阅读说明：本技术 充电桩电源模块宽范围输出控制方法 (Charging pile power module wide-range output control method ) 是由 陈锐 龚戈峰 刘兆元 王红涛 谢银银 黄刚 于 2019-11-15 设计创作，主要内容包括：本发明公开了一种充电桩电源模块宽范围输出控制方法,要解决的技术问题是充电桩电源模块切换电压时连续输出功率。本发明的充电桩电源模块宽范围输出控制方法,包括高低电压切换的逻辑运算和继电器切换控制步骤,高低电压切换的逻辑运算,由设定电源模块的输出电压和逻辑运算两部分组成。本发明与现有技术相比,采用CPU控制电源模块采用高电压、低电压的输出模式,通过设定电源模块的输出电压,逻辑运算,CPU发出控制信号实现继电器1和继电器2之间的切换,不关断电源模块,实现无缝切换电源模块宽电压范围输出功率。(The invention discloses a wide-range output control method for a charging pile power supply module, and aims to solve the technical problem of continuously outputting power when the charging pile power supply module switches voltage. The wide-range output control method of the charging pile power module comprises the steps of high-low voltage switching logic operation and relay switching control, wherein the high-low voltage switching logic operation is composed of two parts of setting the output voltage of the power module and logic operation. Compared with the prior art, the invention adopts the CPU to control the power supply module to adopt the output mode of high voltage and low voltage, and the CPU sends out a control signal to realize the switching between the relay 1 and the relay 2 by setting the output voltage of the power supply module and logic operation, and the power supply module is not switched off, thereby realizing the seamless switching of the output power of the power supply module in a wide voltage range.)

1. A charging pile power module wide-range output control method comprises the steps of logic operation of high-voltage and low-voltage switching and relay switching control;

the logic operation of high-low voltage switching consists of setting the output voltage of a power supply module and performing logic operation;

the setting of the output voltage of the power supply module comprises the following steps:

(1) the CPU stores messages of the set charging voltage and the charging current sent by the charging pile monitoring device into a buffer area of the CPU, detects the messages, and calculates a difference value Verr between the current output voltage Vout and the set output voltage Vset of the power supply module, wherein the messages comprise the set charging voltage and the charging current:

Verr＝Vout-Vset；

(2) the CPU judges that the set charging voltage Vset in the set charging voltage and current message is within the range of DC 200-750V which can be output by the power module, and updates the set output voltage Vset to Vset;

(3) the CPU makes logic judgment

Judging that the updated set output voltage Vset, the current output voltage Vout and the current output voltage mode Mout satisfy the condition 1:

Vset>505V、Mout＝0、Vout<Vset，

judging that the Verr and the power module startup frequency meet the condition 5:

verr is more than 5V, the power supply module is started for the first time,

switching a power supply module to a high voltage mode for operation, setting an output voltage mode identifier Mout to be 1, turning off the power supply output of the power supply module, setting a soft start state identifier Stsoft to be 0x10, and setting a relay switching identifier RelayFlg to be 1;

the logic operation comprises the following steps:

(1) the CPU does not receive a set charging voltage and charging current message issued by the charging pile monitoring device;

(2) in the normal output voltage and current operation process, the using state identifier Stsoft of the power supply module is 0x03, and the CPU detects the change condition of the current output voltage Vout along with the external load;

(3) the CPU performs logic operation, and judges that the current output voltage Vout and the current output voltage mode Mout meet the condition 3:

Vout<495V、Mout＝1，

the CPU switches the power supply module to a low voltage mode to operate, sets an output voltage mode identifier Mout to be 0, turns off the power supply output of the power supply module, sets a soft start state identifier Stsoft to be 0x10, and sets a relay switching identifier RelayFlg to be 1;

second, relay switching control

CPU detects relay switching identification RelayFlg, and relay switching identification RelayFlg is 0, withdraws from the relay switching control flow, and CPU begins the next detection.

2. The charging pile power module wide-range output control method according to claim 1, characterized in that: and (2) detecting messages in the step (1) of setting the output voltage of the power supply module, wherein the CPU detects the messages once every 20 ms.

3. The charging pile power module wide-range output control method according to claim 2, characterized in that: and (2) in the step (1) of setting the output voltage of the power supply module, the CPU detects a message every 20ms, and the detection is finished if the charging voltage and the charging current message are not set.

