Reverse connection protection circuit for charger
By designing a reverse connection protection circuit including high-voltage isolation circuit, sampling bias circuit, sampling circuit and MCU controller, the battery short circuit problem caused by the reverse connection of the charger output terminal and the battery terminal polarity is solved, and reliable detection and protection of the reverse connection of the battery is achieved, reducing circuit complexity and cost.
Patent Information
- Application Number
- CN202421397158.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-19
- Publication Date
- 2025-04-15
- Estimated Expiration
- 2034-06-19
AI Technical Summary
During charging, the polarity of the output end of the charger is inverted from the polarity of the battery end, which will cause the battery to be short-circuit in the charging circuit and cause damage to the charger or battery.
A reverse protection circuit including a high voltage isolation circuit, a sampling bias circuit, a sampling circuit and an MCU controller are designed. The sampling circuit is equipped with N sampling resistors in series in sequence. The sampling bias circuit provides forward biasing and clamping through the biasing diode and resistor, realizing reverse sampling and protection.
Without negative voltage power supply and negative voltage sampling, reliable detection and protection of battery reverse connection is achieved, avoiding damage to the charger and battery, while reducing the complexity and cost of the circuit.
Smart Images
Figure CN222763597U_ABST
Abstract
Description
Technical field:
[0001] The utility model relates to the technical field of power electronics, in particular to a reverse connection protection circuit for a charger which has a reasonable structure, is easy to operate and is suitable for charger products for new energy electric vehicles. Background technology:
[0002] With the application of new energy technology, more and more batteries are used in our daily life. In particular, new energy electric vehicles are powered by electricity, so the equipment needs a charger to charge in order to operate normally. During the charging process, the charger is connected to a storage device such as a battery or a battery pack, and the battery is charged through a charging circuit. The charger can only work normally when and only when the positive and negative polarity of the charger output terminal matches the positive and negative polarity of the battery terminal. Once the polarity of the charger output terminal is reversed with the polarity of the battery terminal, the battery in the charging circuit will be short-circuited at the moment the charger is turned on, causing damage to the charger or even the battery.
[0003] In order to solve the above problem, the existing technology performs sampling and judgment by setting a negative voltage in the charging circuit. That is, if the polarity of the charger output terminal is reversed with the battery polarity, the MCU inside the charger will sample a negative voltage, and then determine that the battery is reversed, alarm and prompt, and ensure that the charger does not start working. However, the circuit structure in the existing technology is complex and the cost is high. Summary of the invention:
[0004] The utility model solves the shortcomings and deficiencies in the prior art and proposes a reverse connection protection circuit for a charger which has a simple circuit structure, low cost and reliable detection.
[0005] The utility model can be achieved through the following technical solutions:
[0006] A reverse connection protection circuit for a charger comprises a high-voltage isolation circuit, a sampling bias circuit, a sampling circuit, and an MCU controller, wherein the sampling circuit is provided with N sampling resistors connected in series in sequence, N≥2, wherein the first sampling resistor is connected to the positive electrode of a battery to be charged, the Nth sampling resistor is connected to the negative electrode of the battery to be charged, and the voltage division output of the Nth sampling resistor is the sampling voltage; the sampling bias circuit comprises a first bias diode and a first bias resistor, the first bias diode is connected in parallel with the Nth sampling resistor, the anode of the first bias diode is connected to the negative electrode of the rechargeable battery, one end of the first sampling bias resistor is connected to the cathode of the first bias diode, and the other end is connected to a 3.3V power supply.
[0007] The sampling circuit of the utility model is connected in parallel with the high-voltage isolation circuit, one end of the high-voltage isolation circuit is directly connected to the battery to be charged, and the other end is connected to the power conversion main circuit; the high-voltage isolation circuit includes an isolation relay, a charging diode, and a charging resistor, the charging diode is connected in series with the charging resistor and then connected in parallel with the relay, the relay is connected between the battery to be charged and the power conversion main circuit of the charger, the control signal end of the relay is connected to the controller MCU controller, before the normal start output, the relay is in an open circuit state to isolate the current conduction loop during reverse connection; through the application of the charging diode and the charging resistor, the voltage difference between the two ends of the relay contact when the battery is normally connected can be effectively balanced.
[0008] The sampling bias circuit of the utility model provides a forward bias of the sampling voltage when the battery is normally connected; when the battery is reversely connected, the bias diode is turned on, the reverse voltage is clamped, and a clamping value of the reverse sampling voltage is provided.
[0009] The MCU controller of the utility model comprises a plurality of groups of ADC sampling channels, and the output required for sampling enters the ADC sampling circuit after passing through RC low-frequency filtering.
[0010] When the utility model is working, when the charger and the battery are connected in the forward direction, under the action of the sampling bias circuit, through the ADC sampling channel of the MCU, when the battery is zero volt, the MCU controller samples a fixed positive voltage, and this voltage is the sampling bias voltage; when the battery is reversely connected, due to the clamping effect of the bias diode being turned on, the sampling voltage value of the sampling circuit is clamped at a fixed value, and this value is much lower than the sampling bias voltage. Through the implementation of this circuit, in the absence of a negative voltage power supply and negative voltage sampling, the sampling and protection of the battery reverse connection is realized.
[0011] Compared with the prior art, the utility model has the remarkable advantages of reasonable structure, low cost and reliable detection. Description of the drawings:
[0012] Attached Figure 1 It is a structural frame diagram of the utility model.
