A non-isolated low voltage control high voltage line switch circuit

Abstract

The application relates to the field of circuit control, in particular to a non-isolated low-voltage control high-voltage line switch circuit which comprises a low-voltage trigger signal generation unit, a drive control unit, a high-voltage switch unit and a soft start control unit. The low-voltage trigger signal generation unit generates a low-voltage control signal, the drive control unit receives the low-voltage trigger signal and charges the gate of a switch tube, the high-voltage switch unit controls the on-off of a high-voltage line and buffers current limiting, and the soft start control unit controls the conduction and cut-off of a triode through a charge-discharge capacitor, adjusts the voltage of a voltage division node to realize the soft start of the switch tube. The application achieves the technical effects of controlling the high-voltage line switch with a low-voltage signal, suppressing contact arc and impact current, and avoiding reverse current and power reverse connection impact.

Description

Technical Field

[0001] This application relates to the field of circuit control, and in particular to a non-isolated low-voltage control high-voltage line switching circuit. Background Technology

[0002] In the field of electronics, switching circuits are widely used, especially in switching power supply products requiring remote control, such as industrial control equipment, intelligent power management for home appliances, and power control systems for data centers. Switching circuits play a crucial role in these applications, affecting not only the normal operation of the equipment but also the stability and security of the entire system. With the continuous development of technology, the performance requirements for switching circuits are becoming increasingly stringent, making the efficient and stable control of circuit continuity a key research focus.

[0003] In the past, two main methods were used to control the on / off state of circuits. One was push-button switch control, a mechanical switch that uses physical buttons to turn the circuit on and off. This method was highly reliable and had strong anti-interference capabilities. The other was electronic switch control, which uses electronic components (such as transistors) to build the switching circuit, enabling remote, real-time, or intelligent control.

[0004] However, existing technologies have significant drawbacks. Push-button switch control is only suitable for low-voltage circuits and not for high-voltage circuits. In high-voltage circuits, the instantaneous activation of a push-button switch generates arcing (electric discharge), leading to contact oxidation and poor contact. Long-term use reduces reliability and prevents remote control, limiting flexibility. Electronic switch control suffers from poor stability; the switching transistor is prone to failure or breakdown, especially under high-voltage surge impacts, which can easily cause false triggering. Utility Model Content

[0005] The purpose of this application is to overcome the above-mentioned technical problems and provide a non-isolated low-voltage control high-voltage line switching circuit.

[0006] A non-isolated low-voltage controlled high-voltage line switching circuit, comprising:

[0007] A low-voltage trigger signal generation unit is used to generate a low-voltage trigger signal based on the voltage division of the high-voltage input terminal. The low-voltage trigger signal generation unit includes a mechanical push-button switch, a voltage divider resistor network, and an arc-suppressing capacitor. The voltage divider resistor network is connected in series with the mechanical push-button switch and then connected to the positive terminal of the high-voltage input terminal. The arc-suppressing capacitor is connected in parallel across the two ends of the mechanical push-button switch to suppress the contact arc.

[0008] The drive control unit has its input terminal connected to the output terminal of the low-voltage trigger signal generation unit. It receives the low-voltage trigger signal from the low-voltage trigger signal generation unit and connects it in series with the gate of the switching transistor via a sixth resistor and a first diode to charge the gate of the switching transistor. The drive control unit also includes a voltage divider node, which is the connection point between the sixth and ninth resistors, and is used to connect to the soft-start control unit. Furthermore, the drive control unit includes a Zener diode connected in parallel between the gate and source of the switching transistor to limit the drive level amplitude.

[0009] The soft-start control unit includes a charging and discharging capacitor, a transistor, and a resistor assembly. The input terminal of the soft-start control unit is connected to the output terminal of the low-voltage trigger signal generation unit to receive the low-voltage trigger signal. The soft-start control unit controls the conduction and cutoff of the transistor through the charging and discharging process of the charging and discharging capacitor to adjust the voltage divider node voltage of the drive control unit, thereby realizing the soft start of the switching transistor and suppressing the inrush current.

[0010] A high-voltage switching unit includes a switching transistor and a first current-limiting resistor. The source of the switching transistor is directly connected to the negative terminal of the high-voltage input, the drain is connected to the negative terminal of the load through the first current-limiting resistor, and the gate receives a control signal through the drive control unit. The first current-limiting resistor is used to buffer and limit the current at the moment of turn-on to suppress surge impact.

