WO2021185203A1

WO2021185203A1 - Pre-charge circuit and vehicle

Info

Publication number: WO2021185203A1
Application number: PCT/CN2021/080766
Authority: WO
Inventors: 徐哲敏; 尹连杰; 刘闫涛; 王成志
Original assignee: 比亚迪股份有限公司
Priority date: 2020-03-20
Filing date: 2021-03-15
Publication date: 2021-09-23
Also published as: CN212380957U

Abstract

Disclosed are a pre-charge circuit and a vehicle. The pre-charge circuit comprises a reference circuit (10), an adjustment circuit (20), a detection circuit (30), and a pre-charge transistor (Q1), wherein the reference circuit is used to provide a reference voltage to the adjustment circuit; the detection circuit is used to detect the voltage and current of the pre-charge transistor, and the detection circuit can send the detected voltage and the detected current to the adjustment circuit; and the adjustment circuit is adapted to receive the reference voltage, the detected voltage and the detected current, and the adjustment circuit can adjust the equivalent resistance of the pre-charge transistor using the reference voltage, the detected voltage and the detected current. A pre-charge transistor is used as a buffer component to prevent the generation of a large charging current when power is supplied to a direct-current high-voltage bus. There is no impact peak with regard to the pre-charge transistor, and therefore, the problem of fixed resistor type selection is solved.

Description

Pre-charging circuit and car

Cross-references to related applications

This disclosure is based on a Chinese patent application with an application number of 202020372462.7 and an application date of March 20, 2020, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby incorporated by reference into this disclosure.

Technical field

The present disclosure relates to the field of electrical technology, and in particular to a pre-charging circuit and an automobile.

Background technique

Electric vehicles use the electrical energy supplied by the power supply as the energy source, and the power supply provides electrical energy for various electrical equipment on the electric vehicle, such as motor controllers and DC/AC converters. In general, electrical equipment is connected in parallel on a DC high-voltage bus, and the DC high-voltage bus is provided with a pre-charging capacity. When the voltage of the initial state of the pre-charging capacitor is very small or zero, its instantaneous impedance also approaches zero; in this case, the moment when the DC high-voltage bus is powered, a large charging current will be generated, which will cause The pre-charge capacitor is damaged due to current impact, and the main switch is damaged.

Generally, in order to solve the above-mentioned problems, a fixed resistance is usually added to reduce the voltage across the switch, so as to avoid generating a large charging current at the moment when the DC high-voltage bus is supplied with power. However, the impulse peak power of the above-mentioned fixed resistance is very large, but the average power is relatively small, which brings difficulties to the selection of the fixed resistance.

Summary of the invention

The purpose of the present disclosure is to provide a pre-charging circuit and a car to solve the above-mentioned problems, using a pre-charging transistor instead of a fixed resistor, so that when the power supplies the DC high-voltage bus, there is no current impact while avoiding the selection of fixed resistors. The problem.

The first aspect of the present disclosure provides a precharge circuit, including a reference circuit, an adjustment circuit, a detection circuit, and a precharge transistor; the adjustment circuit is respectively connected to the reference circuit, the detection circuit, and the precharge transistor; The detection circuit is connected to the precharge transistor; the reference circuit is used to provide a reference voltage to the adjustment circuit; the detection circuit is used to detect the voltage and current of the precharge transistor, and the detection circuit can The detection voltage and the detection current are sent to the adjustment circuit; the adjustment circuit is adapted to receive the reference voltage, the detection voltage, and the detection current, and the adjustment circuit can use the reference voltage, the The detection voltage and the detection current adjust the equivalent resistance of the precharge transistor.

The precharge circuit as described above, wherein the detection circuit includes a current sampling element, a current detection unit, and a voltage detection unit; the current sampling element and the precharge transistor are connected in series, and the input terminal of the current detection unit and the voltage detection unit are connected in series. The current sampling element is connected, the output terminal of the current detection unit is connected with the adjustment circuit; the input terminal of the voltage detection unit is connected with the precharge transistor, and the output terminal of the voltage detection unit is connected with the adjustment circuit connect.

The precharge circuit as described above, wherein the adjustment circuit includes a multiplier, a first comparator, and a protection resistor; the positive input terminal of the first comparator is connected to the reference circuit, and the first comparator The negative input terminal is connected to the output terminal of the multiplier, the output terminal of the first comparator is connected to the precharge transistor; the first input terminal of the multiplier is connected to the output terminal of the current detection unit, The second input terminal of the multiplier is connected to the output terminal of the voltage detection unit; the two ends of the protection resistor are respectively connected to the positive input terminal of the first comparator and the ground.

