An ac-dc contactor control circuit and contactor

Abstract

The application relates to an AC-DC contactor control circuit and a contactor, and relates to the field of contactor control. The AC-DC contactor control circuit comprises an AC-DC power supply module, a voltage detection module, an excitation control module, a closing and maintaining module and a driving output module. The AC-DC power supply module is connected with an external driving power supply through an external driving power supply interface. The voltage detection module is connected with the external driving power supply interface, the excitation control module and the closing and maintaining module, can form different trigger signals to control the working states of the excitation control module and the closing and maintaining module, the excitation control module is connected with the closing and maintaining module and the driving output module, can control the driving output module to generate an excitation driving current for driving the contactor to close, and can control the driving output module to generate a closing and maintaining current for maintaining the closing state of the contactor through the closing and maintaining module, so that the real-time performance of the contactor control can be improved, and the operation power consumption of the contactor can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of contactor control, in particular to an AC / DC contactor control circuit. In addition, the present application also discloses an AC / DC contactor. BACKGROUND

[0002] A contactor is a kind of switch appliance that uses electromagnetic, pneumatic or hydraulic principle to realize the on-off of the main circuit through a control circuit, and has the advantages of strong current load capacity, rapid action, safe operation, frequent operation and remote control. The main control object of the contactor is a motor, and it can also be used to control other large current power loads such as welding machines and furnaces.

[0003] An electromagnetic contactor is the most widely used contactor at present, and its working principle is that a control current is input into the coil of the contactor, and after the coil is powered on, a magnetic force is generated on the iron core to attract the armature, which drives the movable contact fixed on the armature to contact the static contact to turn on the main circuit. As a switching device for controlling various different power loads, the contactor needs to be applied in AC / DC working circuits of various different working voltages, and in order to meet the requirements of high reliability control occasions for the stability of the control system, higher requirements are also put forward for the closing time and opening time of the contactor. In order to reduce the closing time of the contactor, it is usually necessary to increase the control current of the contactor coil, and the contactor usually needs to be kept in the closed state for a long time during the working time, which will increase the power consumption of the contactor coil during the closing stage and easily cause the aging and damage of the coil. In order to reduce the opening time of the contactor, the control current of the contactor coil needs to be quickly reduced.

[0004] In order to reduce the closing time of the contactor while reducing the power consumption of the coil in the closed state, a kind of PWM control signal formed by controller programming has appeared in the prior art, which is used to control the current of the contactor coil, uses a large excitation current to promote the rapid closing of the contactor, and uses a smaller maintenance current to ensure the closed state of the contactor after closing, thereby reducing the energy consumption of the coil in the closed state. However, the control circuit needs to use the corresponding driving circuit of the microcontroller chip to realize it, and the circuit design and use cost are high, and the running of the software program needs a certain execution time, which affects the real-time performance of the contactor action. SUMMARY

[0005] In order to improve the real-time performance of the contactor control and reduce the running power consumption of the contactor, the present application provides an AC / DC contactor control circuit.

[0006] The AC / DC contactor control circuit provided by the present application adopts the following technical scheme:

[0007] The application discloses an AC-DC contactor control circuit which comprises an AC-DC power module, a voltage detection module, an excitation control module, a closing maintenance module and a driving output module, wherein the AC-DC power module comprises an external driving power source interface, can be connected with an external driving power source through the external driving power source interface, converts the external driving power source into a DC power source for driving the control circuit to work, the voltage detection module is connected with the external driving power source interface, the excitation control module and the closing maintenance module, can detect the AC-DC state of the external driving power source, forms different trigger signals to trigger the excitation control module, the excitation control module is connected with the closing maintenance module and the driving output module, can generate excitation control signals to control the driving output module to generate an excitation driving current for driving the contactor to close, and controls the working state of the closing maintenance module, the closing maintenance module is connected with the driving output module, can generate maintenance control signals to control the driving output module to generate a constant closing maintaining current for maintaining the closing state of the contactor, and the driving output module is connected with a contactor coil, can output the driving current to the contactor coil.

[0008] By adopting the technical scheme, the AC-DC power source for driving the contactor coil to act is converted into a DC power source by the AC-DC power module, the DC power source is used to drive the control circuit to work and the contactor coil to generate an electromagnetic force, so that the contactor circuit can be used in different AC-DC circuits, and the applicability of the contactor circuit is improved; the voltage detection module is used to detect the AC-DC state of the external driving power source, so that excitation trigger signals and maintenance trigger signals can be generated at different times according to the AC-DC state of the external driving power source, and the reliable action of the contactor in different AC-DC circuits is ensured; the excitation control module and the closing maintenance module are used to generate a large excitation driving current in the closing stage of the contactor by the excitation control module, reduce the closing time of the contactor, generate a small constant current closing maintaining current in the closing state of the contactor by the maintenance trigger signal, reduce the power consumption of the contactor coil and prolong the service life of the contactor.

[0009] In one specific embodiment, the AC / DC power module comprises an EMI protection unit, a rectification unit, a contactor coil power supply unit, a fast establishment power supply unit, a working power supply unit, a DC output unit and a reference voltage unit, the EMI protection unit is connected with the external driving power supply interface, the rectification unit is connected with the EMI protection unit, the contactor coil power supply unit, the fast establishment power supply unit and the working power supply unit are connected at the output end of the rectification unit respectively, the contactor coil power supply unit can output power for driving the contactor to work, the fast establishment power supply unit can form DC power required for the working of the control circuit in advance, the working power supply unit can form stabilized DC power replacing the fast establishment power supply unit, the DC output unit is connected with the fast establishment power supply unit and the working power supply unit respectively to output the DC power formed by the fast establishment power supply unit and the working power supply unit, and the reference voltage unit is connected with the DC output unit to output reference voltage of a set size.

[0010] By using the above technical scheme, the fast establishment power supply unit can quickly establish DC power for driving the control circuit to work by using the external driving power supply, so that the control circuit can quickly enter the working state and the closing time of the contactor is reduced; the working power supply unit can form stabilized constant-voltage DC power, ensuring the stability of the working of the control circuit, so that the closing holding current of the contactor coil in the closed state of the contactor can be accurately controlled, and the closing holding current and the power consumption of the contactor coil are reduced while ensuring that the contactor is in a reliable closed state.

[0011] In one specific embodiment, the contactor coil power supply unit comprises a power supply protection subunit, an output control subunit and a fuse device, the power supply protection subunit is connected between the rectification unit and the output control subunit to provide overvoltage and overcurrent protection for the output control subunit, the output control subunit is connected with the working power supply unit and the driving output module to control the working state of the output control subunit according to the signals of the working power supply unit and the driving output module, and the fuse device is connected on the output loop of the output control subunit; the AC / DC power module further comprises a fast discharge unit, the fast discharge unit is connected with the rectification unit, the fast discharge unit comprises a fast discharge loop and can output fast discharge power connected with the fast discharge loop.

[0012] By adopting the technical scheme, the power supply protection subunit, the output control subunit and the fuse device can form triple overcurrent protection for the PTC resistance, the control circuit and the fuse device of the contactor coil, and better ensure the safety of the contactor coil during operation; the rapid discharge unit arranged in the AC / DC power module can quickly release the energy contained in the components within the power supply range after the power supply of the control circuit is interrupted, so as to ensure that the control circuit quickly enters the power-off state and accelerate the opening speed of the contactor.

[0013] In one specific implementation, the voltage detection module includes an AC signal extraction unit and an under-voltage protection unit. The AC signal extraction unit is connected to the external driving power supply interface to detect whether the external driving power supply is an AC power supply. The under-voltage protection unit is connected to the AC signal extraction unit, the AC / DC power module and the excitation control module to output control signals according to different AC / DC states and voltage values of the external driving power supply, and control the working state of the excitation control module.

[0014] By adopting the technical scheme, the AC signal extraction unit can extract the AC signal in the external driving power supply to determine the AC / DC state of the external driving power supply and control the under-voltage protection unit to form different under-voltage protection thresholds. The under-voltage protection unit can determine the voltage state of the external driving power supply in combination with the output signal of the AC signal extraction unit, control the contactor to be disconnected when the external driving power supply is under-voltage, and prevent the power load from being damaged due to failure to work normally under the under-voltage state.

[0015] In one specific implementation, the voltage detection module further includes an over-voltage protection unit connected to the AC signal extraction unit, the reference voltage unit and the closing maintenance module to control the closing maintenance module to act and cut off the output of the driving output module when the voltage of the external driving power supply exceeds the set range.

[0016] By adopting the technical scheme, the over-voltage protection unit connected to the AC signal extraction unit, the reference voltage unit and the closing maintenance module can determine the voltage state of the external driving power supply in combination with the output signal of the AC signal extraction unit, form an over-voltage control signal when the voltage of the external driving power supply exceeds the set voltage value by a set range, control the contactor to be disconnected through the closing maintenance module, and prevent the contactor coil or the power load from being damaged due to excessively high voltage of the external driving power supply.

[0017] In one specific implementation, the excitation control module includes an excitation pulse forming unit, an excitation drive unit and a hold mode control unit, the excitation pulse forming unit is connected with the voltage detection module to generate an excitation trigger pulse with a set width according to the state of the external driving power supply, the excitation drive unit is connected between the excitation pulse forming unit and the drive output module to generate an excitation control signal corresponding to the excitation trigger pulse to control the drive output module to generate an excitation drive current, and the hold mode control unit is connected between the excitation pulse forming unit and the closing maintenance module and the drive output module to control the working state of the closing maintenance module and the drive output module after the excitation trigger pulse ends.

[0018] By using the above technical solution, the excitation pulse forming unit connected with the voltage detection module can generate an excitation trigger pulse with a set width under the normal power supply state of the external driving power supply, the excitation drive unit can generate an excitation control signal within a set time, and the drive output module can generate a large current excitation drive current in the contactor coil to drive the contactor to quickly attract and reduce the closing time of the contactor. The hold mode control unit connected between the excitation pulse forming unit and the closing maintenance module and the drive output module can form two different working modes of the magnetic hold mode and the mechanical hold mode of the AC / DC contactor control circuit in the closing maintenance stage, so that the AC / DC contactor control circuit can be used in the magnetic hold contactor and the mechanical hold contactor respectively, and the application range of the AC / DC contactor control circuit is improved.

