Short circuit detection circuit before closing of charging pile relay

Abstract

A short circuit detection circuit before closing of a charging pile relay relates to the field of electric vehicle charging piles, driving voltage drives a light emitting diode of an isolation optocoupler to be lightened, so that a detection signal of an MCU of a charging pile is changed from a high level to a low level, and the MCU of the charging pile forbids the relay to be closed according to a low level signal of short circuit detection. And equipment tripping or equipment damage is avoided. When the load end of the relay is connected with the charger and the battery of the electric vehicle, the resistance of the load end is increased, so that the voltage of the input side of the isolation optocoupler 6 is reduced, the light emitting diode in the driver cannot be lightened, and the detection signal of the MCU is always kept at a high level. Before the relay of the charging pile is closed, whether the output end of the relay is short-circuited can be detected, so that short-circuit faults are avoided, the maintenance cost is reduced, the service life of equipment is prolonged, and major fire disasters are avoided.

Description

Technical Field

[0001] The invention relates to the field of electric vehicle charging piles, and in particular to a short-circuit detection circuit before a charging pile relay is closed. Background Art

[0002] Existing two-wheeled / three-wheeled electric vehicle charging piles generally do not have a short-circuit detection function before the relay is closed. When the charging pile performs charging-related operations and closes the relay, if a short circuit occurs on the charging line, it will cause the equipment to trip for protection. In more serious cases, it will burn out the charging pile circuit board and cause a fire. Summary of the invention

[0003] In order to overcome the deficiencies of the above technologies, the present invention provides a short-circuit detection circuit before the charging pile relay is closed, which protects the charging pile from damage.

[0004] The technical solution adopted by the present invention to overcome the technical problems is: A short-circuit detection circuit before the charging pile relay is closed, comprising: The relay has its coil port 1 connected to a 12V power supply, its common port 5 connected to the neutral line via the load, and its load port 2 connected to the live line; A transistor, whose collector is connected to port 4 of the coil of the relay, whose emitter is grounded, and whose base is connected to the control signal output terminal of the MCU of the charging pile; The cathode of the input end of the isolation optocoupler is connected to the No. 3 port of the relay load and one end of the resistor V via resistor VI, and the anode of the input end is connected to the other end of the resistor V and one end of the resistor III, and the other end of the resistor III is connected to the live wire via resistor IV. The emitter of the output end of the isolation optocoupler is grounded, and the collector of the output end of the isolation optocoupler is connected to the power supply VCC and the detection signal input end of the MCU of the charging pile.

[0005] Furthermore, the above relay is a single-pole double-throw relay.

[0006] Furthermore, the above-mentioned transistor is an NPN transistor.

[0007] Furthermore, it also includes a diode I, whose anode is respectively connected to the No. 4 port of the coil of the relay and the collector of the transistor, and whose cathode is connected to the No. 1 port of the coil of the relay.

[0008] Furthermore, it also includes resistor I and resistor II, one end of resistor I and resistor II are respectively connected to the base of the transistor, the other end of resistor I is grounded, and the other end of resistor II is connected to the control signal output end of the MCU of the charging pile.

[0009] Further, the resistance value of resistor VI is 51 KΩ, the resistance value of resistor V is 5.1 KΩ, the resistance value of resistor III is 150 KΩ, and the resistance value of resistor IV is 200 KΩ.

[0010] Furthermore, it also includes a diode III, whose anode is connected to the cathode of the input end of the isolation optocoupler via a resistor VI, and whose cathode is connected to port No. 3 of the load of the relay.

[0011] Furthermore, it also includes a diode II, whose anode is connected to the live wire via a resistor VI, and whose cathode is connected to the resistor IV.

[0012] Furthermore, it also includes a resistor VII, and the output collector of the isolation optocoupler is connected to the power supply VCC via the resistor VII.

