Contactor and control method thereof

Abstract

The present disclosure relates to a contactor and a control method thereof capable of simplifying circuit design, optimizing hardware cost, and reducing electromagnetic interference noise. The contactor comprises a contactor coil, a rectifier filter unit, a flyback switching power supply, a control unit, a first switch tube, a first diode, a second diode, and a current sampling unit. The control unit is configured to control the on-off of the first switch tube and the second switch tube, wherein, in the attraction stage, the on-off duty cycle of the first switch tube is adjusted according to the current detected by the current sampling unit to achieve stable attraction current, and in the holding stage, the on-off duty cycle of the second switch tube is adjusted according to the current detected by the current sampling unit to achieve stable holding current.

Description

Technical Field

[0001] This disclosure relates to contactors and control methods thereof, and more particularly to contactors and control methods thereof using flyback switching power supplies. Background Technology

[0002] In existing contactors, a flyback switching power supply is used to power the various components, and a control unit is used to control the contactor coil's engagement and engagement.

[0003] However, in existing technologies, circuit design is relatively complex, and electromagnetic interference (EMI) noise has a significant impact. Summary of the Invention

[0004] In view of the above, this disclosure provides a contactor and its control method that can simplify circuit design, optimize hardware costs, and reduce EMI noise.

[0005] According to one aspect of this disclosure, a contactor is provided, the contactor including a contactor coil, a rectifier and filter unit, a flyback switching power supply, a control unit, a first switching transistor (T1), a first diode (D1), a second diode (D2), a fourth switching transistor (T4), and a current sampling unit; the rectifier and filter unit is used to convert input alternating current into direct current having a first voltage; the flyback switching power supply is connected to the voltage output terminal of the rectifier and filter unit for converting the first voltage, the flyback switching power supply including a transformer, a second switching transistor (T2), and a flyback controller, the first terminal of the series circuit formed by the second switching transistor (T2) and the primary coil of the transformer serves as the voltage input terminal of the flyback switching power supply and is connected to the voltage output terminal of the rectifier and filter unit, the second terminal of the series circuit formed by the second switching transistor (T2) and the primary coil is connected to ground; the first terminal of the contactor coil is connected to the output terminal of the rectifier and filter unit through the first switching transistor (T1) to receive the pull-in current, and through the second diode (D2)... A fourth switch (T4) is connected to the first output terminal of the flyback power supply to receive the holding current. The first output terminal of the flyback power supply outputs a second voltage. The second terminal of the contactor coil is connected to ground. The anode of the second diode (D2) is connected to the first output terminal of the flyback power supply, and the cathode of the second diode (D2) is connected to the first terminal of the contactor coil. The first diode (D1) is used as a freewheeling diode. The cathode of the first diode (D1) is connected to the first terminal of the contactor coil, and the anode of the first diode (D1) is connected to ground. The current sampling unit is used to detect the current in the contactor coil. The control unit is used to control the switching on and off of the first switch (T1) and the fourth switch (T4). During the pull-in phase, the duty cycle of the first switch (T1) is adjusted according to the current detected by the current sampling unit to achieve a stable pull-in current. During the holding phase, the duty cycle of the fourth switch (T4) is adjusted according to the current detected by the current sampling unit to achieve a stable holding current.

[0006] Optionally, it also includes a third switching transistor (T3) connected in series with the contactor coil, which is controlled by the control unit to cut off when the contactor should disconnect the contacts.

[0007] Optionally, the control unit is connected to the first switch (T1) via a first drive circuit, to the second switch (T2) via a second drive circuit, and / or to the third switch (T3) via a third drive circuit; the first drive circuit, the second drive circuit, and / or the third drive circuit are powered by the voltage output by the flyback power supply; and the flyback controller, during the pull-in phase, controls the on / off duty cycle of the second switch (T2) based on the voltage output by the flyback power supply to stabilize the voltage output by the flyback power supply.

[0008] Optionally, the second switching transistor (T2) is connected between the primary coil and the ground wire; the third switching transistor (T3) is connected between the contactor coil and the ground wire; the second driving circuit and the third driving circuit are powered by a second voltage output from the first output terminal of the flyback switching power supply; the flyback switching power supply includes a second output terminal that outputs a third voltage for powering the first driving circuit.

[0009] Optionally, the flyback switching power supply includes a second output terminal that outputs a third voltage for powering the first drive circuit; and the flyback switching power supply includes a third output terminal that outputs a fourth voltage for powering the second drive circuit and the third drive circuit.

[0010] Optionally, it also includes: a filter connected between the voltage output terminal of the rectifier filter unit and the voltage input terminal of the flyback switching power supply, for filtering out electromagnetic interference.

