OBC surge voltage protection circuit

Abstract

The utility model relates to the technical field of charging systems, and belongs to an OBC surge voltage protection circuit, which is characterized by comprising a power grid voltage sampling and diagnosing circuit and a switch control circuit connected with the power grid voltage sampling and diagnosing circuit and used for controlling on-off of an input power grid, and the front section of the power grid voltage sampling and diagnosing circuit is connected with a power grid live wire L and a zero wire N; the rear end of the switch control circuit is connected with a rectifier bridge BD1, the rectifier bridge BD1 is connected to an output ground PGND, and the power grid voltage sampling and diagnosis circuit comprises a sampling circuit module used for sampling power grid voltage, a diagnosis circuit module used for diagnosing the power grid voltage and a latch circuit module used for outputting surge voltage protection signals. An RC filtering circuit module is arranged between the voltage diagnosis circuit module and the latch circuit module, and the surge voltage protection signal is connected to the switch control circuit. According to the utility model, the timely diagnosis of the surge voltage can be realized through the network voltage sampling and diagnosis line, and the switch control line is used for quickly disconnecting the power grid, so that the damage of internal devices of the OBC is effectively avoided, the protection of the surge voltage is realized, the stability of the OBC circuit is improved, and the service life of the OBC circuit is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of charging systems and belongs to an OBC surge voltage protection circuit. Background Art

[0002] OBC (On-Board Charger) is one of the key components of electric vehicles (EVs). It is responsible for converting the AC power provided by the external power grid into DC power that meets the requirements of the battery management system (BMS) so as to safely and efficiently charge the power battery pack of the electric vehicle. Since OBC is directly connected to the power grid, it may face the threat of grid voltage fluctuations and transient overvoltages (such as lightning surges, transient voltages caused by switching operations, etc.). These abnormal voltages may cause damage to the electronic components inside the OBC, affecting its normal operation or shortening its service life.

[0003] Therefore, in order to protect the OBC from being damaged when the grid voltage fluctuates greatly, how to design an OBC surge voltage protection circuit is a technical problem that needs to be solved urgently in the industry. Utility Model Content

[0004] The utility model provides an OBC surge voltage protection circuit, which can effectively solve the problems in the background technology.

[0005] In order to achieve the above object, the utility model provides the following implementation scheme:

[0006] The present application provides an OBC surge voltage protection circuit, characterized in that it includes a grid voltage sampling and diagnostic circuit and a switch control circuit connected thereto for controlling the on / off of an input grid, wherein the front section of the grid voltage sampling and diagnostic circuit is connected to a grid live wire L and a neutral wire N, and the rear section of the switch control circuit is connected to a rectifier bridge BD1, and the rectifier bridge BD1 is connected to an output ground PGND, and the grid voltage sampling and diagnostic circuit includes: a sampling circuit module for sampling a grid voltage, a diagnostic circuit module for diagnosing a grid voltage, and a latch circuit module for outputting a surge voltage protection signal, an RC filter circuit module is arranged between the voltage diagnostic circuit module and the latch circuit module, and the surge voltage protection signal is connected to the switch control circuit.

[0007] Furthermore, the sampling circuit module includes rectifier diodes D2, D3, voltage-dividing resistors R7, R9, R12, R19 and a filter capacitor C3. The positive poles of the diodes D2 and D3 are respectively connected to the live wire L and the neutral wire N of the power grid, and the negative poles are connected to one end of the resistor R7. The resistors R7, R9, R12, and R19 are connected in series in sequence. The other end of the resistor R19 is connected to the output ground PGND and is grounded. The filter capacitor C3 is connected in parallel to both ends of the resistor R19.

[0008] Furthermore, the diagnostic circuit module includes resistors R14, R16, R18, R21, a capacitor C5 and a comparator U1A, one end of the resistor R16 is connected between resistors R19 and R12, the other end of the resistor R16 is connected to the positive input end of the comparator U1A, the negative input end of the comparator U1A is connected to a resistor R18, the other end of the resistor R18 is connected to the power supply port VCC, one end of a filter capacitor C5 and one end of a resistor R21 are connected between the resistor R18 and the comparator U1A in sequence, the other end of the filter capacitor C5 and the other end of the resistor R21 are both connected to the output ground PGND, one end of the resistor R14 is connected to the power supply port VCC, and the other end of the resistor R14 is connected to the output end of the comparator U1A.

