Short circuit detection circuit for output end of charging equipment

Abstract

The utility model discloses a charging equipment output end short circuit detection circuit, comprising a one-chip microcomputer and a relay group, an output end comprises an Lout end and a Nout end, the relay group is provided with two groups of switches, which are respectively a first switch and a second switch, one end of the first switch is connected with the Lout end, the other end is connected with a low voltage Vdc2 end, and the other end is connected with a low voltage Vdc2 end. One end of the second switch is connected with the Nout, the other end of the second switch is connected to a first pin of the single-chip microcomputer, and the voltage of the low-voltage Vdc2 end is 1-36 V. The circuit provided by the utility model can realize the short circuit detection of the output end, and improves the charging safety.

Description

Technical Field

[0001] This utility model relates to the field of new energy vehicle charging and discharging technology, specifically a short-circuit detection circuit at the output end of a charging device. Background Technology

[0002] Existing electric vehicles have AC charging, V2L (vehicle-to-load) discharge, and vehicle-to-vehicle (V2V) discharge capabilities. A charging / discharging gun is connected to the electric vehicle to enable vehicle-to-vehicle charging or vehicle-to-load discharge schemes.

[0003] Electric vehicles are charged using a charging gun or a combined charging and discharging gun. Existing charging guns are equipped with multi-functional detection circuits, but some lack output short-circuit detection circuits, posing a safety hazard. Patent CN 107688133 A discloses a power-on short-circuit detection circuit for the control box on the charging gun cable, but the circuit structure is relatively complex. Utility Model Content

[0004] The purpose of this invention is to provide a short-circuit detection circuit at the output end of a charging device. This circuit has a simple structure and can detect short circuits at the output end, thus improving charging safety. To achieve the above objective, this invention adopts the following technical solution:

[0005] This utility model discloses a short-circuit detection circuit for the output terminal of a charging device, including a microcontroller and a relay group. The output terminal includes a Lout terminal and a Nout terminal. The relay group has two sets of switches, namely a first switch and a second switch. One end of the first switch is connected to the Lout terminal and the other end is connected to the low voltage Vdc2 terminal. One end of the second switch is connected to the Nout terminal and the other end is connected to the first pin of the microcontroller. The voltage of the low voltage Vdc2 terminal is 1~36V.

[0006] Preferably, the microcontroller is further provided with a second pin, which is connected to the relay group to control the on / off state of the relay group.

[0007] The relay group can be a set of changeover relays, or two sets of changeover relays connected in series, or a set of normally open relays, or two sets of normally open relays connected in series.

[0008] In one embodiment, the relay group is a set of changeover relays K3; the changeover relay K3 has 8 pins, pin 1 is connected to the VDC terminal, and pin 8 is connected to the second pin of the microcontroller and ground. Pins 3 and 4 form a first switch, pin 3 is connected in series with a protection diode D1 to the low voltage Vdc2 terminal, and pin 4 is connected in series with a fuse FR1 to the Lout terminal. Pins 6 and 5 form a second switch, pin 6 is connected in series with a protection circuit to the first pin of the microcontroller, and pin 5 is connected to the Nout terminal. Pins 3 and 6 can be switched to be connected to pins 2 and 7, or to be switched to be connected to pins 4 and 5.

[0009] In some embodiments, the relay group consists of two sets of series-connected changeover relays K4 and K5. Both changeover relays K4 and K5 have eight pins. Pin 1 of changeover relays K4 and K5 is connected to the VDC terminal, and pin 8 is connected to the second pin of the microcontroller and ground.

[0010] For the changeover relay K4, pins 2 and 7 are normally closed contacts, pins 3 and 6 are a common terminal, and pins 4 and 5 are normally open contacts. Pin 3 is connected in series with the protection diode D2 to the Vdc2 terminal, pin 6 is connected to pin 4, and pin 5 is connected in series with the fuse FR2 to the Lout terminal. For the changeover relay K5, pins 2 and 7 are normally closed contacts, pins 3 and 6 are a common terminal, and pins 4 and 5 are normally open contacts. Pin 3 is connected to pin 5, pin 6 is connected to the protection circuit and then to the first pin of the microcontroller, and pin 4 is connected to the Nout terminal.

[0011] In some embodiments, the relay group is a set of normally open relays K6, which have 6 pins; pin 1 is connected to VDC, pin 2 is connected to the second pin of the microcontroller and ground; pin 3 is connected in series with the protection diode D3 to the low voltage Vdc2 terminal, pin 5 is connected in series with the fuse FR3 and then connected to the Lout terminal; pin 4 is connected to the protection circuit and then connected to the first pin of the microcontroller, and pin 6 is connected to the Nout terminal.

