Release circuit and control method for contactors

Abstract

The application provides a release circuit and a control method of a contactor. The release circuit of the contactor comprises a first switching device, a protection device, a control circuit and a driving circuit of the first switching device; the first switching device is connected with a coil; the control circuit and the protection device are connected in parallel between a first end of the first switching device and a ground wire; one end of the driving circuit is connected with a second end of the first switching device, and the other end is connected with a third end of the first switching device; the switching state of the first switching device is controlled by the control circuit and the driving circuit; finally, the protection device discharges the energy of the coil based on the breakdown state of the coil when the first switching device is in the off state, so as to control the release time, and greatly reduce the time of delaying the disconnection of the passage caused by the current existing in the coil to attract the armature when the energy is discharged by using the freewheeling diode.

Description

Technical Field

[0001] This invention relates to the field of electrical technology, specifically to a release circuit and control method for a contactor. Background Technology

[0002] Currently, freewheeling diodes are commonly used in coil-related release circuits to release the energy stored in the coil. However, when using freewheeling diodes to release energy, there is still a possibility that current may exist in the coil, which may attract the armature and delay the disconnection of the circuit. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a release circuit and control method for a contactor.

[0004] In a first aspect, in one embodiment, the present invention provides a release circuit for a contactor, the release circuit comprising a first switching device, a protection device, and a control circuit and a drive circuit for the first switching device; wherein the first switching device is connected to a coil in the contactor.

[0005] The control circuit and the protection device are connected in parallel between the first terminal of the first switching device and the ground wire; one end of the drive circuit is connected to the second terminal of the first switching device, and the other end is connected to the third terminal of the first switching device. The control circuit and the drive circuit jointly control the switching state of the first switching device.

[0006] When the first switching device is in the off state, the protection device discharges energy from the coil based on the fact that the coil is in a breakdown state due to the unreleased energy.

[0007] In one embodiment, the release circuit further includes a first diode, which is connected in series with the first switching device and then connected in parallel with the coil; the driving circuit includes a capacitor and a Zener diode connected in parallel, one end of the Zener diode is connected to the second end of the first switching device, and the other end is connected to the third end of the first switching device; the first end of the coil is connected to the busbar.

[0008] In one embodiment, the release circuit further includes a first resistor and a second diode; the first resistor and the second diode are connected in series between the first diode and the third terminal of the first switching device; the control circuit includes a second switching device; the second switching device is connected between the second terminal of the coil and the ground wire;

[0009] The second switching device is turned on under the control of the first control signal, and inputs a high-level signal to the control circuit and the drive circuit so that the current of the bus passes through the coil, the second switching device and the ground wire;

[0010] When the control circuit and the drive circuit input a high-level signal, the second diode is forward-biased, so that the voltage of the bus passes through the first resistor, the second diode, the Zener diode, the first switching device, and the second switching device to the ground wire, and charges the capacitor.

[0011] In one embodiment, the second diode is in a reverse cutoff state when the control circuit inputs a low-level signal and the drive circuit inputs a high-level signal;

[0012] When the control circuit inputs a low-level signal and the drive circuit inputs a high-level signal, the first switching device is in a conducting state based on the voltage across the capacitor, so that the induced electromotive force generated by the coil returns to the bus through the first switching device and the first diode.

[0013] In one embodiment, when the contactor is disconnected, a low-level signal input to the control circuit and a high-level signal input to the drive circuit are maintained for a preset duration. During the preset duration, the first switching device is in a conducting state based on the voltage across the capacitor, so that the induced electromotive force generated by the coil returns to the bus through the first switching device and the first diode.

[0014] In one embodiment, the driving circuit further includes an optocoupler circuit;

[0015] When the control circuit and the drive circuit input a low-level signal, the capacitor releases energy through the optocoupler, thereby controlling the first switching device to be in the off state.

[0016] In one embodiment, when the unreleased energy in the coil is insufficient to break down the protection device, the contactor disconnects, and the remaining energy in the coil is released through leakage current.

[0017] Secondly, in one embodiment, the present invention provides a contactor including the release circuit of the contactor described above;

[0018] When the contactor is in the engaged working state, the coil in the contactor is driven by a pulse width modulation (PWM) signal with a first duty cycle.

[0019] When it is necessary to keep the contactor in the engaged working state, the coil is driven by a PWM signal with a second duty cycle; the first duty cycle and the second duty cycle are determined according to the voltage value of the bus, and the values ​​of the first duty cycle and the second duty cycle are inversely proportional to the voltage value;

[0020] When the contactor is not in the engaged state, the first switching device is turned off after the coil freewheeling is released for a preset time by the drive circuit.

[0021] Thirdly, in one embodiment, the present invention provides a control method for a contactor, applied to the release circuit of the contactor described in any of the above embodiments; the method includes:

[0022] Collect the voltage parameters of the busbar connected to the first end of the coil in the contactor;

[0023] The contactor is controlled to be in a closed state based on the voltage parameters;

[0024] When the contactor is detected to be disconnected, the low-level signal input to the control circuit and the high-level signal input to the drive circuit are maintained for a preset duration.

