Distributed DC power supply system

Abstract

The utility model relates to the technical field of direct current power supply, and proposes a distributed direct current power supply system, including: a rectifier circuit, a charging circuit, a battery E1, a DC / DC circuit, a controller and an inverter; the input end of the rectifier circuit is connected to the power grid, the output end of the rectifier circuit is connected to the input end of the charging circuit, the output end of the charging circuit is connected to the battery E1, the control end of the charging circuit is connected to the controller, and the battery E1 is connected to the controller; the battery E1 is connected to the input end of the DC / DC circuit, and the DC / DC circuit is used to output a direct current voltage; the battery E1 is connected to the input end of the inverter, the output end of the inverter is connected to the load, and the controller is connected to the control end of the inverter. Through the above technical solution, the problem of the distributed direct current power supply system affecting the service life of the battery in the related technology is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of direct current power supplies, and in particular to a distributed direct current power supply system. Background Art

[0002] The key technologies of distributed DC power supply systems include DC converters, energy management systems, power electronic equipment, etc. With the development of power electronics technology, distributed DC power supply systems will play an increasingly important role in future power systems. They are mainly used in small switch stations and user terminals to provide reliable and uninterrupted working power for various secondary circuit components such as microcomputer protection devices, instruments, indicator lights, etc. The battery is an important component of the distributed DC power supply system. In the existing distributed DC power supply system, the battery is charged directly by turning on and off the switch, which will affect the service life of the battery. Utility Model Content

[0003] The utility model provides a distributed DC power supply system, which solves the problem in the related art that the distributed DC power supply system affects the service life of the battery.

[0004] The technical solution of the utility model is as follows:

[0005] A distributed DC power supply system, including: a rectifier circuit, a charging circuit, a battery E1, a DC / DC circuit, a controller and an inverter;

[0006] The input end of the rectifier circuit is connected to the power grid, the output end of the rectifier circuit is connected to the input end of the charging circuit, the output end of the charging circuit is connected to the battery E1, the control end of the charging circuit is connected to the controller, and the battery E1 is connected to the controller;

[0007] The storage battery E1 is connected to the input end of the DC / DC circuit, and the DC / DC circuit is used to output a direct current voltage;

[0008] The storage battery E1 is connected to the input end of the inverter, the output end of the inverter is connected to a load, and the controller is connected to the control end of the inverter.

[0009] Furthermore, the utility model also includes a heat dissipation circuit, which is electrically connected to the rectifier circuit and the battery E1 respectively.

[0010] Furthermore, the utility model also includes a protection circuit, which is electrically connected to the storage battery E1 and is used to control the connection between the storage battery E1 and the DC / DC circuit and the inverter.

[0011] Furthermore, the charging circuit in the present invention includes a diode D1, a first switch tube Q1, a second switch tube Q2 and a resistor R5;

[0012] The anode of the diode D1 is connected to the output end of the rectifier circuit, the cathode of the diode D1 is connected to the input end of the inverter, the cathode of the diode D1 is connected to the first end of the first switch tube Q1, the second end of the first switch tube Q1 is connected to the positive electrode of the battery E1, the negative electrode of the battery E1 is connected to the first end of the resistor R5, the second end of the resistor R5 is grounded, the control end of the first switch tube Q1 is connected to the first end of the second switch tube Q2, the second end of the second switch tube Q2 is grounded, and the control end of the second switch tube Q2 is connected to the controller.

[0013] Further, the heat dissipation circuit in the utility model includes a resistor R6, a voltage stabilizer U1, a thermistor NT1, a resistor R7, an operational amplifier U6, a resistor R8, a third switch tube Q5 and a fan U2;

[0014] The first end of the resistor R6 is connected to the first end of the first switch tube Q1, the second end of the resistor R6 is connected to the cathode of the voltage regulator U1, the anode of the voltage regulator U1 is grounded, the reference electrode of the voltage regulator U1 is connected to the non-inverting input terminal of the operational amplifier U6, the reference electrode of the voltage regulator U1 is connected to the first end of the resistor R7 through the thermistor NT1, the second end of the resistor R7 is grounded, the first end of the resistor R7 is connected to the inverting input terminal of the operational amplifier U6, the output terminal of the operational amplifier U6 is connected to the inverting input terminal of the operational amplifier U6 through the resistor R8, the output terminal of the operational amplifier U6 is connected to the control end of the third switch tube Q5, the first end of the third switch tube Q5 is connected to the first power supply terminal of the fan U2, and the second power supply terminal of the fan U2 is connected to the first end of the first switch tube Q1.

