Totem pole bridgeless PFC circuit slow tube lightning protection circuit

Abstract

The utility model relates to a totem pole bridgeless PFC (power factor correction) circuit slow tube lightning protection circuit, which comprises a lightning protection module and a discharge circuit, two MOS (metal oxide semiconductor) tubes and two current transformers are arranged at the front end of an output end of an L line, each current transformer is connected with a corresponding MOS tube, a main circuit is sampled by the current transformers so as to detect abrupt change large current on the main circuit, and the abrupt change large current is detected by the discharge circuit. And when large current is detected, the corresponding MOS tube is closed, and when abrupt change large current exists on the main circuit, the abrupt change large current is released through a parasitic diode in the MOS tube. Therefore, the MOS tube of the slow tube is effectively protected, the reliability and the stability of the whole power supply system are improved, and the whole circuit is simple and effective in structure, quick in response and capable of being widely applied to lightning protection facilities.

Description

Technical Field

[0001] The utility model relates to the technical field of lightning protection circuit protection, in particular to a slow tube lightning protection circuit for a totem pole bridgeless PFC circuit. Background Art

[0002] In the field of power supply circuits, protecting circuits from external factors such as lightning strikes and other emergencies is a crucial challenge. Based on the slow tube in the totem pole bridgeless PFC circuit, it is easily damaged during lightning strike tests, resulting in abnormal operation of the entire system. To address the problem of easy damage to the slow tube, existing overvoltage protection schemes often fail to provide sufficient protection and are difficult to effectively ensure the stable and reliable operation of the circuit.

[0003] For example, the Chinese invention patent application with the publication number CN 107959334 A provides a new type of wireless charging system, including a transmitting end and a receiving end. The transmitting end includes an EMC filtering module, and the EMC filtering module includes a lightning protection circuit, a first filtering circuit, a second filtering circuit, and a rectifier bridge D5. The transmitting end is connected to the mains through a two-phase three-wire plug, and the output end of the two-phase plug is connected to the lightning protection circuit through terminals J1, J2, and J3. The lightning protection circuit includes a varistor MOV1, a varistor MOV2, a varistor MOV3, a fuse F1, and a gas discharge tube G1. When encountering a lightning strike, the lightning protection circuit only discharges through the gas discharge tube G1. However, the response time of the gas discharge tube is as high as several hundred ns to several ms, which is the slowest among protection devices. When the lightning overvoltage on the cable breaks down and shorts the gas discharge tube in the lightning arrester, the initial breakdown voltage is basically the impact breakdown voltage of the gas discharge tube. After the discharge tube breaks down and conducts, the voltage between the two poles drops to 20 - 50V. On the other hand, the current-carrying capacity of the gas discharge tube is larger than that of the varistor and the TVS tube. Therefore, some lightning protection circuits also use the gas discharge tube in combination with protection devices such as TVS, so that most of the overcurrent is discharged through the gas discharge tube. The gas discharge tube is generally used for the front stage of the protection circuit, and the subsequent protection circuit is composed of a varistor or a TVS tube. The response time of these two devices is very fast, and the protection effect on the subsequent circuit is better. However, in a long-term lightning environment, sudden currents frequently occur, and it is necessary to more sensitively sense current changes and make timely response actions to prevent devices such as TVS tubes from being damaged by excessive lightning energy. Summary of the Utility Model

[0004] In view of this, a slow tube lightning protection circuit for a totem pole bridgeless PFC circuit with a simple and effective circuit structure, fast and sensitive response, and capable of automatically shutting down and protecting the MOS tube is provided.

[0005] A slow-switch lightning protection circuit for a totem-pole bridgeless PFC circuit, comprising a lightning protection module and a discharge circuit. The lightning protection module is connected between the L line of the AC input terminal and the N line of the AC input terminal. The slow-switch lightning protection circuit for the totem-pole bridgeless PFC circuit further includes a second MOS transistor Q2, a ninth MOS transistor Q9, a second current transformer CT2, and a third current transformer CT3 provided at the front end of the L line output terminal. The source electrode of the second MOS transistor Q2 is connected to the positive output terminal DC+ of the entire lightning protection circuit through the second current transformer CT2. The source electrode of the ninth MOS transistor Q9 is connected to the ground terminal GND through the third current transformer CT3. The gate electrodes of the second MOS transistor Q2 and the ninth MOS transistor Q9 are respectively connected to a single-chip microcomputer. The second current transformer CT2 and the third current transformer CT3 form a sampling circuit to detect a large sudden current on the main path and send a signal to the single-chip microcomputer when a large current is detected. After receiving the signal, the single-chip microcomputer turns off the corresponding MOS transistor. When there is a large sudden current on the main path, the large sudden current is released through the parasitic diode inside the MOS transistor.

