WO2022056920A1

WO2022056920A1 - Charging signal detection circuit and charging signal detection method

Info

Publication number: WO2022056920A1
Application number: PCT/CN2020/116554
Authority: WO
Inventors: 刘鹏飞; 苏碧锋; 吴芝浩; 吴壬华
Original assignee: 深圳欣锐科技股份有限公司
Priority date: 2020-09-21
Filing date: 2020-09-21
Publication date: 2022-03-24
Also published as: CN113366323A; CN113366323B

Abstract

A charging signal detection circuit and a charging signal detection method. The charging signal detection circuit comprises a power supply (101), a constant-current source circuit (120), a voltage division circuit (130), a change-over switch (102), a microcontrol unit (103), and a vehicle ground wire (104); a positive electrode of the power supply (101) is connected to an input end of the constant-current source circuit (120) and an input end of the voltage division circuit (130), and an output end of the constant-current source circuit (120) is connected to a first change-over port of the change-over switch (102); an output end of the voltage division circuit (130) is connected to a second change-over port of the change-over switch (102), a fixed port of the change-over switch (102) is connected to a first end of the microcontrol unit (103), and a second end of the microcontrol unit (103) is connected to the vehicle ground wire (104); when an electric vehicle is charged, the fixed port of the change-over switch (102) is further used for connecting an input end of a charging device (110), and an output end of the charging device (110) is connected to the vehicle ground wire (104), wherein the charging device (110) comprises a charging protection resistor (111). The charging signal detection circuit facilitates accurately determining a charging signal, to accurately determine the current charging state of the electric vehicle.

Description

Charging signal detection circuit and charging signal detection method

technical field

The present application relates to the technical field of electric vehicle charging, and in particular, to a charging signal detection circuit and a charging signal detection method.

Background technique

In the whole vehicle system, the low-voltage ground is the vehicle body, and the grounds of each low-voltage electrical equipment and low-voltage power supply equipment are connected to the vehicle body. In addition, the vehicle body will have a certain impedance when passing current, so that the ground of each device is no longer the same. A potential, thus forming a ground offset, in addition, in the charging system, because the CC signal (representing the charging control signal) and the CP signal (representing the connection detection signal) between the charger and the charger in the charging device are mutually These signals are interactive, and all these signals need to judge the state of the circuit by sampling the amplitude. Therefore, if there is a ground offset, it will seriously affect the judgment of the circuit state.

Application content

The embodiments of the present application provide a charging signal detection circuit and a charging signal detection method, so as to determine the magnitude of the ground offset of the electric vehicle during the charging process, and then correct the acquired charging signal data according to the ground offset to obtain an accurate charging signal, In order to ensure the stability and safety of the charging system of electric vehicles.

A first aspect of the embodiments of the present application provides a charging signal detection circuit, including a power supply, a constant current source circuit, a voltage divider circuit, a switch, a micro-control unit, and a body ground wire; the positive electrode of the power supply is connected to the constant current source circuit The input end of the voltage divider circuit and the input end of the voltage divider circuit, the output end of the constant current source circuit is connected to the first switch port of the switch; the output end of the voltage divider circuit is connected to the second switch port of the switch switch port, the fixed port of the switch is connected to the first end of the micro-control unit, and the second end of the micro-control unit is connected to the ground wire of the body; when the electric vehicle is charging, the The fixed port is also used to connect the input end of the charging device, and the output end of the charging device is connected to the body ground wire, wherein the charging device includes a charging protection resistor; the micro-control unit is used for charging the electric vehicle during the charging process. Control the switch to connect to a constant current source circuit or a voltage divider circuit, and to detect the voltage value of the fixed port of the switch, and to determine the offset value according to the voltage value, according to the ground offset Shift correction to get accurate charging signal.

In one embodiment, the voltage divider circuit includes a first resistor, a first end of the first resistor is connected to the positive electrode of the power supply, and a second end of the first resistor is connected to the positive electrode of the switch. The second switching port; the first resistor is an adjustable resistor or a fixed resistor with a known resistance value.

