Control circuit of high-performance battery charging relay

Abstract

The utility model is applicable to the technical field of battery charging, and provides a control circuit and a control method of a high-performance battery charging relay, and the control circuit comprises a resistor R1, a diode VD3, a main relay K1, a diode VD1, an auxiliary relay K2, a diode VD2, a main relay control circuit, an auxiliary relay control circuit, a detection circuit (1), a detection circuit (2) and an equivalent capacitor Cout. The utility model aims to solve the problem that a contactor or a relay at a battery end is damaged or adhered due to overlarge current at the moment of actuation under various abnormal conditions.

Description

Technical Field

[0001] The utility model relates to the technical field of battery charging, in particular to a control circuit for a high-performance battery charging relay. Background Art

[0002] Currently, in the industry, a relay is basically connected in series at the battery charging port. Generally, the relay is directly controlled to be attracted and disconnected, such as Figure 1 , lacking effective control over the attracting action. Generally, before charging the battery, there is no large-capacity capacitor Cout at the output end of the charger. In this case, there will be no large current flowing through the charging relay when the relay is directly attracted instantaneously, so there will be no problem. However, when there is a relatively large-capacity capacitor at the output end of the charger and the voltage is low, or when the battery voltage Vbat_P is much higher than Vin_P, attracting the charging relay K1 will cause an excessive current at the moment of attraction, and there is a high possibility of damaging the relay contacts. In addition, in specific engineering sites with poor environments, there are frequently faults of adhesion of the charging relay or contactor at the battery end. Summary of the Utility Model

[0003] In view of the above problems, the utility model proposes a control circuit for a high-performance battery charging relay that can avoid damage or adhesion problems of the contactor or relay at the battery end due to excessive current at the moment of attraction under various abnormal conditions. At the same time, the charging output end for charging the battery can also be equipped with an output filter capacitor. A branch circuit composed of two contacts of an auxiliary relay K2, a diode VD3, and a resistor R1 is connected in parallel to the original main relay K1. The battery Vbat_P charges the charger output end Vin_P through the resistor R1, the auxiliary relay K2, and the diode VD3. The auxiliary relay K2 is selected as a small-current ordinary AC normally open relay or a DC normally open relay. Before each attraction of the main relay K1, the auxiliary relay K2 must be attracted first. The battery pre-charges the charger output end through the resistor R1, the auxiliary relay K2, and the diode VD3. The attraction of the main relay K1 is controlled by detecting the pressure difference between the two contacts of the main relay K1, eliminating the influence of the uncertain capacitance value of the capacitor Cout at the charger output end. In this way, due to the very low pressure difference between the two contacts of the main relay K1 before attraction, zero-voltage attraction of the two contacts of the main relay K1 is achieved, greatly reducing the current value flowing through its contacts at the moment of attraction of the main relay K1, and avoiding damage or adhesion of the contacts due to excessive current.

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

[0005] A control circuit for a high-performance battery charging relay. The control circuit includes: a resistor R1, a diode VD3, a normally open main relay K1 and a diode VD1 connected in anti-parallel across its control coil, a normally open auxiliary relay K2 and a diode VD2 connected in anti-parallel across its control coil, a main relay control circuit, an auxiliary relay control circuit, a detection circuit (1), a detection circuit (2), and an equivalent capacitor Cout at the output end of the charger.

[0006] Further, both the main relay K1 and the auxiliary relay K2 are normally open relays. One contact of the main relay K1 is connected to the positive output terminal Vin_P of the charger, one end of the capacitor Cout, one end of the detection circuit (1), and the cathode of the diode VD3. Another contact of the main relay K1 is connected to the positive terminal Vbat_P of the battery, one end of the detection circuit (2), and one end of the resistor R1. The anode of the diode VD3 is connected to one contact of the auxiliary relay K2, and another contact of the auxiliary relay K2 is connected to the other end of the resistor R1. The positive output terminal Vin_P of the charger is also the positive input terminal for battery charging.