[0009] Furthermore, the RC filter circuit module includes a resistor R17 and a capacitor C4, wherein the resistor R17 is connected to the output end of the comparator U1A, and one end of the capacitor C4 is connected to the resistor R17, and the other end is connected to the output ground PGND.

[0010] Further, the latch circuit module includes a PNP transistor Q3, an NPN transistor Q4 and resistors R11, R13, R15, and R20. A capacitor C2 is connected between the base and emitter of the PNP transistor Q3, the emitter of the PNP transistor Q3 is connected to the power supply port VCC, the collector of the PNP transistor Q3 is connected to one end of the resistor R13, the other end of the resistor R13 is connected to one end of the resistor R20, and the other end of the resistor R20 is connected to the output ground PGND. The collector of the NPN transistor Q4 is connected to the base of the PNP transistor Q3 through the resistor R15, a resistor R11 is connected between the resistor R15 and the power supply port VCC, both ends of the resistor R11 are connected in parallel with the capacitor C2, the base of the NPN transistor Q4 is connected to the resistor R17, and the emitter is connected to the output ground PGND, and the collector of the PNP transistor Q3 outputs a surge voltage protection signal.

[0011] Furthermore, the switch control circuit includes diodes D5, D1, resistors R4, R6, R8, R10, NPN transistor Q2, NPN transistor Q1 and normally open relay K1, the positive electrode of the diode D5 is connected to the surge voltage protection signal, the negative electrode of the diode D5 is connected to the base of the NPN transistor Q2 through the resistor R8, the emitter of the NPN transistor Q2 is connected to the output ground PGND, the base and emitter of the NPN transistor Q2 are connected in parallel with resistor R10, the collector of the NPN transistor Q2 is connected to the base of the NPN transistor Q1, the collector of the NPN transistor Q1 is connected to the power supply port VCC, the emitter of the NPN transistor Q1 is connected to the coil of the normally open relay K1 through the resistor R4, and the base and collector of the NPN transistor Q1 are connected in parallel with resistor R6.

[0012] Furthermore, the normally open relay K1 includes antenna 1, antenna 2, antenna 3 and antenna 4, the antenna 1 and antenna 2 are connected to the live wire L of the power grid, the antenna 3 is connected to the resistor R4, and the antenna 4 is connected to the output ground PGND.

[0013] Furthermore, the rectifier bridge BD1 includes a contact 1, a contact 2, a contact 3 and a contact 4, wherein the contact 1 and the contact 4 are connected to both ends of the capacitor C1, the contact 2 is connected to the antenna 2, and the contact 3 is connected to the neutral line N of the power grid.

[0014] Compared with the prior art, the utility model provides an OBC surge voltage protection circuit, which has the following beneficial effects:

[0015] The grid voltage sampling and diagnosis circuit can realize timely diagnosis of surge voltage, and the switch control circuit can quickly disconnect the grid, thus effectively avoiding damage to the internal components of the OBC, realizing surge voltage protection, improving the stability of the OBC circuit, and extending the practical life.

[0016] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the OBC surge voltage protection circuit diagram of the utility model;

[0018] Figure 2 This is the utility model grid voltage sampling and diagnosis circuit diagram;

[0019] Figure 3 It is a switch control circuit for turning on and off the power grid of the utility model. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the scope of the utility model. In addition, in the following description, the description of the known structure and technology is omitted to avoid unnecessary confusion of the concept of the utility model.