[0011] Optionally, the voltage output terminal of the rectifier and filter unit is connected to the control unit. The control unit determines whether the contactor should be disconnected based on the output voltage of the rectifier and filter unit. If it is determined that the contactor should be disconnected, the control unit controls the third switch (T3) to be turned off.

[0012] According to another aspect of the present disclosure, a contactor is provided, the contactor including a contactor coil, a rectifier filter unit, a flyback switching power supply, a control unit, a first switching transistor (T1), a first diode (D1), a second diode (D2), and a current sampling unit; the rectifier filter unit is used to convert input AC power into DC power with a first voltage; the flyback switching power supply is connected to the voltage output terminal of the rectifier filter unit for converting the first voltage, the flyback switching power supply includes a transformer and a second switching transistor (T2), the first end of the series circuit formed by the second switching transistor (T2) and the primary coil of the transformer serves as the voltage input terminal of the flyback switching power supply and is connected to the voltage output terminal of the rectifier filter unit, the second end of the series circuit formed by the second switching transistor (T2) and the primary coil is connected to ground; the first end of the contactor coil is connected to the output terminal of the rectifier filter unit through the first switching transistor (T1) to receive the pull-in current, and is connected to the current sampling unit through the second diode (D2). The first output terminal of the flyback switching power supply is connected to receive the holding current, and the first output terminal of the flyback switching power supply outputs a second voltage. The second terminal of the contactor coil is connected to ground. The anode of the second diode (D2) is connected to the first output terminal of the flyback switching power supply, and the cathode of the second diode (D2) is connected to the first terminal of the contactor coil. The first diode (D1) is used as a freewheeling diode, and the cathode of the first diode (D1) is connected to the first terminal of the contactor coil. The anode of the first diode (D1) is connected to ground. The current sampling unit is used to detect the current in the contactor coil. The control unit is used to control the switching on and off of the first switch (T1) and the second switch (T2). During the pull-in phase, the duty cycle of the first switch (T1) is adjusted according to the current detected by the current sampling unit to achieve a stable pull-in current. During the holding phase, the duty cycle of the second switch (T2) is adjusted according to the current detected by the current sampling unit to achieve a stable holding current.

[0013] Optionally, it also includes a third switching transistor (T3) connected in series with the contactor coil, which is controlled by the control unit to cut off when the contactor should disconnect the contacts.

[0014] Optionally, the control unit is connected to the first switching transistor (T1) via a first driving circuit, to the second switching transistor (T2) via a second driving circuit, and / or to the third switching transistor (T3) via a third driving circuit; the first driving circuit, the second driving circuit, and / or the third driving circuit are powered by the voltage output by the flyback switching power supply; and during the pull-in phase, the control unit controls the on / off duty cycle of the second switching transistor (T2) based on the voltage output by the flyback switching power supply to stabilize the voltage output by the flyback switching power supply.

[0015] Optionally, the second switching transistor (T2) is connected between the primary coil and the ground wire; the third switching transistor (T3) is connected between the contactor coil and the ground wire; the second driving circuit and the third driving circuit are powered by a second voltage output from the first output terminal of the flyback switching power supply; the flyback switching power supply includes a second output terminal that outputs a third voltage for powering the first driving circuit.

[0016] Optionally, the flyback switching power supply includes a second output terminal that outputs a third voltage for powering the first drive circuit; and the flyback switching power supply includes a third output terminal that outputs a fourth voltage for powering the second drive circuit and the third drive circuit.

[0017] Optionally, it also includes: a filter connected between the voltage output terminal of the rectifier filter unit and the voltage input terminal of the flyback switching power supply, for filtering out electromagnetic interference.

[0018] Optionally, the voltage output terminal of the rectifier and filter unit is connected to the control unit. The control unit determines whether the contactor should be disconnected based on the output voltage of the rectifier and filter unit. If it is determined that the contactor should be disconnected, the control unit controls the third switch (T3) to be turned off.

[0019] According to another aspect of the present disclosure, a control method for a contactor is provided, wherein an input alternating current is converted into direct current having a first voltage by a rectifier and filter unit; the first voltage is converted into a second voltage by a flyback switching power supply, the flyback switching power supply including a second switching transistor (T2) connected in series with its primary coil for controlling the output of the flyback switching power supply; in the pull-in phase, the contactor coil is connected to the first voltage through a first switching transistor (T1) to receive a pull-in current, and a stable pull-in current is achieved by adjusting the on / off duty cycle of the first switching transistor (T1) by detecting the current in the contactor coil; in the holding phase, the contactor coil is connected to the second voltage through a second diode (D2) to receive a holding current, and a stable holding current is achieved by adjusting the on / off duty cycle of the second switching transistor (T2) by detecting the current in the contactor coil.

[0020] Optionally, the contactor coil is connected in series with a third switch (T3); the control method further includes turning off the third switch (T3) when the contactor should disconnect the contacts.

