A relay quick turn-off driving circuit

Abstract

The utility model provides a kind of relay quick cut-off drive circuit, belong to power electronics technical field. Including control unit, power supply unit, first switch unit, first resistance, second resistance, PNP triode, first relay and first unidirectional conducting unit, the power supply unit has the emitter of connecting the PNP triode, the collector of the PNP triode is connected the first relay input end, the first relay output end is connected between the first switch unit and first resistance. The base of the PNP triode is connected between the first resistance and second resistance, the first unidirectional conducting unit is parallel in first relay both ends, the first unidirectional conducting unit is from first relay output end to first relay input end unidirectional conduction. When applied to STS, the cut-off speed of relay can be improved, finally realizes the quick disconnection of inverter INV and power grid GRID.

Description

Technical Field

[0001] This utility model belongs to the field of power electronics technology and relates to a relay fast turn-off drive circuit. Background Technology

[0002] In existing technologies, STS (Static Transfer Switches) are used for rapid switching between grid and energy storage or off-grid systems. For example, when switching between grid-connected and off-grid modes, STS can ensure a seamless transition and prevent power outages. Currently, the static switching devices in STS modules use ATS contactors or thyristors as static transfer switches. ATS contactors are relatively large, and because they are mechanically disconnected, their travel is long, resulting in a disconnection time of up to 20ms. Thyristors, being semiconductor devices, although having a short turn-off time of 10ms, are prone to overheating and have high temperatures. Furthermore, without physical isolation measures, there is a risk that even if the thyristor fails, the circuit may still be in a conducting state, potentially leading to safety accidents. Utility Model Content

[0003] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a relay fast turn-off drive circuit.

[0004] This utility model proposes a relay fast turn-off drive circuit, including a control unit, a power supply unit, a first switching unit, a first resistor, a second resistor, a PNP transistor, a first relay, and a first unidirectional conduction unit;

[0005] The power supply unit is used to provide the power supply voltage. The power supply unit is connected in series with the second resistor, the first resistor, and the first switching unit to ground. The power supply unit is also connected to the emitter of the PNP transistor. The collector of the PNP transistor is connected to the input terminal of the first relay. The output terminal of the first relay is connected between the first switching unit and the first resistor. The base of the PNP transistor is connected between the first resistor and the second resistor. The first unidirectional conduction unit is connected in parallel across the first relay. The first unidirectional conduction unit conducts unidirectionally from the output terminal to the input terminal of the first relay.

[0006] The first switching unit is used to switch the current flowing through the first switching unit on and off;

[0007] The control unit is connected to the first switch unit and is used to control the on / off state of the first switch unit.

[0008] In the aforementioned relay fast turn-off drive circuit, the first switching unit is an NPN transistor.

[0009] In the aforementioned relay fast turn-off drive circuit, the collector of the NPN transistor is connected to the first resistor, the emitter of the NPN transistor is grounded, the base of the NPN transistor is connected to the control unit, a third resistor is connected between the base and emitter of the NPN transistor, and a fourth resistor is connected between the base of the NPN transistor and the control unit.

[0010] In the above-mentioned relay fast turn-off drive circuit, the power supply unit includes a pull-in voltage input terminal, a holding voltage input terminal, and a voltage output terminal. The pull-in voltage input terminal and the holding voltage output terminal are respectively connected to the voltage output terminal. The pull-in voltage input terminal provides a pull-in voltage, and the holding voltage input terminal provides a holding voltage. The pull-in voltage is higher than the holding voltage.

[0011] In the above-mentioned relay fast turn-off drive circuit, the power supply unit includes a second switching unit, a third unidirectional conduction unit, and a fourth unidirectional conduction unit. The second switching unit is used to switch the current flowing through the second switching unit. The pull-in voltage input terminal is connected in series with the third unidirectional conduction unit and the first switching unit to the voltage output terminal. The holding voltage input terminal is connected in series with the fourth unidirectional conduction unit between the first switching unit and the voltage output terminal.

[0012] In the above-mentioned relay fast turn-off drive circuit, the first relay includes a normally open contact switch and a normally closed contact switch.