4. The charging pile power module wide-range output control method according to claim 3, characterized in that: and (2) in the step of setting the output voltage of the power supply module, the CPU judges that the set charging voltage Vmset in the set charging voltage and current message is not in the range of DC 200-750V which can be output by the power supply module, and the detection is finished.

5. The charging pile power module wide-range output control method according to claim 4, characterized in that: and (3) setting the output voltage of the power supply module, judging that the Verr and the power supply module startup frequency do not meet a condition 5, and judging that the Verr meets a condition 6:

Verr≤5V，

the output voltage is set to be high voltage, the output voltage mode identifier Mout is set to be 1, the power supply output of the power supply module is turned off, the soft start state identifier Stsoft is set to be 0x10, and the relay switching identifier RelayFlg is set to be 1.

6. The charging pile power module wide-range output control method according to claim 5, characterized in that: and (3) setting the output voltage of the power supply module, judging that the Verr does not meet the condition 6, and finishing the detection.

7. The charging pile power module wide-range output control method according to claim 1, characterized in that: and (3) setting the output voltage of the power supply module, judging that the updated set output voltage Vset, the current output voltage Vout and the current output voltage mode Mout do not satisfy a condition 1, and judging that the set output voltage Vset and the current output voltage mode Mout satisfy a condition 2:

Vset<495V、Mout＝1，

the CPU switches the power supply module to a low voltage mode to operate, sets an output voltage mode identifier Mout to be 0, turns off the power supply output of the power supply module, sets a soft start state identifier Stsoft to be 0x10, and sets a relay switching identifier RelayFlg to be 1.

8. The charging pile power module wide-range output control method according to claim 7, characterized in that: and (3) setting the output voltage of the power supply module, judging that the set output voltage Vset and the current output voltage mode Mout do not meet the condition 2, and finishing the detection.

9. The charging pile power module wide-range output control method according to claim 1, characterized in that: in the logic operation step (2), the CPU detects the current output voltage Vout as the external load, and detects the current output voltage Vout once every 250ms, where the TimerFlg250ms is equal to 1.

10. The charging pile power module wide-range output control method according to claim 1, characterized in that: in the logical operation step (2), Stsoft ≠ 0x03 or TimerFlg250ms ≠ 1, which ends this detection.

11. The charging pile power module wide-range output control method according to claim 10, characterized in that: in the logic operation step (3), the CPU determines that the current output voltage Vout and the current output voltage pattern Mout do not satisfy the condition 3, and determines that the set output voltage Vset, the current output voltage Vout, and the current output voltage pattern Mout satisfy the condition 4:

Vout>505V、Mout＝0、Vout<Vset，

the CPU switches the power supply module to a high voltage mode to operate, sets an output voltage mode identifier Mout equal to 1, turns off the power supply output of the power supply module, sets a soft start state identifier Stsoft equal to 0x10, and sets a relay switching identifier RelayFlg equal to 1.

12. The charging pile power module wide-range output control method according to claim 11, characterized in that: and (3) in the logic operation step, the set output voltage Vset, the current output voltage Vout and the current output voltage mode Mout do not satisfy the condition 4, and the next logic operation is started.

13. The charging pile power module wide-range output control method according to claim 1, characterized in that: and in the relay switching control, the CPU detects the relay switching identifier RelayFlg once every 50 ms.

14. The charging pile power module wide-range output control method according to claim 1, characterized in that: in the relay switching control, the CPU detects that a relay switching identifier RelayFlg is 1, delays for 2s, then controls to disconnect the relay with high voltage and low voltage output, delays for 50ms, and closes the high voltage relay when an output voltage mode identifier Mout is 0; when the output voltage pattern Mout is 1, the low-voltage relay is closed, and the relay switching flag is set to RelayFlg as 0.

15. The charging pile power module wide-range output control method according to claim 14, characterized in that: and the Relay position which delays 2s time for outputting high voltage and low voltage is disconnected or delays for more than 50ms, and the next relay switching control is started.

Technical Field

The invention relates to a control method of a charging pile, in particular to a control method of output power of a power module of the charging pile.

Background

The charging pile power module (power module) is an indispensable core device of the direct-current charging pile and is used for completing the conversion between alternating current and direct current (AC)/DC of electric energy and providing an output power supply for the direct-current charging pile. Along with electric automobile and direct current fill electric pile's continuous growth, also constantly changing to the demand of charging voltage, the charging voltage of various direct current electric automobile that charges at present is between direct current DC200 ~ 1000V, in order to realize high-efficient, quick charging, it can both full load output power to require direct current to fill electric pile power module at the different output voltage stages in whole charging process, require power module to realize wide voltage range output maximum power promptly, guarantee under different output voltage condition or under most of the circumstances, output maximum power.