The pre-charging circuit as described above, wherein the current sampling element includes a sampling resistor; the current detecting unit includes a second resistor, a third resistor, and a second comparator; the first end of the second resistor and the The first end of the sampling resistor is connected, and the second end of the second resistor is respectively connected to the first end of the third resistor and the negative input end of the second comparator; the positive input of the second comparator The terminal is connected to the second terminal of the sampling resistor, and the output terminal of the second comparator and the second terminal of the third resistor are both connected to the first input terminal of the multiplier.

The pre-charging circuit as described above, wherein the current sampling element includes a current sensor; the current sensor includes a first terminal, a second terminal, a third terminal, and a fourth terminal; the current sensor passes through the first terminal And the second terminal are connected in series with the precharge circuit; the current detection unit includes a first resistor, a second resistor, a third resistor, and a second comparator; the first terminal of the first resistor and the The third end of the current sensor is connected, the second end of the first resistor is connected to the first end of the second resistor and the fourth end of the current sensor; the second end of the second resistor is connected to the The first terminal of the third resistor is connected to the negative input terminal of the second comparator; the positive input terminal of the second comparator is connected to the second terminal of the current sensor, and the output of the second comparator The terminal and the second terminal of the third resistor are both connected to the first input terminal of the multiplier.

The precharge circuit as described above, wherein the voltage detection unit includes a fourth resistor and a fifth resistor, and the first end of the fourth resistor and the first end of the fifth resistor are respectively connected to the precharge transistor The two ends of are connected; the second end of the fourth resistor and the second end of the fifth resistor are both connected to the second input end of the multiplier.

The precharge circuit as described above, which further includes a drive circuit, the drive circuit includes a drive transistor, a sixth resistor, a seventh resistor, and an eighth resistor; the first end of the fifth resistor and the precharge transistor The first pole of the sixth resistor is connected, the second pole of the sixth resistor and the second pole of the precharge transistor are both connected to the first end of the seventh resistor; the second end of the seventh resistor and the The third pole of the driving transistor is connected; the first terminal of the eighth resistor and the second pole of the driving transistor are both connected to the output terminal of the first comparator, and the second terminal of the eighth resistor is connected to the output terminal of the first comparator. The first poles of the driving transistors are all grounded.

The precharge circuit as described above, wherein the reference circuit includes a fixed reference circuit; the fixed reference circuit includes a ninth resistor, a tenth resistor, and a reference source, and the reference source and the first end of the ninth resistor Connected, the second end of the ninth resistor is connected to the first end of the tenth resistor; the positive input end of the first comparator is connected to the second end of the ninth resistor and the tenth resistor Between the first end of the tenth resistor; the second end of the tenth resistor and the reference source are grounded; or, the reference circuit includes a variable reference circuit, and the variable reference circuit includes an eleventh resistor and an automobile micro-controller In the digital-to-analog converter DAC, the first end of the eleventh resistor and the DAC are both connected to the positive input end of the first comparator; the second end of the eleventh resistor is grounded.

The precharge circuit as described above, wherein the fixed reference circuit further includes a precharge switch connected between the positive input terminal of the first comparator and a connection node, and the connection node is located at the The second end of the ninth resistor and the first end of the tenth resistor.

A second aspect of the present disclosure provides an automobile, including the pre-charging circuit according to any one of the first aspects of the present disclosure.

The precharge circuit provided by the present disclosure includes a reference circuit, an adjustment circuit, a detection circuit, and a precharge transistor; the adjustment circuit is respectively connected to the reference circuit, the detection circuit, and the precharge transistor; the detection circuit and The precharge transistor is connected; the reference circuit provides a reference voltage to the adjustment circuit; after the detection circuit detects the voltage and current of the precharge transistor, it sends the voltage and current to the adjustment circuit; After the adjustment circuit receives the reference voltage, the voltage and the current, it adjusts the equivalent resistance of the precharge transistor by using the reference voltage, the voltage and the current. Use precharge transistors as buffer components to avoid large charging currents at the moment of supplying power to the DC high-voltage bus. In addition, due to the variable equivalent resistance of the precharge transistor, there is no impact peak, which is equivalent to using a component whose resistance can be infinitely changed within a certain range, which solves the problem of fixed resistance selection.

Description of the drawings

In order to explain the technical solutions of the present disclosure more clearly, the following will briefly introduce the drawings that need to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present disclosure, which are common in the art. As far as technical personnel are concerned, without creative work, other drawings can be obtained like these drawings.

