KR101171739B1 - A switch power source cycle by cycle overvoltage protection circuit - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a kind of switch power frequency overvoltage protection circuit, and includes a thyristor (SCR), a constant voltage diode (TVS), a first register (R1), a second register (R2), and a second diode ( D2) and a second capacitor (C2), the positive electrode and the AC input terminal (ACIT) of the thyristor (SCR) is connected to each other, the negative electrode and the load terminal (LDT) are connected to each other, The first resistor R1 of which the cathode of the constant voltage diode (TVS) and the gate of the thyristor (SCR) are connected to each other, and the anodes of the constant voltage diode (TVS) are connected to each other in parallel. And a second resistor (R2) are connected to each other, the first resistor (R1) is directly connected to the AC input terminal (ACIT), the second resistor (R2) in the reverse direction of the constant voltage diode (Zener Diode) (TVS) After connecting with the installed second diode D2, The second capacitor C2 is connected to the input terminal ACIT, and is connected between the thyristor (SCR) cathode and the constant voltage diode (TVS) cathode, and the load input terminal LDT and the load ground terminal ( A first capacitor C1 is connected between the LDGTs.

Description

Switch power frequency overvoltage protection circuit {A SWITCH POWER SOURCE CYCLE BY CYCLE OVERVOLTAGE PROTECTION CIRCUIT}

TECHNICAL FIELD The present invention relates to the field of overvoltage protection technology, and more particularly, to a type of switch power supply overvoltage protection circuit.

Some power environments do not disassemble 220 VAC and 380 VAC easily, under complex and harsh conditions, when the power system voltage is not stable, the power input inputs overvoltage, and accumulates in the internal components of the switch power portion of the electronic equipment. Capacitors, etc., are typically damaged by accepting overvoltages and affect the normal operation of all electronic devices.

In such a situation, in order to protect electronic equipment, a commonly used method is to add an overvoltage protection circuit to a power input terminal, and several methods are commonly used as follows.

Method 1: Using a common protection method of fuse positive temperature coefficient (CFC) and metal oxide varistor (MOV) metal oxide varistor (MOV), as shown in FIG. At this time, the resistance value of the varistor drops sharply, forms a large current circuit, the PPTC rapidly heats through the large current, turns into a high resistance state, and the current limit through the circuit is very small, so that the power supply post circuit It can achieve its purpose. However, this method has the disadvantage that the varistor's service life is short, response time is slow, and once protection is started, power is always cut off and continuous operation is possible only when the PPTC has cooled down and returned to a low resistance state. There is this.

Method 2: Method 2 is an improved version of Method 1, in which a varistor is used to replace the varistor, and as shown in FIG. 2, the Zener diode overcomes the deficiencies of the varistor, so that the response time is improved. Extremely fast, long service life, high voltage clamp consistency, high voltage across the Zener Diode when the AC input is input higher than the Voltage Clamp of the Zener Diode. Immediately reduces the resistance of the Zener Diode and also places a clamp of the voltage on the Voltage Clamp of the Zener Diode to form a large current circuit, and PPTC quickly Since the heat is generated, turned into a high resistance state, and the current limit through the circuit is very small, the object of protecting the power supply post circuit can be achieved. However, this method has the drawback that once protection is started, power is always cut off and continuous operation is possible only when the PPTC cools and returns to a low resistance state.

Method 3: Adopting thyristor overvoltage protection method, as shown in Fig. 3, when the AC input voltage rises to the setting voltage of the protection circuit (if the R1 and R2 resistance values are converted, the setting voltage is converted immediately), Trigger diode DS Break Over, Thyristor break-over, current passes through PPTC, thyristor current limiting resistor R3, thyristor forms a large current circuit, PPTC heats quickly through the large current, high resistance state Since the current limit through the circuit is very small, the purpose of protecting the power supply post circuit can be achieved. However, this method has a drawback that once the protection of the PPTC is started, the power is always cut off, and continuous operation is possible only when the PPTC is cooled and returned to a low resistance state.

