CN215646324U - Lithium battery charger output switch circuit with reverse connection protection function and charger - Google Patents
Lithium battery charger output switch circuit with reverse connection protection function and charger Download PDFInfo
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- CN215646324U CN215646324U CN202122329004.2U CN202122329004U CN215646324U CN 215646324 U CN215646324 U CN 215646324U CN 202122329004 U CN202122329004 U CN 202122329004U CN 215646324 U CN215646324 U CN 215646324U
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Abstract
The utility model relates to a lithium battery charger output switch circuit with a reverse connection protection function and a charger. The output switch circuit of the lithium battery charger comprises a relay circuit, an MOS (metal oxide semiconductor) tube, a sampling circuit and an MOS tube control circuit; the relay circuit comprises a relay switch; the first end of the relay switch is connected to the secondary winding, and the second end of the relay switch is used as the positive output end of the output circuit; the first pole and the second pole of the MOS tube are connected in parallel with two ends of the relay switch; the input end of the sampling circuit is connected with the output end of the output circuit; the output end of the sampling circuit inputs signals to the control chip; the first output end of the control chip controls the on or off of the relay switch; the second output end of the control chip is connected to the input end of the MOS tube control circuit, and the output end of the MOS tube control circuit is connected with the grid electrode of the MOS tube. The utility model also has the function of reverse connection protection under the condition of using the relay as the switch.
Description
Technical Field
The utility model relates to battery charging, in particular to an output switch circuit with a reverse connection protection function for a lithium battery charger.
Background
In the prior art, after the over-discharge protection of the lithium battery, the charging port of the lithium battery has no voltage, the charging MOS tube of the protection plate is closed, and the battery needs to be charged again, and the protection plate charging MOS tube needs to be forcibly opened to charge. There are two ways to open the protection board to charge the MOS transistor. One is that the charger adopts a direct output mode, and the other is that a pulse output mode is adopted. If the relay is used as an output switch in the charger, the direct output mode can be only used, the relay output is in a suction state, under the condition, when the charger is reversely connected with the battery, as shown in fig. 1, a discharging loop is formed at the negative electrode of the battery, the positive electrode output end of the charger, the switch K1, the secondary winding, the resistor R, the negative electrode output end of the charger and the positive electrode of the battery, and because the relay switching speed is slow, the contact cannot be timely disconnected, and the charger is easy to burn out.
SUMMERY OF THE UTILITY MODEL
Aiming at the defects of the prior art, the utility model discloses a lithium battery charger output switch circuit with a reverse connection protection function and a charger provided with the output switch circuit.
The technical scheme adopted by the utility model is as follows:
a lithium battery charger output switch circuit with a reverse connection protection function comprises a transformer; the transformer includes a secondary winding; the output circuit also comprises a relay circuit, an MOS tube, a sampling circuit and an MOS tube control circuit; the relay circuit comprises a relay switch; the first end of the relay switch is connected to the secondary winding, and the second end of the relay switch is used as the positive output end of the output circuit; the first pole and the second pole of the MOS tube are connected in parallel with two ends of the relay switch; the input end of the sampling circuit is connected with the output end of the output circuit; the output end of the sampling circuit inputs signals to the control chip; the first output end of the control chip controls the on or off of the relay switch; the second output end of the control chip is connected to the input end of the MOS tube control circuit, and the output end of the MOS tube control circuit is connected with the grid electrode of the MOS tube.
The relay circuit further comprises a relay coil, wherein the first end of the relay coil is connected with the collector of the first triode, and the emitter of the first triode is connected with a reference grounding end; the base electrode of the first triode is connected to the first output end of the control chip through a first resistor; the second end of the relay coil is connected to the operating voltage through a third resistor.
The further technical proposal is that the device also comprises an auxiliary winding; the MOS tube control circuit comprises an optical coupler; a second output end of the optical coupler is used as an output end of the MOS tube control circuit and is connected with a grid electrode of the MOS tube; the first output end of the optical coupler is connected with the output end of the auxiliary winding; a first input end of the optocoupler is connected to a second output end of the control chip; the second input end of the optocoupler is connected with the collector of the second triode, the emitter of the second triode is grounded, and the base of the second triode is connected with the output end of the output circuit.
The MOS tube control circuit further comprises a voltage division circuit, and the base electrode of the second triode is connected with the output end of the voltage division circuit; the input end of the voltage division circuit is connected with the output end of the output circuit.
The further technical scheme is that a second rectification voltage stabilizing circuit is connected between the auxiliary winding and the optocoupler.
