Power-off control optimization circuit for relay

Abstract

The invention discloses a power-off control optimization circuit for a relay, and relates to the technical field of relay control circuits. The first processing module comprises an output circuit unit, an input circuit unit and a built-in CPU control unit. The CPU control unit is used for performing communication and data acquisition to realize a charging function, and specifically comprises a current sampling unit, a battery voltage unit, a guide voltage unit, an integration unit and a communication unit; the output circuit unit and the input circuit unit are electrically connected, the output circuit unit and the input circuit unit are electrically connected with the CPU control unit, integration of a plurality of functional modules is achieved, production, installation and debugging of a pile enterprise are facilitated, meanwhile, an onboard measurement function can be achieved, charging can be rapidly cut off, the cost of the pile enterprise is saved, and the cost of the pile enterprise is reduced. All components are integrated, and the function of safe charging is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of relay control circuits, and specifically to an optimized power-off control circuit for a relay. Background Art

[0002] During the DC charging process of a vehicle and a charging pile, when charging is abnormal, it takes time for the DC contactor to disconnect, generally between 10 ms and 30 ms. In the time period of the ms level, abnormal conditions will cause more damage to the vehicle and the pile. At the same time, the DC contactor has a large volume and is not convenient for board card integration. Although the common magnetic latching relay is convenient for board card integration and has the advantage of small volume, the magnetic latching relay cannot achieve the function of suddenly disconnecting under high voltage and large current conditions, and it needs to step down the voltage or reduce the current to safely disconnect. The whole process takes a long time and is not conducive to the rapid protection of the vehicle and the pile. Summary of the Invention

[0003] The purpose of the present invention is to provide an optimized power-off control circuit for a relay to solve the problems raised in the prior art.

[0004] To achieve the above purpose, the present invention provides the following technical solution: An optimized power-off control circuit for a relay, including a first processing module; The first processing module includes an output circuit unit, an input circuit unit, and a built-in CPU control unit; The output circuit unit is used to control the conduction and cutoff of the internal components of the output circuit, and maintain a path with the external voltage and the external indicating component; the input circuit unit is externally connected to the voltage through a switch. When the voltage exists, a loop is formed through a resistor and an optocoupler to ensure that the GPIO port of the microprocessor collects a high level. When the voltage does not exist, the loop cannot be formed, and it is ensured that the GPIO port of the microprocessor collects a low level through a pull-down resistor; The CPU control unit is used for communication and data acquisition to achieve the charging function, and specifically includes a current sampling unit, a battery voltage unit, a pilot voltage unit, an integration unit, and a communication unit; The output circuit unit is electrically connected to the input circuit unit, and the output circuit unit and the input circuit unit are respectively electrically connected to the CPU control unit.

[0005] According to the above technical solution, the output circuit unit includes a triode output circuit unit and a relay output circuit unit; The relay output circuit unit outputs high and low levels based on the GPIO port of the microprocessor to control the conduction and cutoff of the triode. The triode is paired with the relay, and the relay is controlled through the change of the base level. The output end of the relay forms the functions of conduction and cutoff; the triode output circuit unit is used to form a path with the external voltage and the external indicating element to control the lighting and extinguishing of the external indicating element.

[0006] According to the above technical solution, the current sampling unit includes: A sampling resistor is constructed, and the current passing through the sampling resistor is converted into a voltage according to Ohm's law for current acquisition. After filtering by inductance and capacitance, TVS is used for protection, and an operational amplifier circuit is used for amplification processing; A follower circuit is constructed, and the voltage followed by the follower circuit is processed in two directions. One of them outputs a differential signal through the isolation operational amplifier HCPL7840, and after being processed by the operational amplifier chip, it is output to the ADC port of the microprocessor for software processing; the other is processed by the operational amplifier chip to output a voltage signal. The comparator voltage is set, and the output voltage signal is compared with the comparator voltage. If the output voltage signal is higher than the comparator voltage signal, the comparator outputs a high voltage to turn on the field effect transistor, the optocoupler operates, the optocoupler outputs a high voltage, and when the hardware receives the high voltage output by the optocoupler, it judges that the output is overcurrent and performs protection.

