High-voltage-resistant buffer circuit and charger

Abstract

The utility model discloses a high-voltage-withstanding buffer circuit and a charger. The high-voltage-withstanding buffer circuit comprises a voltage detection module, an MCU and a buffer module. The voltage detection module is provided with a first input end, a second input end and an output end; the first input end of the voltage detection module is connected with the NV1 end, and the second input end of the voltage detection module is connected with the LV1 end; the output end of the voltage detection module is connected with the buffer module; the MCU is electrically connected with the voltage detection module and the buffer module. The buffer module comprises a first input end and a second input end, the first input end of the buffer module is connected with the NV1 end, and the second end of the buffer module is connected with the LV1 end.

Description

Technical Field

[0001] The utility model relates to the technical field of buffer circuits, and specifically, to a high-voltage-resistant buffer circuit and a charger. Background Art

[0002] In the circuit structure of a charger, a filter capacitor is usually used to filter out the AC components contained in the direct current, as Figure 1 shown. Figure 1 As shown in the figure, for the circuit structure of an existing charger, in the existing charger structure, the mains input is rectified by a rectifier bridge stack, which converts the alternating current into direct current, and then the direct current is filtered by a capacitor C1 and then output to the subsequent circuit. However, there are 220V single-phase power and 380V three-phase power in the current market power grid, and the 220V single-phase power is basically branched from the 380V three-phase power. In the wiring method of trailing wires, it is easy to connect the neutral wire of the 220V single-phase power to the 380V three-phase power. When the wiring is incorrect, since the charger is directly connected to the mains, the 380V three-phase voltage is directly input into the rectifier bridge stack of the charger circuit. At this time, the 380V three-phase voltage is too high, and there is a risk of burning out the rectifier bridge stack. Moreover, the voltage value output after the 380V three-phase voltage is rectified by the rectifier bridge stack reaches as high as 537V, while the withstand voltage value of the capacitor C1 is only 450V, which causes the capacitor C1 to be damaged by the excessive voltage, thus resulting in the damage of the charger. Content of the Utility Model

[0003] Aiming at the deficiencies of the prior art, a high-voltage-resistant buffer circuit and a charger are provided.

[0004] To achieve the above object, the utility model provides a high-voltage-resistant buffer circuit, which includes a voltage detection module, an MCU and a buffer module; the voltage detection module has a first input terminal, a second input terminal and an output terminal; the first input terminal of the voltage detection module is connected to the NV1 terminal, and the second input terminal of the voltage detection module is connected to the LV1 terminal; the output terminal of the voltage detection module is connected to the buffer module; the MCU is electrically connected to the voltage detection module and the buffer module respectively; the first input terminal and the second input terminal of the buffer module, the first input terminal of the buffer module is connected to the NV1 terminal, and the second terminal of the buffer module is connected to the LV1 terminal.

[0005] According to an embodiment of the utility model, the voltage detection module includes a voltage comparator U1, a first filtering unit, a negative feedback unit and a second filtering unit. The positive input terminal of the voltage comparator U1 is connected to the NV1 terminal, the negative input terminal of the voltage comparator U1 is connected to the LV1 terminal, and the output terminal of the voltage comparator U1 is connected to the MCU; the negative feedback unit is connected between the negative input terminal and the output terminal of the voltage comparator U1; the first filtering unit is connected to the positive input terminal of the voltage comparator U1; one end of the second filtering unit is connected to the output terminal of the voltage comparator U1, and the other end is connected to the MCU.

[0006] According to an embodiment of the present utility model, the voltage detection module further includes a voltage dividing module, and the voltage dividing module includes a first voltage dividing unit and a second voltage dividing unit; one end of the first voltage dividing unit is connected to the NV1 terminal, and the other end thereof is connected to the positive input terminal of the voltage comparator U1; one end of the second voltage dividing unit is connected to the LV1 terminal, and the other end thereof is connected to the negative input terminal of the voltage comparator U1.

[0007] According to an embodiment of the present utility model, the buffer module includes a third voltage dividing unit, a switching unit and a third filtering unit; one end of the third voltage dividing unit is connected to the NV1 terminal, and the other end thereof is connected to one end of the second filtering unit; the switching unit is connected in parallel with the third voltage dividing unit; the other end of the third filtering unit is connected to the LV1 terminal; the switching unit is electrically connected to the MCU.

[0008] According to an embodiment of the present utility model, the first filtering unit includes a first filtering component and a first current limiting component. One end of the first filtering component is respectively connected to the NV1 terminal and the positive input terminal of the voltage amplifier, and the other end thereof is connected to the operating voltage; the first current limiting component is connected in parallel with the first filtering component.