Taking a direct current charging pile power module with an output range of DC 200-750V as an example, in order to realize the output of the maximum power in a wide range, the general method is to set the direct current and direct current DC/DC output circuits of the power module as 2 paths, select the output circuit through a relay, set the output circuit within the range of DC 200-500V, close the relay 1, open the relay 2, select the output circuit 1 to output in a low-voltage mode, set the output circuit within the range of DC 500-750V, close the relay 2, open the relay 1, select the output circuit 2 to output in a high-voltage mode, so as to satisfy the maximum output power of each output voltage stage or partial stages in the charging process.

Disclosure of Invention

The invention aims to provide a charging pile power supply module wide-range output control method, and aims to solve the technical problem of continuously outputting power when a charging pile power supply module switches voltage.

The invention adopts the following technical scheme: a charging pile power module wide-range output control method comprises the steps of logic operation of high-voltage and low-voltage switching and relay switching control;

the logic operation of high-low voltage switching consists of setting the output voltage of a power supply module and performing logic operation;

the setting of the output voltage of the power supply module comprises the following steps:

(1) the CPU stores messages of the set charging voltage and the charging current sent by the charging pile monitoring device into a buffer area of the CPU, detects the messages, and calculates a difference value Verr between the current output voltage Vout and the set output voltage Vset of the power supply module, wherein the messages comprise the set charging voltage and the charging current:

Verr＝Vout-Vset；

(2) the CPU judges that the set charging voltage Vset in the set charging voltage and current message is within the range of DC 200-750V which can be output by the power module, and updates the set output voltage Vset to Vset;

(3) the CPU makes logic judgment

Judging that the updated set output voltage Vset, the current output voltage Vout and the current output voltage mode Mout satisfy the condition 1:

Vset>505V、Mout＝0、Vout<Vset，

judging that the Verr and the power module startup frequency meet the condition 5:

verr is more than 5V, the power supply module is started for the first time,

switching a power supply module to a high voltage mode for operation, setting an output voltage mode identifier Mout to be 1, turning off the power supply output of the power supply module, setting a soft start state identifier Stsoft to be 0x10, and setting a relay switching identifier RelayFlg to be 1;

the logic operation comprises the following steps:

(1) the CPU does not receive a set charging voltage and charging current message issued by the charging pile monitoring device;

(2) in the normal output voltage and current operation process, the using state identifier Stsoft of the power supply module is 0x03, and the CPU detects the change condition of the current output voltage Vout along with the external load;

(3) the CPU performs logic operation, and judges that the current output voltage Vout and the current output voltage mode Mout meet the condition 3:

Vout<495V、Mout＝1，

the CPU switches the power supply module to a low voltage mode to operate, sets an output voltage mode identifier Mout to be 0, turns off the power supply output of the power supply module, sets a soft start state identifier Stsoft to be 0x10, and sets a relay switching identifier RelayFlg to be 1;

second, relay switching control

CPU detects relay switching identification RelayFlg, and relay switching identification RelayFlg is 0, withdraws from the relay switching control flow, and CPU begins the next detection.

In the step (1) of setting the output voltage of the power supply module, the message is detected, and the CPU detects the message once every 20 ms.

In the step (1) of setting the output voltage of the power supply module, the CPU detects a message every 20ms, and a charging voltage message and a charging current message are not set, so that the detection is finished.

In the step (2) of setting the output voltage of the power supply module, the CPU judges that the set charging voltage Vmset in the set charging voltage and current message is not in the range of DC 200-750V which can be output by the power supply module, and ends the detection.

In the step (3) of setting the output voltage of the power supply module, the Verr and the power supply module startup frequency are judged to not meet the condition 5, and the Verr is judged to meet the condition 6:

Verr≤5V，

the output voltage is set to be high voltage, the output voltage mode identifier Mout is set to be 1, the power supply output of the power supply module is turned off, the soft start state identifier Stsoft is set to be 0x10, and the relay switching identifier RelayFlg is set to be 1.

And (3) setting the output voltage of the power supply module, judging that the Verr does not meet the condition 6, and finishing the detection.