[0019] In one specific implementation, the closing maintenance module includes a PWM control unit, a PWM suppression unit and a feedback adjustment unit, the PWM control unit is connected with the PWM suppression unit, the feedback adjustment unit and the drive output module to generate a PWM control signal under the control of the PWM suppression unit and the feedback adjustment unit to control the size of the drive current generated by the drive output module, the PWM suppression unit is connected with the hold mode control unit, the voltage detection module and the PWM control unit to control the working state of the PWM control unit according to the excitation mode of the contactor and the voltage state of the external driving power supply, and the feedback adjustment unit is connected with the drive output module, the excitation pulse forming unit and the PWM control unit to control the working state of the PWM control unit according to the excitation trigger pulse and the drive current output by the drive output module, so as to control the size of the drive current generated by the drive output module.

[0020] By adopting the technical scheme, the PWM control unit connected with the drive output module can control the duty cycle of the generated PWM drive signal according to the size of the drive current generated by the drive output module, and control the size of the drive output by the drive output module using the adjusted PWM drive signal, so as to stably control the closing and holding current in the closing and holding stage of the contactor coil to a smaller level; the PWM suppression unit connected between the holding mode control unit, the voltage detection module and the PWM control unit can control the PWM control unit to stop outputting the PWM drive signal in the excitation stage and the closing and holding stage of the mechanical holding mode, so as to ensure that the excitation drive current can reach a larger value and reduce unnecessary energy consumption; the feedback adjustment unit arranged between the drive output module 5 and the excitation pulse forming unit 31 and the PWM control unit can generate a feedback adjustment signal when the drive current output by the drive output module 5 is too large, control the duty cycle of the PWM drive signal, and thereby limit the size of the excitation drive current within the set maximum value range.

[0021] In a specific implementation scheme, the drive output module includes a coil drive unit, a coil voltage feedback unit, a coil current monitoring unit, an excitation current limiting unit and a drive tube short circuit protection unit, the coil drive unit is connected with the excitation control module, the closing and holding module and the contactor coil, so as to output drive current to the contactor coil under the control of the excitation control signal and the holding control signal, the coil voltage feedback unit and the coil current monitoring unit are connected on the power supply circuit of the contactor coil and connected with the closing and holding module, so as to generate feedback signals corresponding to the power supply voltage and power supply current of the contactor coil, and adjust the working state of the closing and holding module, the excitation current limiting unit is connected with the coil drive unit and the excitation control module, so as to control the working state of the excitation control module when the output current of the coil drive unit reaches the first set value, and control the maximum value of the output current of the coil drive unit, the drive tube short circuit protection unit is connected with the coil current monitoring unit and the AC / DC power supply module, so as to control the AC / DC power supply module to act when the power supply current of the contactor coil is greater than the second set value, and cut off the power supply of the contactor coil.

[0022] By adopting the technical scheme, the coil driving unit arranged between the excitation control module, the closing maintaining module and the contactor coil can form an excitation driving current for driving the contactor to attract and a closing maintaining current for maintaining the closing state of the contactor by controlling the different driving currents of the excitation control signal and the control output of the PWM driving signal generated by the closing maintaining module; the coil voltage feedback unit and the coil current monitoring unit arranged on the power supply circuit of the contactor coil can monitor the current and voltage of the contactor coil in real time, and adjust the duty cycle of the PWM driving signal output by the closing maintaining module according to the monitoring result, so as to ensure the stability of the driving current output by the coil driving unit; the excitation current limiting unit can switch the coil driving unit to the PWM working mode when the excitation current is too large, so as to limit the maximum value of the excitation current; and the driving tube short-circuit protection unit can cut off the power supply of the contactor coil power supply unit when the driving tube of the coil driving unit is broken and the current of the contactor coil is uncontrollably increased, so as to prevent the contactor coil from being burned in a long-time and large-current state.

[0023] In a specific implementation, the driving output module further comprises a quick turn-off unit connected between the voltage detection module and the contactor coil, so as to generate a demagnetizing voltage when the voltage of the external driving power supply is lower than a set value, thereby improving the decay speed of the current in the contactor coil.

[0024] By adopting the technical scheme, the quick turn-off unit arranged between the voltage detection module and the contactor coil can generate a demagnetizing voltage when the voltage of the external driving power supply is lower than a set value and the under-voltage protection unit in the voltage detection module is started, so as to resist the induced electromotive force generated by the contactor coil due to power loss, accelerate the decay speed of the current in the contactor coil, and shorten the opening time of the contactor.

[0025] The AC / DC contactor of the application uses the AC / DC contactor control circuit provided by the application, and also has the above advantages.

[0026] In summary, the application has at least one of the following beneficial technical effects:

[0027] 1. By arranging the excitation control module and the closing maintaining module, the excitation control module can generate an excitation control signal with a set duration, the driving output module can generate a short-time and large-current excitation driving current in the contactor coil to drive the contactor to attract and shorten the closing time of the contactor, and the closing maintaining module can generate a maintaining control signal after the contactor is in the closing state to control the driving output module to generate a constant attracting maintaining current with a small current in the contactor coil, so as to maintain the closing state of the contactor with a small driving current, reduce the power consumption of the contactor in the closing state, and prolong the service life of the contactor.

[0028] 2. By setting the AC / DC power supply module, the AC / DC power supply provided by the external driving power supply can be converted into a DC power supply for driving the control circuit and the contactor coil to work, and the supply of the large load DC power supply can be quickly established by quickly establishing the power supply unit, so that the large current excitation driving current can be quickly formed, the closing time of the contactor is reduced, and after the contactor is in the closing state, the working power supply unit is converted to provide a small load steady DC power supply, the small current and constant attraction holding current is improved, and the contactor is stably maintained in the closing state under the driving of the small current.

[0029] 3. By setting the AC signal extraction unit, the under-voltage protection unit and the over-voltage protection unit, different under-voltage protection thresholds and different over-voltage protection thresholds can be formed according to the AC / DC state of the external driving power supply, so that the contactor can have different under-voltage protection thresholds and over-voltage protection thresholds when working in AC driving power supply and DC driving power supply state, so that the AC / DC contactor control circuit of the application can be compatible with AC / DC use environment, and the use range and safety of the contactor in different environments are improved.

[0030] 4. By monitoring the attraction holding current through the contactor coil and the voltage across the contactor coil through the maintenance current feedback unit and the coil voltage feedback unit in real time, and feeding back the monitoring results to the PWM control unit, the attraction holding current through the contactor coil can be controlled in real time by the PWM control unit, so that the attraction holding current remains constant under different power supply states of the external driving power supply, while reducing the power consumption of the contactor coil, the contactor remains in a stable closing state, and when the excitation control module outputs an excitation trigger pulse, the feedback effect of the maintenance current feedback unit is shielded by the maintenance module shielding unit, so that a large current excitation driving current can be formed. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The control principle block diagram of an embodiment of the application.

[0032] Figure 2 The circuit principle diagram of the AC / DC power supply module in an embodiment of the application.

[0033] Figure 3 The circuit principle diagram of the voltage detection module in an embodiment of the application.

[0034] Figure 4 The circuit principle diagram of the excitation control module in an embodiment of the application.

[0035] Figure 5 The circuit principle diagram of the closing maintenance module in an embodiment of the application.

[0036] Figure 6Circuit schematic diagram of driving output module in one embodiment of the present application.

[0037] Figure 7 Waveform diagram of energizing drive current in contactor coil under DC rated voltage power supply state of external drive power supply in one embodiment of the present application.

[0038] Figure 8 Waveform diagram of closing holding current in contactor coil under DC rated voltage power supply state of external drive power supply in one embodiment of the present application.

[0039] Figure 9 Waveform diagram of energizing drive current in contactor coil under DC 80% rated voltage power supply state of external drive power supply in one embodiment of the present application.

[0040] Figure 10 Waveform diagram of closing holding current in contactor coil under DC 80% rated voltage power supply state of external drive power supply in one embodiment of the present application.

[0041] Figure 11 Waveform diagram of energizing drive current in contactor coil under DC 110% rated voltage power supply state of external drive power supply in one embodiment of the present application.

[0042] Figure 12 Waveform diagram of closing holding current in contactor coil under DC 110% rated voltage power supply state of external drive power supply in one embodiment of the present application.

[0043] BRIEF DESCRIPTION OF THE DRAWINGS: 1, AC / DC power supply module; 11, external drive power supply interface; 12, EMI protection unit; 13, rectification unit; 14, contactor coil power supply unit; 15, fast establishment power supply unit; 16, working power supply unit; 17, DC output unit; 18, reference voltage unit; 19, fast discharge unit; 2, voltage detection module; 21, AC signal extraction unit; 22, under-voltage protection unit; 23, over-voltage protection unit; 3, excitation control module; 31, excitation pulse forming unit; 32, excitation drive unit; 33, holding mode control unit; 4, closing maintenance module; 41, PWM control unit; 42, PWM suppression unit; 43, feedback adjustment unit; 5, driving output module; 51, coil drive unit; 52, coil voltage feedback unit; 53, coil current monitoring unit; 54, excitation current limiting unit; 55, drive tube short-circuit protection unit; 56, fast shutdown unit; 6, contactor coil. DETAILED DESCRIPTION

[0044] The specific embodiments of the present application will be described in detail hereinafter with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and explanatory and are not intended to limit the present application.

[0045] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "set", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] In the present specification, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features, therefore, the features limited by "first", "second" can be explicitly or implicitly include one or more of the features.

[0047] One embodiment of the AC-DC contactor control circuit of the present application, as shown in Figure 1 , includes an AC-DC power module 1, a voltage detection module 2, an excitation control module 3, a closing and maintaining module 4 and a driving output module 5. As shown in Figure 2 , the AC-DC power module 1 is provided with an external driving power supply interface 11, and can be connected with an external driving power supply through the external driving power supply interface 11, and the external driving power supply is introduced into the AC-DC power module 1. The AC-DC power module 1 can control the conversion of AC power and DC power, and generate a DC power suitable for the working requirements of different modules, therefore, the AC-DC contactor control circuit of the present application can be used in different external AC-DC power supply environments, for controlling different AC-DC contactors.

[0048] The voltage detection module 2 is connected with the external driving power supply interface 11, the excitation control module 3 and the closing and maintaining module 4 respectively, and the voltage detection module 2 can detect whether the external driving power supply introduced through the external driving power supply interface 11 is an AC power supply or a DC power supply, and generate a trigger signal in different proportion of the level state when the external driving power supply is an AC power supply or a DC power supply, trigger the excitation control module 3 to work, and control the working state of the closing and maintaining module 4.

[0049] The excitation control module 3 is connected with the closing and maintaining module 4 and the driving output module 5, and the excitation control module 3 can generate an excitation control signal lasting for a set time, control the driving output module 5 to act through the excitation control signal, and quickly generate a large current excitation driving current. The excitation control module 3 can also generate a control signal to control the working state of the closing and maintaining module 4, to ensure the maintenance of the large excitation driving current.