FIG. 1 is a structural block diagram of a precharge circuit provided by an embodiment of the present disclosure;

Figure 2 is a structural block diagram of a precharge circuit provided by an embodiment of the present disclosure;

FIG. 3 is a circuit diagram of a precharge circuit provided by Embodiment 1 of the present disclosure;

4 is a circuit diagram of a pre-charging circuit provided in the second embodiment of the present disclosure;

FIG. 5 is a circuit diagram of the precharge circuit provided in the third embodiment of the present disclosure.

Reference signs:

10-reference circuit, 20-adjusting circuit, 30-detection circuit, 31-current sampling unit, 32-current detection unit, 33-voltage detection unit, Q1-precharge transistor, Q2-drive transistor, M-multiplier, C1 -First comparator, C2-second comparator, RL-protection resistor, R1-sampling resistor, R20-first resistor, R2-second resistor, R3-third resistor, R4-fourth resistor, R5-th Five resistors, R6-sixth resistor, R7-seventh resistor, R8-eighth resistor, R9-ninth resistor, R10-tenth resistor, R11-eleventh resistor, S-current sensor, RS-reference source, K-precharge switch, CL-precharge capacity.

Detailed ways

The technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present disclosure.

Please refer to FIG. 1, the precharge circuit provided by the embodiment of the present disclosure includes a reference circuit 10, an adjustment circuit 20, a detection circuit 30, and a precharge transistor Q1; the adjustment circuit 20 is respectively connected to the reference circuit 10, the detection circuit 30 and the precharge transistor Q1 Connected; the detection circuit 30 is connected to the precharge transistor Q1;

The reference circuit 10 is used to provide a reference voltage to the adjustment circuit 20; the detection circuit 30 is used to detect the voltage and current of the precharge transistor Q1, and the detection circuit can send the detection voltage and detection current to the adjustment circuit 20; that is, the detection circuit 30 After detecting the voltage and current of the precharge transistor Q1, the detection voltage and detection current are sent to the adjustment circuit 20; the adjustment circuit 20 is adapted to receive the reference voltage, the detection voltage and the detection current, and the adjustment circuit can use the reference voltage and the detection voltage And the detection current adjusts the equivalent resistance of the precharge transistor Q1; that is, after the adjustment circuit 20 receives the reference voltage, the detection voltage and the detection current, the reference voltage, the detection voltage and the detection current are used to adjust the equivalent resistance of the precharge transistor Q1.

In the present disclosure, the pre-charge transistor Q1 is used as a buffer component to avoid generating a large charging current at the moment of supplying power to the DC high-voltage bus. In addition, due to the variable equivalent resistance of the precharge transistor Q1, there is no impact peak, which is equivalent to using a component whose resistance can be changed infinitely within a certain range, which solves the problem of fixed resistance selection.

Referring to FIG. 2, it can be seen that the detection circuit 30 includes a current sampling element 31, a current detection unit 32, and a voltage detection unit 33. The current sampling component 31 is connected in series with the precharge transistor Q1, the input terminal of the current detection unit 32 is connected with the current sampling component 31, the output terminal of the current detection unit 32 is connected with the adjustment circuit 20; the input terminal of the voltage detection unit 33 is connected with the precharge transistor Q1 Connected, the output terminal of the voltage detection unit 33 is connected to the adjustment circuit 20. The current sampling component 31 is used to sample the current of the precharge transistor Q1, the current detection unit 32 is used to detect the current of the precharge transistor Q1, and then send the current value to the adjustment circuit 20; the voltage detection unit 33 is used to detect the precharge transistor Q1 , And then send the voltage value to the adjustment circuit 20.

The current sampling element 31 may be a sampling resistor R1 or a current sensor S. The aforementioned reference circuit 10 may be a fixed reference circuit 10 or a variable reference circuit 10.

Several specific embodiments are detailed below for reference.

Example one

Please refer to FIG. 3 in combination with FIG. 1 and FIG. 2 for the precharge circuit provided in the first embodiment of the present disclosure. In the first embodiment, the precharge transistor Q1 is a metal-oxide-semiconductor MOS field effect transistor; current sampling The component 31 is a sampling resistor R1; the reference circuit 10 uses a fixed reference circuit 10.