[0021] See also Figure 1, an OBC surge voltage protection circuit, including a grid voltage sampling and diagnosis circuit and a switch control circuit connected thereto for controlling the on / off of an input grid, wherein the front section of the grid voltage sampling and diagnosis circuit is connected to a grid live wire L and a neutral wire N, the rear section of the switch control circuit is connected to a rectifier bridge BD1, and the rectifier bridge BD1 is connected to an output ground PGND, the grid voltage sampling and diagnosis circuit includes: a sampling circuit module for sampling a grid voltage, a diagnosis circuit module for diagnosing a grid voltage, and a latch circuit module for outputting a surge voltage protection signal AC_OVP, an RC filter circuit module is arranged between the voltage diagnosis circuit module and the latch circuit module, and the surge voltage protection signal AC_OVP is connected to the switch control circuit.

[0022] Specifically, see Figure 2 ,The sampling circuit module includes rectifier diodes D2, D3, voltage divider resistors R7, R9, R12, R19 and filter capacitor C3.

[0023] Among them, the positive electrodes of the diodes D2 and D3 are respectively connected to the live wire L and the neutral wire N of the power grid, and the negative electrodes are connected to one end of the resistor R7. The resistors R7, R9, R12, and R19 are connected in series in sequence. The other end of the resistor R19 is connected to the output ground PGND and is grounded. The filter capacitor C3 is connected in parallel to both ends of the resistor R19.

[0024] Among them, the diagnostic circuit module includes resistors R14, R16, R18, R21, capacitor C5 and comparator U1A, one end of the resistor R16 is connected between resistors R19 and R12, the other end of the resistor R16 is connected to the positive input end of the comparator U1A, the negative input end of the comparator U1A is connected to resistor R18, the other end of the resistor R18 is connected to the power supply port VCC, one end of the filter capacitor C5 and one end of the resistor R21 are connected between the resistor R18 and the comparator U1A in sequence, the other end of the filter capacitor C5 and the other end of the resistor R21 are both connected to the output ground PGND, one end of the resistor R14 is connected to the power supply port VCC, and the other end of the resistor R14 is connected to the output end of the comparator U1A.

[0025] Specifically, see Figure 2 The RC filter circuit module includes a resistor R17 and a capacitor C4. The resistor R17 is connected to the output end of the comparator U1A. One end of the capacitor C4 is connected to the resistor R17, and the other end is connected to the output ground PGND.

[0026] Specifically, see Figure 2The latch circuit module includes a PNP transistor Q3, an NPN transistor Q4 and resistors R11, R13, R15 and R20. A capacitor C2 is connected between the base and emitter of the PNP transistor Q3. The emitter of the PNP transistor Q3 is connected to the power supply port VCC. The collector of the PNP transistor Q3 is connected to one end of the resistor R13. The other end of the resistor R13 is connected to one end of the resistor R20. The other end of the resistor R20 is connected to the output ground PGND. The collector of the NPN transistor Q4 is connected to the base of the PNP transistor Q3 through the resistor R15. A resistor R11 is connected between the resistor R15 and the power supply port VCC. Both ends of the resistor R11 are connected in parallel with the capacitor C2. The base of the NPN transistor Q4 is connected to the resistor R17, and the emitter is connected to the output ground PGND. The collector of the PNP transistor Q3 outputs a surge voltage protection signal AC_OVP.

[0027] Specifically, see Figure 3 The switch control circuit includes diodes D5, D1, resistors R4, R6, R8, R10, NPN transistor Q2, NPN transistor Q1 and normally open relay K1, the positive electrode of the diode D5 is connected to the surge voltage protection signal AC_OVP, the negative electrode of the diode D5 is connected to the base of the NPN transistor Q2 through the resistor R8, the emitter of the NPN transistor Q2 is connected to the output ground PGND, the base and emitter of the NPN transistor Q2 are connected in parallel with a resistor R10, the collector of the NPN transistor Q2 is connected to the base of the NPN transistor Q1, the collector of the NPN transistor Q1 is connected to the power supply port VCC, the emitter of the NPN transistor Q1 is connected to the coil of the normally open relay K1 through the resistor R4, and the base and collector of the NPN transistor Q1 are connected in parallel with a resistor R6.