[0050] The closing-maintenance module 4 is connected with the driving output module 5, and the closing-maintenance module 4 can generate a maintenance control signal after the contactor is attracted, and control the driving output module 5 to generate a small closing-maintenance current required for maintaining the closing state of the contactor.

[0051] The driving output module 5 is connected with the contactor coil, and the driving output module 5 can generate a large excitation driving current under the control of the excitation control signal of the excitation control module 3, and the large excitation driving current flows through the contactor coil 6 to drive the contactor to be quickly and reliably attracted; and the driving output module 5 can also generate a small and constant closing-maintenance current under the control of the maintenance control signal generated by the closing-maintenance module 4, and the small and constant closing-maintenance current flows through the contactor coil to maintain the closing state of the contactor after the contactor is closed, so as to reduce the power loss of the contactor in the closing state and improve the service life of the contactor while ensuring the reliable closing of the contactor.

[0052] In some embodiments of the AC-DC contactor control circuit of the present application, as shown in Figure 2 The AC-DC power module 1 includes an EMI protection unit 12, a rectification unit 13, a contactor coil power supply unit 14, a fast power establishment unit 15, a working power supply unit 16, a DC output unit 17 and a reference voltage unit 18. The EMI protection unit 12 is connected with the external driving power supply interface 11, and is used to provide overload protection for the AC-DC power module 1, and can prevent the damage of the rear circuit when there is electromagnetic interference at the input end.

[0053] A specific EMI protection unit 12 includes a fuse F1, a pressure-sensitive resistor RV1, safety capacitors CX1, CX3 and a common-mode inductor L1, and the fuse F1 and the pressure-sensitive resistor RV1 can form overcurrent and overvoltage protection for the input power supply, respectively; the common-mode inductor L1, together with the safety capacitors CX1, CX3 at both ends thereof, forms a Π-type filter circuit, which can improve the electromagnetic compatibility (EMC) of the AC-DC power module 1 and suppress the electromagnetic interference (EMI) suffered by the AC-DC power module 1.

[0054] The rectification unit 13 is connected with the EMI protection unit 12, and is used to rectify the AC power supply introduced from the external driving power supply to form a DC power supply; when the external driving power supply is a DC power supply, the DC power supply can also pass through the rectification unit 13. Therefore, no matter whether the external driving power supply provides an AC power supply or a DC power supply, the power supply after passing through the rectification unit 13 is a DC power supply.

[0055] The rectification unit 13 can adopt various electronic elements or combinations of electronic elements that can play a rectification role, and in the present embodiment, a rectification bridge D12 is used. A capacitor CX4 can also be connected at the output end of the rectification unit 13 to filter the DC power output by the rectification unit 13 and remove high-frequency harmonics therein.

[0056] The contactor coil power supply unit 14 is connected to the output of the rectifier unit 13, and is used to provide a power supply with multiple protection functions for the contactor coil, so as to ensure the driving current of the contactor coil and the safety of the contactor coil.

[0057] The quick establishment power supply unit 15 is connected to the output of the rectifier unit 13, and can quickly establish the power required for the operation of the control circuit after the AC / DC power supply module 1 is powered on, so as to ensure the quick response of the control circuit and the quick closing of the contactor, and can be cut off after the working power supply unit 16 is established, so as to ensure that the control circuit works more stably under the power supply of the working power supply unit 16 with larger power supply and better voltage stability.

[0058] A specific quick establishment power supply unit 15 includes a resistor 20, a resistor 19, a MOS tube Q4, a diode D9, a voltage stabilizing diode D8, a resistor R21, a resistor R22, a triode Q6, a voltage stabilizing diode D10 and a voltage stabilizing diode D11. The resistor 20 is connected between the drain of the MOS tube Q4 and the positive output of the rectifier unit 13, and is used to limit the drain current of the MOS tube Q4, and the negative output of the rectifier unit 13 is grounded. The resistor 19 is connected between the positive output of the rectifier unit 13 and the gate of the MOS tube Q4, and is used to form the turn-on voltage of the MOS tube Q4, so as to ensure the turn-on of the MOS tube Q4 and form the current output of the quick establishment power supply unit 15. The diode D9 is connected between the source of the MOS tube Q4 and the DC output unit 17, so as to deliver the quick establishment power supply output through the source of the MOS tube Q4 to the DC output unit 17 and output through the DC output unit 17. The voltage stabilizing diode D10 and the voltage stabilizing diode D11 are connected in series between the gate of the MOS tube Q4 and the ground, the collector of the triode Q6 is connected between the voltage stabilizing diode D10 and the voltage stabilizing diode D11, the emitter of the triode Q6 is grounded, the base of the triode Q6 is connected to the working power supply unit 16 through the resistor R21 and the voltage stabilizing diode D8, and the resistor R22 is connected between the base and the emitter of the triode Q6, and is used to form the turn-on voltage of the triode Q6.

[0059] After the AC / DC power supply module 1 is powered on, there is no large-capacity capacitor in the EMI protection unit 12 and the rectifier unit 13, and the output of the rectifier unit 13 quickly forms a voltage output. There is also no large-capacity capacitor in the front and rear loops of the MOS tube Q4, and the MOS tube Q4 quickly turns on under the voltage division of the resistor R19, and quickly forms a power supply output through the diode D9. Through this circuit, the output of the quick establishment power supply can usually be formed within 3-5 ms, which ensures the quick start of the control circuit and ensures that the AC / DC contactor control circuit of the application can quickly form the exciting current for driving the contactor to close after the contactor coil power supply unit 14 is started, thereby improving the closing response speed of the contactor.

[0060] Because there is no large capacity capacitor in the front and back loop of MOS tube Q4, the ripple in the output power supply of MOS tube Q4 is large, and the stability of the power supply is not high, so the working power supply unit 16 is needed to form a stable output to cut off the working of the fast establishment power supply unit 15, and the working stability of the control circuit is ensured by the working power supply unit 16. The output voltage of the working power supply unit 16 is guided to the base of the transistor Q6 through the voltage stabilizing diode D8 and the resistor R21, the transistor Q6 is turned on under the voltage division of the resistor R22, the collector potential of the transistor Q6 is lowered, and is transmitted to the gate of the MOS tube Q4 through the voltage stabilizing diode D10, the gate potential of the MOS tube Q4 is lowered, and the MOS tube Q4 is cut off, so the fast establishment power supply unit 15 no longer has power output.

[0061] The working power supply unit 16 is connected to the output end of the rectifying unit 13, and is used to form a stable DC power supply for driving the control circuit. A specific working power supply unit 16 includes a resistor R18, a diode D4, a capacitor CD1, a voltage stabilizing integrated block U1, a resistor R23, a resistor R25, a resistor R24, a capacitor C4, a diode D5, a primary coil TP1-NP of a pulse transformer TP1, a diode D6, a diode D7 and a capacitor CD2. The resistor R18, the diode D4 and the capacitor CD1 are connected in series between the positive and negative output ends of the rectifying unit 13, the voltage stabilizing integrated block U1 is an off-line non-isolated switch type stabilizer KP3211, the 5, 6, 7 and 8 pins of the voltage stabilizing integrated block U1 are connected between the diode D4 and the capacitor CD1, the resistor R23 is connected between the 2 and 4 pins of the voltage stabilizing integrated block U1, the resistor R25 is connected between the 2 and 3 pins of the voltage stabilizing integrated block U1, the resistor R24 is connected between the 1 and 3 pins of the voltage stabilizing integrated block U1, one end of the primary coil TP1-NP of the pulse transformer TP1 is connected to the 2 pin of the voltage stabilizing integrated block U1, the other end is connected to the DC output unit 17 through the diode D7, the positive electrode of the diode D5 is grounded, the negative electrode is connected to the 2 pin of the voltage stabilizing integrated block U1, the capacitor CD2 is connected between the connection end of the primary coil TP1-NP of the pulse transformer TP1 and the diode D7 and the ground, the positive electrode of the diode D6 is connected to the primary coil TP1-NP of the pulse transformer TP1, and the negative electrode is connected to the 1 pin of the voltage stabilizing integrated block U1.

[0062] After the AC / DC power module 1 is powered on, the output power of the rectifier unit 13 charges the capacitor CD1 through the resistor R18 and the diode D4, and the positive potential of the capacitor CD1 gradually rises. When the positive potential of the capacitor CD1 reaches the potential required for the operation of the voltage stabilizing integrated block U1, the voltage stabilizing integrated block U1 operates, and outputs a PWM pulse through the pin 2 of the voltage stabilizing integrated block U1 to charge the primary coil TP1-NP of the pulse transformer TP1 and the capacitor CD2, so that a stable output voltage is formed across the capacitor CD2. The output voltage is fed back to the pin 3 of the voltage stabilizing integrated block U1 through the diode D6 and the voltage division of the resistor R24 and the resistor R25, so as to ensure the stability of the voltage across the capacitor CD2.

[0063] The stable output voltage across the capacitor CD2 is usually established in about 15 ms after the power is turned on. After the voltage across the capacitor CD2 reaches the set value, the positive potential of the capacitor CD2 is transmitted to the base of the transistor Q6 through the voltage stabilizing diode D8 and the resistor R21, the transistor Q6 is turned on, the MOS transistor Q4 is turned off, the voltage establishing unit 15 stops outputting, and the switching to the operating power unit 16 is performed.

[0064] The output voltage is transmitted to the DC output unit 17 through the diode D7, and is outputted through the DC output unit 17.

[0065] The DC output unit 17 is connected with the voltage establishing unit 15 and the operating power unit 16 respectively, and can receive the power from the voltage establishing unit 15 and the operating power unit 16 respectively to form a unified power VCC output for the operation of the control circuit. One DC output unit 17 includes the capacitor C5, the capacitor C17 and the resistor R68, which are connected in parallel across the output power, and the diode D9 and the diode D7 can prevent the mutual interference between the power from the voltage establishing unit 15 and the power from the operating power unit 16.

[0066] The reference voltage unit 18 is connected with the DC output unit 17, and is used to output a reference voltage E0 of a set size, such as 2.5 V, as a reference voltage in the control circuit.

[0067] One specific reference voltage unit 18 includes the resistor R26, the reference voltage chip U3 and the capacitor CD4. The reference voltage chip U3 can use TLV431. The resistor R26 is connected in series with the reference voltage chip U3 between the power VCC and the ground. The capacitor CD4 is connected in parallel across the reference voltage chip U3, and outputs the reference voltage E0 of 2.5 V at the positive electrode of the capacitor CD4.

