A switching capacitor zero-crossing circuit controlled by a relay-controlled diode

Abstract

The utility model relates to relay technology field discloses a kind of switching capacitor zero-crossing circuit of relay control diode conduction, including zero-crossing detection circuit, and the zero-crossing detection circuit electrically connected has power grid and control module, and the control module electrically connected has magnetic latching relay and electric latching relay, and the other end of the magnetic latching relay electrically connected has capacitor, and the one end of the capacitor electrically connected in the other end of power grid, and the other end of the electric latching relay electrically connected has unidirectional conduction ware group, and the other end of the unidirectional conduction ware group and capacitor electrically connected. In the utility model, by zero-crossing detection circuit, power grid, control module, electric latching relay, magnetic latching relay, unidirectional conduction ware group and capacitor, to solve the moment of capacitor input due to environmental influence not at voltage zero point, produce inrush current, and then lead to device life rapidly ageing, affect product overall stability problem.

Description

Technical Field

[0001] This utility model relates to the field of relay technology, and in particular to a zero-crossing circuit for switching capacitors by controlling the conduction of a relay diode. Background Technology

[0002] When a capacitor is connected to the power grid, it will generate inrush current of different magnitudes depending on the phase angle at which it is connected. If the capacitor is connected at a random phase angle, it may generate a large inrush current, which will have a significant impact on the power system, capacitor lifespan, and equipment safety.

[0003] Currently, capacitor switching mechanisms generally use synchronous switches with magnetic latching relays as the core. For synchronous switches that control capacitor switching, they must close when the voltage is zero, so as to achieve capacitor switching without inrush current.

[0004] Although synchronous switches utilize power electronics technology to achieve millisecond-level precision in switching timing, magnetic latching relays are mechanical switches. Their operating time varies with increasing temperature, humidity, and usage frequency. This can cause the capacitor to be engaged at a time when the voltage is not at zero, resulting in inrush current. Consequently, this leads to rapid aging of the device and affects the overall stability of the product. Utility Model Content

[0005] To overcome the above deficiencies, this utility model provides a zero-crossing circuit for switching capacitors by controlling the conduction of a relay diode. It aims to solve the problem that the capacitor is switched on at a time when the voltage is not zero due to environmental influences, resulting in inrush current, which in turn leads to rapid aging of the device and affects the overall stability of the product.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a zero-crossing circuit for switching a capacitor by controlling the conduction of a relay diode, comprising a zero-crossing detection circuit, wherein the zero-crossing detection circuit is electrically connected to a power grid and a control module, the control module is electrically connected to a magnetic latching relay and an electric latching relay, one end of each of the magnetic latching relay and the electric latching relay is electrically connected to one end of the power grid, the other end of the magnetic latching relay is electrically connected to a capacitor, one end of the capacitor is electrically connected to the other end of the power grid, and the other end of the electric latching relay is electrically connected to a unidirectional conduction group, the unidirectional conduction group being electrically connected to the capacitor.

[0007] Preferably, the unidirectional conduction group includes diode A and diode B, the anode of diode B is electrically connected to one end of a capacitor, the cathode of diode B is electrically connected to the cathode of diode A, the anode of diode A is electrically connected to one end of an electrically holding relay, and the cathodes of diode B and diode A are both electrically connected to the other end of the electrically holding relay.

[0008] Preferably, the control module includes a state detection circuit and a control circuit. The control circuit is electrically connected to the zero-crossing detection circuit, the state detection circuit, the electric holding relay, and the magnetic holding relay. The state detection circuit is electrically connected to the electric holding relay and the magnetic holding relay.

[0009] Preferably, the control terminals of both the electric latching relay and the magnetic latching relay are electrically connected to the control circuit via a drive circuit.

[0010] Preferably, the electrically holding relay, the unidirectional conduction group, and the capacitor are connected in series and then in parallel on the neutral and live wires of the power grid to form a circuit branch.

[0011] Preferably, the magnetic latching relay is connected in series with the capacitor and then in parallel to the neutral and live wires of the power grid to form the main circuit.

