Full-bridge power-on short circuit detection protection circuit

Abstract

The utility model discloses a full-bridge power-on short circuit detection protection circuit, which relates to the technical field of short circuit detection, and is characterized in that the full-bridge power-on short circuit detection protection circuit comprises a full-bridge circuit, a control unit, a bus switch unit and a short circuit diagnosis unit, the bus switch unit comprises a first interface, a second interface, a third interface and a fourth interface, the first interface is electrically connected with the positive electrode of a power supply, the second interface is electrically connected with one end of the full-bridge circuit, the other end of the full-bridge circuit is electrically connected with the negative electrode of the power supply, the third interface is electrically connected with the control unit, and the fourth interface is electrically connected with the short circuit diagnosis unit and the control unit. The short-circuit diagnosis unit is electrically connected between a high-side switch and a low-side switch of the full-bridge circuit, the short-circuit diagnosis unit is electrically connected with the control unit, and the control unit is electrically connected with the full-bridge circuit. The full-bridge power-on short circuit detection protection circuit has the advantage of being capable of protecting the circuit and electronic components.

Description

TECHNICAL FIELD

[0001] The utility model relates to short circuit detection technical field more specifically, it relates to a kind of full-bridge power-on short circuit detection protection circuit. BACKGROUND

[0002] Full-bridge output circuit, i.e. four power switching devices are connected in the form of a graph, electrical architecture of load across the middle point of two bridge arms, is widely used in PWM load control.If any switching device in four power switching devices exists short circuit, after starting output, i.e. short circuit phenomenon of power supply and ground occurs, causes instantaneous large current to appear, can lead to power switching device, power supply damage, even cause fire.Therefore, short circuit detection needs to be carried out to full-bridge output circuit before power-on.

[0003] Therefore, a new scheme needs to be proposed to solve this problem. INVENTION CONTENTS

[0004] In view of the deficiencies in the prior art, the purpose of the utility model is to solve the problem that the existing full-bridge output circuit is easy to damage circuit and electronic components when short circuit occurs.

[0005] The above technical purpose of the utility model is realized by the following technical scheme: the embodiment of the application provides a full-bridge power-on short circuit detection protection circuit, which comprises a full-bridge circuit and a control unit, and further comprises a bus switch unit and a short circuit diagnosis unit, the bus switch unit comprises a first interface, a second interface, a third interface and a fourth interface, the first interface is electrically connected to the positive electrode of a power supply, one end of the full-bridge circuit is electrically connected to the second interface, the other end of the full-bridge circuit is electrically connected to the negative electrode of the power supply, the third interface is electrically connected to the control unit, the fourth interface is respectively electrically connected to the short circuit diagnosis unit and the control unit, the short circuit diagnosis unit is electrically connected to the full-bridge circuit and is used for diagnosing short circuit of the full-bridge circuit, the short circuit diagnosis unit is electrically connected to the control unit so that the output signal of the short circuit diagnosis unit can be transmitted to the control unit, and the control unit is electrically connected to the full-bridge circuit and transmits a control signal to the full-bridge circuit.

[0006] In one embodiment, the full-bridge circuit comprises a first terminal, a second terminal and a third terminal, further comprises a first voltage dividing circuit, the first voltage dividing circuit comprises a first resistor R1 and a second resistor R2, one end of the first resistor R1 and one end of the second resistor R2 are electrically connected to the first terminal and the third terminal respectively, the other end of the first resistor R1 and the other end of the second resistor R2 are electrically connected and electrically connected to the second terminal, and one end of the second resistor R2 close to the short circuit diagnosis unit is connected in parallel with a voltage stabilizing capacitor Cin.

