bridge signal, or the second lower bridge signal, or the third lower bridge signal; the seventh port is a vacant port, and the eighth port is connected to the output terminal of the logic control sub-circuit to receive the control signal output by the logic control sub-circuit.

[0055] In this embodiment, the first driving sub-circuit 30 is connected to the logic control sub-circuit 10, and is used to receive the output logic signal of the logic control sub-circuit 10 and determine the output signal of the first driving sub-circuit 30 according to the output logic signal;

[0056] Specifically, the input of the first driving subcircuit 30 is connected to the output of the logic control subcircuit 10. The input end of the first driving subcircuit 30 is connected to the output end of the logic control subcircuit 10. When the output of the logic control subcircuit 10 is a shutdown signal, the first driving subcircuit 30 instructs the second driving subcircuit 50 not to work. When the output of the logic control subcircuit 10 is a non-shutdown signal, the first driving subcircuit 30 works normally and drives the second driving subcircuit 50.

[0057] Furthermore, the six driving signals output by the first driving subcircuit are respectively connected to the gates of the upper bridge and lower bridge MOS tubes of the second driving circuit, H represents the upper bridge signal, and L represents the lower bridge signal; the upper bridge signal and the lower bridge signal can be either high level or low level.

[0058] The first driving sub-circuit 30 is composed of six identical power integrated sub-circuits (amplifier chips), the amplifier chip power supply VCC is connected to port 1; port 2 and port 6 are connected to the ground; port 3 and port 4 are output ports that output the first upper bridge signal, or the second upper bridge signal, or the third upper bridge signal, or the first lower bridge signal, or the second lower bridge signal, or the third lower bridge signal (corresponding to H1 signal, H2 signal, H3 signal, L1 signal, L2 signal, L3 signal in the schematic diagram); port 5 is connected to the negative power supply; port 7 is vacant; port 8 receives the control signal output by the logic control sub-circuit (corresponding to the PWM-IN signal in the schematic diagram).

[0059] Figure 3 is a schematic diagram of the structure of the second driving sub-circuit provided in the embodiment of the present application, such as Figure 3As shown, the input end of the second driving sub-circuit receives the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal and the third lower bridge signal output by the first driving sub-circuit, and the output end of the second driving sub-circuit outputs a current sampling signal to the output current sampling sub-circuit;

[0060] The second driving sub-circuit includes six groups of circuit units, namely a first circuit unit, a second circuit unit, a third circuit unit, a fourth circuit unit, a fifth circuit unit and a sixth circuit unit, which sequentially receive the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal and the third lower bridge signal output by the first driving sub-circuit.

[0061] In this embodiment, the first driving sub-circuit 30 is connected to the second driving sub-circuit 50, and is used to receive the output signal of the first driving sub-circuit 30 and determine the working state of the second driving sub-circuit 50 according to the output signal. The second driving sub-circuit 50 is a three-phase bridge driving circuit;

[0062] Specifically, the input end of the second driving subcircuit 50 is connected to the output end of the first driving subcircuit 30, and the output end of the first driving subcircuit 30 serves as the input end of the second driving unit 50. The first driving subcircuit 30 is used to instruct the second driving subcircuit 50 to work normally or pause.

[0063] Schematically, the second driving sub-circuit 50 is composed of 6 MOS tubes with the same parameters and 18 resistors to form a three-phase bridge driving circuit. The six output signals output by the first driving sub-circuit 30, the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal, and the third lower bridge signal (corresponding to H1 signal, H2 signal, H3 signal, L1 signal, L2 signal, and L3 signal in the schematic diagram) are respectively connected to the H1 port, H2 port, H3 port, L1 port, L2 port, and L3 port of the second driving sub-circuit 50 as input signals of the second driving sub-circuit 50.

[0064] In a possible implementation manner, any of the circuit units includes: a MOS tube and a circuit sub-unit;

[0065] The circuit subunit includes a voltage stabilizing diode, a first driving resistor, a second driving resistor, a third driving resistor and a recovery diode;

[0066] The gate of the MOS tube is respectively connected to the first driving resistor, the second driving resistor, the third driving resistor, and one end of the voltage stabilizing diode;

[0067] The other ends of the voltage regulator diode and the third driving resistor are connected to the source of the MOS tube, the other end of the second driving resistor is connected to the anode of the recovery diode, and the cathode of the recovery diode is connected to the other end of the first driving resistor to input the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal, or the third lower bridge signal output by the first driving sub-circuit 30.