[0007] Further, one end of the control coil of the main relay K1 is connected to the cathode of the diode VD1 and the power supply VCC, and the other end of the control coil of the main relay K1 is connected to the anode of the diode VD1 and the main relay control circuit.

[0008] Further, one end of the control coil of the auxiliary relay K2 is connected to the cathode of the diode VD2 and the power supply VCC, and the other end of the control coil of the auxiliary relay K2 is connected to the anode of the diode VD2 and the auxiliary relay control circuit.

[0009] Further, the negative input terminal Vin_N of the charger is connected to the other end of the capacitor Cout and the negative terminal Vbat_N of the battery. The negative terminal Vbat_N of the battery is also the working ground GNDS_D.

[0010] Further, the detection circuit (1) detects the voltage between the positive and negative output terminals of the charger, and the detection circuit (2) detects the voltage between the positive and negative terminals of the battery.

[0011] Further, the voltage signals detected by the detection circuit (1) and the detection circuit (2) are both transmitted to the BMS for calculation and then used for the control of the main relay K1 and the auxiliary relay K2.

[0012] Further, the main relay control circuit controls the closing and opening of the main relay K1, and the auxiliary relay control circuit controls the closing and opening of the auxiliary relay K2.

[0013] In addition, the main control unit circuit of the battery is required to manage the main relay control circuit and the auxiliary relay control circuit to ensure the realization of the above functions. The main control unit circuit of the battery is not specifically described here.

[0014] Furthermore, the working principle and control method of the present utility model are specifically described as follows:

[0015] Before the charger is normally connected and the charger outputs normally, first, the auxiliary relay control circuit makes the normally open relay K2 close, so that the battery Vbat_P can charge the equivalent capacitor Cout at the output end Vin_P of the charger through the branch formed by the resistor R1 in series with the auxiliary relay contact and the diode VD3.

[0016] The detection circuit (1) detects the voltage value Vin_P between the positive and negative output terminals of the charger in real time, and the detection circuit (2) detects the voltage value Vbat_P between the positive and negative terminals of the battery; when it is detected that the voltage Vin_P between the positive and negative output terminals of the charger rises to about 1V lower than the battery voltage Vbat_P, the battery control unit sends a normal closing signal to the main relay control circuit, and the main relay K1 closes. At the same time or with a slight delay, the battery control unit sends a normal opening signal to the auxiliary relay control circuit to disconnect the auxiliary relay K2, so as to ensure that the auxiliary relay K2 is in the closed state only during the period when the battery pre-charges the charger, and is in the open state at other times.

[0017] When an abnormal short circuit occurs at the output terminal of the charger, after the auxiliary relay K2 closes, the voltage at the output terminal of the charger will not rise, and the output terminal voltage remains approximately zero. Therefore, the voltage Vin_P detected by the detection circuit (1) at the output terminal of the charger will always remain at a very low voltage, and it cannot meet the condition that the voltage Vin_P between the positive and negative output terminals of the charger rises to about 1V lower than the battery voltage Vbat_P, and the main relay K1 will continue to be in the open state; thus, it can avoid the damage or adhesion of the contacts of the main relay K1 caused by closing the main relay K1 in this abnormal short circuit situation, and avoid damage to the battery.

[0018] In addition, when an abnormal short circuit occurs at the output terminal of the charger, the charger output short circuit warning function can also be realized. The battery control unit circuit starts timing from the moment when the auxiliary relay K2 closing signal is given. When the detection circuit (1) detects that the charger output voltage Vin_p is still approximately zero volts when the predetermined maximum charging time is reached, a charger output short circuit warning is reported.

[0019] Each time the main relay K1 closes, since the voltage difference across its contacts is lower than 1V and it is turned on approximately at zero voltage, it can effectively limit the current flowing through the contacts of the main relay K1 when the main relay K1 closes, and avoid the adhesion, damage or breakage of the main relay K1 caused by excessive instantaneous current, improving the reliability of the circuit.