In the step (3) of setting the output voltage of the power supply module, it is determined that the updated set output voltage Vset, the current output voltage Vout, and the current output voltage pattern Mout do not satisfy the condition 1, and it is determined that the set output voltage Vset and the current output voltage pattern Mout satisfy the condition 2:

Vset<495V、Mout＝1，

the CPU switches the power supply module to a low voltage mode to operate, sets an output voltage mode identifier Mout to be 0, turns off the power supply output of the power supply module, sets a soft start state identifier Stsoft to be 0x10, and sets a relay switching identifier RelayFlg to be 1.

In the step (3) of setting the output voltage of the power module, the set output voltage Vset and the current output voltage mode Mout are judged not to satisfy the condition 2, and the detection is finished.

In the logic operation step (2), the CPU detects the change of the current output voltage Vout along with the external load, and the detection is carried out once every 250ms, and the TimerFlg250ms is 1.

In the logical operation step (2), Stsoft ≠ 0x03 or TimerFlg250ms ≠ 1, which concludes this detection.

In the logic operation step (3), the CPU determines that the current output voltage Vout and the current output voltage pattern Mout do not satisfy the condition 3, and determines that the set output voltage Vset, the current output voltage Vout, and the current output voltage pattern Mout satisfy the condition 4:

Vout>505V、Mout＝0、Vout<Vset，

the CPU switches the power supply module to a high voltage mode to operate, sets an output voltage mode identifier Mout equal to 1, turns off the power supply output of the power supply module, sets a soft start state identifier Stsoft equal to 0x10, and sets a relay switching identifier RelayFlg equal to 1.

In the logic operation step (3), the set output voltage Vset, the current output voltage Vout and the current output voltage mode Mout do not satisfy the condition 4, and the next logic operation is started.

According to the relay switching control, the CPU detects the relay switching identification RelayFlg once every 50 ms.

According to the relay switching control, a CPU detects that a relay switching identifier RelayFlg is 1, delays for 2s, then controls to disconnect a relay with high voltage and low voltage output, delays for 50ms, and closes the high voltage relay when an output voltage mode identifier Mout is 0; when the output voltage pattern Mout is 1, the low-voltage relay is closed, and the relay switching flag is set to RelayFlg as 0.

The Relay switching control method has the advantages that the Relay Flg is not equal to 1, the relay position of high-voltage and low-voltage output is disconnected after 2s of time delay, or the relay position is delayed for more than 50ms, and the next relay switching control is started.

Compared with the prior art, the invention adopts the CPU to control the power supply module to adopt the output mode of high voltage and low voltage, and the CPU sends out a control signal to realize the switching between the relay 1 and the relay 2 by setting the output voltage of the power supply module and logic operation, and the power supply module is not switched off, thereby realizing the seamless switching of the output power of the power supply module in a wide voltage range.

Drawings

FIG. 1 is a flow chart of the method of setting the output voltage of the power module according to the present invention.

FIG. 2 is a flow chart of the logic operation of the method of the present invention for high and low voltage switching.

Fig. 3 is a flow chart of the method relay switching control of the present invention.

Fig. 4 is a block diagram of a power module architecture employed by the method of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. The charging pile power module wide-range output control method (method) is used for controlling the output power of the charging pile power module to an electric vehicle within the DC 220-750V voltage range, and when the power module outputs power, the power module is switched to output low voltage without power failure relative to the output high voltage or is switched to high voltage uninterruptedly relative to the output low voltage within the DC 220-750V voltage range, so that the power module can realize the power-off switching (seamless switching) of the output voltage when outputting power.

As shown in fig. 4, before charging the electric vehicle, the method of the present invention first uses a Controller Area Network (CAN) bus 2 to establish a communication connection between a dc charging pile monitoring device (charging pile monitoring device) and a battery management system BMS of the electric vehicle, the charging pile monitoring device communicates with a CPU of a power module through a CAN bus 1, a dc output terminal of the power module outputs a dc power to a charging gun of the charging pile, and an output cable of the charging gun is connected to a battery system of the electric vehicle to charge a battery of the electric vehicle.