Method 4: The Thyristor suppression protection method is adopted, as shown in Fig. 4, the principle is as follows. The control circuit is controlled based on the magnitude of the AC input voltage, and by comparing and calculating the circuits, an appropriate delay trigger pulse is output, and the thyristor break-over time is controlled so that the switch power supply post circuit is controlled. Ensure that the voltage does not exceed the maximum operating voltage. Although the above protection method is good, there are disadvantages in that the circuit control is very complicated, the cost of realization is high, and it is difficult to be used in a switch power supply with a small power.

Method 5: The relay overvoltage protection method is adopted, after the AC input voltage is raised, the DC voltage after rectification is also increased, and when the DC voltage is higher than the voltage clamp of the Zener diode, Zener Diode) is passed through, triode Q1 break-over, relay operation, interlocking phase close contact, can cut off the post (End / Post) power supply circuit to achieve the purpose of input overvoltage protection. Although the above scheme is simple and reliable, in the case of large voltage fluctuations, the relay is frequently operated, affecting the continuous and stable power supply of the power supply. There is a drawback that it has to be provided, and it is also difficult to use in a switch power supply with large volume and small power.

The present invention, in order to solve the above problems appearing in the switch power frequency overvoltage protection circuit currently commercially available, through the thyristor AC chopper principle, directly extract the power system voltage, based on the magnitude of the AC input voltage, Its purpose is to provide an automatic switching of the power switch overvoltage protection circuit of the thyristor break-over time.

The present invention adopts the following technical solution to solve the technical problem. A kind of switch power frequency overvoltage protection circuit, wherein a first overvoltage protection circuit is connected between an AC input and a load, and the first overvoltage protection circuit includes a thyristor, a zener diode, and a first register. And a second resistor, a second diode, and a second capacitor, wherein a positive electrode and an AC input terminal of the thyristor are connected to each other, a negative electrode and a load terminal of the thyristor are connected to each other, and the Zener Diode ) The cathode and the gate of the thyristors are connected to each other, the anodes of the constant voltage diodes (Zener Diode) are connected on the first resistor and the second resistor are connected in parallel with each other, the first resistor is directly connected to the alternating current It is connected to the input terminal and the second resistor is installed in the reverse direction of the Zener Diode. After the connection with the second diode, being connected to each other and exchange the input terminal, a second capacitor (Capacitor) is connected between the thyristor anode and a constant voltage diode (Zener Diode) cathode.

A first capacitor is connected between the load input terminal and the load ground terminal.

According to a preferred embodiment of the present invention, a first diode is installed between the thyristor cathode and the load terminal in the same direction as the thyristor.

According to a preferred embodiment of the present invention, a third resistor is connected between the first diode anode and the common ground end.

According to a preferred embodiment of the present invention, it also includes a third diode, the cathode and the third resistor of the third diode is connected in series with each other, the cathode and the third resistor of the third diode is connected to each other The anode and the common ground are connected to each other.

According to one preferred embodiment of the present invention, a second overvoltage protection circuit is connected between the AC input and the load, and the single phase second overvoltage protection circuit includes a thyristor, a constant voltage diode, a first resistor, and a second resistor. And a third resistor, a first diode, a second diode, a third diode, and a second capacitor, wherein the anode and the common ground of the thyristor are connected to each other, and the cathode of the thyristor is the same as the thyristor. It is connected to the load terminal through the first diode which is connected in series in the direction, the anode of the Zener Diode and the gate of the thyristor are connected to each other, the cathode of the Zener Diode are mutually Are connected on the first and second registers connected in parallel, and the first register is directly The second resistor is connected to the same ground, and the second resistor is connected to the second diode installed in the same direction as the Zener Diode, and then to the common ground, and the second capacitor is connected to the thyristor cathode and the constant voltage. It is connected between the diode (Zener Diode) anode, the third resistor and the third diode is connected in series is installed between the first diode anode and the AC input terminal, the cathode and the third diode of the third diode is connected to each other The anode and the AC input terminal of the third diode are connected to each other.