[0068] In one preferred embodiment of the AC / DC contactor control circuit of the present application, as shown in Figure 2As shown, the contactor coil power supply unit 14 includes a power supply protection subunit, an output control subunit and a fuse device. A power supply protection subunit includes a PTC resistor RF1 and a pressure sensitive resistor RV2, one end of the PTC resistor RF1 is connected to the positive output end of the rectifier unit 13, the other end is connected with the pressure sensitive resistor RV2, the other end of the pressure sensitive resistor RV2 is connected to the ground. The output control subunit is connected between the PTC resistor RF1 and the pressure sensitive resistor RV2, when the output current of the output control subunit is too large, the resistance of the PTC resistor RF1 rapidly increases, the input current of the output control subunit rapidly decreases, preventing the current overload of the output control subunit; when the output voltage of the rectifier unit 13 is too high, the resistance of the pressure sensitive resistor RV2 rapidly decreases, the input voltage of the control subunit rapidly decreases, preventing the contactor coil from being damaged due to the output voltage of the control subunit being too high.

[0069] A specific control subunit includes a MOS tube Q1, a resistor R30, a voltage stabilizing diode D14, a resistor R31, a capacitor C7, a capacitor CD3, a resistor R29, a diode D13 and a second secondary coil TP1-NS2 of a pulse transformer TP1, the resistor R29, the diode D13 and the second secondary coil TP1-NS2 of the pulse transformer TP1 are connected in series, the capacitor CD3 is connected in parallel between the two ends of the series circuit composed of the resistor R29, the diode D13 and the second secondary coil TP1-NS2 of the pulse transformer TP1, the resistor R30 and the voltage stabilizing diode D14 are connected in series between the gate and the source of the MOS tube Q1, the resistor R31 and the capacitor C7 are connected in series between the drain and the source of the MOS tube Q1, the positive pole of the capacitor CD3 is connected between the resistor R30 and the voltage stabilizing diode D14, the negative pole is connected with the source of the MOS tube Q1, the drain of the MOS tube Q1 is connected between the PTC resistor RF1 and the pressure sensitive resistor RV2. The capacitor CX5 is connected between the source of the MOS tube Q1 and the ground, the fuse device uses a fuse F2, the fuse F2 is connected between the source of the MOS tube Q1 and the contactor coil power supply output power VXG. A group of control signal input nodes GATE1 and HGND are arranged between the gate and the source of the MOS tube Q1.

[0070] After the working power supply unit 16 works, a pulse current is generated in the primary coil TP1-NP of the pulse transformer TP1, an induced current is generated in the second secondary coil TP1-NS2 of the pulse transformer TP1, the induced current is rectified by the diode D13, filtered by the capacitor CD3, and limited by the voltage stabilizing diode D14, and then applied between the gate and the source of the MOS tube Q1, triggering the MOS tube Q1 to conduct, the current from the rectifier unit 13 passes through the PTC resistor RF1, the MOS tube Q1 and the fuse F2, and outputs the contactor coil power supply output power VXG.

[0071] The AC-DC power module 1 further comprises a fast discharge unit 19, and a specific fast discharge unit 19 comprises a diode D3, a capacitor C2, a resistor R3 and a resistor R3A. The diode D3 and the capacitor C2 are connected in series at the output of the rectifier unit 13, and the resistor R3 and the resistor R3A are connected in series and then connected in parallel at both ends of the capacitor C2, and the power HVIN is output from between the diode D3 and the capacitor C2.

[0072] After the AC-DC power module 1 is powered on, the power output by the rectifier unit 13 charges the capacitor C2 through the diode D3, and the power HVIN is output after being filtered by the capacitor C2. After the AC-DC power module 1 is powered off, the energy stored on the power HVIN circuit, the capacitors CX1, L1 and CX3 in the EMI protection unit 12, the capacitor CX4 in the rectifier unit 13, and the energy stored in the capacitor C2 are quickly discharged through the fast discharge circuit composed of the resistor R3 and the resistor R3A, so as to ensure that the contactor contacts are quickly disconnected, and the rapid and reliable operation of the contactor closing-opening-closing is ensured.

[0073] In some embodiments of the AC-DC contactor control circuit of the present application, as shown in Figure 3 The voltage detection module 2 comprises an AC signal extraction unit 21 and an under-voltage protection unit 22. The AC signal extraction unit 21 is connected to the external driving power source interface 11 through the two connection points +KM / L and -KM / N, and is used to extract an AC signal from the external driving power source, so as to determine whether the external driving power source is an AC power source according to whether the AC signal can be extracted from the external driving power source. The under-voltage protection unit 22 is connected to the AC signal extraction unit 21, the AC-DC power module 1 and the excitation control module 3, and can output a control signal to control the excitation control module 3 to start under the condition that the external driving power source is an AC power source or a DC power source and the fast discharge unit 19 outputs different fast discharge power voltage states. When the voltage of the external driving power source is too low and the voltage of the fast discharge power output by the fast discharge unit 19 cannot reach the corresponding value, the under-voltage protection unit 22 outputs a control signal to control the excitation control module 3 to stop working, so as to prevent the contactor contacts from being attracted under a low voltage state, thereby playing an under-voltage protection role.

[0074] A specific AC signal extraction unit 21 comprises a capacitor CX2, a rectifier bridge D1, a voltage stabilizing diode D2, a capacitor C1, a resistor R1 and an optical coupler OT1. The input end of the rectifier bridge D1 is connected in series with the capacitor CX2, and then connected to the external driving power source interface 11 through the two connection points +KM / L and -KM / N. The voltage stabilizing diode D2 and the capacitor C1 are connected in parallel at the output end of the rectifier bridge D1. The input end of the optical coupler OT1 is connected to the output end of the rectifier bridge D1 after being connected in series with the resistor R1. The output end of the optical coupler OT1 is connected to the under-voltage protection unit 22.

[0075] If the external driving power supply is an AC power supply, the AC signal flows through the capacitor CX2 to the rectifier bridge Dl through the external driving power supply interface 11, is rectified into a DC signal by the rectifier bridge Dl, is stabilized by the voltage stabilizing diode D2, and is filtered by the capacitor Cl to drive the light emitting diode of the input end of the optocoupler OTl to emit light, and the optocoupler OTl is turned on. If the external driving power supply is a DC power supply, no current is input to the input end of the optocoupler OTl due to the direct current isolation of the capacitor CX2, and the optocoupler OTl is turned off.

[0076] The under-voltage protection unit 22 includes the resistor R12, the resistor R13, the transistor Q12, the resistor R10, the resistor R9, the resistor R11, the potentiometer W2, the resistor R15, the resistor R16, the reference voltage chip U4, the capacitor C3, the resistor R14, the diode D23, and the transistor Q13. The resistor R12 and the resistor R13 are connected in series between the emitter of the output end of the optocoupler OTl and the ground, the collector of the output end of the optocoupler OTl is connected to the power supply VCC, the base of the transistor Q12 is connected between the resistor R12 and the resistor R13, the emitter of the transistor Q12 is grounded, the resistor R9, the resistor R11, and the potentiometer W2 are connected in series between the power supply HVIN and the ground, one end of the resistor R10 is connected to the collector of the transistor Q12, and the other end of the resistor R10 is connected between the resistor R9 and the resistor R11. The reference voltage chip U4 is connected in series with the resistor R15 and the resistor R16 between the power supply VCC and the ground, the capacitor C3 is connected in parallel between the control pin and the cathode pin of the reference voltage chip U4, the control pin of the reference voltage chip U4 is connected between the resistor R9 and the resistor R11. The base of the transistor Q13 is connected between the resistor R15 and the resistor R16, the emitter of the transistor Q13 is connected to the power supply VCC, the collector of the transistor Q13 is connected to the excitation control module 3 and the anode of the diode D23, the cathode of the diode D23 is connected to the resistor R14, and the other end of the resistor R14 is connected between the resistor R9 and the resistor R11. The collector of the transistor Q13 is connected to the excitation control module 3 through the connection point X1.

[0077] If the external driving power supply is a DC power supply, the AC signal extraction unit 21 does not extract the AC signal, the optocoupler OTl is turned off, the transistor Q12 is turned off, the power supply HVIN is divided by the resistor R9, the resistor R11, and the potentiometer W2, and a potential V1 is formed at the connection point between the resistor R9 and the resistor R11. When the voltage of the external driving power supply reaches the set DC voltage requirement, the potential of V1 is greater than 2.5V, the reference voltage chip U4 is turned on, the transistor Q13 is turned on, the potential of the collector of the transistor Q13 approaches VCC, the connection point X1 outputs a high level to control the excitation control module 3 to work, and the contactor contact is driven to be attracted.

[0078] When the voltage of the external driving power supply is lower than the set DC voltage requirement, the potential of V1 is less than 2.5V, the reference voltage chip U4 is cut off, the triode Q13 is cut off, the collector potential of the triode Q13 is close to zero, the connection point X1 outputs low level control to stop the work of the excitation control module 3, the driving contactor contact is disconnected, and the under-voltage protection of the external input power supply is formed to prevent the load from being damaged due to the failure of the contactor to work normally in the low-voltage state.

[0079] If the external driving power supply is an AC power supply, the AC signal extracted by the AC signal extraction unit 21 makes the optocoupler OT1 conduct, the power supply VCC passes through the collector-emitter of the optocoupler OT1 to drive the triode Q12 to conduct, the power supply HVIN passes through the parallel circuit of the resistors R9, R11 and the potentiometer W2 and the resistor R10 to form different voltage division ratios, and the potential V1 is formed at the connection point between the resistors R9 and R11. When the voltage of the external driving power supply reaches a different set AC voltage requirement, the connection point X1 outputs high level control to drive the excitation control module 3 to work, and the contactor contact is attracted; when the voltage of the external driving power supply is lower than the set AC voltage requirement, the connection point X1 outputs low level control to stop the work of the excitation control module 3, and the contactor contact is disconnected, thereby forming the under-voltage protection when the external input power supply is an AC power supply and is lower than the different voltage. Thus, the under-voltage protection is formed when the external driving power supply is a DC power supply and an AC power supply and is lower than different voltage values.

[0080] By adjusting the potentiometer W2, the voltage division ratio of the power supply HVIN at the connection point between the resistors R9 and R11 can be adjusted, the value of the potential V1 is finely adjusted, and the under-voltage protection trigger voltage value of the contactor is accurately controlled.

[0081] In a preferred embodiment of the AC / DC contactor control circuit of the present application, as shown in Figure 2 The over-voltage protection unit 23 is further provided in the voltage detection module 2, and is connected with the AC signal extraction unit 21, the reference voltage unit 18 and the closing maintenance module 4. When the voltage of the external driving power supply exceeds the set range, the over-voltage protection unit 23 controls the closing maintenance module 4 to act, cuts off the output of the driving output module 5, and thus makes the contactor contact disconnected.