[0012] Preferably, the zero-crossing detection circuit is connected in parallel to the neutral and live wires of the power grid.

[0013] Preferably, the capacitor is an AC capacitor and the control circuit is a microprocessor.

[0014] This utility model has the following beneficial effects: 1. In this utility model, the zero-crossing signal in the power grid is detected in real time by the zero-crossing detection circuit and transmitted to the control module. The control module controls the opening and closing of the electric latching relay and the magnetic latching relay. The current in the power grid is cut off by the unidirectional conduction group, thereby realizing the non-current closing of the magnetic latching relay. With the cooperation of the capacitor, the problem of inrush current caused by the capacitor being connected at a time when the voltage is not zero due to environmental influences is solved, which leads to rapid aging of the device and affects the overall stability of the product.

[0015] 2. In this utility model, the opening and closing of the electrically holding relay is controlled by the control module, and the function of cutting off the current of the unidirectional conductor group is realized by connecting the cathode of diode B and the cathode of diode A, connecting the anode of diode B and the capacitor, and connecting the two poles of diode A and the two ends of the electrically holding relay. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a partial module architecture of a relay-controlled diode switching capacitor zero-crossing circuit proposed in this utility model. Figure 2 This is a schematic diagram of a unidirectional conductor group architecture for a relay-controlled diode switching capacitor zero-crossing circuit proposed in this utility model. Figure 3 This is a schematic diagram of the control module architecture of a capacitor zero-crossing circuit for relay-controlled diode conduction proposed in this utility model. Figure 4 This is a schematic diagram of the driving circuit for a relay-controlled diode switching capacitor zero-crossing circuit proposed in this utility model. Figure 5 This is a partial circuit diagram of a capacitor zero-crossing circuit for controlling diode conduction by a relay, as proposed in this utility model. Figure 6 This is a schematic diagram of a state detection circuit for a capacitor zero-crossing circuit controlled by a relay to turn on the diode, as proposed in this utility model. Detailed Implementation

[0017] The technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0018] Reference Figure 1 and Figure 5 This utility model provides an embodiment of a capacitor switching zero-crossing circuit for controlling diode conduction via a relay, comprising a zero-crossing detection circuit, wherein the zero-crossing detection circuit is electrically connected to a power grid and a control module, the control module is electrically connected to a magnetic latching relay and an electric latching relay, one end of each of the magnetic latching relay and the electric latching relay is electrically connected to one end of the power grid, the other end of the magnetic latching relay is electrically connected to a capacitor, one end of the capacitor is electrically connected to the other end of the power grid, and the other end of the electric latching relay is electrically connected to a unidirectional conduction group, the unidirectional conduction group being electrically connected to the capacitor.

[0019] Specifically, the power grid is alternating current. When the voltage is in the positive half-cycle, the current flows out from the live wire of the power grid, passes through the load, and returns to the neutral wire, forming a current in one direction. When the voltage is in the negative half-cycle, the current direction is reversed, flowing out from the neutral wire of the power grid, passing through the load, and returning to the live wire.

[0020] The zero-crossing detection circuit detects the zero-crossing signal in the power grid in real time and transmits it to the control module for processing and analysis. At this time, the voltage in the power grid is close to zero. The control module controls the electric holding relay to close. Through the action of the unidirectional conduction group, a current cut-off state is formed. At this time, the circuit formed by the electric holding relay, capacitor and power grid is conducting, but there is no current at its two ends. This avoids the inrush current caused by environmental factors, such as the capacitor being connected at a time when the voltage is not zero, or the inrush current impact that should have been caused by a small voltage or phase difference between the capacitor and the power grid. Thus, the unidirectional conduction group blocks the inrush current.