[0068] In this embodiment, the fast recovery diodes D1, D2, D3, D4, D5, and D6 in the second driving sub-circuit 50 are respectively used to quickly release the charge between the gate and the source of the MOS tube and reduce the turn-off loss. When the gate is turned off, the voltage drop generated by the current on the resistor is greater than the turn-on voltage drop of the fast recovery diode. At this time, the fast recovery diode will be turned on. After being turned on, as the current decreases, the role of the diode in the circuit becomes smaller and smaller. The circuit can significantly reduce the turn-off delay time of the MOS tube. The second driving resistors (corresponding to R2, R5, R8, R11, R14, and R17 in the schematic diagram) are respectively used to prevent the fast recovery diode from being damaged due to excessive current when the gate is turned off. The voltage-stabilizing diodes VD1, VD2, VD3, VD4, VD5, and VD6 are used to provide electrostatic protection and suppress spike noise. The OCP port of the second driving sub-circuit 50 outputs a driving signal to the output current sampling sub-circuit; when the second driving sub-circuit 50 outputs a signal to drive the motor, the U1 port, V1 port, and W1 port of the second driving sub-circuit 50 are the output signals of the three-phase brushless motor U, V, and W, respectively.

[0069] Figure 4 Schematic diagram of the structure of the output current sampling subcircuit provided in the embodiment of the present application, such as Figure 4 As shown, the input end of the output current sampling subcircuit receives the current sampling signal output by the second driving subcircuit, and the output end of the output current sampling subcircuit outputs the sampling electrical signal to the hysteresis comparison subcircuit;

[0070] The output current sampling subcircuit includes a group of sampling resistors arranged in parallel.

[0071] Specifically, the output end of the second driving subcircuit should output an OCP signal to the output current sampling subcircuit. The output current sampling subcircuit of this example is composed of a small resistor formed by connecting ten identical resistors R13, R14, R15, R16, R17, R18, R19, R20, R21, R22, and R23 in parallel to sample the current signal output by the second driving subcircuit 50. After sampling, the output voltage acquisition signal enters the hysteresis comparison subcircuit 20 for comparison to control the opening and closing of the circuit.

[0072] Figure 5Schematic diagram of the structure of the hysteresis comparison sub-circuit 20 provided in the embodiment of the present application, as shown in Figure 5 As shown, the input end of the hysteresis comparison subcircuit 20 receives the sampled electrical signal output by the output current sampling subcircuit 60, compares the sampled electrical signal with the overcurrent protection reference electrical signal, and outputs a corresponding level signal.

[0073] In this embodiment, the input end of the hysteresis comparison sub-circuit 20 is connected to the output current sampling sub-circuit 60, and is used to receive the output voltage signal of the output current sampling sub-circuit 60 and output a comparison signal according to the magnitude relationship between the sampled voltage signal and the overcurrent protection reference voltage, and output a corresponding level signal to the logic control sub-circuit 10.

[0074] The output end of the hysteresis comparison subcircuit 20 is connected to the logic control subcircuit 10, and is used to receive the output signal of the hysteresis comparison subcircuit 20 and perform a logic operation based on the level signal output by the hysteresis comparison subcircuit 20 and the logic control subcircuit 10 to obtain an output logic signal (also called a level signal).

[0075] In a possible implementation manner, the level signal is a high level signal or a low level signal;

[0076] The hysteresis comparison subcircuit 20 is provided with a first signal threshold and a second signal threshold. When the sampling electrical signal output by the output current sampling subcircuit 60 is higher than the first signal threshold and lower than the second signal threshold, the corresponding high-level signal is output; when the sampling electrical signal output by the output current sampling subcircuit 60 is higher than the second signal threshold, the corresponding low-level signal is output.

[0077] The hysteresis comparison subcircuit 20 has two thresholds, the lower threshold is recorded as the first signal threshold U1, and the higher threshold is recorded as the second signal threshold U2. When the sampling voltage converted by the output sampling current subcircuit 60 is higher than the second signal threshold U2 of the hysteresis comparison subcircuit 20, the hysteresis comparison subcircuit 20 outputs a low-level signal. After being turned off, it is turned on when the sampling voltage output by the output sampling current subcircuit 60 is just higher than the first signal threshold U1 of the hysteresis comparison subcircuit 20. At this time, the hysteresis comparison subcircuit 20 outputs a high-level signal.