According to an exemplary embodiment of the present invention, a third overvoltage protection circuit is connected between the AC input terminal and the load ground terminal, and the third overvoltage protection circuit includes a thyristor, a constant voltage diode, a first resistor, and a second resistor. And a second capacitor and a second diode, the anode and the load terminal of the thyristor are connected to each other, the cathode and the AC input terminal of the thyristor are connected to each other, and the cathode diode cathode The gates of the and thyristors are connected to each other, and the anodes of the constant voltage diodes are connected to the first and second resistors which are connected in parallel to each other, and the first resistor is directly connected to the load ground. The second resistor is connected to the reverse side of the constant voltage diode. Through a diode, they are connected to each other and the load Gdansk, a second capacitor (Capacitor) is connected between the thyristor anode and a constant voltage diode (Zener Diode) cathode.

According to a preferred embodiment of the present invention, a third diode is provided in the first overvoltage protection circuit, the anode and the common ground of the third diode are connected to each other, and the cathode and the load of the third diode are connected to each other. It is connected.

According to a preferred embodiment of the present invention, there is also a third diode is installed, the third diode is connected on the common ground and the load ground cable, the anode of the third diode and the first capacitor (Capacitor) cathode The cathode of the third diode and the anode of the third diode of the first overvoltage protection circuit are connected to each other.

An advantageous effect of the present invention is to extract the power system voltage directly through a thyristor AC chopper, and automatically convert the break-over time of the thyristor based on the magnitude of the AC input voltage to control the frequency of the AC input power. By avoiding the shortcomings of slowing response time and enabling automatic immediate correction of power system voltage fluctuations, it achieves the overvoltage protection objectives of the post / end power circuit.

1 is a conventional first circuit diagram;
2 is a second conventional circuit diagram;
3 is a conventional third circuit diagram;
4 is a typical fourth circuit diagram;
5 is a typical fifth circuit diagram;
6 is a basic circuit diagram of single phase half wave overvoltage protection of the present invention;
7 is an enlarged circuit diagram of single phase half wave overvoltage protection of the present invention;
8 is a basic circuit diagram of full wave overvoltage protection of the present invention;
9 is an enlarged circuit diagram of full wave overvoltage protection of the present invention;
10 is a waveform perspective view of a single phase half wave overvoltage protection basic circuit;
Fig. 11 is a perspective view of a voltage waveform of point A of a single phase half wave overvoltage protection basic circuit.

The following specific exemplary manner describes the technical solution of the present invention in more detail with the accompanying drawings.

Embodiment 1: As shown in Fig. 6, a single phase half wave overvoltage protection basic circuit is provided between an AC input and a load, and includes a first overvoltage protection circuit 1, a diode D1, and a resistor R3. ) And a capacitor C1. The basic circuit structure of the single-phase half-wave overvoltage protection includes a thyristor (SCR), and the anode and the AC input terminal of the thyristor (SCR) are connected to each other, and the cathode is installed in the same direction as the thyristor (SCR). After being connected to (D1), it is connected to each other and the load terminal, and also includes one of the Zener Diode (TVS), the gate of the Zener Diode (TVS) cathode and thyristor (SCR) (Gate) Are connected to each other, and the anodes of the Zener Diodes (TVS) are connected to the resistors R1 and R2 which are connected in parallel with each other, and the resistors R1 are directly connected to the AC input terminal. The resistor (R2) is connected to the diode (D2) installed in the reverse direction of the Zener Diode (TVS), and then connected to the AC input terminal, thyristor (SCR) A capacitor (C2) is connected between the pole and the cathode of the Zener Diode (TVS), and a resistor (R3) is installed, and the resistor (R3) is connected between the anode of the diode (D1) and the AC input terminal. The capacitor C1 is connected between the load input terminal and the load ground terminal. The thyristor (SCR), diode (D1), capacitor (Cacitor) (C1) constitutes a current output main circuit. The resistor R1, the constant voltage diode TVS, the capacitor C2, and the resistor R3 generate the first control circuit of the thyristor trigger pulse. The diode D2, the resistor R2, the Zener Diode TVS, the capacitor C2, and the resistor R3 generate a second control circuit of the thyristor trigger pulse.

