CN110549879A - CP signal voltage detection method and device of electric vehicle alternating current charging system - Google Patents

Abstract

The invention discloses a CP signal voltage detection method and device of an electric automobile alternating current charging system, and belongs to the technical field of electric automobile charging. The CP signal voltage detection method of the electric vehicle alternating current charging system comprises the following steps: s1, voltage comparison: the CP signal voltage value is compared with the set voltage value respectively, and high level or low level is output by comparing the voltage values of the CP signal voltage value and the set voltage value; s2, isolating output: the high level or the low level output by the step S1 is converted into a CMOS level signal by an opto-coupler and is input to pins of the MCU respectively; s3, sampling calculation: and reading the level state of the pin through the MCU, and inquiring to obtain the current voltage value. The CP signal voltage detection method of the alternating current charging system of the electric automobile is simple and easy to implement, wide in application scene, capable of improving the reliability of the control and guide function of the alternating current charging pile, capable of reducing the cost and good in popularization and application value.

Description

A CP signal voltage detection method and device for an electric vehicle AC charging system

technical field

The invention relates to the technical field of electric vehicle charging, and specifically provides a method and device for detecting a CP signal voltage of an electric vehicle AC charging system.

Background technique

Electric vehicle charging technology is divided into DC charging and AC charging. Compared with DC charging piles, AC charging piles have certain advantages in terms of volume, cost and installation conditions.

CP stands for charging control guidance, which is used to monitor the interactive function between charging piles and electric vehicles. According to the location where the CP signal is generated and detected, it is divided into four modes. At present, charging piles are widely used in mode three, that is, charging piles provide generation and detection of CP signals, and identify and control charging status.

According to the connection status of the charging cable and the charging pile or electric vehicle, it is divided into three connection methods: A/B/C. Currently, the widely used connection method is C, that is, the charging cable is fixedly connected to the charging pile, and the charging plug is connected to the electric vehicle. In this connection mode, the charging pile needs to judge the status of the plug-in and pull-out of the charging plug through the CP signal.

The CP signal is divided into two states: DC output and PWM output, and the PWM cycle is 1khz. According to the voltage level, there are 3 states 12V, 9V, 6V. Among them, DC/PWM 12V, DC/PWM 9V, and DC/PWM 6V represent three states: the charging plug is not inserted into the electric vehicle socket, the charging plug is inserted into the electric vehicle socket, and the electric vehicle is ready and requests AC output. The charging pile needs to identify the above CP signal voltage state to determine the state of the charging behavior.

Currently, the detection of the CP signal voltage usually adopts an analog-to-digital conversion method. Divided into two ways: external AD chip and using MCU built-in AD. The external AD chip has disadvantages such as complex isolation circuit and high cost, and the MCU built-in AD has disadvantages such as poor precision and weak anti-interference ability.

Contents of the invention

The technical task of the present invention is to address the above existing problems, to provide a CP signal voltage detection method for an electric vehicle AC charging system that is simple and easy to implement, has a wide range of application scenarios, can improve the reliability of the control and guidance function of the AC charging pile, and can reduce costs at the same time .

The further technical task of the present invention is to provide a CP signal voltage detection device for an electric vehicle AC charging system.

To achieve the above object, the present invention provides the following technical solutions:

A method for detecting the CP signal voltage of an electric vehicle AC charging system, specifically comprising the following steps:

S1. Voltage comparison: the CP signal voltage value is compared with the set voltage value respectively, and the high level or low level is output by comparing the voltage values of the two;

S2. Isolated output: the high level or low level output in step S1 is converted into a CMOS level signal by an optocoupler, and input to the pins of the MCU respectively;

S3. Sampling calculation: read the pin level status through the MCU, and query to obtain the current voltage value.

Preferably, in step S1, the set voltage value is +2.5V, +6.5V, +10V, and when the CP signal voltage value is greater than the above-mentioned constant voltage value +2.5V, +6.5V, +10V, output a high level +15V , otherwise output low level 0V, get three level values.

Preferably, the three level values are converted into three CMOS level signals through an optocoupler, and the three CMOS level signals are input into three pins of the MCU.

As preferably, the sampling calculation in the step S3 includes: 1) three pin states of the configuration MCU are input states; 2) regularly read the input level states of the three pins; 3) filter the invalid level state; The average value combination judges the CP signal voltage value.

Preferably, when reading the input level states of the three pins regularly, when the pin level is high, it is recorded as 1, and when the pin level is low, it is recorded as 0.

Preferably, the state of filtering the invalid level is that the MCU continuously reads the levels of three pins at a certain frequency, and if the levels of the three pins are all low, it is an invalid level, then the invalid level is filtered.

Preferably, when filtering invalid levels, three pin levels are read every 500us.