[0078] It should be noted that, in the present embodiment, the voltage value of the first signal threshold is lower than the second signal threshold, the first signal threshold may also be referred to as the first reference voltage, and the second signal threshold may also be referred to as the second reference voltage. When the sampling voltage input to the hysteresis comparison subcircuit 20 is higher than the second reference voltage, the hysteresis comparison subcircuit 20 outputs a low-level signal; when the sampling voltage input to the hysteresis comparison subcircuit 20 is higher than the first reference voltage but lower than the second reference voltage, the hysteresis comparison subcircuit 20 outputs a high-level signal.

[0079] In a possible implementation, the hysteresis comparison subcircuit includes an operational amplifier subcircuit, the reverse end of the operational amplifier subcircuit is connected to a first comparison resistor and one end of a first comparison capacitor, the other end of the first comparison resistor is connected to the output end of the output current sampling subcircuit, and the other end of the first comparison capacitor is grounded;

[0080] The positive end of the operational amplifier sub-circuit is respectively connected to one end of the second comparison resistor, the second comparison capacitor, the third comparison resistor, and the fourth comparison resistor; the other end of the second comparison resistor is connected to the other end of the second comparison capacitor and then grounded; the other end of the third comparison resistor is connected to the output end of the operational amplifier sub-circuit and then connected to one end of the sixth comparison resistor and the fourth comparison capacitor, respectively; one end of the sixth comparison resistor is also connected to the output end of the power supply sub-circuit; the other end of the sixth comparison resistor is connected to the other end of the fourth comparison resistor and then connected to the output end of the power supply sub-circuit; the other end of the fourth comparison capacitor is connected to one end of the third comparison capacitor and then grounded; the other end of the third comparison capacitor is connected to the output end of the power supply sub-circuit.

[0081] In this embodiment, the hysteresis comparison subcircuit 20 is composed of an operational amplifier subcircuit, a resistor, a capacitor, and a power supply. The sampling signal output by the output current sampling subcircuit 60 is used as the input of the hysteresis comparison subcircuit, and is connected to the input resistor first comparison resistor (R1). One end of R1 is connected to the inverting input end of the operational amplifier, and is connected to the first comparison capacitor (C1) and grounded. R1 and C1 form a low-pass filter to filter out high-frequency noise of the sampling signal.

[0082] Furthermore, the operational amplifier subcircuit is powered by a single power supply, the positive end of the operational amplifier subcircuit is connected to the power supply, the negative end is connected to the ground, the third comparison capacitor (C3) is connected to the ground, and is used to filter the noise of the power supply, one side of the power supply is directly connected to one end of the fourth comparison resistor (R4), the other end of the power supply is connected to the sixth comparison resistor (R6), R6 is connected to the fourth comparison capacitor (C4), C4 is connected to the ground, the middle of R6 and C4 is connected to the output end of the operational amplifier subcircuit, the output end of the operational amplifier subcircuit is connected to the third comparison resistor (R3), R3 is connected to the second comparison resistor (R2), R3 is connected to the non-inverting input end of the operational amplifier subcircuit, R2 is connected to the ground, R4 is connected to C2, R4 is connected to R3, and C2 is connected to the ground.

[0083] In one possible implementation, the input end of the logic control subcircuit receives the level signal output by the hysteresis comparison subcircuit, and the output end of the logic control subcircuit outputs a corresponding control signal, the level signal is a high level signal or a low level signal, and the control signal is an on signal or an off signal.

[0084] In this embodiment, a certain input terminal of the logic control sub-circuit 10 is connected to the output terminal of the hysteresis comparison sub-circuit 20 , and the output terminal of the hysteresis comparison sub-circuit 20 serves as the input terminal of the logic control sub-circuit 10 .

[0085] Furthermore, the input of the logic control subcircuit 10 is the output signal of the hysteresis comparison subcircuit 20. When the sampling current of the output sampling subcircuit 60 is too large, resulting in the output of the hysteresis comparison subcircuit 20 being a low-level signal, the logic control subcircuit 10 performs an AND operation so that the output of the logic control subcircuit 10 is a shutdown signal. When the voltage decreases and the output of the hysteresis comparison subcircuit 20 is a high-level signal, the logic control subcircuit 10 performs an AND operation so that the output of the logic control subcircuit 10 is a start signal.

