Low-voltage direct-current driving circuit of voltage self-adaptive alternating-current contactor
By driving the AC contactor through a low-voltage power supply circuit and a current limiting circuit, the reliability problem under low-voltage ride-through conditions is solved, a simple and efficient driving method is achieved, costs are reduced and the stability of the power system is improved.
Patent Information
- Application Number
- CN202422802704.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-09-26
- Estimated Expiration
- 2034-11-18
AI Technical Summary
Existing AC contactors are difficult to drive reliably under low voltage ride-through conditions, resulting in unstable power systems. Existing solutions are costly, complex in structure, and have low energy efficiency.
It adopts low-voltage power supply circuit, boost circuit and current limiting circuit, provides DC power through low-voltage auxiliary power supply, drives AC contactor after boosting, and maintains its closed state through current limiting circuit, simplifying it to single-channel output.
The reliable driving of the AC contactor under low voltage conditions is achieved, which reduces costs, simplifies the circuit structure, and improves system efficiency and reliability.
Smart Images
Figure CN223390448U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of AC contactors, and in particular relates to a voltage-adaptive AC contactor low-voltage DC drive circuit. Background Art
[0002] AC contactors are key components in power systems, enabling remote control and frequently operated loads to be connected and disconnected in circuits. Traditionally, AC contactors rely on 220V AC power to ensure stable closing and closing operations. However, in practical applications, particularly during grid faults or voltage dips (so-called low voltage ride-through conditions), the 220V AC power supply may experience brief interruptions. Such interruptions can result in the AC contactor being unable to obtain sufficient holding current, potentially causing it to disconnect unexpectedly, impacting the normal operation of the entire power system.
[0003] Existing technology offers a solution to this problem: integrating a low-voltage auxiliary power supply into the AC contactor's power supply system. This low-voltage auxiliary power supply can continue to provide stable power support during grid voltage drops or interruptions, ensuring that the AC contactor remains closed even during low-voltage ride-through conditions. This approach effectively improves the reliability and stability of the power system and reduces unplanned downtime caused by voltage fluctuations.
[0004] Despite this, existing solutions still have certain limitations. For example, existing technology includes a specially designed DC control circuit for AC contactors that can simultaneously output one high voltage and one low voltage, and uses a complex switching mechanism to control the startup and maintenance of the AC contactor. While this method solves the problem of maintaining the AC contactor during low-voltage ride-through to a certain extent, its complex design increases the overall cost of the system and may also reduce the reliability and ease of maintenance. In addition, the need for additional circuitry to switch between high and low voltages not only increases the size of the equipment but also may lead to reduced energy efficiency.
[0005] In summary, while existing technical solutions can, to a certain extent, address the issue of maintaining AC contactors during LVRT, these solutions generally suffer from drawbacks such as high cost, complex structure, and low energy efficiency. Therefore, developing a simple, efficient, and economical AC contactor power supply drive technology is of great practical significance for improving the overall performance of power systems. Utility Model Content
[0006] This utility model aims to solve the problem of reliably driving an AC contactor when the AC 220V voltage is unstable. Therefore, a voltage-adaptive low-voltage DC drive circuit for an AC contactor is proposed. This utility model utilizes the power system's low-voltage auxiliary power supply as the AC contactor's power source. A boost circuit outputs a high voltage to drive the contactor, which is then adaptively reduced to a voltage sufficient to maintain contactor closure via a current limiting circuit, achieving both drive and maintenance of the AC contactor. This utility model has only one output interface and eliminates the need for switching circuits, resulting in lower costs and a simpler operating mode compared to existing solutions.
[0007] The utility model adopts the following technical solutions to achieve the purpose:
[0008] A voltage-adaptive AC contactor low-voltage DC drive circuit comprises a low-voltage power supply circuit, a boost circuit and a current limiting circuit connected in sequence; the low-voltage power supply circuit is connected to a low-voltage auxiliary power supply, receives a first DC power input from the low-voltage auxiliary power supply, and outputs the first DC power to the boost circuit; the boost circuit converts the first DC power into a second DC power and outputs the second DC power to the current limiting circuit, wherein the voltage of the first DC power is lower than that of the second DC power; the current limiting circuit is connected to an AC contactor, and is used to store the second DC power and, when the AC contactor is put into operation, drives the AC contactor via the second DC power and maintains the power supply of the AC contactor.
