Battery reverse connection protection circuit of charger

Abstract

The utility model discloses a battery reverse connection protection circuit of a charger, the charger is used for charging a battery connected to a battery interface of the charger, and the protection circuit comprises a first relay, a positive temperature coefficient thermistor, a first charging starting switch and a control circuit; a switch of the first relay is connected in series with the preceding stage of the battery interface so as to control the charging of the battery; the positive temperature coefficient thermistor is connected in parallel with a switch of the first relay; the first charging starting switch is connected in series in a power supply path of a coil of the first relay; the control circuit is connected with the first charging starting switch and is used for conducting the first charging starting switch in a delayed manner when the battery needs to be charged; according to the utility model, the charger can be protected, and the charger is prevented from being damaged due to reverse connection of the battery.

Description

Technical Field

[0001] The utility model relates to the field of battery management, in particular to a battery reverse connection protection circuit of a charger. Background Art

[0002] Many batteries used nowadays are lithium batteries. Lithium batteries use a protection board inside, which will shut down the battery output in some cases. The battery charger needs to be charged to activate the battery. As a result, the battery charger cannot determine whether the polarity of the connected battery is correct without outputting. The charger adds a first relay on the output positive line to control the conduction and shutdown between the charger and the battery. After the output appliance starts normal output, the battery is reversed at the charger output end. The battery will release a current close to that when the battery is short-circuited into the charger. This current will be particularly large, and since the charger cannot disconnect the first relay in time, the charger will be damaged.

[0003] The above information disclosed in this Background section is included only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is currently known to a person of ordinary skill in the art. Utility Model Content

[0004] The technical problem to be solved by the present invention is that, in view of the defect in the prior art that after the output relay is turned on, the charger will not be able to promptly and effectively protect against the reverse battery phenomenon, and then the reverse battery after the charger turns on the output will cause damage to the charger, a battery reverse connection protection circuit for the charger is provided.

[0005] The technical solution adopted by the present invention to solve its technical problems is: constructing a battery reverse connection protection circuit for a charger, wherein the charger is used to charge a battery connected to its battery interface, and the protection circuit includes a first relay, a positive temperature coefficient thermistor, a first charging start switch, and a control circuit; the switch of the first relay is connected in series to the front stage of the battery interface to control the charging of the battery; the positive temperature coefficient thermistor is connected in parallel with the switch of the first relay; the first charging start switch is connected in series in the power supply path of the coil of the first relay; and the control circuit is connected to the first charging start switch for delaying the conduction of the first charging start switch when the battery needs to be charged.

[0006] Furthermore, in the battery reverse connection protection circuit of the charger described in the present invention, the control circuit includes a control chip and a delay circuit. The delay circuit is connected between the control chip and the control end of the first charging start switch. The control chip outputs a charging start signal when the battery needs to be charged. The delay circuit delays turning on the first charging start switch after receiving the charging start signal.

[0007] Furthermore, in the battery reverse connection protection circuit of the charger described in the present invention, the control circuit includes a control chip and a delay circuit, the delay circuit includes a capacitor, a resistor, and a diode, the first end of the resistor is connected to the control chip to receive a charging start signal, the second end of the resistor is grounded via the capacitor, the second end of the resistor is also connected to the cathode of the diode, and the anode of the diode is connected to the control end of the first charging start switch.

[0008] Furthermore, the battery reverse connection protection circuit of the charger described in the present invention also includes a first freewheeling diode connected in parallel with the coil of the first relay, which is used to provide a circuit for releasing energy on the coil of the first relay when the first charging start switch is disconnected.

[0009] Furthermore, in the battery reverse connection protection circuit of the charger described in the present invention, the first end of the coil of the first relay is connected to the power supply, and the second end is grounded via the first charging start switch, and the control end of the first charging start switch is connected to the control circuit.

[0010] Furthermore, the battery reverse connection protection circuit of the charger described in the present invention also includes a reverse connection detection circuit, which is connected to the battery interface and is used to detect the voltage and / or current of the battery interface to realize reverse connection detection of the battery; the control circuit is also connected to the reverse connection detection circuit and is used to disconnect the first charging start switch when the reverse connection detection circuit detects that the battery is reversely connected.

[0011] Furthermore, in the battery reverse connection protection circuit of the charger described in the present invention, the reverse connection detection circuit includes a first detection resistor, a second detection resistor, and a third detection resistor. The second detection resistor and the third detection resistor are connected in series between the positive and negative poles of the battery interface. The first end of the first detection resistor is connected between the second detection resistor and the third detection resistor. The first end of the first detection resistor is also connected to the control circuit, and the second end of the first detection resistor is connected to the power supply.

