Coil self-test circuits, contactors and devices

Abstract

A coil self-detection circuit, a contactor and equipment, wherein the coil self-detection circuit comprises a central control circuit, a controllable switch, an action coil circuit, a voltage signal sampling circuit and a current signal sampling unit, wherein the central control circuit is respectively connected to the controllable switch, the voltage signal sampling circuit and the current signal sampling unit; when the set conditions for the action coil to act are met, the central control circuit controls the controllable switch to be turned on to cause the action coil to act, and when the set conditions for the action coil to act are not met, the central control circuit periodically sends a pulse signal to control the controllable switch to work, so that current flows through the action coil but the coil does not act; the central control circuit collects the current signal flowing through the coil through the current signal sampling unit, and if the collected current signal is lower than a preset low value, then the action coil has an open circuit fault; if the collected current signal is higher than a preset high value, then the action coil has a short circuit fault, thereby realizing self-detection of the coil.

Description

Technical Field

[0001] The invention relates to the field of low-voltage electrical appliances, contactors and circuit breakers, and in particular to a coil self-detection circuit. Background Art

[0002] With the development of intelligent contactor and circuit breaker accessory products, the self-checking capability of the electromagnetic system composed of the main part of this type of product, the action coil and the iron core, has also been put forward. Most of the existing products of this type have simple functions and no self-checking function for the action coil. When the coil winding has a circuit break or short circuit fault, the product cannot effectively judge and alarm, and cannot realize intelligent detection. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the prior art and provide a coil self-detection circuit, a contactor and a device.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A coil self-detection circuit comprises a central control circuit, a controllable switch and an action coil circuit, wherein the controllable switch element is connected in series to a power supply circuit of the coil, and further comprises a voltage signal sampling circuit and a current signal sampling unit, wherein the central control circuit is connected to the controllable switch, the voltage signal sampling circuit and the current signal sampling unit respectively; when the set conditions for the action coil to act are met, the central control circuit controls the controllable switch to be turned on to cause the action coil to act, and when the set conditions for the action coil to act are not met, the central control circuit periodically sends a pulse signal to control the controllable switch to work, so that current flows through the action coil but the coil does not act; the central control circuit collects a current signal flowing through the coil through the current signal sampling unit, and if the collected current signal is lower than a preset low value, then an open circuit fault occurs in the action coil; if the collected current signal is higher than a preset high value, then a short circuit fault occurs in the action coil.

[0006] Preferably, the central control circuit collects the voltage signal of the power supply through the voltage signal sampling circuit. When the voltage signal collected by the central control circuit is within a preset range, it is considered that the set conditions for the action coil to act are met; otherwise, it is considered that the set conditions for the action coil to act are not met.

[0007] Preferably, it also includes an alarm circuit connected to the central control circuit, and when the central control circuit detects that the action coil has a circuit breakage fault or a short circuit fault, an alarm is sounded through the alarm circuit.

[0008] Preferably, a signal conditioning circuit is also included, and the signal conditioning circuit is connected between the current signal sampling unit and the central control circuit.

[0009] Preferably, it also includes a driving circuit, and the central control circuit is connected to the controllable switch via the driving circuit.

[0010] Preferably, it also includes an EMC / EMI circuit, a rectifier circuit and a buck-stabilizing circuit; the input end of the EMC / EMI circuit is used to connect to an AC / DC power supply, the output end of the EMC / EMI circuit is connected to the rectifier circuit, the output end of the rectifier circuit is connected to the central control circuit and the drive circuit via the buck-stabilizing circuit, the input end of the voltage signal sampling circuit is connected to the EMC / EMI circuit, and the output end of the voltage signal sampling circuit is connected to the central control circuit.

[0011] Preferably, the controllable switch includes a MOS tube or an IGBT or a triode or a relay; the current signal sampling unit includes a resistor, or a current transformer or a Hall element or a manganese-copper shunt; and the central control circuit includes a single-chip microcomputer or a microprocessor MCU.