[0009] Specifically, the low-voltage power supply circuit includes a low-voltage input bus capacitor C1 and a switch tube Q1; the low-voltage input bus capacitor C1 is used to provide ripple current support for the boost circuit, and the switch tube Q1 is used to provide excitation for the boost circuit through its own controlled breaking mode.
[0010] Specifically, the boost circuit is implemented by using a transformer T1; the low-voltage auxiliary power supply DC is sequentially connected to the primary winding of the transformer T1 and the switch tube Q1 to form a series loop.
[0011] Specifically, the input bus capacitor C1 is connected in parallel with the low-voltage auxiliary power supply DC.
[0012] Specifically, the switch tube Q1 is implemented by a MOS tube, and the switching of the MOS tube provides excitation for the primary winding of the transformer T1.
[0013] Specifically, the current limiting circuit includes an output rectifier diode D1, an output bus capacitor C2, and a current sampling resistor R1; the output bus capacitor C2 has a preset voltage threshold, and the secondary winding of the transformer T1 outputs a second DC power through the rectifier diode D1 to charge the output bus capacitor C2 until it reaches the preset voltage threshold; the output bus capacitor C2 is used to provide the current required for the AC contactor to start and close, and the current sampling resistor R1 is used to limit and maintain the current required for the AC contactor to remain closed.
[0014] Specifically, the secondary winding of the transformer T1 is sequentially connected to the rectifier diode D1 , the output bus capacitor C2 , and the current sampling resistor R1 to form a series loop.
[0015] Specifically, the coil K1 of the AC contactor is connected in parallel with the output bus capacitor C2.
[0016] Specifically, an output switch S1 is further provided in the parallel circuit of the coil K1 of the AC contactor and the output bus capacitor C2.
[0017] Specifically, the load current of the coil K1 of the AC contactor is greater than the output current of the transformer T1 limited by the current sampling resistor R1.
[0018] In summary, due to the adoption of this technical solution, the beneficial effects of the present utility model are as follows:
[0019] This utility model uses capacitor energy storage to provide the necessary high-voltage pulse current for closing the AC contactor, ensuring that the contactor can quickly and reliably complete the pull-in operation. Furthermore, by providing a current sampling resistor, the current required to maintain the contactor's closed state is precisely controlled, ensuring the contactor's stability and safety during long-term operation. The entire circuit design utilizes a low-voltage DC input and a single-output structure, which not only simplifies the circuit layout, but also significantly reduces costs and improves the overall efficiency of the system.
[0020] This utility model effectively drives the AC contactor under low-voltage DC input conditions, avoiding contactor malfunctions caused by grid voltage fluctuations or interruptions. By leveraging the rapid charge and discharge characteristics of high-voltage capacitors, the utility model can promptly provide the instantaneous high current required for contactor closure. Once the contactor is closed, a lower holding current maintains its closed state, effectively extending the contactor's service life.
[0021] In addition, the circuit structure of the present invention is simple, the number of components is small, and it is easy to produce and maintain, which greatly reduces the manufacturing cost and subsequent maintenance expenses. This not only improves the market competitiveness of the product, but also provides users with a more economical and reliable solution. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a schematic structural diagram of the low-voltage DC drive circuit of the utility model;
[0023] Figure 2 Schematic diagram of the first working process of the low-voltage DC drive circuit;
[0024] Figure 3 Schematic diagram of the second working process of the low-voltage DC drive circuit;
[0025] Figure 4 Schematic diagram of the third working process of the low-voltage DC drive circuit. DETAILED DESCRIPTION
[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.
[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.
[0028] Example 1
[0029] This embodiment provides a voltage-adaptive AC contactor low-voltage DC drive circuit, including a low-voltage power supply circuit, a boost circuit and a current limiting circuit connected in sequence; the low-voltage power supply circuit is connected to a low-voltage auxiliary power supply, receives a first DC power input from the low-voltage auxiliary power supply, and outputs the first DC power to the boost circuit; the boost circuit converts the first DC power into a second DC power and outputs the second DC power to the current limiting circuit, and the voltage of the first DC power is lower than the voltage of the second DC power; the current limiting circuit is connected to the AC contactor, and the current limiting circuit is used to store the second DC power, and when the AC contactor is put into operation, the AC contactor is driven by the second DC power and maintains the power supply of the AC contactor.