[0012] Furthermore, in the battery reverse connection protection circuit of the charger described in the present invention, the switch of the first relay is connected in parallel with the positive temperature coefficient thermistor and then in series with the main switch before the battery interface. The main switch is controlled by the control circuit and is used to be turned on before the first charging start switch when the battery needs to be charged.

[0013] Furthermore, the battery reverse connection protection circuit of the charger of the present invention further includes a second relay and a second charging start switch, wherein the switch of the second relay serves as the main switch;

[0014] The second charging start switch is connected in series in the power supply path of the coil of the second relay; the control circuit is connected to the second charging start switch and is used to output a charging start signal to turn on the second charging start switch when the battery needs to be charged.

[0015] Furthermore, the battery reverse connection protection circuit of the charger described in the present invention also includes a second freewheeling diode connected in parallel with the coil of the second relay, which is used to provide a circuit for releasing energy on the coil of the second relay when the second charging start switch is disconnected.

[0016] The battery reverse connection protection circuit of the charger of the present invention has the following beneficial effects: based on the present invention, when the battery needs to be charged, the first charging start switch is turned on with a delay. Before the first charging start switch is turned on, if the polarity of the connected battery is incorrect, the battery will release energy into the charger. At this time, since the positive temperature coefficient thermistor is connected in series in the circuit, the current in the circuit will be limited. Moreover, the heat generated by the current flowing through the positive temperature coefficient thermistor will cause its own temperature to rise. The resistance of the positive temperature coefficient thermistor increases with the temperature rising. The increase in resistance further limits the current in the circuit. In this way, the charger can be protected and damage to the charger caused by the reverse connection of the battery can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only embodiments of the present invention. Those skilled in the art can obtain other drawings based on the provided drawings without inventive work.

[0018] Figure 1 This is a circuit diagram of the first embodiment of the battery reverse connection protection circuit of the charger of the utility model;

[0019] Figure 2 It is a schematic diagram of the reverse connection detection circuit;

[0020] Figure 3 This is a circuit principle diagram of the second embodiment of the battery reverse connection protection circuit of the charger of the utility model. DETAILED DESCRIPTION

[0021] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the relevant drawings. Typical embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of the present application, rather than limitations on the technical solutions of the present application. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0022] Example 1

[0023] refer to Figure 1 The charger includes an AC / DC or DC / DC circuit, an output capacitor C1, and a battery interface. The output capacitor C1 is connected between the positive output terminal and the negative output terminal (i.e., GND) of the AC / DC or DC / DC circuit. The battery interface includes a positive pole and a negative pole. VAD_Bat in the figure represents the positive pole. The positive pole of the battery interface is connected to the positive output terminal of the AC / DC or DC / DC circuit, and the negative pole of the battery interface is connected to the negative output terminal of the AC / DC or DC / DC circuit, i.e., GND. The charger is used to charge the battery 100 connected between the positive and negative poles of its battery interface.

[0024] The battery reverse polarity protection circuit of the charger in this embodiment includes a first relay 1, a positive temperature coefficient thermistor R1, a first charging start switch Q1, and a control circuit. The positive temperature coefficient thermistor R1 has a resistance of approximately 1K at room temperature. The switch K1 of the first relay 1 is connected in series with the upstream of the battery interface to control the charging of the battery 100; the positive temperature coefficient thermistor R1 is connected in parallel with the switch K1 of the first relay 1; the first charging start switch Q1 is connected in series with the power supply path of the coil RLY1 of the first relay 1; and the control circuit is connected to the first charging start switch Q1 to delay turning on the first charging start switch Q1 when charging of the battery 100 is required.

[0025] To delay the turn-on of the first charge start switch Q1, the control circuit can directly use the control chip to delay sending a signal to the first charge start switch Q1, or it can use a delay circuit. In this embodiment, the control circuit includes a control chip and a delay circuit 3. The control chip can be a single-chip microcomputer. The delay circuit 3 is connected between the control chip and the control terminal of the first charge start switch Q1. The control chip outputs a charge start signal when the battery 100 needs to be charged. After receiving the charge start signal, the delay circuit 3 delays the turn-on of the first charge start switch Q1.

[0026] Specifically, the delay circuit 3 includes a capacitor C2, a resistor R2, and a diode ZD1. The first end of the resistor R2 is connected to the control chip to receive the charging start signal, the second end of the resistor R2 is grounded via the capacitor C2, and the second end of the resistor R2 is also connected to the cathode of the diode ZD1. The anode of the diode ZD1 is connected to the control end of the first charging start switch Q1.

