Surge lightning stroke overvoltage protection system and control method thereof

Abstract

The invention discloses a surge lightning stroke overvoltage protection system and a control method thereof. The surge lightning stroke overvoltage protection system comprises a controller, and a second pin of the controller is electrically connected with one end of a sampling resistor, a base electrode of a second triode and a source electrode of a first MOS tube; a third pin of the controller is electrically connected with a collector electrode of a second triode, a collector electrode of a third triode and a grid electrode of a first MOS tube; a first pin of the controller is electrically connected with the emitter of the second triode, the emitter of the third triode and the other end of the sampling resistor and is grounded; the base of the third triode is electrically connected with the emitter of the fourth triode; the collector electrode of the fourth triode is electrically connected with the fifth pin of the controller, the base electrode of the fourth triode is electrically connected with one end of the divider resistor, and the other end of the divider resistor is electrically connected with the fourth pin of the controller and the drain electrode of the first MOS tube. According to the invention, the structure is simple, the occupied space is small, the design difficulty and cost of power electronic products are reduced, and social resources are saved.

Description

Technical Field

[0001] The present invention relates to electrical fields such as charging cabinets, battery exchange cabinets, charging piles, outdoor integrated power supplies, and more particularly to a surge lightning overvoltage protection system and a control method thereof. Background Art

[0002] The surge and lightning overvoltage protection systems currently on the market generally adopt the following methods: 1. A separate lightning arrester, 2. A separate surge protector, 3. A separate overvoltage protection circuit.

[0003] But it has the following disadvantages: 1. A separate lightning arrester, a separate surge protector, and a separate overvoltage protection circuit are divided into three circuit modules, which is very expensive; 2. A separate lightning arrester, a separate surge protector, and a separate overvoltage protection circuit are divided into three circuit modules, which occupy a large volume.

[0004] 3. The varistor used in traditional lightning arresters has a large voltage clamping error.

[0005] 4. Traditional surge protection uses resistors and relays, which require a separate VCC power supply and are more expensive. Summary of the invention

[0006] The object of the present invention is to provide a surge lightning overvoltage protection system.

[0007] To solve the above problems, the technical solution of the present invention is: A surge lightning overvoltage protection system comprises a controller, wherein a second pin of the controller is electrically connected to one end of a sampling resistor, a base of a second triode and a source of a first MOS tube; a third pin of the controller is electrically connected to a collector of the second triode, a collector of a third triode and a gate of the first MOS tube; a first pin of the controller is electrically connected to an emitter of the second triode, an emitter of the third triode and the other end of the sampling resistor and is grounded; a base of the third triode is electrically connected to an emitter of a fourth triode; a collector of the fourth triode is electrically connected to a fifth pin of the controller, a base of the fourth triode is electrically connected to one end of a voltage-dividing resistor, and the other end of the voltage-dividing resistor is electrically connected to a fourth pin of the controller and a drain of the first MOS tube.

[0008] As a further improvement, the first pin of the controller is electrically connected to the positive electrode of the voltage regulator tube Z, and the third pin of the controller is electrically connected to the negative electrode of the voltage regulator tube Z.

[0009] A further improvement is that the base of the third transistor is electrically connected to one end of the fifteenth resistor and one end of the sixteenth resistor, the other end of the fifteenth resistor is electrically connected to the emitter of the fourth transistor, and the other end of the sixteenth resistor is electrically connected to the emitter of the third transistor, the emitter of the second transistor and the first pin of the controller.

[0010] As a further improvement, the third pin of the controller is also electrically connected to one end of the tenth resistor and one end of the eleventh resistor; the other end of the tenth resistor and the other end of the eleventh resistor are electrically connected to the fourth pin of the controller.

[0011] As a further improvement, the third pin of the controller is also electrically connected to one end of a twelfth resistor and one end of a thirteenth resistor; the other end of the twelfth resistor and the other end of the thirteenth resistor are both electrically connected to the fifth pin of the controller.

[0012] As a further improvement, the fifth pin of the controller is electrically connected to one end of a seventeenth resistor, and the other end of the seventeenth resistor is electrically connected to the base of the fourth transistor.

[0013] As a further improvement, the fourth pin of the controller is electrically connected to the drain of the first MOS tube through a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor connected in series in sequence; the fifth pin of the controller is electrically connected to the high-voltage input end through a fifth resistor, a fourth resistor, a third resistor and a second resistor connected in series in sequence; the sum of the resistance values ​​of the sixth resistor, the seventh resistor, the eighth resistor and the ninth resistor is equal to the sum of the resistance values ​​of the fifth resistor, the fourth resistor, the third resistor and the second resistor.

[0014] For further improvement, the designed output voltage is , then:

[0015] The current flowing through the voltage divider resistor is just enough to make the third transistor and the fourth transistor conduct; is the sum of the resistance values ​​of the fifth resistor, the fourth resistor, the third resistor and the second resistor; is the resistance value of the voltage divider resistor; is the resistance value of the twelfth resistor and the thirteenth resistor connected in parallel, and the resistance value of the twelfth resistor and the thirteenth resistor connected in parallel is equal to the resistance value of the tenth resistor and the eleventh resistor connected in parallel; is the BE voltage drop of the fourth transistor.