[0021] Optionally, the first switch (T1), the second switch (T2), and the third switch (T3) each have a first driving circuit, a second driving circuit, and a third driving circuit, respectively; the first driving circuit, the second driving circuit, and / or the third driving circuit are powered by the voltage output by the flyback power supply; and the control method further includes: during the pull-in phase, controlling the on / off duty cycle of the second switch (T2) based on the voltage output by the flyback power supply to stabilize the voltage output by the flyback power supply.

[0022] Optionally, a filter is provided between the output terminal of the rectifier filter unit and the input terminal of the flyback switching power supply to filter out electromagnetic interference.

[0023] Optionally, the control method further includes: determining whether the contactor should disconnect its contacts based on the output voltage of the rectifier filter unit, and controlling the third switch (T3) to turn off if it is determined that the contactor should disconnect its contacts.

[0024] According to embodiments of this disclosure, circuit design can be simplified, hardware costs optimized, and electromagnetic interference noise reduced. Attached Figure Description

[0025] These and / or other aspects, features, and advantages of this disclosure will become clearer and more readily understood from the following description of embodiments in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 This is a schematic diagram of an example structure of a contactor according to the first embodiment of this disclosure.

[0027] Figure 2 This is a schematic diagram of an example structure of a contactor according to a second embodiment of the present disclosure.

[0028] Figure 3 This is an example schematic diagram illustrating the signal flow direction of the contactor during the engagement phase according to the second embodiment of this disclosure.

[0029] Figure 4 This is an example schematic diagram illustrating the signal flow of the contactor during the holding phase according to the second embodiment of this disclosure.

[0030] Figure 5 This is another example structural schematic diagram of the contactor involved in the second embodiment of this disclosure.

[0031] Figure 6 This is a flowchart of a contactor control method according to the second embodiment of this disclosure. Detailed Implementation

[0032] The present disclosure will now be described in detail with reference to exemplary embodiments thereof. However, the present disclosure is not limited to the embodiments described herein, which may be implemented in many different forms. The described embodiments are provided only to make the present disclosure thorough and complete, and to fully convey the concept of the present disclosure to those skilled in the art. Features of the various embodiments described may be combined with or substituted for each other, unless expressly excluded or should be excluded based on the context.

[0033] In existing contactors, a flyback switching power supply is used to power the various components, and a control unit is used to control the contactor coil's engagement and engagement.

[0034] In order to better control the engagement and holding of the contactor coil, the following scheme is proposed in this disclosure.

[0035] This disclosure provides an embodiment of a contactor, which includes a contactor coil, a rectifier and filter unit, a flyback switching power supply, a control unit, a first switching transistor (T1), a first diode (D1), a second diode (D2), a fourth switching transistor (T4), and a current sampling unit. The rectifier and filter unit converts input AC power into DC power with a first voltage. The flyback switching power supply is connected to the voltage output terminal of the rectifier and filter unit to convert the first voltage. The flyback switching power supply includes a transformer, a second switching transistor (T2), and a flyback controller. The first terminal of the series circuit formed by the second switching transistor (T2) and the primary coil of the transformer serves as the voltage input terminal of the flyback switching power supply and is connected to the voltage output terminal of the rectifier and filter unit. The second terminal of the series circuit formed by the second switching transistor (T2) and the primary coil is connected to ground. The first terminal of the contactor coil is connected to the output terminal of the rectifier and filter unit through the first switching transistor (T1) to receive the pull-in current, and is connected through the second diode (D2) and the fourth switching transistor (T4) to receive the pull-in current. A switching transistor (T4) is connected to the first output terminal of the flyback switching power supply to receive the holding current. The first output terminal of the flyback switching power supply outputs a second voltage. The second terminal of the contactor coil is connected to ground. The anode of the second diode (D2) is connected to the first output terminal of the flyback switching power supply, and the cathode of the second diode (D2) is connected to the first terminal of the contactor coil. The first diode (D1) is used as a freewheeling diode. The cathode of the first diode (D1) is connected to the first terminal of the contactor coil, and the anode of the first diode (D1) is connected to ground. The current sampling unit is used to detect the current in the contactor coil. The control unit is used to control the switching on and off of the first switching transistor (T1) and the fourth switching transistor (T4). During the pull-in phase, the duty cycle of the first switching transistor (T1) is adjusted according to the current detected by the current sampling unit to achieve a stable pull-in current. During the holding phase, the duty cycle of the fourth switching transistor (T4) is adjusted according to the current detected by the current sampling unit to achieve a stable holding current.

