Non-isolated plug short circuit detection circuit

Abstract

The utility model provides a non-isolated plug short circuit detection circuit comprising a first relay whose control side is coupled with a controller through a first control circuit, a normally open end of a switch side is coupled with a power supply live wire, a common end is coupled with a live wire terminal of a charging plug, and a normally closed end is coupled with a first end of a switch side of a second relay; the control side of the second relay is coupled with the controller through a second control circuit, and the second end of the switch side of the second relay is coupled with the partial pressure detection circuit; the voltage division detection circuit comprises a star-shaped circuit formed by at least three resistors, and the star-shaped circuit is respectively coupled with the second end of the switch side of the second relay, reference voltage and the controller; and the controller is used for controlling the on or off of the first relay and the second relay through the control circuit, receiving the output voltage of the partial voltage detection circuit when the second relay is started, and judging whether the charging plug is short-circuited or not. According to the scheme of the utility model, reliable short-circuit detection can be realized while the cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to circuit detection technical field, concretely relates to a non -isolated plug short circuit detection circuit. BACKGROUND

[0002] The safe charging pile should satisfy before providing power supply for terminal equipment, effectively monitor the output state of itself, ensure that power supply can normally output, wherein including detecting whether the output port of the charging pile is short -circuited before charging.

[0003] Generally, the output port of the charging pile for charging two -wheeled battery car is single -phase alternating -current high voltage, and the working voltage of the singlechip in the detection control system is direct -current low voltage, which leads to the singlechip being unable to judge whether the plug -in port output is short -circuited by directly measuring the output port voltage state. Meanwhile, based on the safety requirement, the detection of alternating -current high voltage and direct -current low voltage should be properly isolated to prevent the damage of equipment caused by the flow of high voltage through the chip.

[0004] The existing isolation scheme is mostly the optical coupling isolation scheme, the principle is to connect the zero line with the isolated ground, when the output is short -circuited, the optical coupling is turned on, and the singlechip receives the feedback signal, when the output is not connected, the optical coupling is cut off, and the feedback signal remains unchanged, so as to judge whether the output end is short -circuited. But this design scheme has two obvious shortcomings: 1) the whole circuit part needs to be isolated as a whole, and the cost rises, 2) the design schemes of various battery car chargers are different, if the input end equivalent resistance of the charger is small, it is possible to misjudge the output short -circuited, thereby leading to the equipment being unable to start, and the compatibility is poor. SUMMARY

[0005] Based on the above background, the utility model provides a non -isolated plug short circuit detection circuit, which can guarantee that the feedback signal changes only when the output end is completely short -circuited while reducing the cost of the scheme. Specifically, the following technical scheme is adopted:

[0006] A non -isolated plug short circuit detection circuit, comprising:

[0007] The first relay, the control side is coupled to the controller through the first control circuit, the normally open end of the switch side is coupled to the power supply live wire, the common end is coupled to the live wire terminal of the charging plug, and the normally closed end is coupled to the switch side first end of the second relay;

[0008] The second relay, the control side is coupled to the controller through the second control circuit, and the second end of the switch side is coupled to the voltage division detection circuit;

[0009] The voltage division detection circuit includes a star circuit composed of at least three resistors, the first end of the star circuit is coupled to the second end of the switch side of the second relay, the second end is coupled to the reference voltage, and the third end is coupled to the controller.

[0010] The controller is used to control the opening or closing of the first relay through the first control circuit, control the opening or closing of the second relay through the second control circuit, and receive the output voltage of the voltage divider detection circuit when the second relay is open, and compare it with the preset voltage value to determine whether the charging plug is short-circuited.

[0011] Furthermore, the first control circuit includes a transistor Q1, whose collector is coupled to the first terminal of the control side of the first relay, its emitter is grounded, and its base is connected to the first signal output pin of the controller via a first current-limiting resistor R1; the second terminal of the control side of the first relay is coupled to the control voltage.

[0012] Furthermore, a TVS diode is coupled between the first terminal and the second terminal on the control side of the first relay.