[0015] Furthermore, the protection circuit in the present invention includes a resistor R11, a resistor R12, a timer U3, a NOT gate U4, a fourth switch tube Q6 and a relay K1;

[0016] The first end of the resistor R11 is connected to the positive electrode of the battery E1, the second end of the resistor R11 is grounded through the resistor R12, the second end of the resistor R11 is connected to the low trigger end of the timer U3, the low trigger end of the timer U3 is connected to the high trigger end of the timer U3, the output end of the timer U3 is connected to the input end of the NOT gate U4, the output end of the NOT gate U4 is connected to the control end of the fourth switch tube Q6, the first end of the fourth switch tube Q6 is connected to a 12V power supply, the second end of the fourth switch tube Q6 is connected to the first power supply end of the relay K1, and the second power supply end of the relay K1 is grounded;

[0017] The first end of the first switch of the relay K1 is connected to the positive electrode of the battery E1, the second end of the first switch of the relay K1 is connected to the input end of the DC / DC circuit, the first end of the second switch of the relay K1 is connected to the first end of the first switch tube Q1, and the second end of the second switch of the relay K1 is connected to the input end of the inverter.

[0018] The working principle and beneficial effects of the utility model are:

[0019] In the utility model, when the power supply of the power grid is normal, the AC power provided by the power grid is directly connected to the load to supply power to the load. At the same time, the power grid voltage is stepped down, rectified and filtered after passing through the rectifier circuit, and the high-voltage AC power is converted into a DC signal. The DC signal output by the rectifier circuit is used to charge the battery E1. The battery E1 is connected to the controller, and the controller can detect the remaining voltage of the battery E1. When the voltage in the battery E1 is lower than the set value, the controller sends a control instruction to the charging circuit. When the charging circuit receives the control instruction sent by the controller, the DC voltage output by the rectifier circuit can charge the battery E1 through the charging circuit. When the power of the battery E1 exceeds the set value, the controller outputs a control instruction to the charging circuit again. At this time, the charging circuit disconnects the connection between the rectifier circuit and the battery E1, and the battery E1 stops charging. The battery E1 is used to power the DC / DC circuit. When working, the DC / DC circuit is used to convert the discharge voltage of the battery E1 into DC voltages of different amplitudes to provide a reliable DC operating power supply for circuit breakers, load switches, and protective devices. When the power grid is powered normally, the inverter does not work. When the power grid is out of power due to a fault, the controller sends a control instruction to the control end of the inverter, and the inverter starts working. At this time, the battery E1 supplies power to the load through the inverter. The inverter is used to convert the DC voltage output by the battery E1 into an AC voltage that is the same as the grid voltage to supply power to the load. In the utility model, the controller can detect the voltage of the battery E1, and then output different control signals corresponding to different charging stages of the battery E1 according to the size of the voltage of the battery E1, thereby improving the service life of the battery E1. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] Figure 1 A structural block diagram of a distributed DC power supply system provided by an embodiment of the present disclosure;

[0022] Figure 2 A partial circuit diagram of a distributed DC power supply system provided in one embodiment of the present disclosure. DETAILED DESCRIPTION

[0023] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0024] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, rather than to describe a specific order.

[0025] Example 1

[0026] like Figure 1 As shown, this embodiment proposes a distributed DC power supply system, a rectifier circuit, a charging circuit, a battery E1, a DC / DC circuit, a controller and an inverter; the input end of the rectifier circuit is connected to the power grid, the output end of the rectifier circuit is connected to the input end of the charging circuit, the output end of the charging circuit is connected to the battery E1, the control end of the charging circuit is connected to the controller, and the battery E1 is connected to the controller; the battery E1 is connected to the input end of the DC / DC circuit, and the DC / DC circuit is used to output a DC voltage; the battery E1 is connected to the input end of the inverter, the output end of the inverter is connected to the load, and the controller is connected to the control end of the inverter.