[0012] Preferably, there are two groups of action coils, controllable switches and current signal sampling units, namely a first action coil and a second action coil, a first controllable switch and a second controllable switch, and a first current signal sampling unit and a second current signal sampling unit; the central control circuit controls the on and off of the power supply circuit of the first action coil through the first controllable switch, and controls the on and off of the power supply circuit of the second action coil through the second controllable switch. The central control circuit collects the current signal of the first action coil through the first current signal sampling unit, and collects the current signal of the second action coil through the second current signal sampling unit. The central control circuit can detect open circuit faults and short circuit faults of any group of action coils.

[0013] The present invention further provides a contactor, comprising the coil self-detection circuit of the present invention.

[0014] The present invention also provides a device, comprising the coil self-detection circuit of the present invention.

[0015] The coil self-detection circuit of the present invention collects the current signal of the action coil to determine whether the action coil has a circuit break fault or a short circuit fault, thereby realizing coil self-detection. Moreover, when the set conditions for the action coil to operate are not met, a pulse signal is still sent out at regular intervals to control the operation of the controllable switch, so that current flows through the action coil but the coil does not operate. The coil self-detection can still be performed, so that an alarm prompt can be given in advance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a principle block diagram of the coil self-detection circuit of the present invention;

[0017] Figure 2 is a flow chart of the coil self-test method of the present invention;

[0018] Figure 3 1 is a circuit block diagram of a first embodiment of a coil self-detection circuit of the present invention;

[0019] Figure 4 1 is a circuit block diagram of a second embodiment of a coil self-detection circuit of the present invention;

[0020] Figure 5 It is a circuit block diagram of the third embodiment of the coil self-detection circuit of the present invention. DETAILED DESCRIPTION

[0021] The following is combined with Figures 1 to 5 The given embodiments further illustrate the specific implementation of the coil self-detection circuit of the present invention. The coil self-detection circuit of the present invention is not limited to the description of the following embodiments.

[0022] like Figure 1 As shown, a schematic diagram of a coil self-detection circuit of the present invention includes a central control circuit, a controllable switch and an action coil circuit, the controllable switch element is connected in series on the power supply circuit of the coil, and also includes a voltage signal sampling circuit and a current signal sampling unit, the central control circuit is connected to the controllable switch, the voltage signal sampling circuit and the current signal sampling unit respectively; the central control circuit collects the voltage signal of the power supply through the voltage signal sampling circuit, when the set conditions for the action coil to act are met, the central control circuit controls the controllable switch to turn on to make the action coil act, when the set conditions for the action coil to act are not met, the central control circuit regularly sends a pulse signal to control the controllable switch to work, so that current flows through the action coil but the coil does not act; the central control circuit collects the current signal flowing through the coil through the current signal sampling unit, if the collected current signal is lower than the preset low value, the action coil has a circuit breaker fault.

[0023] The coil self-detection circuit of the present invention collects the current signal of the action coil to determine whether the action coil has a circuit break fault or a short circuit fault, thereby realizing coil self-detection. Moreover, when the set conditions for the action coil to operate are not met, a pulse signal is still sent out at regular intervals to control the operation of the controllable switch, so that current flows through the action coil but the coil does not operate. The coil self-detection can still be performed, so that an alarm prompt can be given in advance.