In one embodiment, the constant current source circuit includes a first resistor, a second resistor, a third resistor, a first transistor, a second transistor, a first operational amplifier, a second operational amplifier and a voltage adjustment device ; The positive pole of the power supply is respectively connected to the first end of the first resistor and the first end of the second resistor; the second end of the first resistor is respectively connected to the collector of the first transistor and the The non-inverting input terminal of the second operational amplifier; the base of the first transistor is connected to the output terminal of the first operational amplifier; the non-inverting input terminal of the first operational amplifier is connected to the voltage regulating device, so The inverting input end of the first operational amplifier is connected to the first end of the third resistor; the emitter of the first triode is connected to the first end of the third resistor; the second end of the third resistor is connected The second end of the second resistor is connected to the inverting input end of the second operational amplifier and the emitter of the second triode respectively; the output of the second operational amplifier The terminal is connected to the base of the second triode; the collector of the second triode is connected to the first switching port of the switch; the voltage adjustment device is used to output voltages of different amplitudes to Regulates the current flowing through the toggle switch.

In one embodiment, the constant current source circuit includes a triode, a zener diode, a first resistor and a second resistor; the positive pole of the power supply is connected to the first end of the first resistor and the zener diode, respectively. Negative electrode, the positive electrode of the Zener diode is connected to the first port of the second resistor, the second port of the second resistor is connected to the body ground wire; the second end of the first resistor is connected to the triode an emitter, the base of the triode is connected to the anode of the zener diode, and the collector of the triode is connected to the first switch port of the switch.

In one embodiment, the constant current source circuit includes a capacitor, a first resistor, a second resistor, a third resistor, a first transistor and a second transistor, a common diode and a TL431 chip, wherein the power supply The positive pole of the capacitor is respectively connected to the first end of the capacitor, the first end of the first resistor and the first end of the second resistor; The collector of a triode and the base of the second triode; the reference electrode of the TL431 is connected to the first end of the third resistor; the anode of the TL431 is connected to the first end of the switch a switching port; the second end of the first resistor is connected to the emitter of the first triode; the base of the first triode is connected to the collector of the second triode; the third The second end of the second resistor is connected to the anode of the common diode; the cathode of the common diode is connected to the collector of the second triode; the emitter of the second triode is connected to the third resistor of the third resistor one end; the second end of the third resistor is connected to the first switch port of the switch.

In one embodiment, the constant current source circuit includes a zener diode, a first resistor, a second resistor, an operational amplifier and a triode, wherein the positive electrode of the power supply is connected to the negative electrode of the zener diode and the first The first end of a resistor and the second end of the first resistor are respectively connected to the inverting input end of the operational amplifier and the emitter of the triode; the positive electrode of the zener diode is respectively connected to the second end of the resistor the first end and the non-inverting input end of the operational amplifier; the second end of the second resistor is connected to the body ground wire, the output end of the operational amplifier is connected to the base of the triode, and the collector of the triode The first switch port of the switch is connected.

In one embodiment, the constant current source circuit includes a first operational amplifier, a second operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor, wherein the positive electrode of the power supply is connected to the first end of the first resistor, and the second end of the first resistor is respectively connected to the first end of the second resistor and the non-inverting input end of the first operational amplifier; The inverting input terminal is connected to the first terminal of the fifth resistor; the second terminal of the second resistor is respectively connected to the inverting input terminal and the output terminal of the second operational amplifier, and the non-inverting input of the second operational amplifier The terminal is connected to the first switching port of the switch; the output terminal of the first operational amplifier is respectively connected to the first terminal of the third resistor and the first terminal of the fourth resistor, and the first terminal of the third resistor The two ends are connected to the first switch port of the switch; the second end of the fourth resistor is connected to the first end of the fifth resistor, and the second end of the fifth resistor is connected to the vehicle body ground wire.

In one embodiment, when different components are connected to different positions of the ground wire of the vehicle, there is a resistance value between the components.

A second aspect of an embodiment of the present application provides a charging signal detection method, which is applied to the charging signal detection circuit described in the first aspect, including: when the electric vehicle is being charged, the micro-control unit controls the switch to conduct turn on the first switch port or the second switch port; when the first switch port is turned on, the micro-control unit detects the voltage V ₁ of the fixed terminal; when the second switch port is turned on , the micro-control unit detects the voltage V ₂ of the fixed terminal; determines the current I 1 according to the constant current original circuit, determines the current I ₂ according to the voltage V ₂ ; determines the current I ₂ according to the voltage V ₁ and the current I ₁ , the voltage V2 and the current _I2 determine the resistance value of the charging protection resistor _RC and the ground offset value _Vp _; charging signal.