[0012] In other embodiments, the relay group consists of two normally open relays K7 and K8 connected in series; both normally open relays K7 and K8 have 6 pins; pin 1 of normally open relays K7 and K8 is connected to the VDC terminal, and pin 2 is connected to the second pin of the microcontroller and ground. Pin 3 of normally open relay K7 is connected in series with a protection diode D4 to the Vdc2 terminal, pin 4 is connected to pin 5, and pin 6 is connected to the Lout terminal. Pin 3 of normally open relay K8 is connected to pin 6, pin 4 is connected to the protection circuit and then to the first pin of the microcontroller, and pin 5 is connected to the Nout terminal.

[0013] Preferably, the protection circuit includes: transistor Q3, diode D12, resistors RP1, RP2, RP3, and RP4. The base of transistor Q3 is connected to resistor RP1, the collector is connected to resistor RP3 to VDD, and the emitter is connected to ground; diode D12 and resistor RP2 are both connected between the base and emitter of transistor Q3.

[0014] Due to the adoption of the above solution, this utility model has the following beneficial effects:

[0015] This method incorporates an output short-circuit detection circuit within the charging device (charging gun or integrated charge / discharge gun). It detects short circuits by using a low-voltage excitation method at the Vdc2 terminal. If a short circuit is detected, the microcontroller employs a protection mechanism to prevent high voltage output to the detected port, thus achieving output short-circuit detection and improving charging safety. Furthermore, this invention features a simple circuit structure, making it suitable for use in integrated charge / discharge guns with multiple circuit functions, and facilitating the layout of the integrated charge / discharge gun circuitry. Attached Figure Description

[0016] Figure 1 This is the circuit schematic diagram of this utility model.

[0017] Figure 2 This is the circuit diagram for Example 1.

[0018] Figure 3 This is the circuit diagram for Example 2.

[0019] Figure 4 This is the circuit diagram for Example 3.

[0020] Figure 5 This is the circuit diagram for Example 4. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown, this utility model discloses a short-circuit detection circuit for the output terminal of a charging device. The charging device can be a charging gun, discharging gun, integrated charging and discharging gun, or charging pile device. The output terminal includes a Lout terminal and a Nout terminal. When the charging device is connected to the vehicle, this utility model circuit can be used to detect whether there is a short circuit at the vehicle end before charging and discharging.

[0023] like Figure 1The diagram shows the schematic of a short-circuit detection circuit at the output of a charging device, which includes a microcontroller and a relay group. The microcontroller has at least a first pin, from which it obtains level information to detect whether a short circuit has occurred. Furthermore, the microcontroller also has a second pin, which is used to control the on / off state of the relay group.

[0024] The relay group has two sets of switches: a first switch and a second switch. One end of the first switch K1 is connected to the Lout terminal, and the other end is connected to the low-voltage Vdc2 terminal. One end of the second switch K2 is connected to the Nout terminal, and the other end is connected to the first pin (I / O port) of the microcontroller and ground. The voltage at the low-voltage Vdc2 terminal is 1~36V. The principle of this circuit is as follows: First, close K1 and K2. The low voltage Vdc2 flows through a resistor to the Lout terminal. If a short circuit occurs at the output terminal, the first pin of the microcontroller will detect a high level. If no short circuit occurs, the voltage of Vdc2 cannot reach the Lout terminal, and the first pin of the microcontroller will detect a low level. The high or low level detected by the first pin determines whether there is a short circuit at the output terminal.

[0025] The circuit of the short circuit detection circuit at the output terminal of the charging device can be as follows. In the following embodiment, the microcontroller is U3, which has a first pin U3-24 and a second pin U3-23.

[0026] Example 1

[0027] like Figure 2 As shown, the relay group for the short-circuit detection circuit at the output of the charging device is a changeover relay K3 with 8 pins. The changeover relay has 8 pins: pin 1 is connected to the VDC terminal, and pin 8 is connected to the second pin U3-23 of the microcontroller and ground. Pins 3 and 4 form the first switch (pin 3 is connected in series with a protection diode D1 to the low-voltage Vdc2 terminal, and pin 4 is connected in series with a fuse FR1 to the Lout terminal). The fuse FR1 automatically melts and cuts off the current when the current abnormally increases, thus protecting the circuit.

[0028] Pins 6 and 5 form a second switch (pin 6 is connected to the first pin U3-24 of the microcontroller after being connected in series with the protection circuit, and pin 5 is connected to the Nout terminal). Pins 3 and 6 can be switched to be connected to pins 2 and 7, or to be switched to be connected to pins 4 and 5.

[0029] The system uses a changeover relay, which is bipolar, allowing for seamless control of two circuits simultaneously and facilitating wiring.