In the first embodiment, the adjustment circuit 20 includes a multiplier M, a first comparator C1 and a protection resistor RL; the positive input terminal of the first comparator C1 is connected to the reference circuit 10, and the negative input terminal of the first comparator C1 and the multiplier The output terminal of M is connected, the output terminal of the first comparator C1 is connected to the gate of the MOS field effect tube; the first input terminal of the multiplier M is connected to the output terminal of the current detection unit 32, and the second input terminal of the multiplier M It is connected to the output terminal of the voltage detection unit 33; the two ends of the protection resistor RL are respectively connected to the positive input terminal of the first comparator C1 and the ground.

The current detection unit 32 includes a second resistor R2, a third resistor R3, and a second comparator C2; the first end of the second resistor R2 is connected to the first end of the sampling resistor R1, and the second end of the second resistor R2 is respectively connected to the first end of the sampling resistor R1. The first end of the three resistor R3 is connected to the negative input end of the second comparator C2; the positive input end of the second comparator C2 is connected to the second end of the sampling resistor R1, and the output end of the second comparator C2 is connected to the third resistor The second terminal of R3 is connected to the first input terminal of the multiplier M.

The voltage detection unit 33 includes a fourth resistor R4 and a fifth resistor R5. The first end of the fourth resistor R4 and the first end of the fifth resistor R5 are respectively connected to the source of the MOS field effect transistor and the drain of the MOS field effect transistor. ; The second end of the fourth resistor R4 and the second end of the fifth resistor R5 are both connected to the second input end of the multiplier M.

The fixed reference circuit 10 includes a ninth resistor R9, a tenth resistor R10, and a reference source RS. The reference source RS is connected to the first end of the ninth resistor R9, and the second end of the ninth resistor R9 and the first end of the tenth resistor R10 are connected. Connection; the positive input terminal of the first comparator C1 is connected between the second terminal of the ninth resistor R9 and the first terminal of the tenth resistor R10; the second terminal of the tenth resistor R10 and the reference source RS are grounded. In addition, the fixed reference circuit 10 further includes a precharge switch K, which is connected between the positive input terminal of the first comparator C1 and the connection node, and the connection node is located at the second end of the ninth resistor R9 and the tenth resistor R10. The first end.

Please continue to refer to Figure 3. In actual use, after the source of the MOS FET is connected to the sampling resistor R1, it is connected in series between the negative electrode of the power supply and the negative electrode of the capacitor; the drain of the MOS FET and the precharge capacitor CL The negative terminal is connected.

Then, after the precharge switch K is closed, the power supply first charges the MOS field effect tube. After the voltage value of the MOS field effect tube reaches the turn-on voltage of the MOS field effect tube, the MOS field effect tube turns on and starts to charge the precharge capacitor CL Pre-charge.

Since the sampling resistor R1 and the MOS field effect tube are connected in series, the current of the sampling resistor R1 is equal to the current of the MOS field effect tube. The current detection unit 32 detects the current of the sampling resistor R1, that is, detects the current a of the MOS field effect tube, and then the second comparator C2 amplifies the current a and sends it to the first input terminal of the multiplier M. The voltage detection unit 33 detects the voltage b of the MOS field effect transistor using the voltage dividing method, and then sends the voltage b to the second input terminal of the multiplier M. The output voltage c output by the output terminal of the multiplier M is the product of the current a and the voltage b, and then the output voltage c is sent to the negative input terminal of the first comparator C1.

On the other hand, the fixed reference circuit 10 provides a reference voltage U for the positive input terminal of the first comparator C1. Under the action of the feedback voltage of the first comparator C1, the voltage at the positive input terminal and the negative input terminal of the first comparator C1 The values are equal, that is:

U=a*b Formula (1);

Among them, U is the reference voltage, a is the current of the MOS field effect tube, and b is the voltage of the MOS field effect tube.

Set the equivalent resistance of the MOS field effect tube to R, then according to the principle that the voltage value is equal to the product of resistance and current, we can get:

b=a*R Formula (2);

a is the current of the MOS field effect tube, b is the voltage of the MOS field effect tube, and R is the equivalent resistance of the MOS field effect tube.

According to the above formula (1) and formula (2), we can get:

U=a*a*R Formula (3);

Among them, U is the reference voltage, a is the current of the MOS field effect tube, and R is the equivalent resistance of the MOS field effect tube.

Among them, the reference voltage U given by the fixed reference circuit 10 is a fixed value, the current a gradually increases with the time that the precharge switch K is closed, and the voltage b gradually decreases, so the equivalent resistance R is equivalently gradually reduced. . Therefore, the precharging current for precharging the precharging capacity CL is a process of gradual increase, and there is no inrush current.