The principle of operation of the circuit is as follows. When the AC input is at the start of the positive half cycle, the pulse trigger stage A stage of the thyristor (SCR) gradually becomes a low level phenomenon, and the A point voltage is shown in FIG. 11, the thyristor (SCR). At this time, the C voltage is higher than the point B, the diode D1 is in the reverse closing state, the accumulated energy capacitor C1 is not discharged in the input circuit in the reverse direction, and is positive half cycle. As the voltage of the cycle gradually rises, current passes through the first control circuit, and the resistor R1, the Zener Diode TVS, and the resistor R3 are in the forward direction toward the capacitor C2. At this time, the Zener Diode (TVS) is in a forward breakover state, and as the voltage of the AC input positive half cycle gradually rises, the voltage at the point A also becomes When the voltage at point A exceeds the thyristor gate trigger voltage (VSCR), the thyristor SCR is braked over, and the capacitor C2 is charged. The forward charging time of the capacitor C2 is referred to as TC2 +, as shown in FIG.

After the thyristor (SCR) break-over, the point B voltage gradually rises, and the point B voltage rises to the point C voltage VC1 (voltage C1 short voltage) + 0.7 V (forward pressure drop of the diode D1). When exceeded, D1 breaks over, current is charged in the direction of capacitor C1 through the main circuit, point C voltage VC1 gradually rises, and voltage of positive half cycle gradually increases. As the voltage falls, the point B voltage also gradually decreases, and when the point B voltage is lower than the point C voltage (VC1 + 0.7V), D1 is closed and charging of the capacitor C1 is completed. The charging time of (Capacitor) C1 is referred to as TC1, as shown in FIG.

Since the resistance of the resistor R3 is very large, the current flowing in the thyristor SCR is smaller than the holding current of the thyristor, the thyristor SCR is closed, and the disconnected current is output to the main circuit. The breakover time of the SCR is called TSCR as shown in FIG.

At this time, the current flowing to the thyristor (SCR) immediately exceeds the holding current, the thyristor (SCR) breaks over, but as the input voltage decreases to zero, the thyristor (SCR) is also automatically closed, and the disconnected current Output to the main circuit.

Since the charge time TC1 of the capacitor C1 and the breakover time TSCR of the thyristor SCR are directly proportional to each other, the longer the breakover time TSCR of the thyristor SCR becomes, the capacitor ( The voltage VC1 on C1) also gradually increases. The breakover of the thyristor SCR causes the gate to reach the trigger voltage VSCR from the gate control, and the longer the time point A voltage VC2 reaches the time TC2 + of the VSCR, the more the thyristor The breakover time TSCR of the SCR gradually decreases, and the voltage on the accumulated energy capacitor C1 also gradually decreases. Therefore, if only the forward charge time TC2 + of C2 can be controlled well, the voltage VC1 on the capacitor C1 can be placed within the safe use range, thereby realizing the purpose of protecting the load circuit. . However, this must be assumed that the AC input voltage must be stable. If the AC input voltage suddenly rises, the charging current in the first control circuit also increases correspondingly, and the gate trigger voltage VSCR Time TC2 + is shortened, the thyristor SCR breakover time TSCR is extended to extend the charge time TC1 on capacitor C1, and the voltage on capacitor C1. (VC1) will also increase correspondingly. Also, as a matching second control circuit, it is possible to solve the charging time TC1 control on the capacitor C1 of the first control circuit.

Within the positive half cycle frequency of the AC input, the diode D2 in the second control circuit is closed in reverse to render the second control circuit inoperable and to enter the negative half cycle frequency. When the negative pressure is small, the Zener Diode (TVS) does not break over and is in a high resistance state, and only a small leakage current is present in the control circuit. The effect on is very insignificant, and the voltage at point A is basically unchanged.

As the negative voltage increases, when the negative voltage exceeds the voltage clamp (VTVS) of the Zener Diode (TVS), the resistance of the Zener Diode (TVS) immediately decreases, The voltage clamp is also placed on the voltage clamp of the Zener Diode TVS to form one reverse charging circuit for the capacitor C2 of the second control circuit. , The voltage at point A is changed from positive pressure to negative pressure, and as shown in Fig. 10, the negative pressure at point A is called VC2-, and the charging time for C2 is called TC2-.