[0036] Embodiments of this disclosure also provide a contactor, which includes a contactor coil, a rectifier and filter unit, a flyback switching power supply, a control unit, a first switching transistor (T1), a first diode (D1), a second diode (D2), and a current sampling unit. The rectifier and filter unit converts input AC power into DC power with a first voltage. The flyback switching power supply is connected to the voltage output terminal of the rectifier and filter unit to convert the first voltage. The flyback switching power supply includes a transformer and a second switching transistor (T2). The first terminal of the series circuit formed by the second switching transistor (T2) and the primary coil of the transformer serves as the voltage input terminal of the flyback switching power supply and is connected to the voltage output terminal of the rectifier and filter unit. The second terminal of the series circuit formed by the second switching transistor (T2) and the primary coil is connected to ground. The first terminal of the contactor coil is connected to the output terminal of the rectifier and filter unit through the first switching transistor (T1) to receive the pull-in current, and is connected to the flyback switching power supply through the second diode (D2). The first output terminal of the switching power supply is connected to receive the holding current. The first output terminal of the flyback switching power supply outputs a second voltage. The second terminal of the contactor coil is connected to ground. The anode of the second diode (D2) is connected to the first output terminal of the flyback switching power supply, and the cathode of the second diode (D2) is connected to the first terminal of the contactor coil. The first diode (D1) is used as a freewheeling diode. The cathode of the first diode (D1) is connected to the first terminal of the contactor coil, and the anode of the first diode (D1) is connected to ground. The current sampling unit is used to detect the current in the contactor coil. The control unit is used to control the switching on and off of the first switch (T1) and the second switch (T2). During the pull-in phase, the duty cycle of the first switch (T1) is adjusted according to the current detected by the current sampling unit to achieve a stable pull-in current. During the holding phase, the duty cycle of the second switch (T2) is adjusted according to the current detected by the current sampling unit to achieve a stable holding current.

[0037] Figure 1 This is a schematic diagram of an example structure of a contactor according to the first embodiment of this disclosure.

[0038] like Figure 1 As shown, the contactor 100 includes a rectifier and filter unit 101, a flyback switching power supply 102, a control unit 103, a contactor coil 104, a switching transistor T1, a diode D1, a diode D2, a switching transistor T4, and a current sampling unit 105.

[0039] The rectifier and filter unit 101 receives the AC power output from the power supply and performs rectification and filtering to convert it into DC power with voltage VCO. The power supply can be any AC power source.

[0040] The flyback switching power supply (also known as a flyback power supply, flyback power source, or switching power supply) 102 may include a transformer 1021, a switching transistor T2, and a flyback controller (also known as a flyback power supply chip or flyback control chip) 1022. A DC current with voltage VCO is input to the flyback switching power supply 102. Through the transformer 1021 of the flyback switching power supply 102, voltage VCO is converted to voltage VC1 and output via the output terminal of the flyback switching power supply 102.

[0041] The contactor coil 104 is used to control the contact state of the contactor 100 during the inrush and holding phases. One end of the contactor coil 104 is connected to the output of the rectifier filter unit 101 via the switching transistor T1 to receive the inrush current, and is connected to the output of the flyback switching power supply 102 via the diode D2 and the switching transistor T4 to receive the holding current. The other end of the contactor coil 104 is connected to ground.

[0042] The anode of diode D2 is connected to the switching transistor T4, and the cathode of diode D2 is connected to one end of the contactor coil 104. The positions of switching transistor T4 and diode D2 can also be interchanged. Diode D2 is used to prevent a short circuit between voltage VC0 and voltage VC1 of the flyback switching power supply 102 during the pull-in phase.

[0043] Diode D1 is used as a freewheeling diode to provide a freewheeling path for the coil current when switching transistors T1 and T4 are off. The cathode of diode D1 is connected to one end of contactor coil 104, and the anode of diode D1 is connected to ground.

[0044] The control unit 103 is used to control the on / off state of switch T1 and switch T4.

[0045] During the pull-in phase, the control unit 103 controls the switch T4 to turn off. At this time, the voltage VC1 output by the flyback switching power supply 102 is not connected to the contactor coil 104, while the voltage VCO output by the rectifier and filter unit 101 is connected to the contactor coil 104 through the switch T1. During the pull-in phase, the control unit 103 adjusts the on / off duty cycle of the switch T1 according to the current through the contactor coil 104 detected by the current sampling unit 105 to achieve a stable pull-in current.

[0046] During the holding phase, the control unit 103 controls the switch T1 to be turned off. At this time, the voltage VCO output by the rectifier filter unit 101 is not connected to the contactor coil 104, while the voltage VC1 output by the flyback switching power supply 102 is connected to the contactor coil 104 through the switch T4. During the holding phase, the control unit 103 adjusts the on / off duty cycle of the switch T4 according to the current through the contactor coil 104 detected by the current sampling unit 105 to achieve a stable holding current.