It can be seen from the above that, in the first embodiment, the MOS field effect transistor is used as the pre-charging device, which can avoid the generation of a large charging current at the moment when the DC high-voltage bus is supplied with power. At the same time, the equivalent resistance of the MOS field effect tube is in a state of change, and there is no fixed resistance selection problem.

In addition, according to the principle that power is equal to voltage multiplied by current, we can get:

P=a*b Formula (4);

Combining formula (1), it can be seen that the value of the power P of the MOS field effect tube is equal to the value corresponding to the reference voltage U. Since the reference voltage U does not change, the power P does not change. Therefore, it can be ensured that the MOS field effect tube is always in a safe working area, its service life is prolonged, and the circuit safety factor is ensured.

Example two

Please refer to FIG. 4 in combination with FIG. 1 and FIG. 2 for the precharge circuit provided in the second embodiment of the present disclosure. The difference between the second embodiment and the first embodiment is that the precharge transistor Q1 is a PNP type triode; the current sampling component 31 Is the current sensor S. The remaining voltage detection unit 33 and adjustment circuit 20 of the reference circuit 10 are the same as in the first embodiment.

In some embodiments, the adjustment circuit 20 includes a multiplier M, a first comparator C1 and a protection resistor RL; the positive input terminal of the first comparator C1 is connected to the reference circuit 10, and the negative input terminal of the first comparator C1 is connected to the multiplication The output terminal of the multiplier M is connected, the output terminal of the first comparator C1 is connected with the base of the PNP transistor; the first input terminal of the multiplier M is connected with the output terminal of the current detection unit 32, and the second input terminal of the multiplier M It is connected to the output terminal of the voltage detection unit 33; the two ends of the protection resistor RL are respectively connected to the positive input terminal of the first comparator C1 and the ground.

The current sensor S includes a first terminal, a second terminal, a third terminal and a fourth terminal; the current sensor is connected in series in the precharge circuit through the first terminal and the second terminal. 4, it can be seen that the first end of the current sensor S is connected to the positive electrode of the power supply, and the second end of the current sensor S is connected to the emitter of the precharge transistor Q1.

The current detection unit 32 includes a first resistor R20, a second resistor R2, a third resistor R3, and a second comparator C2; the first end of the first resistor R20 is connected to the third end of the current sensor S, and the first resistor R20 is connected to the third end of the current sensor S. The two ends are connected to the first end of the second resistor R2 and the fourth end of the current sensor S; the first end of the second resistor R2 is connected to the first end of the current sensor S, and the second end of the second resistor R2 is respectively connected to the first end of the current sensor S. The first terminal of the three resistor R3 is connected to the negative input terminal of the second comparator C2; the positive input terminal of the second comparator C2 is connected to the second terminal of the current sensor S, and the output terminal of the second comparator C2 is connected to the third resistor The second terminal of R3 is connected to the first input terminal of the multiplier M.

The voltage detection unit 33 includes a fourth resistor R4 and a fifth resistor R5. The first end of the fourth resistor R4 and the first end of the fifth resistor R5 are respectively connected to the emitter of the PNP transistor and the collector of the PNP transistor; The second end of the four resistor R4 and the second end of the fifth resistor R5 are both connected to the second input end of the multiplier M.

Please continue to refer to Figure 4, in actual use, the emitter of the PNP transistor is connected to the current sensor S, and then connected to the positive pole of the power supply; the collector of the PNP transistor is connected to the positive pole of the precharge capacitor CL.

It can be understood that the PNP-type triode in the second embodiment is connected between the positive electrode of the power supply and the positive electrode of the pre-charging capacitor CL. Therefore, a driving circuit is also required to drive the PNP-type triode. The driving circuit is connected between the PNP transistor and the output terminal of the first comparator C1. In some embodiments, the driving circuit includes a driving transistor Q2, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8; the first end of the sixth resistor R6 is connected to the first electrode of the precharge transistor Q1, and the sixth resistor The second terminal of R6 and the second terminal of the precharge transistor Q1 are both connected to the first terminal of the seventh resistor R7; the second terminal of the seventh resistor R7 is connected to the third terminal of the driving transistor Q2; the second terminal of the eighth resistor R8 is connected to the first terminal of the seventh resistor R7. One end and the second electrode of the driving transistor Q2 are both connected to the output end of the first comparator C1, and the second end of the eighth resistor R8 and the first electrode of the driving transistor Q2 are both grounded.