If the AC input voltage increases (increasing the AC input negative pressure), the reverse charging current increases, and the time to pass through the Zener Diode TVS tube must be advanced, so that the reverse direction to the capacitor (C2) The charging time TC2- increases. C2 causes higher negative pressure (VC2-0) formation at point A because the charging time is extended and the charging current is increased. The magnitude of the negative pressure VC2- formed at the point A is that the first control circuit has an AC input positive half cycle. In frequency It affects the forward charging time of the capacitor C2, and as the negative pressure VC2- of the A point increases, the C2 reaches the thyristor (SCR) trigger breakover threshold voltage (VSCR) during the forward charging time. The time TC2 + is also gradually longer. Thus, the overbreak time TSCR of the thyristor SCR is shortened, so that the charging time TC1 for the capacitor C1 is shortened, and the capacitor C1 is reduced. The voltage VC1 may also drop accordingly to achieve the protection purpose of the load.

In other words, the reverse charge time (TC2-) of the capacitor (C2) is reduced because the AC input load decreases, the reverse charge current decreases, and also delays the time passing through the constant voltage diode (TVS). And the capacitor C2 shortens the charging time and reduces the charging current, resulting in the formation of a low negative pressure VC2- at the point A, and thus the capacitor C2 is charged forward. In time, the time to reach the thyristor (SCR) trigger break over threshold voltage (VSCR) is shortened, thereby increasing the charging time (TC1) of the capacitor (Cac) (C1), the voltage (VC1) of the capacitor (Cac) (C1) ) Also rises accordingly to ensure voltage stability on capacitor C1.

Generally, of AC input voltage Since the voltage values of the positive negative half cycle are the same and are within the AC input negative half cycle frequency, the resistor R1 in the first control circuit remains active. Therefore, the reverse charging current of the capacitor C2 is greater than the forward charging current of the capacitor C2 in the AC input positive half cycle frequency, and among the first control circuit and the second control circuit, By selecting the appropriate component parameter, when the AC input voltage exceeds the specified safety voltage (e.g. greater than 320 AC), the voltage at point A is within the positive half cycle of the AC input. The thyristor threshold voltage cannot be reached, the thyristor does not break over, and the disconnected power is input to the circuit to protect the safety of the load.

The first and second control circuits realize phasing control and automatic chopper suppression for AC input power, and break over at least one positive half cycle when the pressure suddenly rises. Only one positive half-cycle voltage, the capacitor (C1) and the load can often be completely extinguished, but not enough to damage the circuit components, it can be said to ensure the safety of the load completely .

Embodiment 2: As shown in Fig. 7, a single phase half wave overvoltage protection expansion circuit is provided, wherein the circuit structure and the single phase half wave overvoltage protection basic circuit structure of the first embodiment basically coincide, but the circuit also One diode (D3), the cathode of the diode (D3) and the resistor (R3) is connected in series with each other, the cathode and the resistor (R3) is connected to each other, the anode and the common ground is connected to each other have. Comparing Example 1 with the circuit, when the AC input is at the start of the positive half cycle, the input positive half cycle voltage is greater than the voltage on the capacitor C1. Only when the first control circuit starts the forward charging process for the capacitor (C2), delay the forward charging time for the capacitor (C2), shortening the break-over time of the thyristor (SCR) As a result, the charging time of the capacitor C1 is reduced, and as the voltage of the capacitor C1 falls, the protection of the load is caused.

Resistor R3 does not work because of the reverse blocking of diode D3; In the AC input negative half cycle frequency, the diode D3 is in the forward state, and the second control circuit is the same as in the reverse charging situation of the first embodiment of the capacitor C2.