[0027] The switch K1 of the first relay 1 is specifically connected in series between the positive terminal of the battery connector and the positive terminal of the output capacitor C1. The first end of the coil RLY1 of the first relay 1 is connected to the power supply VCC (VCC is the operating power supply of the chip in the charger). The second end of the coil RLY1 of the first relay 1 is grounded via the first charge start switch Q1. The control end of the first charge start switch Q1 is connected to the control circuit. Specifically, the first charge start switch Q1 is an NPN transistor, with its collector connected to the second end of the coil RLY1 of the first relay 1, its emitter grounded, and its base connected to the control circuit to receive the charge start signal.

[0028] The battery reverse connection protection circuit of this embodiment further includes a first freewheeling diode D1 connected in parallel with the coil RLY1 of the first relay 1 to provide a circuit for releasing energy from the coil RLY1 of the first relay 1 when the first charging start switch Q1 is disconnected.

[0029] After sending the charge start signal, the control chip detects whether the battery 100 is reversely connected. Specifically, the battery reverse connection protection circuit of this embodiment also includes a reverse connection detection circuit 3, which is connected to the battery interface and is used to detect the voltage and / or current of the battery interface to detect the reverse connection of the battery 100. The control circuit is also connected to the reverse connection detection circuit 3 and is used to disconnect the first charge start switch Q1 when the reverse connection detection circuit 3 detects that the battery 100 is reversely connected.

[0030] Specifically, the reverse connection detection circuit 3 includes a first detection resistor R3, a second detection resistor R4, and a third detection resistor R5. The second detection resistor R4 and the third detection resistor R5 are connected in series between the positive and negative electrodes of the battery interface. The first end of the first detection resistor R3 is connected between the second detection resistor R4 and the third detection resistor R5. The first end of the first detection resistor R3 is also connected to the voltage detection pin of the control chip, and the second end of the first detection resistor R3 is connected to the power supply VCC_mcu. R3 and R5 have the same resistance value, so it can detect whether the battery is reversely connected.

[0031] The working principle of this embodiment is as follows:

[0032] like Figure 1 As shown, at the beginning, transistor Q1 is disconnected and coil PLY1 of relay 1 is not powered, so transistor Q1 is disconnected. When the battery interface is connected to the battery, the control chip outputs a charging start signal, which charges capacitor C2 through resistor R2. Since switch K1 of relay 1 is disconnected at this time, it is equivalent to the battery interface of the charger being connected in series with a resistor R1. When the voltage on capacitor C2 is charged to a level that can break through diode ZD1, transistor Q1 is turned on, coil PLY1 of relay 1 is energized, and switch K1 of relay 1 is turned on. The period from the start of outputting the charging start signal to the turn-on of switch K1 is recorded as the buffer stage.

[0033] In the buffer stage, if the polarity of the connected battery 100 is correct, the charger will charge the battery through the resistor R1. At this time, the charger can detect that a normal battery is connected and enter the normal charging state.

[0034] During the buffer phase, if the connected battery 100 needs to be activated, the charger will also provide a certain charging current to the battery 100 through the resistor R1 to activate the battery 100. At the same time, the voltage clamping of the battery 100 also allows the charger to identify that the correct battery is connected. At this time, the relay is turned on to carry out normal charging.

[0035] During the buffer phase, if the polarity of the connected battery 100 is incorrect, the battery 100 will release energy into the charger. At this time, due to the series connection of resistor R1 in the circuit, the current in the circuit will be limited. Furthermore, the heat generated by the current flowing through resistor R1 will cause its temperature to rise. As the temperature rises, the resistance of resistor R1 increases. This increase in resistance further limits the current in the circuit, thus protecting the charger and preventing damage caused by reverse connection of the battery 100. Furthermore, during this process, the charger recognizes that the battery 100 is connected incorrectly and inverts the level of the charge start signal, preventing the switch K1 from closing.

[0036] Example 2

[0037] Unlike the first embodiment, in this embodiment, the switch K1 of the first relay 1 is connected in parallel with the positive temperature coefficient thermistor R1 and then in series with the main switch before the battery interface. The main switch is controlled by the control circuit and is configured to be turned on immediately when the battery 100 needs to be charged, that is, before the first charging start switch Q1 is turned on.

[0038] Specifically, this embodiment further includes a second relay 2 and a second charge start switch Q2. The switch K2 of the second relay 2 serves as the master switch. The second charge start switch Q2 is connected in series with the power supply path of the coil RLY2 of the second relay 2. The control circuit is connected to the second charge start switch Q2 and is configured to output a charge start signal to turn on the second charge start switch Q2 when charging of the battery 100 is required.

[0039] Specifically, the first end of coil RLY2 of second relay 2 is connected to power supply VCC. The second charge start switch Q2 utilizes an NPN transistor, with its collector connected to the second end of coil RLY2 of second relay 2, its emitter grounded, and its base connected to the control chip to receive the charge start signal. A second freewheeling diode D2 is also connected in parallel with coil RLY2 of second relay 2 to provide a circuit for dissipating energy from coil RLY2 of second relay 2 when the second charge start switch Q2 is disconnected.