[0047] Furthermore, the flyback controller 1022 can control the on / off duty cycle of the switching transistor T2 based on the voltage feedback from the flyback switching power supply 102, thereby stabilizing the output voltage of the flyback switching power supply 102. It should be noted that the output voltage of the flyback switching power supply 102 includes voltage VC1, and may also include voltages output from other secondary coils of the flyback switching power supply 102, such as voltages used to power other components.

[0048] Each switch can have its own drive circuit, which can be an independent drive circuit or a drive circuit integrated into the control unit 103 or integrated inside each switch.

[0049] Each switching transistor can be a suitable semiconductor switching transistor, such as an IGBT or a MOSFET. For example, if each switching transistor is a MOSFET, the drain of switching transistor T1 can be connected to the output terminal of the rectifier filter unit 101, the source of switching transistor T1 can be connected to one end of the contactor coil 104, and the gate of switching transistor T1 can be connected to the control unit 103 or the driving circuit of switching transistor T1; the drain of switching transistor T2 can be connected to the primary coil of transformer 1021, the source of switching transistor T2 can be connected to ground, and the gate of switching transistor T2 can be connected to the flyback controller 1022 or the driving circuit of switching transistor T2; the drain of switching transistor T4 can be connected to the anode of diode D2, the source of switching transistor T4 can be connected to the output terminal of the flyback switching power supply 102, and the gate of switching transistor T4 can be connected to the control unit 103 or the driving circuit of switching transistor T4.

[0050] In this embodiment, the switching transistor T4 needs to have its on / off duty cycle adjusted during the holding phase, thus exhibiting significant voltage variation (dV / dt) and current variation (dI / dt) over time. The output of the flyback power supply does not directly drive the contactor coil but passes through the switching transistor T4, making it one of the main sources of electromagnetic interference (EMI). The switching duty cycle can be adjusted using pulse width modulation (PWM), particularly high-frequency PWM. However, this further increases EMI noise.

[0051] To address EMI, additional components are needed, leading to a more complex circuit architecture and increased hardware costs.

[0052] To simplify circuit design, this disclosure proposes a method for directly controlling the switching transistor T2 in a flyback power supply using a control unit. Compared to the architecture of the first embodiment, this method effectively simplifies circuit design, optimizes hardware costs, and reduces EMI noise.

[0053] In the architecture of the first embodiment, control unit 103 is used to control the on / off duty cycles of switching transistors T1 and T4 to stabilize the current of contactor coil 104, and flyback controller 1022 is used to control the on / off duty cycle of switching transistor T2 to stabilize the output voltage of flyback switching power supply 102. Since the two are independent of each other, the overall integration of the solution is low. In practice, the flyback switching power supply and the contactor coil can be integrated into a single control core and controlled uniformly by the control unit.

[0054] Figure 2 This is a schematic diagram of an example structure of a contactor according to a second embodiment of the present disclosure.

[0055] In the second embodiment, the contactor 200 may include a rectifier and filter unit 201, a flyback switching power supply 202, a control unit 203, a contactor coil 204, a switching transistor T1, a diode D1, a diode D2, and a current sampling unit 205.

[0056] The rectifier and filter unit 201 receives the AC power output from the power supply and performs rectification and filtering to convert the AC power into DC power with voltage VCO. The power supply can be any AC power source.

[0057] The flyback switching power supply 202 may include a transformer 2021 and a switching transistor T2. A DC current with voltage VCO is input to the flyback switching power supply 202. Through the transformer 2021 of the flyback switching power supply 202, the voltage VCO is converted into voltage VC1 and output through the output terminal of the flyback switching power supply 202.

[0058] The contactor coil 204 is used to control the contact state of the contactor 200 during the pull-in and holding phases. One end of the contactor coil 204 is connected to the output of the rectifier filter unit 201 through the switching transistor T1 to receive the pull-in current, and is connected to the output of the flyback switching power supply 202 through the diode D2 to receive the holding current. The other end of the contactor coil 204 is connected to the ground wire.

[0059] The anode of diode D2 is connected to the output terminal of flyback switching power supply 202, and the cathode of diode D2 is connected to one end of contactor coil 204. Diode D2 is used to prevent a short circuit between voltage VC0 and voltage VC1 of flyback switching power supply 102 during the pull-in phase.

[0060] Diode D1 is used as a freewheeling diode to provide a freewheeling path for the coil current when the switching transistor T1 is turned off. The cathode of diode D1 is connected to one end of the contactor coil 204, and the anode of diode D1 is connected to ground.

[0061] The control unit 203 is used to control the on / off state of switch T1 and switch T2.

[0062] Each switch can have its own drive circuit, which can be an independent drive circuit or a drive circuit integrated into the control unit 103 or integrated inside each switch.