[0020] Compared with the prior art, the advantages of the present utility model are:

[0021] High reliability 1: By adding a small number of electronic components, reasonable control of the battery charging port relay is achieved, eliminating the influence of the capacitor at the output end of the charger, ensuring zero-voltage closing between the two contacts of the battery charging relay, with a very small closing current, greatly reducing the current at the moment of main relay closing under abnormal conditions at the output end of the charger, solving the problem of relay contact adhesion or damage caused by excessive current at the moment of closing, and significantly improving the reliability of the battery charging relay;

[0022] High reliability 2: It can detect abnormal short circuits at the output of the charger, avoiding contact adhesion or damage of the charging relay caused by closing the battery charging relay under such abnormal short circuit conditions, and also avoiding damage to the battery, significantly improving the reliability.

[0023] Low loss: When the battery is in the state of waiting to be charged, both the main relay K1 and the auxiliary relay K2 are in the off state. Only the detection circuit (2) is connected to the battery, and the detection circuit (1) is in the off state, without consuming the electrical energy of the battery; the added sampling detection circuit has a large sampling resistance value and very low loss; the added auxiliary relay control circuit also does not consume any electrical energy when the battery is in the state of waiting to be charged; therefore, the overall circuit loss is very small, and the consumption of the battery energy in the state of waiting to be charged is also very small, which can be basically ignored compared with the loss of the battery BMS itself and the consumption of the battery electrical energy.

[0024] Low cost: The number of added electronic components is small, and the increased cost is very small.

[0025] Further cost reduction: The technical solution of the present utility model ensures zero-voltage closing between the two contacts of the battery charging relay. When the battery voltage is not very high, such as not exceeding 500V, an appropriate AC relay can be selected for the battery charging relay instead of an appropriate DC relay, which can also greatly reduce the cost.

[0026] Easy to implement: The circuit is simple and easy to implement. Description of the drawings

[0027] Figure 1 It is the schematic diagram of the prior art.

[0028] Figure 2 It is the principle block diagram of the present utility model.

[0029] Figure 3 Principle of the present utility model Figure 2 The circuit diagram of the embodiment. Detailed implementation manners

[0030] In order to make the technical means implemented by the present utility model clear, the following further elaborates the detailed implementation manners of the present utility model in conjunction with the drawings. The specific control unit circuit of the battery control system will not be further elaborated.

[0031] The technical solution of the present utility model Figure 2 is specifically implemented as follows:

[0032] The overall control circuit includes: resistor R1, diode VD3, normally open main relay K1 and diode VD1 connected in anti-parallel on its control coil, normally open auxiliary relay K2 and diode VD2 connected in anti-parallel on its control coil, main relay control circuit, auxiliary relay control circuit, detection circuit 1, detection circuit 2, equivalent capacitor Cout at the output end of the charger.

[0033] Specifically, referring to Figure 3 , both the main relay K1 and the auxiliary relay K2 are normally open relays. One contact of the main relay K1 is connected to the positive output terminal Vin_P of the charger, one end of the capacitor Cout, one end of the detection circuit 1, and the cathode of the diode VD3. Another contact of the main relay K1 is connected to the positive terminal Vbat_P of the battery, one end of the detection circuit 2, and one end of the resistor R1. The anode of the diode VD3 is connected to one contact of the auxiliary relay K2, and another contact of the auxiliary relay K2 is connected to the other end of the resistor R1. The positive output terminal Vin_P of the charger is also the positive input terminal for battery charging.

[0034] Further, the negative input Vin_N of the charger is connected to the other end of the capacitor Cout and the negative terminal Vbat_N of the battery. The negative terminal Vbat_N of the battery is also the working ground GNDS_D.

[0035] Further, the other end of the resistor R3 is connected to one end of the resistor R7, the other end of the resistor R7 is connected to one end of the resistor R11, and the other end of the resistor R11 and one end of the resistor R16 are connected to one end of the capacitor C5 to generate a sampling signal Vin_SE of the internal output voltage of the charger. The other end of the resistor R16 and the other end of the capacitor C5 are connected to the working ground GNDS_D.