[0011] By adopting the above technical solutions, the safe and reliable application of button control in high-voltage lines is achieved. This avoids the arc discharge phenomenon that occurs during the switching of traditional mechanical buttons at high voltage, reduces the risk of contact oxidation and poor contact, and improves the long-term reliability of switch control in high-voltage scenarios. It breaks through the limitation that traditional buttons can only be used in low-voltage lines, enabling direct control of high-voltage lines without relying on complex high-voltage isolation conversion structures, thus expanding the applicability of button switches. It enhances the surge resistance of switching transistors in high-voltage environments, reducing the risk of failure or breakdown due to high-voltage impacts, extending the service life of electronic switches, and reducing maintenance costs. It eliminates the need for additional drive circuits and independent power supply modules, simplifying the overall circuit design, reducing system complexity, and decreasing the number of components and power requirements, directly reducing production and application costs, and improving circuit integration and practicality. It also balances control flexibility, retaining the advantages of remote control and intelligent adjustment of electronic switches while addressing the above issues, achieving a balance between reliability and flexibility in high-voltage control.

[0012] Preferably, the voltage divider resistor network includes a first resistor, a second resistor, a third resistor, and a fourth resistor connected in series; one end of the first resistor is connected to the positive terminal of the high voltage input, and the other end is connected in series with the second resistor; the other end of the second resistor is connected together with the fourth resistor and one end of the arc-suppressing capacitor; the other end of the fourth resistor is connected in series with the mechanical push-button switch and the third resistor, and then connected to the other end of the arc-suppressing capacitor to form a closed voltage divider circuit.

[0013] By adopting the above technical solution, a voltage divider resistor network is formed by the first, second, third, and fourth resistors connected in series. This network is connected in series with the mechanical push-button switch and then connected to the positive terminal of the high-voltage input. This allows for the generation of a low-voltage trigger signal based on the voltage division at the high-voltage input terminal. The arc-suppressing capacitor connected in parallel across the mechanical push-button switch can suppress the contact arc, thereby generating a control signal safely and reliably in the high-voltage line. This avoids the arcing phenomenon that occurs when traditional push-button switches are used in high-voltage lines, and improves the reliability and safety of the control.

[0014] Preferably, the anode of the first diode is connected to the sixth resistor, and the cathode is connected to the gate of the switching transistor, in order to prevent the reverse current of the gate of the switching transistor from flowing to the forward circuit through the sixth resistor.

[0015] By adopting the above technical solution, the reverse current of the gate of the switching transistor can be prevented from flowing to the front-stage circuit through the sixth resistor, thus ensuring the stable operation of the front-stage circuit and improving the reliability of the entire switching circuit.

[0016] Preferably, the drive control unit further includes: a filter capacitor connected in parallel between the gate and source of the switching transistor to absorb high-frequency interference spike voltage; and a ninth resistor connected in parallel between the gate and source of the switching transistor to release residual voltage and electrostatic charge at the gate and source of the switching transistor.

[0017] By adopting the above technical solution, the switching transistor's ability to resist high-frequency interference under high-voltage environment is improved, avoiding the breakdown of the switching transistor due to high-frequency interference peak voltage. At the same time, it can release the residual voltage and electrostatic charge at the gate and source of the switching transistor, reduce the risk of false turn-on of the switching transistor, and further improve the stability and reliability of the switching transistor.

[0018] Preferably, a fifth resistor is also included, which is connected in series between the output of the voltage divider resistor network and the input of the soft-start control unit and the input of the drive control unit, forming a common current-limiting path for the transmission of the low-voltage trigger signal to the two units.

[0019] By adopting the above technical solution, a fifth resistor is connected in series between the output of the voltage divider network and the input of the soft-start control unit and the drive control unit to form a common current-limiting path for the transmission of low-voltage trigger signals. This avoids damage to the two units caused by excessively large low-voltage trigger signals and improves the safety and stability of the circuit.

[0020] Preferably, the soft-start control unit further includes a seventh resistor, and the soft-start time is determined by the time constant of the charging / discharging capacitor and the seventh resistor. The time constant τ = the resistance value of the seventh resistor × the capacitance value of the charging / discharging capacitor, and the charging voltage of the charging / discharging capacitor reaches the base conduction voltage of the transistor as the charging threshold.