[0009] According to an embodiment of the present utility model, the negative feedback unit includes a second filtering component and a second current limiting component. One end of the second filtering component is connected to the negative input terminal of the voltage comparator U1, and the other end thereof is connected to the output terminal of the voltage comparator U1; the second current limiting component is connected in parallel across both ends of the second filtering component.

[0010] According to an embodiment of the present utility model, the second filtering unit includes a third current limiting component and a third filtering component. One end of the third current limiting component is respectively connected to the negative feedback unit and the output terminal of the voltage comparator U1, and the other end thereof is connected to the MCU. One end of the third filtering component is respectively connected to the third current limiting component and the MCU, and the other end thereof is grounded.

[0011] According to an embodiment of the present utility model, the voltage detection module further includes an anti-interference unit. One end of the anti-interference unit is connected to the negative input terminal of the voltage comparator U1, and the other end thereof is connected to the positive input terminal of the voltage comparator U1.

[0012] According to an embodiment of the present utility model, it further includes a rectifier bridge stack and an energy storage module. The input terminal of the rectifier bridge stack is connected to the output terminal of the buffer module, and the output terminal of the rectifier bridge stack is connected to the energy storage module.

[0013] The present utility model also provides a charger, which includes the above-mentioned high-voltage withstand buffer circuit.

[0014] The beneficial effects of the present utility model are as follows: By setting a buffer circuit before the rectifier bridge stack, when the wiring is connected wrongly and an excessive voltage is generated, the MCU controls the buffer module to open, so that the voltage signal is divided by the buffer module. In this way, it effectively avoids the components from being burned out due to excessive input voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0016] Figure 1 is the circuit structure of the existing charger;

[0017] Figure 2 is a schematic diagram of the high-voltage-resistant buffer circuit in the embodiment;

[0018] Figure 3 is the circuit diagram of the voltage detection module in the embodiment;

[0019] Figure 4 is the connection schematic diagram of the voltage division module and the voltage detection module in the embodiment.

[0020] Explanation of Reference Numerals

[0021] 1 - Voltage detection module; 11 - First filtering unit; 111 - First filtering component; 112 - First current-limiting component; 12 - Negative feedback unit; 121 - First filtering component; 122 - First current-limiting component; 13 - Second filtering unit; 131 - Third current-limiting component; 132 - Third filtering component; 14 - Voltage division module; 141 - First voltage division unit; 142 - Second voltage division unit; 15 - Anti-interference unit; 2 - MCU; 3 - Buffer module; 31 - Third voltage division unit; 32 - Switch unit; 33 - Third filtering unit; 4 - Rectifier bridge stack; 5 - Energy storage module. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The following will disclose multiple embodiments of the present utility model in the form of diagrams. For the sake of clarity, many practical details will be described together in the following narrative. However, it should be understood that these practical details are not used to limit the present utility model. That is to say, in some embodiments of the present utility model, these practical details are not necessary. In addition, for the purpose of simplifying the diagrams, some well-known and commonly used structures and components will be shown in a simple schematic manner in the diagrams.

[0023] In addition, in the present utility model, descriptions such as "first", "second", etc. are only for descriptive purposes, and do not particularly refer to the meaning of order or sequence, nor are they used to limit the present utility model. They are merely used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0024] Please refer to Figure 2 as shown in Figure 2 a schematic diagram of the high-voltage withstand buffer circuit in this embodiment. This embodiment provides a high-voltage withstand buffer circuit, which includes a voltage detection module 1, an MCU 2, and a buffer module 3. The voltage detection module 1 has a first input terminal, a second input terminal, and an output terminal. The first input terminal and the second input terminal of the voltage detection module 1 are connected to the mains power supply. Specifically, the first input terminal of the voltage detection module 1 is connected to the NV1 terminal of the mains power supply, and the second input terminal of the voltage detection module 1 is connected to the LV1 terminal of the mains power supply. The output terminal of the voltage detection module 1 is connected to the MCU 2. The MCU 2 is also electrically connected to the buffer module 3, and the MCU 2 controls the usage state of the buffer module 3. The buffer module 3 has a first input terminal, a second input terminal, and an output terminal. The first input terminal of the buffer module 3 is connected to the NV1 terminal, and its second input terminal is connected to the LV2 terminal. The buffer module 3 receives the mains power supply, changes its state according to the control of the MCU 2, divides the voltage of the mains power supply, and then inputs it into the subsequent circuit to avoid damage to the circuit caused by large voltages.

