An ac contactor driver

Abstract

The application relates to an alternating current (AC) contactor driver and relates to the technical field of AC contactor driving; the AC contactor driver comprises an AC-DC rectification unit, a signal processing unit and a DC-AC driving unit, an input end of the AC-DC rectification unit is electrically connected to an external AC control signal, output ends of the AC-DC rectification unit are respectively electrically connected to a power supply end of the signal processing unit and the DC-AC driving unit; an input end of the signal processing unit is electrically connected to an output end of the AC-DC rectification unit, and an output end of the signal processing unit is electrically connected to a control end of the DC-AC driving unit; an output end of the DC-AC driving unit is electrically connected to a control end of an AC contactor; an energy storage capacitor C1 is arranged in the AC-DC rectification unit, a positive pole of the energy storage capacitor C1 is electrically connected to an output end of the AC-DC rectification unit, and a negative pole of the energy storage capacitor C1 is grounded. The application has the effects of avoiding the failure of an AC contactor driving circuit as much as possible during voltage fluctuation and improving the anti-interference capability.

Description

Technical Field

[0001] This application relates to the technical field of AC contactor drives, and more particularly to an AC contactor driver. Background Technology

[0002] In the fields of industrial automation and power control, AC contactors, as an important control element, are widely used in the start-up, shutdown, and switching control of various power equipment. With the continuous development of power systems and the increasing demand for intelligent systems, higher requirements are placed on the performance and stability of AC contactor drive circuits. A reliable and efficient drive circuit not only ensures the normal operation of the AC contactor but also improves the overall operating efficiency and reliability of the power system, reduces the probability of failure, and lowers maintenance costs. At the same time, a good drive circuit also helps to realize remote control and intelligent management of power equipment, meeting the diverse needs of modern industrial production.

[0003] Traditionally, the common practice for AC contactor drive circuits is to use a simple rectifier circuit to convert the external AC control signal into a DC signal and then directly drive the AC contactor. This method can achieve basic control functions to a certain extent. Some circuits use transformers for voltage conversion and isolation, along with appropriate amplifier circuits to drive the AC contactor. Additionally, some circuits employ analog signal processing units to adjust the signal amplitude and frequency to suit the operating requirements of the AC contactor. These methods have been widely used for some time, providing feasible solutions for driving AC contactors.

[0004] However, when encountering a momentary drop in the external AC control signal voltage, such as when the power grid fluctuates or is interfered with, the rectifier output may drop temporarily due to the lack of effective countermeasures. This can easily cause the system to restart or fail due to short-term voltage deficiency, making it impossible to guarantee the stable power supply of the circuit. Consequently, it affects the normal operation of the AC contactor and the reliability of the entire power system. Utility Model Content

[0005] To address the problems of traditional AC contactor drive circuits being prone to failure under voltage fluctuations and having poor anti-interference capabilities, this application provides an AC contactor driver.

[0006] The AC contactor driver provided in this application adopts the following technical solution:

[0007] An AC contactor driver includes an AC-DC rectifier unit, a signal processing unit, and a DC-AC drive unit. The first input terminal of the AC-DC rectifier unit is electrically connected to the L terminal of an external AC control signal, and the second input terminal is electrically connected to the N terminal of the external AC control signal. The output terminal of the AC-DC rectifier unit is electrically connected to the power supply terminals of the signal processing unit and the DC-AC drive unit, respectively. The input terminal of the signal processing unit is electrically connected to the output terminal of the AC-DC rectifier unit, and the output terminal of the signal processing unit is electrically connected to the control terminal of the DC-AC drive unit. The output terminal of the DC-AC drive unit is electrically connected to the control terminal of an AC contactor. An energy storage capacitor C1 is disposed within the AC-DC rectifier unit, with the positive terminal of the energy storage capacitor C1 electrically connected to the output terminal of the AC-DC rectifier unit, and the negative terminal of the energy storage capacitor C1 grounded.

[0008] By adopting the above technical solution, the AC-DC rectifier unit converts the external AC control signal into a stable DC signal to power the signal processing unit and the DC-AC drive unit. The signal processing unit outputs a signal to control the DC-AC drive unit, and the DC-AC drive unit outputs an adapted drive signal to control the AC contactor. When the voltage of the external AC control signal drops momentarily, the energy storage capacitor C1 releases the stored energy to temporarily maintain the power supply of the circuit, preventing the system from restarting or failing due to short-term voltage deficiency, and improving the anti-interference capability.

