Charger output anti-reverse connection protection circuit

By using normally open AC relay K1 in the charger output anti-reverse protection circuit and controlling its on-off by detecting the voltage difference, the problems of high cost, large loss and insufficient control during medium and high voltage output in the prior art are solved, and the protection effect of higher reliability, better cost and lower loss is achieved.

CN222996257UActive Publication Date: 2025-06-17SHENZHEN HUARUI NEW ENERGY TECH CO LTD
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Patent Information

Application Number
CN202421709766.2
Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
Filing Date
2024-07-18
Publication Date
2025-06-17
Estimated Expiration
2034-07-18

AI Technical Summary

Technical Problem

The existing charger output anti-reverse protection circuit has high cost and high losses when outputting medium and high voltage. The medium and high voltage DC contactors or high voltage DC relays used have large space volume and high cost, and the control is not reliable enough, which can easily lead to electric shock damage, adhesion or damage to the contactors or relays.

Method used

The normally open AC relay K1 is used, and the on-off of the relay K1 is controlled by detecting the voltage at the battery end of the charger. The relay K1 is only attracted when the voltage difference between the output voltage and the battery voltage is less than 0.2V, ensuring that the two contacts of the two contacts are opened at zero voltage, reducing the current during the relay being absorbed and avoiding adhesion, damage or damage.

Benefits of technology

The charger output anti-reverse protection circuit with higher reliability, better cost and lower loss is achieved, which avoids adhesion, damage or damage caused by excessive current of the relay, improves the reliability of the circuit, reduces the component size and reduces the cost.

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Abstract

The utility model is suitable for the field of switching power supplies, and provides a charger output anti-reverse-connection protection circuit which is higher in reliability, better in cost and lower in loss, and the charger output anti-reverse-connection protection circuit comprises a detection circuit (1), a detection circuit (2), a relay control circuit, a relay K1 and a diode VD1, one contact of the relay K1 is connected with an internal output positive end VoutP of the charger and the detection circuit (1), the other contact of the relay K1 is connected with a positive end VbatP of a battery and the detection circuit (2), the diode VD1 is reversely arranged on a control coil of the relay K1, a cathode of the diode VD1 is connected with a power supply VCC, an anode of the diode VD1 is connected with the relay control circuit, and a cathode of the diode VD1 is connected with the detection circuit (2). The detection circuit (1) and the detection circuit (2) are both connected with a charger output negative end VoutN and battery negative ends VbatN and GNDD.
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Description

Technical Field

[0001] The utility model relates to the technical field of switching power supplies, and particularly relates to an anti-reverse connection protection circuit for the output of a charger. Background Art

[0002] At present, there are many anti-reverse connection protection circuits for the output of chargers in the industry. Most of them detect the voltage polarity at the output end to control the on or off of the MOS, so as to effectively protect against the situation of reverse connection of the battery at the output end. Such circuits have relatively high costs and relatively large losses when outputting large currents or high voltages. For medium and high voltage outputs, especially when the output current reaches dozens of amperes or more, a controlled and adapted medium and high voltage DC contactor or high voltage DC relay is also connected in series at the output end. The disadvantage of this method is that the space volume is relatively large and the cost is relatively high, resulting in less flexible and convenient use. There is no effective and reliable control over the contactor or DC relay, which may also cause contact damage, adhesion or damage of the contactor and relay under special circumstances. Content of the Utility Model

[0003] In view of the above problems, the utility model proposes an anti-reverse connection protection circuit for the output of a charger with higher reliability, better cost performance and lower loss. For chargers with an output voltage of several hundred volts or less, a general normally open AC relay K1 can be selected. By detecting the voltage Vbat_P at the battery terminal of the charger, since GND_D is the working ground, the voltage difference between the positive terminal Vbat_P of the battery and the negative terminal Vbat_N of the battery is Vbat_P. By judging the positive and negative polarity of the battery terminal voltage Vbat_P, the on and off of the relay K1 can be controlled. When it is detected that the battery terminal voltage Vbat_P is negative, that is, the battery is reversely connected, the relay K1 is maintained in the off state, and the output reverse connection protection can be realized. When the battery is normally connected, it is necessary to detect the internal output voltage Vout_P of the charger and the voltage Vbat_P at the positive terminal of the battery at the same time. By calculating the voltage difference between the two, the relay K1 is only energized when the voltage difference between the two is low enough, such as when the voltage difference is less than 0.2V, ensuring that the two contacts of the relay K1 are turned on at zero voltage, which can greatly reduce the current flowing through the contacts of the relay K1 when the relay K1 is energized, and avoid adhesion, damage or damage of the relay K1 caused by excessive current, thus improving the reliability of the circuit.

