Protection device for preventing reverse connection and reverse charging of output of charger

Abstract

The embodiment of the utility model provides a charger output anti-reverse connection and anti-reverse charging protection device, and belongs to the technical field of charging safety. The charger output anti-reverse connection and anti-reverse charging protection device comprises a relay arranged at the output end of a charger and used for executing connection / disconnection of a charging loop through actuation / disconnection; the relay is connected with a relay control circuit and is used for controlling the relay to be switched on or switched off along with the voltage state of the charging loop; the detection circuit is connected to the charging loop and used for responding to the voltage state of the charging loop; and the charging loop is also connected with the relay control circuit, and transmits the voltage state to a relay driving module of the relay control circuit in real time. According to the scheme of the utility model, complicated signal judgment is not needed, passive control is realized only by depending on the voltage state, the system complexity is reduced, the protection on the charger and the battery is enhanced, and the service life of equipment is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of charging safety technology, specifically to a protection device for preventing reverse connection and reverse charging of a charger output. Background Technology

[0002] Currently, there are many reverse connection protection circuits for charger outputs in the industry, but most of them control the switching on or off of the MOS by detecting the polarity of the output voltage to effectively protect against reverse battery connection. Such circuits are relatively expensive and have relatively high losses when dealing with high current or high voltage outputs. For medium to high voltage outputs, especially when the output current reaches tens of amperes or above, a controlled, compatible medium- to high-voltage DC contactor or high-voltage DC relay is sometimes connected in series at the output. However, this method has drawbacks: it requires more space, is more expensive, and is not as flexible or convenient to use. Furthermore, the lack of effective and reliable control over the contactor or DC relay can lead to contact damage, sticking, or other damage to the contactor and relay under certain circumstances. When the output relay is in the connected state (normally engaged or stuck), if the charger's output voltage is lower than the external battery voltage, the battery will discharge to the charger output, i.e., reverse current flow. If the output electrolytic capacitor or output rectifier diode fails and short-circuits under these circumstances, the abnormally large current will damage the battery or cause damage to the printed circuit board and other components. Summary of the Invention

[0003] Based on the above problems, the purpose of this utility model embodiment is to provide a protection device for charger output to prevent reverse connection and reverse flow.

[0004] To achieve the above objectives, this utility model provides a protection device for reverse connection and reverse backflow prevention at the charger output. The protection device includes: a relay disposed at the charger output terminal, used to activate / deactivate the charging circuit by engaging / disengaging; a relay control circuit connected to the relay, used to control the relay to engage or disengage according to the voltage state of the charging circuit; a detection circuit connected to the charging circuit, used to respond to the voltage state of the charging circuit; and the charging circuit is also connected to the relay control circuit, transmitting the voltage state to the relay drive module of the relay control circuit in real time.

[0005] Optionally, an anti-reverse current diode is provided between the charger output terminal and the relay.

[0006] Optionally, the relay is a normally open AC relay or a high-voltage DC relay.

[0007] Optionally, the relay control circuit includes: a freewheeling diode connected in parallel with the relay to absorb the reverse electromotive force when the relay is disconnected; the relay and the freewheeling diode are connected in parallel to a relay drive module to generate a continuous signal controlling the relay to turn on / off.

[0008] Optionally, the relay drive module is any one of the following: ULN chip, TPI chip, TLP chip, IR chip, and DRV chip.

[0009] Optionally, the detection circuit includes: a detection circuit 1 connected between the charger output terminal and the relay, used to detect the voltage of the charger output terminal relative to the working ground; and a detection circuit 2 connected between the relay and the battery, used to detect the voltage of the battery positive terminal relative to the working ground.

[0010] Optionally, a Schottky diode is connected between the detection circuit 2 and the relay drive module; the anode of the Schottky diode is connected to the negative terminal of the battery, and the cathode of the Schottky diode is connected to the output terminal of the detection circuit 2.

[0011] Optionally, the detection circuit 1 and the detection circuit 2 are provided with a voltage comparator circuit; the output terminal of the voltage comparator circuit is connected to the relay drive module.