[0009] Preferably, the AC-DC rectifier unit includes a rectifier and a step-down module connected in series. The first input terminal of the rectifier is electrically connected to the L terminal of the external AC control signal, the second input terminal is electrically connected to the N terminal of the external AC control signal, the output terminal of the rectifier is electrically connected to the input terminal of the step-down module, and the output terminal of the step-down module is set as the output terminal of the AC-DC rectifier unit.

[0010] By adopting the above technical solution, the AC contactor drive circuit can use a rectifier to convert the external AC control signal into a DC signal, and then adjust the voltage through a step-down module, thereby providing a suitable operating voltage for subsequent units.

[0011] Preferably, the signal processing unit includes an operational amplifier and an AC signal controller. The non-inverting input terminal of the operational amplifier is electrically connected to the L terminal of the external AC control signal, the inverting input terminal of the operational amplifier is grounded, the output terminal of the operational amplifier is electrically connected to the input terminal of the AC signal controller, and the output terminal of the AC signal controller is electrically connected to the control terminal of the DC-AC drive unit.

[0012] By adopting the above technical solution, the signal processing unit can amplify the input signal by adjusting the amplitude of the external AC control signal through an operational amplifier. Then, through the AC signal controller, filtering and shaping are performed to generate an AC signal with the same frequency and phase as the input, namely the SPWM signal.

[0013] Preferably, the DC-AC drive unit includes a full-bridge module, and the full-bridge module includes multiple MOS transistors; the control terminals of the multiple MOS transistors are electrically connected to the output terminal of the signal processing unit, and the midpoint of the bridge arm of the full-bridge module is electrically connected to the control terminal of the AC contactor.

[0014] By adopting the above technical solution, the output signal of the signal processing unit controls the switching and frequency of multiple MOS transistors, generating a drive signal adapted to the AC contactor, thereby achieving precise control.

[0015] Preferably, the system further includes an isolation unit and a control unit. The first input terminal of the isolation unit is electrically connected to terminal A of the external communication interface, the second input terminal is electrically connected to terminal B of the external communication interface, the output terminal of the isolation unit is electrically connected to the input terminal of the control unit, and the output terminal of the control unit is electrically connected to the control terminal of the signal processing unit.

[0016] By adopting the above technical solution, electrical isolation between external communication signals (such as RS485) and internal circuits is achieved, improving anti-interference capability and safety; the control unit is used to receive the output signal of the isolation unit and output the corresponding control signal to the signal processing unit according to the output signal, so that the signal processing module can generate an SPWM signal that meets the requirements.

[0017] Preferably, the isolation unit includes a current transformer for converting RS485 signals into UART signals.

[0018] By adopting the above technical solution, the current transformer can convert RS485 signals into UART signals, while isolating high voltage interference and protecting the internal circuit.

[0019] Preferably, the control unit includes a protocol parsing module for verifying the legality of communication signals and executing control commands.

[0020] By employing the above technical solution, the protocol parsing module verifies the legitimacy of communication signals, preventing illegal commands or interference signals from affecting the system. If the signals are legitimate, the control module controls the signal processing module to execute the parsed commands, ensuring the accuracy and security of the control logic.

[0021] Preferably, the system also includes an LDO low-voltage regulator, and the output of the AC-DC rectifier unit is electrically connected to the power supply terminals of the signal processing unit, the isolation unit, and the control unit through the LDO low-voltage regulator.

[0022] By adopting the above technical solution, a stable, low-noise operating voltage is provided for the signal processing unit, isolation unit, and control unit.

[0023] In summary, this application includes at least one of the following beneficial technical effects:

[0024] 1. The energy storage capacitor C1 in the AC-DC rectifier unit can release the stored electrical energy when the external AC control signal voltage drops momentarily, temporarily maintaining the power supply to the circuit, preventing the system from restarting or failing due to short-term voltage deficiency, and improving anti-interference capability;

[0025] 2. The signal processing unit adjusts the amplitude of the external AC control signal through an operational amplifier and generates an SPWM signal with the same frequency and phase as the external AC control signal through an AC signal controller, so that the circuit can generate an AC signal that is compatible with the AC contactor.

[0026] 3. By employing isolation units and control units, electrical isolation of external RS485 signals and verification of command validity are achieved, which not only enhances anti-interference capabilities but also prevents the intrusion of illegal control commands, making it suitable for harsh communication environments such as industrial automation. Attached Figure Description

[0027] Figure 1 This is a circuit diagram of Embodiment 1 of this application;

[0028] Figure 2 This is a circuit diagram of Embodiment 2 of this application. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail. Example

[0030] Embodiment 1 of this application discloses an AC contactor driver.