[0027] Distributed DC power supply is a power system structure that generates, transmits and distributes electricity in the form of DC in a decentralized manner. Unlike traditional centralized AC power systems, distributed DC power supply systems can generate and use electricity in various places, reducing energy losses during long-distance power transmission. This system can use a variety of energy sources, such as solar energy, wind energy, fuel cells, etc., to directly convert electrical energy into DC power for users. The distributed DC power supply system mentioned in this embodiment is applied to a switch cabinet, and the DC power generated by the distributed DC power supply system is used to provide reliable DC operating power for circuit breakers, load switches, and protective devices.

[0028] In this embodiment, when the power supply of the power grid is normal, the AC power provided by the power grid is directly connected to the load to supply power to the load. At the same time, the power grid voltage is stepped down, rectified and filtered after passing through the rectifier circuit, and the high-voltage AC power is converted into a 24V DC signal. The 24V DC signal output by the rectifier circuit is used to charge the battery E1. The battery E1 is connected to the controller, and the controller can detect the residual voltage of the battery E1. When the voltage in the battery E1 is lower than the set value, the controller sends a control instruction to the charging circuit. When the charging circuit receives the control instruction sent by the controller, the 24V DC voltage output by the rectifier circuit can charge the battery E1 through the charging circuit. When the power of the battery E1 exceeds the set value, the controller again outputs a control instruction to the charging circuit. At this time, the charging circuit disconnects the connection between the rectifier circuit and the battery E1, and the battery E1 stops charging.

[0029] The battery charging process can usually be divided into three stages: constant current charging stage, constant voltage charging stage and floating charging stage. The following are the details of these three stages:

[0030] Constant current charging stage: In the initial stage of the charging process, the charger charges the battery with a constant current. The main purpose of this stage is to quickly restore the battery voltage to a certain level. The constant current charging stage usually lasts until the battery voltage reaches a predetermined value, or the charging current drops to a certain value.

[0031] Constant voltage charging stage: The constant voltage charging stage follows the constant current charging stage. In this stage, the charger charges the battery at a constant voltage so that the battery capacity reaches 100% of the rated capacity. The charging speed in this stage depends on the internal resistance of the battery and the charging current. The constant voltage charging stage usually lasts until the charging current drops to a certain value.

[0032] Floating charging stage: The floating charging stage is the last stage of the charging process. In this stage, the charger charges the battery at a lower constant voltage to compensate for the power loss caused by the self-discharge of the battery. The floating charging stage can keep the battery power at 100% of the rated capacity for a long time. The charging voltage in this stage is usually slightly higher than the battery's termination charging voltage.

[0033] In this embodiment, the controller can detect the voltage of the battery E1, and then output different control signals corresponding to different charging stages of the battery E1 according to the voltage of the battery E1, thereby increasing the service life of the battery E1.

[0034] The battery E1 is used to power the DC / DC circuit. When working, the DC / DC circuit is used to convert the discharge voltage of the battery E1 into DC voltages of different amplitudes to provide reliable DC operating power for circuit breakers, load switches and protection devices.

[0035] When the power grid is supplying power normally, the inverter does not work. When the power grid is out of power due to a fault, the controller sends a control command to the control end of the inverter, and the inverter starts working. At this time, the battery E1 supplies power to the load through the inverter. The inverter is used to convert the DC voltage output by the battery E1 into an AC voltage the same as the grid voltage to supply power to the load.

[0036] like Figure 1 As shown, this embodiment also includes a heat dissipation circuit, which is electrically connected to the rectifier circuit and the battery E1 respectively.

[0037] During the operation of the distributed DC power supply system, the conversion of electric energy will generate heat. If this heat cannot be dissipated in time, it will cause the internal temperature of the power supply to rise, thereby affecting the performance and stability of the power supply, and may even cause damage to the power supply. To this end, a heat dissipation circuit is added in this embodiment, and the heat dissipation circuit is used to detect the temperature of the distributed DC power supply system. When the temperature exceeds the set value, the heat dissipation circuit cools the distributed DC power supply system. When the temperature of the distributed DC power supply system drops, the heat dissipation circuit automatically stops working.