[0028] The normally open relay K1 includes antenna 1, antenna 2, antenna 3 and antenna 4, wherein the antenna 1 and antenna 2 are connected to the live wire L of the power grid, the antenna 3 is connected to the resistor R4, and the antenna 4 is connected to the output ground PGND.

[0029] Specifically, see Figure 1 The rectifier bridge BD1 includes a contact 1, a contact 2, a contact 3 and a contact 4, wherein the contact 1 and the contact 4 are connected to both ends of the capacitor C1, the contact 2 is connected to the antenna 2, and the contact 3 is connected to the neutral line N of the power grid.

[0030] In this embodiment, ports L and N are the live wire and neutral wire of the power grid; port VCC is the internal auxiliary power supply of the OBC, and the reference ground is the output ground PGND of the rectifier bridge BD1.

[0031] In the grid voltage sampling and diagnosis circuit, the circuit samples the grid voltage through a sampling circuit composed of rectifier diodes D2, D3, voltage-dividing resistors R7, R9, R12, R19 and filter capacitor C3, and is connected to the positive input terminal of the comparator U1A through resistor R16; port VCC is connected to the negative input terminal of the comparator U1A through voltage-dividing resistors R18, R21 and filter capacitor C5, which is used to set the protection threshold; once the sampled grid voltage exceeds the protection threshold, the comparator U1A outputs a high level, which is filtered by an RC filter circuit composed of resistor R17 and capacitor C4, and then output to a latch circuit composed of PNP transistor Q3, NPN transistor Q4 and resistors R11, R13, R15, R20;

[0032] After the high level enters the latch circuit, the base of the NPN transistor Q4 is pulled up, so that Q4 is saturated and turned on; the emitter of Q4 is connected to the reference ground PGND, and the collector of Q4 is connected to the base of the PNP transistor Q3 through R15. Therefore, Q4 is saturated and turned on, which pulls the base of Q3 down, so that Q3 is also saturated and turned on; the emitter of Q3 is connected to the power supply port VCC, and after Q3 is saturated and turned on, its collector will output a surge voltage protection signal AC_OVP that is always high.

[0033] In the switch control circuit that controls the on and off of the input power grid, the surge voltage protection signal AC_OVP is connected to the anode of the diode D5, the cathode of D5 is connected to the base of the NPN transistor Q2 through the resistor R8, the emitter of Q2 is connected to the reference ground PGND, and the collector of Q2 is connected to the base of the NPN transistor Q1.

[0034] When OBC starts and works normally, the input surge protection is not triggered, and the surge voltage protection signal AC_OVP is at a low level. At this time, Q2 is cut off and Q1 is saturated and turned on. The power supply port VCC supplies power to the normally open relay K1 to turn on K1, and OBC can be connected to the grid and work normally.

[0035] When the input surge protection is triggered, the surge voltage protection signal AC_OVP is always at a high level, Q2 is saturated and turned on to pull down the base of Q1, so that Q1 is turned off, thereby closing the relay K1 and disconnecting the OBC from the grid.

[0036] The above description is only a preferred embodiment of the present invention, and the printed data cable is not intended to limit the present invention. Any modification, equivalent replacement or improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An OBC surge voltage protection circuit, characterized in that: It includes a grid voltage sampling and diagnosis circuit and a switch control circuit connected thereto for controlling the on / off of an input grid. The front section of the grid voltage sampling and diagnosis circuit is connected to a grid live line L and a neutral line N, and the rear section of the switch control circuit is connected to a rectifier bridge BD1, which is connected to an output ground PGND. The grid voltage sampling and diagnosis circuit includes: a sampling circuit module for sampling the grid voltage, a diagnostic circuit module for diagnosing the grid voltage, and a latch circuit module for outputting a surge voltage protection signal. An RC filter circuit module is provided between the voltage diagnostic circuit module and the latch circuit module, and the surge voltage protection signal is connected to the switch control circuit.