[0082] A specific overvoltage protection unit 23 includes resistance R7, resistance R8, triode Q11, resistance R5, resistance R4B, resistance R4A, resistance R4, resistance R6, potentiometer W1, operational amplifier U5B, resistance R93, resistance R55, diode D25, diode D26 and resistance R59. One end of resistance R8 is connected to the emitter of the output terminal of photo-coupler OT1, the other end is connected to the base of triode Q11, resistance R7 is connected between the base and the emitter of triode Q11, the emitter of triode Q11 is grounded, resistance R4B, resistance R4A, resistance R4, resistance R6 and potentiometer W1 are connected in series between power supply HVIN and ground, one end of resistance R5 is connected to the collector of triode Q11, the other end is connected between resistance R4 and resistance R6, the positive input terminal of operational amplifier U5A is connected between resistance R4 and resistance R6, the negative input terminal is connected to 2.5V reference voltage E0 through resistance R93, resistance R55 and diode D25 are connected in series and then connected between the output terminal and the positive input terminal of operational amplifier U5A, the output terminal of operational amplifier U5A is connected to connection point X2 through diode D26 and resistance R59, and is connected to closing and maintaining module 4 through connection point X2.

[0083] If the external driving power supply is a direct current power supply, photo-coupler OT1 is cut off, the base of triode Q11 is in a low potential state, triode Q11 is cut off, power supply HVIN is divided by the voltage dividing circuit composed of resistance R4B, resistance R4A, resistance R4, resistance R6 and potentiometer W1, and a potential V2 is formed at the connection point of resistance R4 and resistance R6. When the external driving power supply is normally powered, the potential of V2 is less than 2.5V, operational amplifier U5B outputs low level, which is transmitted to closing and maintaining module 4 through connection point X2, and closing and maintaining module 4 works normally. Once the direct current voltage of the external driving power supply is higher than the set threshold value, usually higher than 1.5 times the rated voltage, the potential of V2 is greater than 2.5V, U5B outputs high level, which is transmitted to closing and maintaining module 4 through connection point X2, controls the working state of closing and maintaining module 4, stops the power supply of contactor coil through driving output module 5, and the contactor contact is disconnected, forming overvoltage protection effect.

[0084] If the external driving power supply is an AC power supply, the optocoupler OT1 is turned on, the power supply VCC is turned on through the collector-emitter of the optocoupler OT1 to drive the transistor Q11, the power supply HVIN forms a voltage dividing circuit with different voltage dividing ratios through the parallel connection of the resistor R4B, the resistor R4A, the resistor R4, the resistor R6 and the resistor R5, and a voltage V2 is formed at the connection point of the resistor R4 and the resistor R6. When the AC voltage of the external driving power supply is normal, V2 is less than 2.5V, the operational amplifier U5B outputs a low level, which is transmitted to the closing and maintaining module 4 through the connection point X2, and the closing and maintaining module 4 works normally. Once the AC voltage of the external driving power supply is higher than a different set threshold, usually 1.5 times higher than the rated AC voltage, V2 is greater than 2.5V, the operational amplifier U5B outputs a high level, which is transmitted to the closing and maintaining module 4 through the connection point X2 to control the working state of the closing and maintaining module 4, and the driving output module 5 stops supplying power to the contactor coil, the contactor contacts are disconnected, and overvoltage protection of the external driving power supply under different voltages is formed. Thus, overvoltage protection of the contactor under different voltage thresholds can be realized when the external driving power supply is under AC and DC power supply states.

[0085] By adjusting the potentiometer W1, the voltage dividing ratio of the power supply HVIN at the connection point of the resistor R4 and the resistor R6 can be adjusted, the value of the voltage V2 can be finely adjusted, and the overvoltage protection trigger voltage value of the contactor can be accurately controlled.

[0086] In some embodiments of the AC-DC contactor control circuit of the present application, as shown in Figure 4 The excitation control module 3 includes an excitation pulse forming unit 31, an excitation drive unit 32 and a maintaining mode control unit 33. The excitation pulse forming unit 31 is connected with the voltage detection module 2 and can generate an excitation trigger pulse with a set width when the power supply state of the external driving power supply is normal. The excitation drive unit 32 is connected between the excitation pulse forming unit 31 and the driving output module 5 and can generate an excitation control signal with the same duration as the excitation trigger pulse under the control of the excitation trigger pulse and transmit the excitation control signal to the driving output module 5 through the connection point X4.

[0087] The maintaining mode control unit 33 is connected between the excitation pulse forming unit 31 and the closing and maintaining module 4 and the driving output module 5. The maintaining mode control unit 33 is provided with an excitation mode selection switch, which can select different signals in the excitation pulse forming unit 31 to be transmitted to the closing and maintaining module 4 to control the working state of the closing and maintaining module 4 in different ways.

[0088] A specific excitation pulse forming unit 31 includes resistor R17, potentiometer W3, capacitor C13, diode D24, resistor R51, operational amplifier U4B, resistor R48, resistor R49, triode Q14 and resistor R54. Resistor R17, potentiometer W3 and capacitor C13 are connected in series between connection point X1 and ground, the positive electrode of diode D24 is connected to the positive input terminal of operational amplifier U4B, the negative electrode is connected to power supply VCC, the connection point of potentiometer W3 and capacitor C13 is connected to the positive input terminal of operational amplifier U4B, resistor R51 is connected between 2.5V reference voltage E0 and the negative input terminal of operational amplifier U4B, the output terminal of operational amplifier U4B is connected to the base electrode of triode Q14 through resistor R48, resistor R49 is connected between the base electrode and the emitter electrode of triode Q14, the collector electrode of triode Q14 is connected to connection point X1 through resistor R54, and the emitter electrode of triode Q14 is grounded. The collector electrode of triode Q14 is also connected to connection point X5, and is connected to closing maintaining module 4 through connection point X5.

[0089] A specific excitation drive unit 32 includes resistor R53, resistor R52 and operational amplifier U5A, resistor R53 is connected between the collector electrode of triode Q14 and the positive input terminal of operational amplifier U5A, resistor R52 is connected between 2.5V reference voltage E0 and the negative input terminal of operational amplifier U5A, the output terminal of operational amplifier U5A is connected to connection point X4, and is connected to one connection point in drive output module 5 through connection point X4, to control drive output module 5 to output large current excitation drive current; the positive input terminal of operational amplifier U5A is also connected to connection point X6, and is connected to another connection point in drive output module 5 through connection point X6, to control the working state of operational amplifier U5A by using signals from drive output module 5.

[0090] The holding mode control unit 33 selects four-contact double-position toggle switch S1, when toggle switch S1 is toggled to the first working position (electrical holding position), contact 1 and contact 4 are connected and contact 2 and contact 3 are disconnected, and when toggle switch S1 is toggled to the second working position (mechanical holding position), contact 2 and contact 3 are connected and contact 1 and contact 4 are disconnected. Contact 1 of toggle switch S1 is connected to connection point X1, contact 2 is connected to the collector electrode of triode Q14, contact 3 and contact 4 are connected to each other and are connected to connection point X3 through connection point X3, and are connected to closing maintaining module 4 and drive output module 5 respectively through connection point X3.

[0091] When the voltage of the external driving power supply is higher than the set under-voltage protection threshold, the connection point X1 outputs a high potential, and starts to charge the capacitor C13 through the resistor R17 and the potentiometer W3. When the capacitor C13 starts to charge, the positive input terminal of the operational amplifier U4B is at a low potential, which is less than the potential of 2.5V at the negative input terminal of the operational amplifier U4B, and the output terminal of the operational amplifier U4B is at a low potential, so the triode Q14 is cut off, and the connection point X5 outputs a high potential signal to the closing and maintaining module 4, preventing the closing and maintaining module 4 from limiting the exciting current.

[0092] When the capacitor C13 is charged for a set time, usually after charging for 140-160 ms, the potential at the positive input terminal of the operational amplifier U4B exceeds 2.5V, the output terminal of the operational amplifier U4B changes to a high potential, the triode Q14 is turned on, and the connection point X5 outputs a low potential signal. In this way, a high potential positive pulse signal with a set time is output at the collector of the triode Q14, and the width of the output pulse signal can be adjusted by adjusting the potentiometer W3.

[0093] The high potential pulse signal output at the collector of the triode Q14 is transmitted to the positive input terminal of the operational amplifier U5A, and a high potential positive pulse signal with greater power is output after being amplified by the operational amplifier U5A, transmitted to the connection point X4, and transmitted to the driving output module 5 through the connection point X4, so as to control the driving output module 5 to output a large exciting current, flow through the contactor coil to drive the contactor contacts to be quickly closed, so that the contactor is quickly closed. The positive input terminal of the operational amplifier U5A is also connected to the driving output module 5 through the connection point X6, so as to be able to receive the feedback signal from the driving output module 5, control the output of the operational amplifier U5A to be at a low potential, and thus limit the maximum value of the exciting current output by the driving output module 5.

[0094] When the switch S1 is switched to the electric holding position, the contact 1 is connected to the contact 4, and when the voltage of the external driving power supply is normal, the high potential from the connection point X1 is directly output through the connection point X3, to control the closing and maintaining module 4 and the driving output module 5 to work normally, and to provide a closing holding current for the contactor coil after the exciting pulse signal stops, for the working mode of maintaining the closed state of the contactor after the electric holding type contactor is closed. When the switch S1 is switched to the mechanical holding position, the contact 2 is connected to the contact 3, and the connection point X3 outputs the potential at the collector of the triode Q14. After the exciting pulse signal stops, the collector of the triode Q14 outputs a low potential through the connection point X3, to control the closing and maintaining module 4 and the driving output module 5 to stop working, and no longer provide a current for the contactor coil, for the working mode of maintaining the closed state of the contactor after the mechanical holding type contactor is closed by using the mechanical structure. Therefore, the AC / DC contactor control circuit of the present application can be applied to contactors with different holding modes.

[0095] In a preferred embodiment of the AC / DC contactor control circuit of the present application, as shown in Figure 5As shown, the closing maintenance module 4 includes a PWM control unit 41, a PWM suppression unit 42, and a feedback adjustment unit 43. The PWM control unit 41 can use various circuit units capable of generating PWM control signals. The PWM control unit 41 is connected to the PWM suppression unit 42, the feedback adjustment unit 43, the voltage detection module 2, and the drive output module 5. Under the control of the PWM suppression unit 42, the feedback adjustment unit 43, the voltage detection module 2, and the feedback control signal from the drive output module 5, the PWM control unit 41 can change its operating state, control the generation of the PWM control signal, and adjust the duty cycle of the PWM control signal, thereby controlling the magnitude of the drive current generated by the drive output module 5.