An alternating current power supply is input from an alternating current input terminal of the power supply module and is connected to a direct current output terminal through an alternating current and direct current AC/DC modulation circuit, a direct current and direct current DC/DC modulation circuit and a relay. The CPU of the power module controls the output power of the AC/DC and DC/DC modulation circuits by modulating PWM waves through pulse width, the DC/DC modulation circuits respectively output two paths of direct currents of high voltage and low voltage, the direct currents respectively pass through a relay 1 of high voltage output and a relay 2 of low voltage output to a direct current output terminal, and the CPU respectively outputs control signals through two input/output IO pins on the CPU to control the on/off of the relay 1 and the relay 2.

In this embodiment, the CPU uses a combination of C language and assembly language to implement the logical operation and logical control of the method of the present invention. In the process of operation and control,

the output voltage mode adopts an identifier Mout, the low voltage mode Mout is 0, the high voltage mode Mout is 1, and when the software is started, the initialization Mout is 0.

The relay switching operation requirement adopts an identifier RelayFlg, the switching operation RelayFlg is not required to be 0, the switching operation RelayFlg is required to be 1, and the initialization RelayFlg is 0 during soft start.

The soft start of the power module refers to a power module state jump process from power-on to charging of the electric automobile, and the power module has five states in the whole process of starting, standby, charging and shutdown: initial, condition judgment, boosting stage, normal operation and shutdown.

The soft start state of the power module adopts a mark Stsoft. The soft start initial state Stsoft is 0x00, the soft start condition determination state Stsoft is 0x01, the soft start boost phase Stsoft is 0x02, the normal operation state Stsoft is 0x03, and the soft start shutdown state Stsoft is 0x 10. At soft start, Stsoft ═ 0x00 is initialized. The soft start state jump process is as follows, when the state Stsoft ═ 0x00, the variable is initialized, and then the state Stsoft ═ 0x01 is set; when the status Stsoft is 0x01, judging the abnormal status of the module such as over temperature, over voltage, over current and fan, if there is no abnormality, closing the soft start relay, and setting Stsoft to 0x 02; when the state Stsoft is 0x02, starting the PWM wave, raising the output voltage to the required voltage value, and then setting Stsoft to 0x 03; the state Stsoft ═ 0x03 is the normal operation state of the module, the logic calculation of high-low voltage switching, the relay switching control and the abnormal judgment of the module operation are carried out in the state, if the high-low voltage switching occurs, the state jumps to the state Stsoft ═ 0x10, if the module has over-temperature, over-voltage, over-current and abnormal fan, the state also jumps to the state Stsoft ═ 0x 10; when the state Stsoft is 0x10, the PWM wave output is turned off, the soft start relay is turned off, and after 100ms delay, the state jumps to the state Stsoft of 0x00, and the normal output voltage and current operation Stsoft of 0x 03.

The timing mark adopts TimerFlg (the time is marked for 250ms later), when software is started, the TimerFlg is initialized to be 0, when a timer counter counts for 250ms, the TimerFlg is set to be 1, then in the logic operation, after a processing flow is entered, the TimerFlg is set to be 0, and the TimerFlg + marked time is set to be 1.

The method comprises the steps of logic operation of high-voltage and low-voltage switching and relay switching control.

Logic operation of one, high and low voltage switching

The logic operation of switching the high voltage and the low voltage output by the power supply module consists of setting the output voltage of the power supply module and the logic operation.

1. After the charging pile monitoring device is communicated with a battery management system BMS of the electric automobile, a message of 'setting charging voltage and charging current' is sent to a power supply module according to the charging voltage and the charging current required by the BMS. And the CPU of the power supply module performs logic judgment according to the received message of 'setting charging voltage and charging current' by combining the current power supply module running state and the current power supply module actual output voltage (current output voltage Vout), and sets the output voltage of the power supply module.

The power module running state refers to the state that the power module is in shutdown, startup, charging work to the electric automobile and relay switching, and comprises a power module soft start state Stsoft start, a relay switching RelayFlg, an output voltage mode Mout and a timing mark TimerFlg (250 ms).

In order to ensure that the output power of each output voltage stage is maximum in the charging process, when the set charging voltage of the power module is within a range of DC 200-500V, the output is in a low-voltage mode, when the set charging voltage is within a range of DC 500-750V, the output is in a high-voltage mode, a demarcation point between the high-voltage mode and the low-voltage mode is 500V, in order to avoid frequent switching of the relay 1 and the relay 2, when the CPU controls the relay 1 and the relay 2 to be closed or opened, the DC 495-505V is set as a voltage switching dead zone, when the CPU performs logic judgment, two demarcation points of the output voltage are respectively 495V and 505V, and when the high-voltage mode is switched to the low-voltage mode, the 495V is used as a switching threshold value (condition 2 and condition 3 described later); when switching from the low-pressure mode to the high-pressure mode, 505V is used as a switching threshold value (conditions 1 and 4 described later).