[0013] Furthermore, the second control circuit includes a transistor Q2, whose collector is coupled to the first terminal of the control side of the second relay, its emitter is grounded, and its base is connected to the second signal output pin of the controller via the second current-limiting resistor R4; the second terminal of the control side of the second relay is coupled to the control voltage.

[0014] Furthermore, a TVS diode is coupled between the first and second terminals on the control side of the second relay.

[0015] Furthermore, the voltage divider detection circuit includes resistors R2, R3, and R5, wherein one end of resistors R2, R3, and R5 are connected together, the other end of resistor R2 is coupled to a reference voltage, the other end of resistor R3 is connected to the first signal input pin of the controller, and the other end of resistor R5 is connected to the second terminal of the second relay switch side.

[0016] Furthermore, a single-phase conducting diode D1 is coupled between the first terminal of the second relay switch side and the normally closed terminal of the first relay.

[0017] Furthermore, a fuse F1 is coupled between the common terminal of the first relay and the live wire terminal of the charging plug.

[0018] Furthermore, the preset voltage value is:

[0019] VA = 3.3 - (3.3 - V) F1 -V D1 )*R2 / (R2+R5)

[0020] Among them, V F1 V is the forward voltage drop of fuse F1. D1 R1 is the forward voltage drop of diode D1, R2 is the resistance of resistor R2, and R5 is the resistance of resistor R5.

[0021] When the second relay is opened, the controller receives the output voltage of the voltage division detection circuit, and when the output voltage is equal to the preset voltage value or the difference is within the preset range, it is determined that the charging plug has a short circuit.

[0022] Further, the controller is a single-chip microcomputer.

[0023] The non-isolated plug short circuit detection circuit of the utility model realizes the effective isolation of alternating voltage and direct current voltage based on two relays, reduces the production cost of the whole circuit. At the same time, it can adapt to chargers of different manufacturers, avoids the short circuit misjudgment caused by the small equivalent resistance of the input end of the charger, ensures that only when the output end is completely short-circuited, the feedback signal change is triggered, thereby improving the detection accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a circuit schematic diagram of the plug short circuit detection circuit embodiment of the utility model. DETAILED DESCRIPTION

[0025] Embodiments of the utility model will be described in more detail below with reference to the drawings. Although some embodiments of the utility model are shown in the drawings, it should be understood that the utility model can be realized in various forms, and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the utility model. It should be understood that the drawings and embodiments of the utility model are only for exemplary purposes, and are not used to limit the protection scope of the utility model.

[0026] The single resistor in the circuit schematic diagram can be replaced by a plurality of resistors in series or in parallel in the actual circuit, and the utility model is not limited to this.

[0027] In the specification and claims of the utility model, "coupling" includes direct connection and indirect connection, such as connection through an electrically conductive medium such as a conductor, wherein the electrically conductive medium can contain parasitic inductance or parasitic capacitance. It can also include connection through other active devices or passive devices on the basis of achieving the same or similar functional purposes, such as connection through switches, follower circuits, or other circuits or components.

[0028] In addition, the description of "first", "second" and the like in the present application is only for the purpose of description, and does not mean to particularly indicate the order or sequence, nor to limit the present application, which is only to distinguish the components or operations described by the same technical terms, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can be explicitly or implicitly included at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor in the protection scope required by the present application.

[0029] The embodiment of the present application provides a non-isolated plug short circuit detection circuit, which comprises:

[0030] The first relay is coupled to the controller through the first control circuit at the control side, and the normally open end of the switch side is coupled to the live wire of the power supply, the common end is coupled to the live wire terminal of the charging plug, and the normally closed end is coupled to the switch side first end of the second relay;

[0031] The second relay is coupled to the controller through the second control circuit at the control side, and the second end of the switch side is coupled to the voltage division detection circuit;

[0032] The voltage division detection circuit comprises a star circuit composed of at least three resistors, the first end of the star circuit is coupled to the second end of the switch side of the second relay, the second end is coupled to the reference voltage, and the third end is coupled to the controller;

[0033] And the controller is used for controlling the opening or closing of the first relay through the first control circuit, controlling the opening or closing of the second relay through the second control circuit, and receiving the output voltage of the voltage division detection circuit when the second relay is opened, and comparing with the preset voltage value to judge whether the charging plug is short-circuited.