[0021] After the electrically latching relay stabilizes, the control module then controls the magnetically latching relay to close. At this point, because the unidirectional conductor group in the circuit formed by the electrically latching relay has blocked the current, there is no voltage difference or current across the contacts of the magnetically latching relay. This achieves zero-current closure of the magnetically latching relay, avoiding instantaneous surges and ensuring that the voltage of the circuit formed by the power grid, the magnetically latching relay, and the capacitor, as well as the voltage in the power grid, are all zero. During this process, the control module monitors the status of the electrically latching and magnetically latching relays in real time. After the magnetically latching relay stabilizes, the control module controls the electrically latching relay to open, thus enabling the capacitor voltage to rise synchronously with the rise of the power grid voltage. This solves the problem that environmental factors can cause the capacitor to be engaged at a time when the voltage is not at zero, resulting in inrush current, which leads to rapid aging of the device and affects the overall stability of the product.

[0022] Reference Figure 1 and Figure 2 The unidirectional conduction group includes diode A and diode B. The anode of diode B is electrically connected to one end of a capacitor, the cathode of diode B is electrically connected to the cathode of diode A, the anode of diode A is electrically connected to one end of an electrically holding relay, and the cathodes of diode B and diode A are both electrically connected to the other end of the electrically holding relay.

[0023] Specifically, diodes A and B can be fast recovery diodes, such as germanium diodes or Schottky diodes. Initially, the electrically holding relay is open, disconnecting the path between the relay and diode B. At this time, the current from diode B to diode A is also blocked due to diode A's cutoff. When the electrically holding relay receives a zero-crossing signal, it closes. At this point, a loop is formed between diode B, the electrically holding relay, diode A, and diode B. However, because this is at the zero-crossing moment, the current in the loop is extremely small, and there is no inrush current. This achieves the function of mutually blocking current conduction between diodes A and B, thus realizing the function of current cutoff for the unidirectional conduction group.

[0024] Reference Figure 3 and Figure 6 The control module includes a state detection circuit and a control circuit. The control circuit is electrically connected to the zero-crossing detection circuit, the state detection circuit, the electric holding relay, and the magnetic holding relay. The state detection circuit is electrically connected to the electric holding relay and the magnetic holding relay.

[0025] Specifically, the state detection circuit measures the opening and closing status of the electric and magnetic latching relays in real time and transmits the status to the control circuit for analysis and processing. Combined with the zero-crossing detection circuit, the zero-crossing signal of the power grid is detected in real time and transmitted to the control circuit, so that the control circuit controls the electric and magnetic latching relays to open and close, thereby realizing the intelligent control of the zero-crossing circuit to prevent inrush current.

[0026] Reference Figure 3 and Figure 4 The control terminals of both the electric latching relay and the magnetic latching relay are electrically connected to the control circuit via a drive circuit.

[0027] Specifically, the control circuit transmits commands and signals to the drive circuit, and the drive circuit can drive the electric latching relay and the magnetic latching relay to realize the control of the main circuit by weak current signals.

[0028] Reference Figure 1 The electrically holding relay, the unidirectional conduction group, and the capacitor are connected in series and then in parallel to the neutral and live wires of the power grid to form a circuit branch.

[0029] Specifically, by connecting the electrically holding relay, the unidirectional conduction group, and the capacitor in series and then in parallel to the power grid to form a branch, the inrush current is cut off. This achieves the effect that the capacitor is not connected at the zero voltage point, or that the small voltage or phase difference between the capacitor and the power grid, which should have caused an inrush current impact on the capacitor, is blocked by the unidirectional conduction group and no longer causes an inrush current impact on the capacitor.

[0030] Reference Figure 1 The magnetic latching relay is connected in series with a capacitor and then in parallel to the neutral and live wires of the power grid to form the main circuit.

[0031] Specifically, the magnetic latching relay is connected in series with the capacitor and then in parallel to the power grid to form the main circuit of the zero-crossing circuit, thereby realizing the switching function of the zero-crossing circuit.

[0032] Reference Figure 1 The zero-crossing detection circuit is connected in parallel to the neutral and live wires of the power grid.

[0033] Specifically, the zero-crossing detection circuit has a filtering function. By connecting the zero-crossing detection circuit in parallel with the power grid, it can realize the function of real-time detection of the power grid's zero-crossing signal.

[0034] Reference Figure 3 The capacitor is an AC capacitor, and the control circuit is a microprocessor.

