Contactor state detection circuit

Abstract

The utility model provides a contactor state detection circuit. The contactor state detection circuit comprises a rectification circuit, a switch tube Q1, a relay K1 and a controller, the input end of the rectification circuit is used for being connected with the output end of a contactor, the output end of the rectification circuit is used for being connected with the control end of the switch tube Q1, and the switch tube Q1 is used for controlling power-on or power-off of a coil of the relay K1. A first end of a normally open contact of the relay K1 is connected with a first power supply, a second end of the normally open contact of the relay K1 is connected to a first signal input end of the controller, and the controller is configured to read a control signal of the contactor, compare the level of the control signal of the contactor with the level of the first signal input end, and output the control signal of the contactor; and determining a state detection result of the contactor based on the comparison result. The fault of the contactor or the relay can be found in time.

Description

Technical Field

[0001] The present disclosure relates to the field of automatic detection technology, and in particular to a contactor state detection circuit. Background Art

[0002] In the field of automatic control, contactors are commonly used to control the power supply of equipment. For example, a charging pile system requires contactors in two parts: an AC contactor (or relay) on the input side, which closes when charging is started to provide power input to the power module; and a DC contactor on the output side, which closes during charging to output energy and charge the electric vehicle. Failures in either the AC or DC contactor can affect the normal operation of the charging pile. Therefore, it is necessary to monitor the operating status of the contactors in real time and accurately transmit this status to the charging pile control unit. Utility Model Content

[0003] The embodiments of the present disclosure provide a contactor status detection circuit to promptly detect contactor or relay failures.

[0004] The embodiment of the present disclosure provides a contactor state detection circuit, including a rectifier circuit, a switch tube Q1, a relay K1 and a controller.

[0005] The input end of the rectifier circuit is used to be connected to the output end of the contactor, and the output end of the rectifier circuit is used to be connected to the control end of the switch tube Q1. The switch tube Q1 is used to control the power on or off of the coil of the relay K1. The first end of the normally open contact of the relay K1 is connected to the first power supply, and the second end of the normally open contact of the relay K1 is connected to the first signal input end of the controller.

[0006] The controller is configured to: read a control signal of the contactor, compare a level of the control signal of the contactor with a level of the first signal input terminal, and determine a state detection result of the contactor based on the comparison result.

[0007] In an exemplary embodiment of the present disclosure, a current limiting filter circuit is provided between the output end of the rectifier circuit and the switch tube Q1. The current limiting filter circuit includes a current limiting resistor branch consisting of a plurality of current limiting resistors connected in series, and a capacitor C1.

[0008] The first end of the current-limiting resistor branch is connected to the output end of the rectifier circuit, the second end of the current-limiting resistor branch is used to be connected to the control end of the switch tube Q1, the first end of the capacitor C1 is connected to the midpoint of the current-limiting resistor branch, and the second end of the capacitor C1 is grounded; the midpoint of the current-limiting resistor branch is the connection point located in the middle of the connection points of multiple current-limiting resistors.

[0009] In an exemplary embodiment of the present disclosure, an isolation optocoupler is provided between the current limiting filter circuit and the switch tube Q1.

[0010] In an exemplary embodiment of the present disclosure, the contactor state detection circuit further includes:

[0011] An XOR gate circuit, wherein the first input end of the XOR gate circuit is connected to the control end of the contactor, the second input end of the XOR gate circuit is connected to the second end of the normally open contact of the relay K1, and the output end of the XOR gate circuit is connected to the first signal input end of the controller.

[0012] In an exemplary embodiment of the present disclosure, the contactor state detection circuit further includes a NOT gate circuit, an AND gate circuit, a resistor R20 and a capacitor C2.

[0013] The control signal of the contactor is connected to the first input terminal of the AND gate circuit, the second terminal of the normally open contact of the relay K1 is connected to the second input terminal of the AND gate circuit through the NOT gate, the output terminal of the AND gate circuit is connected to the first terminal of the capacitor C2 through the resistor R20, and the second terminal of the capacitor C2 is grounded.

[0014] The controller is configured to read the terminal voltage of the capacitor C2 and determine the action time of the contactor based on the terminal voltage of the capacitor C2.

[0015] In an exemplary embodiment of the present disclosure, the contactor state detection circuit further includes an operational amplifier U4, the non-inverting input terminal of the operational amplifier U4 is connected to the first end of the capacitor C2, the output terminal of the operational amplifier U4 is feedback-connected to the inverting input terminal of the operational amplifier U4, and the output terminal of the operational amplifier U4 is connected to the AD channel of the controller.