In one embodiment, determining the resistance value of the charging protection resistor RC and the ground offset value V _p according to the voltage V ₁ , the current I ₁ , the voltage V ₂ and the current I ₂ includes: according to the equation set V ₁ =RC*I ₁ +V _p , V ₂ =RC*I ₂ +V _p ; the value of the charging protection resistor RC and the ground offset value V _p are obtained by calculation.

In this application, the charging signal detection circuit includes a power supply, a constant current source circuit, a voltage divider circuit, a switch, a micro-control unit and a vehicle body ground wire; the positive pole of the power supply is connected to the input end of the constant current source circuit and the The input end of the voltage divider circuit, the output end of the constant current source circuit is connected to the first switch port of the switch; the output end of the voltage divider circuit is connected to the second switch port of the switch, the switch The fixed port of the switch is connected to the first end of the micro-control unit, and the second end of the micro-control unit is connected to the ground wire of the body; when the electric vehicle is charging, the fixed port of the switch is also used to connect The input end of the charging device, the output end of the charging device is connected to the body ground wire, wherein the charging device includes a charging protection resistor; the micro-control unit is used to control the switch during the charging process of the electric vehicle to connect the first switch port or the second switch port, and to detect the voltage value of the fixed port of the switch, and to determine the offset value according to the voltage value, according to the ground offset The shift value determines the charging signal. It can be seen that the charging signal detection circuit can switch between the constant current source circuit and the voltage divider circuit to detect the voltage of the connected charging equipment when connecting different circuits, and determine the ground offset of the electric vehicle according to the voltage when connecting different circuits According to the ground offset value of the electric vehicle, the detected voltage value and the corresponding current value are determined to compensate for the actual voltage and current value of the charging device, and then the detected charging signal is determined according to the actual voltage and current value. Correction improves the accuracy of charging signal detection and ensures the stability and safety of the electric vehicle charging process.

These and other aspects of the present application will be more clearly understood in the description of the following embodiments.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the accompanying drawings involved in the embodiments or the background technology of the present application will be briefly introduced below.

The accompanying drawings involved in the embodiments of the present application will be briefly introduced below.

FIG. 1 is a schematic structural diagram of a charging signal detection system provided by an embodiment of the present application;

Fig. 2 is a possible schematic diagram of the constant current source circuit shown in Fig. 1;

3 is a second possible schematic diagram of the constant current source circuit shown in FIG. 1;

FIG. 4 is a third possible schematic diagram of the constant current source circuit shown in FIG. 1;

FIG. 5 is a fourth possible schematic diagram of the constant current source circuit shown in FIG. 1;

6 is a fifth possible schematic diagram of the constant current source circuit shown in FIG. 1;

FIG. 7 is a schematic flowchart of a charging signal detection method provided by an embodiment of the present application.

detailed description

In order to make those skilled in the art better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only The embodiments are part of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the scope of protection of the present application.

Each of them will be described in detail below.

The terms "first", "second", "third" and "fourth" in the description and claims of the present application and the drawings are used to distinguish different objects, rather than to describe a specific order . Furthermore, the terms "comprising" and "having", and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes unlisted steps or units, or optionally also includes For other steps or units inherent to these processes, methods, products or devices.

Reference herein to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor a separate or alternative embodiment that is mutually exclusive of other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

The embodiments of the present application will be introduced below with reference to the accompanying drawings.

Please refer to FIG. 1 . FIG. 1 is a schematic structural diagram of a charging signal detection system provided by an embodiment of the present application, including a charging signal detection circuit 100 and a charging device 110 , wherein the charging signal detection circuit 100 includes a power supply 101 and a constant current source circuit 120 , a voltage divider circuit 130, a switch 102, a micro-control unit 103 and a body ground wire 104;

The positive pole of the power supply 101 is connected to the input end of the constant current source circuit 120 and the input end of the voltage divider circuit 130, and the output end of the constant current source circuit 120 is connected to the first switch port of the switch 102; The output terminal of the voltage divider circuit 130 is connected to the second switch port of the switch 102 , the fixed port of the switch 102 is connected to the first terminal of the micro-control unit 103 , and the second terminal of the micro-control unit 103 is connected. The end is connected to the body ground wire 104;