Embodiment 3 As shown in FIG. 8, the present invention also provides a single wave full wave overvoltage protection basic circuit. The circuit structure is connected to a second overvoltage protection circuit between a circuit basic phase of the second embodiment, an AC input and a load, and the single phase second overvoltage protection circuit 2 includes a thyristor (SCR.1) and a constant voltage diode (Zener). Diode (TVS.1), resistor (R1.1), resistor (R2.1), resistor (R3.1), diode (D1.1), diode (D2.1), diode (D3.1) and And a capacitor C2.1, and the anode and the common ground of the thyristor SCR. 1 are connected to each other, and the cathode is connected in series with the thyristor SCR. 1) and then connected to the load terminal, the anode of the Zener Diode (TVS.1) and the gate of the thyristor (SCR.1) are connected to each other, and the Zener Diode The cathodes of (TVS.1) are connected on a resistor (R1.1) and a resistor (R2.1) which are connected in parallel with each other. The rotor (R1.1) is directly connected to the common ground, and the resistor (R2.1) is connected to the diode (D2, 1) installed in the same direction as the Zener Diode (TVS.1). The capacitor (C2.1) is connected between the common ground and the capacitor (C2.1) between the cathode of the thyristor (SCR.1) and the anode of the constant voltage diode (TVS.1), and the resistor (R3.1) The diodes D3 and 1 are connected in series and are installed between the anodes of the diodes D1 and 1 and the AC input terminal. The cathodes of the diodes D3 and 1 and the diodes D3 and 1 are connected to each other. The AC input terminals are connected to each other.

The operating principle is the same as that of the first embodiment. In the first and second embodiments, only the charging of the capacitor C1 proceeds only during the AC input positive half cycle, and the capacitor during the AC input negative half cycle. Charging for (C1) does not proceed.

In the present embodiment, charging of the capacitor C1 may be performed in both the positive and negative half cycles of the AC input, thereby improving voltage stability on the capacitor C1. Let's do it.

Embodiment 4 As shown in Fig. 9, the present invention also provides a single wave full wave overvoltage protection expansion circuit. The circuit comprises a first overvoltage protection circuit (1), wherein a third overvoltage protection circuit (3) is connected between the AC input terminal and the load ground terminal, and the third overvoltage protection circuit (3) is a thyristor (SCR). .1) includes a Zener Diode (TVS.1), a resistor (R1.1), a resistor (R2.1), a capacitor (C2.1) and a diode (D2.1). The anode and the load ground of the thyristor (SCR.1) are connected to each other, and the cathode and the AC input terminal are connected to each other, and the cathode and the thyristor (SCR.1) of the Zener Diode (TVS.1) are connected to each other. Gates of the gates are connected to each other, and the anodes of the Zener Diodes TVS.1 are connected to the resistors R1.1 and R2.1 that are connected in parallel with each other. , Resistor (R1.1) is directly connected to the load ground and resistor (R2.1) is constant voltage. It is connected to the diode (D2, 1) installed in the reverse direction of the Zener diode and then connected to the load ground. The capacitor (C2.1) is the thyristor (SCR.1) cathode and the constant voltage diode (Zener Diode). (TVS.1) It is connected between the cathodes.

In the first overvoltage protection circuit 1, a diode D3.1 is also provided, the anode and the common ground of the diodes D3, 1 are connected to each other, and the cathode and the load terminal are connected to each other. In addition, a diode (D3) is installed, the diode (D3) is connected on the common ground and the load ground cable, the anode of the diode (D3) and the capacitor (C1) cathode is connected to each other, the diode The cathode of D3 and the anode of diode D3.1 in the first overvoltage protection circuit are connected to each other. Comparing the circuit and the single-phase full-wave overvoltage protection basic circuit in Example 3, the resistors R3 and R3.1 are used using the symmetry of the AC input power positive negative half cycle. ), Diode (D1), diode (D1.1) elements are reduced, so that the single-phase full-wave overvoltage protection basic circuit functions, to simplify the circuit and lower the cost.

The specific embodiments described in the present invention are merely illustrative of the subject matter of the present invention. For those skilled in the art, specific embodiments of the present invention may be modified in various ways, supplemented, or in a similar manner, but should not depart from the subject matter or claims of the present invention.