[0086] In a possible implementation manner, when the control signal received by the first driving sub-circuit is a shutdown signal, the first driving sub-circuit instructs the second driving sub-circuit to suspend operation.

[0087] In addition, when the control signal received by the first driving sub-circuit is a start signal, the first driving sub-circuit instructs the second driving sub-circuit to restart operation.

[0088] In this embodiment, after the logic control subcircuit 10 outputs a shutdown signal to the first drive subcircuit 30, the first drive subcircuit 30 is controlled to output a drive signal to instruct the second drive subcircuit 50 to stop working. Overcurrent protection is implemented for the second drive subcircuit 50 as the protection object. After the output terminal of the hysteresis comparison subcircuit 20 outputs a low-level signal, the second drive subcircuit 50 does not work, and the output sampling subcircuit 60 outputs a lower sampling voltage. Under the action of the shutdown signal, the hysteresis comparison subcircuit 20 can pull down the reference input voltage of the second input terminal of the hysteresis comparison subcircuit 20, and then adjust the reference input voltage of the second input terminal of the hysteresis comparison subcircuit 20 from the second reference voltage to the first reference voltage, and the second reference voltage serves as a stable reference voltage of the overcurrent protection circuit; the first input terminal of the hysteresis comparison subcircuit 20 is zero at this time, and the reference voltage has been adjusted from the second reference voltage to the first reference voltage at this time, and the hysteresis comparison subcircuit 20 outputs a high-level signal, so the overcurrent protection circuit maintains normal operation at this time, and the entire circuit starts to work normally; there is no need to set up a reset circuit separately to restart the protected object after the overcurrent protection is performed, which not only saves the printed circuit board space, but also reduces the implementation cost, and the hysteresis comparison subcircuit 20 limits the overcurrent protection point to two thresholds (corresponding to the sampling voltage between the first reference voltage and the second reference voltage), preventing the circuit from being repeatedly opened and closed due to interference from external factors such as noise, thereby improving the stability and anti-interference ability of the system.

[0089] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a general hardware platform, and of course, by hardware. Based on this understanding, the above technical solution, in essence, or the part that contributes to the relevant technology, can be embodied in the form of a software product, which can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiment.

[0090] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0091] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. An overcurrent protection circuit, characterized in that: include: A power supply sub-circuit, a logic control sub-circuit, a first drive sub-circuit, a second drive sub-circuit, an output current sampling sub-circuit, and a hysteresis comparison sub-circuit; The output end of the power supply subcircuit is connected to the logic control subcircuit, the first drive subcircuit, the second drive subcircuit, the output current sampling subcircuit and the hysteresis comparison subcircuit; The output end of the logic control subcircuit is connected to the input end of the first drive subcircuit; The output end of the first driving sub-circuit is connected to the input end of the second driving sub-circuit; The output end of the second driving sub-circuit is connected to the input end of the output current sampling sub-circuit; The output end of the output current sampling subcircuit is connected to the input end of the hysteresis comparison subcircuit; The output end of the hysteresis comparison subcircuit is connected to the input end of the logic control subcircuit.

2. The overcurrent protection circuit according to claim 1, characterized in that: The input end of the first driving sub-circuit receives the control signal output by the logic control sub-circuit, and the output end of the first driving sub-circuit outputs the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal and the third lower bridge signal to the second driving sub-circuit; The first driving sub-circuit includes six groups of integrated sub-circuits with the same power, and any of the integrated sub-circuits is provided with a first port, a second port, a third port, a fourth port, a fifth port, a sixth port, a seventh port and an eighth port; The first port and the fifth port are respectively connected to the positive power output terminal and the negative power output terminal of the power sub-circuit output terminal; the second port and the sixth port are grounded, and the third port is connected to the fourth port and then connected to the input terminal of the second driving sub-circuit to respectively output the first upper bridge signal, or the second upper bridge signal, or the third upper bridge signal, or the first lower bridge signal, or the second lower bridge signal, or the third lower bridge signal; the seventh port is a vacant port, and the eighth port is connected to the output terminal of the logic control sub-circuit to receive the control signal output by the logic control sub-circuit.