[0007] According to the above technical solution, the battery voltage unit includes: During the charging process, the direct current output by the charging module is collected. The voltage is reduced to the range collected by the chip by using the method of resistor voltage division. TVS and inductance are added at the input end for protection and anti-interference ability. The isolation operational amplifier HCPL7840 is used for fixed amplification to output a differential signal, and the differential signal is output to the ADC port of the microprocessor through bias voltage and operational amplifier processing; In the battery voltage acquisition, by means of an unbalanced bridge, the relay is used to change the resistance between the positive and negative terminals of the battery voltage and the protective ground wire PE terminal; the insulation resistance value between the battery voltage and the ground is calculated, and the high and low levels of the GPIO port of the microprocessor control the isolation optocoupler to disconnect and close the relay.

[0008] According to the above technical solution, the guiding voltage unit includes: Judge the connection state between the voltage generated by the controller and the charging gun line, obtain the feedback of the plugging signal, and output it to the ADC acquisition port of the microprocessor through resistor voltage division and the processing of the operational amplifier chip, and process the signal state through software.

[0009] According to the above technical solution, the integration unit includes MOS transistors and magnetic latching relays; The integration of the K1K2 functions of the charging pile is realized through the GPIO port of the microprocessor. First, the 3.3V voltage is converted into a 5V level through a level converter. When the voltage of the GPIO port is high, after level conversion, it is input to the dual-channel precision monostable multivibrator and the RC delay circuit; The RC delay circuit outputs a driving signal to the MOS transistor, and the dual-channel precision monostable multivibrator outputs a signal to the magnetic latching relay to drive the magnetic latching relay to act. The dual-channel precision monostable multivibrator ensures the output of pulse signals DOUTA and DOUTB through the peripheral circuit and capacitor; after DOUTB passes through a delay circuit and a comparator, K-DOUTB is output. When the dual-channel precision monostable multivibrator inputs a high level, DOUTA and K-DOUTB output a pulse output logic with DOUTA high and K-DOUTB low. When the dual-channel precision monostable multivibrator inputs a low level, DOUTA and K-DOUTB output a pulse output logic level with DOUTA low and K-DOUTB high, ensuring the closing and opening of the magnetic latching relay.

[0010] According to the above technical solution, it further includes: The driving signal output by the RC delay circuit to the MOS transistor passes through a fast discharge and capacitor charging delay circuit, which is staggered from the control time of the magnetic latching relay; When the GPIO port of the microprocessor inputs a high level, the magnetic latching relay closes first, and the MOS transistor closes after 500ms; when the GPIO port of the microprocessor inputs a low level, the MOS transistor disconnects first, and the magnetic latching relay disconnects; An overcurrent signal is set to participate in controlling the disconnection of the MOS transistor. When the signal of the MOS transistor is high and the overcurrent signal does not exist, the MOS can be normally driven; when the signal of the MOS transistor is low and the overcurrent signal does not exist, the MOS can be normally turned off; when the overcurrent signal exists, regardless of whether the signal of the MOS transistor is high or low, the MOS cannot be closed.

[0011] According to the above technical solution, it further includes the driving of the magnetic latching relay: The driving of the relay uses a driving chip to ensure the closing and opening of the magnetic latching relay by inputting the high and low levels of DOUTA and K-DOUTB. Specifically, it includes: At the power supply of the chip, two high-voltage MOS transistors are placed at the front end, and two magnetic latching relays are placed at the rear end. The magnetic latching relay is disconnected under high voltage and large current conditions through control logic. A resistor and a capacitor are placed between the input DC positive and negative to ensure the stability of the voltage at the input end of the MOS transistor without abnormal fluctuations. TVS and resistors are set at both ends of the MOS transistor to protect it when the charging and disconnection instants of the MOS transistor exceed the rated parameters of the device.

[0012] According to the above technical solution, the communication unit includes: Adopt CAN communication, isolate and communicate through an isolated CAN chip, add TVS, gas discharge tube and self - restoring fuse at the output end for protection, and add common - mode inductor and RC circuit for anti - interference at the same time to realize information interaction between the vehicle end and the board.