[0006] Further, the source electrode of the second MOS transistor Q2 is connected to the rear end of the L line of the lightning protection module, the drain electrode is connected to the fourth terminal of the second current transformer CT2, the third terminal of the second current transformer CT2 is connected to the positive output terminal DC+ of the entire lightning protection circuit, the drain electrode of the ninth MOS transistor Q9 is connected to the fourth terminal of the third current transformer CT3, the source electrode is connected to the ground terminal GND, and the third terminal of the third current transformer CT3 is connected to the rear end of the L line of the lightning protection module.

[0007] Further, each of the second current transformer CT2 and the third current transformer CT3 includes two mutual inductance parts. One mutual inductance part is connected to the single-chip microcomputer to give a signal to the single-chip microcomputer, and the other mutual inductance parts CT2-B and CT3-B each have the third terminal and the fourth terminal.

[0008] Further, the slow-switch lightning protection circuit for the totem-pole bridgeless PFC circuit further includes a first MOS transistor Q1 and a third MOS transistor Q3 provided at the front end of the N line output terminal. The drain electrode of the first MOS transistor Q1 is connected to the positive output terminal DC+ of the entire lightning protection circuit, the source electrode is connected to the rear end of the N line of the lightning protection module, the source electrode of the third MOS transistor Q3 is connected to the ground terminal GND, the drain electrode is connected to the rear end of the N line of the lightning protection module, and the gate electrodes of the first MOS transistor Q1 and the third MOS transistor Q3 are respectively connected to the single-chip microcomputer.

[0009] Further, a bus filter capacitor C68 is connected in parallel between the positive output terminal DC+ and the ground terminal GND.

[0010] Further, an external PFC inductor L1 is connected to the front-end line of the L line connected to the second MOS transistor Q2, and the winding led out by the PFC inductor L1 is connected to a zero-crossing detection circuit for providing a zero-crossing detection signal to the single-chip microcomputer.

[0011] Further, the lightning protection module is connected between the L line at the AC input end and the N line at the AC input end, and the third pin is grounded. The discharge circuit includes a first varistor MOV1, a second varistor MOV2, a third varistor VR2, and a discharge tube G1. The first varistor MOV1 and the second varistor MOV2 are connected in series and then connected in parallel with the third varistor VR2 between the L line and the N line at the rear end of the lightning protection module. The two series-connected varistors MOV1 and MOV2 are connected in parallel with the input capacitor between the L line and the N line. The series connection point of the two series-connected varistors MOV1 and MOV2 is connected to one end of the discharge tube G1, and the other end of the discharge tube G1 is grounded.

[0012] Further, the lightning protection module includes a first group of capacitors and a second capacitor connected in parallel between the L line and the N line. The first group of capacitors includes a series-connected second 92 capacitor C292 and a second 93 capacitor C293. The second group of capacitors includes a series-connected first capacitor CY1 and a second capacitor CY2.

[0013] Further, a first group of fuses is connected between the L line of the lightning protection module and the front end of the varistor VR2 at the rear end of the two groups of capacitors, and a second group of fuses is connected between the N line of the lightning protection module and the varistor VR2 between the two groups of capacitors. Each group of fuses includes a pair of fuses.

[0014] In the above-mentioned totem-pole bridgeless PFC circuit slow transistor lightning protection circuit, when the circuit is subjected to common-mode lightning strikes, the current transformer detects a large current mutation in the main circuit, turns off the drive of the MOS transistor of the slow transistor, and makes it impossible to form a conductive channel inside the MOS. Therefore, the current can only pass through the parasitic diode inside the MOS transistor, and the excess energy is discharged by the varistor in the circuit and absorbed by the absorption capacitor, and finally flows back to the negative electrode to form a path. The impact resistance of the parasitic diode inside the MOS transistor is much greater than that of the conductive channel formed by the MOS, so the slow transistor is effectively protected, improving the reliability and stability of the entire power supply system. The overall circuit structure is simple and effective, with fast response, and can be widely used in lightning protection facilities. Description of the Drawings

[0015] Figure 1 is a schematic structural diagram of a totem-pole bridgeless PFC circuit slow transistor lightning protection circuit provided by an embodiment of the present invention. Detailed Embodiments

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts belong to the scope of protection of the present utility model.