[0013] Attached Figure 2 It is a circuit schematic diagram of embodiment 1 of the utility model.
[0014] Reference numerals: high voltage isolation circuit 1 , sampling bias circuit 2 , sampling circuit 3 , MCU controller 4 , battery 5 , power conversion main circuit 6 . Specific implementation method:
[0015] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0016] Example:
[0017] As attached Figure 1 As shown, this example provides a reverse connection protection circuit for a charger, including a high-voltage isolation circuit 1, a sampling bias circuit 2, a sampling circuit 3, and an MCU controller 4, wherein the MCU controller 4 is connected to the high-voltage isolation circuit 1 and the sampling bias circuit 2, respectively, the high-voltage isolation circuit 1 and the sampling circuit 3 are connected in parallel, the high-voltage isolation circuit 1 and the sampling circuit 3 are respectively connected to a battery 5 to be charged, and the output end of the sampling circuit 3 is connected to the sampling bias circuit 2;
[0018] Specifically, as attached Figure 2 As shown, in this example, the sampling circuit 3 is provided with N sampling resistors connected in series, N≥2, wherein the first sampling resistor is connected to the positive electrode of the battery to be charged 5, the Nth sampling resistor is connected to the negative electrode of the battery to be charged 5, and the voltage division output of the Nth sampling resistor is the sampling voltage; the sampling bias circuit 2 includes a first bias diode and a first bias resistor, the first bias diode is connected in parallel with the Nth sampling resistor, the anode of the first bias diode is connected to the negative electrode of the rechargeable battery 5, one end of the first sampling bias resistor is connected to the cathode of the first bias diode, and the other end is connected to the 3.3V power supply;
[0019] As attached Figure 2 As shown, the sampling circuit in this example is connected in parallel with the high-voltage isolation circuit 1, one end of the high-voltage isolation circuit 1 is directly connected to the battery to be charged 5, and the other end is connected to the power conversion main circuit 6; the high-voltage isolation circuit 1 includes an isolation relay, a charging diode, and a charging resistor. The charging diode is connected in series with the charging resistor and then connected in parallel with the relay. The relay is connected between the battery to be charged 5 and the power conversion main circuit 6 of the charger. The control signal end of the relay is connected to the controller MCU controller 4. Before the normal start-up output, the relay is in an open circuit state to isolate the current conduction loop during reverse connection; through the application of the charging diode and the charging resistor, the voltage difference across the relay contacts when the battery is normally connected can be effectively balanced.
[0020] The sampling bias circuit 2 described in this example provides a forward bias for the sampling voltage when the battery is normally connected; when the battery is reversely connected, the bias diode is turned on to clamp the reverse voltage and provide a clamping value for the reverse sampling voltage.
[0021] The MCU controller 4 in this example includes multiple groups of ADC sampling channels, and the output required for sampling enters the ADC sampling circuit after passing through RC low-frequency filtering;
[0022] During operation, when the charger and the battery are connected forward, under the action of the sampling bias circuit, through the ADC sampling channel of the MCU, when the battery is zero volts, the MCU samples a fixed positive voltage, which is the sampling bias voltage; when the battery is reversely connected, due to the clamping effect of the bias diode being turned on, the sampling voltage value of the sampling circuit is clamped at a fixed value, which is much lower than the sampling bias voltage. Through the implementation of this circuit, the sampling and protection of the reverse connection of the battery is realized in the absence of a negative voltage power supply and negative voltage sampling.
[0023] Compared with the prior art, the utility model has the remarkable advantages of reasonable structure, low cost and reliable detection.
Claims
1. A reverse connection protection circuit for a charger, comprising a high voltage isolation circuit, a sampling bias circuit, a sampling circuit, and an MCU controller, characterized in that: The sampling circuit is provided with N sampling resistors connected in series in sequence, N≥2, wherein the first sampling resistor is connected to the positive electrode of the battery to be charged, the Nth sampling resistor is connected to the negative electrode of the battery to be charged, and the voltage division output of the Nth sampling resistor is the sampling voltage; the sampling bias circuit includes a first bias diode and a first bias resistor, the first bias diode is connected in parallel with the Nth sampling resistor, the anode of the first bias diode is connected to the negative electrode of the rechargeable battery, one end of the first sampling bias resistor is connected to the cathode of the first bias diode, and the other end is connected to a 3.3V power supply.
2. A reverse connection protection circuit for a charger according to claim 1, characterized in that: The sampling circuit is connected in parallel with the high-voltage isolation circuit, one end of the high-voltage isolation circuit is directly connected to the battery to be charged, and the other end is connected to the power conversion main circuit; the high-voltage isolation circuit includes an isolation relay, a charging diode, and a charging resistor. The charging diode is connected in series with the charging resistor and then connected in parallel with the relay. The relay is connected between the battery to be charged and the power conversion main circuit of the charger. The control signal end of the relay is connected to the controller MCU controller. Before the normal start-up output, the relay is in an open circuit state to isolate the current conduction loop during reverse connection.
3. A reverse connection protection circuit for a charger according to claim 1, characterized in that: The sampling bias circuit provides a forward bias of the sampling voltage when the battery is normally connected; when the battery is reversely connected, the bias diode is turned on, clamping the reverse voltage and providing a clamping value of the reverse sampling voltage.
4. A reverse connection protection circuit for a charger according to claim 1, characterized in that: The MCU controller includes multiple groups of ADC sampling channels, and the output required for sampling enters the ADC sampling circuit after passing through RC low-frequency filtering.