[0012] Optionally, the detection circuit 1 includes: a resistor divider network consisting of multiple fixed resistors connected in series, and a capacitor connected in parallel with any fixed resistor.

[0013] Optionally, the detection circuit 2 includes: an operational amplifier and a resistor divider network; the resistor divider network is located at the input end of the detection circuit 2, and the other end is connected to the operational amplifier; a feedback voltage divider resistor is provided between the input and output of the operational amplifier to set the gain of the operational amplifier; and a filter capacitor is provided at the output end of the detection circuit 2.

[0014] Through the above technical solution, when the battery or charging circuit voltage is abnormal (such as reverse connection or insufficient voltage), the detection circuit can respond quickly and transmit the real-time voltage status to the relay control circuit. Based on the received voltage status signal, the relay control circuit controls the relay to engage or disengage via the drive module, thereby achieving effective control of the charging circuit. Under normal circumstances, the relay engages to ensure normal charging; however, when the voltage is abnormal or the battery is connected in reverse, the relay disengages, cutting off the charging circuit and effectively preventing equipment damage caused by backflow current. This design eliminates the need for complex signal judgment, relying solely on voltage status for passive control, reducing system complexity while enhancing protection for the charger and battery, and extending the equipment's lifespan.

[0015] Other features and advantages of this utility model embodiment will be described in detail in the following detailed description section. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0017] Figure 1 This is a schematic diagram of the structure of a charger output anti-reverse connection and anti-reverse flow protection device provided in one embodiment of the present invention;

[0018] Figure 2 This is a circuit diagram of a charger output protection device against reverse connection and reverse backflow provided in one embodiment of the present invention. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0020] In this embodiment of the utility model, unless otherwise stated, directional terms such as "up," "down," "left," and "right" generally refer to the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use.

[0021] The terms “first,” “second,” “third,” etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0022] The terms "horizontal," "vertical," and "sag" do not imply that a component must be absolutely horizontal, vertical, or sagging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0023] Furthermore, terms like "roughly" and "basically" are used to indicate that the content does not require absolute precision, but rather allows for a certain degree of deviation. For example, "roughly equal" does not simply mean absolute equality; in actual production and operation, achieving absolute "equality" is difficult, and a certain degree of deviation is generally present. Therefore, besides absolute equality, "roughly equal to" also includes the aforementioned situation where a certain degree of deviation exists. Using this as an example, in other cases, unless otherwise specified, terms like "roughly" and "basically" have similar meanings.

[0024] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0025] Please refer to Figure 1 This embodiment provides a protection device for reverse connection and reverse backflow prevention of a charger output. The protection device includes: a relay disposed at the charger output terminal, used to perform the conduction / disconnection of the charging circuit by engaging / disengaging; the relay is connected to a relay control circuit 40, used to control the engagement or disengagement of the relay according to the voltage state of the charging circuit; a detection circuit connected to the charging circuit, used to respond to the voltage state of the charging circuit; the charging circuit is also connected to the relay control circuit, and the charging circuit transmits the voltage state to the relay drive module of the relay control circuit in real time.

[0026] For chargers with output voltages ranging from low to high, a standard normally open AC relay or a high-voltage DC relay K1 can be selected. The relay K1 is controlled by detecting the battery terminal voltage Vbat_P. Since GND_D is the working ground, the voltage difference between the battery positive terminal Vbat_P and the battery negative terminal Vbat_N is Vbat_P. The polarity of the battery terminal voltage Vbat_P is determined to control the on / off state of relay K1. When a negative value is detected in the battery terminal voltage Vbat_P (i.e., the battery is reversed), relay K1 remains open, thus achieving reverse connection protection. When the battery is normally connected, the charger's internal output voltage Vout_P and the battery positive terminal voltage Vbat_P must be detected simultaneously. The voltage difference between the two is calculated. The relay K1 is only activated when the voltage difference is sufficiently low, such as less than 0.2V. Engaging relay K1 ensures zero-voltage switching between its two contacts, significantly reducing the current flowing through K1's contacts when it engages. This prevents the relay from sticking, being damaged, or failing due to excessive current, thus improving circuit reliability. Connecting a reverse-current protection diode in series at the output prevents reverse current or abnormally high current from flowing back into the battery during normal operation or when the charger output is abnormal. This improves the reliability of the output relay, prevents excessive current from burning out internal charger components or circuitry, and enhances battery protection and reliability.