[0024] The central control circuit of this embodiment includes a single chip microcomputer or a microprocessor MCU. Figure 2 As shown, the single chip microcomputer or microprocessor MCU executes Figure 2The steps are described to realize coil self-test. After power-on, the system power-on self-test is first performed. After the self-test passes, the coil self-test can be performed regularly. During the coil self-test, it is first determined whether the set conditions for the action of the action coil are met. For example, in this embodiment, the voltage signal is collected by the voltage signal sampling circuit to determine whether the collected voltage signal meets the set conditions. If the voltage signal collected by the control circuit is within the preset range, it is considered that the voltage signal meets the set conditions, otherwise it is considered that the voltage signal does not meet the set conditions. If the voltage signal is within the preset range, the controllable switch is controlled to conduct the coil power supply circuit, so that the action coil is actuated, such as triggering the coil's moving and static iron cores to attract, or the moving iron core drives the ejector to pop out, etc., to achieve the function of the corresponding product; if the voltage signal is not within the preset range, the controllable switch is controlled to conduct for a short time by sending a pulse signal at a fixed time, so that the action coil flows through the current and does not trigger the coil to act; then the current signal of the coil power supply circuit is collected by the current signal sampling unit to determine whether the collected current is within the preset range. If the collected current signal is higher than the preset high value, the action coil has a short circuit fault. If the collected current signal is lower than the preset low value, the action coil has an open circuit fault. When a short circuit or open circuit fault is detected in the action coil, an alarm circuit will be used to warn the user and the upper-level system. Of course, the coil self-detection circuit also includes the necessary power supply circuit, and can also include corresponding rectification, step-down and filtering circuits. In this embodiment, judging whether the set condition of the action coil is satisfied refers to whether the collected voltage signal is within a preset range; of course, according to the actual situation, it does not only refer to the voltage signal, for example, it can also include remote control signals and / or timing trigger signals that can put the coil in a working state. On the contrary, when any of the above signals does not meet the set condition, it is considered that the set condition of the action coil is not satisfied.

[0025] Of course, the central control circuit can also be implemented through a hardware circuit, such as a hardware circuit including a comparator and a logic circuit, which can detect whether a short circuit or open circuit fault occurs in the action coil based on comparison and give an alarm through an alarm circuit.

[0026] like Figure 3 As shown, the first embodiment of the coil self-detection circuit of the present invention includes an EMC / EMI circuit, a rectifier circuit, a buck stabilization circuit, a voltage signal sampling circuit, a central control circuit, a drive circuit, an alarm circuit, a signal conditioning circuit, a current signal sampling unit, a controllable switch and an action coil circuit.

[0027] The input end of the EMC / EMI circuit is used to connect to the AC and DC power supply, the output end of the EMC / EMI circuit is connected to the rectifier circuit, the output end of the rectifier circuit is connected to the central control circuit and the drive circuit via the step-down voltage stabilization circuit to supply power to the central control circuit and the drive circuit, the rectifier circuit is connected to the action coil to supply power to the action coil, the controllable switch is connected in series in the power supply circuit of the action coil, the central control circuit is connected to the controllable switch via the drive circuit to drive the central control switch to turn on and off to supply power to the action coil; the input end of the voltage signal sampling circuit is connected to the EMC / EMI circuit, the output end of the voltage signal sampling circuit is connected to the central control circuit to transmit the collected power supply voltage signal to the central control circuit; the current signal sampling unit is connected to the power supply circuit of the action coil, the current signal sampling unit transmits the collected current signal to the central control circuit via the signal conditioning circuit; the central control circuit is connected to the alarm circuit.

[0028] The EMC / EMI circuit, the rectifier circuit and the buck regulator circuit constitute a power supply circuit, which provides power and protection for the coil self-detection circuit. The EMC / EMI circuit isolates the external electromagnetic interference from the internal and external electromagnetic interference during its own operation, thereby improving the stability and reliability of the system. The rectifier circuit rectifies the external AC power supply or DC power supply into a DC power supply with a fixed current direction, achieving universal AC and DC, and there is no need to distinguish between positive and negative poles when DC is input. The buck regulator circuit steps down and stabilizes the voltage input by the rectifier circuit into a low-voltage signal to power other modules in the circuit.