[0007] In one of the embodiments, the short circuit diagnosis unit comprises a first comparator and a second comparator, a positive input end of the first comparator is electrically connected with a second voltage dividing circuit, the second voltage dividing circuit comprises a third resistor and a fourth resistor which are electrically connected, the third resistor and the fourth resistor are electrically connected with two ends of the full-bridge circuit respectively, a negative input end of the second comparator is electrically connected with a third voltage dividing circuit, the third voltage dividing circuit comprises a fifth resistor and a sixth resistor which are electrically connected, the fifth resistor and the sixth resistor are electrically connected with two ends of the full-bridge circuit respectively, the negative input end of the first comparator and the positive input end of the second comparator are electrically connected with a fourth voltage dividing circuit, the fourth voltage dividing circuit comprises a seventh resistor and an eighth resistor which are electrically connected, the seventh resistor and the eighth resistor are electrically connected with two ends of the voltage stabilizing capacitor respectively, an output end of the first comparator and an output end of the second comparator are electrically connected through a diode and gate circuit.

[0008] In one of the embodiments, the diode and gate circuit comprises a first diode and a second diode, negative poles of the first diode and the second diode are electrically connected with the first comparator and the second comparator respectively, positive poles of the first diode and the second diode are connected and electrically connected with a ninth resistor and an output signal end respectively, the ninth resistor is electrically connected with an internal power supply, the output signal end is electrically connected with the control unit and the bus switch unit respectively.

[0009] In one of the embodiments, resistance values of the seventh resistor and the eighth resistor are all greater than ten times of a resistance value of the second resistor.

[0010] In conclusion, the utility model has the following beneficial effects: the utility model discloses a short circuit detection unit is connected on the full-bridge circuit, and the output end of the short circuit detection unit is connected with the control unit and the bus switch unit, so that not only the short circuit of the full-bridge circuit can be detected, but also the power supply of the full-bridge circuit can be cut off when the short circuit of the full-bridge circuit is detected, so that the circuit and electronic components are protected, the short circuit detection unit is set to comprise a first comparator and a second comparator, and a diode and gate circuit is connected at the output end of the first comparator and the second comparator, so that when any one of the four power components of the full-bridge circuit is short-circuited, the output signal of the short circuit detection unit is low, so that the short circuit detection is convenient and accurate. BRIEF DESCRIPTION OF DRAWINGS

[0011] Fig. 1 The circuit structure schematic diagram of the full-bridge power-on short circuit detection protection circuit of the embodiment of the application;

[0012] Fig. 2 The circuit structure schematic diagram of the short circuit diagnosis unit in the full-bridge power-on short circuit detection protection circuit of the embodiment of the application;

[0013] Fig. 3 This is a schematic diagram of the circuit structure of a full-bridge circuit;

[0014] Fig. 4 This is a schematic diagram of the circuit structure of the bus switch unit in the full-bridge power-on short-circuit detection and protection circuit of an embodiment of this application.

[0015] In the diagram: 1. Full-bridge circuit; 11. First terminal; 12. Second terminal; 13. Third terminal; 2. Control unit; 3. Busbar switch unit; 31. Third diode; 32. Fourth diode; 33. First interface; 34. Second interface; 35. Third interface; 36. Fourth interface; 4. Short-circuit diagnostic unit. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] like Figs. 1 to 4 As shown, an embodiment of this application provides a full-bridge power-on short-circuit detection and protection circuit, including a full-bridge circuit 1 and a control unit 2, and further including a bus switch unit 3 and a short-circuit diagnostic unit 4. The bus switch unit 3 includes a first interface 33, a second interface 34, a third interface 35, and a fourth interface 36. The first interface 33 is electrically connected to the positive terminal of the power supply. The second interface 34 is electrically connected to one end of the full-bridge circuit 1, and the other end of the full-bridge circuit 1 is electrically connected to the negative terminal of the power supply. The third interface 35 is electrically connected to the control unit 2. The fourth interface 36 is electrically connected to both the short-circuit diagnostic unit 4 and the control unit 2. The short-circuit diagnostic unit 4 is electrically connected to the full-bridge circuit 1 and is used to perform short-circuit diagnosis on the full-bridge circuit 1. The short-circuit diagnostic unit 4 is electrically connected to the control unit 2 so that the output signal of the short-circuit diagnostic unit 4 can be transmitted to the control unit 2. The control unit 2 is electrically connected to the full-bridge circuit 1 and transmits control signals to the full-bridge circuit 1.

