CN202586293U - A leakage protection circuit of vehicle-mounted inverter and a corresponding vehicle-mounted inverter - Google Patents

Abstract

The utility model relates to a leakage protection circuit of vehicle-mounted inverter and a corresponding vehicle-mounted inverter. The leakage protection circuit comprises an insulation resistance detecting circuit, a comparison circuit, and an output time-delay circuit. The insulation resistance detecting circuit is connected with the AC output end of a vehicle-mounted inverter to detect the resistance to ground of the AC output end, and outputs the detected insulation resistance signal to the comparison circuit. If the insulation resistance is less than a preset value, the comparison circuit outputs a defective insulation signal to the output time-delay circuit. If duration time of the defective insulation signal exceeds a preset time, the output time-delay circuit outputs a leakage protection signal to a microcontroller in order to stop outputting AC voltage. The leakage protection circuit detects the insulation resistance to ground of the AC output end, and outputs the leakage protection signal to a boost microcontroller and an inversion microcontroller to stop outputting AC voltage if the insulation resistance to ground is less than the preset value so as to further prevent an accident of electric shock, or the inverter is rapidly stopped outputting to effectively protect personnel when the accident of electric shock happens.

Description

Leakage protection circuit of a vehicle-mounted inverter and corresponding vehicle-mounted inverter

technical field

The utility model relates to the technical field of vehicle-mounted inverters, in particular to a leakage protection circuit of a vehicle-mounted inverter and a corresponding vehicle-mounted inverter.

Background technique

The block diagram of the existing vehicle-mounted inverter is shown in Figure 1, including a DC filter circuit 10, a DC/DC boost circuit 20, a DC/AC inverter circuit 30 and an AC filter circuit 40, and is used to generate PWM waves to control DC The step-up microcontroller 50 of the /DC boost circuit 20 and the inverter microcontroller 60 for generating PWM waves to control the DC/AC inverter circuit 30 . After the DC input, first pass through the DC filter circuit 10 to reduce ripple current and suppress electromagnetic interference, then pass through the DC/DC booster circuit 20 to convert DC12V or DC24V to high-voltage direct current, and then pass through the DC/AC inverter circuit 30 to convert the high-voltage direct current Form a square wave modulated by SPWM sine wave pulse width, and finally output a sine wave AC voltage of AC220V/50Hz or AC110V/60Hz through the AC filter circuit 40, such as outputting the AC voltage through the AC output terminals AC1 and AC2.

When the vehicle-mounted inverter is only equipped with a two-hole socket, only Class II electrical equipment is allowed to be connected and used. Since Class II electrical equipment adopts reinforced insulation, it is safe to use. However, for the convenience of users, when the vehicle-mounted inverter needs to be equipped with a three-hole socket, it allows Class I electrical equipment to be used. The metal casing of the equipment is connected, and safety regulations require that leakage protection devices must be used to prevent electric shock accidents. Therefore, the main disadvantage of the existing vehicle-mounted inverter is that there is no leakage protection circuit or device, and when the three-hole socket configuration is used, there is no leakage protection for the output AC voltage, which is unsafe to use.

Utility model content

The technical problem to be solved by the utility model is to provide a vehicle-mounted inverter corresponding to the leakage protection circuit of the vehicle-mounted inverter in view of the defect that the existing vehicle-mounted inverter lacks the leakage protection of the output AC voltage and has potential safety hazards.

The technical solution adopted by the utility model to solve the technical problem is: construct a leakage protection circuit of a vehicle-mounted inverter, the vehicle-mounted inverter includes a DC filter circuit, a DC/DC boost circuit, and a DC/AC inverter circuit and an AC filtering circuit, and a boost microcontroller for controlling a DC/DC boost circuit and an inverter microcontroller for controlling a DC/AC inverter circuit; the leakage protection circuit includes: an insulation resistance detection circuit, Comparator circuit and output delay circuit;

The input end of the insulation resistance detection circuit is connected to the AC output end of the vehicle inverter, the output end is connected to the input end of the comparison circuit, and the generated insulation resistance detection signal is sent to the comparison circuit; the comparison circuit The output terminal is connected to the input terminal of the output delay circuit, the comparison circuit receives the insulation resistance detection signal, and sends the poor insulation signal generated when the insulation resistance is lower than the preset threshold value to the output delay circuit; The output end of the output delay circuit is connected to the boost microcontroller, the output delay circuit receives the poor insulation signal, and the leakage protection signal generated after the duration exceeds the preset time is sent to the inverter The microcontroller stops the AC voltage output.