[0004] To achieve the above purpose, the specific description is as follows:

[0005] An anti-reverse connection protection circuit and control method for the output of a charger, including: a detection circuit (1), a detection circuit (2), a relay control circuit, a relay K1 and a diode VD1 connected in anti-parallel on its control wire coil;

[0006] Further, relay K1 is a normally open relay. One contact of relay K1 is connected to one end of the charger output Vout_P and the detection circuit (1), and the other contact of relay K1 is connected to one end of the battery positive terminal Vbat_P and the detection circuit (2).

[0007] Further, the charger output negative terminal Vout_N is connected to the other end of the detection circuit (1), the other end of the detection circuit (2), the battery negative terminal Vbat_N, and the working ground GND_D.

[0008] Further, one end of the control coil of relay K1 is connected to the cathode of diode VD1 and the power supply VCC, and the other end of the control coil of relay K1 is connected to the anode of diode VD1 and the relay control circuit.

[0009] Further, the detection circuit (1) detects the voltage Vout_P between the motor output Vout_P and the working ground GND_D, and the detection circuit (2) detects the voltage Vbat_P between the battery positive terminal Vbat_P and the working ground GND_D.

[0010] Further, the relay control circuit controls the energization and de-energization of relay K1.

[0011] In addition, the signals detected by the detection circuit (1) and the detection circuit (2) need to be sent to the control unit circuit of the charger. The control unit circuit of the charger needs to judge the positive and negative polarities of the battery voltage Vbat_P. When the battery is reversely connected, the relay K1 is kept in the off state to achieve reverse connection protection; when the battery is normally connected, the control unit circuit of the charger needs to compare the output Vout_P and the battery voltage Vbat_P and reasonably control the energization of relay K1 according to requirements; the control unit circuit of the charger simultaneously controls and realizes functions such as the standby mode, output soft start, normal operation, and shutdown of the charger. For the specific judgment, arithmetic comparison, or other control functions of the control unit circuit of the charger, no specific description is made here.

[0012] Further, the preferred working principle and control method of the present utility model are specifically described as follows:

[0013] After the main control unit of the charger works normally, first, the detection circuit (2) detects the voltage Vbat_P at the battery terminal. When the battery is reversely connected, the detection circuit (2) will detect that the voltage Vbat_P is negative. In this case, the control relay circuit will maintain the off state of relay K1, so that the reversely connected battery will not cause any adverse effects on the reliability of the charger, realizing reverse connection protection of the charger output;

[0014] When the battery is normally connected, the detection circuit (2) detects that the voltage Vbat at the battery terminal is positive. The main control unit of the charger performs output soft start when it detects that all other conditions are normal. When the output voltage Vout inside the charger rises to about 0.2V lower than the battery voltage Vbat, the main control unit circuit of the charger sends a signal for normal closing to the relay control circuit, and the relay K1 closes. Thus, zero-voltage closing of the two contacts of the relay K1 is achieved, effectively limiting the current flowing through the contacts of the relay K1 when the relay K1 closes, and avoiding adhesion, damage or breakage of the relay caused by excessive current. Then, the charger charges the battery normally.

[0015] Compared with the prior art, the advantages of the present utility model are:

[0016] Through reasonable control of the output relay K1 of the charger, the relay K1 can select a common normally open relay with voltage adaptation, reducing the cost and component size; through reasonable control of the closing of the relay K1, zero-voltage closing of the two contacts of the relay K1 is achieved, reducing the current flowing through the two contacts of the relay K1 during the closing moment, and avoiding the problem of adhesion and damage of the contacts of the relay K1 caused by excessive current during the closing moment, significantly improving the reliability.

[0017] Through reasonable control of the closing of the relay K1, zero-voltage closing of the two contacts of the relay K1 is achieved, avoiding the closing of the relay K1 under a large DC voltage. Thus, an adapted common AC relay can be selected, without the need to select a DC contactor or DC relay, which can reduce the component size, and more importantly, can also significantly reduce the component cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the principle block diagram of the present utility model.

[0019] Figure 2 is the circuit diagram of the embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] In order to make the technical means implemented by the present utility model clear, the following further elaborates the specific embodiments and working principles of the present utility model in conjunction with the drawings. Further elaboration on the realization of the output function of the charger and the specific control unit circuit will not be made.

[0021] As Figure 1 shown, the overall circuit includes: a detection circuit 1, a detection circuit 2, a relay control circuit, a relay K1, and a diode VD1 connected in anti-parallel on the control wire coil.