[0025] When the first switching device is in the off state, the energy of the coil is discharged by the protection device in the breakdown state based on the energy not released by the coil.

[0026] In one embodiment, controlling the contactor to be in a closed state based on the voltage parameter includes:

[0027] A pulse width modulation (PWM) signal with a first duty cycle is determined based on the voltage parameters; the value of the first duty cycle is inversely proportional to the value of the voltage parameters.

[0028] A PWM signal with the first duty cycle is input to the contactor to control the contactor to be in a closed state.

[0029] In one embodiment, prior to detecting that the contactor has disconnected, the method further includes:

[0030] Stop outputting the PWM signal with the first duty cycle to the contactor and turn off the optocoupler circuit in the drive circuit.

[0031] Fourthly, embodiments of the present invention also provide a control device for a contactor, comprising: a memory for storing a computer program; and a processor for executing the computer program to implement the method described in any of the preceding embodiments.

[0032] Fifthly, embodiments of the present invention also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, is used to implement the method described in any of the preceding claims.

[0033] The contactor release circuit and control method provided in this embodiment of the invention include a first switching device, a protection device, and a control circuit and a drive circuit for the first switching device. The first switching device is connected to a coil. The control circuit and the protection device are connected in parallel between the first terminal of the first switching device and the ground wire. One end of the drive circuit is connected to the second terminal of the first switching device, and the other end is connected to the third terminal of the first switching device. The control circuit and the drive circuit jointly control the switching state of the first switching device. Finally, when the first switching device is in the off state, the protection device discharges energy from the coil based on the energy that has not been released and the coil is in a breakdown state. Thus, when the coil is released, the drive circuit controls the first switching device to be in the off state, and the protection device discharges energy from the coil based on the energy that has not been released and the coil is in a breakdown state. This achieves control over the release time and greatly reduces the time when the coil still has current attracting the armature and delaying the opening of the channel when using a freewheeling diode to release energy. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic diagram of the release circuit of a contactor provided in an embodiment of the present invention;

[0036] Figure 2 Another schematic diagram of the release circuit of the contactor provided in an embodiment of the present invention;

[0037] Figure 3 Another schematic diagram of the release circuit of the contactor provided in an embodiment of the present invention;

[0038] Figure 4 Another schematic diagram of the release circuit of the contactor provided in an embodiment of the present invention;

[0039] Figure 5 A schematic diagram of an application scenario of the release circuit of the contactor provided in an embodiment of the present invention;

[0040] Figure 6 A schematic diagram illustrating another application scenario of the contactor release circuit provided in this embodiment of the invention;

[0041] Figure 7 A schematic diagram illustrating another application scenario of the contactor release circuit provided in this embodiment of the invention;

[0042] Figure 8A schematic diagram illustrating another application scenario of the contactor release circuit provided in this embodiment of the invention;

[0043] Figure 9 A flowchart illustrating the control method provided in an embodiment of the present invention;

[0044] Figure 10 This is a schematic diagram illustrating an application scenario of the coil control method provided in an embodiment of the present invention;

[0045] Figure 11 This is a schematic diagram of the control device for the contactor provided in an embodiment of the present invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified. In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use the invention. In the following description, details are set forth for illustrative purposes. It should be understood that those skilled in the art will recognize that the invention can be made without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid unnecessary detail that would obscure the description of the invention. Therefore, the invention is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0049] The terms "first," "second," etc., used in this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or modules is not limited to the listed steps or modules, but may optionally include steps or modules not listed, or may optionally include other steps or modules inherent to these processes, methods, products, or apparatuses.

[0050] In this article, "first terminal," "second terminal," "third terminal," "fourth terminal," etc., are used to describe the ports where a circuit (or a sub-circuit or a circuit branch) connects to other circuits (or sub-circuits or circuit branches), or to describe the ports where electrical signals are received by a circuit (or a sub-circuit or a circuit branch). Different circuits (or sub-circuits or circuit branches) may have ports for external connection. Here, for each circuit (or sub-circuit or circuit branch), the ports used to control whether the circuit (or sub-circuit or circuit branch) operates are named using terms such as "control terminal," and other included ports are distinguished by the naming convention of first terminal, second terminal, etc. In the following descriptions, when referring to the first, second, or third terminal of a circuit (or sub-circuit or circuit branch), the above description can be used as a reference, and further elaboration will not be repeated.

[0051] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0052] In one embodiment, the present invention provides a release circuit for a contactor, such as... Figure 1 As shown, Figure 1 This is a schematic diagram of a contactor release circuit provided in an embodiment of the present invention; the release circuit includes a first switching device Q1, a protection device D3, and a control circuit and a drive circuit for the first switching device Q1; wherein, the first switching device Q1 is connected to the coil.

[0053] It should be noted that the first switching device Q1 can be any switching device, and there is no limitation here. As an example, the first switching device Q1 can be an insulated gate field-effect MOSFET.

[0054] The protection device D3 can be any protection device, and there is no limitation here. As an example, the protection device D3 can be a transient voltage suppressor diode (TVS).