In the leakage protection circuit of the vehicle-mounted inverter according to the utility model, the output delay circuit is also connected with the boost microcontroller, and sends the leakage protection signal to the boost microcontroller Stop DC/DC boost conversion.

In the leakage protection circuit of the vehicle-mounted inverter according to the utility model, the boost microcontroller is also connected with a fault alarm circuit, which receives the leakage protection signal and outputs a fault alarm signal.

In the leakage protection circuit of the vehicle-mounted inverter according to the present invention, the leakage protection circuit further includes an input filter circuit connected between the insulation resistance detection circuit and the comparison circuit.

In the leakage protection circuit of the vehicle-mounted inverter according to the utility model, the comparison circuit further includes: a peak value comparison circuit and an average value comparison circuit connected in parallel, and the input terminals of the peak value comparison circuit and the average value comparison circuit are connected to the The output terminals of the input filter circuit are connected, and the output terminals are connected to the output delay circuit, and the poor insulation signal generated by the peak value comparison and the poor insulation signal generated by the average value comparison are respectively sent to the output delay circuit.

In the leakage protection circuit of the vehicle-mounted inverter according to the utility model, the input filter circuit includes a first operational amplifier U1A, a capacitor C4 and a resistor R24, and the positive input terminal of the first operational amplifier U1A is connected to the The output terminal of the insulation resistance detection circuit is connected, and grounded through the capacitor C4; the signal output terminal of the first operational amplifier U1A is short-circuited with the positive input terminal to form a voltage follower; the signal output of the first operational amplifier U1A The terminal is also grounded through the resistor R24 and serves as the output terminal of the input filter circuit.

In the leakage protection circuit of the vehicle-mounted inverter according to the utility model, the peak comparison circuit includes: a second operational amplifier U1B, a resistor R17, a resistor R10, a resistor R19, and a resistor R20; the second operational amplifier U1B The positive input end of the resistor R20 is connected to the output end of the input filter circuit, the resistors R10 and R19 are connected in series to divide the voltage between the working voltage and the ground, and the node between the resistors R10 and R19 is connected to The reverse input terminal of the second operational amplifier U1B; the signal output terminal of the second operational amplifier U1B is grounded through the resistor R17, and connected to the output delay circuit;

The average value comparison circuit includes: a third operational amplifier U1C, a resistor R18, a resistor R21, a resistor R22, a resistor R23 and a capacitor C3; the positive input terminal of the third operational amplifier U1C is connected to the input filter through a resistor R23 The output terminal of the circuit is grounded through the capacitor C3; the resistors R21 and R22 are connected in series to divide the voltage between the working voltage and the ground, and the node between the resistors R21 and R22 is connected to the reverse side of the third operational amplifier U1C input terminal; the signal output terminal of the third operational amplifier U1C is grounded through a resistor R18 and connected to an output delay circuit.

In the leakage protection circuit of the vehicle inverter according to the present invention, the output delay circuit includes a capacitor C2, a fourth operational amplifier U1D, a resistor R12, a resistor R13, a resistor R14, a resistor R15 and a resistor R16. Wherein, the output end of the peak value comparison circuit is connected to the capacitor C2 through the resistor R15, the output end of the average value comparison circuit is also connected to the same end of the capacitor C2 through the resistor R16, and the other end of the capacitor C2 is grounded, and connected to the fourth operational amplifier U1D The positive input terminal, the resistor R13 and the resistor R14 are connected in series between the working voltage and the ground for voltage division, and the node between the resistor R13 and the resistor R14 is connected to the reverse input terminal of the fourth operational amplifier U1D; The signal output terminal of the fourth operational amplifier U1D is grounded through the resistor R12, and serves as the output terminal of the output delay circuit.