[0030] In this embodiment, the low-voltage auxiliary power supply can come from the power system, providing DC power input to the circuit. The boost circuit will output a high voltage capable of driving the AC contactor. To ensure the normal operation and operation of the AC contactor, the AC contactor coil requires a stable DC current to maintain its power supply. The current limiting circuit can adaptively reduce the voltage to a level sufficient to maintain the contactor closed, thereby achieving adaptive contactor actuation and maintenance.
[0031] This embodiment only needs to provide one output interface to the AC contactor through the current limiting circuit, and can realize the driving and operation maintenance of the AC contactor without switching circuits, thus having a lower cost and a more simple and effective working mode.
[0032] Example 2
[0033] Based on Example 1, this example introduces in detail a component structure connection method and its working principle for realizing a low-voltage DC drive circuit. Figure 1 As shown, various components in the circuit are shown through multiple PART parts, but they do not correspond to the various circuits described in Example 1. The following is a detailed introduction.
[0034] PART1 includes: low-voltage input bus capacitor C1, primary winding of transformer T1, and switch tube Q1;
[0035] PART2 includes: secondary winding of transformer T1, rectifier diode D1, output bus capacitor C2, current sampling resistor R1;
[0036] PART3 includes: AC contactor coil K1 and output switch S1.
[0037] In combination with the circuit type in Example 1, in this embodiment, the low-voltage power supply circuit includes a low-voltage input bus capacitor C1 and a switch tube Q1; the low-voltage input bus capacitor C1 is used to provide ripple current support for the boost circuit, and the switch tube Q1 is used to provide excitation for the boost circuit through its own controlled breaking mode.
[0038] The boost circuit is implemented using transformer T1. A low-voltage auxiliary power supply (DC) is connected to the transformer T1 primary winding and switch Q1, forming a series circuit. Switch Q1, under controlled conditions, converts the DC power from the low-voltage auxiliary power supply into a pulsed current. This pulsed current, when passing through the transformer's primary winding, generates a varying magnetic field due to electromagnetic induction, inducing a corresponding AC voltage in the transformer's secondary winding, completing the so-called "excitation" process. Input bus capacitor C1 is connected in parallel with the low-voltage auxiliary power supply (DC).
[0039] In this embodiment, the switch tube Q1 is implemented by a MOS tube, and the switching of the MOS tube provides excitation for the primary winding of the transformer T1.
[0040] Likewise Figure 1 As shown, the current limiting circuit includes an output rectifier diode D1, an output bus capacitor C2, and a current sampling resistor R1; the output bus capacitor C2 has a preset voltage threshold, and the secondary winding of the transformer T1 outputs a second DC power through the rectifier diode D1 to charge the output bus capacitor C2 until it reaches the preset voltage threshold; the output bus capacitor C2 is used to provide the current required for the AC contactor to start and close, and the current sampling resistor R1 is used to limit and maintain the current required for the AC contactor to remain closed.
[0041] Rectifier diode D1 converts the AC power induced in the transformer's secondary winding into a second DC power source, charging output bus capacitor C2. The specific connection structure here is: the secondary winding of transformer T1 is sequentially connected to rectifier diode D1, output bus capacitor C2, and current sampling resistor R1 to form a series circuit.
[0042] In this embodiment, the AC contactor's coil K1 is connected in parallel with the output bus capacitor C2, and an output switch S1 is provided in the parallel circuit between the AC contactor's coil K1 and the output bus capacitor C2. To successfully achieve current limiting and adaptive maintenance after the AC contactor is closed, the load current of the AC contactor's coil K1 is greater than the output current of the transformer T1 limited by the current sampling resistor R1.
[0043] Based on the structural connection relationship provided in this embodiment, the following is an introduction to the working principle of the circuit of this embodiment.
[0044] The first working process is as follows Figure 2 As shown in the figure: when the output switch S1 is disconnected, the coil K1 load of the AC contactor is not connected to the circuit; the low-voltage DC+ and low-voltage DC- provided by the low-voltage auxiliary power supply DC input the first DC power, and through the control of the switch tube Q1, the primary winding of the transformer T1 is excited; in this process, the input bus capacitor C1 provides ripple current support for the primary winding, and the secondary winding of the transformer T1 charges the output bus capacitor C2 through the rectifier diode D1 until the voltage of the output bus capacitor C2 reaches its preset voltage threshold.