When the electric vehicle is being charged, the fixed port of the switch 102 is also used to connect the input end of the charging device 110, and the output end of the charging device 110 is connected to the body ground wire, wherein the charging device 110 includes Charging protection resistor 111;

The micro-control unit 103 is used to control the switch 102 to connect the constant current source circuit 120 or the voltage divider circuit 130 during the charging process of the electric vehicle, and to detect the voltage value of the fixed port of the switch 102 , and a ground offset value for determining the ground offset value according to the voltage value, and correcting the ground offset value to obtain an accurate charging signal.

Among them, the parts from endpoint A1 to endpoint A3 in FIG. 1 belong to the body ground wire 104, the end point A1 is the end point where the charging device is connected to the body ground wire, the end point A2 is the end point where the microcontroller unit 103 is connected to the body ground wire 104, and the end point A3 is the power supply 101 is connected to the end point of the body ground wire 104 . It can be seen that the nodes at which different load devices are connected to the body ground wire 104 are different, resulting in resistance between different load devices after being connected to the body ground wire 104. Therefore, the body ground wire can be regarded as equivalently as a very long resistance band , so the potential detected by the micro-control unit 103 between the fixed port of the switch 102 and the terminal A2 is not the potential across the charging device 110, but the potential at both ends of the charging device 110 + the potential between the terminal A1 and the terminal A2, Wherein, the potential between the terminal A1 and the terminal A2 is the ground offset value in the embodiment of the present application.

It can be seen that, in this example, the micro-control unit 103 can control the switch 102 to connect the constant current source circuit 120 or the voltage divider circuit 130, and at the same time detect the fixed port of the switch 102 between the constant current source circuit 120 and the divider The voltage value of the circuit when the voltage circuit 130 is respectively connected, and then the ground offset value caused by the vehicle body ground wire 104 can be determined according to the two detected data, so that the detected voltage can be subsequently determined according to the ground offset value. The corresponding current value is determined and compensated to obtain the actual voltage value and current value of the charging device, and then the detected charging signal is corrected according to the actual voltage value and current value, which improves the accuracy of charging signal detection and ensures that The stability and safety of the electric vehicle charging process.

In a possible example, the voltage divider circuit 130 includes a first resistor, a first end of the first resistor is connected to the positive pole of the power supply, and a second end of the first resistor is connected to the switch The second switching port of the switch 102; the first resistor is an adjustable resistor or a fixed resistor with a known resistance value.

It can be seen that, in this example, the voltage dividing circuit 130 is formed by connecting a fixed resistor or an adjustable resistor into the charging model detection circuit 100, so as to facilitate the calculation according to the voltage value and resistance value of the voltage dividing circuit 130 in the subsequent calculation process The sum of the voltage value across the charging device 110 and the ground offset value is obtained.

In a possible example, please refer to FIG. 2 , which is a possible schematic diagram of the constant current source circuit 120 shown in FIG. 1 , the constant current source circuit 120 includes a first resistor R1 and a second resistor R2 , a third resistor R3, a first transistor B1, a second transistor B2, a first operational amplifier H1, a second operational amplifier H2 and a voltage adjustment device;

The positive pole of the power supply 101 is respectively connected to the first end of the first resistor R1 and the first end of the second resistor R2; the second end of the first resistor R1 is respectively connected to the first transistor B1 The collector of the second operational amplifier H2 and the non-inverting input terminal of the second operational amplifier H2; the base of the first transistor B1 is connected to the output terminal of the first operational amplifier H1; the non-inverting input terminal of the first operational amplifier H1 Connect the voltage adjustment device, the inverting input terminal of the first operational amplifier H1 is connected to the first terminal of the third resistor R3; the emitter of the first transistor B1 is connected to the third resistor R3 the first end; the second end of the third resistor R3 is connected to the body ground wire 104;

The second end of the second resistor R2 is respectively connected to the inverting input end of the second operational amplifier H2 and the emitter of the second transistor B2; the output end of the second operational amplifier H2 is connected to the The base of the second transistor B2; the collector of the second transistor B2 is connected to the first switch port of the switch 102;

The voltage regulating device is used for outputting voltages of different amplitudes to regulate the current flowing through the switch.