The utility model also provides a vehicle-mounted inverter, which includes a DC filter circuit, a DC/DC boost circuit, a DC/AC inverter circuit and an AC filter circuit, and a boost micro for controlling the DC/DC boost circuit. A controller and an inverter microcontroller for controlling the DC/AC inverter circuit; the vehicle-mounted inverter also includes the above-mentioned leakage protection circuit of the vehicle-mounted inverter.

Implementing the leakage protection circuit of the vehicle-mounted inverter of the present invention and the vehicle-mounted inverter adopting the leakage protection circuit have the following beneficial effects: the utility model can measure the insulation resistance of the AC output terminal of the vehicle-mounted inverter by using an insulation resistance detection circuit. It detects and generates a bad insulation signal when it is lower than the preset threshold, and outputs a leakage protection signal after the signal lasts longer than the preset time to control the inverter microcontroller of the vehicle inverter to stop the AC voltage output, and then in the event of an electric shock In the event of an accident, quickly cut off the AC output of the inverter, so that the vehicle-mounted inverter product can prevent electric shock accidents and effectively protect the safety of users.

Description of drawings

The utility model will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is a module block diagram of an existing vehicle-mounted inverter;

Fig. 2 is the modular block diagram of the vehicle-mounted inverter implemented according to the leakage protection circuit of the vehicle-mounted inverter of the present utility model;

3 is a schematic diagram of an insulation resistance detection circuit in the leakage protection circuit of the vehicle-mounted inverter of FIG. 2;

FIG. 4 is a schematic diagram of other circuits in the leakage protection circuit of the vehicle-mounted inverter shown in FIG. 2 .

Detailed ways

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments.

The utility model provides a leakage protection circuit for the vehicle-mounted inverter, so as to ensure that the AC output of the vehicle-mounted inverter is quickly cut off when an electric shock accident occurs.

Please refer to FIG. 2 , which is a block diagram of a vehicle-mounted inverter implemented by the leakage protection circuit of the vehicle-mounted inverter according to the present invention. As shown in FIG. 2 , the leakage protection circuit 70 of the vehicle-mounted inverter provided by the utility model can perform leakage protection for the vehicle-mounted inverter. The vehicle-mounted inverter can include a DC filter circuit 10, a DC/DC boost circuit 20, a DC/AC inverter circuit 30 and an AC filter circuit 40 as shown in FIG. A boost microcontroller 50 and an inverter microcontroller 60 for controlling the DC/AC inverter circuit 30 . The leakage protection circuit 70 of the vehicle-mounted inverter provided by the utility model at least includes an insulation resistance detection circuit 71 , a comparison circuit 72 and an output delay circuit 73 .

Wherein, the input terminal of the insulation resistance detection circuit 71 is connected to the AC output terminals AC1 and AC2 of the vehicle-mounted inverter, and detects the insulation resistance of the AC output terminals AC1 and AC2 to ground to generate an insulation resistance detection signal.

The input terminal of the comparison circuit 72 is connected to the output terminal of the insulation resistance detection circuit 71, receives the insulation resistance detection signal generated by the insulation resistance detection circuit 71, and compares it with the preset threshold value, and when it is judged that the insulation resistance is less than the preset threshold value, it is considered that the insulation resistance is less than Safe value, thus generating poor insulation signal. Specifically, it is realized by judging the voltage of the insulation resistance detection signal, the smaller the insulation resistance is, the larger the generated voltage is. Therefore, a voltage limit is set, and when the voltage of the insulation resistance detection signal is higher than the set voltage limit, it is judged that the insulation resistance is less than a safe value, and a high-level signal indicating poor insulation is generated.

The input end of the output delay circuit 73 is connected to the output end of the comparison circuit 72, and is used to receive the poor insulation signal generated by the comparison circuit 72, and generate a leakage protection signal when the duration of the poor insulation signal exceeds a preset time, so as to prevent false positives. action. The time delay circuit 73 is at least connected with the inverter microcontroller 60 of the vehicle-mounted inverter, and the leakage protection signal is sent to the inverter microcontroller 60 to stop outputting the PWM signal, so the work of the DC/AC inverter circuit 30 is stopped, The AC output terminals AC1 and AC2 of the vehicle inverter will also stop outputting AC voltage. In this way, when the insulation on the AC side of the vehicle-mounted inverter is poor or an electric shock accident occurs, the vehicle-mounted inverter can quickly cut off the AC output, thereby protecting the safety of electricity users.