A CP signal voltage detection device of an electric vehicle AC charging system, the device includes the following modules:

Voltage comparison module: responsible for comparing the CP signal voltage value with the set voltage value, and output high level or low level by comparing the voltage values of the two;

Isolated output module: responsible for converting the high level or low level output by the voltage comparison module into a CMOS level signal, and inputting the pins of the sampling calculation module respectively;

Sampling calculation module: responsible for querying the current voltage value by reading the pin level status.

Preferably, the voltage comparison module is three comparators, and the set voltage values are +2.5V, +6.5V, +10V. After comparison by the three comparators, the voltage value of the CP signal is greater than the above constant voltage value +2.5V , +6.5V, +10V, output high level +15V, otherwise output low level 0V, get three level values.

Preferably, the isolated output module is three optocouplers, the sampling calculation module is an MCU, the three level values are converted into three CMOS level signals through the optocoupler, and the three CMOS level signals are input to the three pin.

Among them, the MCU sampling calculation process includes:

1) Configure the three pin states of the MCU as input states;

2) Regularly read the input level status of the three pins. When reading the input level status of the three pins regularly, when the pin level is high, it is recorded as 1, and when the pin level is low, it is recorded as 0;

3) To filter the invalid level state, the MCU continuously reads the levels of three pins every 500us, if the levels of the three pins are all low, it is an invalid level, then filter the invalid level;

4) Judging the CP signal voltage value according to the level value combination.

Compared with the prior art, the CP signal voltage detection method of the electric vehicle AC charging system of the present invention has the following outstanding beneficial effects: the CP signal voltage detection method of the electric vehicle AC charging system is simple and easy to implement, and can improve the efficiency of the AC charging pile. Controlling the reliability of the guidance function while reducing costs, it has a wide range of application scenarios and has good promotion and application value.

Description of drawings

Fig. 1 is the flowchart of the CP signal voltage detection method of the electric vehicle AC charging system of the present invention;

Fig. 2 is a topological diagram of the CP signal voltage detection device of the electric vehicle AC charging system according to the present invention.

Detailed ways

The method and device for detecting the CP signal voltage of the electric vehicle AC charging system of the present invention will be further described in detail below in conjunction with the drawings and embodiments.

Example

The CP signal voltage detection method of the electric vehicle AC charging system of the present invention comprises the following steps:

S1. Voltage comparison: The voltage value of the CP signal is compared with the set voltage value, and a high level or a low level is output by comparing the voltage values of the two.

The set voltage value is +2.5V, +6.5V, +10V, when the CP signal voltage value is greater than the above constant voltage value +2.5V, +6.5V, +10V, output high level +15V, otherwise output low level 0V , to get three level values.

S2. Isolated output: the high level or low level output in step S1 is converted into a CMOS level signal by an optocoupler, and input to the pins of the MCU respectively.

The three level values are converted into three CMOS level signals by optocouplers, and the three CMOS level signals are input to three pins of the MCU.

S3. Sampling calculation: read the pin level status through the MCU, and query to obtain the current voltage value.

Sampling calculations include:

1) Configure the three pin states of the MCU as input states.

2) Read the input level status of the three pins at regular intervals. When the pin level is high, it is recorded as 1, and when the pin level is low, it is recorded as 0, thus obtaining a 3-bit binary number. For example, when the CP signal voltage value is DC9V, the output is 0V after comparison with +10V, the output is +15V after comparison with +6.5V, and the output is +15V after comparison with +2.5V. After the optocoupler isolation output, respectively 0V, +3.3V, +3.3V, the MCU reads the pin value as 011. Similarly, when the CP voltage is PWM9V, the CP signal voltage changes between 9V and 0V, and the pin level value read by the MCU is 011 or 000.

3) Filter invalid level status. The MCU continuously reads the levels of three pins every 500us. If the levels of the three pins are all low, that is, there is a value of 000, which is an invalid level, the invalid level is filtered.

4) Judging the CP signal voltage value according to the level value combination.

As shown in Figure 1 and Figure 2, the specific process is as follows:

1. The CP signal voltage value is input into comparator 1, comparator 2, and comparator 3 respectively, and compared with +2.5V, +6.5V, +10V voltage respectively. When it is greater than this voltage, it will output a high level +15V, which is less than this voltage. , output low level 0V.

2. The three level values are converted to +3.3V by optocoupler 1, optocoupler 2 and optocoupler 3, and 0V remains unchanged.

3. The MCU reads the level status of the three pins. The reading result of +3.3V is 1, and the reading result of 0V is 0. According to the sequence of comparison results of +10V, +6.5V, +2.5V, the current voltage is obtained Code value combinations: 000, 011, 001, 111.

4. Configure the three pins of the MCU as input state.

5. Read the input level status of the three pins every 500us to get the voltage code value.

6. If the code value is 000, discard it.

7. According to the effective voltage value code, look up the table to obtain the current CP signal voltage value, thereby judging the charging state, as shown in Table 1.