[0016] In an exemplary embodiment of the present disclosure, the contactor state detection circuit further includes:

[0017] The temperature detection module is used to detect the contact temperature of the contactor, and the output end of the temperature detection module is connected to the second signal input end of the controller.

[0018] The contactor state detection circuit provided by the embodiment of the present disclosure has the following working principles and beneficial effects:

[0019] In the embodiment of the present disclosure, the input end of the contactor is connected to the power supply, and the output end is connected to the input end of the rectifier circuit. When a control signal is sent to the contactor to control the contactor to close, if the contactor is closed normally, its output end is connected to the power supply, and a voltage signal is output at the output end of the rectifier circuit. The switch tube Q1 is turned on, the relay K1 coil is energized, the first end and the second end of the normally open contact of the relay K1 are turned on, and the first signal input end of the controller receives a high-level signal. Based on this, it can be judged that the contactor has been closed normally. Conversely, if the first signal input end of the controller receives a low-level signal, it is judged that the contactor has not been closed normally.

[0020] When a control signal is sent to the contactor to control the contactor to disconnect, if the contactor disconnects normally, its output end is disconnected from the power supply, no voltage signal is output from the output end of the rectifier circuit, the switch tube Q1 is cut off, the relay K1 coil is de-energized, the first end and the second end of the normally open contact of the relay K1 are disconnected, and the first signal input end of the controller receives a low-level signal, based on which it can be judged that the contactor has been disconnected normally. Conversely, if the first signal input end of the controller receives a high-level signal, it is judged that the contactor has not been disconnected normally.

[0021] The embodiment of the present disclosure detects the contactor's energized state in real time through the rectifier circuit, switch tube Q1, and relay K1, and compares it with the contactor's control signal. If the two are consistent, it indicates that the contactor is working normally; otherwise, it is judged that the contactor is faulty, thereby achieving timely detection of contactor faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0023] Figure 1 is a circuit schematic diagram of a contactor state detection circuit provided in one embodiment of the present disclosure;

[0024] Figure 2 is a circuit schematic diagram of a contactor state detection circuit provided by another embodiment of the present disclosure;

[0025] Figure 3 Schematic diagram of the connection relationship between the NOT gate circuit and the AND gate circuit provided by the embodiment of the present disclosure;

[0026] Figure 4 Schematic diagram of the contactor action time detection principle provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] To help those skilled in the art better understand this solution, the following will clearly describe the technical solutions in the embodiments of this solution in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of this solution, not all of it. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of this solution.

[0028] Throughout the specification, claims, and accompanying figures of this solution, the term "including" and any variations thereof mean "including, but not limited to," and are intended to cover non-exclusive inclusions and are not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish between different objects, not to describe a specific order.

[0029] The following describes the implementation of the present disclosure in detail with reference to the accompanying drawings:

[0030] Figure 1 This is a principle block diagram of a contactor state detection circuit provided by an embodiment of the present disclosure. Figure 1 The contactor state detection circuit includes a rectifier circuit, a switch tube Q1, a relay K1 and a controller.

[0031] The input end of the rectifier circuit is used to connect to the output end of the contactor, and the output end of the rectifier circuit is used to connect to the control end of the switch tube Q1. The switch tube Q1 is used to control the power on or off of the relay K1 coil. The first end of the normally open contact of the relay K1 is connected to the first power supply, and the second end of the normally open contact of the relay K1 is connected to the first signal input end of the controller.

[0032] The controller is configured to: read a control signal of the contactor, compare a level of the control signal of the contactor with a level of the first signal input terminal, and determine a state detection result of the contactor based on the comparison result.

[0033] In this embodiment, the input end of the contactor is connected to the power supply, and the output end is connected to the input end of the rectifier circuit. The controller communicates with the control unit of the contactor and reads the control signal of the contactor. When the control unit of the contactor sends a control signal to the contactor and controls the contactor to close, if the contactor is closed normally, its output end is connected to the power supply, and a voltage signal is output at the output end of the rectifier circuit. The switch tube Q1 is turned on, the coil of the relay K1 is energized, the first end DO1 and the second end DO2 of the normally open contact of the relay K1 are turned on, and the first signal input end of the controller receives a high-level signal. Based on this, it can be judged that the contactor has been closed normally. Conversely, if the first signal input end of the controller receives a low-level signal, it is judged that the contactor is not closed normally.