The output delay circuit 73 of the leakage protection circuit 70 in the utility model can also send the leakage protection signal to the inverter microcontroller 60 and the step-up microcontroller 50 at the same time, and the inverter microcontroller 60 will immediately receive the leakage protection signal. Stop the DC/AC inverter to stop the AC output quickly. The step-up microcontroller 50 immediately stops the DC/DC step-up conversion after receiving the leakage protection signal, thereby preventing the step-up microcontroller 50 from still working when the output of the AC voltage is stopped, increasing safety and reducing loss. The boost microcontroller 50 can be further connected with a fault alarm circuit, which receives the leakage protection signal and outputs a fault alarm signal to remind the user.

In the utility model, the leakage protection circuit 70 can further include an input filter circuit 74 connected between the insulation resistance detection circuit 71 and the comparison circuit 72, which is used to filter the insulation resistance detection signal collected by the insulation resistance detection circuit 71 to eliminate interference. .

The circuit principle of each functional circuit of the leakage protection circuit of the vehicle-mounted inverter of the present invention will be specifically introduced below. Please refer to Fig. 3 and Fig. 4, which are circuit schematic diagrams of the insulation resistance detection circuit and other circuits in Fig. 2, respectively.

As shown in FIG. 3 , the insulation resistance detection circuit 71 is connected to the AC output terminals AC1 and AC2 of the vehicle inverter. The AC output terminal AC1 is connected to the anode of the diode D1, the AC output terminal AC2 is connected to the anode of the diode D2, the cathodes of the diode D1 and the diode D2 are connected together, and are connected to the input of the vehicle inverter through multiple resistors, such as resistor R1-resistor R7 DC side common terminal. The DC side of the vehicle inverter refers to the primary side of the DC filter circuit 10 and the DC/DC boost circuit 20 , and the AC side refers to the DC/AC inverter circuit 30 and the AC filter circuit 40 . Both ends of the resistor R1 and the resistor R2 are connected in parallel with a voltage regulator tube ZD1. The node voltage VIR between the resistor R1 and the resistor R2 is the output insulation resistance detection signal. The insulation resistance of the AC output terminal AC1 to the ground is represented by R8, and the insulation resistance of the AC output terminal AC2 to the ground is represented by R9. When the insulation of the AC side to the ground is poor or an electric shock accident occurs, the resistance values of the resistors R8 and R9 decrease individually or simultaneously, the current flowing through the resistors R1-R7 increases, and the voltage value of the insulation resistance detection signal VIR increases.

In the example of the vehicle-mounted inverter of the present invention, the diode D1 and the diode D2 adopt transient voltage suppression diodes with a breakdown voltage of 400V, which can not only suppress the interference voltage, but also withstand the withstand voltage test during product production. If ordinary diodes are used for diode D1 and diode D2, the insulation monitoring and protection circuit also has the same function, but high-voltage diodes must be selected for the withstand voltage test of the product.

As shown in FIG. 4 , the input filter circuit 74 includes a first operational amplifier U1A, a capacitor C4, a resistor R11 and a resistor R24. The positive input terminal of the first operational amplifier U1A is connected to the output terminal of the insulation resistance detection circuit 71 through the resistor R11. And connect to ground through capacitor C4. The signal output terminal of the first operational amplifier U1A is grounded through the resistor R24 , and the output terminal is short-circuited with the forward input terminal to form a voltage follower as the output terminal of the input filter circuit 74 . The insulation resistance detection signal is filtered by the resistor R11 and the capacitor C4 , and then output to the comparison circuit 72 after being filtered by the first operational amplifier U1A.