[0027] To achieve the above objectives, the technical solution of this utility model Figure 1 The specific explanation is as follows:

[0028] A charger output protection device for reverse connection and reverse current protection includes: a detection circuit 1, a detection circuit 2, a relay control circuit, a reverse current protection diode VD2, an output relay K1 and a diode VD1 connected in reverse parallel on its control coil;

[0029] Furthermore, the anode of the anti-reverse current diode VD2 is connected to the charger output Vout_P and one end of the detection circuit 1, and the cathode of the diode VD2 is connected to one contact of the normally open relay K1. The other contact of the relay K1 is connected to the positive terminal Vbat_P of the battery and one end of the detection circuit 2.

[0030] Furthermore, the charger output negative terminal Vout_N is connected to the other end of detection circuit 1, the other end of detection circuit 2, the battery negative terminal Vbat_N, and the working ground GND_D;

[0031] Furthermore, one end of the relay K1 control coil is connected to the cathode of diode VD1 and the power supply VCC, and the other end of the relay K1 control coil is connected to the anode of diode VD1 and the relay control circuit.

[0032] Furthermore, detection circuit 1 detects the voltage Vout_P between the motor output Vout_P and the working ground GND_D, and detection circuit 2 detects the voltage Vbat_P between the positive terminal of the battery Vbat_P and the working ground GND_D.

[0033] Furthermore, the relay control circuit controls the activation and deactivation of relay K1;

[0034] In addition, the signals detected by detection circuit 1 and detection circuit 2 need to be sent to the charger's control unit circuit. The charger control unit circuit needs to determine the polarity of the battery voltage Vbat_P. When the battery is reverse-connected, the relay K1 is kept open to achieve reverse connection protection. When the battery is connected normally, the charger control unit circuit needs to compare the output Vout_P and the battery voltage Vbat_P and control the relay K1 to close appropriately according to the requirements. The charger control unit circuit also controls and implements the charger's standby mode, output soft start, normal operation, and shutdown functions. The specific judgment, calculation comparison, or other control functions of the charger control unit circuit will not be described in detail here.

[0035] Furthermore, the preferred working principle and control method of this utility model are specifically described below:

[0036] After the main control unit of the charger is working normally, the detection circuit 2 first detects the voltage Vbat_P at the battery terminal. When the battery is reversed, the detection circuit 2 will detect that the voltage Vbat_P is negative. In this case, the control relay circuit will keep the relay K1 in the open state, so that the reverse connection of the battery will not have any adverse effect on the reliability of the charger, and realize the reverse connection protection of the charger output.

[0037] When the battery is properly connected, detection circuit 2 detects a positive voltage Vbat at the battery terminal. The charger's main control unit, upon detecting that all other conditions are normal, initiates a soft start. When the charger's internal output voltage Vout rises to approximately 1V below the battery voltage Vbat, the main control unit sends a normal engagement signal to the relay control circuit, causing relay K1 to engage. This achieves zero-voltage engagement between the two contacts of relay K1, effectively limiting the current flowing through the relay K1 contacts when it engages, preventing the relay from sticking, being damaged, or failing due to excessive current. Then, the charger charges the battery normally. Theoretically, when the charger's internal output voltage Vout rises below the battery voltage, relay K1 engages. Because of the anti-reverse current diode VD2, the battery current can be prevented from flowing back into the relay. Therefore, the moment relay K1 engages, the current is essentially zero, but not zero-voltage. This control method is also possible, but it is not as reliable as ensuring that the relay engages when the voltage between the two contacts is essentially zero.

[0038] A reverse-current protection diode VD2 is connected in series at the output terminal to prevent reverse current from flowing back into the battery during normal operation and when there is an abnormal short circuit in the charger output rectifier diode or filter capacitor.