[0034] Referring to Figure 1 As a preferred embodiment, in the embodiment, the first control circuit comprises a triode Q1, the collector of which is coupled to the control side first end of the first relay J1, the emitter is grounded, and the base is connected to the first signal output pin of the controller through the first current limiting resistor R1; the control side second end of the first relay J1 is coupled to a 12V control voltage.

[0035] As a further preferred embodiment, a TVS diode TVS1 is coupled between the control side first end and the second end of the first relay J1, which is used to provide a loop for the inductive reverse voltage of the coil when the relay is turned off to prevent the power supply from being broken down.

[0036] Referring to Figure 1As a preferred embodiment, in this embodiment, the second control circuit includes a transistor Q2, the collector of which is coupled to the first end of the control side of the second relay J2, the emitter is grounded, and the base is connected to the second signal output pin of the controller via the second current-limiting resistor R4; the second end of the control side of the second relay is coupled to the 12V control voltage.

[0037] As a further preferred embodiment, a TVS diode TVS1 is coupled between the first end and the second end of the control side of the second relay, for providing a loop for the induced reverse voltage of the coil when the relay is turned off, to prevent the power supply from being broken down.

[0038] Referring to Figure 1 As a preferred embodiment, in this embodiment, the voltage division detection circuit includes resistors R2, R3 and R5, wherein one end of the resistors R2, R3 and R5 is connected together, the other end of the resistor R2 is coupled to the 3.3V reference voltage, the other end of the resistor R3 is connected to the first signal input pin of the controller, and the other end of the resistor R5 is connected to the second end of the switch side of the second relay J2.

[0039] As a further preferred embodiment, a single-phase conduction diode D1 is coupled between the first end of the switch side of the second relay J2 and the normally closed end of the first relay J1, to prevent the large voltage of the live wire from flowing through the controller chip when misoperation occurs.

[0040] As a further preferred embodiment, a fuse F1 is coupled between the common end of the first relay J1 and the live wire terminal of the charging plug.

[0041] As a preferred embodiment, in this embodiment, the controller uses a single-chip microcomputer, and its working principle is well known to those skilled in the art, which will not be described in detail here.

[0042] As a preferred embodiment, in this embodiment, the preset voltage value for the controller to determine the short circuit is:

[0043] VA=3.3-(3.3-V F1 -V D1 )*R2 / (R2+R5)

[0044] wherein V F1 is the conduction voltage drop of the fuse F1, V D1 is the conduction forward voltage drop of the diode D1, R2 is the resistance value of the resistor R2, and R5 is the resistance value of the resistor R5.

[0045] When the second relay is turned on, the controller receives the output voltage of the voltage division detection circuit, and when the output voltage is equal to the preset voltage value or the difference is within the preset range, it is determined that the charging plug has a short circuit.

[0046] The working principle of the plug short circuit detection circuit in the embodiment is described further as follows:

[0047] Before the charging plug of the charging pile is used (power supply is provided), the common terminal of the relay J1 is connected with the normally closed terminal. The control J2 is closed, and the charging plug short circuit detection is started. At this time, the output voltage of the voltage division detection circuit (i.e. the voltage at DL_FB on the right side of the resistor R3) is read. If the plug is not short-circuited (zero fire line is not connected), the R5-D1-J1_5-J1_3-F1 circuit cannot form a loop, and at this time, the voltage at DL_FB is 3.3V reference voltage. On the contrary, if the plug is short-circuited (zero fire line is connected), the R5-D1-J1_5-J1_3-F1 circuit forms a loop, and since the resistance values of R2, R5, F1 and the forward conduction voltage of D1 are determined, if the plug is short-circuited, the signal input pin of the controller collects a voltage value of a fixed value VA, and at this time, it can be determined that the plug is short-circuited. When the charging plug is connected without short-circuit, the voltage VB at DL_FB read by the controller is between VA and the power supply voltage value. After the short circuit detection is completed, the relay J2 is disconnected, and at this time, the high-voltage alternating current and the low-voltage direct current are completely isolated.

