Short circuit detection method, detection circuit and charging device

Abstract

This application relates to a short-circuit detection method, detection circuit, and charging device. The detection circuit includes: an output module for providing a bidirectional current path between a first node and a second node, and providing an effective level to a signal output terminal when a current in a first direction exists in the bidirectional current path; a first trigger module and a second trigger module for, in an enabled state, starting to provide a bidirectional current path between the input and output terminals when a zero-crossing point of the voltage waveform between the input and output terminals is detected, until the current value in the bidirectional current path is lower than a current threshold; and an enable module for setting the first and second trigger modules to an enabled state when an on level is provided at a switch signal terminal. The method includes determining a short circuit when an on level is detected at the switch signal terminal and there is no effective level at the signal output terminal. This application can realize short-circuit detection of the live and neutral wires using a zero-crossing detection circuit structure.

Description

Technical Field

[0001] This application relates to the field of electronic and electrical technology, and in particular to a short-circuit detection method, detection circuit, and charging device. Background Technology

[0002] With the continuous development and application of new energy vehicle technologies, more and more electric vehicles and devices are appearing in people's daily lives, and charging equipment such as charging piles and charging stations for charging these vehicles and devices are also increasing accordingly. AC charging piles are connected to the neutral and live wires of the mains power supply via relays, so that when the relay contacts close, the charging pile can be started and begin charging the user's equipment.

[0003] Short-circuit protection is an essential function of AC power supply equipment. Before energy transfer, the AC power supply equipment should not be able to charge if a short circuit occurs in the AC output circuit. During the energy transfer phase, the AC power supply equipment should stop charging if a short circuit occurs in the AC output circuit. For the aforementioned AC charging piles, to prevent the dangerous situation where charging continues despite a short circuit between the neutral and live wires, the AC charging pile needs to be equipped with a fast-responding and reliable short-circuit detection circuit. Summary of the Invention

[0004] This application provides a short circuit detection method, detection circuit, and charging device, which can realize short circuit detection of live and neutral wires by utilizing a circuit structure that implements zero-crossing detection.

[0005] This application provides a short-circuit detection method, which is implemented using a detection circuit. The detection circuit has a switch signal terminal, a signal output terminal, a live wire connection terminal, and a neutral wire connection terminal, and includes:

[0006] An output module is connected to the signal output terminal, the first node, and the second node, respectively. The output module is configured to provide a bidirectional current path between the first node and the second node, and to provide an effective level to the signal output terminal when there is a current in a first direction in the bidirectional current path; the first direction is from the first node to the second node, or the first direction is from the second node to the first node.

[0007] A first trigger module and a second trigger module are configured such that the input terminal of the first trigger module is connected to the live wire connection terminal, and the output terminal of the first trigger module is connected to the first node; the input terminal of the second trigger module is connected to the neutral wire connection terminal, and the output terminal of the second trigger module is connected to the second node. Both the first and second trigger modules are configured to: in an enabled state, upon detecting a zero-crossing point of the voltage waveform between the input and output terminals, initiate a bidirectional current path between the input and output terminals until the current value in the bidirectional current path falls below a current threshold; and...

[0008] An enabling module is connected to the switch signal terminal, the first trigger module, and the second trigger module, respectively. The enabling module is configured to set the first trigger module and the second trigger module to the enabled state when the switch signal terminal provides an on level.

[0009] The method includes:

[0010] When the switch signal terminal is provided with the turn-on level and there is no valid level at the signal output terminal, it is determined that a short circuit has occurred between the live wire connection terminal and the neutral wire connection terminal.

[0011] In some possible implementations, determining a short circuit between the live wire connection and the neutral wire connection when the switch signal terminal is provided with the on level but the signal output terminal does not have the valid level includes:

[0012] Provide a switch control signal to the switch signal terminal and detect the voltage output by the signal output terminal;

[0013] When the switch control signal is detected to be at the on level and there is no valid level at the signal output terminal, it is determined that a short circuit has occurred between the live wire connection terminal and the neutral wire connection terminal.

[0014] This application also provides a detection circuit, which has a switch signal terminal, a signal output terminal, a live wire connection terminal, and a neutral wire connection terminal. The detection circuit includes:

[0015] An output module is connected to the signal output terminal, the first node, and the second node, respectively. The output module is configured to provide a bidirectional current path between the first node and the second node, and to provide an effective level to the signal output terminal when there is a current in a first direction in the bidirectional current path; the first direction is from the first node to the second node, or the first direction is from the second node to the first node.