[0030] To protect the microcontroller's I / O ports from high voltage damage, the other end of the second switch is connected to the protection circuit before being connected to the microcontroller. That is, pin 6 is connected to the protection circuit (the circuit enclosed in the dashed box in the diagram).

[0031] like Figure 2 The protection circuit includes: transistor Q3, diode D12, resistors RP1, RP2, RP3, and RP4. Transistor Q3 protects the microcontroller's I / O port (U3-24). The base of transistor Q3 is connected to resistor RP1, which is the base drive resistor for transistor Q3. The collector of transistor Q3 is connected to resistor RP3 to the VDD terminal; resistor RP3 is the pull-up resistor for the I / O port. The collector of transistor Q3 is also connected to resistor RP4, which is then connected to the first pin of the microcontroller, U3-24. Resistor RP4 acts as an anti-static resistor for the microcontroller's I / O port. The emitter of transistor Q3 is connected to ground. Diode D12 and resistor RP2 are both connected between the base and emitter of transistor Q3. Diode D12 is a reverse protection diode to prevent the base and emitter of transistor Q3 from breaking down during the negative half-wave. Resistor RP2 is the discharge resistor for transistor Q3 to prevent false start-up.

[0032] Example 2

[0033] like Figure 3 As shown, the relay group of the short-circuit detection circuit at the output of the charging device includes two sets of changeover relays K4 and K5, which are connected in series and each has 8 pins. Pin 1 of changeover relays K4 and K5 is connected to the VDC terminal, and pin 8 is connected to the second pin U3-23 of the microcontroller and ground. The second pin U3-23 is used to control the on / off state of changeover relays K4 and K5.

[0034] In the changeover relay K4, pins 2 and 7 are normally closed contacts, pins 3 and 6 are a common terminal, and pins 4 and 5 are normally open contacts. Pin 3 of the changeover relay K4 is connected in series with the protection diode D2 to the Vdc2 terminal, pin 6 is connected to pin 4, and pin 5 is connected in series with the fuse FR2 to the Lout terminal.

[0035] In the changeover relay K5, pins 2 and 7 are normally closed contacts, pins 3 and 6 are a common terminal, and pins 4 and 5 are normally open contacts. Pin 3 of the changeover relay K5 is connected to pin 5, pin 6 is connected to pin U3-35 of the microcontroller, and pin 4 is connected to the Nout terminal. The protection circuit in this embodiment is the same as in Embodiment 1.

[0036] Compared to Embodiment 1, this embodiment adds a conversion relay in series, which increases the voltage withstand capability.

[0037] Example 3

[0038] like Figure 4 As shown, compared to Embodiment 1, the relay group of the short circuit detection circuit at the output end of the charging device simplifies the changeover relay K3 into a normally open relay K6 with 6 pins, while the remaining wiring method is similar to Embodiment 1.

[0039] Normally open relay K6 has its pin 1 connected to VDC, pin 2 connected to the microcontroller's second pin U3-23, and then connected to ground. The second pin U3-23 controls the on / off state of K6. Pin 3 is connected in series with protection diode D3 to the low-voltage Vdc2 terminal, and pin 5 is connected in series with fuse FR3 to the Lout terminal. Pin 4 is connected in series with the protection circuit to the microcontroller's first pin U3-24, and pin 6 is connected to the Nout terminal. The protection circuit in this embodiment is the same as in embodiment one.

[0040] Compared to Embodiment 3, the circuit in Embodiment 1 features an additional winding in the changeover relay, an increased air gap, and a higher primary and secondary withstand voltage rating. However, the circuit structure in Embodiment 3 is simpler and less expensive.

[0041] Example 4

[0042] like Figure 5 As shown, compared with Embodiment 2, the relay group of the short circuit detection circuit at the output end of the charging device simplifies the conversion relays K4 and K5 into normally open relays K7 and K8 with 6 pins, and the remaining wiring methods are similar to Embodiment 2.

[0043] Normally open relay K7 has its pin 1 connected to the VDC terminal, pin 2 connected to the microcontroller's second pin U3-23 and then to ground. The second pin U3-23 is used to control the on / off state of K7 and K8. Pin 3 is connected in series with protection diode D4 to the Vdc2 terminal, pin 4 is connected to pin 5, and pin 6 is connected in series with fuse FR4 and then to the Lot terminal.

[0044] Normally open relay K8 has its pin 1 connected to the VDC terminal, pin 2 connected to the microcontroller's second pin U3-23 and then to ground. Pin 3 is connected to pin 6, pin 4 is connected to the protection circuit and then to the microcontroller's first pin U3-24, and pin 5 is connected to the Nout terminal. The high or low level detected by the first pin U3-24 allows the microcontroller to determine whether the output terminal is short-circuited. The protection circuit in this embodiment is the same as in embodiment one.