[0021] By adopting the above technical solution, the slow-start time of the switching transistor can be precisely controlled, so that the inrush current is suppressed within a suitable time, further enhancing the surge resistance of the switching transistor under high voltage environment and reducing the risk of failure or breakdown caused by high voltage impact.

[0022] Preferably, the base of the transistor is connected to the charging / discharging capacitor, the emitter is connected to the voltage divider node of the drive control unit through the eighth resistor, and the collector is connected to the negative terminal of the high-voltage input.

[0023] By adopting the above technical solution, the charging and discharging process of the charging and discharging capacitor can be used to control the conduction and cutoff of the transistor, thereby adjusting the voltage of the voltage divider node of the drive control unit, realizing the soft start of the switching transistor, suppressing the inrush current, enhancing the surge resistance of the switching transistor in a high-voltage environment, and reducing the risk of failure or breakdown caused by high-voltage impact.

[0024] Preferably, when the transistor is turned on, the eighth resistor and the ninth resistor are connected in parallel to form an equivalent resistance Req = (R8 × R9) / (R8 + R9), and the voltage divider node voltage satisfies: Vdiv = Vin_drv × Req / (R6 + Req); when the transistor is turned off, an open circuit is formed between the eighth resistor and the ninth resistor, and the voltage divider node voltage satisfies: Vdiv = Vin_drv × R9 / (R6 + R9); where: Vin is the voltage of the high-voltage input terminal, Vin_drv is the voltage obtained after the high-voltage input terminal voltage is divided by the voltage divider resistor network of the low-voltage trigger signal generation unit, and Vth is the threshold turn-on voltage of the switching transistor.

[0025] By adopting the above technical solution, the voltage of the voltage divider node can be flexibly adjusted according to the conduction and cutoff states of the transistor, thereby accurately controlling the switching transistor and achieving stable and reliable control of the high-voltage line, enhancing the working stability and reliability of the switching transistor in a high-voltage environment.

[0026] Preferably, the soft-start control unit further includes a second diode, the cathode of which is connected to the positive terminal of the charging and discharging capacitor and the anode of which is connected to the negative terminal of the high-voltage input terminal, to prevent the charging and discharging capacitor from reversing and the power supply from being reversed.

[0027] By adopting the above technical solution, the impact on the circuit caused by reverse discharge of the charging and discharging capacitor and reverse power connection is avoided, further ensuring the normal operation of the soft start control unit and the stability of the circuit.

[0028] Preferably, the DC voltage at the high-voltage input terminal is 250V, the switching transistor is a voltage-controlled switching transistor with a withstand voltage of not less than 300V, and the on / off control is achieved through the gate voltage signal.

[0029] By adopting the above technical solution, the switching transistor can operate stably in a DC circuit with a 250V high voltage input, avoiding problems such as breakdown due to insufficient withstand voltage, ensuring the safety and reliability of the circuit, and the switching transistor can be conveniently controlled by the gate voltage signal, improving the convenience of control.

[0030] In summary, this application includes at least one of the following beneficial technical effects:

[0031] 1. It realizes the safe and reliable application of button control in high-voltage lines, avoids the arc discharge phenomenon of traditional mechanical buttons at the moment of high voltage switching, reduces the risk of contact oxidation and poor contact, and improves the long-term reliability of switch control in high-voltage scenarios;

[0032] 2. It breaks through the limitation that traditional buttons can only be used in low-voltage circuits, and can directly control high-voltage circuits without relying on complex high-voltage isolation conversion structures, thus expanding the application range of button switches;

[0033] 3. It improves the surge resistance of the switching transistor under high voltage environment, reduces the risk of failure or breakdown caused by high voltage impact, extends the service life of electronic switches, and reduces maintenance costs.

[0034] 4. It retains the advantages of remote control and intelligent adjustment of electronic switches, achieving a balance between reliability and flexibility in high-voltage control. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a non-isolated low-voltage control high-voltage switching circuit provided in an embodiment of this application;

[0036] Figure 2 This is a circuit diagram of the first non-isolated low-voltage control high-voltage switch circuit provided in the embodiments of this application;