The further technical proposal is that the sampling circuit comprises an operational amplifier; the output end of the output circuit is connected to the non-inverting input end of the operational amplifier through a tenth resistor; the inverting input end of the operational amplifier is connected to the reference ground end through an eleventh resistor, the inverting input end of the operational amplifier is connected to the output end of the operational amplifier through a twelfth resistor, and the output end of the operational amplifier is connected to the input end of the control chip through a thirteenth resistor.
The further technical scheme is that the sampling circuit comprises an amplifying chip; the model of the amplifying chip is LM 358; the output end of the output circuit is connected to the non-inverting input end of the amplifying chip through a tenth resistor; the inverting input end of the amplifying chip is connected to the reference ground end through an eleventh resistor, the inverting input end of the amplifying chip is connected to the output end of the amplifying chip through a twelfth resistor, and the output end of the amplifying chip is connected to the input end of the control chip through a thirteenth resistor.
The further technical scheme is that the model of the control chip is OB39R08A 3.
The further technical scheme is that a first rectifying and voltage stabilizing circuit is connected between a secondary winding of the transformer and an output circuit.
A lithium battery charger includes a transformer; the primary winding end of the transformer is connected with a charging power supply through an input circuit; the secondary side of the transformer comprises a secondary winding and an auxiliary winding; mounting the output circuit as described in any one of the above on the secondary side of the transformer; the output end of the output circuit is connected with the battery.
The utility model has the following beneficial effects:
the utility model uses the relay as the output switch of the lithium battery charger, and designs the reverse connection protection circuit on the basis. Specifically, the utility model adds a circuit which is connected with an MOS tube in series, under the condition of general no-load, the MOS tube is used for pulse output, at the moment, the relay is disconnected, and only when the current passes through the loop, the relay is closed and works normally. When the charger is reversely connected with the battery, the optocoupler in the MOS tube control circuit is matched with the triode, so that the charger has a reverse connection protection function, and can play a reverse connection protection role, and the relay is disconnected, so that a battery discharge loop is open, and the reverse connection protection role can be achieved.
Drawings
Fig. 1 is a schematic diagram of the prior art.
Fig. 2 is a circuit configuration block diagram of an embodiment of the present invention.
Fig. 3 is a circuit diagram of an embodiment of the present invention.
Detailed Description
The following describes embodiments of the present invention with reference to the drawings.
Fig. 2 is a circuit configuration block diagram of an embodiment of the present invention. As shown in fig. 2, the lithium battery charger includes a transformer T1, the primary winding of the transformer T1 being connected to the input circuit of the charger. The input circuit is used for inputting alternating current as a charging power supply and receiving the electric signal of the output circuit according to the feedback circuit so as to adjust the electric signal on the primary winding side. The transformer T1 also includes a secondary winding and an auxiliary winding. Fig. 3 is a circuit diagram of an embodiment of the utility model. Referring to fig. 3, the two ends of the secondary winding are connected to a first rectifying and voltage stabilizing circuit. And two ends of the auxiliary winding are connected with a second rectifying and voltage stabilizing circuit. The rectification and voltage regulation circuits each comprise a diode device for rectification and an RC circuit for voltage regulation and surge prevention.
The output circuit includes a relay circuit. The relay circuit includes a relay coil K and a relay switch K1.
The first transistor Q1 in the embodiment is NPN type. The first end of the relay coil K is connected with the collector of the first triode Q1, and the emitter of the first triode Q1 is connected with the reference ground terminal. The base of the first transistor Q1 is connected to the first output terminal of the control chip IC2 through a first resistor R1. Two ends of the second resistor R2 are respectively connected to the base and the emitter of the first triode Q1. The second terminal of the relay coil K is connected to the +12V voltage through a third resistor R3. The first end of the relay switch K1 is connected to the output end of the second rectifying and voltage stabilizing circuit, and the second end of the relay switch K2 is used as the anode output end of the output circuit of the lithium battery charger.
The MOS transistor Q2 in the embodiment is of an N-channel type, the drain of the MOS transistor Q2 is connected to the first end of the relay switch K1, and the source of the MOS transistor Q2 is connected to the second end of the relay switch K1 through a fourth resistor R4 and a second diode D2. That is, when the relay switch K1 is closed, the source and drain of the MOS transistor Q2 are disconnected. The gate of the MOS transistor Q2 is connected to the output of the MOS transistor control circuit.