[0045] The second working process is as follows Figure 3 As shown in the figure: at the moment when the output switch S1 is closed, which also corresponds to the moment when the coil K1 of the AC contactor is connected, since the DC impedance of the coil K1 is very low, the relatively high high-voltage electric energy from the output bus capacitor C2 will form a transient large current on the coil K1. This current can generate a transient strong magnetic field on the coil K1, so that the AC contactor has sufficient suction force to close, completing the closing action of the AC contactor.
[0046] The third working process is as follows Figure 4As shown in the figure: after the output switch S1 is closed, the AC contactor also completes the closing action accordingly. Since the output current of the transformer T1 has been limited by the current sampling resistor R1, the load current of the coil K1 of the AC contactor will be greater than the output current of the transformer T1. At this time, the transformer T1 cannot maintain the charging of the output bus capacitor C2, that is, the voltage of the output bus capacitor C2 cannot reach its preset voltage threshold; the voltage of the output bus capacitor C2 therefore continues to decrease until the current flowing through the coil K1 of the AC contactor is stabilized and equal to the output current of the transformer T1. This current can continuously keep the coil K1 of the AC contactor closed, and the entire closing process of the AC contactor is completed and stably maintained.
Claims
1. A voltage-adaptive AC contactor low-voltage DC drive circuit, characterized in that: It includes a low-voltage power supply circuit, a boost circuit and a current limiting circuit connected in sequence; the low-voltage power supply circuit is connected to a low-voltage auxiliary power supply, receives a first DC power input from the low-voltage auxiliary power supply, and outputs the first DC power to the boost circuit; the boost circuit converts the first DC power into a second DC power and outputs it to the current limiting circuit, and the voltage of the first DC power is lower than the voltage of the second DC power; the current limiting circuit is connected to an AC contactor, and the current limiting circuit is used to store the second DC power, and when the AC contactor is put into operation, the AC contactor is driven by the second DC power and maintains the power supply of the AC contactor.
2. The low-voltage DC drive circuit according to claim 1, wherein: The low-voltage power supply circuit includes a low-voltage input bus capacitor C1 and a switch tube Q1; the low-voltage input bus capacitor C1 is used to provide ripple current support for the boost circuit, and the switch tube Q1 is used to provide excitation for the boost circuit through its own controlled breaking mode.
3. The low-voltage DC drive circuit according to claim 2, wherein: The boost circuit is implemented using transformer T1; the low-voltage auxiliary power supply DC is sequentially connected to the primary winding of transformer T1 and the switch tube Q1 to form a series loop.
4. The low-voltage DC drive circuit according to claim 3, wherein: The input bus capacitor C1 is connected in parallel with the low voltage auxiliary power supply DC.
5. The low-voltage DC drive circuit according to claim 3, wherein: The switch tube Q1 is implemented by a MOS tube, and the opening and closing of the MOS tube provides excitation for the primary winding of the transformer T1.
6. The low-voltage DC drive circuit according to claim 3, wherein: The current limiting circuit includes an output rectifier diode D1, an output bus capacitor C2, and a current sampling resistor R1. The output bus capacitor C2 has a preset voltage threshold. The secondary winding of the transformer T1 outputs a second DC power through the rectifier diode D1 to charge the output bus capacitor C2 until it reaches the preset voltage threshold. The output bus capacitor C2 is used to provide the current required for the AC contactor to start and close. The current sampling resistor R1 is used to limit and maintain the current required to keep the AC contactor closed.
7. The low-voltage DC drive circuit according to claim 6, wherein: The secondary winding of the transformer T1 is connected in sequence to the rectifier diode D1, the output bus capacitor C2 and the current sampling resistor R1 to form a series loop.
8. The low-voltage DC drive circuit according to claim 7, wherein: The coil K1 of the AC contactor is connected in parallel with the output bus capacitor C2.
9. The low-voltage DC drive circuit according to claim 8, characterized in that: An output switch S1 is also provided in the parallel circuit of the coil K1 of the AC contactor and the output bus capacitor C2.
10. The low-voltage DC drive circuit according to claim 8, wherein: The load current of the coil K1 of the AC contactor is greater than the output current of the transformer T1 limited by the current sampling resistor R1.