[0029] The central control circuit includes a single-chip computer or a microprocessor MCU. The central control circuit samples and processes the voltage signal in real time through a voltage signal sampling circuit, and determines whether the action condition is met. The central control circuit outputs different pulse signals according to the voltage signal, turns on the controllable switch, and flows current through the action coil. The current flowing through the action coil is collected by the current signal sampling unit to determine whether there is a fault in the action coil. When the voltage signal meets the action condition, the central control circuit outputs a long-term continuous conduction signal to trigger the iron core action in the action coil, or the output pulse signal has a large duty cycle to trigger the iron core action in the action coil. When the voltage signal does not meet the action condition, the central control circuit outputs a pulse signal with a small duty cycle and a short duration, which will not cause the action coil to malfunction, but the coil can be self-checked. When the central control circuit detects that the sampled voltage signal is within the preset range through the voltage signal sampling circuit, the controllable switch is driven by the driving circuit to realize the conduction of the current in the action coil to realize the function of the product. At this time, the current loop composed of the action coil, the controllable switch and the rectifier circuit is in the conducting state; the central control circuit samples the current signal flowing through the current loop through the signal conditioning circuit and the current signal sampling unit to determine whether the current size is within the preset range. If the current value of the sampled current is lower than the preset low value, the action coil has an open circuit fault; if the current value of the sampled current is higher than the preset high value, the action coil has a short circuit fault. At the same time, if the sampled voltage signal is not within the preset range, the central control circuit drives the controllable switch through the driving circuit to realize the shutoff of the current in the action coil, but the central control circuit will also send out a pulse signal at a fixed time, and send out a pulse signal through the driving circuit to drive the controllable switch to work, so that the action coil flows through the current but the coil does not move. The pulse width of this pulse signal is short and will not cause the action coil to malfunction. During the operation of the pulse signal, the central control circuit samples the current signal flowing through the current loop composed of the action coil, the controllable switch and the rectifier circuit through the signal conditioning circuit and the current signal sampling unit to determine whether the current size is within a preset range. If the current value of the sampled current is lower than the preset low value, the action coil has an open circuit fault; if the current value of the sampled current is higher than the preset high value, the action coil has a short circuit fault. When the central control circuit detects a short circuit or open circuit fault in the action coil, it will alert the user and the upper-level system through the alarm circuit.

[0030] The voltage signal sampling circuit collects the voltage signal of the input power supply, and the voltage signal sampling circuit can use a voltage divider circuit including a voltage divider resistor. The current signal sampling unit collects the current signal flowing through the action coil, and the current signal sampling unit includes a resistor, a current transformer, a Hall element, a manganese copper shunt, etc. The signal conditioning circuit filters the current signal collected by the current signal sampling unit and transmits it to the central control circuit. The controllable switch can be a semiconductor switch such as a MOS tube, an IGBT, or a triode, or a mechanical switch such as a relay. The action coil can be a single coil or two groups of coils, wherein the two groups of coils can be used in parallel or in series. The alarm circuit can include an indicator light, and / or a buzzer, and or a display screen, and or notify the host computer through the network, etc.

[0031] like Figure 4 As shown, the second embodiment of the coil self-detection circuit of the present invention is basically the same as the first embodiment, except that the current signal sampling unit includes a sampling resistor R1, and current sampling is achieved through the sampling resistor R1.

[0032] like Figure 5 As shown, the third embodiment of the coil self-detection circuit of the present invention. The third embodiment is basically the same as the first embodiment, except that there are two groups of action coils, such as Figure 5 As shown, there are two groups of action coils, controllable switches and current signal sampling units. They are the first action coil and the second action coil, the first controllable switch and the second controllable switch, and the first current signal sampling unit and the second current signal sampling unit; the central control circuit controls the on and off of the power supply circuit of the first action coil through the drive circuit and the first controllable switch, and controls the on and off of the power supply circuit of the second action coil through the drive circuit and the second controllable switch; the central control circuit collects the current signal flowing through the first action coil through the first current signal sampling unit, and collects the current signal flowing through the second action coil through the second current signal sampling unit. The central control circuit can detect the open circuit fault and short circuit fault of any group of action coils. The self-check method of the two groups of action coils is the same as that of only one group, except that the central control circuit needs to self-check the two groups of action coils at the same time. When the central control circuit detects that any group of action coils has an open circuit fault or a short circuit fault, an alarm is given through the alarm circuit.

[0033] The coil self-detection circuit of Example 3 is generally used in contactors. Unlike products with only one set of action coils, the electromagnetic system composed of the coil and the iron core uses different action coil windings in the attracted state and the maintained state. For example, in the startup phase of the contactor, a large current is used to activate the first action coil to drive the moving contact and the static contact of the contactor to close. After the moving contact and the static contact are closed, a small current is used to activate the second action coil to maintain the closure of the moving contact and the static contact, and the first action coil is disconnected at the same time to reduce power consumption.