[0055] The protection device D3 is used to protect the first switching device Q1 from overvoltage breakdown. As an example, a TVS diode is used to protect a MOSFET from overvoltage breakdown.

[0056] Both the control circuit and the drive circuit can include input terminals. For example, the input terminal of the control circuit can be denoted as Ctrl; the input terminal of the drive circuit can be denoted as EN_CTRL.

[0057] The control circuit and the protection device D3 are connected in parallel between the first terminal 1 of the first switching device Q1 and the ground line DGND; one end of the drive circuit is connected to the second terminal 2 of the first switching device Q1, and the other end is connected to the third terminal 3 of the first switching device Q1. The control circuit and the drive circuit jointly control the switching state of the first switching device Q1.

[0058] As an example, the first switching device Q1 is a MOSFET; the first terminal of the MOSFET is the drain; the second terminal of the MOSFET is the source; and the third terminal of the MOSFET is the gate.

[0059] The switching states of the first switching device Q1 include an on state and an off state.

[0060] When the first switching device Q1 is in the off state, the protection device D3 discharges energy from the coil based on the fact that the coil is in a breakdown state due to the unreleased energy.

[0061] The energy release of the coil based on the fact that the coil is in a breakdown state can be understood as the energy in the coil not being fully released, generating an induced electromotive force to break down the protection device D3 to quickly release the energy.

[0062] exist Figure 1 The device also includes the contactor J1, with its first terminal 1 connected to the second terminal of the coil, and its second terminal 2 connected to the first terminal of the coil. The first terminal 1 of the protection device D3 is connected to the first terminal 1 of the first switching device Q1, and its second terminal 2 is connected to the ground wire DGND.

[0063] In one embodiment, such as Figure 2 As shown, Figure 2This is another schematic diagram of the release circuit of the contactor provided in an embodiment of the present invention; the release circuit further includes a first diode D2, which is connected in series with the first switching device Q1 and then connected in parallel with the coil; the driving circuit includes a capacitor C1 and a Zener diode ZD1 connected in parallel, one end of the Zener diode ZD1 is connected to the second terminal 2 of the first switching device Q1, and the other end is connected to the third terminal 3 of the first switching device Q1; the first end of the coil is connected to the bus V_B.

[0064] It should be noted that the first diode D2 can be understood as a freewheeling diode. The first switching device Q1 is used to drive whether the freewheeling diode is enabled. As an example, the first switching device Q1 is a MOSFET, which is used to drive whether the freewheeling diode is enabled.

[0065] exist Figure 2 In this circuit, one end of the first diode D2 is connected to the second end 22 of the first switching device Q1, and the other end of the first diode D2 is connected to the first end of the coil. The first end of the coil is connected to the bus V_B.

[0066] In one embodiment, such as Figure 3 As shown, Figure 3 This is another schematic diagram of the release circuit of the contactor provided in an embodiment of the present invention; the release circuit further includes a first resistor R1 and a second diode D1; the first resistor R1 and the second diode D1 are connected in series between the first diode D2 and the third terminal 3 of the first switching device Q1; the control circuit includes a second switching device Q2 and a second resistor R4; the second switching device Q2 and the second resistor R4 are connected in series between the second terminal of the coil and the ground wire DGND;

[0067] The capacitor C1 can be understood as a bootstrap capacitor C1, which can be charged or discharged.

[0068] The second switching device Q2 can be any switching device, and there is no limitation here. As an example, the second switching device Q2 can be an insulated gate field-effect MOSFET. The first terminal of the MOSFET is the drain, the second terminal is the source, and the third terminal is the gate.

[0069] The first switching device Q1 can be a MOS transistor; the first terminal of the MOS transistor is the drain, the second terminal is the source, and the third terminal is the gate.

[0070] The second switching device Q2 is turned on under the control of the first control signal, and inputs a high-level signal to the control circuit and the drive circuit so that the current of the bus V_B passes through the coil, the second switching device Q2, the second resistor R4 to the ground wire. The first control signal is used to control the contactor of the coil to close.

[0071] It should be noted that the first control signal can be a PWM signal, used to control the contactor closure of the coil. The high-level signal can be understood as representing logic "1" in digital circuits, a voltage state opposite to low level (logic "0"). Its specific voltage range varies depending on the circuit standard. The high-level input signal to the control circuit and the drive circuit can be understood as both Ctrl and EN / CTRL inputting high-level signals.

[0072] The current in the busbar V_B can be a high-voltage current; the current in the busbar V_B passing through the coil, the second switching device Q2, and the second resistor R4 to the ground wire can be understood as a high-voltage current passing through the coil, Q2, and R4 to GND.

[0073] When the control circuit and the drive circuit receive a high-level input signal, the second diode D1 is forward-biased, allowing the voltage of the bus V_B to pass through the first resistor R1, the second diode D1, the Zener diode ZD1, the first switching device Q1, and the second switching device Q2 to the ground line DGND, thus charging the capacitor C1. As the capacitor C1 is charged, the voltage across it gradually increases.