[0013] Compared with the prior art, the beneficial effects of the present invention are: In the design of the present invention, during the low - power charging process, the integration of multiple functional modules is realized, which is convenient for pile enterprises to produce, install and debug; at the same time, the disadvantages of the magnetic latching relay are solved, and the charging can be quickly disconnected to protect the charging pile and the electric vehicle. The board has a high integration level. Except for the necessary modules and switching power supply, all other components can be integrated, achieving the function of safe charging; it can have on - board measurement function, quickly disconnect the charging, and save the cost of pile enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of module connection of an optimized circuit for power - off control of a relay according to the present invention; Figure 2 It is a schematic diagram of a triode output circuit unit of an optimized circuit for power - off control of a relay according to the present invention; Figure 3 It is a schematic diagram of a relay output circuit unit of an optimized circuit for power - off control of a relay according to the present invention; Figure 4 It is a schematic diagram of an input circuit unit of an optimized circuit for power - off control of a relay according to the present invention; Figure 5 It is a schematic diagram of a current sampling unit of an optimized circuit for power - off control of a relay according to the present invention; Figure 6 It is a schematic diagram of a battery voltage unit of an optimized circuit for power - off control of a relay according to the present invention; Figure 7 It is a schematic diagram of the control of the opening and closing of a relay in an optimized circuit for power - off control of a relay according to the present invention; Figure 8 It is a schematic diagram of a pilot voltage unit of an optimized circuit for power - off control of a relay according to the present invention; Figure 9 It is a schematic diagram of over - current signal triggering of an optimized circuit for power - off control of a relay according to the present invention; Figure 10 It is a schematic diagram of MOS - tube signal control logic of an optimized circuit for power - off control of a relay according to the present invention; Figure 11This is a drive control schematic diagram of a magnetic latching relay for an optimized power-off control circuit of a relay according to the present invention. Detailed implementation manners

[0015] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0016] In a specific embodiment of the present invention, an optimized power-off control circuit for a relay is provided, which includes a first processing module; As Figure 1 shown, the first processing module includes an output circuit unit, an input circuit unit, and a built-in CPU control unit; The output circuit unit is used to control the conduction and cut-off of the internal components of the output circuit, and maintain a path with the external voltage and the external indicating component; the input circuit unit is externally connected to the voltage through a switch. When the voltage exists, a loop is formed through a resistor and an optocoupler to ensure that the GPIO port of the microprocessor collects a high level; when the voltage does not exist, a loop cannot be formed to ensure that the GPIO port of the microprocessor collects a low level through a pull-down resistor. The CPU control unit is used for communication and data acquisition, and realizes the charging function, specifically including a current sampling unit, a battery voltage unit, a pilot voltage unit, an integration unit, and a communication unit; The output circuit unit is electrically connected to the input circuit unit, and the output circuit unit and the input circuit unit are respectively electrically connected to the CPU control unit.

[0017] The output circuit unit includes a triode output circuit unit and a relay output circuit unit; The relay output circuit unit outputs high and low levels based on the GPIO port of the microprocessor to control the conduction and cut-off of the triode. The triode is paired with the relay, and the relay is controlled through the change of the base level. The output end of the relay forms the functions of conduction and cut-off; the triode output circuit unit is used to form a path with the external voltage and the external indicating component to control the lighting and extinguishing of the external indicating component.

[0018] As Figure 2 shown, the triode output circuit unit includes a resistor R195, a transistor Q23, a diode D54, and a fuse F2; One end of the resistor R195 is electrically connected to the pin 85 of the control chip U2; As Figure 3As shown, the relay output circuit unit includes resistor R10, transistor Q1, diode D2, and relay K1; One end of the resistor R10 is electrically connected to pin 47 of the control chip U2.