[0063] Each switching transistor can be a suitable semiconductor switching transistor, such as an IGBT or a MOSFET. For example, if each switching transistor is a MOSFET, the drain of switching transistor T1 can be connected to the output terminal of the rectifier filter unit 201, the source of switching transistor T1 can be connected to one end of the contactor coil 204, and the gate of switching transistor T1 can be connected to the control unit 203 or the drive circuit; the drain of switching transistor T2 can be connected to the primary coil of the transformer 2021, the source of switching transistor T2 can be connected to the ground wire, and the gate of switching transistor T2 can be connected to the control unit 203 or the drive circuit.

[0064] Figure 3 This is an example schematic diagram illustrating the signal flow direction of the contactor during the engagement phase according to the second embodiment of this disclosure.

[0065] During the pull-in phase, under normal circumstances, the voltage VC1 output by the flyback switching power supply 202 is lower than the voltage VC0 output by the rectifier filter unit 201. At this time, diode D2 is cut off, and only the voltage VC0 output by the rectifier filter unit 201 is connected to the contactor coil 204. During the pull-in phase, the control unit 203 adjusts the on / off duty cycle of the switching transistor T1 based on the current through the contactor coil 204 detected by the current sampling unit 205 to achieve a stable pull-in current.

[0066] Furthermore, during the pull-in phase, the control unit 203 can also control the on / off duty cycle of the switching transistor T2 based on the voltage feedback from the flyback power supply 202, thereby stabilizing the output voltage of the flyback power supply 202. It should be noted that the output voltage of the flyback power supply 202 includes voltage VC1, and may also include voltages output from other secondary coils of the flyback power supply 202, such as voltages used to power other components, like... Figure 5 The voltages VC2 and VC3 in the middle.

[0067] Figure 4 This is an example schematic diagram illustrating the signal flow of the contactor during the holding phase according to the second embodiment of this disclosure.

[0068] During the holding phase, the control unit 203 controls the switch T1 to be turned off. At this time, the voltage VCO output by the rectifier filter unit 201 is not connected to the contactor coil 204, while the voltage VC1 output by the flyback switching power supply 202 is connected to the contactor coil 204. During the holding phase, the control unit 203 adjusts the on / off duty cycle of the switch T2 according to the current through the contactor coil 204 detected by the current sampling unit 205 to achieve a stable holding current.

[0069] In the contactor of the second embodiment, during the holding phase, the voltage VC1 output by the flyback switching power supply 202 directly drives the coil through the diode D2, eliminating the need for the switching transistor T4 in the first embodiment. As a result, the EMI noise source is located only in the flyback switching power supply section, reducing the number of components with large dV / dt or dI / dt in the circuit and reducing the EMI noise source.

[0070] Diode D1 provides a freewheeling path for the coil current only during the pull-in phase when the switch T1 is off. During the holding phase, the contactor coil is powered by DC VC1, and diode D1 is in the off state, so there is no current variation (dI / dt) over time, thus reducing EMI noise.

[0071] Furthermore, since the flyback controller, switching transistor T4, and their driving circuit of the first embodiment are not required, the complexity and cost of the circuit architecture can be greatly optimized.

[0072] Figure 5 This is another example structural schematic diagram of the contactor involved in the second embodiment of this disclosure.

[0073] like Figure 5 As shown, the contactor 200 may also include a switching transistor T3 connected in series with the contactor coil 204. The switching transistor T3 is normally in the on state during operation. When the contactor 200 should disconnect the contacts, the control unit 203 controls the switching transistor T3 to turn off, thereby quickly de-energizing the contactor coil 204.

[0074] The switching transistor T3 can also be an IGBT, a MOSFET, or similar device. For example, if the switching transistor T3 is a MOSFET, its drain can be connected to the other end of the contactor coil 204, its source can be connected to ground, and its gate can be connected to the control unit 203 or the drive circuit.

[0075] Switch T1 can have an external drive circuit 207, switch T2 can have an external drive circuit 208, and switch T3 can have an external drive circuit 209. Control unit 203 can be connected to switch T1 via drive circuit 207, to switch T2 via drive circuit 208, and to switch T3 via drive circuit 209 to control each switch. Drive circuits 207, 208, and 209 can also be powered by the voltage output from flyback power supply 202.

[0076] For example, switching transistor T2 can be connected between the primary coil of transformer 2021 in flyback switching power supply 202 and ground, and switching transistor T3 can be connected between the other end of contactor coil 204 and ground. The secondary winding of flyback switching power supply 202 can also have an auxiliary winding to convert voltage VCO to voltage VC2. In this case, the drive circuit 208 of switching transistor T2 and the drive circuit 209 of switching transistor T3 can be powered by the voltage VC1 output from flyback switching power supply 202, and the drive circuit 207 of switching transistor T1 can be powered by the voltage VC2 output from flyback switching power supply 202.