[0035] Specifically, by designing the capacitor as an AC capacitor, a stable match between the zero-crossing circuit and the AC power grid is achieved. The control circuit enables the microprocessor to process and analyze signals from various modules and send instructions.

[0036] Working principle: When the voltage of the power grid is not zero, the electric holding relay is in the open state. At this time, the electric holding relay and diode B are disconnected, and the path from diode B to diode A is also closed. Then, the zero-crossing detection circuit detects the zero-crossing signal in the power grid and transmits it to the control module for processing and analysis. The control module controls the electric holding relay to close. At this time, the current forms a loop from diode B—relay—diode A—diode B. However, because this is the zero-crossing moment, the current in the loop is extremely small and there is no inrush current, thus forming a current cutoff state. At this time, the loop formed by the electric holding relay, capacitor, and power grid is conductive, but there is no current at its two ends, thus avoiding the impact of inrush current on the capacitor.

[0037] After the electrically latching relay has stabilized, the control module then controls the magnetically latching relay to close. At this point, because the unidirectional conductor group in the circuit formed by the electrically latching relay has blocked the current, there is no voltage difference or current across the contacts of the magnetically latching relay. This achieves current-free closure of the magnetically latching relay, avoiding instantaneous surges. This solves the problem that environmental factors can cause the capacitor to be engaged at a time when the voltage is not zero, resulting in inrush current, which in turn leads to rapid aging of the device and affects the overall stability of the product.

[0038] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A zero-crossing circuit for switching a capacitor by controlling the conduction of a diode via a relay, comprising a zero-crossing detection circuit, characterized in that: The zero-crossing detection circuit is electrically connected to the power grid and the control module. The control module is electrically connected to a magnetic latching relay and an electric latching relay. One end of each of the magnetic latching relay and the electric latching relay is electrically connected to one end of the power grid. The other end of the magnetic latching relay is electrically connected to a capacitor. One end of the capacitor is electrically connected to the other end of the power grid. The other end of the electric latching relay is electrically connected to a unidirectional conduction group. The unidirectional conduction group is electrically connected to the other end of the capacitor.

2. The zero-crossing capacitor switching circuit for relay-controlled diode conduction according to claim 1, characterized in that: The unidirectional conduction group includes diode A and diode B. The anode of diode B is electrically connected to one end of a capacitor, the cathode of diode B is electrically connected to the cathode of diode A, the anode of diode A is electrically connected to one end of an electrically holding relay, and the cathodes of diode B and diode A are both electrically connected to the other end of the electrically holding relay.

3. The zero-crossing capacitor switching circuit for relay-controlled diode conduction according to claim 1, characterized in that: The control module includes a state detection circuit and a control circuit. The control circuit is electrically connected to the zero-crossing detection circuit, the state detection circuit, the electric holding relay, and the magnetic holding relay. The state detection circuit is electrically connected to the electric holding relay and the magnetic holding relay.

4. The zero-crossing capacitor switching circuit for relay-controlled diode conduction according to claim 3, characterized in that: The control terminals of both the electric latching relay and the magnetic latching relay are electrically connected to the control circuit via a drive circuit.

5. The zero-crossing capacitor switching circuit for relay-controlled diode conduction according to claim 1, characterized in that: The electrically holding relay, unidirectional conduction group, and capacitor are connected in series and then in parallel to the neutral and live wires of the power grid to form a circuit branch.

6. The zero-crossing capacitor switching circuit for relay-controlled diode conduction according to claim 1, characterized in that: The magnetic latching relay is connected in series with a capacitor and then in parallel to the neutral and live wires of the power grid to form the main circuit.

7. The zero-crossing capacitor switching circuit for relay-controlled diode conduction according to claim 1, characterized in that: The zero-crossing detection circuit is connected in parallel to the neutral and live wires of the power grid.

8. The zero-crossing capacitor switching circuit for relay-controlled diode conduction according to claim 3, characterized in that: The capacitor is an AC capacitor, and the control circuit includes a microprocessor.

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