[0019] As Figure 4 shown, the input circuit unit includes resistor R153, resistor R161, resistor R169, resistor R170, diode D34, and optocoupler B5; The resistor R169 is electrically connected to pin 141 of the control chip U2 According to the above technical solution, the current sampling unit includes: As Figure 5 shown, a sampling resistor is constructed, and the current passing through the sampling resistor is converted into a voltage according to Ohm's law for current acquisition. After filtering by inductance and capacitance, TVS is used for protection, and an operational amplifier circuit is used for amplification processing; A follower circuit is constructed, and the voltage followed by the follower circuit is processed in two directions. One of them outputs a differential signal through the isolation operational amplifier HCPL7840, and after being processed by the operational amplifier chip, it is output to the ADC port of the microprocessor for software processing; the other is processed by the operational amplifier chip to output a voltage signal. The comparator voltage is set, and the output voltage signal is compared with the comparator voltage. If the output voltage signal is higher than the comparator voltage signal, the comparator outputs a high voltage to turn on the field effect transistor, the optocoupler operates, the optocoupler outputs a high voltage, and when the hardware receives the high voltage output by the optocoupler, it judges that overcurrent occurs and performs protection.

[0020] According to the above technical solution, the battery voltage unit includes: As Figure 6 shown, during the charging process, the direct current output by the charging module is collected, and the voltage is reduced to the range that can be collected by the chip by using the method of resistor voltage division. As Figure 6 in resistors R50 to R76, TVS and inductance are added at the input end for protection and anti-interference ability. The isolation operational amplifier HCPL7840 is used for fixed amplification to output a differential signal, and the differential signal is output to the ADC port of the microprocessor through bias voltage and operational amplifier processing; In the battery voltage acquisition, by means of an unbalanced bridge, as Figure 7 shown, the relay is used to change the resistance between the positive and negative terminals of the battery voltage and the protective ground wire PE terminal; calculate the insulation resistance value between the battery voltage and the ground, and the high and low levels of the GPIO port of the microprocessor control the isolation optocoupler (TLP785GB) to disconnect and close the relay.

[0021] According to the above technical solution, the pilot voltage unit includes: As Figure 8As shown, the connection status between the voltage generated by the controller and the charging gun line is determined, the feedback of the plug-in signal is obtained, and the output is sent to the ADC acquisition port of the microprocessor through resistor voltage division and processing of the op amp chip, and the signal status is processed by software.

[0022] According to the above technical solution, the integrated unit includes a MOS tube and a magnetic latching relay; The charging pile integrated K1K2 function is realized through the GPIO port of the microprocessor. First, the 3.3V voltage is converted to a 5V level through the level conversion. When the GPIO port voltage is at a high level, after the level conversion, it is input into the dual-channel precision monostable multivibrator and RC delay circuit; The RC delay circuit outputs a driving signal to the MOS tube, and the dual-channel precision monostable multivibrator outputs a signal to the magnetic latching relay to drive the magnetic latching relay to operate. The dual-channel precision monostable multivibrator ensures the output of pulse signals: DOUTA and DOUTB through peripheral circuits and capacitors; after DOUTB passes through a delay circuit and a comparator, it outputs K-DOUTB. When the dual-channel precision monostable multivibrator inputs a high level, DOUTA and K-DOUTB output a pulse output logic level of DOUTA high and K-DOUTB low. When the dual-channel precision monostable multivibrator inputs a low level, DOUTA and K-DOUTB output a pulse output logic level of DOUTA low and K-DOUTB high, thereby ensuring the closing and opening of the magnetic latching relay.

[0023] According to the above technical solution, it also includes: The driving signal output by the RC delay circuit to the MOS tube passes through a fast discharge and capacitor charging delay circuit, which is staggered with the control time of the magnetic latching relay; When the GPIO port of the microprocessor inputs a high level, the magnetic latching relay closes first, and the MOS tube closes after 500ms; when the GPIO port of the microprocessor inputs a low level, the MOS tube opens first, and the magnetic latching relay opens; Set the overcurrent signal to control the disconnection of the MOS tube, such as Figure 9 As shown, the overcurrent signal is for safety protection and needs to be restored after power off inspection. However, the overcurrent signal is a momentary state value and requires a trigger to power on again to release the overcurrent abnormal state and also ensure that an output signal is latched, such as Figure 10 As shown, when the signal of the MOS tube is high and the overcurrent signal does not exist, the MOS can be driven normally; when the signal of the MOS tube is low and the overcurrent signal does not exist, the MOS can be closed normally; when the overcurrent signal exists, the MOS tube cannot be closed regardless of whether the signal is high or low.