[0013] When the relay is energized, it closes the normally open contact switch and opens the normally closed contact switch.

[0014] When the relay is released, the normally open contact switch is opened and the normally closed contact switch is closed.

[0015] The above-mentioned relay fast turn-off drive circuit also includes a second unidirectional conduction unit. The two ends of the second unidirectional conduction unit are respectively connected to the collector and emitter of the PNP transistor. The second unidirectional conduction unit conducts electricity unidirectionally from the collector to the emitter of the PNP transistor.

[0016] In the aforementioned relay fast turn-off drive circuit, the first unidirectional conduction unit is a transient voltage suppression diode.

[0017] In the aforementioned relay fast turn-off drive circuit, the second unidirectional conduction unit is a diode.

[0018] In the aforementioned relay fast turn-off drive circuit, a capacitor is also connected between the power supply unit and the base of the PNP transistor.

[0019] Compared with the prior art, this utility model, through the above-mentioned relay fast turn-off drive circuit, can improve the turn-off speed of the relay when applied to an STS that uses a relay as a turn-off switch, and ultimately achieve rapid disconnection of the inverter from the power grid. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a relay fast turn-off drive circuit according to an embodiment of this application;

[0021] Figure 2 This is a current flow diagram when the first switch unit of this application is closed;

[0022] Figure 3 This is a diagram showing the current flow of the power supply unit when the first switching unit is disconnected in an embodiment of this application.

[0023] Figure 4 This is a flow diagram of a small portion of the current discharged from the first relay to the PNP transistor when the first switching unit is disconnected in an embodiment of this application.

[0024] Figure 5 This is a diagram showing the flow direction of most of the discharge current from the first relay when the first switching unit is disconnected in an embodiment of this application.

[0025] In the diagram: 10, power supply unit; 20, first switch unit; 30, second switch unit. Detailed Implementation

[0026] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0027] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0028] like Figure 1As shown, the relay fast-turn-off drive circuit of this application embodiment includes: a control unit, a power supply unit 10, a first switching unit 20, a first resistor R1, a second resistor R2, a PNP transistor Q2, a first relay KM1, and a first unidirectional conduction unit; the power supply unit 10 is used to provide a power supply voltage, and the power supply unit 10 is connected in series with the second resistor R2, the first resistor R1, and the first switching unit 20 to ground. The power supply unit 10 is also connected to the emitter of the PNP transistor Q2, the collector of the PNP transistor Q2 is connected to the input terminal of the first relay KM1, and the output terminal of the first relay KM1 is connected between the first switching unit 20 and the first resistor R1; the base of the PNP transistor Q2 is connected between the first resistor R1 and the second resistor R2, and the first unidirectional conduction unit is connected in parallel across the first relay KM1, and the first unidirectional conduction unit conducts unidirectionally from the output terminal to the input terminal of the first relay KM1; the first switching unit 20 is used to switch the current flowing through the first switching unit 20; the control unit is connected to the first switching unit 20 and is used to control the switching of the first switching unit 20.

[0029] In this embodiment of the application, the control unit can control the on / off state of the first switching unit 20. Since the current path from the power supply unit 10 to ground is controlled only by the first switching unit 20, when the first switching unit 20 is turned on and when the power supply unit 10 has a power supply voltage, the current output from the power supply unit 10 can flow through the first switching unit 20 to ground.

[0030] Specifically, when the first switching unit 20 is in the off state for a long time, the voltage between the second resistor R2 and the first resistor R1, that is, the voltage of the base of the PNP transistor Q2, is equal to the voltage of the emitter of the PNP transistor Q2, both of which are the supply voltage of the power supply unit 10. At this time, the PNP transistor Q2 is in the cut-off state.