[0074] The voltage of the bus V_B can be a high-voltage signal. The voltage of the bus V_B flows through the first resistor R1, the second diode D1, the Zener diode ZD1, the first switching device Q1, and the second switching device Q2 to the ground wire DGND. The high-voltage signal of the bus V_B can flow through R1, D1, ZD1, Q1, and Q2 to GND.

[0075] Specifically, when both Ctrl and EN_CTRL are high, Q2 is turned on, and high-voltage current flows through the coil, Q2, and R4 to GND; at this time, the high-voltage signal flows through R1, D1, ZD1, Q1, and Q2 to GND, and the voltage across the bootstrap capacitor C1 gradually increases.

[0076] As an example, the voltage of the bus V_B may include a minimum bus voltage and a maximum bus voltage; the minimum bus voltage may be denoted as V_B. min The maximum bus voltage is denoted as V_B. max; The on-time of driving Q2 can be denoted as T_on; the duty cycle of the PWM signal can be denoted as D; the maximum freewheeling time can be denoted as T_hold; the turn-on voltage of Q1 can be denoted as VGS; the maximum operating current of the Zener diode can be denoted as IZD_max; the minimum operating current of the Zener diode can be denoted as IZD_min; the operating voltage of the Zener diode can be denoted as VZD; the maximum withstand voltage of Q1 and Q2 can be denoted as VDS, the maximum clamp voltage can be denoted as VS_max, and the minimum clamp voltage can be denoted as VTVS_min; the resistance value selection of the current-limiting resistor R1 can satisfy (V_B_min-VZD) / IZD_max<R1<(V_B_max-VZD) / IZD_min; the package of the current-limiting resistor R1 can be selected based on (V_B_max-VZD)^2 / R1*D, a suitable package is selected according to the calculated power, and the withstand voltage of the resistor needs to be considered; the turn-on voltage selection of Q1 can satisfy VZD>VGS, that is, the voltage of the Zener diode > the turn-on voltage of Q1; the requirement for the capacitor C1 can satisfy VGS<V_B_min(1-e^(T_on / RC)), after Q2 is turned on, the charging voltage of the capacitor C1 is greater than the turn-on voltage of Q1; during fast turn-off, the time during which the terminal voltage of C1 is greater than VGS is longer than T_hold, at this time, the capacitor current is discharged through the Zener diode, the current of the Zener diode varies with the operating voltage and cannot be estimated, actual testing is required, and empirically, the capacitance value of C1 can be selected as 0.1uf. The selection of TVS can satisfy VTVS_min>V_B_max, VS_max<VDS.

[0077] In Figure 3 , one end of the second diode D1 is connected to the third terminal 3 of the first switching device Q1, and the other end of the second diode D1 is connected to one end of the first resistor R1; the other end of the first resistor R1 is connected to the first end of the coil. The second terminal 2 of the second switching device Q2 is connected to Ctrl, the first terminal 1 of the second switching device Q2 is connected to the second end of the coil, the second terminal 2 of the second switching device Q2 is connected to one end of the second resistor R4, and the other end of the second resistor R4 is connected to the ground line DGND.

[0078] In one embodiment, the second diode D1 is in a reverse cutoff state when the control circuit inputs a low-level signal and the drive circuit inputs a high-level signal;

[0079] That the second diode D1 is in a reverse cutoff state when the control circuit inputs a low-level signal and the drive circuit inputs a high-level signal can be understood as: when Ctrl is at a low level and EN_CTRL is at a high level, the voltage across the capacitor C1 cannot change abruptly, and the second diode D1 is in a reverse cutoff state.

[0080] When the control circuit inputs a low-level signal and the drive circuit inputs a high-level signal, the first switching device Q1 is in a conducting state based on the voltage across the capacitor C1, so that the induced electromotive force generated by the coil returns to the bus V_B through the first switching device Q1 and the first diode D2.

[0081] When the control circuit inputs a low-level signal and the drive circuit inputs a high-level signal, the first switching device Q1 is in a conducting state based on the voltage across capacitor C1. This can be understood as Ctrl being low and EN_CTRL being high. The voltage across the capacitor cannot change abruptly, and the voltage stored in C1 at this time turns on Q1.

[0082] The induced electromotive force generated by the coil returns to the bus V_B through the first switching device Q1 and the first diode D2. This can be understood as the induced electromotive force generated by the coil returning to V_B through Q1 and D2.

[0083] Specifically, when Ctrl is low and EN_CTRL is high, the voltage across the capacitor cannot change abruptly. At this time, the voltage stored in C1 turns on Q1, causing the induced electromotive force generated by the coil to return to V_B through Q1 and D2. Diode D1 is reverse-biased and cut off to prevent the energy of capacitor C1 from being released through R1, thereby keeping Q1 continuously on.

[0084] In one embodiment, when the contactor is disconnected, a low-level signal input to the control circuit and a high-level signal input to the drive circuit are maintained for a preset duration. During the preset duration, the first switching device Q1 is in a conducting state based on the voltage across the capacitor C1, so that the induced electromotive force generated by the coil returns to the bus V_B through the first switching device Q1 and the first diode D2.