[0034] When the control unit of the contactor sends a control signal to the contactor to control the contactor to disconnect, if the contactor is disconnected normally, its output end is disconnected from the power supply, there is no voltage signal output at the output end of the rectifier circuit, the switch tube Q1 is cut off, the relay K1 coil is de-energized, the first end DO1 and the second end DO2 of the normally open contact of the relay K1 are disconnected, and the first signal input end of the controller receives a low-level signal, based on which it can be judged that the contactor has been disconnected normally. Conversely, if the first signal input end of the controller receives a high-level signal, it is judged that the contactor has not been disconnected normally.

[0035] Since the rectifier circuit can convert an AC voltage signal into a DC voltage signal, this embodiment can be used to detect the working state of both AC contactors and DC contactors. Similarly, this embodiment is also applicable to detecting the working state of relays.

[0036] From the above, it can be concluded that this embodiment detects the contactor's pull-in state in real time through the rectifier circuit, the switch tube Q1, and the relay K1, and compares it with the control signal of the contactor. If the two are consistent, it indicates that the contactor is working normally. Otherwise, it is judged that the contactor is faulty, thereby achieving timely detection of contactor faults.

[0037] Reference Figure 1 In an exemplary embodiment of the present disclosure, a current limiting filter circuit is provided between the output end of the rectifier circuit and the switch tube Q1. The current limiting filter circuit includes a current limiting resistor branch consisting of a plurality of current limiting resistors connected in series, and a capacitor C1.

[0038] The first end of the current-limiting resistor branch is connected to the output end of the rectifier circuit, the second end of the current-limiting resistor branch is used to connect to the control end of the switch tube Q1, the first end of the capacitor C1 is connected to the midpoint of the current-limiting resistor branch, and the second end of the capacitor C1 is grounded; the midpoint of the current-limiting resistor branch is the connection point located in the middle of the connection points of the multiple current-limiting resistors.

[0039] In this embodiment, a plurality of current-limiting resistors R2 to R11 connected in series are used to limit the output current of the rectifier bridge, and the capacitor C1 can play a filtering role so that the control end of the switch tube Q1 obtains a stable level signal.

[0040] Furthermore, after a large number of experimental studies, the inventors found that if the filter capacitor C1 is connected to the output end of the rectifier circuit, it is necessary to select a capacitor with a rated voltage greater than the output voltage of the rectifier circuit, and the required capacitor rated voltage is higher. If the filter capacitor C1 is connected to the end of the current limiting resistor (that is, the end close to the resistor R11), although a capacitor with a lower rated voltage can be selected, the voltage near the zero point of the pulsating DC voltage output by the rectifier circuit will be too small and the switch tube Q1 will not be able to turn on. Therefore, the filter capacitor C1 is connected to the middle position of the current limiting resistor branch, and a capacitor with a lower rated voltage can be selected, and a smooth DC voltage with an amplitude of half the peak voltage of the filter output can be obtained to ensure that the switch tube Q1 is reliably turned on.

[0041] It can be concluded from the above that the configuration of the current limiting filter circuit in this embodiment can ensure that the control end of the switch tube Q1 obtains a safe and stable voltage signal, thereby facilitating reliable conduction of the switch tube Q1.

[0042] Reference Figure 1 In an exemplary embodiment of the present disclosure, an isolation optocoupler is provided between the current limiting filter circuit and the switch tube Q1.

[0043] In this embodiment, the isolating optocoupler plays a role of electrical isolation, preventing interference signals on one side of the contactor from entering the circuit where the relay K1 is located, thereby preventing the relay K1 from being mis-conducted.

[0044] Furthermore, after a large number of experimental studies, the inventors found that if the filter capacitor C1 is connected to the output end of the rectifier circuit, it is necessary to select a capacitor with a rated voltage greater than the output voltage of the rectifier circuit, and the required capacitor rated voltage is higher. If the filter capacitor C1 is connected to the end of the current limiting resistor (that is, one end of the resistor R11), although a capacitor with a lower rated voltage can be selected, the primary current of the isolation optocoupler OP1 near the zero point of the pulsating DC voltage output by the rectifier circuit will be too small, resulting in the isolation optocoupler OP1 being unable to conduct. Therefore, the filter capacitor C1 is connected to the middle position of the current limiting resistor branch, and a capacitor with a lower rated voltage can be selected, and a smooth DC voltage with an amplitude of half the peak voltage of the filter output can be obtained, ensuring that the isolation optocoupler OP1 is reliably conducted.