[0016] A first trigger module and a second trigger module, wherein the input terminal of the first trigger module is connected to the live wire connection terminal and the output terminal of the first trigger module is connected to the first node, the input terminal of the second trigger module is connected to the neutral wire connection terminal and the output terminal of the second trigger module is connected to the second node, and both the first trigger module and the second trigger module are configured to: in the enabled state, when a zero-crossing point of the voltage waveform between the input terminal and the output terminal is detected, start providing a bidirectional current path between the input terminal and the output terminal until the current value in the bidirectional current path is lower than a current threshold;

[0017] An enabling module is connected to the switch signal terminal, the first trigger module, and the second trigger module, respectively. The enabling module is configured to set the first trigger module and the second trigger module to the enabled state when the switch signal terminal provides an on level.

[0018] In some possible implementations, each of the first trigger module and the second trigger module includes: a light-emitting unit, a zero-crossing detection unit, and a bidirectional thyristor unit; wherein, the light-emitting unit is connected to the enable module and is configured to emit light under the drive of the enable module; the zero-crossing detection unit is connected to the input and output terminals of the first trigger module or the second trigger module respectively, and is configured to provide a trigger current to the bidirectional thyristor unit when a zero-crossing point of the voltage waveform between the input and output terminals is detected; the bidirectional thyristor unit is connected to the input and output terminals of the first trigger module or the second trigger module respectively, and is configured to: when receiving the trigger current while the light-emitting unit is emitting light, provide a bidirectional current path between the input and output terminals until the current value in the bidirectional current path is lower than the current threshold.

[0019] In some possible implementations, the enabling module includes a switching element, the switching element, the light-emitting unit of the first trigger module, and the light-emitting unit of the second trigger module are connected in series between the DC power supply voltage line and the common terminal of the detection circuit, the switching control terminal of the switching element is connected to the switching signal terminal, and the switching element is configured to switch to the on state when the on level is provided at the switching signal terminal.

[0020] In some possible implementations, the enabling module includes a first transistor, a first resistor, a second resistor, and a third resistor; wherein the gate of the first transistor is connected to the switch signal terminal via the two ends of the first resistor, the first terminal of the first transistor is connected to the common terminal of the detection circuit, the second terminal of the first transistor is connected to the negative terminal of the light-emitting unit of the second trigger module, the two ends of the second resistor are respectively connected to the gate of the first transistor and the common terminal, the two ends of the third resistor are respectively connected to the positive terminal of the light-emitting unit of the first trigger module and the DC power supply voltage line, and the negative terminal of the light-emitting unit of the first trigger module is connected to the positive terminal of the light-emitting unit of the second trigger module.

[0021] In some possible implementations, the detection circuit further includes an input switch connected between the enable module and the switch signal terminal, the input switch being configured to provide the enable module with a gate-on voltage signal of the first transistor when the switch signal terminal provides the on level.

[0022] In some possible implementations, the first direction is from the second node to the first node, and the output module includes a first diode, a second diode, and a photosensitive element; wherein, the anode of the first diode is connected to the first node, and the cathode of the first diode is connected to the second node; the cathode of the second diode is connected to the first node, and the anode of the second diode is connected to the second node; the two ends of the photosensitive element are respectively connected to a DC power supply voltage line and the signal output terminal; the second diode is a light-emitting diode, and the photosensitive element is configured to switch to a conducting state when the second diode emits light.

[0023] This application also provides a charging device, the charging device including a controller, the controller including a processor and a memory, the memory storing at least one executable instruction, the processor being used to implement any of the above-described short-circuit detection methods when executing the executable instruction.

[0024] In some possible implementations, the charging device further includes at least one detection circuit of any of the above, and the controller is connected to the switch signal terminal and signal output terminal of each detection circuit respectively.

[0025] The detection circuit in this embodiment exhibits different input / output characteristics depending on whether a short circuit occurs between the live and neutral wires. When a short circuit occurs, regardless of whether the bidirectional current paths are provided, there is always no current between the first and second nodes, meaning that the output module cannot provide a valid level to the signal output terminal regardless of whether the switch signal terminal provides an on level. Conversely, when a short circuit does not occur, the signal output terminal remains in a state of no valid level when the on level is not provided (the first node is disconnected from the live wire connection, and the second node is disconnected from the neutral wire connection, therefore there is no current between the first and second nodes). When the enable level is provided, the output module periodically provides an effective level to the signal output terminal in accordance with the fluctuation of the mains voltage signal between the live wire and the neutral wire (during the positive half-cycle of the voltage waveform, there is current flowing from the first node to the second node, and during the negative half-cycle of the voltage waveform, there is current flowing from the second node to the first node; the output module provides an effective level to the signal output terminal during one of these two periods). Therefore, the signal output terminal can reflect the zero-crossing point and fluctuation period of the mains voltage signal. Furthermore, by detecting whether an effective level exists at the signal output terminal when the switch signal terminal is provided with the enable level, short-circuit detection between the live and neutral wires can be achieved. It can be seen that the circuit of this embodiment can utilize the circuit structure for zero-crossing detection to help achieve short-circuit detection between the live and neutral wires. Moreover, before the first detection of the zero-crossing point of the voltage waveform after entering the enable state, both the first and second trigger modules maintain a state where no bidirectional current path is provided between the live and neutral wires. This helps protect other circuit structures during moments prone to electrical signal surges, such as power-on startup, switch closure, and power-off reconnection, thus contributing to improved safety and reliability of related products such as charging devices.