[0025] During the actual use process, the output terminal of the buffer module 3 is connected to a rectifier bridge 4, and the rectifier bridge 4 is connected to an energy storage module 5. The voltage detection module 1 receives the input mains power supply, samples the mains power supply and generates a sampling signal, and then the sampling signal is input into the MCU 2. The MCU 2 compares the sampling signal with a reference value and judges whether there is a wiring error in the power supply by comparing the magnitudes of the sampling signal and the reference value. When the sampling signal is less than the reference value, it is judged that the wiring is correct; when the sampling signal is greater than or equal to the reference value, it is judged that the wiring is incorrect. When the power supply is not miswired, the MCU 2 controls the buffer module 3 to be turned off, and the circuit operates normally; when the power supply is miswired, the MCU 2 controls the buffer module 3 to be turned on, so that the current passes through the buffer module 3 to step down the voltage, and then charges the energy storage module 5 through the rectifier bridge 4, thereby avoiding damage to the circuit caused by excessive voltage when the wiring is incorrect.

[0026] Please refer to Figure 3 , Figure 3It is the circuit diagram of the voltage detection module. Specifically, the voltage detection module 1 includes a voltage comparator U1, a negative feedback unit 12, a first filtering unit 11, and a second filtering unit 13. The voltage comparator U1 has a positive input terminal, a negative input terminal, and an output terminal. Among them, the positive input terminal of the voltage comparator U1 is connected to the NV1 terminal, the negative input terminal of the voltage comparator U1 is connected to the LV1 terminal, and the output terminal of the voltage comparator U1 is connected to the MCU2. One end of the first filtering unit 11 is connected to the NV1 terminal, and the other end is connected to the positive input terminal of the voltage comparator U1. The first filtering unit 11 is used to filter the input voltage signal. The negative feedback unit 12 is connected between the negative input terminal and the output terminal of the voltage comparator U1, and it is used for the negative feedback of the voltage comparator U1 to reduce the output error of the voltage comparator U1 and make the voltage detection module 1 tend to be stable. One end of the second filtering unit 13 is respectively connected to the negative feedback unit 12 and the output terminal of the voltage comparator U1, and the other end is connected to the MCU2. The second filtering unit 13 is used to perform low-pass filtering on the output signal of the voltage comparator U1. It should be noted that in this example, the NV1 terminal is connected to the live wire of the single-phase power supply, and the LV1 terminal is connected to the neutral wire of the single-phase power supply. The MCU2 uses the STM32F446 chip.

[0027] Furthermore, the first filtering unit 11 includes a first filtering component 111 and a first current limiting component 112. One end of the first filtering component 111 is respectively connected to the NV1 terminal and the positive input terminal of the voltage amplifier, and the other end is connected to the operating voltage. The first current limiting component 112 is connected in parallel across the two ends of the first filtering component 111. In this example, the first filtering component 111 is the capacitor C73, and the first current limiting component 112 is the resistor R139. Among them, the capacitor C73 is a power supply decoupling filtering capacitor, and the resistor R139 is used for current limiting.

[0028] The negative feedback unit 12 includes a second filtering component 121 and a second current limiting component 122. One end of the second filtering component 121 is connected to the negative input terminal of the voltage comparator U1, and the other end is connected to the output terminal of the voltage comparator U1. The second filtering component 121 is used for filtering. The second current limiting component 122 is connected in parallel across the two ends of the second filtering component 121, and it is used for current limiting and voltage division. In this example, the second filtering component 121 is the capacitor C65, and the second current limiting component 122 is the resistor R129.

[0029] The second filtering unit 13 includes a third current limiting component 131 and a third filtering component 132. One end of the third current limiting component 131 is respectively connected to the negative feedback unit 12 and the output terminal of the voltage comparator U1, and the other end is connected to the MCU2, so that the output signal of the voltage comparator U1 passes through the third current limiting component 131 and the third filtering component 132 to filter out high-frequency signals and then output to the MCU2. In this example, the third current limiting component 131 is the resistor R134, and the third filtering component 132 is C72. The resistor R134 is used for current limiting, and the capacitor C72 is used for filtering.

[0030] Please refer to Figure 4 , Figure 4 which is a schematic diagram of the connection between the voltage dividing module and the voltage detection module. In addition, the voltage detection module 1 further includes a voltage dividing module 14. The voltage dividing module 14 includes a first voltage dividing unit 141 and a second voltage dividing unit 142. Among them, one end of the first voltage dividing unit 141 is connected to the LV1 terminal, and the other end is connected to the inverting input terminal of the voltage comparator U1. One end of the second voltage dividing unit 142 is connected to the NV1 terminal, and the other end is connected to the non-inverting input terminal of the voltage comparator U1. In this example, the first voltage dividing unit 141 is the resistor R132, and the second voltage dividing unit 142 is the resistor R137. The resistor R132 divides the voltage for the inverting input terminal of the voltage comparator U1, and the resistor R137 divides the voltage for the non-inverting input terminal of the voltage comparator U1, avoiding excessive current from directly entering the voltage comparator U1 and preventing the voltage comparator U1 from being damaged.