[0017] Please refer to Figure 1 , which shows a slow tube lightning protection circuit for a totem pole bridgeless PFC circuit provided by an embodiment of the present utility model, including a lightning protection module and a discharge circuit. The lightning protection module is connected between the L line of the AC input end and the N line of the AC input end. The slow tube lightning protection circuit of the totem pole bridgeless PFC circuit further includes a second MOS transistor Q2, a ninth MOS transistor Q9, a second current transformer CT2, and a third current transformer CT3 provided at the front end of the output end of the L line. The source electrode of the second MOS transistor Q2 is connected to the positive output terminal DC+ of the entire lightning protection circuit through the second current transformer CT2. The source electrode of the ninth MOS transistor Q9 is connected to the ground terminal GND through the third current transformer CT3. The gate electrodes of the second MOS transistor Q2 and the ninth MOS transistor Q9 are respectively connected to the single-chip microcomputer. The second current transformer CT2 and the third current transformer CT3 form a sampling circuit to detect a sudden large current on the main circuit and send a signal to the single-chip microcomputer when a large current is detected. After receiving the signal, the single-chip microcomputer turns off the corresponding MOS transistor. When there is a sudden large current on the main circuit, the sudden large current is released through the parasitic diode inside the MOS transistor. Usually, according to different lightning strike voltage levels and different current magnitudes, that is, the sudden large current will have certain differences. For example, when a common-mode and differential-mode lightning strike of 4000 - 6000V is applied, the sudden current is above 100A.

[0018] Specifically, the source electrode of the second MOS transistor Q2 is connected to the rear end of the L line of the lightning protection module, the drain electrode is connected to the fourth terminal of the second current transformer CT2, the third terminal of the second current transformer CT2 is connected to the positive output terminal DC+ of the entire lightning protection circuit, the drain electrode of the ninth MOS transistor Q9 is connected to the fourth terminal of the third current transformer CT3, the source electrode is connected to the ground terminal GND, and the third terminal of the third current transformer CT3 is connected to the rear end of the L line of the lightning protection module.

[0019] Furthermore, each of the second current transformer CT2 and the third current transformer CT3 includes two mutual inductance parts. One mutual inductance part of each is connected to the single-chip microcomputer to give a signal to the single-chip microcomputer, and the other mutual inductance parts CT2-B and CT3-B each have the third terminal and the fourth terminal.

[0020] Furthermore, the slow-switch lightning protection circuit of the totem-pole bridgeless PFC circuit further includes a first MOS transistor Q1 and a third MOS transistor Q3 provided at the front end of the N-line output terminal. The drain of the first MOS transistor Q1 is connected to the positive output terminal DC+ of the entire lightning protection circuit, and the source is connected to the rear end of the N-line of the lightning protection module. The source of the third MOS transistor Q3 is connected to the ground terminal GND, and the drain is connected to the rear end of the N-line of the lightning protection module. The gates of the first MOS transistor Q1 and the third MOS transistor Q3 are respectively connected to the single-chip microcomputer. The L-line output terminal DC+ is usually the power supply terminal for the load or other devices.

[0021] In this embodiment, the single-chip microcomputer is not shown in the figure. Some conventional single-chip microcomputers can achieve the above functions. The single-chip microcomputer has multiple pins, which are respectively connected to each current transformer and the gates of each MOS transistor to transmit signal commands. When the second current transformer CT2 or the third current transformer CT3 respectively detects that a large current passes through, the signal is transmitted to the single-chip microcomputer, and the single-chip microcomputer sends a driving signal to the driving circuit, and then the driving circuit controls the corresponding MOS transistor to turn off, that is, the single-chip microcomputer stops sending PWM waves, and the driving waves stop. On the contrary, when a normal current passes through, the single-chip microcomputer controls the normal driving output.