It can be seen that in this example, the magnitude of the current flowing through the switch 102 can be adjusted by adjusting the voltage value output by the voltage adjusting device in the constant current source circuit 120, so that the charging signal detection circuit in the embodiment of the present application can be flexibly adapted to Compatible with different power sources and charging devices.

In a possible example, consistent with the above-mentioned FIG. 2 , please refer to FIG. 3 . FIG. 3 is another possible schematic diagram of the constant current source circuit 120 shown in FIG. 1 , where the constant current source circuit 120 includes a triode B1, Zener diode D1, first resistor R1 and second resistor R2;

The anode of the power supply 101 is respectively connected to the first end of the first resistor R1 and the cathode of the Zener diode D1, the anode of the Zener diode D1 is connected to the first port of the second resistor R2, and the Zener diode D1 is connected to the first port of the second resistor R2. The second port of the second resistor R2 is connected to the body ground wire 104;

The second end of the first resistor R1 is connected to the emitter of the transistor B1, the base of the transistor B1 is connected to the anode of the Zener diode D1, and the collector of the transistor B1 is connected to the switch 102. the first switch port.

Among them, the triode B1 is a PNP type triode.

It can be seen that, in this example, a constant current source circuit is formed by a triode, a Zener diode and a resistor, so that the constant current source circuit 120 provides a constant current power supply when the charging signal detection circuit is connected.

In a possible example, consistent with the above-mentioned FIG. 2 and FIG. 3 , please refer to FIG. 4 , FIG. 4 is another possible schematic diagram of the constant current source circuit 120 shown in FIG. 1 , the constant current source circuit 120 includes a capacitor C1, a first resistor R1, a second resistor R2, a third resistor R3, a first transistor B1 and a second transistor B2, a common diode D1 and a TL431 chip, wherein,

The positive pole of the power supply 101 is respectively connected to the first end of the capacitor C1, the first end of the first resistor R1 and the first end of the second resistor R2; the second end of the capacitor C1 is respectively connected to the first end of the capacitor C1. the cathode of the TL431, the collector of the first triode B1 and the base of the second triode B2; the reference electrode of the TL431 is connected to the first end of the third resistor R3; the TL431 The anode is connected to the first switch port of the switch 102;

The second end of the first resistor R1 is connected to the emitter of the first transistor B1; the base of the first transistor B1 is connected to the collector of the second transistor B2;

The second end of the second resistor R2 is connected to the anode of the common diode D1; the cathode of the common diode D1 is connected to the collector of the second transistor B2; the emitter of the second transistor B2 The first end of the third resistor R3 is connected; the second end of the third resistor R3 is connected to the first switch port of the switch 102 .

Among them, the TL431 chip is a shunt voltage regulator integrated circuit, its output voltage can be arbitrarily set to any value in the range of the reference voltage from 2.5V to 36V with two resistors. The typical dynamic impedance of the device is 0.2Ω.

It can be seen that in this example, a constant current source circuit is formed by capacitors, resistors, triodes, common diodes and TL431, so that the constant current source circuit 120 provides a constant current power supply when connected to the charging signal detection circuit.

In a possible example, which is consistent with the above-mentioned FIG. 2 , FIG. 3 and FIG. 4 , please refer to FIG. 5 . FIG. 5 is another possible schematic diagram of the constant current source circuit 120 shown in FIG. 1 . The current source circuit includes a Zener diode D1, a first resistor R1, a second resistor R2, an operational amplifier H1 and a triode B1, wherein,

The anode of the power supply 101 is respectively connected to the cathode of the Zener diode D1 and the first end of the first resistor R1, and the second end of the first resistor R1 is respectively connected to the inverting input end of the operational amplifier H1 and the emitter of the transistor B1; the anode of the Zener diode D1 is respectively connected to the first end of the second resistor R2 and the non-inverting input end of the operational amplifier H1; the second end of the second resistor R2 The vehicle body ground 104 is connected, the output end of the operational amplifier H1 is connected to the base of the transistor B1 , and the collector of the transistor B1 is connected to the first switch port of the switch 102 .