The comparison circuit 72 further includes a peak value comparison circuit 721 and an average value comparison circuit 722 connected in parallel. The insulation resistance detection signal output by the filter circuit 74 is divided into two paths, which are respectively provided to the peak value comparison circuit 721 and the average value comparison circuit 722 . The peak comparison circuit 721 compares the insulation resistance detection signal, and generates an insulation failure signal and outputs it to the output delay circuit 73 when the peak value of the insulation resistance detection signal is judged to be higher than the set peak threshold voltage. Similarly, the average value comparison circuit 722 compares the average value of the insulation resistance detection signal, and generates an insulation failure signal to output to the output delay circuit 73 when the average value of the insulation resistance detection signal is judged to be higher than the set average value threshold voltage.

Specifically, the peak comparison circuit 721 includes a second operational amplifier U1B, a resistor R17 , a resistor R10 , a resistor R19 and a resistor R20 . Resistors R10 and R19 are connected in series to divide the operating voltage such as 5V and the ground, and the node between the resistors R10 and R19 is connected to the inverting input terminal of the second operational amplifier U1B as the peak threshold voltage for comparison. The positive input terminal of the second operational amplifier U1B is connected to the output terminal of the filter amplifier circuit 74 through the resistor R20, and the signal output terminal of the second operational amplifier U1B is grounded through the resistor R17. When the voltage of the positive input terminal of the second operational amplifier U1B is higher than the voltage of the negative input terminal, the signal output terminal of the second operational amplifier U1B outputs a high-level poor insulation signal to the output delay circuit 73 .

The average value comparison circuit 722 includes a third operational amplifier U1C, a resistor R18 , a resistor R21 , a resistor R22 , a resistor R23 and a capacitor C3 . Resistors R21 and R22 are connected in series to divide the operating voltage such as 5V and the ground, and the node between the resistors R21 and R22 is connected to the inverting input terminal of the third operational amplifier U1C as the average threshold voltage for comparison. The positive input terminal of the third operational amplifier U1C is connected to the output terminal of the filter amplifier circuit 74 through the resistor R23, and the positive input terminal of the third operational amplifier U1C is also grounded through the capacitor C3, and the signal output terminal of the third operational amplifier U1C is passed through Resistor R18 is grounded. The filtered insulation resistance detection signal charges the capacitor C3 through the resistor R23, so as to output the average value of the insulation resistance detection signal to the positive input terminal of the third operational amplifier U1C. When its voltage is higher than the reverse input terminal voltage, The signal output terminal of the third operational amplifier U1C outputs a high-level poor insulation signal to the output delay circuit 73 .

There may be only one of the AC output terminals AC1 and AC2 of the vehicle inverter, or both of them may have poor insulation to the ground at the same time. When only one path, such as AC1, has poor insulation to the ground, the resistance value of the insulation resistance R8 drops, and the other path, such as AC2, has good insulation to the ground, and the resistance value of the insulation resistance R9 is still infinite. A loop is formed to AC1 to generate a loop current; due to the open circuit of resistor R9, AC1 cannot pass through diode D1, resistors R1~R7 and resistor R9, and then forms a loop to AC2, and there is no loop current. At this time, the insulation resistance detection signal VIR is a sine wave and half wave rectified waveform. When AC1 and AC2 have poor insulation to the ground at the same time, when the resistance of the insulation resistance R8 and R9 drops, AC1 passes through the diode D1, resistors R1~R7, AC1 also passes through the resistor R8, and then passes through the resistor R9, and then to AC2 to form a loop, resulting in Loop current, while AC2 passes through diode D2, resistors R1~R7, AC2 also passes through resistor R9, then resistor R8, and then to AC1 to form a loop to generate loop current. At this time, the insulation resistance detection signal VIR is a sine wave full-wave rectification waveform. When AC1 and AC2 have poor insulation to the ground at the same time, even if the insulation resistance is the same as when only one line has poor insulation to the ground, due to the influence of parallel shunt, the amplitude of the insulation resistance detection signal VIR is greatly reduced and cannot reach the peak value. The threshold voltage set by the circuit 721 generates a high-level signal of poor insulation, but at this time the insulation resistance detection signal VIR is a sinusoidal full-wave rectified waveform, and the average value comparison circuit 722 can effectively detect and output a signal of poor insulation. It can be seen that no matter one or two faults occur in the vehicle-mounted inverter, the comparison circuit 72 composed of the peak value comparison circuit 721 and the average value comparison circuit 722 can effectively detect that the insulation resistance is less than the preset insulation resistance threshold.