[0031] The voltage detection module 1 further includes an anti-interference unit 15. One end of the anti-interference unit 15 is connected to the inverting input terminal of the voltage comparator U1, and the other end is connected to the non-inverting input terminal of the voltage comparator U1. The anti-interference unit 15 is used for anti-interference. When the input voltage undergoes a sudden change, the anti-interference unit 15 can filter the voltage that changes instantaneously. In this example, the anti-interference unit 15 is the capacitor C69.

[0032] The buffer module 3 includes a third voltage dividing unit 31, a switch unit 32, and a third filtering unit 33. One end of the third voltage dividing unit 31 is connected to the NV1 terminal, and the other end is connected to one end of the third filtering unit 33. The switch unit 32 is connected in parallel with the third voltage dividing unit 31. The other end of the third filtering unit 33 is connected to the LV1 terminal. The switch unit 32 is electrically connected to the MCU2 and is controlled by the MCU2.

[0033] When the MCU2 detects that the sampling signal is greater than the reference value, the MCU2 controls the switch unit 32 to open, so that the third voltage dividing unit 31 and the third filtering unit 33 are connected in series with each other. The input voltage flows through the third voltage dividing unit 31 and the third filtering unit 33 in sequence. At this time, the third voltage dividing unit 31 and the third filtering unit 33 divide the voltage, so that the input voltage is reduced to a reasonable range, thereby achieving the purpose of buffering and effectively avoiding excessive voltage from damaging the circuit components.

[0034] In this example, the third voltage dividing unit 31 is the capacitor C2, the switch unit 32 is the relay K1, and the third filtering unit 33 is the capacitor C3. When the relay K1 is open, the capacitor C2 and the capacitor C3 are connected in series with each other. Due to the characteristics of the capacitor itself, when two capacitors are connected in series, the withstand voltage value of the capacitor doubles. Therefore, by controlling the switch state of the relay K1, the withstand voltage value of the capacitor C2 and the capacitor C3 is enhanced, thereby achieving the effect of voltage division and buffering for high voltage.

[0035] The high-voltage withstand buffer circuit in this embodiment further includes a rectifier bridge 4 and an energy storage module 5. The input end of the rectifier bridge 4 is connected to the output end of the buffer module 3, and the output end of the rectifier bridge 4 is connected to the energy storage module 5.

[0036] In an actual application scenario, the voltage of the mains power supply is input to the voltage detection module 1. The voltage detection module 1 divides and samples the input voltage for calculation, and then outputs a sampling signal to the MCU 2. The MCU 2 receives the sampling signal and compares the sampling signal with a reference current value. If the sampling signal value is less than the reference current value, the MCU 2 does not trigger the switch unit 32. At this time, the output voltage of the mains power supply at the NV1 end sequentially passes through the switch unit 32 and the third filtering unit 33. The third filtering unit 33 filters the voltage of the input mains power supply, and then returns to the LV1 end of the mains power supply. At the same time, the voltage of the mains power supply charges the third filtering unit 33. After the third filtering unit 33 finishes charging, it discharges. The discharge current of the third filtering unit 33 is rectified by the rectifier bridge 4, so that the input alternating current is converted into direct current to charge the energy storage module 5.

[0037] If the sampling signal value is greater than or equal to the reference current value, the MCU 2 triggers the switch unit 32, so that the third voltage dividing unit 31 is connected in series with the third filtering unit 33, and the voltage withstand values of the third voltage dividing unit 31 and the third filtering unit 33 are increased. At this time, the output voltage of the mains power supply at the NV1 end sequentially passes through the third voltage dividing unit 31 and the third filtering unit 33, and the third voltage dividing unit 31 and the third filtering module divide the voltage. After voltage division, the input voltage decreases, avoiding overvoltage directly inputting to the rectifier bridge 4 and damaging the circuit. The alternating current after voltage division is rectified by the rectifier bridge 4 and then becomes direct current output, and then charges the energy storage module 5.

[0038] The present utility model also provides a charger, including the above-mentioned high-voltage withstand buffer circuit.

[0039] In summary, by setting a buffer circuit before the rectifier bridge, when the wiring is connected wrongly and an excessive voltage is generated, the MCU 2 controls the buffer module 3 to open, so that the voltage signal is divided by the buffer module 3. In this way, it effectively avoids the components from being burned out due to excessive input voltage.