It can be seen that, in this example, a constant current source circuit is formed by a Zener diode, a resistor, an operational amplifier and a triode, so that the constant current source circuit 120 provides a constant current power supply when connected to the charging signal detection circuit.

In a possible example, consistent with the above-mentioned FIG. 2 , FIG. 3 , FIG. 4 and FIG. 5 , please refer to FIG. 6 , FIG. 6 is another possible schematic diagram of the constant current source circuit 120 shown in FIG. 1 , The constant current source circuit includes a first operational amplifier H1, a second operational amplifier H2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a fifth resistor R5, wherein,

The positive pole of the power supply 101 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is respectively connected to the first end of the second resistor R2 and the in-phase of the first operational amplifier H1. input end; the inverting input end of the first operational amplifier H1 is connected to the first end of the fifth resistor R5;

The second terminal of the second resistor R2 is connected to the inverting input terminal and the output terminal of the second operational amplifier H2 respectively, and the non-inverting input terminal of the second operational amplifier H2 is connected to the first switching port of the switch 102 ;

The output end of the first operational amplifier H1 is connected to the first end of the third resistor R3 and the first end of the fourth resistor R4 respectively, and the second end of the third resistor R3 is connected to the switch 102 The second end of the fourth resistor R4 is connected to the first end of the fifth resistor R5 , and the second end of the fifth resistor R5 is connected to the vehicle body ground 104 .

It can be seen that in this example, the constant current source circuit 120 is formed by a resistor and an operational amplifier, so that the constant current source circuit 120 provides a constant current power supply when the charging signal detection circuit is connected.

In a possible example, when different components are connected to different positions of the ground wire 104 of the vehicle, there is a resistance value between the components.

Among them, the body ground wire can be equivalent to a resistance band.

Please refer to FIG. 7. FIG. 7 is a schematic flowchart of a charging signal detection method provided by an embodiment of the present application, which is applied to a charging signal detection circuit. The charging signal detection circuit includes a power supply, a constant current source circuit, a voltage divider circuit, a switching switch, micro-control unit and body ground; the positive pole of the power supply is connected to the input end of the constant current source circuit and the input end of the voltage divider circuit, and the output end of the constant current source circuit is connected to the a first switch port; the output end of the voltage divider circuit is connected to the second switch port of the switch switch, the fixed port of the switch switch is connected to the first end of the micro-control unit, the second end of the micro-control unit is connected The terminal is connected to the body ground wire; when the electric vehicle is being charged, the fixed port of the switch is also used to connect the input terminal of the charging device, and the output terminal of the charging device is connected to the body ground wire, wherein the The charging device includes a charging protection resistor RC; the body ground wire can be equivalent to a resistor, and when different components are connected to different positions of the vehicle ground wire, there is a resistance value between the components;

Step 701, when the electric vehicle is being charged, the micro-control unit controls the switch to turn on the first switch port or the second switch port; when the first switch port is turned on, the micro-control unit detects the voltage V ₁ of the fixed end of the switch; When the second switch port is turned on, the micro-control unit detects the voltage V ₂ of the fixed end of the switch;

Step 702: Determine the current I 1 according to the constant current source circuit, and determine the current I ₂ according to the voltage V ₂ _;

Among them, since the constant current source current is known, the constant output current I ₁ of the constant current source circuit is known, that is, the current flowing through the fixed end of the switch when the switch turns on the first switch port; the voltage divider The resistance of the circuit is known, and the voltage at both ends of the voltage divider circuit can be determined according to the power supply voltage and the detected voltage V ₂ at the fixed terminal. The voltage at both ends of the voltage divider circuit = power supply voltage - voltage V ₂ ; The voltage of the terminal and the resistance of the voltage divider circuit can be calculated to obtain the current I ₂ flowing through the voltage divider circuit, which is the current flowing through the fixed terminal of the switch when the switch turns on the second switch port.

Step 703: Determine the resistance value of the charging protection resistor RC and the ground offset _Vp value according to the voltage V ₁ , the current I ₁ , the voltage V ₂ and the current I ₂ ;

Step 704 , correcting the acquired charging signal according to the ground offset V _p value to obtain an accurate charging signal.