[0013] The beneficial effects of the present invention are as follows: the driving voltage drives the light-emitting diode of the isolation optocoupler to light up, so that the detection signal of the MCU of the charging pile changes from a high level to a low level. The MCU of the charging pile prohibits the relay from closing according to the low-level signal of the short-circuit detection, thereby avoiding the tripping of the equipment or damage to the equipment. When the load end of the relay is connected to the charger and the electric vehicle battery, the resistance of the load end increases, which reduces the voltage on the input side of the isolation optocoupler 6 and cannot drive the internal light-emitting diode to light up, thereby keeping the detection signal of the MCU at a high level. Before the charging pile relay is closed, it is possible to detect whether the relay output end is short-circuited, thereby avoiding the occurrence of short-circuit faults, reducing maintenance costs, extending the service life of the equipment, and avoiding the occurrence of major fires. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The circuit diagram of the present invention is In the figure, 1. single-pole double-throw relay 2. transistor 3. diode I 4. resistor I 5. resistor II 6. isolation optocoupler 7. diode II 8. resistor III 9. resistor IV 10. resistor V 11. resistor VI 12. diode III 13. resistor VII. DETAILED DESCRIPTION

[0015] The following is combined with Figure 1 The present invention is further described.

[0016] A short-circuit detection circuit before a charging pile relay is closed, comprising: a relay, wherein port No. 1 of a coil is connected to a 12V power supply, port No. 5 of a common end is connected to a neutral line via a load, and port No. 2 of a load is connected to a live line; a transistor 2, wherein a collector is connected to port No. 4 of a coil of the relay, an emitter is grounded, and a base is connected to a control signal output end of an MCU of the charging pile; an isolation optical coupler 6, wherein a cathode of an input end is respectively connected to port No. 3 of the load of the relay and one end of a resistor V10 via a resistor VI11, an anode of an input end is respectively connected to the other end of the resistor V10 and one end of a resistor III8, the other end of the resistor III8 is connected to the live line via a resistor IV9, an emitter of an output end of the isolation optical coupler 6 is grounded, and an output collector of the isolation optical coupler 6 is respectively connected to a power supply VCC and a detection signal input end of the MCU of the charging pile. When the MCU of the charging pile is closed, the No. 2 port of its load is connected to the No. 5 port of its common end, and the AC power is transmitted to the load. When the load is short-circuited, the current on the live line flows to the neutral line after passing through the circuit composed of resistor IV 9, resistor III 8, resistor V 10, resistor VI 11, the No. 3 port of the load of the relay, and the No. 5 port of the common end of the relay 5, generating a driving voltage. The driving voltage drives the light-emitting diode of the isolation optocoupler 6 to light up, so that the detection signal of the MCU of the charging pile changes from a high level to a low level. The MCU of the charging pile prohibits the relay from closing according to the low-level signal of the short-circuit detection, thereby avoiding the tripping of the equipment or damage to the equipment. When the load end of the relay is connected to the charger and the electric vehicle battery, the voltage on the input side of the isolation optocoupler 6 is reduced due to the increase in resistance at the load end, and the internal light-emitting diode of the driver cannot be lit, so that the detection signal of the MCU always remains at a high level. Before the relay is closed, the short-circuit detection circuit can quickly determine whether the relay output is short-circuited. If a short circuit occurs, the charging pile will prohibit the closing of the relay, thereby protecting the equipment from damage.

[0017] In one embodiment of the present invention, the relay is a single-pole double-throw relay 1, and the transistor 2 is an NPN transistor.

[0018] In one embodiment of the present invention, a diode I 3 is further included, whose anode is respectively connected to the No. 4 terminal of the coil of the relay and the collector of the transistor 2, and whose cathode is connected to the No. 1 terminal of the coil of the relay. The diode I 3 plays a protective role.

[0019] In one embodiment of the present invention, a resistor I 4 and a resistor II 5 are also included, one end of the resistor I 4 and the resistor II 5 are respectively connected to the base of the transistor 2, the other end of the resistor I 4 is grounded, and the other end of the resistor II 5 is connected to the control signal output end of the MCU of the charging pile. The resistor I 4 and the resistor II 5 are both current limiting resistors.