[0024] According to the above technical solution, it further includes the drive of the magnetic latching relay: The drive of the relay uses a drive chip to ensure the closing and opening of the magnetic latching relay by inputting the high and low levels of DOUTA and K-DOUTB. Specifically, it includes: As Figure 11 shown, at the power supply of the chip, two high-voltage MOS transistors are placed at the front end, and two magnetic latching relays are placed at the rear end. The magnetic latching relay is disconnected under the state of high voltage and large current through control logic. A resistor and a capacitor are placed between the positive and negative of the input DC to ensure the stability of the voltage at the input end of the MOS transistor without abnormal fluctuations. TVS and resistors are set at both ends of the MOS transistor to protect in case the parameters exceed the rated values of the device during the charging and disconnection instants of the MOS transistor.

[0025] According to the above technical solution, the communication unit includes: It adopts CAN communication, is isolated and communicated through an isolated CAN chip, and TVS, gas discharge tubes and self-resetting fuses are added at the output end for protection. At the same time, a common mode inductor and an RC circuit are added for anti-interference to realize the information interaction between the vehicle end and the board.

[0026] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. An optimized power-off control circuit for a relay, characterized in that: It includes a first processing module; The first processing module includes an output circuit unit, an input circuit unit, and a built-in CPU control unit; The output circuit unit is used to control the conduction and cutoff of the internal components of the output circuit, and maintain a path with the external voltage and the external indicating element; the input circuit unit externally connects a voltage through a switch. When the voltage exists, a loop is formed through a resistor and an optocoupler to ensure that the GPIO port of the microprocessor collects a high level; when the voltage does not exist, no loop can be formed, ensuring that the GPIO port of the microprocessor collects a low level through a pull-down resistor. The CPU control unit is used for communication and data acquisition to implement the charging function, and specifically includes a current sampling unit, a battery voltage unit, a pilot voltage unit, an integration unit, and a communication unit; The output circuit unit is electrically connected to the input circuit unit, and the output circuit unit and the input circuit unit are respectively electrically connected to the CPU control unit.

2. The optimized circuit for power-off control of a relay according to claim 1, wherein: The output circuit unit includes a triode output circuit unit and a relay output circuit unit; The relay output circuit unit outputs high and low levels based on the GPIO port of the microprocessor to control the conduction and cutoff of the triode. The triode is paired with the relay, and through the change of the base level, the relay is controlled, and the output end of the relay forms the functions of conduction and cutoff; the triode output circuit unit is used to form a path with the external voltage and the external indicating element to control the lighting and extinguishing of the external indicating element.

3. The optimized power-off control circuit for a relay according to claim 1, characterized in that: The current sampling unit includes: A sampling resistor is constructed, and according to Ohm's law, the current passing through the sampling resistor is converted into a voltage for current acquisition. After filtering by an inductor and a capacitor, TVS is used for protection, and an operational amplifier circuit is used for amplification processing; A follower circuit is constructed, and the voltage followed by the follower circuit is processed in two directions. One of them outputs a differential signal through an isolation operational amplifier HCPL7840, and after being processed by an operational amplifier chip, it is output to the ADC port of the microprocessor for software processing; the other operational amplifier chip processes it and outputs a voltage signal. The comparator voltage is set, and the output voltage signal is compared with the comparator voltage. If the output voltage signal is higher than the comparator voltage signal, the comparator outputs a high voltage to turn on the field effect transistor, the optocoupler operates, the optocoupler outputs a high voltage, and when the hardware receives the high voltage output by the optocoupler, it judges that overcurrent occurs and performs protection.