[0037] Explanation of reference numerals in the attached diagram: 1. Low-voltage trigger signal generation unit; 2. Drive control unit; 3. Soft-start control unit; 4. High-voltage switching unit; S1. Mechanical push-button switch; R1. First resistor; R2. Second resistor; R3. Third resistor; R4. Fourth resistor; R5. Fifth resistor; R6. Sixth resistor; R7. Seventh resistor; R8. Eighth resistor; R9. Ninth resistor; R11. First current-limiting resistor; C1. Filter capacitor; C2. Charging and discharging capacitor; C3. Arc-suppressing capacitor; D1. First diode; D3. Second diode; ZD1. Zener diode; Q1. Switching transistor; Q2. Transistor. Detailed Implementation

[0038] The following will be combined with the appendix Figure 1-2 The technical solutions in the embodiments of this utility model are described in further detail below. The described embodiments are only possible technical implementations of this utility model, but are not limited thereto. Other embodiments obtained by those skilled in the art in conjunction with the embodiments of this utility model without creative effort are also within the protection scope of this utility model.

[0039] Please refer to Figure 1-2 The non-isolated low-voltage control high-voltage switching circuit includes a low-voltage trigger signal generation unit 1, a drive control unit 2, a soft-start control unit 3, and a high-voltage switching unit 4.

[0040] This application mainly adopts a non-isolated low-voltage control high-voltage line switching circuit, which achieves the safe and reliable application of button control in high-voltage lines, and improves the stability of the switching transistor Q1, simplifies the circuit structure and reduces costs. The following is a further detailed description of this application.

[0041] The non-isolated low-voltage controlled high-voltage line switching circuit provided in this application includes a low-voltage trigger signal generation unit, a drive control unit, a soft-start control unit, and a high-voltage switching unit. The low-voltage trigger signal generation unit generates a low-voltage trigger signal based on a voltage divider of the high-voltage input terminal. The drive control unit receives the low-voltage trigger signal and charges the gate of the switching transistor Q1. The soft-start control unit controls the conduction and cutoff of the transistor Q2 through the charging and discharging process of the charging and discharging capacitor C2, adjusting the voltage divider node voltage of the drive control unit to achieve a soft start of the switching transistor Q1 and suppress inrush current. The switching transistor Q1 of the high-voltage switching unit switches the high-voltage line on and off according to the control signal from the drive control unit. This combination avoids the arc discharge phenomenon of traditional mechanical buttons at the moment of high-voltage switching, improves the surge resistance of the switching transistor Q1 in a high-voltage environment, and simplifies the circuit structure and reduces costs. This is because the low-voltage trigger signal generation unit avoids direct contact between the mechanical button and the high voltage, the arc-suppressing capacitor C3 suppresses the contact arc, the drive control unit rationally controls the gate charging of the switching transistor Q1, the soft-start control unit suppresses the inrush current, and the first current-limiting resistor R11 of the high-voltage switching unit suppresses surge impact.

[0042] Specifically, the low-voltage trigger signal generation unit includes a mechanical push-button switch S1, a voltage divider resistor network, and an arc-suppressing capacitor C3.

[0043] The mechanical push-button switch S1 is a key component in the manual operation control circuit. It typically uses a durable plastic shell to enclose metal contacts, usually made of copper alloy to ensure good conductivity and insulation. An alternative is a mechanical push-button switch S1 with a ceramic shell, as ceramic offers better high-temperature resistance and insulation. The voltage divider resistor network consists of four resistors connected in series: a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. One end of the first resistor R1 is connected to the positive terminal of the high-voltage input, and the other end is connected in series with the second resistor R2. The other end of the second resistor R2 is connected to the fourth resistor R4 and one end of the arc-suppression capacitor C3. The other end of the fourth resistor R4 is connected in series with the mechanical push-button switch S1 and the third resistor R3, and then connected to the other end of the arc-suppression capacitor C3, forming a closed voltage divider circuit. These resistors are generally metal film resistors, characterized by high precision and good stability. An alternative is a carbon film resistor, which is relatively cheaper. The arc-suppression capacitor C3 is connected in parallel across the mechanical push-button switch S1 to suppress contact arcing; a ceramic capacitor is typically chosen because of its good high-frequency characteristics and small size. Replaceable features include the use of mica capacitors, which offer higher insulation resistance and stability. The arc-suppression capacitor C3 is directly soldered to the two pins of the mechanical push-button switch S1 to ensure a good electrical connection.

[0044] When the mechanical push button switch S1 is pressed, the voltage at the high voltage input terminal is divided by the voltage divider resistor network to obtain a low voltage trigger signal. The arc suppression capacitor C3 suppresses the contact arc generated when the mechanical push button switch S1 is turned on and off, thus protecting the contacts of the mechanical push button switch S1.