[0026] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0028] Figure 1 This is a structural block diagram of a detection circuit provided in an embodiment of this application;

[0029] Figure 2 This is a schematic flowchart of a short-circuit detection method provided in an embodiment of this application;

[0030] Figure 3 This is a schematic diagram of the circuit structure of a detection circuit provided in an embodiment of this application;

[0031] Figure 4This is a structural block diagram of a charging device provided in an embodiment of this application. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0033] The terminology used in the embodiments section of this disclosure is for illustrative purposes only and is not intended to limit the disclosure. Unless otherwise defined, the technical or scientific terms used herein should be understood in their ordinary sense by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar words used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “a” or “one,” and similar words do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” or “containing,” and similar words mean that the elements or objects preceding “comprising,” encompass the elements or objects listed following “comprising,” and their equivalents, and do not exclude other elements or objects. The terms “connected,” “linked,” or “connected,” and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0034] Figure 1 This is a structural block diagram of a detection circuit provided in an embodiment of this application. See also... Figure 1The detection circuit has a switch signal terminal TA, a signal output terminal TB, a live wire connection terminal TL, and a neutral wire connection terminal TN, and includes an output module 11, a first trigger module 12, a second trigger module 13, and an enable module 14. The output module 11 is connected to the signal output terminal TB, a first node P1, and a second node P2, and is configured to provide a bidirectional current path between the first node P1 and the second node P2, and to provide an effective level to the signal output terminal TB when there is current flowing from the second node P2 to the first node P1 in the bidirectional current path. The input terminal of the first trigger module 12 is connected to the live wire connection terminal TL, and its output terminal is connected to the first node P1. The input terminal of the second trigger module 13 is connected to the neutral wire connection terminal TN, and its output terminal is connected to the second node P2. Both the first trigger module 12 and the second trigger module 13 are configured to, in the enabled state, start providing a bidirectional current path between the input and output terminals when a zero-crossing point of the voltage waveform between the input and output terminals is detected, until the current value in the bidirectional current path is lower than a current threshold. The enable module 14 is connected to the switch signal terminal TA, the first trigger module 12, and the second trigger module 13 respectively. The enable module 14 is configured to enable the first trigger module 12 and the second trigger module 13 when the switch signal terminal TA provides an on level.

[0035] In one example, the live wire connection terminal TL of the detection circuit is used to connect to the live wire of the mains power grid (which can be, for example, any one of the three live wires in a three-phase power grid), and the live wire connection terminal TN of the detection circuit is used to connect to the neutral wire of the mains power grid. The aforementioned switch signal terminal TA can be regarded as the signal input terminal of the detection circuit, and the aforementioned signal output terminal TB is the signal output terminal of the detection circuit. Thus, this detection circuit can achieve zero-crossing detection based on the following working principle, and can also help achieve short-circuit detection between the live and neutral wires using the circuit structure that achieves zero-crossing detection.

[0036] Scenario 1: When there is no short circuit between the live wire connection terminal TL and the neutral wire connection terminal TN, and the switch signal terminal TA does not provide an on level: Since the switch signal terminal TA does not provide an on level, the enable module 14 does not work, and thus the first trigger module 12 and the second trigger module 13 are never in the enabled state. Therefore, the first node P1 and the live wire connection terminal TL remain disconnected (the bidirectional current path is not provided), and the second node P2 and the neutral wire connection terminal TN also remain disconnected (the bidirectional current path is not provided). Therefore, even if a bidirectional current path is provided between the first node P1 and the second node P2, no current flows through them, and the output module 11 will not provide a valid level to the signal output terminal TB. Thus, the detection circuit as a whole remains in a state of no output (such as continuously outputting a low level or an invalid level).