Table 1 Correspondence between pin level value and CP signal voltage value

level combination CP signal voltage charging 001 +6V The charging cable is plugged in and charging 011 +9V The charging cable has been plugged in, but charging has not started 111 +12V The charging cable is not plugged in

8. Other processes call the CP signal voltage value to judge the charging status.

As shown in Figure 2, the CP signal voltage detection device of the electric vehicle AC charging system of the present invention, the device includes the following modules:

Voltage comparison module: responsible for comparing the CP signal voltage value with the set voltage value, and output high level or low level by comparing the voltage values of the two.

The voltage comparison module is three comparators, and the set voltage values are +2.5V, +6.5V, +10V. After comparison by the three comparators, the voltage value of the CP signal is greater than the above constant voltage values +2.5V, +6.5V, When +10V, output high level +15V, otherwise output low level 0V, get three level values.

Isolated output module: responsible for converting the high level or low level output by the voltage comparison module into CMOS level signals, and inputting them into the pins of the sampling calculation module respectively.

The isolated output module is three optocouplers, and the sampling calculation module is an MCU. The three level values are converted into three CMOS level signals by the optocoupler, and the three CMOS level signals are input to three pins of the MCU.

Sampling calculation module: responsible for querying the current voltage value by reading the pin level status.

The MCU sampling calculation process includes:

1) Configure the three pin states of the MCU as input states;

2) Regularly read the input level status of the three pins. When reading the input level status of the three pins regularly, when the pin level is high, it is recorded as 1, and when the pin level is low, it is recorded as 0;

3) To filter the invalid level state, the MCU continuously reads the levels of three pins every 500us, if the levels of the three pins are all low, it is an invalid level, then filter the invalid level;

4) Judging the CP signal voltage value according to the level value combination.

The above-described embodiments are only preferred specific implementations of the present invention, and ordinary changes and replacements performed by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. a CP signal voltage detection method of electric vehicle AC charging system, is characterized in that: specifically comprise the following steps: S1. Voltage comparison: the CP signal voltage value is compared with the set voltage value respectively, and the high level or low level is output by comparing the voltage values of the two; S2. Isolated output: the high level or low level output in step S1 is converted into a CMOS level signal by an optocoupler, and input to the pins of the MCU respectively; S3. Sampling calculation: read the pin level status through the MCU, and query to obtain the current voltage value. 2. The CP signal voltage detection method of the electric vehicle AC charging system according to claim 1, characterized in that: in step S1, the set voltage value is +2.5V, +6.5V, +10V, and the CP signal voltage value is greater than When the above constant voltage values are +2.5V, +6.5V, +10V, output high level +15V, otherwise output low level 0V, and get three level values. 3. The CP signal voltage detection method of the electric vehicle AC charging system according to claim 2, characterized in that: the three level values are converted into three CMOS level signals through optocouplers, and the three CMOS level signals Enter the three pins of the MCU. 4. The CP signal voltage detection method of the electric vehicle AC charging system according to claim 3 is characterized in that: sampling calculation comprises in the step S3: 1) three pin states of configuration MCU are input state; 2) regularly read Take the input level status of the three pins; 3) filter the invalid level status; 4) judge the CP signal voltage value according to the level value combination. 5. The CP signal voltage detection method of the electric vehicle AC charging system according to claim 4, characterized in that: when reading the input level states of the three pins regularly, when the pin level is high, it is recorded as 1, When the pin level is low, it is recorded as 0. 6. The CP signal voltage detection method of the electric vehicle AC charging system according to claim 5, characterized in that: the filtering invalid level state is that the MCU continuously reads three pin levels at a certain frequency, if three When the pin levels are all low, it is an invalid level, and the invalid level is filtered. 7. The CP signal voltage detection method of the electric vehicle AC charging system according to claim 6, characterized in that: when filtering the invalid level, three pin levels are read every 500us. 8. A CP signal voltage detection device of an electric vehicle AC charging system, characterized in that: it comprises the following modules: Voltage comparison module: responsible for comparing the CP signal voltage value with the set voltage value, and output high level or low level by comparing the voltage values of the two; Isolated output module: responsible for converting the high level or low level output by the voltage comparison module into a CMOS level signal, and inputting the pins of the sampling calculation module respectively; Sampling calculation module: responsible for querying the current voltage value by reading the pin level status. 9. The CP signal voltage detection device of the electric vehicle AC charging system according to claim 8, characterized in that: the voltage comparison module is three comparators, and the set voltage values are +2.5V, +6.5V, + 10V, compared by three comparators, when the CP signal voltage value is greater than the above constant voltage value +2.5V, +6.5V, +10V, output high level +15V, otherwise output low level 0V, get three levels value. 10. The CP signal voltage detection device of the electric vehicle AC charging system according to claim 9, characterized in that: the isolated output module is three optocouplers, the sampling calculation module is an MCU, and the three level values are passed through The optocoupler is converted into three CMOS level signals, and the three CMOS level signals are input to the three pins of the MCU.