[0096] The PWM suppression unit 42 is connected between the holding mode control unit 33 and the PWM control unit 41. It can enable the PWM control unit 41 to work normally during the excitation phase in both electric holding mode and mechanical holding mode, and control the PWM control unit 41 to stop working after the excitation phase ends in mechanical holding mode.

[0097] The feedback adjustment unit 43 is connected between the drive output module 5, the excitation pulse forming unit 31, and the PWM control unit 41. During the closing and holding phase, it can control the duty cycle of the PWM control signal generated by the PWM control unit 41 according to the magnitude of the drive current output by the drive output module 5, thereby stabilizing the closing and holding current output to the contactor coil at a small level. During the excitation phase, it blocks the feedback adjustment mechanism of the drive current output by the drive output module 5 on the PWM control unit 41, ensuring that the drive output module 5 can output a sufficiently large excitation drive current.

[0098] A specific PWM control unit 41, such as Figure 5 As shown, the system consists of integrated circuit U2 and its peripheral electronic components. Integrated circuit U2 uses a fixed-frequency pulse width chip TL494, which can generate PWM control signals with different duty cycles at pins 9 and 10 under the control of the input potentials at pins 1 and 16. These signals are output to the drive output module 5 through connection point X7 to control the magnitude of the drive current generated by the drive output module 5. Pins 1 and 16 of integrated circuit U2 are connected to connection points X8 and X9, respectively, and are connected to the drive output module 5 through connection points X8 and X9. Under the control of different feedback signals in the drive output module 5, it outputs PWM control signals with different duty cycles, forming negative feedback on the drive current output by the drive output module 5, ensuring the stability and controllability of the drive current output by the drive output module 5. Pin 4 of integrated circuit U2 is connected to connection point X2, and is connected to overvoltage protection unit 23 in voltage detection module 2 through connection point X2. When the voltage of external drive power supply is greater than the rated voltage setting amplitude, overvoltage protection unit 23 outputs a high potential signal to connection point X2, controlling PWM control unit 41 to stop outputting PWM control signal (duty cycle is 0).

[0099] A specific PWM suppression unit 42 includes resistor R71, resistor R97, transistor Q16, resistor R72 and diode D27, resistor R71 is connected between the base of transistor Q16 and connection point X3, resistor R97 is connected between connection point X3 and the emitter of transistor Q16, the collector of transistor Q16 is connected to power supply VCC through resistor R72, and is connected to pin 4 of integrated block U2 through diode D27.

[0100] When X3 outputs high potential, transistor Q16 is turned on, the collector of transistor Q16 outputs low potential, which ensures that PWM control unit 41 normally outputs PWM control signal in the excited state of the electric holding mode and the mechanical holding mode; when X3 outputs low potential, transistor Q16 is turned off, the high potential output by the collector of transistor Q16 is transmitted to pin 4 of integrated block U2 through diode D27, and integrated block U2 stops outputting PWM control signal, so that PWM control unit 41 stops working in the closing holding stage of the mechanical holding mode.

[0101] A specific feedback regulation unit 43 includes resistor R80, resistor R81, transistor Q18, capacitor C22 and resistor R82, the base of transistor Q18 is connected to connection point X5 through resistor R80, and is connected to excitation pulse forming unit 31 through connection point X5; resistor R81 is connected between the base and the emitter of transistor Q18, the emitter of transistor Q18 is grounded, the collector of transistor Q18 is connected to pin 1 of integrated block U2 and connection point X8, and is connected to driving output module 5 through connection point X8, capacitor C22 and resistor R82 are connected in parallel between the collector of transistor Q18 and the ground.

[0102] The driving current feedback signal from driving output module 5 is transmitted to pin 1 of integrated block U2 through connection point X8, which controls the duty cycle of the PWM driving signal output by pin 9 and pin 10 of integrated block U2, and feedback regulates the driving current output by driving output module 5, so as to stabilize the closing holding current for maintaining the closed state of the contactor at a set lower level. In the excitation stage of the contactor, the high potential signal output by excitation pulse forming unit 31 is transmitted to the base of transistor Q18 through connection point X5, so that transistor Q18 is turned on, the potential of pin 1 of integrated block U2 approaches 0, the PWM driving signal maintains the maximum duty cycle, the feedback regulation effect of the driving current feedback signal of driving output module 5 on the driving current is stopped, and the output of the large-current excitation driving current is ensured.

[0103] In some embodiments of the AC-DC contactor control circuit of the present application, as shown in FIG. 2, the feedback regulation unit 43 is connected to the driving output module 5 through connection point X8, and the feedback regulation unit 43 is connected to the excitation pulse forming unit 31 through connection point X5. Figure 6As shown, the drive output module 5 includes a coil drive unit 51, a coil voltage feedback unit 52, a coil current monitoring unit 53, an excitation current limiting unit 54, and a drive tube short circuit protection unit 55. The coil drive unit 51 is connected to the excitation control module 3, the closing maintenance module 4, and the contactor coil KM, and can work at full power under the control of the excitation control signal generated by the excitation control module 3, output a large current excitation drive current to the contactor coil KM, and drive the contactor contact to be attracted to quickly form a closed state. And can work in PWM state under the control of the maintenance control signal, that is, the PWM control signal generated by the closing maintenance module 4 when the contactor is in the closed state and there is no excitation control signal, output a small current closing maintenance current to the contactor coil KM, ensure that the contactor contact is maintained in the attracted state at a lower power, and ensure that the contactor is maintained in the closed state.

[0104] A specific coil drive unit 51 includes diode D28, diode D29, resistor R84, resistor R85, transistor Q7, transistor Q8, resistor R35, zener diode D15, resistor R34, transistor Q5, resistor R27, MOS tube Q3, capacitor C9, resistor R33, and diode D16. The bases of the transistors Q7 and Q8 are connected to each other, connected to the connection point X4 through the diode D28, and connected to the connection point X7 through the series circuit of the resistor R85 and the resistor R84, and the diode D29 is connected in parallel across the resistor R85 and the resistor R84. The connection point X4 is connected to the excitation drive unit 32, and the connection point X7 is connected to the PWM drive signal output point of the closing maintenance module 4. The emitters of the transistors Q7 and Q8 are connected to each other, connected to the gate of the MOS tube Q3 through the resistor R35, the collector of the transistor Q7 is connected to the bottom and connected to the connection point of the resistor R85 and the resistor R84, and the collector of the transistor Q8 is connected to the power supply VCC. The zener diode D15 and the resistor R34 are connected in parallel between the gate of the MOS tube Q3 and the ground, the collector of the transistor Q5 is connected to the gate of the MOS tube Q3, the emitter is connected to the ground, the resistor R27 is connected between the base of the transistor Q5 and the ground, the base of the transistor Q5 is connected to the source of the MOS tube Q3, the drain of the MOS tube Q3 is connected to one end of the contactor coil KM, the other end of the contactor coil KM is connected to the contactor coil power supply output power supply VXG, the resistor R33 and the capacitor C9 are connected in series between the drain and the source of the MOS tube Q3, and the diode D16 is connected in parallel across the resistor R33.

[0105] The PWM driving signal outputted by the PWM control unit 41 is transmitted to the base of the triode Q7 and the triode Q8 through the connection point X7, and is transmitted to the gate of the MOS tube Q3 as the driving tube after being amplified by the triode Q7 and the triode Q8, so as to control the on-time ratio of the MOS tube Q3, and thus control the size of the equivalent driving current outputted by the coil driving unit 51.

[0106] In the excitation stage of the contactor, the high potential excitation trigger pulse generated by the excitation pulse forming unit 31 is transmitted to the positive input terminal of the operational amplifier U5A, and is transmitted to the base of the triode Q8 through the connection point X6, so that the triode Q8 keeps in the on state, and the MOS tube Q3 also keeps in the on state, and the coil driving unit 51 outputs the full-power large current excitation driving current, shielding the control of the output current by the PWM driving signal.

[0107] The triode Q5 and the resistor R27 constitute a contactor coil short circuit protection circuit. When the contactor coil KM is short-circuited, the current at the source of the MOS tube Q3 increases, and the source potential of the MOS tube Q3 increases rapidly. When the source potential of the MOS tube Q3 is greater than the Vbe voltage of the triode Q5, the triode Q5 is turned on, the gate potential of the MOS tube Q3 decreases, and the MOS tube Q3 is turned off, thereby preventing the risk of fire caused by the short circuit of the contactor coil KM.

[0108] The coil voltage feedback unit 52 is connected in parallel across the power supply circuit of the contactor coil KM, and can extract the voltage applied across the contactor coil KM, generate a voltage feedback signal corresponding to the size of the voltage across the contactor coil KM, and transmit the voltage feedback signal to the closing and maintaining module 4 through the connection point X9. The closing and maintaining module 4 forms a negative feedback to the coil driving unit 51, so as to control the size of the excitation driving current.

[0109] A specific coil voltage feedback unit 52 includes the resistor R45A, the resistor R45, the resistor R44A, the resistor R44, the triode QA, the resistor R90, the resistor R89 and the capacitor C29. The emitter of the triode QA is connected between the contactor coil power supply output power VXG and the contactor coil KM through the resistor R45A and the resistor R45. The base of the triode QA is connected between the drain of the MOS tube Q3 and the contactor coil KM. The resistor R44A and the resistor R44 are connected in series between the base of the triode QA and the contactor coil power supply output power VXG. The resistor R90 and the resistor R89 are connected in series between the collector of the triode QA and the ground. The capacitor C29 is connected in parallel with the resistor R89. The connection point X9 is connected between the resistor R90 and the resistor R89.

[0110] When the voltage across the contactor coil KM is too high, the transistor QA is turned on, the collector potential of the transistor QA rises, and after the voltage division of the resistor R90 and the resistor R89, the potential of the connection point X9 is proportional to the voltage across the contactor coil KM, which is transmitted to the 16th pin of the integrated block U2 through the connection point X9. The integrated block U2 compares the potential of the 16th pin with the 2.5V reference potential input from the 15th pin, and adjusts the duty cycle of the PWM control signal output. When the potential of the connection point X9 is greater than the 2.5V reference potential, the duty cycle of the PWM control signal output by the integrated block U2 decreases, the conduction time of the MOS tube Q3 decreases, and the drive current output by the coil drive unit 51 decreases; when the potential of the connection point X9 is less than the 2.5V reference potential, the duty cycle of the PWM control signal output by the integrated block U2 is not affected, and the coil voltage feedback unit 52 does not work. It is mainly used to adjust the excitation drive current in the excitation stage.