[0045] Specifically, the input terminal of the drive control unit is connected to the output terminal of the low-voltage trigger signal generation unit to receive the low-voltage trigger signal from the low-voltage trigger signal generation unit, and is connected in series with the sixth resistor R6 and the first diode D1 to the gate of the switching transistor Q1 to charge the gate of the switching transistor Q1.

[0046] The sixth resistor, R6, is typically a metal film resistor. Its function is to limit the charging current and protect the gate of the switching transistor Q1. An alternative feature is a wire-wound resistor, which can withstand higher power. The anode of the first diode, D1, is connected to the sixth resistor R6, and the cathode is connected to the gate of the switching transistor Q1. This prevents reverse current from the gate of Q1 from flowing to the forward circuit through the sixth resistor R6. A fast recovery diode is usually chosen for its fast reverse recovery time. An alternative feature is a Schottky diode, which has a smaller forward voltage drop. The sixth resistor R6 and the first diode D1 are connected by soldering to ensure electrical connection stability. The drive control unit has a voltage divider node, which is the connection point between the sixth resistor R6 and the ninth resistor R9, used to connect to the soft-start control unit. The drive control unit also includes a Zener diode ZD1, a filter capacitor C1, and the ninth resistor R9. The Zener diode ZD1 is connected in parallel between the gate and source of the switching transistor Q1 to limit the drive level amplitude. A Zener diode is typically chosen for its stable breakdown voltage. Alternative features include the use of an avalanche diode, which offers better voltage regulation at high voltages. A filter capacitor C1 is connected in parallel between the gate and source of the switching transistor Q1 to absorb high-frequency interference spikes; a ceramic capacitor is typically used. Alternative features include the use of a polyester film capacitor, which has a larger capacitance. A ninth resistor R9 is connected in parallel between the gate and source of the switching transistor Q1 to release residual gate-source voltage and electrostatic charge; a metal film resistor is usually used.

[0047] After receiving the low-voltage trigger signal, the drive control unit charges the gate of the switch Q1 through the sixth resistor R6 and the first diode D1. The Zener diode ZD1 limits the drive level amplitude to prevent excessive voltage from breaking down the gate of the switch Q1. The filter capacitor C1 absorbs high-frequency interference spike voltage, and the ninth resistor R9 releases the residual voltage and electrostatic charge at the gate and source of the switch Q1.

[0048] Specifically, the soft-start control unit includes a charging / discharging capacitor C2, a transistor Q2, and a resistor assembly.

[0049] The charging / discharging capacitor C2 is typically an electrolytic capacitor, which has a large capacitance and can store a large amount of charge. An alternative is a tantalum capacitor, which has a smaller size and better stability. The base of transistor Q2 is connected to the charging / discharging capacitor C2, the emitter is connected to the voltage divider node of the drive control unit through the eighth resistor R8, and the collector is connected to the negative terminal of the high-voltage input. A PNP transistor Q2 is usually chosen. The resistor assembly includes the seventh resistor R7, which is typically a metal film resistor. An alternative is a carbon film resistor. The soft-start control unit also includes a second diode D3, whose cathode is connected to the positive terminal of the charging / discharging capacitor C2, and its anode is connected to the negative terminal of the high-voltage input. This diode is used to prevent reverse discharge of the charging / discharging capacitor C2 and reverse power supply surges. A common diode is typically chosen. An alternative is a Schottky diode.

[0050] When the button is pressed, current flows through the button switch start circuit to charge the charging capacitor C2. During the charging process, the BE terminal of transistor Q2 is in a forward bias saturation and conduction state. This is equivalent to the eighth resistor R8 being connected in parallel with the ninth resistor R9 through transistor Q2 to the negative terminal of the high-voltage input. Originally, the driving voltage was a voltage divider formed by the series connection of the sixth resistor R6 and the ninth resistor R9. However, due to the participation of the eighth resistor R8, the amplitude of the voltage divider is lower, insufficient to drive the switch Q1 to conduct. When the voltage of the charging capacitor C2 rises to a certain value, transistor Q2 exits saturation and enters amplification and cutoff. The eighth resistor R8 is left floating and does not participate in the voltage divider. At this time, the driving voltage normally drives the switch Q1 to turn on. The charging time constant of the charging capacitor C2 determines the soft-start time, keeping it within a reasonable control range. The second diode D3 prevents reverse discharge of the charging capacitor C2 and power supply reverse connection impact.