According to some embodiments of the present disclosure, in the second embodiment, the driving transistor Q2 specifically uses an NPN type transistor, and the precharge transistor Q1 uses a PNP type transistor. Then, the first end of the sixth resistor R6 is connected to the emitter of the PNP transistor, the second end of the sixth resistor R6 and the base of the PNP transistor are both connected to the first end of the seventh resistor R7; the seventh resistor R7 The second end of the eighth resistor R8 is connected to the collector of the NPN transistor; the first end of the eighth resistor R8 and the base of the NPN transistor are both connected to the output end of the first comparator C1, and the second end of the eighth resistor R8 is connected to the NPN The emitter of the PNP transistor is connected to the ground; the emitter of the PNP transistor is connected to the positive pole of the power supply, and the collector of the PNP transistor is connected to the positive pole of the precharge capacitor CL.

Then, after the pre-charge switch K is closed, the power supply first charges the PNP-type transistor. After the voltage value of the PNP-type transistor reaches the turn-on voltage of the PNP-type transistor, the PNP-type transistor is turned on and starts to pre-charge the pre-charge capacitor CL.

Since the current sensor S and the PNP type transistor are connected in series, the current of the current sensor S is equal to the current of the PNP type transistor. The current detection unit 32 detects the current of the current sensor S, that is, detects the current a of the PNP transistor, and then the second comparator C2 amplifies the current a and sends it to the first input terminal of the multiplier M. The voltage detection unit 33 detects the voltage b of the PNP transistor by the voltage division method, and sends the voltage b to the second input terminal of the multiplier M. The output voltage c output by the output terminal of the multiplier M is the product of the current a and the voltage b, and then the output voltage c is sent to the negative input terminal of the first comparator C1.

U=a*b Formula (1);

Among them, U is the reference voltage, a is the current of the PNP transistor, and b is the voltage of the PNP transistor.

Set the equivalent resistance of the PNP transistor to R, then according to the principle that the voltage value is equal to the product of resistance and current, we can get:

b=a*R Formula (2);

a is the current of the PNP transistor, b is the voltage of the PNP transistor, and R is the equivalent resistance of the PNP transistor.

According to the above formula (1) and formula (2), we can get:

U=a*a*R Formula (3);

Among them, U is the reference voltage, a is the current of the PNP transistor, and R is the equivalent resistance of the PNP transistor.

Among them, the reference voltage U given by the fixed reference circuit 10 is a fixed value, and the voltage b gradually decreases with the time that the precharge switch K is closed, and the current a gradually increases, and the equivalent resistance R is equivalently gradually reduced. . Therefore, the precharging current for precharging the precharging capacity CL is a process of gradual increase, and there is no inrush current.

It can be seen from the above that the use of a PNP transistor as a pre-charging device can avoid the moment when the DC high-voltage bus is supplied with a large charging current. At the same time, the equivalent resistance of the PNP transistor is in a changing state, and there is no fixed resistance selection problem.

P=a*b Formula (4);

Combining formula (1), it can be seen that the value of the power P of the PNP-type transistor is equal to the value corresponding to the reference voltage U. Since the reference voltage U does not change, the power P does not change. Therefore, it can be ensured that the PNP type triode is always in a safe working area, its service life is prolonged, and the circuit safety factor is ensured.

Example three

The difference between the third embodiment and the second embodiment is that the current sampling element 31 uses a sampling resistor R1 and the reference circuit 10 uses a variable reference circuit 10. The principle is the same as that of the second embodiment, which will be described in detail below.

Please refer to FIG. 5 in combination with FIG. 1 and FIG. 2. In the third embodiment, the adjustment circuit 20 includes a multiplier M, a first comparator C1 and a protection resistor RL; the positive input terminal of the first comparator C1 is connected to the reference circuit 10 , The negative input terminal of the first comparator C1 is connected to the output terminal of the multiplier M, and the output terminal of the first comparator C1 is connected to the base of the PNP transistor; the first input terminal of the multiplier M is connected to the current detection unit 32 The output terminal is connected, the second input terminal of the multiplier M is connected to the output terminal of the voltage detection unit 33; the two ends of the protection resistor RL are respectively connected to the positive input terminal of the first comparator C1 and ground.

The variable reference circuit 10 includes an eleventh resistor R11 and a digital-to-analog converter DAC. The first terminal of the eleventh resistor R11 and the DAC are both connected to the positive input terminal of the first comparator C1; the second terminal of the eleventh resistor R11 The terminal is grounded. It can be understood that the DAC is a component in a microcontroller unit (MCU) on an automobile. In this solution, the MCU can provide the power of the precharge transistor Q1 according to actual needs, as long as it does not exceed the safe working area of the precharge transistor Q1. Because the power that the precharge transistor Q1 can withstand varies with the voltage applied across the precharge transistor Q1, this scheme can adjust the power consumption P of the precharge transistor Q1 according to the voltage change across the precharge transistor Q1. The change can maximize the potential of the pre-charge transistor Q1, so that the pre-charge circuit can be charged faster and can be applied in a wider range.