[0031] Reference Figure 1An AC contactor driver includes an AC-DC rectifier unit, a signal processing unit, and a DC-AC drive unit. The L terminal of an external AC control signal is electrically connected to a first input terminal of the AC-DC rectifier unit, and the N terminal of the external AC control signal is electrically connected to a second input terminal of the AC-DC rectifier unit. The output terminal of the AC-DC rectifier unit is electrically connected to the power supply terminals of the signal processing unit and the DC-AC drive unit. The L terminal of the external AC control signal is electrically connected to the signal processing unit, and the output terminal of the signal processing unit is electrically connected to the output terminal of the DC-AC drive unit. The signal processing unit is used to output an SPWM signal. The output terminal of the DC-AC drive unit is electrically connected to the control terminal of the AC contactor. This connection allows the circuit to convert the external AC control signal into a drive signal suitable for the AC contactor.

[0032] The AC-DC rectifier unit includes a rectifier, a step-down module, and an energy storage capacitor C1. The L terminal of the external AC control signal is electrically connected to the first input terminal of the rectifier, and the N terminal is electrically connected to the second input terminal of the rectifier. The ground terminal of the rectifier is grounded, and the output terminal of the rectifier is used to output a DC signal. The output terminal of the rectifier is electrically connected to the input terminal of the step-down module, and the output terminal of the step-down module is set as the output terminal of the rectifier unit. The step-down module is used to reduce the rectified DC voltage to a suitable value for use by subsequent units. The positive terminal of the energy storage capacitor C1 is electrically connected to the output terminal of the rectifier, and the negative terminal of the energy storage capacitor C1 is grounded. The energy storage capacitor C1 can temporarily store electrical energy. When the voltage of the external AC control signal drops momentarily (such as due to grid fluctuations or interference), the rectifier output may drop briefly. At this time, the energy storage capacitor C1 releases the stored electrical energy to temporarily maintain the power supply to the circuit, preventing the system from restarting or failing due to short-term voltage deficiency, and improving the anti-interference capability.

[0033] The DC-AC drive unit includes a full-bridge module, which comprises multiple MOSFETs. The control terminals of the multiple MOSFETs are electrically connected to the output terminal of the signal processing unit, and the midpoint of the bridge arm of the full-bridge module is electrically connected to the control terminal of the AC contactor. By controlling the SPWM signal output by the signal processing unit, the switching and frequency of the multiple MOSFETs are controlled, thereby generating an AC signal that can adapt to the AC contactor.

[0034] The signal processing unit includes an operational amplifier (op-amp) and an AC signal controller. The L terminal of the external AC control signal is electrically connected to the non-inverting input terminal of the op-amp, the inverting input terminal of the op-amp is grounded, and the output terminal of the op-amp is electrically connected to the input terminal of the AC signal controller. The output terminal of the AC signal controller is electrically connected to the control terminal of the DC-AC drive unit. The op-amp amplifies the input signal, and the AC signal controller performs filtering and shaping to generate an AC signal with the same frequency and phase as the input.

[0035] The implementation principle of an AC contactor driver according to Embodiment 1 of this application is as follows: The AC contactor driver circuit first converts the external AC control signal into a stable DC signal through an AC-DC rectifier unit. The energy storage capacitor provides temporary power during voltage dips, ensuring power supply stability. The signal processing unit uses an operational amplifier to adjust the amplitude of the input signal, and then generates a synchronous SPWM control signal through an AC signal controller. The DC-AC drive unit adopts a full-bridge MOSFET structure to convert the SPWM signal into a drive signal adapted to the AC contactor. This design gives the circuit a wide voltage adaptability range and fast dynamic response capability. It integrates voltage dip protection, effectively preventing the system from restarting or failing due to short-term voltage shortage. It is particularly suitable for intelligent power distribution systems, achieving high efficiency and energy saving, reducing standby power consumption, and also possessing a certain degree of stability and reliability, representing a significant improvement over traditional drive circuits. Example

[0036] Embodiment 3 of this application discloses another AC contactor driver.

[0037] refer to Figure 2 This embodiment 2 is similar in structure to embodiment 1, except that it further includes an isolation unit and a control unit. The A terminal of the external communication interface is electrically connected to the first input terminal of the isolation unit, the B terminal of the external communication interface is electrically connected to the second output terminal of the isolation unit, and the output terminal of the isolation unit is electrically connected to the input terminal of the control unit. The output terminal of the control unit is electrically connected to the control terminal of the signal unit, thereby enabling control of the SPWM signal output.

[0038] The isolation unit includes a current transformer. Terminal A is electrically connected to one end of the primary side of the current transformer, and terminal B is electrically connected to the other end of the primary side of the current transformer. The current transformer can electrically isolate external input signals, induce the RS485 signal on the primary side to the secondary side and convert it into a TTL level UART serial port signal, thereby improving the security and anti-interference capability of signal transmission.