[0022] Preferably, a bus filter capacitor C68 is connected in parallel between the positive output terminal DC+ and the ground terminal GND. The capacitor C68 is preferably an electrolytic capacitor or a film capacitor with a large capacitance, preferably 470 uF / 500V. The capacitor C68 serves as the bus capacitor of the PFC circuit, and its main function is to improve the stability and transient response of the power supply, and filter to reduce the ripple.

[0023] In addition, a PFC inductor L1 is externally connected to the front-end line of the L-line connected to the second MOS transistor Q2. The winding led out by the PFC inductor L1 is connected to the zero-crossing detection circuit to provide a zero-crossing detection signal for the single-chip microcomputer. The PFC inductor L1 can also control the on and off of the above-mentioned MOS transistors, but the signals are separated from those of the current transformer and are independent of each other, belonging to different state controls. The PFC inductor L1 feeds back to the single-chip microcomputer to achieve voltage-current phase tracking and control the PFC value.

[0024] As Figure 1As shown, specifically, the lightning protection module is connected between the L line of the AC input terminal and the N line of the AC input terminal, and the third pin is grounded. The discharge circuit includes a first varistor MOV1, a second varistor MOV2, a third varistor VR2, and a discharge tube G1. The first varistor MOV1 and the second varistor MOV2 are connected in series and then connected in parallel with the third varistor VR2 between the L line and the N line at the rear end of the lightning protection module. The two series-connected varistors MOV1 and MOV2 are connected in parallel with the input capacitor between the L line and the N line. The series connection point of the two series-connected varistors MOV1 and MOV2 is connected to one end of the discharge tube G1, and the other end of the discharge tube G1 is grounded.

[0025] Furthermore, the lightning protection module includes a first group of capacitors and a second capacitor connected in parallel between the L line and the N line. The first group of capacitors includes a series-connected 292nd capacitor C292 and 293rd capacitor C293. The capacitances of the 292nd capacitor C292 and the 293rd capacitor C293 are the same, preferably 472 pF / 500V. The second group of capacitors includes a series-connected first capacitor CY1 and second capacitor CY2. The capacitances of the first capacitor CY1 and the second capacitor CY2 are the same, preferably 220 pF / 500V.

[0026] Further, a first group of fuses is connected between the L line of the lightning protection module and the front end of the varistor VR2 at the rear end of the two groups of capacitors, and a second group of fuses is connected between the N line of the lightning protection module and the varistor VR2 between the two groups of capacitors. Each group of fuses includes a pair of fuses, and the specifications of each pair of fuses are basically the same. For example, they are 40A 250V respectively.

[0027] During a lightning strike, the lightning energy first starts from the input terminal. Most of the energy is discharged to the ground through the lightning protection module, and the excess lightning energy flows through the varistor and the discharge tube G1 to the ground for release; a small amount of lightning energy remains in the circuit and flows through the slow tube (i.e., the rear-end MOS tube). Since the slow tube has a relatively long turn-on time, to avoid damage to the MOS tube caused by a large current formed by the residual lightning energy, the main circuit sudden large current is detected by the corresponding current transformer, and the MOS tube is turned off, so that no conductive channel can be formed inside the MOS. Thus, the current can only pass through the parasitic diode inside the MOS tube, and the excess energy is then discharged by the varistor in the circuit and absorbed by the absorption capacitor, and finally flows back to the negative pole to form a path. The impact resistance of the parasitic diode inside the MOS tube is much greater than that of the conductive channel formed by the MOS, so the slow tube is effectively protected, improving the reliability and stability of the entire power supply system.

[0028] It should be noted that the present utility model is not limited to the above embodiments. According to the creative spirit of the present utility model, those skilled in the art can also make other changes, and these changes made according to the creative spirit of the present utility model should all be included within the scope protected by the present utility model.

Claims

1. A totem pole bridgeless PFC circuit slow tube lightning protection circuit, comprising a lightning protection module and a discharge circuit, wherein the lightning protection module is connected between the L line of the AC input terminal and the N line of the AC input terminal, characterized in that: The totem pole bridgeless PFC circuit slow tube lightning protection circuit also includes a second MOS tube Q2, a ninth MOS tube Q9, a second current transformer CT2 and a third current transformer CT3 arranged at the front end of the L line output end. The source of the second MOS tube Q2 is connected to the positive output end DC+ of the entire lightning protection circuit through the second current transformer CT2, the source of the ninth MOS tube Q9 is connected to the ground end GND through the third current transformer CT3, the gate of the second MOS tube Q2 and the gate of the ninth MOS tube Q9 are respectively connected to the single chip microcomputer, the second current transformer CT2 and the third current transformer CT3 constitute a sampling circuit to detect a sudden large current on the main line and send a signal to the single chip microcomputer when a large current is detected. After receiving the signal, the single chip microcomputer turns off the corresponding MOS tube. When there is a sudden large current on the main line, the sudden large current is released through the parasitic diode inside the MOS tube.