The output delay circuit 73 includes a capacitor C2, a fourth operational amplifier U1D, a resistor R13, a resistor R14, a resistor R15 and a resistor R16. The output end of the peak value comparison circuit is connected to the capacitor C2 through the resistor R15, the output end of the average value comparison circuit is also connected to the same end of the capacitor C2 through the resistor R16, and the other end of the capacitor C2 is grounded and connected to the positive input end of the fourth operational amplifier U1D , the resistor R13 and the resistor R14 are connected in series to divide the working voltage such as 5V and the ground, and the node between the resistor R13 and the resistor R14 is connected to the inverting input terminal of the fourth operational amplifier U1D as a reference voltage. Therefore, the high-level signals output by the peak value comparison circuit 721 and the average value comparison circuit 722 indicating poor insulation will charge the capacitor C2, and when the voltage value on the capacitor C2 is connected to the positive input terminal of the fourth operational amplifier U1D When the voltage value increases to be higher than the reference voltage of the inverting input terminal, the signal output terminal of the fourth operational amplifier U1D will generate a high-level leakage protection signal output. Output to the step-up microcontroller 50 and the inverter microcontroller 60, so as to prevent leakage protection from malfunctioning.

The utility model also provides a vehicle-mounted inverter correspondingly, which includes a DC filter circuit 10, a DC/DC boost circuit 20, a DC/AC inverter circuit 30, and an AC filter circuit 40 as shown in FIG. The boost microcontroller 50 for controlling the DC/DC boost circuit 20 and the inverter microcontroller 60 for controlling the DC/AC inverter circuit 30 . The vehicle-mounted inverter provided by the utility model also includes the above-mentioned leakage protection circuit of the vehicle-mounted inverter, such as the leakage protection circuit 70 shown in FIG. 2 .

To sum up, the utility model provides an insulation monitoring and leakage protection circuit for a vehicle-mounted inverter. The insulation resistance of the AC output terminal of the vehicle-mounted inverter is detected by using an insulation resistance detection circuit, and the insulation resistance is lower than the preset value. When the threshold is reached, a poor insulation signal is generated. After the signal lasts for more than a preset time, the leakage protection signal is output to control the inverter microcontroller of the vehicle-mounted inverter to stop the DC/AC inversion, and it is cut off quickly when the output AC voltage is poorly insulated from the ground. Inverter AC output. The technical scheme of the utility model makes the vehicle-mounted inverter product fully comply with the relevant safety regulations. When the product used by the user has poor insulation to the ground, the inverter stops working to prevent electric shock accidents, and once an electric shock accident occurs, the inverter stops quickly. output so as to effectively protect the safety of users.

The utility model is described according to specific embodiments, but those skilled in the art should understand that various changes and equivalent replacements can be made without departing from the scope of the utility model. In addition, in order to adapt to the specific occasion or material of the technology of the utility model, many modifications can be made to the utility model without departing from its protection scope. Therefore, the invention is not limited to the specific embodiments disclosed herein, but includes all embodiments falling within the scope of the claims.

Claims (9)

1. the leakage protection circuit of a vehicle-mounted inverter; Said vehicle-mounted inverter comprises DC filtering circuit, DC/DC booster circuit, DC/AC inverter circuit and ac filter circuit, and boost microcontroller and the inversion microcontroller that is used to control the DC/AC inverter circuit that are used to control the DC/DC booster circuit; It is characterized in that said leakage protection circuit comprises: insulation resistance testing circuit, comparison circuit and output delay circuit;

Said insulation resistance testing circuit input is connected with the ac output end of said vehicle-mounted inverter, and output links to each other with said comparison circuit input, and the insulation resistance detection signal that produces is sent to said comparison circuit;

Said comparison circuit output is connected with said output delay circuit input, and said comparison circuit receives said insulation resistance detection signal, and the defective insulation signal that will when insulation resistance is lower than predetermined threshold value, produce sends to said output delay circuit;

The output of said output delay circuit is connected with the said microcontroller that boosts; Said output delay circuit receives said defective insulation signal; And will the duration send to said inversion microcontroller above the earth leakage protective signal that produces behind the Preset Time, stop to exchange output and boost.