[0111] The coil current monitoring unit 53 is connected in series between the contactor coil power supply output power VXG and the contactor coil KM, and is connected with the closing and maintaining module 4. The coil current monitoring unit 53 can monitor the size of the current flowing through the contactor coil KM, generate a feedback signal corresponding to the current of the contactor coil KM, and transmit it to the closing and maintaining module 4. Through the closing and maintaining module 4, a negative feedback is formed to the coil drive unit 51, so that the size of the closing and maintaining current is maintained, and the stability of the closing and maintaining current is maintained.

[0112] A specific coil current monitoring unit 53 includes a resistor R95, a resistor R96, a diode D35, a transistor QB, a resistor R94, a resistor R91 and a resistor R91A. The resistor R95, the resistor R96 and the diode D35 are connected in parallel and then connected in series between the contactor coil power supply output power VXG and the contactor coil KM. The resistor R94 is connected between the base of the transistor QB and the contactor coil KM. The collector of the transistor QB is connected to the connection point X8 through the resistor R91 and the resistor R91A, and is connected to the closing and maintaining module 4 through the connection point X8, and is connected to the 1st pin of the integrated block U2.

[0113] The current flowing through the contactor coil KM generates a voltage drop proportional to the current size across the resistor R95 and the resistor R96, which acts between the emitter and the base of the transistor QB, generating a base current proportional to the current of the contactor coil KM. After being amplified by the transistor QB, the collector current flowing through the resistor R82 and the resistor R91, the resistor R91A in the closing and maintaining module 4 generates a potential proportional to the current of the contactor coil KM at the connection point X8.

[0114] When the current flowing through the contactor coil KM is large, the diode D35 can provide a large current path, at this time the voltage drop across the diode D35 is only 1-1.2V, so that the voltage across the resistor R95 and the resistor R96 is also only 1-1.2V, preventing the current flowing through the resistor R95 and the resistor R96 too large, resulting in the resistor R95, resistor R96 and even the damage of the transistor QB.

[0115] When the potential of the connection point X8 is greater than the 2.5V reference potential of the 2-pin of the integrated block U2, the duty cycle of the PWM control signal output by the integrated block U2 decreases with the increase of the potential of the 1-pin of the integrated block U2, and the drive current output by the coil drive unit 51 decreases accordingly, ensuring that the current flowing through the contactor coil KM is stable at the set value. In the excitation stage, the positive input terminal potential of the operational amplifier U5A in the excitation drive unit 32 is high, and the transistor Q18 in the feedback regulation unit 43 is turned on through the connection point X6, which forces the 1-pin potential of the integrated block U2 to be lower than 2.5V, so that the coil current monitoring unit 53 cannot play the role of current feedback regulation, and the excitation drive current can reach a large value.

[0116] The excitation current limiting unit 54 is connected with the coil drive unit 51 and the excitation control module 3, which can extract the signal related to the output current from the coil drive unit 51, generate a drive current limiting signal when the drive current output by the coil drive unit 51 reaches the first set value, and transmit it to the excitation control module 3 to control the working state of the excitation control module 3, limiting the maximum value of the drive current output by the coil drive unit 51 to the first set value.

[0117] A specific excitation current limiting unit 54 includes resistance R60, capacitor C15, capacitor C16, resistance R61, resistance R62, operational amplifier U5, resistance R58, resistance R63, diode D30, voltage stabilizing diode D31, resistance R57, resistance R56, triode Q15, and capacitor C14. Resistance R60 is connected between the positive input terminal of operational amplifier U5 and the drive tube of coil driving unit 51. The negative input terminal of operational amplifier U5 is connected to 2.5V reference voltage E0 through resistance R62. Resistance R61 is connected between the negative input terminal of operational amplifier U5 and ground. Capacitor C15 and capacitor C16 are respectively connected between the positive and negative input terminals of operational amplifier U5 and ground. The output terminal of operational amplifier U5 is connected to ground through resistance R58 and capacitor C14. Resistance R63 and diode D30 are connected in series between the connection terminal of resistance R58 and capacitor C14 and the positive input terminal of operational amplifier U5. Voltage stabilizing diode D31, resistance R57, and resistance R56 are connected in series and then in parallel across capacitor C14. The base of triode Q15 is connected to the connection between resistance R57 and resistance R56. The emitter of triode Q15 is connected to ground. The collector of triode Q15 is connected to connection point X6 and then to the positive input terminal of operational amplifier U5A in excitation control module 3 through connection point X6.

[0118] As the output current of the drive tube of coil driving unit 51 increases, the potential at the positive input terminal of operational amplifier U5 rises. When the potential at the positive input terminal of operational amplifier U5 rises to be greater than the potential at the negative input terminal of operational amplifier U5 formed by the voltage division of 2.5V reference voltage E0 by resistance R61 and resistance R62, operational amplifier U5 outputs a high potential, triode Q15 is turned on, the potential at the positive input terminal of operational amplifier U5A is pulled low through connection point X6, operational amplifier U5A outputs a low level, and the base of triode Q7 and triode Q8 is fed back through connection point X4, so that triode Q7 and triode Q8 work in PWM state, the on time of MOS tube Q3 is reduced, and the maximum value of excitation drive current is limited.

[0119] Drive tube short circuit protection unit 55 is connected to coil current monitoring unit 53 and AC / DC power supply module 1. When the supply current of contactor coil KM increases to be greater than the second set value due to the failure of the drive tube of coil driving unit 51 to limit its own output current, drive tube short circuit protection unit 55 generates a control signal to control contactor coil supply unit 14 in AC / DC power supply module 1 to cut off the power supply of contactor coil KM, thereby ensuring the safety of contactor coil KM and its associated devices.

[0120] A specific drive tube short circuit protection unit 55 includes a diode D34, a zener diode D33, a resistor R70, a resistor R65, a diode D32, a resistor R69, a capacitor C18, a voltage regulator integrated block U6, a resistor R67, a resistor R66, a triode Q17, a resistor R64, an optocoupler OT2, a thyristor Q2, a resistor R32 and a capacitor C8. The diode D34 and the zener diode D33 are connected in series between a connection point X8 and the ground, the resistor R70, the resistor R65 and the diode D32 are connected in series, one end of which is connected between the diode D34 and the zener diode D33, and the other end is connected to the collector of the triode Q17, the resistor R69 and the capacitor C18 are connected in parallel, one end of which is connected between the resistor R70 and the resistor R65, and the other end is connected to the ground. The voltage regulator integrated block U6 and the resistor R67 are connected in series between the base of the triode Q17 and the ground, the control end of the voltage regulator integrated block U6 is connected between the resistor R70 and the resistor R65, the emitter of the triode Q17 is connected to the power supply VCC, the resistor R66 is connected between the emitter and the base of the triode Q17, the collector of the triode Q17 is connected to the light emitting diode side of the optocoupler OT2 through the resistor R64, the output end collector of the optocoupler OT2 is connected to the anode of the thyristor Q2, the output end emitter of the optocoupler OT2 is connected to the control electrode of the thyristor Q2, the resistor R32 and the capacitor C8 are connected in parallel between the control electrode and the cathode of the thyristor Q2, the anode of the thyristor Q2 is connected to the connection point GATE1, the cathode is connected to the connection point HGND, and is connected to the corresponding connection point in the contactor coil power supply unit 14 through the connection point GATE1 and the connection point HGND.

[0121] If the drive tube in the coil driving unit 51 is broken, the contactor coil power supply output power VXG forms an uncontrolled large current through the contactor coil KM and the short-circuited drive tube Q3, which easily causes the contactor coil KM to be burned out under the long-time large current. After the drive tube is broken, the current in the contactor coil KM increases to a second set value higher than the first set value, the collector current of the triode QB further increases, the potential at the connection point X8 further increases, and the control end potential of the voltage stabilization integrated block U6 also increases. When the control end potential of the voltage stabilization integrated block U6 is greater than 2.5V, the voltage stabilization integrated block U6 is turned on, the triode Q17 is turned on, the collector current of the triode Q17 makes the optocoupler OT2 be turned on, the drive thyristor Q2 is turned on, the potential difference between the connection point GATE1 and the connection point HGND is close to zero, the MOS tube Q1 is turned off, and the contactor coil power supply output power VXG has no current output, thereby protecting the contactor coil KM and the related components in the current loop. In addition, the increase of the output current of the contactor coil power supply output power VXG also causes the resistance of the PTC resistor RF1 to increase, which can also protect the contactor coil KM. The parallel connection of the resistor R32 and the capacitor C8 between the control electrode and the cathode of the thyristor Q2 can prevent the false action of the thyristor Q2.

[0122] In a preferred embodiment of the AC-DC contactor control circuit of the present application, as shown in Figure 6 A fast turn-off unit 56 is further arranged in the drive output module 5. The fast turn-off unit 55 is connected between the voltage detection module 2 and the contactor coil KM, which can generate a demagnetization voltage after the external driving power is turned off, thereby improving the decay speed of the current in the contactor coil, and making the contactor quickly switch from the closed state to the open state.

[0123] A specific drive output module 5 includes resistance R92, optical coupler OT3, the first secondary coil TP1-NS1 of pulse transformer TP1, diode D17, resistance R37, capacitor CD5, voltage stabilizing diode D18, triode Q9, resistance R38, resistance R39, diode D19, resistance R40, resistance R41, MOS tube Q10, voltage stabilizing diode D20, resistance R43 and diode D21. The first secondary coil TP1-NS1 of pulse transformer TP1, diode D17 and resistance R37 are connected in series with each other, and capacitor CD5 and voltage stabilizing diode D18 are both connected in parallel across the series circuit. The input of optical coupler OT3 is connected between connection point X3 and ground through resistance R92, the collector of the output of optical coupler OT3 is connected to the negative pole of voltage stabilizing diode D18, the emitter is connected to the base of triode Q9, the positive pole of voltage stabilizing diode D18 is connected to the collector of triode Q9, resistance R38 is connected between the base and the collector of triode Q9, resistance R39 and diode D19 are connected in series between the base and the emitter of triode Q9, the emitter of triode Q9 is connected to the gate of MOS tube Q10 through resistance R40, resistance R41 is connected between the gate and the source of MOS tube Q10, voltage stabilizing diode D20 and resistance R43 are connected in series between the drain and the source of MOS tube Q10, the drain of MOS tube Q10 is connected to contactor coil KM, the source is connected to the collector of triode Q9 and is connected to contactor coil power supply output power VXG through diode D21.