Although the terminology such as thyristors (SCR), constant voltage diodes (Zener Diodes) (TVS), resistors (R1), capacitors (Cac), diodes (D1), etc. are used a lot, other terminology may be used. The possibility is also not ruled out. The use of some terminology is merely intended to more conveniently depict and describe the subject matter of the present invention and, if any limitation is added to the description of the present invention, is contrary to the subject matter of the present invention.

Claims (8)

A first overvoltage protection circuit is connected between the AC input and the load, and the first overvoltage protection circuit includes a thyristor, a constant voltage diode, a first register, a second resistor, and a second diode. A second capacitor (Capacitor), the anode and the AC input terminal of the thyristors are connected to each other, the cathode and the load terminal of the thyristors are connected to each other, the cathode and the gate of the thyristor (Zener Diode) Gates are connected to each other, and anodes of the Zener Diodes are connected to the first resistor and the second resistor which are connected in parallel with each other, and the first resistor is directly connected to the AC input terminal. And the second resistor is connected to the reverse side of the constant voltage diode. After being connected to the anode, the AC input terminal is connected to each other, and the second capacitor is connected between the thyristor cathode and the constant voltage diode (Zener Diode) cathode, and between the load input terminal and the load ground terminal, the first capacitor ( Capacitor) is connected to the switch power frequency overvoltage protection circuit. The method of claim 1,
And a first diode connected between the thyristor cathode and the load terminal in the same direction as the thyristor. The method of claim 2,
And a third resistor is connected between the first diode anode and the common ground terminal. The method of claim 3, wherein
The switch power frequency overvoltage protection circuit includes a third diode, the cathode of the third diode and the third resistor are connected in series, the cathode of the third diode and the third resistor are connected to each other. And the anode and the common ground terminal of the third diode are connected to each other. The method of claim 4, wherein
A second overvoltage protection circuit is connected between the AC input and the load, and the single phase second overvoltage protection circuit includes a thyristor, a Zener diode, a first resistor, a second resistor, a third resistor, and a first diode. And a second diode, a third diode, and a second capacitor, wherein the anode and the common ground of the thyristor are connected to each other, and the cathode of the thyristor is connected in series in the same direction as the thyristor. The first terminal is connected to the load terminal through a diode, the anode of the zener diode and the gate of the thyristor are connected to each other, and the cathode of the zener diode is connected to each other in parallel. Is coupled on a first register and the second register, the first register being directly in common And the second resistor is connected to the second diode, which is installed in the same direction as the constant voltage diode, and then to the common ground, and the second capacitor is connected to the second capacitor. It is connected between a thyristor cathode and the anode of the constant voltage diode (Zener Diode), the third resistor and the third diode is connected in series between the first diode anode and the AC input terminal, the cathode of the third diode And the third diode are connected to each other, and the anode of the third diode and the AC input terminal are connected to each other. The method of claim 1,
A third overvoltage protection circuit is connected between the AC input terminal and the load ground terminal, and the third overvoltage protection circuit includes the thyristor, the constant voltage diode, the first resistor, the second resistor, and the second resistor. A capacitor includes a capacitor and the second diode, and the anode of the thyristor and the load ground terminal are connected to each other, the cathode of the thyristor and the AC input terminal are connected to each other, and the cathode diode cathode And a gate of the thyristor are connected to each other, and anodes of the constant voltage diodes are connected to the first resistor and the second resistor which are connected in parallel with each other, and the first resistor is Is directly connected to the load ground and the second resistor is a constant voltage diode. (Zener Diode) is connected to the load ground terminal through the second diode installed in the reverse direction, the second capacitor (Capacitor) is connected between the thyristor cathode and the constant voltage diode (Zener Diode) cathode Switch power frequency overvoltage protection circuit. The method according to claim 6,
A third diode is installed in the first overvoltage protection circuit, and the anode and the common ground terminal of the third diode are connected to each other, and the cathode and the load terminal of the third diode are connected to each other. Frequency overvoltage protection circuit. The method of claim 7, wherein
The third diode is connected on the common ground and the load ground cable, the anode of the third diode and the cathode of the first capacitor are connected to each other, the cathode of the third diode and the first overvoltage protection. And a third diode anode in the circuit is connected to each other.

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