[0077] The secondary winding of the flyback switching power supply 202 may also have an auxiliary winding that converts voltage VCO into voltage VC3. The drive circuit 208 of the switching transistor T2 and the drive circuit 209 of the switching transistor T3 may be powered by the voltage VC3 output by the flyback switching power supply, or by the voltages VC1 and VC3 output by the flyback switching power supply 202. The drive circuit 207 of the switching transistor T1 may be powered by the voltage VC2 output by the flyback switching power supply 202.

[0078] The voltages VC1, VC2 and / or VC3 output by the flyback switching power supply 202 can also power components such as the control unit 203.

[0079] Furthermore, a filter 206 for filtering out electromagnetic interference can be connected between the voltage output terminal of the rectifier filter unit 201 and the voltage input terminal of the flyback switching power supply 202. The filter 206 can be, for example, a low-pass CLC filter.

[0080] Furthermore, the voltage output terminal of the rectifier-filter unit 201 can be connected to the control unit 203, so that the control unit 203 determines whether the contactor 200 should open its contacts based on the output voltage of the rectifier-filter unit 201. If it determines that the contacts should be opened, it controls the switch T3 to turn off. For example, if the voltage at the voltage output terminal of the rectifier-filter unit 201 is detected to be lower than the rated value for a certain period of time, it is determined that the contactor should open its contacts, thereby turning off the switch T3.

[0081] The control unit 203 may be, for example, a microcontroller (MCU).

[0082] The above combination Figure 5 The description of the second embodiment also applies to the first embodiment without conflict.

[0083] Figure 6 This is a flowchart of a contactor control method according to the second embodiment of this disclosure.

[0084] like Figure 6 As shown, in the control method of the contactor,

[0085] The input AC power is converted into DC power with voltage VCO by the rectifier and filter unit 201 (step S1);

[0086] The voltage VCO is converted to voltage VC1 by the flyback switching power supply 202 (step S2);

[0087] During the pull-in phase, the contactor coil 204 receives the pull-in current by connecting the voltage VCO through the switching transistor T1, and the on / off duty cycle of the switching transistor T1 is adjusted by detecting the current in the contactor coil 204 to achieve a stable pull-in current S2 (step S3).

[0088] During the holding phase, the contactor coil 204 is connected to voltage VC1 through diode D2 to receive the holding current, and the on / off duty cycle of the switch transistor T2 is adjusted by detecting the current in the contactor coil 204 to achieve a stable holding current S3 (step S4).

[0089] The above description of the contactor in the second embodiment also applies to... Figure 6 The control methods will not be elaborated here.

[0090] For example, the contactor coil is connected in series with a third switch; the control method further includes turning off the third switch when the contactor should disconnect the contacts.

[0091] For example, the first switch, the second switch, and the third switch each have a first driving circuit, a second driving circuit, and a third driving circuit, respectively; the first driving circuit, the second driving circuit, and / or the third driving circuit are powered by the voltage output by the flyback power supply; and the control method further includes: during the pull-in phase, controlling the on / off duty cycle of the second switch based on the voltage output by the flyback power supply to stabilize the voltage output by the flyback power supply.

[0092] For example, a filter is provided between the output of the rectifier filter unit and the input of the flyback switching power supply to filter out electromagnetic interference.

[0093] For example, the control method further includes: determining whether the contactor should disconnect its contacts based on the output voltage of the rectifier filter unit, and controlling the third switch to turn off if it is determined that the contactor should disconnect its contacts.

[0094] Where there is no conflict, each unit in this disclosure can be separated into multiple sub-units, multiple units can be combined into one unit, the parallel and inclusion relationships between units can be changed, and the order of each method step can be changed.

[0095] The block diagrams of circuits, devices, apparatuses, equipment, and systems disclosed herein are merely illustrative examples and are not intended to require or imply that connections, arrangements, or configurations must be made in the manner shown in the block diagrams. As those skilled in the art will recognize, these circuits, devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner that achieves the desired purpose.

[0096] Those skilled in the art should understand that the specific embodiments described above are merely examples and not limitations. Various modifications, combinations, partial combinations, and substitutions can be made to the embodiments of this disclosure according to design requirements and other factors, as long as they are within the scope of the appended claims or their equivalents, and thus fall within the scope of the rights to be protected by this disclosure.