[0037] Scenario 2: When no short circuit occurs between the live wire connection terminal TL and the neutral wire connection terminal TN, and the switch signal terminal TA provides an on-state: After the switch signal terminal TA begins to provide an on-state, the enable module 14 operates normally and sets the first trigger module 12 and the second trigger module 13 to the enabled state. At the zero-crossing point of the first voltage waveform of the mains voltage signal between the live wire connection terminal TL and the neutral wire connection terminal TN, the first trigger module 12 and the second trigger module 13 in the enabled state respectively provide a bidirectional current path between the first node P1 and the live wire connection terminal TL, and a bidirectional current path between the second node P2 and the neutral wire connection terminal TN. In addition, the output module 11 provides a bidirectional current path between the first node P1 and the second node P2. Therefore, corresponding currents will be generated in these bidirectional current paths as the voltage between the live wire connection terminal TL and the neutral wire connection terminal TN changes. Taking the zero-crossing point of the first voltage waveform at the beginning of a negative half-cycle as an example, the current flowing from the neutral wire connection terminal TN to the live wire connection terminal TL increases with the increase of the absolute value of the negative half-cycle voltage, and decreases with the decrease of the absolute value of the negative half-cycle voltage, until it drops below the current threshold (e.g., 30mA, 40mA, 50mA, 60mA, etc.). During this period, there will be current flowing from the second node P2 to the first node P1 in the output module 11. Therefore, the output module 11 will provide an effective level to the signal output terminal TB during this period, and will stop providing an effective level to the signal output terminal TB after this period ends. In this way, as the AC voltage signal of the mains voltage signal continues to fluctuate, the signal output terminal TB will output an effective level in each negative half-cycle. It should be understood that the beginning of each effective level output period corresponds to a voltage zero-crossing point where the voltage waveform changes from positive to negative, and the end of each effective level output period corresponds to a voltage zero-crossing point where the voltage waveform changes from negative to positive. Therefore, based on the electrical signal waveform of the signal output terminal TB, the zero-crossing detection result of the mains voltage signal between the live wire connection terminal TL and the neutral wire connection terminal TN can be obtained.

[0038] Scenario 3: When a short circuit occurs between the live wire connection terminal TL and the neutral wire connection terminal TN: The voltage between the live wire connection terminal TL and the neutral wire connection terminal TN is always zero. Therefore, regardless of whether the above-mentioned bidirectional current paths are provided, no current will flow between the first node P1 and the second node P2. Thus, regardless of whether the switch signal terminal TA provides an on level, in this case, the output module 11 will remain in a state of not providing an effective level to the signal output terminal TB. The detection circuit as a whole remains in a state of no output (such as continuously outputting a low level or an invalid level), and will not change with the change of input state (i.e., the output state will not change because the switch signal terminal TA provides an on level).

[0039] Comparison reveals that the aforementioned detection circuit exhibits different input-output characteristics depending on whether a short circuit occurs between the live and neutral wires. When a short circuit occurs, the output terminal TB maintains no valid output level regardless of changes in the input signal at the switch signal terminal TA. When a short circuit does not occur, the output terminal TB periodically outputs a valid level during the period when the switch signal terminal TA provides an on level. The signal output by the output terminal TB reflects the zero-crossing point and fluctuation period of the mains voltage signal, thus achieving zero-crossing detection. Furthermore, by comparing the signal logic relationship between the switch signal terminal TA and the output terminal TB, it is possible to determine whether a short circuit has occurred between the live and neutral wires. In one example, short circuit detection between the live and neutral wires can be achieved by detecting whether a valid level exists at the output terminal TB when the switch signal terminal TA is provided with an on level.

[0040] Figure 2 This is a schematic flowchart illustrating the steps of a short-circuit detection method provided in an embodiment of this application. See also... Figure 2 This short-circuit detection method utilizes Figure 1 The detection circuit shown is implemented and includes the following steps.

[0041] In step 201, a switch control signal is provided to the switch signal terminal, and the voltage output by the signal output terminal is detected.

[0042] In step 202, when the switch control signal is detected to be at the on level and there is no valid level at the signal output terminal, it is determined that a short circuit has occurred between the live wire connection terminal and the neutral wire connection terminal.

[0043] In one example, the above short-circuit detection method is executed by a controller connected to the switch signal terminal TA and the signal output terminal TB respectively: In step 201 above, the controller outputs a switch control signal that switches between high level (on level) and low level (off level) at the input / output port connected to the switch signal terminal TA, and performs voltage sampling measurement at the input / output port connected to the signal output terminal TB to detect the voltage output by the signal output terminal TB, and generates a zero-crossing detection signal from the change in its voltage value (as mentioned above, under normal operating conditions, this signal corresponds to the negative half-cycle of the mains voltage signal). (The signal is active at a high level during each time period and remains inactive at other time periods); In step 202 above, the controller compares the switch control signal with the zero-crossing detection signal in each detection cycle to determine whether there is a situation in the current detection cycle where the switch control signal is high (on level) for a sufficiently long period of time but the zero-crossing detection signal remains inactive. If so, it is determined that a short circuit has occurred between the live wire connection terminal and the neutral wire connection terminal, and the corresponding short circuit protection operation is performed (such as disconnecting the electronic device from the mains power grid, disconnecting the electronic device from other devices, etc.).