3. The overcurrent protection circuit according to claim 1, characterized in that: The input end of the second driving sub-circuit receives the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal and the third lower bridge signal output by the first driving sub-circuit, and the output end of the second driving sub-circuit outputs a current sampling signal to the output current sampling sub-circuit; The second driving sub-circuit includes six groups of circuit units, namely a first circuit unit, a second circuit unit, a third circuit unit, a fourth circuit unit, a fifth circuit unit and a sixth circuit unit, which sequentially receive the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal and the third lower bridge signal output by the first driving sub-circuit.

4. The overcurrent protection circuit according to claim 3, characterized in that: Any of the circuit units comprises: a MOS tube and a circuit sub-unit; The circuit subunit includes a voltage stabilizing diode, a first driving resistor, a second driving resistor, a third driving resistor and a recovery diode; The gate of the MOS tube is respectively connected to the first driving resistor, the second driving resistor, the third driving resistor, and one end of the voltage stabilizing diode; The other ends of the voltage stabilizing diode and the third driving resistor are connected to the source of the MOS tube, the other end of the second driving resistor is connected to the anode of the recovery diode, and the cathode of the recovery diode is connected to the other end of the first driving resistor to input the first upper bridge signal, the second upper bridge signal, the third upper bridge signal, the first lower bridge signal, the second lower bridge signal, or the third lower bridge signal output by the first driving sub-circuit.

5. The overcurrent protection circuit according to claim 1, characterized in that: The input end of the output current sampling subcircuit receives the current sampling signal output by the second driving subcircuit, and the output end of the output current sampling subcircuit outputs the sampled electrical signal to the hysteresis comparison subcircuit; The output current sampling subcircuit includes a group of sampling resistors arranged in parallel.

6. The overcurrent protection circuit according to claim 1, characterized in that: The input end of the hysteresis comparison subcircuit receives the sampled electrical signal output by the output current sampling subcircuit, compares the sampled electrical signal with the overcurrent protection reference electrical signal, and outputs a corresponding level signal to the logic control subcircuit.

7. The overcurrent protection circuit according to claim 6, characterized in that: The level signal is a high level signal or a low level signal; The hysteresis comparison subcircuit is provided with a first signal threshold and a second signal threshold. When the sampling electrical signal output by the output current sampling subcircuit is higher than the first signal threshold and lower than the second signal threshold, the corresponding high-level signal is output; when the sampling electrical signal output by the output current sampling subcircuit is higher than the second signal threshold, the corresponding low-level signal is output.

8. The overcurrent protection circuit according to claim 7, characterized in that: The hysteresis comparison subcircuit includes an operational amplifier subcircuit, the reverse end of the operational amplifier subcircuit is connected to a first comparison resistor and one end of a first comparison capacitor, the other end of the first comparison resistor is connected to the output end of the output current sampling subcircuit, and the other end of the first comparison capacitor is grounded; The positive end of the operational amplifier sub-circuit is respectively connected to one end of the second comparison resistor, the second comparison capacitor, the third comparison resistor, and the fourth comparison resistor; the other end of the second comparison resistor is connected to the other end of the second comparison capacitor and then grounded; the other end of the third comparison resistor is connected to the output end of the operational amplifier sub-circuit and then connected to one end of the sixth comparison resistor and the fourth comparison capacitor, respectively; one end of the sixth comparison resistor is also connected to the output end of the power supply sub-circuit; the other end of the sixth comparison resistor is connected to the other end of the fourth comparison resistor and then connected to the output end of the power supply sub-circuit; the other end of the fourth comparison capacitor is connected to one end of the third comparison capacitor and then grounded; the other end of the third comparison capacitor is connected to the output end of the power supply sub-circuit.

9. The overcurrent protection circuit according to claim 8, characterized in that: The input end of the logic control subcircuit receives the level signal output by the hysteresis comparison subcircuit, and the output end of the logic control subcircuit outputs a corresponding control signal, wherein the level signal is a high level signal or a low level signal, and the control signal is an on signal or an off signal.

10. The overcurrent protection circuit according to claim 3, characterized in that: In a case where the control signal received by the first driving sub-circuit is a shutdown signal, the first driving sub-circuit instructs the second driving sub-circuit to suspend operation.

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