[0020] In one embodiment of the present invention, the resistance of resistor VI 11 is 51KΩ, the resistance of resistor V 10 is 5.1KΩ, the resistance of resistor III 8 is 150KΩ, and the resistance of resistor IV 9 is 200KΩ. A diode III 12 may also be included, whose positive electrode is connected to the cathode of the input end of the isolation optical coupler 6 via resistor VI 11, and whose negative electrode is connected to port 3 of the load of the relay. A diode II 7 may also be included, whose positive electrode is connected to the live wire via resistor VI 11, and whose negative electrode is connected to resistor IV 9. Diode III 12 and diode II 7 are rectifier diodes, which can convert alternating alternating current with alternating directions into pulsed direct current with a single direction, thereby completing the function of rectification. If a short circuit occurs at the load end, the current on the live wire will flow to the neutral line through diode II 7, resistor IV 9, resistor III 8, resistor V 10, resistor VI 11, diode III 12, port No. 3 of the load of the relay, and port No. 5 of the common end of relay 5, thus forming a closed circuit. After calculation, the voltage on the input side of the isolation optocoupler 6 is (220V*5.1KΩ) / (200KΩ+150KΩ+5.1KΩ+51KΩ)≈2.76V.

[0021] In one embodiment of the present invention, a resistor VII 13 is further included, and the collector of the output end of the isolation optical coupler 6 is connected to the power supply VCC via the resistor VII 13. The resistor VII 13 is a current limiting resistor.

[0022] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A short-circuit detection circuit before the charging pile relay is closed, characterized in that: include: The relay has its coil port 1 connected to a 12V power supply, its common port 5 connected to the neutral line via the load, and its load port 2 connected to the live line; A transistor (2), whose collector is connected to port 4 of the coil of the relay, whose emitter is grounded, and whose base is connected to the control signal output terminal of the MCU of the charging pile; The isolation optocoupler (6) has an input end cathode connected to the No. 3 port of the relay load and one end of the resistor V (10) via a resistor VI (11), an input end anode connected to the other end of the resistor V (10) and one end of the resistor III (8), the other end of the resistor III (8) connected to the live wire via a resistor IV (9), an output end emitter of the isolation optocoupler (6) grounded, and an output end collector of the isolation optocoupler (6) connected to a power supply VCC and a detection signal input end of the MCU of the charging pile.

2. The short-circuit detection circuit before the charging pile relay is closed according to claim 1, characterized in that: The relay is a single-pole double-throw relay (1).

3. The short-circuit detection circuit before the charging pile relay is closed according to claim 1, characterized in that: The transistor (2) is an NPN transistor.

4. The short-circuit detection circuit before the charging pile relay is closed according to claim 1, characterized in that: It also includes a diode I (3), whose anode is connected to the No. 4 terminal of the coil of the relay and the collector of the transistor (2), and whose cathode is connected to the No. 1 terminal of the coil of the relay.

5. The short-circuit detection circuit before the charging pile relay is closed according to claim 1, characterized in that: It also includes a resistor I (4) and a resistor II (5), one end of the resistor I (4) and the resistor II (5) are respectively connected to the base of the transistor (2), the other end of the resistor I (4) is grounded, and the other end of the resistor II (5) is connected to the control signal output end of the MCU of the charging pile.

6. The short-circuit detection circuit before the charging pile relay is closed according to claim 1, characterized in that: The resistance value of resistor VI (11) is 51 KΩ, the resistance value of resistor V (10) is 5.1 KΩ, the resistance value of resistor III (8) is 150 KΩ, and the resistance value of resistor IV (9) is 200 KΩ.

7. The short-circuit detection circuit before the charging pile relay is closed according to claim 1, characterized in that: It also includes a diode III (12), whose anode is connected to the cathode of the input end of the isolation optical coupler (6) via a resistor VI (11), and whose cathode is connected to port No. 3 of the load of the relay.

8. The short-circuit detection circuit before the charging pile relay is closed according to claim 1, characterized in that: It also includes a diode II (7), the positive electrode of which is connected to the live wire via a resistor VI (11), and the negative electrode of which is connected to a resistor IV (9).

9. The short-circuit detection circuit before the charging pile relay is closed according to claim 1, characterized in that: It also includes a resistor VII (13), and the output collector of the isolation optical coupler (6) is connected to the power supply VCC via the resistor VII (13).

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