[0039] The control unit includes a protocol parsing module. The input of the protocol parsing module is electrically connected to the output of the isolation unit, used to receive UART serial port signals and execute corresponding control commands. The output of the protocol parsing module is electrically connected to the control terminal of the signal processing unit. The protocol parsing module is used to parse the UART serial port signals and determine whether the signal is valid. If valid, the control unit executes the control commands in the protocol and sends the control commands to the signal processing module, enabling the signal processing module to output an SPWM signal.

[0040] This embodiment also includes an LDO low-voltage regulator. The output of the AD-DC rectifier unit is electrically connected to the power supply terminals of the signal processing unit, isolation unit, and control unit via the LDO low-voltage regulator. The LDO low-voltage regulator can stabilize the voltage output of the AC-DC rectifier unit to a suitable value, providing a stable power supply for subsequent units.

[0041] The implementation principle of an AC contactor driver in Embodiment 2 of this application is as follows: By adding an isolation unit and a control unit based on Embodiment 1, electrical isolation and protocol-based control of the RS485 signal are achieved. The external RS485 signal is isolated by a current transformer and converted to UART TTL level. After protocol parsing and instruction verification by the control unit, the signal processing unit generates an SPWM waveform, which is finally controlled by a power device to operate the AC contactor. This design significantly improves the system's anti-interference capability, communication security, and control flexibility through triple protection of signal isolation, protocol filtering, and SPWM modulation.

[0042] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An AC contactor driver, characterized in that: The system includes an AC-DC rectifier unit, a signal processing unit, and a DC-AC drive unit. The first input terminal of the AC-DC rectifier unit is electrically connected to the L terminal of an external AC control signal, and the second input terminal is electrically connected to the N terminal of the external AC control signal. The output terminal of the AC-DC rectifier unit is electrically connected to the power supply terminals of the signal processing unit and the DC-AC drive unit, respectively. The input terminal of the signal processing unit is electrically connected to the output terminal of the AC-DC rectifier unit, and the output terminal of the signal processing unit is electrically connected to the control terminal of the DC-AC drive unit. The output terminal of the DC-AC drive unit is electrically connected to the control terminal of an AC contactor. An energy storage capacitor C1 is provided within the AC-DC rectifier unit. The positive terminal of the energy storage capacitor C1 is electrically connected to the output terminal of the AC-DC rectifier unit, and the negative terminal of the energy storage capacitor C1 is grounded.

2. The AC contactor driver according to claim 1, characterized in that: The AC-DC rectifier unit includes a rectifier and a step-down module connected in series. The first input terminal of the rectifier is electrically connected to the L terminal of the external AC control signal, and the second input terminal is electrically connected to the N terminal of the external AC control signal. The output terminal of the rectifier is electrically connected to the input terminal of the step-down module, and the output terminal of the step-down module is set as the output terminal of the AC-DC rectifier unit.

3. An AC contactor driver according to claim 1, characterized in that: The signal processing unit includes an operational amplifier and an AC signal controller. The non-inverting input terminal of the operational amplifier is electrically connected to the L terminal of the external AC control signal, the inverting input terminal of the operational amplifier is grounded, the output terminal of the operational amplifier is electrically connected to the input terminal of the AC signal controller, and the output terminal of the AC signal controller is electrically connected to the control terminal of the DC-AC drive unit.

4. An AC contactor driver according to claim 1, characterized in that: The DC-AC drive unit includes a full-bridge module, and the full-bridge module includes multiple MOS transistors; the control terminals of the multiple MOS transistors are electrically connected to the output terminal of the signal processing unit, and the midpoint of the bridge arm of the full-bridge module is electrically connected to the control terminal of the AC contactor.

5. An AC contactor driver according to claim 1, characterized in that: It also includes an isolation unit and a control unit. The first input terminal of the isolation unit is electrically connected to terminal A of the external communication interface, the second input terminal is electrically connected to terminal B of the external communication interface, the output terminal of the isolation unit is electrically connected to the input terminal of the control unit, and the output terminal of the control unit is electrically connected to the control terminal of the signal processing unit.

6. An AC contactor driver according to claim 5, characterized in that: The isolation unit includes a current transformer for converting RS485 signals into UART signals.

7. An AC contactor driver according to claim 5, characterized in that: The control unit includes a protocol parsing module, which is used to verify the legality of communication signals and execute control commands.

8. An AC contactor driver according to claim 5, characterized in that: It also includes an LDO low-voltage regulator, and the output terminal of the AC-DC rectifier unit is electrically connected to the power supply terminal of the signal processing unit, the isolation unit and the control unit through the LDO low-voltage regulator.

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