[0051] Specifically, the high-voltage switching unit includes a switching transistor Q1 and a first current-limiting resistor R11.

[0052] Switch Q1 is a voltage-controlled switch with a withstand voltage of at least 300V. Its on / off control is achieved via a gate voltage signal. A MOSFET is typically used due to its advantages of fast switching speed and low power loss. An alternative is an IGBT, which offers higher withstand voltage and greater current carrying capacity. The first current-limiting resistor R11 is used to buffer and limit current during turn-on to suppress surge impact. It is typically a wire-wound resistor capable of handling higher power. An alternative is a metal film resistor. The source of switch Q1 is directly connected to the negative terminal of the high-voltage input, and the drain is connected to the negative terminal of the load through the first current-limiting resistor R11. The gate receives control signals from the drive control unit.

[0053] When the gate of the switching transistor Q1 receives a suitable control signal, the switching transistor Q1 is turned on, and the voltage at the high voltage input terminal supplies power to the load through the first current-limiting resistor R11; when the gate control signal of the switching transistor Q1 disappears, the switching transistor Q1 is turned off, and the load stops receiving power. The first current-limiting resistor R11 acts as a buffer and current limiter at the moment the switching transistor Q1 is turned on, suppressing surge impact.

[0054] In addition, the circuit includes a fifth resistor R5, which is connected in series between the output of the voltage divider network and the input of the soft-start control unit and the drive control unit, forming a common current-limiting path for the low-voltage trigger signal to be transmitted to the two units. The fifth resistor R5 is generally a metal film resistor, but a carbon film resistor can be used as an alternative.

[0055] The implementation principle of this embodiment is as follows: The non-isolated low-voltage control high-voltage line switching circuit of this embodiment achieves the switching on and off of the high-voltage line by controlling the low-voltage signal. The low-voltage trigger signal generation unit generates a low-voltage trigger signal using a voltage divider resistor network and a mechanical push-button switch S1, avoiding direct contact between the mechanical button and the high voltage. The arc-suppressing capacitor C3 suppresses the contact arc. The drive control unit rationally controls the gate charging of the switching transistor Q1. The Zener diode ZD1, the filter capacitor C1, and the ninth resistor R9 protect the switching transistor Q1. The soft-start control unit adjusts the drive voltage through the charging and discharging capacitor C2 and the transistor Q2, realizing the soft start of the switching transistor Q1 and suppressing the inrush current. The switching transistor Q1 of the high-voltage switching unit realizes the switching on and off of the high-voltage line according to the signal from the drive control unit. The first current-limiting resistor R11 suppresses the surge impact. The fifth resistor R5 plays a current-limiting role. Compared with the prior art, this circuit avoids the arc discharge phenomenon of traditional mechanical buttons at the moment of high-voltage switching, improves the surge resistance of the switching transistor Q1 in the high-voltage environment, simplifies the circuit structure, reduces costs, and at the same time takes into account the flexibility of control.

[0056] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A non-isolated low-voltage control high-voltage line switching circuit, characterized in that, include: A low-voltage trigger signal generation unit is used to generate a low-voltage trigger signal based on the voltage division of the high-voltage input terminal. The low-voltage trigger signal generation unit includes a mechanical push-button switch, a voltage divider resistor network, and an arc-suppressing capacitor. The voltage divider resistor network is connected in series with the mechanical push-button switch and then connected to the positive terminal of the high-voltage input terminal. The arc-suppressing capacitor is connected in parallel across the two ends of the mechanical push-button switch to suppress the contact arc. The drive control unit has its input terminal connected to the output terminal of the low-voltage trigger signal generation unit. It receives the low-voltage trigger signal from the low-voltage trigger signal generation unit and connects it in series with the gate of the switching transistor via a sixth resistor and a first diode to charge the gate of the switching transistor. The drive control unit also includes a voltage divider node, which is the connection point between the sixth and ninth resistors, and is used to connect to the soft-start control unit. Furthermore, the drive control unit includes a Zener diode connected in parallel between the gate and source of the switching transistor to limit the drive level amplitude. The soft-start control unit includes a charging and discharging capacitor, a transistor, and a resistor assembly. The input terminal of the soft-start control unit is connected to the output terminal of the low-voltage trigger signal generation unit to receive the low-voltage trigger signal. The soft-start control unit controls the conduction and cutoff of the transistor through the charging and discharging process of the charging and discharging capacitor to adjust the voltage divider node voltage of the drive control unit, thereby realizing the soft start of the switching transistor and suppressing the inrush current. A high-voltage switching unit includes a switching transistor and a first current-limiting resistor. The source of the switching transistor is directly connected to the negative terminal of the high-voltage input, the drain is connected to the negative terminal of the load through the first current-limiting resistor, and the gate receives a control signal through the drive control unit. The first current-limiting resistor is used to buffer and limit the current at the moment of turn-on to suppress surge impact.