2. the leakage protection circuit of vehicle-mounted inverter according to claim 1 is characterized in that, said output delay circuit also links to each other with the said microcontroller that boosts, and said earth leakage protective signal is sent to the said microcontroller that boosts stop the DC/DC boosting inverter.

3. the leakage protection circuit of vehicle-mounted inverter according to claim 2 is characterized in that, the said microcontroller that boosts also is connected with failure alarm circuit, receives said earth leakage protective signal and exports failure alarm signal.

4. the leakage protection circuit of vehicle-mounted inverter according to claim 1 is characterized in that, said leakage protection circuit also comprises the input filter circuit that is connected between said insulation resistance testing circuit and the comparison circuit.

5. the leakage protection circuit of vehicle-mounted inverter according to claim 4 is characterized in that, said comparison circuit further comprises:

The peak value comparison circuit and the mean value comparison circuit of parallel connection; The input of said peak value comparison circuit and mean value comparison circuit links to each other with said input filter circuit output; Output inserts the output delay circuit, and the defective insulation signal that defective insulation signal that respectively peakedness ratio is produced and mean value relatively produce sends to said output delay circuit.

6. the leakage protection circuit of vehicle-mounted inverter according to claim 5; It is characterized in that; Said input filter circuit comprises the first amplifier U1A, capacitor C 4 and resistance R 24; The positive input of the said first amplifier U1A links to each other with the output of said insulation resistance testing circuit, and through capacitor C 4 ground connection; The signal output part of the said first amplifier U1A and positive input short circuit are formed voltage follower; The signal output part of the said first amplifier U1A is also through resistance R 24 ground connection and as the output of input filter circuit.

7. the leakage protection circuit of vehicle-mounted inverter according to claim 6 is characterized in that:

Said peak value comparison circuit comprises: the second amplifier U1B, resistance R 17, resistance R 10, resistance R 19, resistance R 20; The positive input of the said second amplifier U1B is connected to the output of said input filter circuit through resistance R 20; Said resistance R 10 and R19 are connected on and carry out dividing potential drop between operating voltage and the ground, and the node between said resistance R 10 and the R19 inserts the reverse input end of the second amplifier U1B; The signal output part of the said second amplifier U1B is through resistance R 17 ground connection, and access output delay circuit;

Said mean value comparison circuit comprises: the 3rd amplifier U1C, resistance R 18, resistance R 21, resistance R 22, resistance R 23 and capacitor C 3; The positive input of said the 3rd amplifier U1C is connected to the output of said input filter circuit through resistance R 23, and passes through capacitor C 3 ground connection; Said resistance R 21 and R22 are connected on and carry out dividing potential drop between operating voltage and the ground, and the node between said resistance R 21 and the R22 inserts the reverse input end of the 3rd amplifier U1C; The signal output part of said the 3rd amplifier U1C is through resistance R 18 ground connection, and access output delay circuit.

8. the leakage protection circuit of vehicle-mounted inverter according to claim 7 is characterized in that, said output delay circuit comprises capacitor C 2, four high guaily unit U1D, resistance R 12, resistance R 13, resistance R 14, resistance R 15 and resistance R 16;

Wherein, Said peakedness ratio connects capacitor C 2 than circuit output end through resistance R 15; Mean value comparison circuit output also connects the same end of capacitor C 2 through resistance R 16, capacitor C 2 other end ground connection, and insert the positive input of said four high guaily unit U1D; Said resistance R 13 and resistance R 14 are connected on carries out dividing potential drop between operating voltage and the ground, and the node between said resistance R 13 and the resistance R 14 inserts the reverse input end of four high guaily unit U1D; The signal output part of said four high guaily unit U1D is through resistance R 12 ground connection, and as the output of said output delay circuit.

9. a vehicle-mounted inverter comprises DC filtering circuit, DC/DC booster circuit, DC/AC inverter circuit and ac filter circuit, and boost microcontroller and the inversion microcontroller that is used to control the DC/AC inverter circuit that are used to control the DC/DC booster circuit; It is characterized in that said vehicle-mounted inverter also comprises the leakage protection circuit of any described vehicle-mounted inverter among the claim 1-8.

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