[0018] Specifically, the full-bridge circuit 1 is prior art, the control unit 2 can be a pwm unit in the prior art, the bus switch unit 3 can be realized by using relays, MOSFETs, chips and the like, and can be realized by using a relay switch and an AND gate circuit electrically connected, the AND gate circuit includes a third diode 31 and a fourth diode 32, the positive poles of the third diode 31 and the fourth diode 32 are electrically connected with the relay switch, the negative pole of the fourth diode 32 is electrically connected with a tenth resistor, a first interface 33 is an input end of the relay switch, a second interface 34 is an output end of the relay switch, a third interface 35 is a negative pole of the third diode 31, and a fourth interface 36 is one end of the tenth resistor.

[0019] In operation, the short-circuit diagnosis unit 4 detects the full-bridge circuit 1 and transmits a detection signal to the bus switch unit 3 and the control unit 2, when the full-bridge circuit 1 is short-circuited, the control unit 2 receives the signal and generates a signal transmitted to the bus switch unit 3, the bus switch unit 3 receives the short-circuit signal and cuts off the power supply of the full-bridge circuit 1.

[0020] The above structure is provided by connecting the short-circuit detection unit on the full-bridge circuit 1, and connecting the output ends of the short-circuit detection unit with the control unit 2 and the bus switch unit 3 respectively and transmitting the detection signal, so that not only the short-circuit condition of the full-bridge circuit 1 can be detected, but also when the full-bridge circuit 1 is detected to be short-circuited, the power supply of the full-bridge circuit 1 can be cut off, thereby protecting the circuit and electronic components.

[0021] In the embodiment, the full-bridge circuit 1 includes a first wiring end 11, a second wiring end 12 and a third wiring end 13, and further includes a first voltage dividing circuit, the first voltage dividing circuit includes a first resistor R1 and a second resistor R2, one end of the first resistor R1 and one end of the second resistor R2 are electrically connected with the first wiring end 11 and the third wiring end 13 respectively, the other end of the first resistor R1 and the other end of the second resistor R2 are electrically connected and connected with the second wiring end 12, and one end of the second resistor R2 close to the short-circuit diagnosis unit 4 is connected in parallel with a voltage stabilizing capacitor Cin.

[0022] The above structure is provided by connecting the short-circuit detection unit on the full-bridge circuit 1, and connecting the output ends of the short-circuit detection unit with the control unit 2 and the bus switch unit 3 respectively and transmitting the detection signal, so that not only the short-circuit condition of the full-bridge circuit 1 can be detected, but also when the full-bridge circuit 1 is detected to be short-circuited, the power supply of the full-bridge circuit 1 can be cut off, thereby protecting the circuit and electronic components.

[0023] In the embodiment, the short circuit diagnosis unit 4 comprises a first comparator U1 and a second comparator U2, the positive input end of the first comparator U1 is electrically connected with a second voltage dividing circuit, the second voltage dividing circuit comprises a third resistor R3 and a fourth resistor R4 which are electrically connected, the third resistor R3 and the fourth resistor R4 are respectively electrically connected with two ends of the full-bridge circuit 1, the negative input end of the second comparator U2 is electrically connected with a third voltage dividing circuit, the third voltage dividing circuit comprises a fifth resistor R5 and a sixth resistor R6 which are electrically connected, the fifth resistor R5 and the sixth resistor R6 are respectively electrically connected with two ends of the full-bridge circuit 1, the negative input end of the first comparator U1 and the positive input end of the second comparator U2 are electrically connected with a fourth voltage dividing circuit, the fourth voltage dividing circuit comprises a seventh resistor R7 and an eighth resistor R8 which are electrically connected, the seventh resistor R7 and the eighth resistor R8 are respectively electrically connected with two ends of the voltage stabilizing capacitor Cin, the output end of the first comparator U1 and the output end of the second comparator U2 are electrically connected through a diode and gate circuit.