It can be seen that the micro-control unit can control the switch to detect the voltages when the fixed ends of the switch are in the constant current source circuit and the voltage divider circuit respectively, and determine the corresponding current according to the constant current source circuit and the voltage divider circuit, and then pass The two sets of voltage and current calculate the ground offset value, and then determine the accurate charging signal according to the ground offset value, so as to accurately monitor the charging state of the electric vehicle;

In a possible example, the resistance value of the charging protection resistor RC and the ground offset V _p value are determined according to the voltage V ₁ , the current I ₁ , the voltage V ₂ and the current I ₂ ,include:

According to the formula V ₁ =RC*I ₁ +Vp, V ₂ =RC*I ₂ +V _p ; the value of the charging protection resistor RC and the value of the ground offset V _p are obtained by calculation.

It should be noted that, for the sake of simple description, the foregoing application embodiments are all expressed as a series of action combinations, but those skilled in the art should know that the present application is not limited by the described action sequence. Because in accordance with the present application, certain steps may be performed in other orders or concurrently. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

In the above-mentioned embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

In the several embodiments provided in this application, it should be understood that the disclosed apparatus may be implemented in other manners. For example, the device embodiments described above are only illustrative. For example, the division of the above-mentioned units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated. to another system, or some features can be ignored, or not implemented. On the other hand, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical or other forms.

The above-mentioned units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit. The above-mentioned integrated units may be implemented in the form of hardware, or may be implemented in the form of software functional units.

The embodiments of the present application are described in detail above, and specific examples are used to illustrate the principles and implementations of the present application. The descriptions of the above embodiments are only used to help understand the present application and its core ideas; According to the idea of the application, there will be changes in the specific implementation mode and application scope. To sum up, the content of this specification should not be construed as a limitation to the application.

Claims

A charging signal detection circuit, characterized in that it includes a power supply, a constant current source circuit, a voltage divider circuit, a switch, a micro-control unit and a body ground wire;

The positive pole of the power supply is connected to the input end of the constant current source circuit and the input end of the voltage divider circuit, and the output end of the constant current source circuit is connected to the first switch port of the switch; the voltage divider circuit The output end of the switch is connected to the second switch port of the switch, the fixed port of the switch is connected to the first end of the micro-control unit, and the second end of the micro-control unit is connected to the body ground wire;

When the electric vehicle is being charged, the fixed port of the switch is also used to connect the input end of the charging device, and the output end of the charging device is connected to the body ground wire, wherein the charging device includes a charging protection resistor;

The micro-control unit is used to control the switch to connect to a constant current source circuit or a voltage divider circuit during the charging process of the electric vehicle, and to detect the voltage value of the fixed port of the switch, and to detect the voltage value of the fixed port of the switch according to the The voltage value determines a ground offset value, and corrects according to the ground offset value to obtain an accurate charging signal.
The charging signal detection circuit according to claim 1, wherein the voltage divider circuit comprises a first resistor, a first end of the first resistor is connected to the positive electrode of the power supply, and the first resistor The second end of the switch is connected to the second switch port of the switch; the first resistor is an adjustable resistor or a fixed resistor with a known resistance value.
The charging signal detection circuit according to claim 1, wherein the constant current source circuit comprises a first resistor, a second resistor, a third resistor, a first transistor, a second transistor, a first operation an amplifier, a second operational amplifier and a voltage regulator;

The positive pole of the power supply is respectively connected to the first end of the first resistor and the first end of the second resistor; the second end of the first resistor is respectively connected to the collector of the first transistor and the first end of the second resistor. the non-inverting input terminal of the second operational amplifier; the base of the first transistor is connected to the output terminal of the first operational amplifier; the non-inverting input terminal of the first operational amplifier is connected to the voltage regulating device, the The inverting input end of the first operational amplifier is connected to the first end of the third resistor; the emitter of the first triode is connected to the first end of the third resistor; the second end of the third resistor Connect the body ground wire;

The second end of the second resistor is respectively connected to the inverting input end of the second operational amplifier and the emitter of the second triode; the output end of the second operational amplifier is connected to the second triode The base of the transistor; the collector of the second transistor is connected to the first switch port of the switch;

The voltage regulating device is used for outputting voltages of different amplitudes to regulate the current flowing through the switch.
The charging signal detection circuit according to claim 1, wherein the constant current source circuit comprises a triode, a Zener diode, a first resistor and a second resistor;