2. The OBC surge voltage protection circuit according to claim 1, characterized in that: The sampling circuit module includes rectifier diodes D2, D3, voltage-dividing resistors R7, R9, R12, R19 and a filter capacitor C3. The positive electrodes of the diodes D2 and D3 are respectively connected to the live wire L and the neutral wire N of the power grid, and the negative electrodes are connected to one end of the resistor R7. The resistors R7, R9, R12 and R19 are connected in series in sequence. The other end of the resistor R19 is connected to the output ground PGND and is grounded. The filter capacitor C3 is connected in parallel to both ends of the resistor R19.

3. An OBC surge voltage protection circuit as claimed in claim 2, characterized in that: The diagnostic circuit module includes resistors R14, R16, R18, R21, capacitor C5 and comparator U1A, one end of the resistor R16 is connected between resistors R19 and R12, the other end of the resistor R16 is connected to the positive input end of the comparator U1A, the negative input end of the comparator U1A is connected to resistor R18, the other end of the resistor R18 is connected to the power supply port VCC, one end of the filter capacitor C5 and one end of the resistor R21 are connected between the resistor R18 and the comparator U1A in sequence, the other end of the filter capacitor C5 and the other end of the resistor R21 are both connected to the output ground PGND, one end of the resistor R14 is connected to the power supply port VCC, and the other end of the resistor R14 is connected to the output end of the comparator U1A.

4. The OBC surge voltage protection circuit according to claim 1, characterized in that: The RC filter circuit module includes a resistor R17 and a capacitor C4. The resistor R17 is connected to the output end of the comparator U1A. One end of the capacitor C4 is connected to the resistor R17, and the other end is connected to the output ground PGND.

5. An OBC surge voltage protection circuit as claimed in claim 4, characterized in that: The latch circuit module includes a PNP transistor Q3, an NPN transistor Q4 and resistors R11, R13, R15 and R20. A capacitor C2 is connected between the base and emitter of the PNP transistor Q3, the emitter of the PNP transistor Q3 is connected to the power supply port VCC, the collector of the PNP transistor Q3 is connected to one end of the resistor R13, the other end of the resistor R13 is connected to one end of the resistor R20, the other end of the resistor R20 is connected to the output ground PGND, the collector of the NPN transistor Q4 is connected to the base of the PNP transistor Q3 through the resistor R15, a resistor R11 is connected between the resistor R15 and the power supply port VCC, both ends of the resistor R11 are connected in parallel with the capacitor C2, the base of the NPN transistor Q4 is connected to the resistor R17, the emitter is connected to the output ground PGND, and the collector of the PNP transistor Q3 outputs a surge voltage protection signal.

6. The OBC surge voltage protection circuit according to claim 1, characterized in that: The switch control circuit includes diodes D5, D1, resistors R4, R6, R8, R10, NPN transistor Q2, NPN transistor Q1 and normally open relay K1, the positive electrode of the diode D5 is connected to the surge voltage protection signal, the negative electrode of the diode D5 is connected to the base of the NPN transistor Q2 through the resistor R8, the emitter of the NPN transistor Q2 is connected to the output ground PGND, the base and emitter of the NPN transistor Q2 are connected in parallel with resistor R10, the collector of the NPN transistor Q2 is connected to the base of the NPN transistor Q1, the collector of the NPN transistor Q1 is connected to the power supply port VCC, the emitter of the NPN transistor Q1 is connected to the coil of the normally open relay K1 through the resistor R4, and the base and collector of the NPN transistor Q1 are connected in parallel with resistor R6.

7. An OBC surge voltage protection circuit as claimed in claim 6, characterized in that: The normally open relay K1 includes antenna 1, antenna 2, antenna 3 and antenna 4. The antenna 1 and antenna 2 are connected to the live wire L of the power grid, the antenna 3 is connected to the resistor R4, and the antenna 4 is connected to the output ground PGND.

8. An OBC surge voltage protection circuit as claimed in claim 7, characterized in that: The rectifier bridge BD1 includes a contact 1, a contact 2, a contact 3 and a contact 4, wherein the contact 1 and the contact 4 are connected to two ends of the capacitor C1, the contact 2 is connected to the antenna 2, and the contact 3 is connected to the neutral line N of the power grid.

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