[0085] It should be noted that the preset duration can be determined according to the actual situation and is not limited here. As an example, the preset duration can be 10ms. The preset duration for the low-level signal input to the control circuit and the high-level signal input to the drive circuit can be 10ms for Ctrl to be low and EN_CTRL to be high.

[0086] Specifically, when the contactor needs to be disconnected, Ctrl is low and EN_CTRL is high for 10ms, returning most of the energy in the coil to V_B through Q1 and D2.

[0087] In one embodiment, such as Figure 4 As shown, Figure 4This is another schematic diagram of the release circuit of the contactor provided in an embodiment of the present invention; the driving circuit further includes an optocoupler circuit, one end of which is connected to the second end of the first switching device, and the other end of which is connected to the third end of the first switching device;

[0088] When the control circuit inputs a low-level signal and the drive circuit inputs a low-level signal, the capacitor C1 releases energy through the optocoupler, thereby controlling the first switching device 101 to be in the off state.

[0089] The optocoupler, also known as an optocoupler circuit or photocoupler, transmits signals through an "electrical-optical-electrical" conversion. The optocoupler circuit includes an optocoupler U1, a device that transmits electrical signals using light as a medium. It typically consists of a light emitter and a light receiver. The light emitter is usually an infrared light-emitting diode (LED), while the light receiver is a photosensitive semiconductor tube. When the light emitter receives an electrical signal, it emits light; the light receiver receives the light and generates a photocurrent, thus achieving the "electrical-optical-electrical" conversion. By controlling the on / off state of the optocoupler circuit, the release time of the release circuit can be controlled. That is, this invention uses a new release circuit; when the coil releases, the on / off state of the freewheeling circuit is controlled by the on / off state of the optocoupler circuit, thereby controlling the release time.

[0090] The capacitor C1 releases energy through the optocoupler circuit, thereby controlling the first switching device 101 to be in the off state. Alternatively, the voltage across the capacitor C1 can be pulled low through the optocoupler circuit, thereby controlling the first switching device 101 to be in the off state.

[0091] The low-level input signal for the control circuit and the low-level input signal for the drive circuit can both be Ctrl and EN_CTRL, both at a low level.

[0092] The voltage across capacitor C1 being pulled down by the optocoupler circuit can be understood as a rapid drop in the voltage of capacitor C1.

[0093] Specifically, when both Ctrl and EN_CTRL are low, the energy of the bootstrap capacitor returns through the output of the optocoupler, causing the voltage of the bootstrap capacitor C1 to drop rapidly, thereby turning off Q1.

[0094] exist Figure 4 In the above, the first terminal 1 of the optical coupler U1 is connected to EN_CTRL, the second terminal 2 of the optical coupler U1 is connected to one end of the capacitor C1, and the third terminal 3 of the optical coupler U1 is connected to the other end of the capacitor C1.

[0095] In one embodiment, when the unreleased energy in the coil is insufficient to break down the protection device D3, the contactor disconnects, and the remaining energy in the coil is released through leakage current.

[0096] The fact that the energy not released by the coil cannot break down the protective device D3 can be understood as the induced electromotive force generated in the coil being insufficient to break down D3.

[0097] The release of residual energy in the coil through leakage current can be understood as the free release of residual energy in the coil.

[0098] Specifically, after the induced electromotive force generated in the coil is insufficient to break down D3, the magnetism weakens due to the lack of current change, the contactor disconnects, and the remaining energy in the coil is slowly released through leakage current.

[0099] In practical applications, the release circuit of a contactor can be understood as a controllable and fast-release circuit for a contactor, such as... Figure 5 As shown, Figure 5 This is a schematic diagram of an application scenario of the contactor release circuit provided in an embodiment of the present invention. The optocoupler circuit further includes a third resistor R2 and a second capacitor C2. The optocoupler U1 also includes a fourth terminal 1, which is connected to one end of the third resistor R2. The other end of the third resistor R2 is connected to a +3.3V voltage, and the other end of the third resistor R2 is also connected to one end of the second capacitor C2. The other end of the second capacitor C2 is connected to ground DGND. The control circuit further includes a fourth resistor R3 and a fifth resistor R4. One end of the fourth resistor R3 is connected to Ctrl, and the other end is connected to the second terminal 2 of the second switching device Q2. One end of the fifth resistor R5 is connected to the second terminal 2 of the second switching device Q2, and the other end is connected to ground DGND.

[0100] The first switching device Q1 is a MOSFET; the protection device D3 is a TVS diode. A MOSFET Q1 (used to control whether the freewheeling diode is enabled) and a TVS diode D3 (used to protect the MOSFET from overvoltage breakdown) and a drive circuit for Q1 are added to the normal drive circuit. A PWM signal is provided to Q2 when the contactor needs to close. The circuit operation details are as follows:

[0101] like Figure 6 As shown, Figure 6 This is a schematic diagram of another application scenario of the release circuit of the contactor provided in the embodiment of the present invention; when Ctrl and EN_CTRL are both high level, Q2 is turned on, and the high voltage current flows through the coil, Q2, R4 to GND; at this time, the high voltage signal flows to GND through R1, D1, ZD1, Q1, Q2, and the voltage across the bootstrap capacitor C1 gradually increases.