As shown in fig. 1, the setting of the output voltage of the power module includes the following steps:

(1) and the CPU stores the message of the 'set charging voltage and charging current' sent by the charging pile monitoring device into a buffer area of the CPU. The CPU detects the message in the buffer area once every 20ms, and if a 'set charging voltage and charging current' message issued by the charging pile monitoring device is received, a difference value Verr between the current output voltage Vout and the set output voltage Vset of the power supply module is calculated:

Verr＝Vout-Vset (1)

the CPU of the power supply module collects the current output voltage Vout of the direct current output terminal through a self-contained 12-bit analog-to-digital converter ADC.

If the CPU does not receive the message of 'setting charging voltage and charging current' sent by the charging pile monitoring device, the step (detection) of setting the output voltage of the power supply module is finished, and the next detection is started.

(2) The CPU judges whether the set charging voltage in the message of 'set charging voltage and current' issued by the charging pile monitoring device is reasonable, namely whether the set charging voltage Vmset is within the range of DC 200-750V which can be output by the power module, and if the set charging voltage Vmset is within the range which can be output by the power module, the set output voltage Vset is updated to be Vmset.

If the value of the set output voltage is not reasonable, the Vmset is not within the range of DC 200-750V which can be output by the power supply module, the detection is finished, and the next detection is started.

(3) The CPU makes logic judgment

Judging whether the updated set output voltage Vset, the current output voltage Vout and the current output voltage mode Mout satisfy the condition 1:

Vset>505V、Mout＝0、Vout<Vset。

the initial Mout is 0 when the software is started. And Mout is 0, which indicates that the power supply module originally operates in the low-voltage mode.

If the condition 1 is met, judging whether the Verr and the power module starting frequency obtained in the formula (1) meet the condition 5:

verr is more than 5V, and the power supply module is started for the first time.

The first startup of the power supply module means that the charging pile monitoring device performs output startup operation on the power supply module for the first time after the power supply module is powered on this time.

And 5V in Verr >5V is a reasonable threshold value obtained in the test, before the power supply module is started for the first time, the power supply module does not output voltage, the difference value between the calculated output voltage and the set output voltage is greater than 5V, and if the difference value is less than or equal to 5V, the output voltage Vout obtained by sampling is abnormal.

The CPU is logically judged to simultaneously meet the conditions 1 and 5, the power supply module is switched to a high-voltage mode to operate, an output voltage mode identifier Mout is set to be 1, the DC/DC modulation circuit is closed by closing an output PWM wave, the power supply output to the power supply module is cut off, after the power supply output of the power supply module is cut off, the jump of a soft start state is carried out, a soft start state identifier Stsoft is set to be 0x10, the relay switching operation is prepared, and a relay switching identifier RelayFlg is set to be 1.

If the condition 5 is not satisfied, judging whether the Verr obtained in the formula (1) satisfies the condition 6:

Verr≤5V。

if condition 6 is satisfied, the output voltage is set to a high voltage. The CPU switches the power module to a high voltage mode to operate, sets an output voltage mode identifier Mout to be 1, simultaneously closes the DC/DC modulation circuit by closing an output PWM wave, jumps in a soft start state after the power output of the power module is turned off, sets a soft start state identifier Stsoft to be 0x10, prepares to perform relay switching operation, and sets a relay switching identifier Relay to be 1.

If the condition 6 is not satisfied, the detection is finished, and the next detection is started.

If the condition 1 is not satisfied, whether the set output voltage Vset and the current output voltage mode Mout satisfy the condition 2 is judged:

Vset<495V、Mout＝1。

if the condition 2 is met, and Mout is equal to 1 in the condition 2, it indicates that the power supply module originally operates in the high-voltage mode. The output voltage is set to be low voltage, the CPU switches the power supply module to the low voltage mode to operate, the output voltage mode identification Mout is set to be 0, the DC/DC modulation circuit is closed by closing the output PWM wave, the jump of the soft start state is carried out after the power supply output of the power supply module is cut off, the soft start state identification Stsoft is set to be 0x10, the relay switching operation is prepared, and the relay switching identification RelayFlg is set to be 1.