Claims

1. A contactor, characterized in that, The contactor includes a contactor coil, a rectifier and filter unit, a flyback switching power supply, a control unit, a first switching transistor, a first diode, a second diode, and a current sampling unit; The rectifier and filter unit is used to convert the input alternating current into direct current with a first voltage; The flyback switching power supply is connected to the voltage output terminal of the rectifier filter unit to convert the first voltage. The flyback switching power supply includes a transformer and a second switching transistor. The first end of the series circuit formed by the second switching transistor and the primary coil of the transformer serves as the voltage input terminal of the flyback switching power supply and is connected to the voltage output terminal of the rectifier filter unit. The second end of the series circuit formed by the second switching transistor and the primary coil is connected to the ground wire. The first end of the contactor coil is connected to the output end of the rectifier filter unit through the first switching transistor to receive the pull-in current, and is connected to the first output end of the flyback switching power supply through the second diode to receive the holding current. The first output end of the flyback switching power supply outputs a second voltage, and the second end of the contactor coil is connected to the ground wire. The anode of the second diode is connected to the first output terminal of the flyback switching power supply, and the cathode of the second diode is connected to the first terminal of the contactor coil. The first diode is used as a freewheeling diode, the cathode of the first diode is connected to the first end of the contactor coil, and the anode of the first diode is connected to the ground wire; The current sampling unit is used to detect the current in the contactor coil; The control unit is used to control the on / off state of the first switch and the second switch. During the pull-in phase, the duty cycle of the first switch is adjusted according to the current detected by the current sampling unit to achieve a stable pull-in current. During the holding phase, the duty cycle of the second switch is adjusted according to the current detected by the current sampling unit to achieve a stable holding current.

2. The contactor as claimed in claim 1, characterized in that, Also includes: The third switching transistor, connected in series with the contactor coil, is controlled by the control unit to cut off when the contactor should disconnect its contacts.

3. The contactor as described in claim 2, characterized in that, The control unit is connected to the first switching transistor via a first driving circuit, to the second switching transistor via a second driving circuit, and / or to the third switching transistor via a third driving circuit; The first drive circuit, the second drive circuit, and / or the third drive circuit are powered by the voltage output from the flyback switching power supply; and During the pull-in phase, the control unit controls the on / off duty cycle of the second switching transistor based on the voltage output of the flyback power supply to stabilize the voltage output of the flyback power supply.

4. The contactor as described in claim 3, characterized in that, The second switching transistor is connected between the primary coil and the ground wire; The third switch is connected between the contactor coil and the ground wire; The second drive circuit and the third drive circuit are powered by the second voltage output from the first output terminal of the flyback switching power supply; The flyback switching power supply includes a second output terminal that outputs a third voltage for supplying power to the first drive circuit.

5. The contactor as described in claim 3, characterized in that, The flyback switching power supply includes a second output terminal that outputs a third voltage, used to power the first drive circuit. as well as The flyback switching power supply includes a third output terminal that outputs a fourth voltage, used to power the second drive circuit and the third drive circuit.

6. The contactor as described in any one of claims 1 to 5, characterized in that, Also includes: A filter is connected between the voltage output terminal of the rectifier filter unit and the voltage input terminal of the flyback switching power supply to filter out electromagnetic interference.

7. The contactor as described in any one of claims 2 to 5, characterized in that, The voltage output terminal of the rectifier and filter unit is connected to the control unit. The control unit determines whether the contactor should be disconnected based on the output voltage of the rectifier filter unit. If it determines that the contactor should be disconnected, it controls the third switch to turn off.

8. A control method for a contactor, characterized in that, Applied to the contactor according to claim 1, the method includes: The input AC power is converted into DC power with a first voltage through a rectifier and filter unit; The first voltage is converted into a second voltage by a flyback switching power supply, the flyback switching power supply including a second switching transistor connected in series with its primary coil for controlling the output of the flyback switching power supply; During the pull-in phase, the contactor coil is connected to the first voltage through the first switching transistor to receive the pull-in current, and the on / off duty cycle of the first switching transistor is adjusted by detecting the current in the contactor coil to achieve a stable pull-in current. During the holding phase, the contactor coil is connected to the second voltage through the second diode to receive the holding current, and a stable holding current is achieved by adjusting the on / off duty cycle of the second switch by detecting the current in the contactor coil.

9. The contactor control method as described in claim 8, characterized in that, The contactor coil is connected in series with a third switching transistor; The control method further includes turning off the third switch when the contactor should disconnect its contacts.

10. The contactor control method as described in claim 9, characterized in that, The first switch, the second switch, and the third switch each have a first driving circuit, a second driving circuit, and a third driving circuit, respectively. The first drive circuit, the second drive circuit, and / or the third drive circuit are powered by the voltage output from the flyback switching power supply; and The control method further includes: during the pull-in phase, controlling the on / off duty cycle of the second switching transistor based on the voltage feedback of the flyback switching power supply to stabilize the voltage output of the flyback switching power supply.

11. The control method for the contactor according to any one of claims 8 to 10, characterized in that, A filter is provided between the output of the rectifier filter unit and the input of the flyback switching power supply to filter out electromagnetic interference.

12. The control method for the contactor as described in claim 9 or 10, characterized in that, The control method further includes: The system determines whether the contactor should be disconnected based on the output voltage of the rectifier and filter unit. If it determines that the contactor should be disconnected, the system controls the third switch to turn off.

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