[0102] like Figure 7 As shown, Figure 7 This is a schematic diagram of another application scenario of the release circuit of the contactor provided in the embodiment of the present invention; subsequently, when Ctrl is low and EN_CTRL is high, the voltage across the capacitor cannot change abruptly. At this time, the voltage stored in C1 turns on Q1, so that the induced electromotive force generated by the coil returns to V_B through Q1 and D2. Diode D1 is reverse cut off to prevent the energy of capacitor C1 from being released through R1, thereby keeping Q1 continuously turned on.

[0103] like Figure 8 As shown, Figure 8 This is a schematic diagram of another application scenario of the contactor release circuit provided in this embodiment of the invention. When the contactor needs to be disconnected, Ctrl is low and EN_CTRL is high for 10ms, returning most of the energy in the coil to V_B through Q1 and D2. Subsequently, both Ctrl and EN_CTRL are low, and the energy of the bootstrap capacitor returns through the output of the optocoupler, causing the voltage of the bootstrap capacitor C1 to drop rapidly, thereby causing Q1 to turn off. Since the energy in the coil is not completely released, an induced electromotive force is generated to break down the TVS diode D3 and quickly discharge the energy. After the induced electromotive force in the coil is insufficient to break down D3, the magnetism weakens due to the lack of current change, and the contactor disconnects. The remaining energy in the coil is slowly released through leakage current.

[0104] This invention uses a new release circuit to control the on / off state of the freewheeling circuit when the coil is released, thereby controlling the release time.

[0105] In a second aspect, the present invention provides a contactor including the release circuit of the contactor described above;

[0106] When the contactor is in the engaged working state, the coil in the contactor is driven by a pulse width modulation (PWM) signal with a first duty cycle.

[0107] When it is necessary to keep the contactor in the engaged working state, the coil is driven by a PWM signal with a second duty cycle; the first duty cycle and the second duty cycle are determined according to the voltage value of the bus, and the values ​​of the first duty cycle and the second duty cycle are inversely proportional to the voltage value;

[0108] When the contactor is not in the engaged state, the first switching device is turned off after the coil freewheeling is released for a preset time by the drive circuit.

[0109] The preset time can be determined according to the actual situation and is not limited here. As an example, the preset time can be 10 seconds.

[0110] It should be noted that both the first duty cycle and the second duty cycle can be determined according to the actual situation, and are not limited here. As an example, the second duty cycle is smaller than the first duty cycle. For example, during the pull-in phase, the coil is driven by a PWM signal with the first duty cycle; during the hold phase, the coil is driven by a PWM signal with a smaller second duty cycle; and during the release phase, the coil freewheeling current is released by the drive circuit and Q1 is turned off after a preset time.

[0111] The fact that the values ​​of the first duty cycle and the second duty cycle are inversely proportional to the voltage value can be understood as the values ​​of the first duty cycle and the second duty cycle being determined based on the magnitude of the bus voltage, and the magnitude of the duty cycle being inversely proportional to the magnitude of the voltage.

[0112] The driving circuit may include an optocoupler circuit, and the freewheeling time can be controlled by controlling the on / off state of the optocoupler circuit.

[0113] Thirdly, such as Figure 9 As shown, Figure 9 This is a flowchart illustrating a control method provided in an embodiment of the present invention, applied to the release circuit of a contactor in any of the above embodiments. It includes the following steps:

[0114] S1, collect the voltage parameters of the busbar connected to the first end of the coil in the contactor.

[0115] Here, the contactor is externally powered on, and the voltage parameters of the bus connected to the first end of the coil in the contactor are collected. The voltage parameters include the voltage value.

[0116] S2, based on the voltage parameters, control the contactor to be in a closed state.

[0117] The control method can be determined according to the actual situation and is not limited here. As an example, controlling the contactor to be in a closed state based on the voltage parameters may include determining a pulse width modulation (PWM) signal with a first duty cycle based on the voltage parameters; the value of the first duty cycle is inversely proportional to the value of the voltage parameters; and inputting the PWM signal with the first duty cycle to the contactor to control the contactor to be in a closed state.

[0118] It should be noted that the value of the first duty cycle is inversely proportional to the value of the voltage parameter, which can be understood as the larger the value of the voltage parameter, the smaller the value of the first duty cycle; the smaller the value of the voltage parameter, the larger the value of the first duty cycle.

[0119] As an example, a pulse width modulation (PWM) signal with a duty cycle of 30-50% is determined based on the voltage parameters; the PWM signal with a duty cycle of 30-50% is input to the contactor to control the contactor to be in a closed state.

[0120] S3, when the contactor is detected to be disconnected, the low-level signal input to the control circuit and the high-level signal input to the drive circuit are maintained for a preset duration.

[0121] The preset duration can be determined according to actual conditions and is not limited here. As an example, the preset duration can be 10ms. The preset duration for the low-level signal input to the control circuit and the high-level signal input to the drive circuit can be 10ms.