[0039] Compared with the prior art, the advantages of this utility model are:

[0040] By rationally controlling the charger output relay, a standard normally open relay with voltage compatibility can be selected, reducing cost and component size. Rational control of relay engagement enables zero-voltage engagement of the two contacts of relay K1, reducing the current flowing through them at the moment of engagement and preventing contact sticking damage caused by excessive current, significantly improving reliability. The anti-reverse current diode prevents reverse current or abnormally high current from flowing back into the battery during normal operation and when the charger output is abnormal. This not only improves the reliability of the output relay but also prevents internal components or circuits from burning out due to excessive current during abnormal output, thus improving battery protection and reliability. Furthermore, it reduces the accuracy requirements for differential voltage detection during relay engagement, facilitating effective control of relay engagement.

[0041] By rationally controlling the relay's engagement, zero-voltage engagement of the two contacts of relay K1 is achieved, avoiding relay engagement under high DC voltage. This allows the selection of a suitable ordinary AC relay, eliminating the need for DC contactors or DC relays, thus reducing component size and, crucially, significantly lowering component costs. Furthermore, for high-voltage output chargers, the output relay is disconnected momentarily due to input abnormality alarms, other faults, or normal charging stoppage. Therefore, the positive and negative pins of the output plug are not energized when the charger stops charging. Theoretically, for high-voltage chargers, the fast discharge circuit at the output end can be omitted. This fast discharge circuit requires high-voltage switching transistors or other switching elements, as well as high-power discharge resistors, and strict logic timing control to ensure on-demand fast discharge. However, by employing the aforementioned reverse connection and reverse current protection devices, only a simple low-power resistor is needed for slow discharge, improving reliability without the need for control, and appropriately reducing costs and size.

[0042] In one possible implementation, refer to Figure 2 The charger's internal positive output terminal Vout_P is connected to the anode of diode VD2 and one end of resistor R3. The cathode of diode VD2 is connected to one contact of relay K1. The other contact of relay K1 is connected to the battery positive 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 and one end of capacitor C5, generating the charger's internal output voltage sampling signal Vout_SE. The other ends of resistor R16 and capacitor C5 are connected to the working ground GNDS_A.

[0043] Furthermore, the charger output negative terminal Vout_N is connected to the battery negative terminal Vbat_N and the working ground GNDS_A;

[0044] 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 pin 5 of the non-inverting input of op-amp D1. The other end of resistor R9 is connected to the +3.3VDC power supply. The other ends of capacitor C6, resistor R15, capacitor C4, resistor R17, pin 4 of op-amp 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 resistor 4 is connected to the +5VDC power supply and pin 8 of the op-amp. 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 end of resistor R13, one end of resistor R6, one end of capacitor C3, and pin 6 of the inverting input of op-amp D1. The other end of capacitor C3 is connected to the other end of resistor R6, one end of resistor R4, and pin 7 of the output of op-amp D1. The other end of resistor R4 is connected to the other end of capacitor C2 and generates the battery voltage detection signal Vbat_SE.

[0045] Furthermore, one end of the relay control 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 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.

[0046] 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 its core. This digital control circuit judges the positive and negative polarity of the battery voltage Vbat_P. When the battery is reverse connected, the relay K1 is kept in the open state to realize reverse connection protection. When the battery is connected normally, this digital control circuit compares the output Vout_P and the battery voltage Vbat_P to control the relay K1 to be energized. This digital control circuit also controls and implements the standby mode, output soft start, normal operation and shutdown functions of the charger. The specific judgment, calculation comparison or other control functions of this digital control circuit will not be described in detail here.

[0047] The working principle of this embodiment is briefly explained as follows:

[0048] After the main control unit of the charger is working normally, it first detects the voltage Vbat_P at the battery terminal through the differential detection circuit composed of operational amplifier D1 and its surrounding sampling resistors. When the battery is reverse connected, the detected voltage Vbat_P is negative. In this case, the control relay circuit will keep the relay K1 in the open state to realize reverse connection protection, so that the reverse connection of the battery will not have any adverse effect on the reliability of the charger.