[0022] Specifically, referring to Figure 2, the positive output terminal Vout_P inside the charger is connected to one contact of relay K1 and one end of resistor R3. The other contact of relay K1 is connected to the positive battery terminal Vbat_P and one end of resistor R5. The other end of resistor R3 is connected to one end of resistor R7. The other end of resistor R7 is connected to one end of resistor R11. The other end of resistor R11 is connected to one end of resistor R16, one end of capacitor C5, and a sampling signal Vout_SE of the output voltage inside the charger is generated. The other ends of resistor R16 and capacitor C5 are connected to the working ground GNDS_A.

[0023] Furthermore, the negative output terminal Vout_N of the charger is connected to the negative battery terminal Vbat_N and the working ground GNDS_A.

[0024] Furthermore, the other end of resistor R5 is connected to one end of resistor R8. The other end of resistor R8 is connected to one end of resistor R10. The other end of resistor R10 is connected to one end of resistor R9, one end of resistor R15, one end of capacitor C6, and the non-inverting input pin 5 of operational amplifier D1. The other end of resistor R9 is connected to the power supply +3.3VDC. The other ends of capacitor C6, resistor R15, one end of capacitor C4, one end of resistor R17, pin 4 of operational amplifier D1, one end of capacitor C2, and one end of capacitor C4 are all connected to the working ground GNDS_A. The other end of capacitor C4 and pin 8 of the operational amplifier are connected to the power supply +5VDC. The other end of resistor R17 is connected to one end of resistor R14. The other end of resistor R14 is connected to one end of resistor R12. The other end of resistor R12 is connected to the other ends of resistor R13, one end of resistor R6, one end of capacitor C3, and the inverting input pin 6 of operational amplifier D1. The other end of capacitor C3 is connected to the other end of resistor R6, one end of resistor R4, and the output pin 7 of operational amplifier D1. The other end of resistor R4 is connected to the other end of capacitor C2 and a battery voltage detection signal Vbat_SE is generated.

[0025] Furthermore, one end of the relay control wire coil is connected to the power supply VCC (+12VDC) and the cathode of diode VD1. The anode of diode VD1 is connected to the other end of the relay control wire coil and the collector of NPN transistor VT1. The base of NPN transistor VT1 is connected to one end of resistor R1, one end of resistor R2, and one end of capacitor C1. The other end of resistor R1 is connected to the control signal K1_DRV of relay K1. The emitter of NPN transistor VT1, the other end of resistor R2, and the other end of capacitor C1 are connected to the working ground GNDS_A.

[0026] In addition, the signals detected by detection circuit 1 and detection circuit 2 need to be sent to the charger control unit circuit. The control unit circuit in this embodiment is a digital control circuit with a digital signal processor as the core. Through this digital control circuit, the positive and negative polarities of the battery voltage Vbat_P are judged. When the battery is reversely connected, the relay K1 is maintained in the open state to achieve reverse connection protection; when the battery is normally connected, this digital control circuit compares the output Vout_P with the battery voltage Vbat_P to control the attraction of the relay K1; this digital control circuit also controls and realizes functions such as the standby mode, output soft start, normal operation, and shutdown of the charger. Specific judgments, arithmetic comparisons, or other control functions of this digital control circuit are not elaborated here.

[0027] The working principle of this embodiment is briefly described as follows:

[0028] After the main control unit of the charger works normally, it first detects the voltage Vbat_P at the battery terminal through the differential detection circuit composed of the operational amplifier D1 and its surrounding sampling resistors. When the battery is reversely connected, the detected voltage Vbat_P is negative. In this case, the control relay circuit will maintain the relay K1 in the open state to achieve reverse connection protection, so that the reversely connected battery will not cause any adverse effects on the reliability of the charger.

[0029] When the battery is normally connected, the detected voltage Vbat at the battery terminal is positive. The main control unit of the charger performs output soft start when it detects that other conditions are normal. When the internal output voltage Vout of the charger rises to about 0.2V lower than the battery voltage Vbat, the main control unit circuit of the charger sends a high-level signal K1_DRV for normal attraction to the relay control circuit, and the relay K1 attracts, so as to realize the zero-voltage attraction of the two contacts of the relay K1, greatly reducing the current flowing through the contacts of the relay K1 when the relay K1 attracts, and avoiding adhesion, damage or damage of the relay caused by excessive current. Then the charger charges the battery normally.

[0030] In addition, because the present utility model has detections of the internal output voltage and the battery terminal voltage, it can simultaneously detect abnormal conditions such as output overvoltage, undervoltage, and short circuit, and send the detection signals to the charger control unit circuit for corresponding protection.