[0122] In one embodiment, prior to detecting that the contactor has disconnected, the method further includes:

[0123] Stop outputting the PWM signal with the first duty cycle to the contactor and turn off the optocoupler circuit in the drive circuit.

[0124] In this embodiment, stopping the output of the first duty cycle PWM signal to the contactor can be understood as stopping the PWM output and no longer driving the contactor coil.

[0125] S4, when the first switching device is in the off state, the energy of the coil is discharged by the protection device in the breakdown state based on the energy not released by the coil.

[0126] The energy release from the coil, which is based on the energy not released by the coil causing the protection device to be in a breakdown state, can be understood as the energy in the coil not being fully released, generating an induced electromotive force to break down the protection device and rapidly release energy.

[0127] In practical applications, the control method can be understood as the control method of the contactor's release circuit, such as... Figure 10 As shown, Figure 10This is a schematic diagram illustrating an application scenario of the coil control method provided in this embodiment of the invention. To reduce power consumption, the V_B voltage can be acquired. When the V_B voltage is low, the PWM duty cycle for initiating contactor engagement is large; when the V_B voltage is high, the PWM duty cycle for initiating contactor engagement is small. After the contactor is stably engaged, the PWM duty cycle can be reduced to maintain contactor engagement. The specific duty cycle needs to be tested based on the actual coil. One example of the contactor control logic is that an external power supply powers the contactor, and the contactor acquires the bus voltage. The acquired bus voltage is sent to the MCU; the MCU sends a PWM with a duty cycle of 30-50% to drive the contactor to engage based on the acquired bus voltage. The higher the bus voltage, the smaller the duty cycle; the lower the bus voltage, the larger the duty cycle. After the contactor engages, the PWM duty cycle is reduced to maintain contactor engagement; at this time, the duty cycle is less than 10%. When it is detected that the contactor needs to be turned off, the PWM output is stopped, and the contactor coil is no longer driven. The optocoupler remains off, allowing coil energy to be released through Q1 and the freewheeling diode. The timer determines whether the contactor release time has been reached. When the release time is reached, the optocoupler is activated, releasing the energy from the bootstrap capacitor and turning off Q1. Remaining energy is discharged through the TVS, causing the contactor to disconnect, thus completing the contactor control and ending the contactor control process.

[0128] To implement the method of the embodiments of the present invention, such as Figure 11 As shown, Figure 11 This is a schematic diagram of the structure of a contactor control device provided in an embodiment of the present invention. The control device 110 of the contactor may include: a memory 1101 for storing a computer program; and a processor 1102 for executing the computer program to implement the method described in any of the above-described methods. For example, the processor 1102 may be used to: acquire the voltage parameters of the bus V_B connected to the first end of the coil; control the contactor to be in a closed state based on the voltage parameters; when the contactor is detected to be open, continuously send a low-level signal to the control circuit and a high-level signal to the drive circuit for a preset duration; and when the first switching device is in a closed state, discharge energy from the coil by causing the protection device to be in a breakdown state based on the energy not released by the coil. The processor 1102 may also implement any of the steps in the methods described above, which will not be repeated here.

[0129] It should be noted that the control device and control method embodiments of the contactor provided in the above embodiments belong to the same concept, and the specific implementation process can be found in the method embodiments, which will not be repeated here.

[0130] Of course, in practical applications, such as Figure 11As shown, the control device 110 of the contactor may further include at least one network interface 1103. The various components in the control device of the contactor are coupled together via a bus system 1104. It is understood that the bus system 1104 is used to realize communication between these components. In addition to a data bus, the bus system 1104 also includes a power bus, a control bus, and a status signal bus. However, for clarity, in... Figure 11 Various buses are labeled as bus system 1104. The number of processors 1102 can be at least one. Network interface 1103 is used for wired or wireless communication between the contactor's control device and other devices. Memory 1101 in this embodiment is used to store various types of data to support the operation of the contactor's control device. The methods disclosed in the above embodiments of the present invention can be applied to processor 1102, or implemented by processor 1102. Processor 1102 may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method can be completed by integrated logic circuits in the hardware of processor 1102 or by instructions in software form. Processor 1102 can be a general-purpose processor, a digital signal processor (DSP), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Processor 1102 can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. A general-purpose processor can be a microprocessor or any conventional processor, etc. The steps of the method disclosed in the embodiments of the present invention can be directly manifested as the combined execution of hardware and software modules in a microcontroller. The software modules can reside in a storage medium, specifically memory 1101. The processor 1102 reads information from memory 1101 and, in conjunction with its hardware, completes the steps of the aforementioned method. In an exemplary embodiment, the control device 110 of the contactor can be implemented by one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers (MCUs), microprocessors, or other electronic components to execute the aforementioned method.

[0131] Specifically, embodiments of the present invention provide a computer-readable storage medium storing a computer program thereon, such as a memory 1101 storing the computer program, which can be executed by a processor 1102 to complete the steps described in the aforementioned method. The computer-readable storage medium may be a memory such as FRAM, ROM, PROM, EPROM, EEPROM, Flash Memory, magnetic surface memory, optical disc, or CD-ROM.