[0048] The embodiments of the present application are intended to cover all such alternatives, modifications, and variations as fall within the broad scope of the appended claims. Accordingly, any and all such alternatives, modifications, equivalents, improvements and the like are intended to be encompassed by the present application.

Claims

1. A non-isolated plug short detection circuit, comprising: The application relates to a charger for charging a battery, which comprises: a first relay, the control side of which is coupled to a controller through a first control circuit, the normally open end of the switch side is coupled to a power supply live wire, the common end is coupled to the live wire terminal of a charging plug, and the normally closed end is coupled to the first end of the switch side of a second relay; a second relay, the control side of which is coupled to the controller through a second control circuit, and the second end of the switch side is coupled to a voltage division detection circuit; a voltage division detection circuit, which comprises a star circuit formed by at least three resistors, the first end of the star circuit is coupled to the second end of the switch side of the second relay, the second end is coupled to a reference voltage, and the third end is coupled to the controller; and a controller, which is used for controlling the opening or closing of the first relay through the first control circuit, controlling the opening or closing of the second relay through the second control circuit, and receiving the output voltage of the voltage division detection circuit when the second relay is opened, comparing the output voltage with a preset voltage value to determine whether the charging plug is short-circuited.

2. The non-isolated plug short detection circuit of claim 1, wherein, The first control circuit comprises a transistor Q1, the collector of which is coupled to the first end of the control side of the first relay, the emitter is grounded, and the base is connected to the first signal output pin of the controller through a first current-limiting resistor R1; the second end of the control side of the first relay is coupled to a control voltage.

3. The non-isolated plug short detection circuit of claim 2, wherein, A TVS diode one is coupled between the first end and the second end of the control side of the first relay.

4. The non-isolated plug short circuit detection circuit of claim 1, wherein, The second control circuit comprises a transistor Q2, the collector of which is coupled to the first end of the control side of the second relay, the emitter is grounded, and the base is connected to the second signal output pin of the controller through a second current-limiting resistor R4; the second end of the control side of the second relay is coupled to a control voltage.

5. The non-isolated plug short detection circuit of claim 4, wherein, A TVS diode two is coupled between the first end and the second end of the control side of the second relay.

6. The non-isolated plug short detection circuit of claim 4, wherein, The voltage division detection circuit comprises resistors R2, R3 and R5, one end of the resistors R2, R3 and R5 is connected together, the other end of the resistor R2 is coupled to a reference voltage, the other end of the resistor R3 is connected to the first signal input pin of the controller, and the other end of the resistor R5 is connected to the second end of the switch side of the second relay.

7. The non-isolated plug short detection circuit of claim 4, wherein, A single-phase conducting diode D1 is coupled between the first end of the switch side of the second relay and the normally closed end of the first relay.

8. The non-isolated plug short circuit detection circuit of claim 7, wherein, A fuse F1 is coupled between the common end of the first relay and the live wire terminal of the charging plug.

9. The non-isolated plug short circuit detection circuit of claim 8, wherein, The preset voltage value is: VA = 3.3 - (3.3 - V F1 -V D1 ) * R2 / (R2 + R5) wherein V F1 is the on voltage drop of the fuse F1, V D1 is the on forward voltage drop of the diode D1, R2 is the resistance value of the resistor R2, and R5 is the resistance value of the resistor R5. When the output voltage of the voltage division detection circuit received by the controller is equal to the preset voltage value or the difference is within a preset range when the second relay is opened, it is determined that the charging plug is short-circuited.

10. The non-isolated plug short circuit detection circuit of claim 9, wherein, The controller is a single-chip microcomputer.

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