[0040] The above are only embodiments of the present utility model and are not used to limit the present utility model. For those skilled in the art, the present utility model can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the scope of the claims of the present utility model.

Claims

1. A high withstand voltage buffer circuit, characterized in that: include: A voltage detection module (1), an MCU (2) and a buffer module (3); the voltage detection module (1) has a first input end, a second input end and an output end; the first input end of the voltage detection module (1) is connected to the NV1 end, and the second input end of the voltage detection module (1) is connected to the LV1 end; the output end of the voltage detection module (1) is connected to the buffer module (3); the MCU (2) is electrically connected to the voltage detection module (1) and the buffer module (3) respectively; the first input end and the second input end of the buffer module (3), the first input end of the buffer module is connected to the NV1 end, and the second end of the buffer module is connected to the LV1 end.

2. The high withstand voltage buffer circuit according to claim 1, characterized in that: The voltage detection module (1) comprises a voltage comparator U1, a first filtering unit (11), a negative feedback unit (12) and a second filtering unit (13); the positive input end of the voltage comparator U1 is connected to the NV1 end, the negative input end of the voltage comparator U1 is connected to the LV1 end, and the output end of the voltage comparator U1 is connected to the MCU (2); the negative feedback unit (12) is connected between the negative input end and the output end of the voltage comparator U1; the first filtering unit (11) is connected to the positive input end of the voltage comparator U1; one end of the second filtering unit (13) is connected to the output end of the voltage comparator U1, and the other end thereof is connected to the MCU (2).

3. The high withstand voltage buffer circuit according to claim 2, characterized in that: The voltage detection module (1) further comprises a voltage dividing module (14), wherein the voltage dividing module (14) comprises a first voltage dividing unit (141) and a second voltage dividing unit (142); one end of the first voltage dividing unit (141) is connected to the NV1 end, and the other end thereof is connected to the positive input end of the voltage comparator U1; one end of the second voltage dividing unit (142) is connected to the LV1 end, and the other end thereof is connected to the negative input end of the voltage comparator U1.

4. The high withstand voltage buffer circuit according to claim 1, characterized in that: The buffer module (3) comprises a third voltage dividing unit (31), a switch unit (32) and a third filtering unit (33); one end of the third voltage dividing unit (31) is connected to the NV1 end, and the other end thereof is connected to one end of the third filtering unit (33); the switch unit (32) is connected in parallel with the third voltage dividing unit (31); the other end of the third filtering unit (33) is connected to the LV1 end; and the switch unit (32) is electrically connected to the MCU (2).

5. The high withstand voltage buffer circuit according to claim 2, characterized in that: The first filtering unit (11) comprises a first filtering component (111) and a first current limiting component (112); one end of the first filtering component (111) is respectively connected to the NV1 terminal and the positive input terminal of the voltage amplifier, and the other end of the first filtering component (111) is connected to the operating voltage; the first current limiting component (112) is connected in parallel with the first filtering component (111).

6. The high withstand voltage buffer circuit according to claim 2, characterized in that: The negative feedback unit (12) comprises a second filter element (121) and a second current limiting element (122); one end of the second filter element (121) is connected to the reverse input end of the voltage comparator U1, and the other end of the second filter element (121) is connected to the output end of the voltage comparator U1; the second current limiting element (122) is connected in parallel to both ends of the second filter element (121).

7. The high withstand voltage buffer circuit according to claim 2, characterized in that: The second filtering unit (13) comprises a third current limiting component (131) and a third filtering component (132); one end of the third current limiting component (131) is respectively connected to the negative feedback unit (12) and the output end of the voltage comparator U1, and the other end thereof is connected to the MCU (2); one end of the third filtering component (132) is respectively connected to the third current limiting component (131) and the MCU (2), and the other end thereof is grounded.

8. The high withstand voltage buffer circuit according to claim 2, characterized in that: The voltage detection module (1) further comprises an anti-interference unit (15), one end of the anti-interference unit (15) being connected to the reverse input end of the voltage comparator U1, and the other end of the anti-interference unit (15) being connected to the forward input end of the voltage comparator U1.

9. The high withstand voltage buffer circuit according to claim 1, characterized in that: It also includes a rectifier bridge stack (4) and an energy storage module (5), wherein the input end of the rectifier bridge stack (4) is connected to the output end of the buffer module (3), and the output end of the rectifier bridge stack (4) is connected to the energy storage module (5).

10. A charger, characterized in that: A high withstand voltage buffer circuit comprising any one of claims 1-9.

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