The positive pole of the power supply is respectively connected to the first end of the first resistor and the negative pole of the Zener diode, the positive pole of the Zener diode is connected to the first port of the second resistor, and the third pole of the second resistor is connected. The second port is connected to the body ground wire;

The second end of the first resistor is connected to the emitter of the transistor, the base of the transistor is connected to the anode of the Zener diode, and the collector of the transistor is connected to the first switch port of the switch .
The charging signal detection circuit according to claim 1, wherein the constant current source circuit comprises a capacitor, a first resistor, a second resistor, a third resistor, a first transistor and a second transistor, a common diode and TL431 chip, which,

The positive electrode of the power supply is respectively connected to the first end of the capacitor, the first end of the first resistor and the first end of the second resistor; the second end of the capacitor is respectively connected to the cathode of the TL431, The collector of the first triode and the base of the second triode; the reference electrode of the TL431 is connected to the first end of the third resistor; the anode of the TL431 is connected to the the first switching port;

The second end of the first resistor is connected to the emitter of the first triode; the base of the first triode is connected to the collector of the second triode;

The second end of the second resistor is connected to the anode of the common diode; the cathode of the common diode is connected to the collector of the second triode; the emitter of the second triode is connected to the third The first end of the resistor; the second end of the third resistor is connected to the first switch port of the switch.
The charging signal detection circuit according to claim 1, wherein the constant current source circuit comprises a Zener diode, a first resistor, a second resistor, an operational amplifier and a triode, wherein,

The anode of the power supply is respectively connected to the cathode of the Zener diode and the first end of the first resistor, and the second end of the first resistor is respectively connected to the inverting input of the operational amplifier and the triode. emitter; the anode of the Zener diode is respectively connected to the first end of the second resistor and the non-inverting input end of the operational amplifier; the second end of the second resistor is connected to the body ground wire, and the operation The output end of the amplifier is connected to the base of the triode, and the collector of the triode is connected to the first switch port of the switch.
The charging signal detection circuit according to claim 1, wherein the constant current source circuit comprises a first operational amplifier, a second operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor and a first Five resistors, where,

The positive pole of the power supply is connected to the first end of the first resistor, and the second end of the first resistor is respectively connected to the first end of the second resistor and the non-inverting input end of the first operational amplifier; the the inverting input end of the first operational amplifier is connected to the first end of the fifth resistor;

The second end of the second resistor is respectively connected to the inverting input end and the output end of the second operational amplifier, and the non-inverting input end of the second operational amplifier is connected to the first switching port of the switch;

The output end of the first operational amplifier is respectively connected to the first end of the third resistor and the first end of the fourth resistor, and the second end of the third resistor is connected to the first switch port of the switch ; The second end of the fourth resistor is connected to the first end of the fifth resistor, and the second end of the fifth resistor is connected to the vehicle body ground wire.
The charging signal detection circuit according to any one of claims 1-7, wherein when different components are connected to different positions of the ground wire of the vehicle, there is a resistance value between the components.
A charging signal detection method, characterized in that, applied to the charging signal detection circuit according to any one of claims 1-8, comprising:

The micro-control unit controls the switch to turn on the first switch port or the second switch port when the electric vehicle is charging; when the first switch port is turned on, the micro-controller The unit detects the voltage V 1 of the fixed terminal of the switch; when the second switch port is turned on, the micro-control unit detects the voltage V 2 of the fixed terminal of the switch;

Determine the current I 1 according to the constant current source circuit, and determine the current I 2 according to the voltage V 2 ;

Determine the resistance value of the charging protection resistor RC and the ground offset value Vp according to the voltage V 1 , the current I 1 , the voltage V 2 and the current I 2 ;

Correction is performed on the acquired charging signal according to the ground offset value V p to obtain an accurate charging signal.
The method according to claim 9 , wherein the resistance value and ground of the charging protection resistor RC are determined according to the voltage V1, the current I1 , the voltage V2 and the current I2 Offset value V p , including:

According to the formula V 1 =RC*I 1 +V p , V 2 =RC*I 2 +V p ; the value of the charging protection resistor RC and the ground offset value V p are obtained by calculation.