It can be understood that, in the third embodiment, the PNP type triode is connected between the positive electrode of the power supply and the positive electrode of the precharge capacitor CL. Therefore, a driving circuit is also required to drive the PNP type triode. The driving circuit is connected between the PNP transistor and the output terminal of the first comparator C1. In some embodiments, the driving circuit includes a driving transistor Q2, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8; the first end of the sixth resistor R6 is connected to the first electrode of the precharge transistor Q1, and the sixth resistor The second terminal of R6 and the second terminal of the precharge transistor Q1 are both connected to the first terminal of the seventh resistor R7; the second terminal of the seventh resistor R7 is connected to the third terminal of the driving transistor Q2; the second terminal of the eighth resistor R8 is connected to the first terminal of the seventh resistor R7. One end and the second electrode of the driving transistor Q2 are both connected to the output end of the first comparator C1, and the second end of the eighth resistor R8 and the first electrode of the driving transistor Q2 are both grounded.

According to some embodiments of the present disclosure, the driving transistor Q2 specifically uses an NPN transistor, and the precharge transistor Q1 uses a PNP transistor. Then, the first end of the sixth resistor R6 is connected to the emitter of the PNP transistor, the second end of the sixth resistor R6 and the base of the PNP transistor are both connected to the first end of the seventh resistor R7; the seventh resistor R7 The second end of the eighth resistor R8 is connected to the collector of the NPN transistor; the first end of the eighth resistor R8 and the base of the NPN transistor are both connected to the output end of the first comparator C1, and the second end of the eighth resistor R8 is connected to the NPN The emitter of the PNP transistor is connected to the ground; the emitter of the PNP transistor is connected to the positive pole of the power supply, and the collector of the PNP transistor is connected to the positive pole of the precharge capacitor CL.

Please continue to refer to Figure 5. In actual use, the emitter of the PNP transistor is connected to the positive electrode of the power supply; the collector of the PNP transistor is connected to the positive electrode of the pre-charging capacitor CL; the sampling resistor R1 is connected to the negative electrode of the power supply and pre-charged Between the negative poles of the capacity CL.

Since the sampling resistor R1 and the PNP transistor are connected in series in the circuit, the current of the sampling resistor R1 is equal to the current of the PNP transistor. The current detection unit 32 detects the current of the sampling resistor R1, that is, detects the current a of the PNP transistor, and then the second comparator C2 amplifies the current a and sends it to the first input terminal of the multiplier M. The voltage detection unit 33 detects the voltage b of the PNP transistor by the voltage division method, and sends the voltage b to the second input terminal of the multiplier M. The output voltage c output by the output terminal of the multiplier M is the product of the current a and the voltage b, and then the output voltage c is sent to the negative input terminal of the first comparator C1.

On the other hand, the variable reference circuit 10 provides a reference voltage U for the positive input terminal of the first comparator C1. Under the action of the feedback voltage of the first comparator C1, the positive input terminal and the negative input terminal of the first comparator C1 The voltage values are equal, that is:

U=a*b Formula (1);

b=a*R Formula (2);

According to the above formula (1) and formula (2), we can get:

U=a*a*R Formula (3);

P=a*b Formula (4);

The embodiment of the present disclosure also provides an automobile, which includes the pre-charging circuit of any embodiment of the present disclosure.

The embodiments of the present disclosure are described in detail above, and specific examples are used in this article to illustrate the principles and implementation of the present disclosure. The descriptions of the above embodiments are only used to help understand the methods and core ideas of the present disclosure; at the same time, for Those of ordinary skill in the art, based on the ideas of the present disclosure, will have changes in the specific implementation and the scope of application. In summary, the content of this specification should not be construed as limiting the present disclosure.