[0038] like Figure 1 As shown, this embodiment also includes a protection circuit, which is electrically connected to the battery E1 and is used to control the connection between the battery E1 and the DC / DC circuit and the inverter.

[0039] During the use of battery E1, when the power is too low and lower than the minimum voltage required for its normal operation, the chemical reaction inside the battery will be unbalanced, causing the active material of the battery to fall off, thereby reducing the battery capacity and shortening the life. Multiple over-discharges will greatly reduce the battery capacity or even make it impossible to recover. After the battery is over-discharged, the chemical reaction inside the battery is unbalanced, making the recharging process difficult. Even if it can be charged, it will take a long time and the charging efficiency is low.

[0040] Therefore, a protection circuit is added in this embodiment to protect the storage battery E1 from over-discharge. When the power in the storage battery E1 is lower than a set value, the connection with the DC / DC circuit and the inverter is disconnected.

[0041] like Figure 2As shown, in this embodiment, the charging circuit includes a diode D1, a first switch tube Q1, a second switch tube Q2 and a resistor R5; the anode of the diode D1 is connected to the output end of the rectifier circuit, the cathode of the diode D1 is connected to the input end of the inverter, the cathode of the diode D1 is connected to the first end of the first switch tube Q1, the second end of the first switch tube Q1 is connected to the positive electrode of the battery E1, the negative electrode of the battery E1 is connected to the first end of the resistor R5, the second end of the resistor R5 is grounded, the control end of the first switch tube Q1 is connected to the first end of the second switch tube Q2, the second end of the second switch tube Q2 is grounded, and the control end of the second switch tube Q2 is connected to the controller.

[0042] In this embodiment, when the grid voltage is normal, the grid directly supplies power to the load, and the grid voltage outputs a 24V DC voltage after passing through the rectifier circuit. The resistor R5 is a sampling resistor. The controller is used to detect the voltage on the resistor R5, and outputs a PWM control signal according to the voltage on the resistor R5. The control signal is added to the control end of the second switch tube Q2. When the PWM control signal is at a high level, the second switch tube Q2 is turned off, the first switch tube Q1 is also turned off, and the battery E1 is not charged. When the PWM control signal is at a low level, the second switch tube Q2 is turned on, and the first switch tube Q1 is also turned on. At this time, the 24V DC power output by the rectifier circuit charges the battery E1 after passing through the first switch tube Q1. The controller can change the duty cycle of the PWM control signal according to the voltage on the resistor R5, thereby meeting the charging requirements of the battery E1 at different charging stages.

[0043] like Figure 2 As shown, the heat dissipation circuit in this embodiment includes a resistor R6, a voltage regulator U1, a thermistor NT1, a resistor R7, an operational amplifier U6, a resistor R8, a third switch tube Q5 and a fan U2; a first end of the resistor R6 is connected to a first end of the first switch tube Q1, a second end of the resistor R6 is connected to a cathode of the voltage regulator U1, an anode of the voltage regulator U1 is grounded, a reference electrode of the voltage regulator U1 is connected to a non-inverting input terminal of the operational amplifier U6, a reference electrode of the voltage regulator U1 is connected to a first end of the resistor R7 through the thermistor NT1, a second end of the resistor R7 is grounded, a first end of the resistor R7 is connected to an inverting input terminal of the operational amplifier U6, an output terminal of the operational amplifier U6 is connected to an inverting input terminal of the operational amplifier U6 through a resistor R8, an output terminal of the operational amplifier U6 is connected to a control terminal of the third switch tube Q5, a first end of the third switch tube Q5 is connected to a first power supply terminal of the fan U2, and a second power supply terminal of the fan U2 is connected to a first end of the first switch tube Q1.