[0045] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A short-circuit detection circuit at the output terminal of a charging device, characterized in that: It includes a microcontroller and a relay group, and the output terminals include Lout and Nout terminals; The microcontroller is provided with at least a first pin, from which the microcontroller obtains level information to detect whether there is a short circuit; The relay group has two sets of switches, namely a first switch and a second switch. One end of the first switch is connected to the Lout terminal and the other end is connected to the low voltage Vdc2 terminal. One end of the second switch is connected to the Nout terminal and the other end is connected to the first pin of the microcontroller. The voltage of the low voltage Vdc2 terminal is 1~36V.

2. The short-circuit detection circuit at the output terminal of the charging device as described in claim 1, characterized in that: The microcontroller is also equipped with a second pin, which is connected to the relay group to control the on / off state of the relay group.

3. The short-circuit detection circuit at the output terminal of the charging device as described in claim 2, characterized in that: The relay group is a set of changeover relays, or two sets of changeover relays connected in series, or a set of normally open relays, or two sets of normally open relays connected in series.

4. The short-circuit detection circuit at the output terminal of the charging device as described in claim 3, characterized in that: The relay group is a set of changeover relays K3; the changeover relay K3 is provided with 8 pins, pin 1 is connected to the VDC terminal, and pin 8 is connected to the second pin of the microcontroller and ground; Pins 3 and 4 form the first switch. Pin 3 is connected in series with the protection diode D1 and then connected to the low voltage Vdc2 terminal. Pin 4 is connected in series with the fuse FR1 and then connected to the Lout terminal. Pins 6 and 5 form a second switch. Pin 6 is connected to the first pin of the microcontroller after being connected in series with the protection circuit. Pin 5 is connected to the Nout terminal. Pins 3 and 6 can be switched to connect with pins 2 and 7, or to connect with pins 4 and 5.

5. The short-circuit detection circuit at the output terminal of the charging device as described in claim 3, characterized in that: The relay group consists of two sets of series-connected changeover relays K4 and K5; Both changeover relays K4 and K5 have 8 pins. Pin 1 of changeover relays K4 and K5 is connected to the VDC terminal, and pin 8 is connected to the second pin of the microcontroller and ground. Pins 2 and 7 of the changeover relay K4 are normally closed contacts, pins 3 and 6 are common terminals, and pins 4 and 5 are normally open contacts. Pin 3 is connected in series with the protection diode D2 to the Vdc2 terminal, pin 6 is connected to pin 4, and pin 5 is connected in series with the fuse FR2 to the Lout terminal. The changeover relay K5 has normally closed contacts at pins 2 and 7, common terminals at pins 3 and 6, and normally open contacts at pins 4 and 5. Pin 3 is connected to pin 5, pin 6 is connected to the protection circuit and then to the first pin of the microcontroller, and pin 4 is connected to the Nout terminal.

6. The short-circuit detection circuit at the output terminal of the charging device as described in claim 3, characterized in that: The relay group is a set of normally open relays K6, which have 6 pins; pin 1 is connected to VDC, pin 2 is connected to the second pin of the microcontroller and ground; pin 3 is connected in series with the protection diode D3 to the low voltage Vdc2 terminal, pin 5 is connected in series with the fuse FR3 and then connected to the Lout terminal; pin 4 is connected to the protection circuit and then to the first pin of the microcontroller, and pin 6 is connected to the Nout terminal.

7. The short-circuit detection circuit at the output terminal of the charging device as described in claim 3, characterized in that: The relay group consists of two sets of normally open relays K7 and K8 connected in series; both normally open relays K7 and K8 have 6 pins; pin 1 of normally open relays K7 and K8 is connected to the VDC terminal, and pin 2 is connected to the second pin of the microcontroller and ground; Normally open relay K7 has its pin 3 connected in series with protection diode D4 and connected to Vdc2 terminal; pin 4 is connected to pin 5; and pin 6 is connected in series with fuse FR4 and then connected to Lout terminal. Normally open relay K8 has its pin 3 connected to pin 6, pin 4 connected to the protection circuit and then to the first pin of the microcontroller, and pin 5 connected to the Nout terminal.

8. The short-circuit detection circuit at the output terminal of the charging device as described in any one of claims 4 to 7, characterized in that: The protection circuit includes: transistor Q3, diode D12, resistor RP1, resistor RP2, resistor RP3 and resistor RP4; The base of transistor Q3 is connected to resistor RP1, the collector is connected to resistor RP3 to VDD, and the emitter is connected to ground; diode D12 and resistor RP2 are both connected between the base and emitter of transistor Q3; the collector of transistor Q3 is connected to resistor RP4 and then to the first pin of the microcontroller.

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