[0031] See Figure 2 When the first switching unit 20 is turned on and the power supply unit 10 has a supply voltage, the power supply unit 10 first forms a path from the second resistor R2, the first resistor R1, the first switching unit 20 to ground, and the current flows through the second resistor R2, the first resistor R1, the first switching unit 20 to ground. At this time, the voltage between the second resistor R2 and the first resistor R1 is pulled down, that is, the voltage of the base of the PNP transistor Q2 is pulled down, and the voltage difference between the emitter and the base of the PNP transistor Q2 is greater than the cutoff voltage of the PNP transistor Q2, so the PNP transistor Q2 turns on. After the PNP transistor Q2 turns on, the power supply unit 10 forms a path from the PNP transistor Q2, the first relay KM1, the first switching unit 20 to ground, and the supply voltage provided by the power supply unit 10 energizes and engages the first relay KM1.

[0032] See Figure 3When the first switching unit 20 is switched off, the path from the PNP transistor Q2, the first relay KM1, the first switching unit 20 to ground is disconnected. The power supply unit 10 stops supplying power to the first relay KM1. The coil of the first relay KM1 generates an induced electromotive force. The induced electromotive force forms a discharge current in the circuit. A small portion of the discharge current flows through the first resistor R1 first, raising the voltage at the base of the PNP transistor Q2.

[0033] Reference Figure 4 Meanwhile, the power supply voltage of the power supply unit 10 also raises the voltage of the base of the PNP transistor Q2 through the second resistor R2 until the base voltage is raised to be equal to the power supply voltage. At this time, the voltage difference between the emitter and base of the PNP transistor Q2 is 0, and the PNP transistor Q2 is turned off.

[0034] Combination Figure 3 and Figure 4 Because a small portion of the discharge current of the first relay KM1 and the output current of the power supply unit simultaneously raise the base voltage of the PNP transistor Q2, the base voltage rises faster and for a shorter time, and the cutoff time of the PNP transistor Q2 is shorter.

[0035] See Figure 5 When the PNP transistor Q2 is turned off, most of the discharge current generated by the induced electromotive force flows from the first relay KM1 terminal through the first unidirectional conducting element and returns to the first relay KM1, forming a discharge circuit. The discharge current discharges energy through the first unidirectional conducting element.

[0036] The relay fast turn-off drive circuit provided in this application rapidly raises the voltage at the base of the PNP transistor Q2 by the discharge current generated by the first relay KM1 when the first switching unit 20 is turned off, causing the PNP transistor Q2 to turn off quickly. This quickly forms a discharge current discharge circuit from the first relay KM1 to the first unidirectional conduction unit, thereby rapidly releasing the induced electromotive force of the coil of the first relay KM1 and causing the first relay KM1 to release quickly.

[0037] As an optional implementation, the first switching unit 20 is an NPN transistor Q1.

[0038] In the embodiments of this application, the function of the first switching unit 20 is to switch the current in its current path on and off. Therefore, in addition to using an NPN transistor Q1, the first switching unit 20 can also be replaced by electronic components such as a PNP transistor, MOSFET, IGBT, thyristor, optocoupler, etc., or by a circuit with the same function.

[0039] As an optional implementation, the collector of NPN transistor Q1 is connected to a first resistor R1, the emitter of NPN transistor Q1 is grounded, the base of NPN transistor Q1 is connected to the control unit, a third resistor R3 is connected between the base and emitter of NPN transistor Q1, and a fourth resistor R4 is connected between the base of NPN transistor Q1 and the control unit.

[0040] In the embodiments of this application, the fourth resistor R4 limits the base current of the NPN transistor Q1 to prevent excessive current from damaging the NPN transistor Q1. The third resistor R3 is a pull-down resistor. When the high-level signal of the NPN transistor Q1 is disconnected, the third resistor R3 pulls the base voltage to ground, ensuring that the NPN transistor Q1 is reliably turned off. The control unit can output high and low levels. When the output is high, the NPN transistor Q1 is turned on. The output voltage of the power supply unit 10 forms a current path to ground through the second resistor R2, the first resistor R1, and the NPN transistor Q1. The voltage between the first resistor R1 and the second resistor R2 is pulled low, that is, the base voltage of the PNP transistor Q2 is pulled low, and the PNP transistor Q2 is turned on.