[0045] Reference Figure 2 In an exemplary embodiment of the present disclosure, the contactor state detection circuit further includes:

[0046] An XOR gate circuit, wherein the first input end of the XOR gate circuit is connected to the control end of the contactor, the second input end of the XOR gate circuit is connected to the second end of the normally open contact of the relay K1, and the output end of the XOR gate circuit is connected to the first signal input end of the controller.

[0047] In this embodiment, an XOR gate circuit U5 can be set between the second end of the normally open contact of the relay K1 and the first signal input end of the controller. When the control end of the contactor and the second end of the normally open contact of the relay K1 are both at a high level, it indicates that the contactor is in a normally closed state, and the XOR gate circuit outputs a low-level signal at this time; when the control end of the contactor and the second end of the normally open contact of the relay K1 are both at a low level, it indicates that the contactor is in a normally disconnected state, and the XOR gate circuit also outputs a low-level signal at this time; when the control end of the contactor and the second end of the normally open contact of the relay K1 are inconsistent in level, it indicates that the action state of the contactor is inconsistent with the control signal, and the action of the contactor is abnormal. At this time, the XOR gate circuit outputs a high-level signal to the first signal input end of the controller, and the controller determines that the contactor is faulty when receiving the high-level signal.

[0048] It can be concluded from the above that the setting of the XOR gate circuit in this embodiment realizes the hardware detection of the contactor fault state, which is helpful to reduce the burden on the controller.

[0049] Reference Figure 3 In an exemplary embodiment of the present disclosure, the contactor state detection circuit further includes a NOT gate circuit, an AND gate circuit, a resistor R20 and a capacitor C2.

[0050] The control signal of the contactor is connected to the first input terminal of the AND gate circuit. The second terminal of the normally open contact of the relay K1 is connected to the second input terminal of the AND gate circuit through the NOT gate circuit. The output terminal of the AND gate circuit is connected to the first terminal of the capacitor C2 through the resistor R20. The second terminal of the capacitor C2 is grounded.

[0051] The controller is configured to read the terminal voltage of the capacitor C2 and determine the action time of the contactor based on the terminal voltage of the capacitor C2.

[0052] In this embodiment, the contactor is mainly composed of an electromagnetic mechanism, a contact system and an arc extinguishing device. When the control signal acts on the electromagnetic mechanism, a magnetic field is generated in the coil, which attracts the armature to move, thereby driving the contacts to close or open. This process takes a certain amount of time, and the aging performance of the electromagnetic mechanism will increase the action delay of the contactor.

[0053] Taking the contactor's closing delay time as an example, this embodiment uses the moment when the second end of the normally open contact of relay K1 jumps from a low level to a high level as the contactor's closing time. By calculating the time difference between the moment when the contactor's control signal is issued and the moment when the contactor is closed, the contactor's action time is obtained.

[0054] Specifically, the contactor's control signal CTRL is connected to the first input of an AND gate U3, and the second terminal DO2 of the normally open contact of relay K1 is connected to the second input of the AND gate U3 via a NOT gate U2. When the contactor's control signal CTRL is high and the contactor is not closed, the second terminal of the normally open contact of relay K1 is low. This signal is converted to a high level by the NOT gate U2 and connected to the second input of the AND gate U3. The AND gate U3 outputs a high level signal, and the output of the AND gate U3 charges capacitor C2, increasing the voltage of capacitor C2. After the contactor is closed, the second terminal of the normally open contact of relay K1 is high. This signal is converted to a low level by the NOT gate U2 and connected to the second input of the AND gate U3. The AND gate U3 outputs a low level signal, and capacitor C2 stops charging. Therefore, by detecting the terminal voltage UC2 of capacitor C2, the time difference between the moment the contactor's control signal is issued and the moment the contactor closes, that is, the contactor's actuation time, can be obtained. If the contactor's actuation time exceeds the set value, it indicates that the contactor has an abnormality. The corresponding relationship between the contactor control signal CTRL, the second terminal DO2 of the normally open contact of the relay K1, the output terminal signal DO2' of the NOT gate circuit U2 and the terminal voltage UC2 of the capacitor C2 is as follows: Figure 4 shown.

[0055] It can be concluded from the above that the arrangement of the NOT gate circuit U2, the AND gate circuit U3, the resistor R20 and the capacitor C2 in this embodiment realizes the automatic detection of the contactor contact action time and can timely detect abnormalities of the electromagnetic mechanism in the contactor.