[0124] In the electric holding mode, no matter in the excitation phase or in the closing holding phase, the potential at connection point X3 is high, optical coupler OT3 is turned on, and the electric pulse generated when the working power supply unit 16 works forms induced electromotive force in the first secondary coil TP1-NS2 of pulse transformer TP1, and after rectification by diode D17 and voltage stabilization by voltage stabilizing diode D18, a stable direct current voltage is formed on capacitor CD5, which acts between the base and the collector of triode Q9 and between the gate and the source of MOS tube Q10, triode Q9 is cut off, MOS tube Q10 is turned on, so that diode D21 is connected in parallel across contactor coil KM, without affecting the retention of the magnetic field in contactor coil KM.

[0125] When the AC / DC power supply module 1 is powered off, the potential at connection point X3 drops, optical coupler OT3 is cut off, triode Q9 is turned on, MOS tube Q10 is turned off, and the energy across contactor coil KM is released through the fast discharge circuit composed of voltage stabilizing diode D20, resistance R43 and diode D21. The length of the discharge time is related to the voltage stabilization value of voltage stabilizing diode D20, the larger the voltage stabilization value of voltage stabilizing diode D20, the larger the demagnetizing voltage acting on contactor coil KM, and the current in contactor coil KM decays very quickly, so that the contactor is quickly turned off, greatly reducing the opening time of the contactor.

[0126] One embodiment of the AC-DC contactor of the present application uses the AC-DC contactor control circuit of any embodiment of the present application, and has the advantages of the AC-DC contactor control circuit of the corresponding embodiment.

[0127] The voltage and current waveforms across the contactor coil KM during the magnetizing stage when the AC-DC contactor of one preferred embodiment of the present application is working at the DC rated voltage are shown in Fig. 2, from which it can be seen that the magnetizing drive current in the contactor coil KM rises rapidly after more than ten milliseconds after power-up, and rises to 3.115 A within 150 ms, so that the contactor is quickly closed. After the contactor is closed, the current in the contactor coil KM drops rapidly to a lower level, and switches to the closed-keep state. The voltage and current waveforms across the contactor coil KM during the closed-keep stage are shown in Fig. 3, from which it can be seen that the current in the contactor coil KM is maintained at a lower level during the closed-keep stage, and the square average of the closed-keep current is about 315 mA, so that the power consumption of the contactor coil KM is greatly reduced, effectively prolonging the service life of the contactor. Figure 7 Figure 8

[0128] The AC-DC contactor of the present application is used to work at the DC 80% rated voltage and 110% rated voltage power supply environment, as shown in Figs. 4 and 5, respectively. In the magnetizing stage, the maximum magnetizing current across the contactor coil KM obviously changes with the size of the power supply voltage, but the magnetizing speed and magnetizing time remain basically unchanged, and the contactor is quickly closed and then switches to the closed-keep state. In the closed-keep stage, as shown in Figs. 6 and 7, respectively, the closed-keep current in the contactor coil KM changes little and is stably maintained at about 310 mA, having obvious energy-saving and service life-prolonging effects. Figure 9 Figure 11 Figure 10 Figure 12

[0129] In the description of the present application, the description of the terms "one embodiment", "a specific embodiment", "a preferred embodiment" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. The illustrative description of the above terms in the present application does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0130] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application, so that: any equivalent changes made in accordance with the structure, shape, principle of the present application should be covered within the protection scope of the present application.​​​​​​

Claims

1. An AC / DC contactor control circuit, characterized in that: The system includes an AC / DC power supply module (1), a voltage detection module (2), an excitation control module (3), a closing sustaining module (4), and a drive output module (5). The AC / DC power supply module (1) includes an external drive power interface (11), which can be connected to an external drive power supply to convert the external drive power supply into a DC power supply for the drive control circuit. The voltage detection module (2) is connected to the external drive power interface (11), the excitation control module (3), and the closing sustaining module (4) to detect the AC / DC state of the external drive power supply and generate different trigger signals to control the excitation control module. (3) The working state of the closing maintenance module (4), the excitation control module (3) is connected to the closing maintenance module (4) and the drive output module (5) so as to generate an excitation control signal to control the drive output module (5) to generate an excitation drive current to drive the contactor to close, and control the working state of the closing maintenance module (4). The closing maintenance module (4) is connected to the drive output module (5) so as to generate a maintenance control signal to control the drive output module (5) to generate a closing holding current to maintain the contactor's closing state. The drive output module (5) is connected to the contactor coil so as to output a drive current to the contactor coil. The excitation control module (3) includes an excitation pulse forming unit (31), an excitation drive unit (32), and a holding mode control unit (33). The excitation pulse forming unit (31) is connected to the voltage detection module (2) so as to generate an excitation trigger pulse of a set width according to the state of the external drive power supply. The excitation drive unit (32) is connected between the excitation pulse forming unit (31) and the drive output module (5) so as to generate an excitation control signal corresponding to the excitation trigger pulse and control the drive output module (5) to generate an excitation drive current. The holding mode control unit (33) is connected between the excitation pulse forming unit (31) and the closing maintenance module (4) and the drive output module (5) so as to control the working state of the closing maintenance module (4) and the drive output module (5) after the excitation trigger pulse ends. The closing maintenance module (4) includes a PWM control unit (41) and a PWM suppression unit (42). The PWM control unit (41) is connected to the PWM suppression unit (42) and the drive output module (5) so that it can generate a PWM control signal under the control of the PWM suppression unit (42) to control the magnitude of the drive current generated by the drive output module (5). The PWM suppression unit (42) is connected to the holding mode control unit (33), the voltage detection module (2) and the PWM control unit (41) so that it can control the working state of the PWM control unit (41) according to the excitation mode of the contactor and the voltage state of the external drive power supply. The drive output module (5) includes a coil drive unit (51), which is connected to the excitation control module (3), the closing maintenance module (4) and the contactor coil, so as to output drive current to the contactor coil under the control of the excitation control signal and the maintenance control signal.

2. The AC / DC contactor control circuit according to claim 1, characterized in that: The AC / DC power supply module (1) includes an EMI protection unit (12), a rectifier unit (13), a contactor coil power supply unit (14), a fast power-up unit (15), a working power supply unit (16), a DC output unit (17), and a reference voltage unit (18). The EMI protection unit (12) is connected to the external drive power interface (11), and the rectifier unit (13) is connected to the EMI protection unit (12). The contactor coil power supply unit (14), the fast power-up unit (15), and the working power supply unit (16) are respectively connected to the output terminal of the rectifier unit (13). The electrical unit (14) can output power to drive the contactor to work. The fast power-up unit (15) can form the DC power required for the operation of the control circuit in advance. The working power unit (16) can form a regulated DC power supply to replace the fast power-up unit (15). The DC output unit (17) is connected to the fast power-up unit (15) and the working power unit (16) respectively, so as to output the DC power formed by the fast power-up unit (15) and the working power unit (16). The reference voltage unit (18) is connected to the DC output unit (17) so as to output a reference voltage of a set value.

3. The AC / DC contactor control circuit according to claim 2, characterized in that: The contactor coil power supply unit (14) includes a power supply protection subunit, an output control subunit, and a fuse. The power supply protection subunit is connected between the rectifier unit (13) and the output control subunit to provide overvoltage and overcurrent protection for the output control subunit. The output control subunit is connected to the working power supply unit (16) and the drive output module (5) to control the working state of the output control subunit according to the signals of the working power supply unit (16) and the drive output module (5). The fuse is connected to the output circuit of the output control subunit. The AC / DC power module (1) further includes a fast discharge unit (19), which is connected to the rectifier unit (13). The fast discharge unit (19) includes a fast discharge circuit and is able to output a fast discharge power supply connected to the fast discharge circuit.

4. The AC / DC contactor control circuit according to claim 2, characterized in that: The voltage detection module (2) includes an AC signal extraction unit (21) and an undervoltage protection unit (22). The AC signal extraction unit (21) is connected to the external drive power interface (11) to detect whether the external drive power is an AC power. The undervoltage protection unit (22) is connected to the AC signal extraction unit (21), the AC / DC power module (1), and the excitation control module (3) to output control signals according to the different AC / DC states and voltage values ​​of the external drive power, thereby controlling the working state of the excitation control module (3).

5. The AC / DC contactor control circuit according to claim 4, characterized in that: The voltage detection module (2) also includes an overvoltage protection unit (23), which is connected to the AC signal extraction unit (21), the reference voltage unit (18) and the closing maintenance module (4) so ​​that when the external drive power supply voltage exceeds the set range, the closing maintenance module (4) can be controlled to operate and cut off the output of the drive output module (5).

6. The AC / DC contactor control circuit according to claim 1, characterized in that: The closing maintenance module (4) also includes a feedback adjustment unit (43). The PWM control unit (41) is also connected to the feedback adjustment unit (43) so that it can generate a PWM control signal under the control of the feedback adjustment unit (43) to control the magnitude of the drive current generated by the drive output module (5). The feedback adjustment unit (43) is connected to the drive output module (5), the excitation pulse forming unit (31) and the PWM control unit (41) so that it can control the working state of the PWM control unit (41) according to the excitation trigger pulse and the drive current output by the drive output module (5), thereby controlling the magnitude of the drive current generated by the drive output module (5).

7. The AC / DC contactor control circuit according to claim 1, characterized in that: The drive output module (5) further includes a coil voltage feedback unit (52), a coil current monitoring unit (53), an excitation current limiting unit (54), and a drive tube short-circuit protection unit (55). The coil voltage feedback unit (52) and the coil current monitoring unit (53) are connected to the power supply circuit of the contactor coil and to the closing maintenance module (4) to generate feedback signals corresponding to the power supply voltage and current of the contactor coil, thereby adjusting the working state of the closing maintenance module (4). The excitation current limiting unit (54) is connected to the drive tube short-circuit protection unit (55). The coil drive unit (51) is connected to the excitation control module (3) so that when the output current of the coil drive unit (51) reaches the first set value, the working state of the excitation control module (3) can be controlled to control the maximum value of the output current of the coil drive unit (51). The drive tube short circuit protection unit (55) is connected to the coil current monitoring unit (53) and the AC / DC power supply module (1) so that when the power supply current of the contactor coil is greater than the second set value, the AC / DC power supply module (1) can be controlled to operate and cut off the power supply of the contactor coil.

8. The AC / DC contactor control circuit according to claim 7, characterized in that: The drive output module (5) also includes a fast shutdown unit (56), which is connected between the voltage detection module (2) and the contactor coil to generate a demagnetizing voltage when the external drive power supply is turned off, thereby increasing the decay rate of the current in the contactor coil.

9. An AC / DC contactor, characterized in that: The AC / DC contactor control circuit according to any one of claims 1-8 is used.

Images