[0044] As can be seen, the circuit of this application embodiment can help realize the short circuit detection of the live and neutral wires by utilizing the circuit structure that realizes zero-crossing detection. Moreover, the first trigger module 12 and the second trigger module 13 maintain a state of not providing a bidirectional current path between the neutral and live wires before the voltage waveform is detected to zero-cross for the first time after entering the enabled state. This can help protect other circuit structures (prevent the electrical signals on the live or neutral wires from impacting the internal circuit structure) at moments when electrical signal impact is likely to occur, such as power-on, switch closure, and power failure reconnection. This helps to improve the safety and reliability of related products such as charging equipment.

[0045] It should be noted that although the above description uses "output module 11 provides an effective level to signal output terminal TB when there is current flowing from the second node P2 to the first node P1 in the bidirectional current path" as an example, in other implementations, output module 11 can be configured to provide an effective level to signal output terminal TB when there is current flowing from the first node P1 to the second node P2 in the bidirectional current path. Thus, in the above scenario two, signal output terminal TB will output an effective level in each positive half-cycle. At this time, the beginning of each effective level output period will correspond to a voltage zero-crossing point where the voltage waveform changes from negative to positive, and the end of each effective level output period will correspond to a voltage zero-crossing point where the voltage waveform changes from positive to negative. The working principle of other parts of the circuit remains unchanged.

[0046] It should also be noted that the switching control signal of the switch signal terminal TA in the above text is provided by the controller (example of the execution subject of the short circuit detection method), but it may not be limited to this in other examples; for example, the switch signal terminal TA may be controlled by a mechanical switch and / or other control devices alone or together, and the controller (example of the execution subject of the short circuit detection method) can realize the above short circuit detection process by acquiring the switching control signal of the switch signal terminal TA.

[0047] It should also be noted that in any of the above short-circuit detection methods, "the switch signal terminal TA is provided with an on level and there is no effective level at the signal output terminal TB" may not be the only factor for the controller to determine whether a short circuit has occurred. The controller may add other judgment conditions such as "the power grid plug-in port of the electronic device is in a plugged-in state" to the short-circuit protection trigger conditions (as a prerequisite for subsequent judgment, a condition that needs to be met together, or a condition that only one needs to be met, etc.) to implement different forms of short-circuit protection according to the actual application scenario. The embodiments of this application do not limit this.

[0048] Figure 3 This is a schematic diagram of the circuit structure of a detection circuit provided in an embodiment of this application.

[0049] See Figure 3 , Figure 3 The first trigger module 12 and the second trigger module 13 have the same internal circuit structure, and each includes a light-emitting unit LD, a zero-crossing detection unit ZC, and a bidirectional thyristor unit SR. The light-emitting unit LD is connected to the enable module 14 and is configured to emit light under the drive of the enable module 14. The zero-crossing detection unit ZC is connected to the input and output terminals of either the first trigger module 12 or the second trigger module 13, and is configured to provide a trigger current to the bidirectional thyristor unit SR when a zero-crossing point of the voltage waveform between the input and output terminals is detected. The bidirectional thyristor unit SR is connected to the input and output terminals of either the first trigger module 12 or the second trigger module 13, and is configured to provide a bidirectional current path between the input and output terminals when a trigger current is received while the light-emitting unit LD is emitting light, until the current value in the bidirectional current path is lower than a current threshold.

[0050] In some examples, the first trigger module 12 and / or the second trigger module 13 are implemented using a thyristor output optocoupler chip. In this case, the light-emitting unit LD is implemented using an infrared light-emitting diode, the zero-crossing detection unit ZC is implemented using any circuit structure with the aforementioned zero-crossing detection function, and the bidirectional thyristor unit SR is implemented using... Figure 3 The three-terminal bidirectional thyristor switching element shown is used to achieve this. Because thyristor output optocouplers have good isolation performance, small size, and strong anti-interference capabilities, they help improve the safety and reliability of the detection circuits and related products implemented as a result.