[0031] The above is only the typical implementation mode of the present utility model. The relay K1 described in the text can be a contactor, a DC relay, or an AC relay. The protection scope of the present utility model is not limited to the above implementation mode. Any technical solution belonging to the principle of the present utility model belongs to the protection scope of the present utility model. For those skilled in the art, several improvements made without departing from the principle of the present utility model should also be regarded as the protection scope of the present utility model.

Claims

1. A charger output anti-reverse connection protection circuit, characterized in that: The charger output reverse connection protection circuit includes a detection circuit 1, a detection circuit 2, a relay control circuit, a relay K1 and a diode VD1; one contact of the relay K1 is connected to the internal output positive terminal Vout_P of the charger and the detection circuit 1, and the other contact of the relay K1 is connected to the positive terminal Vbat_P of the battery and the detection circuit 2. The diode VD1 is reversely connected to the control line package of the relay K1 with the cathode connected to the power supply VCC and the anode connected to the relay control circuit. The detection circuit 1 and the detection circuit 2 are both connected to the negative terminal Vout_N of the charger output, the negative terminal Vbat_N of the battery and GND_D.

2. The charger output anti-reverse connection protection circuit according to claim 1, characterized in that: The relay control circuit includes a transistor VT1, a resistor R1, a resistor R2 and a capacitor C1, the collector of the transistor VT1 is connected to the anode of the diode VD1, the base of the transistor VT1 is connected to one end of the resistor R1, one end of the resistor R2 and one end of the capacitor C1, the other end of the resistor R2 is connected to the control signal K1_DRV of the relay K1, and the other end of the resistor R2, the other end of the capacitor C1 and the emitter of the transistor VT1 are all connected to GNDS_A.

3. The charger output anti-reverse connection protection circuit according to claim 2, characterized in that: The transistor VT1 is an NPN transistor VT1.

4. The charger output anti-reverse connection protection circuit according to any one of claims 1 or 2, characterized in that: The detection circuit 1 includes a resistor R3, a resistor R7, a resistor R11, a resistor R16 and a capacitor C5. The resistors R3, R7, R11 and R16 are connected in sequence and one end of the resistor R3 is connected to a contact of the relay K1 and the internal output positive terminal Vout_P of the charger. The capacitor C5 is connected in parallel to both ends of the resistor R16 and generates a sampling signal Vout_SE of the internal output voltage of the charger at the connection end with the resistor R11. The other end of the resistor R16 is connected to the detection circuit 2, the negative output terminal Vout_N of the charger, the negative terminal Vbat_N of the battery and GNDS_A.

5. The charger output anti-reverse connection protection circuit according to claim 4, characterized in that: The detection circuit 2 includes an operational amplifier D1, a resistor R4, a resistor R5, a resistor R6, a resistor R8, a resistor R9, a resistor R10, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R17, a capacitor C2, a capacitor C3, a capacitor C4 and a capacitor C6, one end of the resistor R5 is connected to another contact of the relay K1 and the positive terminal Vbat_P of the battery, the other end of the resistor R5 is connected to one end of the resistor R8, the other end of the resistor R8 is connected to one end of the resistor R10, the other end of the resistor R10 is connected to one end of the resistor R9, one end of the resistor R15, one end of the capacitor C6 and the non-inverting input pin 5 of the operational amplifier D1, the other end of the resistor R9 is connected to the power supply +3.3VDC, the other end of the capacitor C6, the other end of the resistor R15, the One end of capacitor C4, one end of the resistor R17, the 4th pin of the operational amplifier D1, one end of the capacitor C2 and one end of the capacitor C4 are all connected to GNDS_A, the other end of the capacitor C4 and the 8th pin of the operational amplifier D1 are all connected to the power supply +5VDC, the other end of the resistor R17 is connected to one end of the resistor R14, the other end of the resistor R14 is connected to one end of the resistor R12, the other end of the resistor R12 is connected to the other end of the resistor R13, one end of the resistor R6, one end of the capacitor C3 and the 6th pin of the reverse input of the operational amplifier D1, the other end of the capacitor C3 is connected to the other end of the resistor R6, one end of the resistor R4 and the 7th pin of the output of the operational amplifier D1, and the other end of the resistor R4 is connected to the other end of the capacitor C2 and generates a battery voltage detection signal Vbat_SE.

6. The charger output anti-reverse connection protection circuit according to claim 1, characterized in that: The relay K1 is a normally open relay.

7. The charger output anti-reverse connection protection circuit according to claim 1, characterized in that: The relay K1 is a contactor, a DC relay or an AC relay.