2. The non-isolated low-voltage control high-voltage line switching circuit according to claim 1, characterized in that, The voltage divider resistor network includes a first resistor, a second resistor, a third resistor, and a fourth resistor connected in series; One end of the first resistor is connected to the positive terminal of the high voltage input, and the other end is connected in series with the second resistor; the other end of the second resistor is connected together with the fourth resistor and one end of the arc-suppressing capacitor; the other end of the fourth resistor is connected in series with the mechanical push-button switch and the third resistor, and then connected to the other end of the arc-suppressing capacitor to form a closed voltage divider circuit.

3. The non-isolated low-voltage control high-voltage line switching circuit according to claim 1, characterized in that, The anode of the first diode is connected to the sixth resistor, and the cathode is connected to the gate of the switching transistor, in order to prevent the reverse current of the gate of the switching transistor from flowing to the forward circuit through the sixth resistor.

4. The non-isolated low-voltage control high-voltage line switching circuit according to claim 1, characterized in that, The drive control unit further includes: A filter capacitor is connected in parallel between the gate and source of the switching transistor to absorb high-frequency interference spike voltages. The ninth resistor is connected in parallel between the gate and source of the switching transistor to release the residual voltage and electrostatic charge at the gate and source of the switching transistor.

5. The non-isolated low-voltage control high-voltage line switching circuit according to claim 1, characterized in that, It also includes a fifth resistor, which is connected in series between the output of the voltage divider resistor network and the input of the soft-start control unit and the input of the drive control unit, forming a common current-limiting path for the transmission of the low-voltage trigger signal to the two units.

6. The non-isolated low-voltage control high-voltage line switching circuit according to claim 1, characterized in that, The soft-start control unit also includes a seventh resistor. The soft-start time is determined by the time constant of the charging / discharging capacitor and the seventh resistor. The time constant τ = the resistance value of the seventh resistor × the capacitance value of the charging / discharging capacitor. The charging threshold is the charging voltage of the charging / discharging capacitor reaching the base conduction voltage of the transistor.

7. The non-isolated low-voltage control high-voltage line switching circuit according to claim 1, characterized in that, The base of the transistor is connected to the charging and discharging capacitor, the emitter is connected to the voltage divider node of the drive control unit through the eighth resistor, and the collector is connected to the negative terminal of the high voltage input.

8. The non-isolated low-voltage control high-voltage line switching circuit according to claim 7, characterized in that: When the transistor is turned on, the eighth resistor and the ninth resistor are connected in parallel to form an equivalent resistance Req=(R8×R9) / (R8+R9). At this time, the voltage of the voltage divider node satisfies: Vdiv = Vin_drv × Req / (R6 + Req); When the transistor is turned off, an open circuit is formed between the eighth resistor and the ninth resistor, and the voltage divider node voltage satisfies: Vdiv = Vin_drv × R9 / (R6 + R9); Wherein: Vin is the voltage of the high-voltage input terminal, Vin_drv is the voltage obtained after the high-voltage input terminal voltage is divided by the voltage divider resistor network of the low-voltage trigger signal generation unit, and Vth is the threshold conduction voltage of the switching transistor.

9. The non-isolated low-voltage control high-voltage line switching circuit according to claim 1, characterized in that, The soft-start control unit also includes a second diode, whose cathode is connected to the positive terminal of the charging and discharging capacitor and whose anode is connected to the negative terminal of the high-voltage input terminal, in order to prevent the charging and discharging capacitor from reversing and the power supply from being reversed.

10. The non-isolated low-voltage controlled high-voltage line switching circuit according to claim 1, characterized in that, The DC voltage at the high-voltage input terminal is 250V, and the switching transistor is a voltage-controlled switching transistor with a withstand voltage of not less than 300V, and the on / off control is achieved through the gate voltage signal.

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