Claims

A precharge circuit, which includes a reference circuit, an adjustment circuit, a detection circuit, and a precharge transistor; the adjustment circuit is respectively connected to the reference circuit, the detection circuit, and the precharge transistor; the detection circuit and The precharge transistor is connected;

The reference circuit is used to provide a reference voltage to the adjustment circuit;

The detection circuit is used to detect the voltage and current of the precharge transistor, and the detection circuit can send the detection voltage and the detection current to the adjustment circuit;

The adjustment circuit is adapted to receive the reference voltage, the detection voltage and the detection current, and the adjustment circuit can use the reference voltage, the detection voltage and the detection current to adjust the precharge transistor Equivalent resistance.
The pre-charging circuit according to claim 1, wherein the detection circuit includes a current sampling element, a current detection unit, and a voltage detection unit;

The current sampling component and the precharge transistor are connected in series, the input terminal of the current detection unit is connected with the current sampling component, and the output terminal of the current detection unit is connected with the adjustment circuit;

The input terminal of the voltage detection unit is connected with the precharge transistor, and the output terminal of the voltage detection unit is connected with the adjustment circuit.
The pre-charging circuit according to claim 2, wherein the adjustment circuit includes a multiplier, a first comparator, and a protection resistor;

The positive input terminal of the first comparator is connected to the reference circuit, the negative input terminal of the first comparator is connected to the output terminal of the multiplier, and the output terminal of the first comparator is connected to the preset circuit. Charge transistor connection;

The first input terminal of the multiplier is connected with the output terminal of the current detection unit, and the second input terminal of the multiplier is connected with the output terminal of the voltage detection unit;

The two ends of the protection resistor are respectively connected to the positive input terminal of the first comparator and the ground.
The pre-charging circuit according to claim 3, wherein the current sampling element comprises a sampling resistor;

The current detection unit includes a second resistor, a third resistor, and a second comparator;

The first end of the second resistor is connected to the first end of the sampling resistor, and the second end of the second resistor is respectively connected to the first end of the third resistor and the negative input of the second comparator End connection

The positive input terminal of the second comparator is connected to the second terminal of the sampling resistor, and the output terminal of the second comparator and the second terminal of the third resistor are both connected to the first input of the multiplier端连接。 End connection.
The pre-charging circuit according to claim 3, wherein the current sampling element comprises a current sensor;

The current sensor includes a first end, a second end, a third end, and a fourth end;

The current sensor is connected in series in the precharge circuit through the first terminal and the second terminal;

The current detection unit includes a first resistor, a second resistor, a third resistor, and a second comparator;

The first end of the first resistor is connected to the third end of the current sensor, and the second end of the first resistor is connected to the first end of the second resistor and the fourth end of the current sensor;

The second end of the second resistor is respectively connected to the first end of the third resistor and the negative input end of the second comparator;

The positive input terminal of the second comparator is connected to the second terminal of the current sensor, and the output terminal of the second comparator and the second terminal of the third resistor are both connected to the first input of the multiplier端连接。 End connection.
The precharge circuit according to any one of claims 3 to 5, wherein the voltage detection unit includes a fourth resistor and a fifth resistor, and a first end of the fourth resistor and a second end of the fifth resistor One end is respectively connected to both ends of the precharge transistor;

The second end of the fourth resistor and the second end of the fifth resistor are both connected to the second input end of the multiplier.
The pre-charging circuit according to any one of claims 3 to 5, further comprising a driving circuit, the driving circuit comprising a driving transistor, a sixth resistor, a seventh resistor, and an eighth resistor;

The first terminal of the fifth resistor is connected to the first pole of the precharge transistor, and the second terminal of the sixth resistor and the second pole of the precharge transistor are both connected to the first terminal of the seventh resistor. End connection

The second end of the seventh resistor is connected to the third electrode of the driving transistor;

The first terminal of the eighth resistor and the second pole of the driving transistor are both connected to the output terminal of the first comparator, and the second terminal of the eighth resistor and the first pole of the driving transistor are both connected Grounded.
The precharge circuit according to any one of claims 3 to 5, wherein the reference circuit includes a fixed reference circuit; the fixed reference circuit includes a ninth resistor, a tenth resistor, and a reference source, the reference source and The first end of the ninth resistor is connected, the second end of the ninth resistor is connected to the first end of the tenth resistor; the positive input end of the first comparator is connected to the ninth resistor Between the second end and the first end of the tenth resistor; the second end of the tenth resistor and the reference source are grounded;

Alternatively, the reference circuit includes a variable reference circuit, the variable reference circuit includes an eleventh resistor and a digital-to-analog converter DAC in an automobile microcontroller, and the first end of the eleventh resistor and the DAC Both are connected to the positive input end of the first comparator; the second end of the eleventh resistor is grounded.
The precharge circuit according to claim 8, wherein the fixed reference circuit further comprises a precharge switch connected between the positive input terminal of the first comparator and a connection node, and the connection The node is located at the second end of the ninth resistor and the first end of the tenth resistor.
An automobile, comprising the pre-charging circuit according to any one of claims 1 to 9.