The MOS tube control circuit comprises an optical coupler U1. The optical coupler U1 includes an input end and an output end. In an embodiment, the first input end of the optocoupler U1 is an anode end of the light emitting diode, the second input end is a cathode end of the light emitting diode, the first output end is a collector electrode of the receiving tube, and the second output end is an emitter electrode of the receiving tube. And a second output end of the optical coupler U1 is used as an output end of the MOS tube control circuit and is connected with the grid electrode of the MOS tube Q1. A first output end of the optocoupler U1 is connected with an output end of the second rectifying and voltage stabilizing circuit. A first input end of the optocoupler U1 is connected to a second output end of the control chip IC2 through a fifth resistor R5 and a sixth resistor R6. The second input end of the optocoupler U1 is connected with the collector of the second triode Q3, the emitter of the second triode Q3 is grounded, and the base of the second triode Q3 is connected with the output end of the voltage division circuit. The second transistor Q3 in the embodiment is NPN type.
The voltage division circuit includes a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9. The seventh resistor R7 and the eighth resistor R8 are connected in series, one end of the seventh resistor R7 in the series circuit is connected to the positive output terminal of the lithium battery charger, and one end of the eighth resistor R8 is connected to the reference ground terminal. The first end of the ninth resistor R9 is connected to the common end of the seventh resistor R7 and the eighth resistor R8, and the second end of the ninth resistor R9 is connected to the base of the second transistor Q3 as the output end of the voltage divider circuit.
The sampling circuit includes an amplifier chip IC1, and an operational amplifier is built in the amplifier chip IC 1. The negative electrode output end of the lithium battery charger is connected to the non-inverting input end of the IC1 of the amplifying chip through a tenth resistor R10. The inverting input terminal of the amplifier chip IC1 is connected to the reference ground terminal through an eleventh resistor R11, the inverting input terminal of the amplifier chip IC1 is connected to the output terminal of the amplifier chip IC1 through a twelfth resistor R12, and the output terminal of the amplifier chip IC1 is connected to the input terminal of the control chip IC2 through a thirteenth resistor R13.
The input end of the control chip IC receives the signal output by the sampling circuit, the control signal is output from the first output end to control the conduction or the disconnection of the relay coil, and the control signal is output from the second output end to control the conduction or the disconnection of the MOS tube Q2.
The working method of the utility model is that when the output circuit of the lithium battery charger is in no-load, the sampling circuit feeds back the no-load and no-current condition to the input end of the control chip IC2 by monitoring the output circuit, the first output end of the control chip IC2 does not output signals, the first triode Q1 is cut off, the relay coil K is not electrified, and the relay switch K1 is opened. The second output end of the control chip IC2 outputs a pulse signal, and the optocoupler U1 is also turned on and off corresponding to the pulse signal to control the MOS transistor Q2 to be turned on or off, and then the output circuit of the lithium battery charger also outputs the pulse signal.
When the output circuit of lithium electricity charger connects the battery, and the battery is when connecing, sampling circuit is through monitoring output circuit, and the condition feedback that will have the electric current is to control chip IC 2's input, and control chip IC 2's first output high level, and first triode Q1 switches on, and relay coil K circular telegram, relay switch K1 is closed, opens circuit MOS pipe Q2, and the output circuit of lithium electricity charger is for the battery normally charges.
When the output circuit of lithium electricity charger connects the battery, and the battery is when connecing conversely, sampling circuit passes through monitoring output circuit, will have the condition feedback of electric current to control chip IC 2's input, and control chip IC 2's first output is output signal not, and first triode Q1 ends, and relay coil K does not circular telegram, and relay switch K1 is opened. The seventh resistor R7, the eighth resistor R8 and the ninth resistor R9 of the voltage division circuit transmit the negative voltage to the base electrode of the second triode Q3, the second triode Q3 is cut off, the input end of the optical coupler U1 is not conducted, the grid electrode of the MOS tube Q2 has no voltage, and the MOS tube Q2 is cut off. Since the relay switch K1 is turned on and the MOS transistor Q2 is turned off at this time, the battery discharge circuit is open, and a protection effect is provided.
Other circuit configurations of the lithium battery charger, such as the input circuit, etc., to which the present invention relates, may be implemented using existing technologies, and the present invention does not relate to improvements thereto.
The foregoing description is illustrative of the present invention and is not to be construed as limiting the utility model, which is defined by the scope of the appended claims, as the utility model may be modified in any manner without departing from the essential structure thereof.