[0044] In this embodiment, the heat dissipation circuit is used to detect the operating temperature of the distributed DC power supply system. When the operating temperature of the distributed DC power supply system exceeds the set value, the distributed DC power supply system is cooled. The working principle of the heat dissipation circuit is:

[0045] The resistor R6 and the voltage regulator U1 constitute a voltage source, which is used to provide a stable reference voltage for the in-phase input terminal of the operational amplifier U6, and at the same time provide a stable working voltage for the thermistor NT1. The thermistor NT1 is used to detect the working temperature of the distributed DC power supply system. The thermistor NT1 in this embodiment has a negative temperature coefficient. The higher the temperature, the smaller the resistance of the thermistor NT1, and vice versa. The thermistor NT1 and the resistor R7 constitute a voltage divider circuit. When the working temperature of the distributed DC power supply system is lower than the set value, the resistance of the thermistor NT1 is larger, and the voltage divider on the resistor R7 is smaller. The operational amplifier U6 constitutes an amplification circuit. At this time, the output voltage of the operational amplifier U6 is greater than the conduction voltage of the switch tube Q5. Therefore, the third switch tube Q5 is turned off and the fan U2 does not work. When the operating temperature of the distributed DC power supply system is higher than the set value, the resistance of thermistor NT1 decreases and the voltage divider on resistor R7 increases. At this time, the output voltage of op amp U6 is less than the turn-on voltage of switch tube Q5. Therefore, the third switch tube Q5 is turned on and fan U2 starts to cool the distributed DC power supply system until the temperature is lower than the set value.

[0046] like Figure 2 As shown, the protection circuit in this embodiment includes a resistor R11, a resistor R12, a timer U3, a NOT gate U4, a fourth switch tube Q6 and a relay K1; a first end of the resistor R11 is connected to the positive electrode of the battery E1, a second end of the resistor R11 is grounded through the resistor R12, a second end of the resistor R11 is connected to the low trigger end of the timer U3, the low trigger end of the timer U3 is connected to the high trigger end of the timer U3, an output end of the timer U3 is connected to the input end of the NOT gate U4, an output end of the NOT gate U4 is connected to the control end of the fourth switch tube Q6, a first end of the fourth switch tube Q6 is connected to a 12V power supply, a second end of the fourth switch tube Q6 is connected to a first power supply end of the relay K1, and a second power supply end of the relay K1 is grounded; a first end of the first switch of the relay K1 is connected to the positive electrode of the battery E1, a second end of the first switch of the relay K1 is connected to the input end of the DC / DC circuit, a first end of the second switch of the relay K1 is connected to the first end of the first switch tube Q1, and a second end of the second switch of the relay K1 is connected to the input end of the inverter.

[0047] In this embodiment, the protection circuit is used to provide over-discharge protection. When the power level of the battery E1 is lower than a set value, the connection with the DC / DC circuit and the inverter is disconnected. Specifically, the working principle of the protection circuit is as follows:

[0048] In this embodiment, the relay K1 includes two contact switches, and the first switch K1-1 of the relay K1 and the second switch K1-2 of the relay K1 are both normally closed switches. The first switch K1-1 of the relay K1 is used to control the connection between the battery E1 and the DC / DC circuit, and the first switch K1-2 of the relay K1 is used to control the connection between the battery E1 and the inverter. The timer U3 constitutes a trigger. When the voltage at the low trigger end of the timer U3 is higher than 1 / 3 of the power supply voltage of the timer U3, the timer U3 outputs a high level, otherwise, the timer U3 outputs a low level.

[0049] When the amount of electricity in the battery E1 is higher than the set value, the voltage on the resistor R12 is greater than 1.67V, and the timer U3 outputs a high level, which is converted to a low level after passing through the NOT gate U4, and the fourth switch tube Q6 is turned off, the coil of the relay K1 is not energized, and the first switch K1-1 of the relay K1 and the second switch K1-2 of the relay K1 do not operate. When the amount of electricity in the battery E1 is lower than the set value, the voltage on the resistor R12 is less than 1.67V, and the timer U3 outputs a low level, which is converted to a high level after passing through the NOT gate U4, and the fourth switch tube Q6 is turned on, the coil of the relay K1 is energized, and the first switch K1-1 of the relay K1 and the second switch K1-2 of the relay K1 are disconnected.