[0024] Specifically, the full-bridge circuit 1 comprises Q1, Q2, Q3 and Q4 four field effect tubes, define the bus switch output voltage as VBR, the input voltage of the short circuit diagnosis unit 4 as Vin, the first comparator U1 is the short circuit diagnosis element of the lower bridge arm power element, when Q2 or Q4 is short-circuited, the load voltage is short-circuited to the ground, so that Vin is close to the negative pole of the power supply, the voltage at the positive input end of the first comparator U1 is the voltage after voltage division of VBR through the second voltage dividing circuit, the voltage at the negative input end of the first comparator U1 is close to 0, the resistance values of the third resistor R3 and the fourth resistor R4 are adjusted so that the output voltage of the first comparator U1 is low, the second comparator U2 is the short circuit diagnosis element of the upper bridge arm power element, when Q1 or Q3 is short-circuited, the load voltage is short-circuited to the power supply, so that Vin is close to VBR, the voltage at the positive input end of the second comparator U2 is the voltage after voltage division of Vin through the fourth voltage dividing circuit, the voltage at the negative input end of the second comparator U2 is the voltage after voltage division of VBR through the third voltage dividing circuit, the resistance values of the fifth resistor R5 and the sixth resistor R6 are adjusted so that the output voltage of the second comparator U2 is low.

[0025] In the embodiment, the diode and gate circuit comprises a first diode D1 and a second diode D2, the negative poles of the first diode D1 and the second diode D2 are respectively electrically connected with the first comparator U1 and the second comparator U2, the positive poles of the first diode D1 and the second diode D2 are connected and respectively electrically connected with a ninth resistor R9 and an output signal end, the ninth resistor R9 is electrically connected with an internal power supply, and the output signal end is respectively electrically connected with the control unit 2 and the bus switch unit 3.

[0026] The structure is arranged, the diode and the gate circuit are connected at the output end of the first comparator U1 and the second comparator U2, so that the output signal of the short-circuit diagnosis unit 4 is low when any one of the four power components of the full-bridge circuit 1 is short-circuited, so that the short-circuit detection is convenient and accurate, the output signal SIGNAL1-diagnosis output signal is output to the control unit 2, the control unit 2 diagnoses that the full-bridge circuit 1 has short-circuit, and the control signal output is cut off, and the control unit 2 transmits SIGNAL2-bus switch enable signal to the bus switch unit 3, meanwhile, the output signal end outputs SIGNAL3-bus switch reset signal to the bus switch unit 3, SIGNAL3 and SIGNAL2 constitute two outputs of the AND gate, the bus switch unit 3 is controlled to control the on-off of the full-bridge circuit 1, and the bus switch unit 3 transmits the power-on reset signal SIGNAL4 to the control unit.

[0027] In the embodiment, the resistance values of the seventh resistor R7 and the eighth resistor R8 are both greater than ten times of the resistance value of the second resistor R2.

[0028] The structure is arranged, the diode and the gate circuit are connected at the output end of the first comparator U1 and the second comparator U2, so that the output signal of the short-circuit diagnosis unit 4 is low when any one of the four power components of the full-bridge circuit 1 is short-circuited, so that the short-circuit detection is convenient and accurate, the output signal SIGNAL1-diagnosis output signal is output to the control unit 2, the control unit 2 diagnoses that the full-bridge circuit 1 has short-circuit, and the control signal output is cut off, and the control unit 2 transmits SIGNAL2-bus switch enable signal to the bus switch unit 3, meanwhile, the output signal end outputs SIGNAL3-bus switch reset signal to the bus switch unit 3, SIGNAL3 and SIGNAL2 constitute two outputs of the AND gate, the bus switch unit 3 is controlled to control the on-off of the full-bridge circuit 1, and the bus switch unit 3 transmits the power-on reset signal SIGNAL4 to the control unit.