[0016] A control method for a surge lightning overvoltage protection system, the surge lightning overvoltage protection system as described above, comprises the following steps: Step 1: When the input voltage VH-GND is within the normal range, the voltage across the voltage-dividing resistor is lower than the first preset value, the fourth transistor does not work, and the first MOS tube is normally turned on; Step 2: When the input voltage VH-GND is higher than the preset voltage, the voltage across the voltage-dividing resistor is greater than or equal to the first preset value, the fourth transistor is turned on, and the fourth transistor turns on to cause the third transistor to turn on, thereby lowering the driving voltage of the first MOS tube, making the impedance of the first MOS tube larger, and dividing the excess voltage on the first MOS tube, thereby keeping the target voltage VH-VL unchanged; Step three, the sampling resistor performs current sampling. When the current reaches the second preset value, the second transistor is turned on, the driving voltage of the first MOS tube is lowered, and the impedance of the first MOS tube is increased until the driving voltage of the first MOS tube divided by the impedance is equal to the designed current, thereby achieving current limiting.

[0017] Advantages of the present invention: 1. Contains current sampling reference. When the current flowing exceeds the reference, the impedance of MOS is increased to limit the current; 2. With voltage detection, when the voltage is overvoltage, the MOS tube is used to divide the voltage to protect the subsequent circuit; 3. When lightning strikes high voltage, the bus voltage can be clamped by voltage division; 4. The structure is simple and occupies little space, which reduces the design difficulty and cost of power electronic products and saves social resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall circuit structure of the present invention; Figure 2 This is the surge lightning voltage waveform after adopting the present invention. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0020] like Figure 1 A surge lightning overvoltage protection system shown includes a five-pin controller; the first pin 1 of the controller is electrically connected to the emitter of the second switch tube Q2, the emitter of the third transistor Q3, the other end of the sampling resistor R1, the positive electrode of the voltage regulator tube Z1 and the other end of the sixteenth resistor R16.

[0021] The second pin 2 of the controller is electrically connected to one end of the sampling resistor R1 , the base of the second switch tube Q2 , and the source of the first MOS tube Q1 .

[0022] The third pin 3 of the controller is electrically connected to the collector of the second switch tube Q2, the collector of the third triode Q3, the gate of the first MOS tube Q1, the cathode of the voltage regulator tube Z1, one end of the tenth resistor R10, one end of the eleventh resistor R11, one end of the twelfth resistor R12 and one end of the thirteenth resistor R13.

[0023] The fourth pin 4 of the controller is electrically connected to the other end of the voltage-dividing resistor R14, the other end of the tenth resistor R10 and the other end of the eleventh resistor R11, and is electrically connected to the drain of the first MOS tube Q1 through the sixth resistor R6, the seventh resistor R7, the eighth resistor R8 and the ninth resistor R9 connected in series in sequence.

[0024] The fifth pin 5 of the controller is electrically connected to the other end of the twelfth resistor R12, the other end of the thirteenth resistor R13, the collector of the fourth triode Q4 and one end of the seventeenth resistor R17, and is electrically connected to the high voltage input end through the fifth resistor R5, the fourth resistor R4, the third resistor R3 and the second resistor R2 connected in series in sequence. The other end of the seventeenth resistor R17 is electrically connected to the base of the fourth triode Q4.

[0025] Assuming the output voltage is , we can obtain the following relationship:

[0026] in:

[0027] To just make the current flowing through R14 when Q3 / Q4 is turned on; is the BE voltage drop of the transistor; From the formula, we can get that when and When determined, the output voltage is only related to the resistance value of R14.

[0028] The control method is as follows: The current of the circuit is sampled by R1. When the voltage of R1 reaches the conduction point of Q2, it will lower the driving voltage of Q1, thereby increasing the impedance of Q1 to achieve the purpose of current limiting.

[0029] When the input voltage VH-GND is in the normal range, the voltage across R14 is small, Q4 does not work, and Q1 is turned on normally.

[0030] When the input voltage is higher than the target voltage, the voltage divided on R14 reaches the condition for turning on Q4; the turning on of Q4 causes Q3 to turn on, thereby lowering the drive of Q1, making the impedance of Q1 larger, thereby dividing the excess voltage on Q1; and the purpose of keeping the target voltage VH-VL unchanged.

[0031] like Figure 2 As shown in the figure, the surge lightning voltage waveform after adding this module; the residual voltage of MOS is only 510V, which can achieve a good surge lightning suppression effect.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A surge lightning overvoltage protection system, characterized in that: The invention comprises a controller, wherein a second pin (2) of the controller is electrically connected to one end of a sampling resistor (R1), a base of a second triode (Q2) and a source of a first MOS tube (Q1); a third pin (3) of the controller is electrically connected to a collector of the second triode (Q2), a collector of a third triode (Q3) and a gate of the first MOS tube (Q1); a first pin (1) of the controller is electrically connected to an emitter of the second triode (Q2), an emitter of the third triode (Q3) and the other end of the sampling resistor (R1) and is grounded; a base of the third triode (Q3) is electrically connected to an emitter of a fourth triode (Q4); a collector of the fourth triode (Q4) is electrically connected to a fifth pin (5) of the controller, a base of the fourth triode (Q4) is electrically connected to one end of a voltage divider resistor (R14), and the other end of the voltage divider resistor (R14) is electrically connected to a fourth pin (4) of the controller and a drain of the first MOS tube (Q1).