[0132] In addition, in the various embodiments of the present invention, each functional unit can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be implemented in hardware or in the form of hardware plus software functional units.

[0133] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0134] Alternatively, if the integrated units of this invention are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROM, RAM, magnetic disks, or optical disks.

[0135] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the detailed descriptions of other embodiments above, which will not be repeated here.

[0136] The release circuit and control method of a contactor provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

[0137] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A release circuit for a contactor, characterized in that, The release circuit includes a first switching device, a protection device, and a control circuit and a drive circuit for the first switching device; wherein the first switching device is connected to the coil in the contactor; The control circuit and the protection device are connected in parallel between the first terminal of the first switching device and the ground wire; one end of the drive circuit is connected to the second terminal of the first switching device, and the other end is connected to the third terminal of the first switching device. The control circuit and the drive circuit jointly control the switching state of the first switching device. When the first switching device is in the off state, the protection device discharges energy from the coil based on the fact that the coil is in a breakdown state due to the unreleased energy. The release circuit further includes a first diode, which is connected in series with the first switching device and then connected in parallel with the coil; the driving circuit includes a capacitor and a Zener diode connected in parallel, one end of the Zener diode is connected to the second end of the first switching device, and the other end is connected to the third end of the first switching device; the first end of the coil is connected to the busbar; The release circuit further includes a first resistor and a second diode; the first resistor and the second diode are connected in series between the first diode and the third terminal of the first switching device; the control circuit includes a second switching device; the second switching device is connected between the second terminal of the coil and the ground wire.

2. The release circuit of the contactor according to claim 1, characterized in that, The second switching device is turned on under the control of the first control signal, and inputs a high-level signal to the control circuit and the drive circuit so that the current of the bus passes through the coil, the second switching device and the ground wire; When the control circuit and the drive circuit input a high-level signal, the second diode is forward-biased, so that the voltage of the bus passes through the first resistor, the second diode, the Zener diode, the first switching device, and the second switching device to the ground wire, and charges the capacitor.

3. The release circuit of the contactor according to claim 2, characterized in that, The second diode is in a reverse cutoff state when the control circuit inputs a low-level signal and the drive circuit inputs a high-level signal; When the control circuit inputs a low-level signal and the drive circuit inputs a high-level signal, the first switching device is in a conducting state based on the voltage across the capacitor, so that the induced electromotive force generated by the coil returns to the bus through the first switching device and the first diode.

4. The release circuit of the contactor according to claim 3, characterized in that, When the contactor is disconnected, the low-level signal input to the control circuit and the high-level signal input to the drive circuit are maintained for a preset duration. During the preset duration, the first switching device is in a conducting state based on the voltage across the capacitor, so that the induced electromotive force generated by the coil returns to the bus through the first switching device and the first diode.

5. The release circuit of the contactor according to claim 4, characterized in that, The driving circuit also includes an optocoupler circuit, one end of which is connected to the second end of the first switching device, and the other end of which is connected to the third end of the first switching device. When the control circuit and the drive circuit input a low-level signal, the capacitor releases energy through the optocoupler, thereby controlling the first switching device to be in the off state.

6. The release circuit of the contactor according to any one of claims 1-5, characterized in that, When the energy not released by the coil is insufficient to break down the protection device, the contactor disconnects, and the remaining energy in the coil is released through leakage current.

7. A contactor, characterized in that, Includes the release circuit of the contactor as described in any one of claims 1-6; When the contactor is in the engaged working state, the coil in the contactor is driven by a pulse width modulation (PWM) signal with a first duty cycle. When it is necessary to keep the contactor in the engaged state, the coil is driven by a PWM signal with a second duty cycle; The first duty cycle and the second duty cycle are determined based on the bus voltage value, and the values ​​of the first duty cycle and the second duty cycle are inversely proportional to the voltage value; When the contactor is not in the engaged state, the first switching device is turned off after the coil freewheeling is released for a preset time by the drive circuit.

8. A control method for a contactor, characterized in that, The method, applied to the release circuit of the contactor according to any one of claims 1-6, comprises: Collect the voltage parameters of the busbar connected to the first end of the coil in the contactor; The contactor is controlled to be in a closed state based on the voltage parameters; When the contactor is detected to be disconnected, the low-level signal input to the control circuit and the high-level signal input to the drive circuit are maintained for a preset duration. When the first switching device is in the off state, the energy of the coil is discharged by the protection device in the breakdown state based on the energy not released by the coil.

9. The method according to claim 8, characterized in that, The step of controlling the contactor to be in a closed state based on the voltage parameters includes: A pulse width modulation (PWM) signal with a first duty cycle is determined based on the voltage parameters; the value of the first duty cycle is inversely proportional to the value of the voltage parameters. A PWM signal with the first duty cycle is input to the contactor to control the contactor to be in a closed state.

10. The method according to claim 9, characterized in that, The driving circuit includes an optocoupler circuit, and the method further includes, prior to detecting that the contactor is disconnected: Stop outputting the PWM signal with the first duty cycle to the contactor and turn off the optocoupler circuit in the drive circuit.

Images