[0034] The present invention also provides a contactor, which includes the coil self-detection circuit of the present invention, preferably includes the coil self-detection circuit of embodiment three, which is used to perform self-detection on two groups of action coils. When the central control circuit detects that any group of action coils has a circuit breakage fault or a short circuit fault, an alarm is issued in advance to eliminate the fault of the contactor in advance.

[0035] The present invention also provides a device, which includes the coil self-detection circuit of the present invention, such as a contactor, a circuit breaker, etc.

[0036] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A coil self-detection circuit, comprising a central control circuit, a controllable switch and an action coil circuit, wherein the controllable switch element is connected in series to the power supply circuit of the coil, and is characterized in that: It also includes a voltage signal sampling circuit and a current signal sampling unit, and the central control circuit is connected to the controllable switch, the voltage signal sampling circuit and the current signal sampling unit respectively; When the set conditions for the action coil to operate are met, the central control circuit controls the controllable switch to conduct to make the action coil operate. When the set conditions for the action coil to operate are not met, the central control circuit periodically sends a pulse signal to control the controllable switch to operate, so that current flows through the action coil but the coil does not operate. The central control circuit collects the current signal flowing through the coil through the current signal sampling unit. If the collected current signal is lower than a preset low value, the action coil has an open circuit fault; if the collected current signal is higher than a preset high value, the action coil has a short circuit fault.

2. The coil self-detection circuit according to claim 1, characterized in that: The central control circuit collects the voltage signal of the power supply through the voltage signal sampling circuit. When the voltage signal collected by the central control circuit is within the preset range, it is considered that the set conditions for the action coil action are met. Otherwise, it is considered that the set conditions for the action coil action are not met.

3. The coil self-detection circuit according to claim 1, characterized in that: It also includes an alarm circuit connected to the central control circuit. When the central control circuit detects that the action coil has a circuit breakage fault or a short circuit fault, an alarm is sounded through the alarm circuit.

4. The coil self-detection circuit according to claim 1, characterized in that: It also includes a signal conditioning circuit, which is connected between the current signal sampling unit and the central control circuit.

5. The coil self-detection circuit according to claim 1, characterized in that: It also includes a driving circuit, through which the central control circuit is connected to the controllable switch.

6. The coil self-detection circuit according to any one of claims 1 to 5, characterized in that: It also includes an EMC / EMI circuit, a rectifier circuit and a buck-stabilizing circuit; the input end of the EMC / EMI circuit is used to connect to an AC / DC power supply, the output end of the EMC / EMI circuit is connected to the rectifier circuit, the output end of the rectifier circuit is connected to the central control circuit and the drive circuit via the buck-stabilizing circuit, the input end of the voltage signal sampling circuit is connected to the EMC / EMI circuit, and the output end of the voltage signal sampling circuit is connected to the central control circuit.

7. The coil self-detection circuit according to claim 1, characterized in that: The controllable switch includes a MOS tube or an IGBT or a triode or a relay; the current signal sampling unit includes a resistor, a current transformer, a Hall element or a manganese-copper shunt; and the central control circuit includes a single-chip microcomputer or a microprocessor MCU.

8. The coil self-detection circuit according to claim 1, characterized in that: There are two groups of action coils, controllable switches and current signal sampling units, namely the first action coil and the second action coil, the first controllable switch and the second controllable switch, and the first current signal sampling unit and the second current signal sampling unit; the central control circuit controls the on and off of the power supply circuit of the first action coil through the first controllable switch, and controls the on and off of the power supply circuit of the second action coil through the second controllable switch. The central control circuit collects the current signal of the first action coil through the first current signal sampling unit, and collects the current signal of the second action coil through the second current signal sampling unit. The central control circuit can detect the open circuit fault and short circuit fault of any group of action coils.

9. A contactor, characterized in that: It comprises the coil self-detection circuit described in any one of claims 1-8.

10. A device, characterized in that: It comprises the coil self-detection circuit described in any one of claims 1-8.

Images