[0040] The working process of this embodiment differs from that of the first embodiment in that after the control chip outputs the charging start signal, the switch K2 of the relay 2 is immediately turned on. During the buffering stage, if it is detected that the battery 100 is reversely connected, Q2 can be quickly turned off by directly reversing the charging start signal, so that the switch K2 will also be turned off immediately, ensuring that the connection with the battery is disconnected immediately when the battery is reversed.

[0041] It should be noted that the term "connected" or "connected" as used herein includes not only directly connecting two entities but also indirectly connecting them through other entities that have a beneficial improvement effect. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this utility model belongs. The terms used herein in the specification of this utility model are only for the purpose of describing specific embodiments and are not intended to limit this utility model.

[0042] Terms containing ordinal numbers, such as "first" and "second," used in this specification may be used to describe various components, but these components are not limited by these terms. These terms are used solely to distinguish one component from another. For example, a first component may be named a second component, and similarly, a second component may be named a first component, without departing from the scope of the present invention.

[0043] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which are all within the protection of the present invention.

Claims

1. A battery reverse connection protection circuit for a charger, wherein the charger is used to charge a battery connected to its battery port, characterized in that: The protection circuit includes a first relay, a positive temperature coefficient thermistor, a first charging start switch, and a control circuit; the switch of the first relay is connected in series to the front stage of the battery interface to control the charging of the battery; the positive temperature coefficient thermistor is connected in parallel with the switch of the first relay; The first charging start switch is connected in series in the power supply path of the coil of the first relay; The control circuit is connected to the first charging start switch and is used for delaying turning on the first charging start switch when the battery needs to be charged.

2. The battery reverse connection protection circuit of the charger according to claim 1, characterized in that: The control circuit includes a control chip and a delay circuit. The delay circuit is connected between the control chip and the control end of the first charge start switch. The control chip outputs a charge start signal when the battery needs to be charged. After receiving the charge start signal, the delay circuit delays turning on the first charge start switch.

3. The battery reverse connection protection circuit of the charger according to claim 2, characterized in that: The delay circuit includes a capacitor, a resistor, and a diode. The first end of the resistor is connected to the control chip to receive a charging start signal. The second end of the resistor is grounded via the capacitor. The second end of the resistor is also connected to the cathode of the diode. The anode of the diode is connected to the control end of the first charging start switch.

4. The battery reverse connection protection circuit of the charger according to claim 1, characterized in that: The device further includes a first freewheeling diode connected in parallel with the coil of the first relay, for providing a circuit for releasing energy from the coil of the first relay when the first charging start switch is disconnected.

5. The battery reverse connection protection circuit of the charger according to claim 4, characterized in that: A first end of the coil of the first relay is connected to a power source, and a second end is grounded via the first charging start switch. A control end of the first charging start switch is connected to the control circuit.

6. The battery reverse connection protection circuit of the charger according to claim 1, characterized in that: The device further includes a reverse connection detection circuit, which is connected to the battery interface and is used to detect the voltage and / or current of the battery interface to detect reverse connection of the battery; the control circuit is also connected to the reverse connection detection circuit and is used to disconnect the first charging start switch when the reverse connection detection circuit detects that the battery is reversely connected.

7. The battery reverse connection protection circuit of the charger according to claim 6, characterized in that: The reverse connection detection circuit includes a first detection resistor, a second detection resistor, and a third detection resistor. The second detection resistor and the third detection resistor are connected in series between the positive and negative poles of the battery interface. The first end of the first detection resistor is connected between the second detection resistor and the third detection resistor. The first end of the first detection resistor is also connected to the control circuit, and the second end of the first detection resistor is connected to the power supply.

8. The battery reverse connection protection circuit of the charger according to claim 1, characterized in that: The switch of the first relay is connected in parallel with the positive temperature coefficient thermistor and then in series with the main switch before the battery interface. The main switch is controlled by the control circuit and is used to be turned on before the first charging start switch when the battery needs to be charged.

9. The battery reverse connection protection circuit of the charger according to claim 8, characterized in that: It also includes a second relay and a second charging start switch, wherein the switch of the second relay serves as the main switch; The second charging start switch is connected in series in the power supply path of the coil of the second relay; The control circuit is connected to the second charging start switch and is configured to output a charging start signal to turn on the second charging start switch when the battery needs to be charged.

10. The battery reverse connection protection circuit of the charger according to claim 9, characterized in that: The device further includes a second freewheeling diode connected in parallel with the coil of the second relay, for providing a circuit for releasing energy from the coil of the second relay when the second charging start switch is disconnected.

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