[0050] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A distributed DC power supply system, characterized in that: include: Rectification circuit, charging circuit, battery E1, DC / DC circuit, controller and inverter; The input end of the rectifier circuit is connected to the power grid, the output end of the rectifier circuit is connected to the input end of the charging circuit, the output end of the charging circuit is connected to the battery E1, the control end of the charging circuit is connected to the controller, and the battery E1 is connected to the controller; The storage battery E1 is connected to the input end of the DC / DC circuit, and the DC / DC circuit is used to output a direct current voltage; The battery E1 is connected to the input end of the inverter, the output end of the inverter is connected to a load, and the controller is connected to the control end of the inverter.

2. The distributed DC power supply system according to claim 1, characterized in that: It also includes a heat dissipation circuit, which is electrically connected to the rectifier circuit and the battery E1 respectively.

3. The distributed DC power supply system according to claim 2, characterized in that: The device further comprises a protection circuit, which is electrically connected to the storage battery E1 and is used to control the connection between the storage battery E1 and the DC / DC circuit and the inverter.

4. The distributed DC power supply system according to claim 3, characterized in that: The charging circuit includes a diode D1, a first switch tube Q1, a second switch tube Q2 and a resistor R5; The anode of the diode D1 is connected to the output end of the rectifier circuit, the cathode of the diode D1 is connected to the input end of the inverter, the cathode of the diode D1 is connected to the first end of the first switch tube Q1, the second end of the first switch tube Q1 is connected to the positive electrode of the battery E1, the negative electrode of the battery E1 is connected to the first end of the resistor R5, the second end of the resistor R5 is grounded, the control end of the first switch tube Q1 is connected to the first end of the second switch tube Q2, the second end of the second switch tube Q2 is grounded, and the control end of the second switch tube Q2 is connected to the controller.

5. The distributed DC power supply system according to claim 4, characterized in that: The heat dissipation circuit includes a resistor R6, a voltage stabilizer U1, a thermistor NT1, a resistor R7, an operational amplifier U6, a resistor R8, a third switch tube Q5 and a fan U2; The first end of the resistor R6 is connected to the first end of the first switch tube Q1, the second end of the resistor R6 is connected to the cathode of the voltage regulator U1, the anode of the voltage regulator U1 is grounded, the reference electrode of the voltage regulator U1 is connected to the non-inverting input terminal of the operational amplifier U6, the reference electrode of the voltage regulator U1 is connected to the first end of the resistor R7 through the thermistor NT1, the second end of the resistor R7 is grounded, the first end of the resistor R7 is connected to the inverting input terminal of the operational amplifier U6, the output terminal of the operational amplifier U6 is connected to the inverting input terminal of the operational amplifier U6 through the resistor R8, the output terminal of the operational amplifier U6 is connected to the control end of the third switch tube Q5, the first end of the third switch tube Q5 is connected to the first power supply terminal of the fan U2, and the second power supply terminal of the fan U2 is connected to the first end of the first switch tube Q1.

6. The distributed DC power supply system according to claim 4, characterized in that: The protection circuit includes a resistor R11, a resistor R12, a timer U3, a NOT gate U4, a fourth switch tube Q6 and a relay K1; The first end of the resistor R11 is connected to the positive electrode of the battery E1, the second end of the resistor R11 is grounded through the resistor R12, the second end of the resistor R11 is connected to the low trigger end of the timer U3, the low trigger end of the timer U3 is connected to the high trigger end of the timer U3, the output end of the timer U3 is connected to the input end of the NOT gate U4, the output end of the NOT gate U4 is connected to the control end of the fourth switch tube Q6, the first end of the fourth switch tube Q6 is connected to a 12V power supply, the second end of the fourth switch tube Q6 is connected to the first power supply end of the relay K1, and the second power supply end of the relay K1 is grounded; The first end of the first switch of the relay K1 is connected to the positive electrode of the battery E1, the second end of the first switch of the relay K1 is connected to the input end of the DC / DC circuit, the first end of the second switch of the relay K1 is connected to the first end of the first switch tube Q1, and the second end of the second switch of the relay K1 is connected to the input end of the inverter.

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