[0051] See Figure 3 , Figure 3The enable module 14 includes a first transistor Q1, a first resistor R1, a second resistor R2, and a third resistor R3. In this circuit, the gate of the first transistor Q1 is connected to the input switch KA (i.e., the switch signal terminal TA, which can be a relay or other type of controllable switching element controlled by the switch control signal at the switch signal terminal TA) through the two ends of the first resistor R1. The first terminal (taking the source as an example) of the first transistor Q1 is connected to the common terminal GND of the detection circuit. The second terminal (taking the drain as an example) of the first transistor Q1 is connected to the negative terminal of the light-emitting unit LD of the second trigger module 13. The two ends of the second resistor R2 are respectively connected to the gate of the first transistor Q1 and the common terminal GND. The two ends of the third resistor R3 are respectively connected to the positive terminal of the light-emitting unit LD of the first trigger module 12 and the DC power supply voltage line VC (which provides a fixed DC voltage value, such as 15V, 12V, 10V, 5.5V, 5V, 3.3V, 3V, 1.5V, etc.). The negative terminal of the light-emitting unit LD of the first trigger module 12 is connected to the positive terminal of the light-emitting unit LD of the second trigger module 13. Thus, the light-emitting unit LD of the first trigger module 12, the light-emitting unit LD of the second trigger module 13, and the first transistor Q1 are connected in series between the DC power supply voltage line VC and the common terminal GND. The above circuit structure forms a switching control circuit (or driving circuit) for the two light-emitting units LD. When the first transistor Q1 is working in the cutoff region (i.e., the switch is off), no current flows through the two light-emitting units LD, so that the first trigger module 12 and the second trigger module 13 are in an unenabled state. When the first transistor Q1 is working in the linear region or the saturation region (i.e., the switch is on), current flows through the two light-emitting units LD, causing them to emit light, so that the first trigger module 12 and the second trigger module 13 are in an enabled state (i.e., the bidirectional thyristor unit SR is in a state where it can be illuminated by the light emitted by the light-emitting unit LD). Here, the first resistor R1 protects the first transistor Q1 and provides an appropriate gate bias voltage, and the second resistor R2 stabilizes the gate voltage of the first transistor Q1 (when the input switch KA is off or the switch signal terminal TA is floating, the second resistor R2 pulls the gate voltage of the first transistor Q1 down to zero potential). The third resistor R3 serves to protect the two light-emitting units LD and the first transistor Q1 from high current surges.

[0052] by Figure 3Taking the circuit structure shown as an example, in some possible implementations, the enable module 14 includes a switching element. This switching element, the light-emitting unit LD of the first trigger module 12, and the light-emitting unit LD of the second trigger module 13 are connected in series between the DC power supply voltage line VC and the common terminal GND of the detection circuit. The switching control terminal of the switching element is connected to the switching signal terminal TA and is configured to switch to the on state when the switching signal terminal TA provides an on level. For example, a device other than a metal-oxide-semiconductor field-effect transistor (MOSFET) can be used as the switching element (instead of the first transistor Q1), such as other types of transistors, controllable resistors, controllable diodes, or any other circuit structure with equivalent switching function. Moreover, in other examples, the positions of the switching element, the light-emitting unit LD of the first trigger module 12, and the light-emitting unit LD of the second trigger module 13 in the series path can be interchanged. In addition, in some possible implementations, the enable module 14 may also include two switching elements to control whether to provide light-emitting current to the light-emitting unit LD of the first trigger module 12 and whether to provide light-emitting current to the light-emitting unit LD of the second trigger module 13, respectively.

[0053] exist Figure 3 The detection circuit also includes an input switch K2, which is connected between the enable module 14 and the switch signal terminal TA. K2 is configured to provide the enable module 14 with a gate-on voltage signal for the first transistor Q1 when the switch signal terminal TA provides an on level (i.e., to ensure that the first transistor Q1 operates in the linear or saturation region). Thus, the input switch K2 can perform DC-DC conversion between the switch signal terminal TA and the aforementioned switching element to provide a suitable on-state voltage value to the control terminal of the switching element in the enable module 14. Alternatively, the input switch K2 can be omitted, in which case the switch signal terminal TA is directly connected to the enable module 14.

[0054] See Figure 3 , Figure 3The output module 11 includes a first diode D1, a second diode D2, and a photosensitive element Q2. The anode of the first diode D1 is connected to the first node P1, and the cathode of the first diode D1 is connected to the second node P2. The cathode of the second diode D2 is connected to the first node P1, and the anode of the second diode D2 is connected to the second node P2. The two ends of the photosensitive element Q2 are connected to the DC power supply voltage line VC and the signal output terminal TB, respectively. The second diode D2 is a light-emitting diode, and the photosensitive element Q2 is configured to switch to a conducting state when the second diode D2 emits light. Furthermore, the detection circuit includes a fourth resistor R4, the two ends of which are connected to the signal output terminal TB and the common terminal GND of the detection circuit, respectively. Thus, the first diode D1 and the second diode D2 can provide a bidirectional current path between the first node P1 and the second node P2. When there is current flowing from the second node P2 to the first node P1 in this bidirectional current path, the second diode D2 emits light, causing the photosensitive element Q2 to switch to a conducting state, so that the signal output terminal TB is provided with an effective level (high level) from the DC power supply voltage line VC. The fourth resistor R4 here can stabilize the voltage at the signal output terminal TB and protect the signal output terminal TB from current surges.