[0049] When the battery is connected normally, the voltage Vbat at the battery terminal is detected to be positive. The main control unit of the charger performs a soft start output when all 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 engagement to the relay control circuit. The relay K1 engages, thereby achieving zero-voltage engagement of the two contacts of the relay K1. This greatly reduces the current flowing through the contacts of the relay K1 when it engages, avoiding sticking, damage or failure of the relay due to excessive current. Then the charger charges the battery normally.

[0050] The anti-reverse current diode VD2 prevents reverse current from flowing back into the battery during normal operation and when the charger output is abnormal.

[0051] In addition, because this utility model has the ability to detect the internal output voltage and battery voltage, it can simultaneously detect abnormal conditions such as output overvoltage, undervoltage and short circuit, and send the detection signal to the charging control unit circuit for corresponding protection.

[0052] The above description is merely a typical embodiment of this utility model. The relay K1 described herein can be a contactor, a DC relay, or an AC relay. The specific location of the anti-reverse current diode in the circuit is not limited to the location shown in the diagram. The protection scope of this utility model is not limited to the above embodiments. All technical solutions that fall within the principle of this utility model are within its protection scope. For those skilled in the art, any improvements made without departing from the principle of this utility model should also be considered within its protection scope.

[0053] The optional embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present utility model, various simple modifications can be made to the technical solutions of the present utility model, and these simple modifications all fall within the protection scope of the present utility model.

[0054] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this embodiment.

[0055] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0056] Furthermore, various different implementation methods of this utility model can be arbitrarily combined, as long as they do not violate the spirit of this utility model, they should also be regarded as the content disclosed by this utility model.

Claims

1. A protection device for charger output to prevent reverse connection and reverse current flow, characterized in that, The charger output protection devices for reverse connection and reverse current prevention include: A relay installed at the output of the charger is used to turn the charging circuit on / off by engaging / disengaging it; The relay is connected to a relay control circuit, which controls the relay to engage or disengage according to the voltage state of the charging circuit; wherein, An anti-reverse current diode is provided between the output terminal of the charger and the relay; The relay is a normally open AC relay or a high-voltage DC relay; The relay control circuit includes: a freewheeling diode connected in parallel with the relay to absorb the reverse electromotive force when the relay is disconnected; the relay and the freewheeling diode are connected in parallel to the relay drive module to generate a continuous signal for controlling the relay to turn on / off. The relay drive module is any one of the following: ULN chip, TPI chip, TLP chip, IR chip, and DRV chip; A detection circuit connected to the charging circuit is used to respond to the voltage state of the charging circuit; The charging circuit is also connected to the relay control circuit, and the charging circuit transmits the voltage status to the relay drive module of the relay control circuit in real time.

2. The charger output protection device against reverse connection and reverse current leakage according to claim 1, characterized in that, The detection circuit includes: Detection circuit 1 is connected between the charger output terminal and the relay to detect the voltage of the charger output terminal relative to the working ground; Detection circuit 2 is connected between the relay and the battery and is used to detect the voltage of the positive terminal of the battery relative to the working ground.

3. The charger output reverse connection and reverse current protection device according to claim 2, characterized in that, A Schottky diode is connected between the detection circuit 2 and the relay drive module; The anode of the Schottky diode is connected to the negative terminal of the battery, and the cathode of the Schottky diode is connected to the output terminal of the detection circuit 2.

4. The charger output protection device against reverse connection and reverse current leakage according to claim 2, characterized in that, The detection circuit 1 and the detection circuit 2 are equipped with voltage comparator circuits; The output of the voltage comparator circuit is connected to the relay drive module.

5. The charger output protection device against reverse connection and reverse current leakage according to claim 2, characterized in that, The detection circuit 1 includes: It consists of a resistor voltage divider network consisting of multiple fixed resistors connected in series, and a capacitor connected in parallel with any fixed resistor.

6. The charger output protection device against reverse connection and reverse current leakage according to claim 2, characterized in that, The detection circuit 2 includes: Operational amplifier and resistor divider network; The resistor divider network is set at the input end of the detection circuit 2, and the other end is connected to the operational amplifier; A feedback voltage divider resistor is provided between the input and output of the operational amplifier to set the gain of the operational amplifier; A filter capacitor is installed at the output terminal of the detection circuit 2.

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