Claims (10)
1. A lithium battery charger output switch circuit with a reverse connection protection function comprises a transformer; the transformer includes a secondary winding; the secondary winding is connected with an output circuit, and the output circuit further comprises a relay circuit, an MOS tube, a sampling circuit and an MOS tube control circuit; the relay circuit comprises a relay switch; the first end of the relay switch is connected to the secondary winding, and the second end of the relay switch is used as the positive output end of the output circuit; the first pole and the second pole of the MOS tube are connected in parallel with two ends of the relay switch; the input end of the sampling circuit is connected with the output end of the output circuit; the output end of the sampling circuit inputs signals to the control chip; the first output end of the control chip controls the on or off of the relay switch; the second output end of the control chip is connected to the input end of the MOS tube control circuit, and the output end of the MOS tube control circuit is connected with the grid electrode of the MOS tube.
2. A lithium battery charger output switch circuit with reverse connection protection function as claimed in claim 1, wherein said relay circuit further comprises a relay coil, a first end of the relay coil is connected to a collector of the first triode, and an emitter of the first triode is connected to a reference ground terminal; the base electrode of the first triode is connected to the first output end of the control chip through a first resistor; the second end of the relay coil is connected to the operating voltage through a third resistor.
3. A lithium battery charger output switch circuit with reverse-connect protection as claimed in claim 1 further comprising an auxiliary winding; the MOS tube control circuit comprises an optical coupler; a second output end of the optical coupler is used as an output end of the MOS tube control circuit and is connected with a grid electrode of the MOS tube; the first output end of the optical coupler is connected with the output end of the auxiliary winding; a first input end of the optocoupler is connected to a second output end of the control chip; the second input end of the optocoupler is connected with the collector of the second triode, the emitter of the second triode is grounded, and the base of the second triode is connected with the output end of the output circuit.
4. A lithium battery charger output switch circuit with a reverse connection protection function as claimed in claim 3, wherein the MOS tube control circuit further comprises a voltage division circuit, and the base of the second triode is connected with the output end of the voltage division circuit; the input end of the voltage division circuit is connected with the output end of the output circuit.
5. A lithium-ion battery charger output switch circuit with a reverse connection protection function as claimed in claim 3, characterized in that a second rectifying and voltage stabilizing circuit is further connected between the auxiliary winding and the optocoupler.
6. A lithium battery charger output switch circuit with reverse-connection protection function as claimed in claim 1, wherein the sampling circuit comprises an operational amplifier; the output end of the output circuit is connected to the non-inverting input end of the operational amplifier through a tenth resistor; the inverting input end of the operational amplifier is connected to the reference ground end through an eleventh resistor, the inverting input end of the operational amplifier is connected to the output end of the operational amplifier through a twelfth resistor, and the output end of the operational amplifier is connected to the input end of the control chip through a thirteenth resistor.
7. A lithium battery charger output switch circuit with reverse connection protection function as claimed in claim 1, wherein said sampling circuit comprises an amplifying chip; the model of the amplifying chip is LM 358; the output end of the output circuit is connected to the non-inverting input end of the amplifying chip through a tenth resistor; the inverting input end of the amplifying chip is connected to the reference ground end through an eleventh resistor, the inverting input end of the amplifying chip is connected to the output end of the amplifying chip through a twelfth resistor, and the output end of the amplifying chip is connected to the input end of the control chip through a thirteenth resistor.
8. A lithium battery charger output switch circuit with reverse connection protection function as claimed in claim 1, characterized in that the model of said control chip is OB39R08A 3.
9. A lithium battery charger output switch circuit with reverse connection protection function as claimed in claim 1, characterized in that a first rectifying and voltage stabilizing circuit is connected between the secondary winding of the transformer and the output circuit.
10. A lithium battery charger, comprising a transformer; the primary winding end of the transformer is connected with a charging power supply through an input circuit; the secondary side of the transformer comprises a secondary winding and an auxiliary winding; mounting an output circuit as claimed in any one of claims 1 to 9 on a secondary side of a transformer; the output end of the output circuit is connected with the battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122329004.2U CN215646324U (en) | 2021-09-24 | 2021-09-24 | Lithium battery charger output switch circuit with reverse connection protection function and charger |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122329004.2U CN215646324U (en) | 2021-09-24 | 2021-09-24 | Lithium battery charger output switch circuit with reverse connection protection function and charger |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN215646324U true CN215646324U (en) | 2022-01-25 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122329004.2U Active CN215646324U (en) | 2021-09-24 | 2021-09-24 | Lithium battery charger output switch circuit with reverse connection protection function and charger |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN215646324U (en) |
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2021
- 2021-09-24 CN CN202122329004.2U patent/CN215646324U/en active Active
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