4. An optimized power-off control circuit for a relay according to claim 1, characterized in that: The battery voltage unit includes: During the charging process, the direct current output by the charging module is collected. The voltage is reduced to the range that can be collected by the chip using the method of resistor voltage division. TVS and an inductor are added at the input end for protection and anti-interference ability. The isolation operational amplifier HCPL7840 is used for fixed amplification to output a differential signal, and the differential signal is output to the ADC port of the microprocessor through bias voltage and operational amplifier processing; In battery voltage acquisition, by means of an unbalanced bridge, a relay is used to change the resistance between the positive and negative terminals of the battery voltage and the protective ground wire (PE terminal); the insulation resistance value between the battery voltage and the ground is calculated, and the high and low levels of the GPIO port of the microprocessor control the isolation optocoupler to disconnect and close the relay.

5. The optimized power-off control circuit for a relay according to claim 1, wherein: The guiding voltage unit includes: Judge the connection state between the voltage generated by the controller and the charging gun line, obtain the feedback of the plugging signal, output it to the ADC acquisition port of the microprocessor through resistor voltage division and the processing of the operational amplifier chip, and process the signal state through software.

6. The power-off control optimization circuit for a relay according to claim 1, characterized in that: The integration unit includes MOS transistors and magnetic latching relays; The realization of the charging pile integration K1K2 function is carried out through the GPIO port of the microprocessor. First, the 3.3V voltage is converted into a 5V level through level conversion. When the voltage of the GPIO port is high, after level conversion, it is input to the dual-channel precision monostable multivibrator and the RC delay circuit; The output of the RC delay circuit is the drive signal for the MOS transistor, and the output signal of the dual-channel precision monostable multivibrator is used to drive the magnetic latching relay to make the magnetic latching relay act. The dual-channel precision monostable multivibrator ensures the output of pulse signals DOUTA and DOUTB through the peripheral circuit and capacitor; after DOUTB passes through a delay circuit and a comparator, K-DOUTB is output. When the dual-channel precision monostable multivibrator inputs a high level, DOUTA and K-DOUTB output a pulse output logic with DOUTA high and K-DOUTB low. When the dual-channel precision monostable multivibrator inputs a low level, DOUTA and K-DOUTB output a pulse output logic level with DOUTA low and K-DOUTB high, ensuring the closing and opening of the magnetic latching relay.

7. The optimized power-off control circuit for a relay according to claim 6, wherein: It also includes: The drive signal output by the RC delay circuit to the MOS transistor passes through a fast discharge and capacitor charging delay circuit, which is staggered from the control time of the magnetic latching relay; When the GPIO port of the microprocessor inputs a high level, the magnetic latching relay closes first, and after 500ms, the MOS transistor closes; when the GPIO port of the microprocessor inputs a low level, the MOS transistor disconnects first, and the magnetic latching relay disconnects; An overcurrent signal is set to participate in controlling the disconnection of the MOS transistor. When the signal of the MOS transistor is high and the overcurrent signal does not exist, the MOS can be normally driven; when the signal of the MOS transistor is low and the overcurrent signal does not exist, the MOS can be normally turned off; when the overcurrent signal exists, regardless of whether the signal of the MOS transistor is high or low, the MOS cannot be closed.

8. The optimized power-off control circuit for a relay according to claim 7, characterized in that: It also includes the drive of the magnetic latching relay: The drive of the relay uses a drive chip to ensure the closing and opening of the magnetic latching relay by inputting the high and low levels of DOUTA and K-DOUTB. Specifically, it includes: At the power supply of the chip, two high-voltage MOS transistors are placed at the front end, and two magnetic latching relays are placed at the back end. The magnetic latching relays are disconnected under the conditions of high voltage and large current through control logic. A resistor and a capacitor are placed between the positive and negative of the input DC to ensure the stability of the voltage at the input end of the MOS transistor without abnormal fluctuations. TVS and resistors are set at both ends of the MOS transistor to provide protection when the MOS transistor is charging and disconnecting instantaneously if the parameters exceed the rated values of the device.

9. The optimized power-off control circuit for a relay according to claim 1, wherein: The communication unit includes: CAN communication is adopted. Isolation and communication are carried out through an isolated CAN chip. TVS, gas discharge tubes and self-resetting fuses are added at the output end for protection. At the same time, a common-mode inductor and an RC circuit are added for anti-interference to realize information interaction between the vehicle end and the board.

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