[0055] See Figure 3 In addition to the circuit structure described above, a fifth resistor R5 is connected between the output terminal of the first trigger module 12 and the first node P1, and a sixth resistor R6 is connected between the output terminal of the second trigger module 13 and the second node P2. This provides sufficiently large resistance between the live wire and the neutral wire to limit the maximum current value of each bidirectional current path and protect the devices in the current path. In one example, the resistance value of the fifth resistor R5 is twice the resistance value of the sixth resistor R6; for example, the resistance value of the fifth resistor R5 is 200k ohms and the resistance value of the sixth resistor R6 is 100k ohms, thus giving the live wire side a stronger resistance to current surges.

[0056] Figure 4 This is a structural block diagram of a charging device provided in an embodiment of this application. See also... Figure 4 The charging device includes at least one detection circuit 100. Figure 4 Taking one as an example, it may have the structure of any of the above-described detection circuits and a controller 200 connected to the detection circuit 100. In one example, the controller 200 is connected to the switch signal terminal and the signal output terminal of the detection circuit 100, respectively, and the controller 200 can be implemented with reference to any of the above-described short-circuit detection method examples.

[0057] It should be noted that the charging device in this application embodiment may be a device including at least one of the following structures: charging pile, charging box, charging station, charging system, charging circuit assembly, etc., and this application embodiment does not limit this. In one example, the charging device includes a charging pile and at least one charging gun (e.g., one, two, three, four, five, six or more), each charging gun is connected to the charging pile, and each charging gun is equipped with one, two, three or more switching elements (e.g., relays), and the control terminal of each switching element is directly or indirectly connected to the controller 200. In addition, the controller 200 may be disposed inside the charging pile as a component of the charging pile. In one example, the controller 200 may include one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors or other electronic components.

[0058] It can be seen that the detection circuit in the charging device of this application embodiment can help realize the short circuit detection of the neutral and live wires by utilizing the circuit structure that realizes zero-crossing detection. Moreover, the first and second trigger modules maintain a state of not providing a bidirectional current path between the neutral and live wires before the voltage waveform first crosses the zero point after entering the enabled state. This can help protect other circuit structures at moments when electrical signal impacts are likely to occur, such as power-on, switch closure, and power failure reconnection, thereby helping to improve the safety and reliability of related products such as charging devices.

[0059] The above description is merely an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A short-circuit detection method, characterized in that, The method is implemented using a detection circuit, which has a switch signal terminal, a signal output terminal, a live wire connection terminal, and a neutral wire connection terminal, and includes: An output module is connected to the signal output terminal, the first node, and the second node, respectively. The output module is configured to provide a bidirectional current path between the first node and the second node, and to provide an effective level to the signal output terminal when there is a current in a first direction in the bidirectional current path; the first direction is from the first node to the second node, or the first direction is from the second node to the first node. A first trigger module and a second trigger module, wherein the input terminal of the first trigger module is connected to the live wire connection terminal, and the output terminal of the first trigger module is connected to the first node; the input terminal of the second trigger module is connected to the neutral wire connection terminal, and the output terminal of the second trigger module is connected to the second node; the first trigger module and the second trigger module are each configured to: in an enabled state, upon detecting a zero-crossing point of the voltage waveform between the input terminal and the output terminal, initiate a bidirectional current path between the input terminal and the output terminal until the current value in the bidirectional current path is lower than a current threshold; and... An enabling module is connected to the switch signal terminal, the first trigger module, and the second trigger module, respectively. The enabling module is configured to set the first trigger module and the second trigger module to the enabled state when the switch signal terminal provides an on level. The method includes: When the switch signal terminal is provided with the turn-on level and there is no valid level at the signal output terminal, it is determined that a short circuit has occurred between the live wire connection terminal and the neutral wire connection terminal.

2. The method according to claim 1, characterized in that, The step of determining a short circuit between the live wire connection terminal and the neutral wire connection terminal when the switch signal terminal is provided with the on level but the signal output terminal does not have the valid level includes: Provide a switch control signal to the switch signal terminal and detect the voltage output by the signal output terminal; When the switch control signal is detected to be at the on level and there is no valid level at the signal output terminal, it is determined that a short circuit has occurred between the live wire connection terminal and the neutral wire connection terminal.