2. The surge lightning overvoltage protection system according to claim 1, characterized in that: The first pin (1) of the controller is electrically connected to the positive electrode of the voltage regulator tube (Z1), and the third pin of the controller is electrically connected to the negative electrode of the voltage regulator tube (Z1).

3. The surge lightning overvoltage protection system according to claim 1, characterized in that: The base of the third triode (Q3) is electrically connected to one end of a fifteenth resistor (R15) and one end of a sixteenth resistor (R16), the other end of the fifteenth resistor (R15) is electrically connected to the emitter of the fourth triode (Q4), and the other end of the sixteenth resistor (R16) is electrically connected to the emitter of the third triode (Q3), the emitter of the second triode (Q2) and the first pin (1) of the controller.

4. The surge lightning overvoltage protection system according to claim 1, characterized in that: The third pin (3) of the controller is also electrically connected to one end of the tenth resistor (R10) and one end of the eleventh resistor (R11); the other end of the tenth resistor (R10) and the other end of the eleventh resistor (R11) are electrically connected to the fourth pin (4) of the controller.

5. The surge lightning overvoltage protection system according to claim 1, characterized in that: The third pin (3) of the controller is also electrically connected to one end of a twelfth resistor (R12) and one end of a thirteenth resistor (R13); the other end of the twelfth resistor (R12) and the other end of the thirteenth resistor (R13) are both electrically connected to the fifth pin (5) of the controller.

6. The surge lightning overvoltage protection system according to claim 1, characterized in that: The fifth pin (5) of the controller is electrically connected to one end of a seventeenth resistor (R17), and the other end of the seventeenth resistor (R17) is electrically connected to the base of a fourth transistor (Q4).

7. The surge lightning overvoltage protection system according to claim 1, characterized in that: The fourth pin (4) of the controller is electrically connected to the drain of the first MOS tube (Q1) through a sixth resistor (R6), a seventh resistor (R7), an eighth resistor (R8) and a ninth resistor (R9) connected in series in sequence; the fifth pin (5) of the controller is electrically connected to the high-voltage input terminal through a fifth resistor (R5), a fourth resistor (R4), a third resistor (R3) and a second resistor (R2) connected in series in sequence; the sum of the resistance values ​​of the sixth resistor (R6), the seventh resistor (R7), the eighth resistor (R8) and the ninth resistor (R9) is equal to the sum of the resistance values ​​of the fifth resistor (R5), the fourth resistor (R4), the third resistor (R3) and the second resistor (R2).

8. The surge lightning overvoltage protection system according to claim 7, characterized in that: The designed output voltage is , then: ； The current flowing through the voltage divider resistor (R14) is just enough to make the third transistor (Q3) and the fourth transistor (Q4) conduct; is the sum of the resistance values ​​of the fifth resistor (R5), the fourth resistor (R4), the third resistor (R3) and the second resistor (R2); is the resistance value of the voltage divider resistor (R14); is the resistance value of the twelfth resistor (R12) and the thirteenth resistor (R13) connected in parallel, and the resistance value of the twelfth resistor (R12) and the thirteenth resistor (R13) connected in parallel is equal to the resistance value of the tenth resistor (R10) and the eleventh resistor (R11) connected in parallel; is the BE voltage drop of the fourth transistor (Q4).

9. A control method for a surge lightning overvoltage protection system according to any one of claims 1 to 8, characterized in that: The steps include: Step 1: When the input voltage VH-GND is within a normal range, the voltage across the voltage divider resistor (R14) is lower than a first preset value, the fourth transistor (Q4) does not work, and the first MOS tube (Q1) is normally turned on; Step 2: When the input voltage VH-GND is higher than the preset voltage, the voltage across the voltage-dividing resistor (R14) is greater than or equal to the first preset value, the fourth transistor (Q4) is turned on, and the fourth transistor (Q4) turns on to cause the third transistor (Q3) to turn on, thereby lowering the driving voltage of the first MOS tube (Q1), increasing the impedance of the first MOS tube (Q1), and dividing the excess voltage onto the first MOS tube (Q1), thereby keeping the target voltage VH-VL unchanged; Step 3: The sampling resistor (R1) performs current sampling. When the current reaches a second preset value, the second transistor (Q2) is turned on, the driving voltage of the first MOS tube (Q1) is pulled down, and the impedance of the first MOS tube (Q1) is increased until the driving voltage of the first MOS tube (Q1) divided by the impedance is equal to the design current, thereby achieving current limiting.

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