[0036] Further, the other end of the resistor R4 is connected to one end of the resistor R5, the other end of the resistor R5 is connected to one end of the resistor R8, and the other end of the resistor R8 and one end of the resistor R10 are connected to one end of the capacitor C3 to generate a battery voltage detection signal Vbat_SE. The other end of the resistor R10 and the other end of the capacitor C3 are connected to the working ground GNDS_D.

[0037] Further, one end of the control wire coil of the main relay K1 is connected to the power supply VCC (+12VDC) and the cathode of the diode VD1. The anode of the diode VD1 is connected to the other end of the main relay control wire coil and the collector of the NPN transistor VT2. The base of the transistor VT2 is connected to one end of the resistor R6, one end of the resistor R9, and one end of the capacitor C2. The other end of the resistor R6 is connected to the control signal K1_DRV of the main relay K1. The emitter of the transistor VT2, the other end of the resistor R9, and the other end of the capacitor C2 are connected to the working ground GNDS_D.

[0038] Further, one end of the control wire coil of the auxiliary relay K2 is connected to the power supply VCC (+12VDC) and the cathode of the diode VD2. The anode of the diode VD2 is connected to the other end of the auxiliary relay control wire coil and the collector of the NPN transistor VT1. The base of the transistor VT1 is connected to one end of the resistor R12, one end of the resistor R2, and one end of the capacitor C1. The other end of the resistor R12 is connected to the control signal K2_DRV of the auxiliary relay K2. The emitter of the transistor VT1, the other end of the resistor R2, and the other end of the capacitor C1 are connected to the working ground GNDS_D.

[0039] This preferred technical solution Figure 2 The working principle of the embodiment is described as follows:

[0040] Before the charger is normally connected and the charger outputs normally, the battery control unit first outputs the control signal K2_DRV of the auxiliary relay K2 as a high level, and the auxiliary relay K2 is attracted. Thus, the positive terminal Vbat_P of the battery charges the equivalent capacitor Cout at the output terminal Vin_P of the charger through the circuit branch composed of the resistor R1 in series with the auxiliary relay contact and the diode VD3.

[0041] The detection circuit 1 detects the voltage value Vin_P between the positive and negative output terminals of the charger in real time to generate the charger output voltage detection signal Vin_SE, and the detection circuit 2 detects the voltage value Vbat_P of the positive and negative terminals of the battery to generate the battery voltage detection signal Vbat_SE.

[0042] The charger output voltage detection signal Vin_SE and the battery voltage detection signal Vbat_SE need to be transmitted to the control unit of the battery for calculation and judgment by the control unit.

[0043] When it is detected that the voltage Vin_P at the positive and negative output terminals of the charger rises to about 1V lower than the battery voltage Vbat_P, the battery control unit outputs a low-level control signal K2_DRV for the auxiliary relay K2, and the auxiliary relay K2 disconnects. At the same time, the battery control unit outputs a high-level control signal K2_DR1 for the main relay K1 to pull in the main relay K1. After that, if the charger is started to output again, the battery can be normally charged according to the charging characteristics required by the battery BMS system.

[0044] When an abnormal short circuit occurs at the output terminal of the charger, the voltage Vin_P at the output terminal of the charger continuously approaches zero and cannot meet the condition that the voltage Vin_P at the positive and negative output terminals of the charger rises to about 1V lower than the battery voltage Vbat_P. The main relay K1 will continue to be in the off state. If the main relay K1 still cannot be pulled in after the set maximum charging delay is reached, it is determined that the charger output is short-circuited and an alarm message is uploaded to the battery control system. Therefore, it is possible to avoid damage or adhesion of the contacts of the main relay K1 caused by pulling in the main relay K1 in this abnormal short-circuit situation and avoid damage to the battery.

[0045] Each time the main relay K1 is pulled in, since the voltage difference across its contacts is lower than 1V, it is approximately zero-voltage turn-on, which can effectively limit the current flowing through the contacts of the main relay K1 when the main relay K1 is pulled in, and avoid adhesion, damage or breakage of the main relay K1 caused by excessive instantaneous current, improving the reliability of the circuit.