[0056] Reference Figure 3 In an exemplary embodiment of the present disclosure, the contactor state detection circuit further includes an operational amplifier U4, wherein the non-inverting input terminal of the operational amplifier U4 is connected to the first end of the capacitor C2, the output terminal of the operational amplifier U4 is feedback-connected to the inverting input terminal of the operational amplifier U4, and the output terminal of the operational amplifier U4 is connected to the AD channel of the controller.

[0057] In this embodiment, the operational amplifier U4 constitutes a voltage follower, which has the characteristics of high input impedance and low output impedance. It can prevent the signal from generating large losses in the output resistance of the previous stage, which is conducive to accurately transmitting the terminal voltage of the capacitor C2 to the AD channel of the controller.

[0058] In an exemplary embodiment of the present disclosure, the contactor state detection circuit further includes:

[0059] The temperature detection module is used to detect the contact temperature of the contactor, and the output end of the temperature detection module is connected to the second signal input end of the controller.

[0060] In this embodiment, during contactor operation, current flowing through the contacts generates heat. Excessively high temperatures can cause contactor failure, damage, or even safety incidents. To address this issue, this embodiment incorporates a temperature detection module that monitors contact temperature in real time. The output of the temperature detection module is connected to the controller's second signal input. When the detected contact temperature exceeds a preset safety threshold, the controller issues an alarm, prompting the operator to perform inspection and maintenance.

[0061] It can be concluded from the above that this embodiment can detect the contact temperature of the contactor in real time by providing the temperature detection module, and can promptly detect temperature anomalies of the contactor, thereby further improving the reliability of the contactor.

[0062] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present disclosure.

Claims

1. A contactor state detection circuit, characterized in that: Including rectifier circuit, switch tube Q1, relay K1 and controller, The input end of the rectifier circuit is used to be connected to the output end of the contactor, and the output end of the rectifier circuit is used to be connected to the control end of the switch tube Q1. The switch tube Q1 is used to control the power on or off of the coil of the relay K1. The first end of the normally open contact of the relay K1 is connected to the first power supply, and the second end of the normally open contact of the relay K1 is connected to the first signal input end of the controller. The controller is configured to: read a control signal of the contactor, compare a level of the control signal of the contactor with a level of the first signal input terminal, and determine a state detection result of the contactor based on the comparison result.

2. The contactor state detection circuit according to claim 1, characterized in that: A current limiting filter circuit is provided between the output end of the rectifier circuit and the switch tube Q1. The current limiting filter circuit includes a current limiting resistor branch consisting of a plurality of current limiting resistors connected in series, and a capacitor C1. The first end of the current-limiting resistor branch is connected to the output end of the rectifier circuit, the second end of the current-limiting resistor branch is used to be connected to the control end of the switch tube Q1, the first end of the capacitor C1 is connected to the midpoint of the current-limiting resistor branch, and the second end of the capacitor C1 is grounded; the midpoint of the current-limiting resistor branch is the connection point located in the middle of the connection points of multiple current-limiting resistors.

3. The contactor state detection circuit according to claim 2, characterized in that: An isolation optocoupler is provided between the current limiting filter circuit and the switch tube Q1.

4. The contactor state detection circuit according to claim 1, characterized in that: Also includes: An XOR gate circuit, wherein the first input end of the XOR gate circuit is connected to the control end of the contactor, the second input end of the XOR gate circuit is connected to the second end of the normally open contact of the relay K1, and the output end of the XOR gate circuit is connected to the first signal input end of the controller.

5. The contactor state detection circuit according to claim 1, characterized in that: It also includes a NOT gate circuit, an AND gate circuit, a resistor R20 and a capacitor C2. The control signal of the contactor is connected to the first input terminal of the AND gate circuit, the second terminal of the normally open contact of the relay K1 is connected to the second input terminal of the AND gate circuit through the NOT gate, the output terminal of the AND gate circuit is connected to the first terminal of the capacitor C2 through the resistor R20, and the second terminal of the capacitor C2 is grounded. The controller is configured to read the terminal voltage of the capacitor C2 and determine the action time of the contactor based on the terminal voltage of the capacitor C2.

6. The contactor state detection circuit according to claim 5, characterized in that: It also includes an operational amplifier U4, the non-inverting input terminal of the operational amplifier U4 is connected to the first end of the capacitor C2, the output terminal of the operational amplifier U4 is feedback-connected to the inverting input terminal of the operational amplifier U4, and the output terminal of the operational amplifier U4 is connected to the AD channel of the controller.

7. The contactor state detection circuit according to claim 1, characterized in that: Also includes: The temperature detection module is used to detect the contact temperature of the contactor, and the output end of the temperature detection module is connected to the second signal input end of the controller.

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