If the condition 2 is not satisfied, the detection is finished, and the next detection is started.

2. In the operation process of the power supply module, the connected external load changes, so that the actual output voltage of the current power supply module also changes, and the CPU performs logic operation in real time according to the current operation state and the current output voltage of the current power supply module.

As shown in fig. 2, the logical operation includes the following steps:

(1) the CPU does not receive the message of 'setting charging voltage and charging current' sent by the charging pile monitoring device.

(2) After the electric automobile is charged by starting, in the process of normal output power supply (voltage and current) operation, the use state identifier Stsoft of the power supply module is 0x03, the CPU detects the change condition of the current output voltage Vout along with the external load once every 250ms, and the TimerFlg is 1.

If Stsoft ≠ 0x03 or TimeFlg ≠ 1, the logic operation (detection) is ended, and the next detection is started.

(3) The CPU performs logic operation, and judges whether the current output voltage Vout and the current output voltage mode Mout meet the condition 3:

Vout<495V、Mout＝1。

if the condition 3 is met, the power module is indicated to originally operate in a high-voltage mode, and the current output voltage is pulled down to a low-voltage section due to the change of the external load, so that the power module needs to be switched to a low-voltage mode to operate. The CPU switches the power module to a low voltage mode to operate, sets an output voltage mode identifier Mout to be 0, closes the DC/DC modulation circuit by closing an output PWM wave, jumps in a soft start state after the power output of the power module is turned off, sets a soft start state identifier Stsoft to be 0x10, prepares to perform relay switching operation, and sets a relay switching identifier Relay to be 1.

If the condition 3 is not satisfied, whether the set output voltage Vset, the current output voltage Vout, and the current output voltage mode Mout satisfy the condition 4 is continuously determined:

Vout>505V、Mout＝0、Vout<Vset。

if the condition 4 is met, the power module is indicated to be operated in a low-voltage mode originally, and the current output voltage is changed to a high-voltage section due to the change of the external load, so that the power module needs to be switched to a high-voltage mode to operate. The CPU switches the power module to a high voltage mode to operate, sets an output voltage mode identifier Mout to be 1, closes the DC/DC modulation circuit by closing an output PWM wave, jumps in a soft start state after the power output of the power module is turned off, sets a soft start state identifier Stsoft to be 0x10, prepares to perform relay switching operation, and sets a relay switching identifier Relay to be 1.

If the condition 4 is not satisfied, the next logical operation is started.

Second, relay switching control

As shown in fig. 3, the relay switching control comprises the following steps:

the CPU detects the relay switching flag RelayFlg once every 50 ms. If the relay switching identifier RelayFlg is 0, the relay 1 and the relay 2 in the high-voltage and low-voltage output mode controlled by the power supply module do not need to be switched, the relay switching control process is quitted, and the CPU starts the next detection.

If the CPU detects that the relay switching flag RelayFlg is 1, delay is performed for 2s (delay time 1), then the relay 1 for high voltage output and the relay 2 for low voltage output are controlled to be turned off, delay is performed for 50ms (delay time 2), switching control between the relay 1 and the relay 2 is performed according to the output voltage pattern flag Mout, and when the CPU determines that the output voltage pattern flag Mout is 0, the relay 1 is closed. When the CPU judges that the output voltage pattern Mout is 1, the relay 2 is closed. After switching, the CPU sets the relay switching identifier to 0.

And if the Relay which delays for 2s time and outputs high voltage and low voltage is not disconnected or delays for more than 50ms, the relay switching control for the next time is started.

In the method, a CPU of a power supply module of the direct current charging pile performs logical operation and logical judgment according to a set charging voltage and charging current message, the running state of the power supply module and the actual output voltage of the power supply module, which are sent by a current charging pile monitoring device, selects a corresponding output voltage mode, or the original output voltage mode is kept unchanged, the power supply module is controlled to adopt the output mode of high voltage and low voltage, through setting the output voltage of the power supply module and logic operation, the CPU sends out a control signal to realize the switching between the relay 1 and the relay 2, the power supply module is not switched off, the seamless switching of the wide voltage range output power of the power supply module is realized, and a voltage switching dead zone is arranged to avoid frequent switching of the relay, so that the problem that seamless switching of output voltage in the whole charging process cannot be realized due to control of output voltage of a DC 220-750V wide-range power module is solved.