[0041] As an optional implementation, the power supply unit 10 includes a pull-in voltage input terminal U1 and a holding voltage input terminal U2. The pull-in voltage input terminal U1 and the holding voltage output terminal U2 are respectively connected to the voltage output terminal Uo. The pull-in voltage input terminal U1 provides the pull-in voltage, and the holding voltage input terminal U2 provides the holding voltage. The pull-in voltage is higher than the holding voltage.

[0042] In the embodiments of this application, the pull-in voltage value can change the first relay KM1 from the released state to the pulled-in state. In order to reliably pull in the first relay KM1, the pull-in voltage is higher than the holding voltage, while the holding voltage can keep the first relay KM1 pulled in when it is in the pulled-in state. Since the holding voltage is lower than the pull-in voltage, maintaining the pulled-in state of the first relay KM1 by the pull-in voltage can reduce power consumption.

[0043] As an optional implementation, the power supply unit 10 includes a second switching unit 30, a third unidirectional conduction unit, and a fourth unidirectional conduction unit. The second switching unit is used to switch the current flowing through the second switching unit. The voltage input terminal U1 is connected in series with the third unidirectional conduction unit and the first switching unit 20 to the voltage output terminal Uo. The voltage input terminal U2 is connected in series with the fourth unidirectional conduction unit between the first switching unit 20 and the voltage output terminal Uo.

[0044] In the embodiments of this application, the voltage at the pull-in voltage input terminal U1 is the input voltage, and the voltage at the holding voltage input terminal U2 is the holding voltage. When the second switch unit 30 is closed, both the pull-in voltage input terminal U1 and the holding voltage input terminal U2 are connected to the voltage output terminal Uo. Since the pull-in voltage is higher than the holding voltage, the voltage output at the voltage output terminal Uo is the pull-in voltage. When the second switch unit 30 is open, only the holding voltage input terminal U2 is connected to the voltage output terminal Uo, and the voltage at the voltage output terminal Uo is the holding voltage. The third unidirectional conduction unit is a diode D3, and the fourth unidirectional conduction unit is a diode D4, which can prevent current reverse flow. The second switch unit 30 is composed of an NPN transistor Q3, a second relay KM2, a diode D5, a fifth resistor R5, a sixth resistor R6, etc. The second switch unit 30 is a conventional drive circuit. By inputting a high level to the NPN transistor Q3 through the fifth resistor R5, the NPN transistor Q3 is turned on, the second relay KM2 is closed, and a path is formed between the pull-in voltage input terminal U1 and the voltage output terminal Uo. In other embodiments, the second switching unit 30 may also be replaced by other electronic components or circuits with the same function.

[0045] As an optional implementation, the first relay KM1 includes a normally open contact switch and a normally closed contact switch; when the first relay KM1 is energized, the normally open contact switch is closed and the normally closed contact switch is open; when the first relay KM1 is released, the normally open contact switch is open and the normally closed contact switch is closed.

[0046] In the embodiments of this application, the normally open contact switch is located in the current path between the grid GRID and the inverter INV, and the normally closed contact switch is located between the power supply U3 and the relay detection circuit (not shown in the figure, the relay detection circuit is connected to the TEST terminal in the figure). The relay detection circuit contains an indicator light. When the first relay KM1 is in the energized state, the normally closed contact switch opens, and the indicator light goes out, indicating that the first relay KM1 is working normally. If the indicator light remains lit at this time, then the first relay KM1 is malfunctioning.

[0047] As an optional implementation, the first unidirectional conduction unit is a transient voltage suppression diode D1, and the second unidirectional conduction unit is a diode D2.

[0048] In the embodiments of this application, the second unidirectional conduction unit of diode D2 protects PNP transistor Q2. The first unidirectional conduction unit uses transient voltage suppression diode D1. When the first relay KM1 discharges current, transient voltage suppression diode D1 provides protection by quickly clamping high voltage spikes and efficiently absorbing energy through a protection circuit. Compared with traditional freewheeling diodes, it has higher response speed and clamping accuracy.

[0049] As an optional implementation, a capacitor C1 is also connected between the power supply unit 10 and the base of the PNP transistor Q2.