3. A detection circuit for short circuit detection, characterized in that, The detection circuit has a switch signal terminal, a signal output terminal, a live wire connection terminal, and a neutral wire connection terminal, and includes: An output module is connected to the signal output terminal, the first node, and the second node, respectively. The output module is configured to provide a bidirectional current path between the first node and the second node, and to provide an effective level to the signal output terminal when there is a current in a first direction in the bidirectional current path; the first direction is from the first node to the second node, or the first direction is from the second node to the first node. A first trigger module and a second trigger module, wherein the input terminal of the first trigger module is connected to the live wire connection terminal, and the output terminal of the first trigger module is connected to the first node; the input terminal of the second trigger module is connected to the neutral wire connection terminal, and the output terminal of the second trigger module is connected to the second node; the first trigger module and the second trigger module are each configured to: in an enabled state, upon detecting a zero-crossing point of the voltage waveform between the input terminal and the output terminal, initiate a bidirectional current path between the input terminal and the output terminal until the current value in the bidirectional current path is lower than a current threshold; and... An enabling module is connected to the switch signal terminal, the first trigger module, and the second trigger module, respectively. The enabling module is configured to set the first trigger module and the second trigger module to the enabled state when the switch signal terminal provides an on level.

4. The detection circuit according to claim 3, characterized in that, Each of the first trigger module and the second trigger module includes: a light-emitting unit, a zero-crossing detection unit, and a bidirectional thyristor unit; wherein, the light-emitting unit is connected to the enable module and is configured to emit light under the drive of the enable module; the zero-crossing detection unit is connected to the input and output terminals of the first trigger module or the second trigger module respectively, and is configured to provide a trigger current to the bidirectional thyristor unit when a zero-crossing point of the voltage waveform between the input and output terminals is detected; the bidirectional thyristor unit is connected to the input and output terminals of the first trigger module or the second trigger module respectively, and is configured to: when receiving the trigger current while the light-emitting unit is emitting light, provide a bidirectional current path between the input and output terminals until the current value in the bidirectional current path is lower than the current threshold.

5. The detection circuit according to claim 4, characterized in that, The enabling module includes a switching element. The switching element, the light-emitting unit of the first trigger module, and the light-emitting unit of the second trigger module are connected in series between the DC power supply voltage line and the common terminal of the detection circuit. The switching control terminal of the switching element is connected to the switching signal terminal. The switching element is configured to switch to the on state when the on level is provided at the switching signal terminal.

6. The detection circuit according to claim 4, characterized in that, The enabling module includes a first transistor, a first resistor, a second resistor, and a third resistor; wherein, The gate of the first transistor is connected to the switch signal terminal through the two ends of the first resistor. The first terminal of the first transistor is connected to the common terminal of the detection circuit. The second terminal of the first transistor is connected to the negative terminal of the light-emitting unit of the second trigger module. The two ends of the second resistor are respectively connected to the gate of the first transistor and the common terminal. The two ends of the third resistor are respectively connected to the positive terminal of the light-emitting unit of the first trigger module and the DC power supply voltage line. The negative terminal of the light-emitting unit of the first trigger module is connected to the positive terminal of the light-emitting unit of the second trigger module.

7. The detection circuit according to claim 6, characterized in that, The detection circuit further includes an input switch connected between the enable module and the switch signal terminal. The input switch is configured to provide the enable module with a gate-on voltage signal of the first transistor when the switch signal terminal provides the on level.

8. The detection circuit according to any one of claims 3 to 7, characterized in that, The first direction is from the second node to the first node, and the output module includes a first diode, a second diode, and a photosensitive element; wherein, The anode of the first diode is connected to the first node, and the cathode of the first diode is connected to the second node; the cathode of the second diode is connected to the first node, and the anode of the second diode is connected to the second node; the two ends of the photosensitive element are respectively connected to the DC power supply voltage line and the signal output terminal; the second diode is a light-emitting diode, and the photosensitive element is configured to switch to the on state when the second diode emits light.

9. A charging device, characterized in that, The charging device includes a controller, which includes a processor and a memory. The memory stores at least one executable instruction, and the processor is used to implement the method as described in claim 1 or 2 when executing the executable instruction.

10. The charging device according to claim 9, characterized in that, The charging device further includes at least one detection circuit as described in any one of claims 3 to 8, wherein the controller is connected to the switch signal terminal and the signal output terminal of each of the detection circuits respectively.

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