[0046] The above is only the typical implementation mode of the present invention. The protection scope of the present invention is not limited to the above implementation mode. Any technical solution belonging to the principle of the present invention belongs to the protection scope of the present invention. For those skilled in the art, several improvements made without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A control circuit for a high performance battery charging relay, characterized in that: The control circuit includes a resistor R1, a diode VD3, a main relay K1, a diode VD1, an auxiliary relay K2, a diode VD2, a main relay control circuit, an auxiliary relay control circuit, a detection circuit 1, a detection circuit 2 and an equivalent capacitor Cout; one contact of the main relay K1 is connected to the positive output terminal Vin_P of the charger, one end of the equivalent capacitor Cout, the detection circuit 1 and the cathode of the diode VD3, another contact of the main relay K1 is connected to the positive terminal Vbat_P of the battery, the detection circuit 2 and one end of the resistor R1, the anode of the diode VD3 is connected to a contact of the auxiliary relay K2, the other contact of the auxiliary relay K2 is connected to the other end of the resistor R1, one end of the control line package of the main relay K1 is connected to the cathode of the diode VD1 and the power supply VCC, the other end of the control line package of the main relay K1 is connected to the anode of the diode VD1 and the main relay control circuit, and one end of the control line package of the auxiliary relay K2 is connected to the cathode of the diode VD2 and the power supply VCC, The other end of the control coil of the auxiliary relay K2 is connected to the anode of the diode VD2 and the auxiliary relay control circuit, and the negative input terminal Vin_N of the charger, the negative terminal Vbat_N of the battery, the other end of the equivalent capacitor Cout, the detection circuit 1 and the detection circuit 2 are all connected to GNDS_D.

2. The control circuit according to claim 1, 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 Vin_P of the charger. The capacitor C5 is connected in parallel to both ends of the resistor R16 and the connection end with the resistor R11 generates a sampling signal Vin_SE of the internal output voltage of the charger. The other end of the resistor R16 is connected to the detection circuit 2, the negative output terminal Vin_N of the charger, the negative terminal Vbat_N of the battery and GNDS_D.

3. The control circuit according to claim 2, characterized in that: The detection circuit 2 includes a resistor R4, a resistor R5, a resistor R8, a resistor R10 and a capacitor C3. The resistors R4, R5, R8 and R10 are connected in sequence and one end of the resistor R4 is connected to another contact of the relay K1 and the internal output positive terminal Vbat_P of the charger. The capacitor C3 is connected in parallel to both ends of the resistor R10 and the connection end with the resistor R8 to generate a sampling signal Vbat_SE of the internal output voltage of the charger. The other end of the resistor R10 is connected to the detection circuit 2, the negative output terminal Vin_N of the charger, the negative terminal Vbat_N of the battery and GNDS_D.

4. The control circuit according to any one of claims 1 to 3, characterized in that: The main relay control circuit includes a resistor R6, a resistor R9, a capacitor C2 and a transistor VT2, the collector of the transistor VT2 is connected to the anode of the diode VD1, the base of the transistor VT2 is connected to one end of the resistor R6, one end of the resistor R9 and one end of the capacitor C2, the other end of the resistor R6 is connected to K1_DRV of the main relay K1, and the emitter of the transistor VT2, the other end of the resistor R9 and the other end of the capacitor C2 are all connected to GNDS_D.

5. The control circuit according to claim 4, characterized in that: The auxiliary relay control circuit includes a resistor R2, a resistor R12, a capacitor C1 and a transistor VT1, the collector of the transistor VT1 is connected to the anode of the diode VD2, the base of the transistor VT1 is connected to one end of the resistor R12, one end of the resistor R2 and one end of the capacitor C1, the other end of the resistor R12 is connected to K2_DRV of the auxiliary relay K2, and the emitter of the transistor VT1, the other end of the resistor R2 and the other end of the capacitor C1 are all connected to GNDS_D.

6. The control circuit according to claim 4, characterized in that: The transistor VT2 is an NPN transistor.

7. The control circuit according to claim 5, characterized in that: The transistor VT1 is an NPN transistor.

8. The control circuit according to claim 1, characterized in that: The main relay K1 and the auxiliary relay K2 are both normally open relays.

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