[0050] In the embodiments of this application, capacitor C1 is used to filter out interference and prevent the first relay KM1 from malfunctioning when it is energized. And when the first relay KM1 is released to quickly turn off, it prevents the charge potential from breaking down the PNP transistor Q2, thus avoiding damage to the PNP transistor Q2.

[0051] By using the above relay fast shutdown drive circuit, when applied to an STS that uses a relay as a shutdown switch, the shutdown speed of the relay can be improved, ultimately achieving rapid disconnection between the inverter INV and the grid GRID.

[0052] It should be noted that in this utility model, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly defined. The terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly defined. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0053] Furthermore, the technical solutions of the various embodiments of this utility model can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0054] The specific embodiments described herein are merely illustrative examples of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from this utility model or exceeding the scope defined by the appended claims.

Claims

1. A relay fast turn-off drive circuit, characterized in that, include: Control unit, power supply unit, first switch unit, first resistor, second resistor, PNP transistor, first relay and first unidirectional conduction unit; The power supply unit is used to provide the power supply voltage. The power supply unit is connected in series with the second resistor, the first resistor, and the first switching unit to ground. The power supply unit is also connected to the emitter of the PNP transistor. The collector of the PNP transistor is connected to the input terminal of the first relay. The output terminal of the first relay is connected between the first switching unit and the first resistor. The base of the PNP transistor is connected between the first resistor and the second resistor. The first unidirectional conduction unit is connected in parallel across the first relay. The first unidirectional conduction unit conducts unidirectionally from the output terminal to the input terminal of the first relay. The first switching unit is used to switch the current flowing through the first switching unit on and off; The control unit is connected to the first switch unit and is used to control the on / off state of the first switch unit.

2. The relay fast turn-off drive circuit according to claim 1, characterized in that, The first switching unit is an NPN transistor.

3. The relay fast turn-off drive circuit according to claim 2, characterized in that, The collector of the NPN transistor is connected to the first resistor, the emitter of the NPN transistor is grounded, the base of the NPN transistor is connected to the control unit, a third resistor is connected between the base and emitter of the NPN transistor, and a fourth resistor is connected between the base and the control unit.

4. The relay fast turn-off drive circuit according to claim 1, characterized in that, The power supply unit includes a pull-in voltage input terminal, a holding voltage input terminal, and a voltage output terminal. The pull-in voltage input terminal and the holding voltage output terminal are respectively connected to the voltage output terminal. The pull-in voltage input terminal provides a pull-in voltage, and the holding voltage input terminal provides a holding voltage. The pull-in voltage is higher than the holding voltage.

5. A relay fast turn-off drive circuit according to claim 4, characterized in that, The power supply unit includes a second switching unit, a third unidirectional conduction unit, and a fourth unidirectional conduction unit. The second switching unit is used to switch the current flowing through the second switching unit. The pull-in voltage input terminal is connected in series with the third unidirectional conduction unit and the first switching unit to the voltage output terminal. The holding voltage input terminal is connected in series with the fourth unidirectional conduction unit between the first switching unit and the voltage output terminal.

6. The relay fast turn-off drive circuit according to claim 1, characterized in that, The first relay includes a normally open contact switch and a normally closed contact switch; When the first relay is energized, the normally open contact switch is closed, and the normally closed contact switch is open. When the first relay is released, the normally open contact switch opens and the normally closed contact switch closes.

7. A relay fast turn-off drive circuit according to claim 1, characterized in that, It also includes a second unidirectional conduction unit, the two ends of which are respectively connected to the collector and emitter of the PNP transistor, and the second unidirectional conduction unit conducts electricity unidirectionally from the collector to the emitter of the PNP transistor.

8. A relay fast turn-off drive circuit according to claim 1, characterized in that, The first unidirectional conduction unit is a transient voltage suppression diode.

9. A relay fast turn-off drive circuit according to claim 7, characterized in that, The second unidirectional conduction unit is a diode.

10. A relay fast turn-off drive circuit according to claim 1, characterized in that, A capacitor is also connected between the power supply unit and the base of the PNP transistor.

Images