2. The totem pole bridgeless PFC circuit slow tube lightning protection circuit according to claim 1, characterized in that: The source of the second MOS tube Q2 is connected to the rear end of the lightning protection module L line, and the drain is connected to the fourth end of the second current transformer CT2. The third end of the second current transformer CT2 is connected to the positive output end DC+ of the entire lightning protection circuit. The drain of the ninth MOS tube Q9 is connected to the fourth end of the third current transformer CT3, and the source is connected to the ground end GND. The third end of the third current transformer CT3 is connected to the rear end of the lightning protection module L line.

3. The totem pole bridgeless PFC circuit slow tube lightning protection circuit as claimed in claim 2, characterized in that: The second current transformer CT2 and the third current transformer CT3 each include two mutual inductance parts, each having one mutual inductance part connected to the single chip microcomputer to give a signal to the single chip microcomputer, and the other mutual inductance parts CT2-B and CT3-B each have the third terminal and the fourth terminal.

4. The totem pole bridgeless PFC circuit slow tube lightning protection circuit according to claim 1, characterized in that: The totem pole bridgeless PFC circuit slow tube lightning protection circuit also includes a first MOS tube Q1 and a third MOS tube Q3 arranged at the front end of the N line output end, the drain of the first MOS tube Q1 is connected to the positive output end DC+ of the entire lightning protection circuit, and the source is connected to the rear end of the N line of the lightning protection module, the source of the third MOS tube Q3 is connected to the ground terminal GND, and the drain is connected to the rear end of the N line of the lightning protection module, and the gate of the first MOS tube Q1 and the gate of the third MOS tube Q3 are respectively connected to the single-chip microcomputer.

5. The totem pole bridgeless PFC circuit slow tube lightning protection circuit according to claim 1, characterized in that: A bus filter capacitor C68 is connected in parallel between the positive output terminal DC+ and the ground terminal GND.

6. The totem pole bridgeless PFC circuit slow tube lightning protection circuit according to claim 1, characterized in that: The L line is externally connected to a PFC inductor L1 on the front end line connected to the second MOS tube Q2, and the winding led out of the PFC inductor L1 is connected to a zero-crossing detection circuit for providing a zero-crossing detection signal to the single-chip microcomputer.

7. The totem pole bridgeless PFC circuit slow tube lightning protection circuit according to claim 1, characterized in that: The lightning protection module is connected between the L line of the AC input end and the N line of the AC input end, and the third pin is grounded. The discharge circuit includes a first varistor MOV1, a second varistor MOV2, a third varistor VR2, and a discharge tube G1. The first varistor MOV1 and the second varistor MOV2 are connected in series and connected in parallel with the third varistor VR2 between the rear end L line and the N line of the lightning protection module. The two series-connected varistors MOV1 and MOV2 are connected in parallel with the input capacitor between the L line and the N line. The series connection point of the two series-connected varistors MOV1 and MOV2 is connected to one end of the discharge tube G1, and the other end of the discharge tube G1 is grounded.

8. The totem pole bridgeless PFC circuit slow tube lightning protection circuit according to claim 1, characterized in that: The lightning protection module includes a first group of capacitors and a second group of capacitors connected in parallel between the L line and the N line, the first group of capacitors includes a second ninety-two capacitor C292 and a second ninety-three capacitor C293 connected in series, and the second group of capacitors includes a first capacitor CY1 and a second capacitor CY2 connected in series.

9. The totem pole bridgeless PFC circuit slow tube lightning protection circuit according to claim 7, characterized in that: The L line of the lightning protection module is connected with a first group of fuses between the rear ends of the two groups of capacitors and the front end of the varistor VR2, and the N line of the lightning protection module is connected with a second group of fuses between the two groups of capacitors and the varistor VR2, and each group of fuses includes a pair of fuses.

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