[0029] The above only is the preferred implementation manner of the utility model, the protection scope of the utility model is not only limited to the above-mentioned embodiment, and belongs to the protection scope of the utility model for the technical scheme under the idea of the utility model. It should be pointed out that, for ordinary skilled person in the art, a number of improvements and refinements without departing from the principle of the utility model, these improvements and refinements should also be regarded as the protection scope of the utility model.

Claims

1. A full-bridge power-up short-circuit detection protection circuit comprising a full-bridge circuit (1) and a control unit (2), characterized in that: The bus switch unit (3) includes a first interface (33), a second interface (34), a third interface (35) and a fourth interface (36), the first interface (33) is electrically connected with the positive pole of the power supply, the second interface (34) is electrically connected with one end of the full-bridge circuit (1), the other end of the full-bridge circuit (1) is electrically connected with the negative pole of the power supply, the third interface (35) is electrically connected with the control unit (2), and the fourth interface (36) is electrically connected with the short-circuit diagnosis unit (4) and the control unit (2) respectively, the short-circuit diagnosis unit (4) is electrically connected with the full-bridge circuit (1) and is used for performing short-circuit diagnosis on the full-bridge circuit (1), the short-circuit diagnosis unit (4) is electrically connected with the control unit (2) so that the output signal of the short-circuit diagnosis unit (4) can be transmitted to the control unit (2), and the control unit (2) is electrically connected with the full-bridge circuit (1) and transmits a control signal to the full-bridge circuit (1).

2. The full bridge power-on short detection protection circuit of claim 1, wherein: The full-bridge circuit (1) includes a first terminal (11), a second terminal (12) and a third terminal (13), further includes a first voltage dividing circuit, the first voltage dividing circuit includes a first resistor R1 and a second resistor R2, one end of the first resistor R1 and one end of the second resistor R2 are electrically connected with the first terminal (11) and the third terminal (13) respectively, the other end of the first resistor R1 and the other end of the second resistor R2 are electrically connected and connected with the second terminal (12), and one end of the second resistor R2 is connected with a voltage stabilizing capacitor Cin in parallel.

3. The full bridge power-on short detection protection circuit of claim 2, wherein: The short-circuit diagnosis unit (4) includes a first comparator U1 and a second comparator U2, the positive input end of the first comparator U1 is electrically connected with a second voltage dividing circuit, the second voltage dividing circuit includes a third resistor R3 and a fourth resistor R4 connected in an electric manner, the third resistor R3 and the fourth resistor R4 are electrically connected with two ends of the full-bridge circuit (1) respectively, the negative input end of the second comparator U2 is electrically connected with a third voltage dividing circuit, the third voltage dividing circuit includes a fifth resistor R5 and a sixth resistor R6 connected in an electric manner, the fifth resistor R5 and the sixth resistor R6 are electrically connected with two ends of the full-bridge circuit (1) respectively, the negative input end of the first comparator U1 and the positive input end of the second comparator U2 are electrically connected with a fourth voltage dividing circuit, the fourth voltage dividing circuit includes a seventh resistor R7 and an eighth resistor R8 connected in an electric manner, the seventh resistor R7 and the eighth resistor R8 are electrically connected with two ends of the voltage stabilizing capacitor Cin respectively, and the output end of the first comparator U1 and the output end of the second comparator U2 are electrically connected through a diode and gate circuit.

4. The full bridge power-on short detection protection circuit of claim 3, wherein: The diode and gate circuit comprises a first diode D1 and a second diode D2, the negative poles of the first diode D1 and the second diode D2 are electrically connected with the first comparator U1 and the second comparator U2 respectively, the positive poles of the first diode D1 and the second diode D2 are connected and electrically connected with a ninth resistor R9 and an output signal end respectively, the ninth resistor R9 is electrically connected with an internal power supply, and the output signal end is electrically connected with the control unit (2) and the bus switch unit (3) respectively.

5. The full bridge power-on short detection protection circuit of claim 3, wherein: The resistance values of the seventh resistor R7 and the eighth resistor R8 are greater than ten times of the resistance value of the second resistor R2.

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