WO2019153834A1

WO2019153834A1 - Contactor energy saving test circuit

Info

Publication number: WO2019153834A1
Application number: PCT/CN2018/116948
Authority: WO
Inventors: 苏俊熙
Original assignee: 广州金升阳科技有限公司; 深圳南云微电子有限公司
Priority date: 2018-02-11
Filing date: 2018-11-22
Publication date: 2019-08-15
Also published as: CN108387810A; CN108387810B

Abstract

A contactor energy saving test circuit. A rectifier bridge (DB1) and a main power circuit form a contactor energy saving circuit, and a rectifier circuit (DB2), a sampling circuit, and a threshold comparison circuit are further added thereto. The threshold comparison circuit has a first reference (VTH1) and a second reference (VTH2). When a peak voltage of an output end signal (VT) of the sampling circuit is greater than the first reference (VTH1), the main power circuit is controlled to operate, and a contactor is attracted; when a voltage of the output end signal (VT) of the sampling circuit is lower than the second reference (VTH2), the main power circuit is controlled to be turned off, and the contactor is released. When an input voltage is an alternating current voltage, the peak voltage of the output end signal (VT) of the sampling circuit is equal to a voltage of the output end signal (VT) of the sampling circuit when the input voltage is a direct current voltage, such that the same voltage point triggers the contactor to operate, and an attraction voltage point and a release voltage point of a wide input voltage contactor are consistent regardless of whether the input voltage is an alternating current or a direct current input voltage. In addition, the circuit is easy to use. The invention ensures compatibility between alternating current and direct current contactor energy saving products and reduces production and inventory pressure of a manufacturer.

Description

Contactor power saver detection circuit

Technical field

The present invention relates to the field of AC contactors, and in particular to a contactor power saver detection circuit.

Background technique

The traditional contactor operating system consists of a coil, a static iron core, an armature and a reaction spring. When the contactor coil is energized, a suction force is generated between the static iron core and the armature. When the suction force is greater than the spring reaction force, the armature is attracted to the static iron core until it contacts the static iron core, and the main contact is closed. This process is called suction. Process. The process of continuously energizing the coil, keeping the armature in contact with the static iron core, and maintaining the main contact in a closed state is called a holding process. When the current in the coil is reduced or interrupted, the suction force of the static iron core to the armature is reduced. When the suction force is less than the spring reaction force, the armature returns to the open position, and the main contacts are separated. This process is called a release process. From an electrical point of view, the contactor coil can be equivalent to an inductor with a certain internal resistance.

Conventional contactors have a narrow input voltage range, and the same current-carrying contactor is divided into multiple specifications according to the operating voltage of the coil. Take the common CJ20 contactor on the market as an example. The voltage specifications of the general coil are shown in Table 1. In order to apply different input voltages, multiple specifications are required.

Table 1 coil operating voltage rating

	线圈操作电压额定值U _S Coil operating voltage rating U _S
交流输入AC input	36V _AC、127V _AC、220V _AC、380V _AC 36V _AC , 127V _AC , 220V _AC , 380V _AC
直流输入DC input	48V _DC、110V _DC、220V _DC 48V _DC , 110V _DC , 220V _DC

At the same time, the operating voltage range of the coil is also relatively narrow. The general pull-in voltage ranges from 85% to 110% U _S and the release voltage is 20% to 75% U _S . As can be seen from the above data, the conventional contactor coil has a narrow working range and many specifications.

The narrow working range of the conventional contactor is caused by the current of the contactor coil following the change of the input voltage. When the input voltage is high, the current is large, the coil is easy to generate heat and damage; when the input voltage is low, the suction is small and the suction is unreliable. In recent years, contactor technology with PWM control has also become popular. With PWM control technology, the coil current can be constant over a wide range, and the wide voltage ratio (highest input voltage / lowest input voltage) can reach 9. As a simple example, as long as the coil design is appropriate, the coil current can be constant over an input voltage range of 30V to 270V. Therefore, some contactor manufacturers are planning to introduce products with wide input range voltage. The normal working voltage range of the coil is 80V~275V, the release voltage is 40~60V, and the input AC and DC are required, whether it is AC voltage or DC voltage. The input has the same threshold for the pull-in and release. Similar to such a wide input voltage contactor product, a voltage detection circuit is generally required to detect the input voltage and control the pull-in and release of the contactor.

However, there is a problem with AC and DC. When the effective voltage is constant, the peak value of the AC and DC voltage is different. For example, if the effective value is 80V AC, the peak value is 113V. In the case of AC/DC universal, if simple voltage sampling is used and the threshold is compared, then the AC input will be triggered at a lower voltage, causing the AC input and DC input operating voltages to be inconsistent.

Summary of the invention

In view of the above, the technical problem to be solved by the present invention is to provide a contactor power saver detecting circuit, which can achieve the same operating voltage of the contactor under the conditions of AC input and DC input.

In order to achieve the above object, the technical solution of the present invention is as follows:

A contactor power saver detecting circuit comprises a first rectifier bridge and a main power circuit in an existing contactor power saver for controlling current of the contactor coil; further comprising a second rectifier bridge, a sampling circuit and a threshold comparison circuit; The AC input terminals of the first rectifier bridge and the second rectifier bridge are connected in parallel with the input voltage, the positive output end of the first rectifier bridge is connected to the main power circuit, and the positive output end of the second rectifier bridge is connected to the input end of the sampling circuit. The negative output end of the first rectifier bridge is common to the negative output end of the second rectifier bridge, the output end of the sampling circuit is connected to the input end of the threshold comparison circuit, and the output end of the threshold comparison circuit is connected to the main power circuit; the threshold comparison circuit is internally There are reference one and reference two. When the peak voltage of the output signal of the sampling circuit is greater than the reference one, the threshold comparison circuit outputs a control signal to control the operation of the main power circuit, and the contactor pulls in; when the output signal of the sampling circuit has a valley voltage less than the reference two When the threshold comparison circuit outputs a control signal to control the main power circuit to be turned off, the contactor is released; when the input voltage is AC, the sampling is performed. The output of the signal output terminal voltage and the input voltage peak signal voltage sampling circuit is equal to the DC.

As an improvement of the above scheme, a Zener diode can be connected in parallel with the output end of the sampling circuit, the cathode of the Zener diode is connected to the output end of the sampling circuit, and the anode of the Zener diode is grounded.

As a first specific implementation of the sampling circuit, the resistor R1, the resistor R2 and the capacitor C1 are formed. The two ends of the resistor R1 and the resistor R2 are connected to form an input end of the sampling circuit, and the capacitor C1 has one end and a resistor R1 and a resistor R2. The connection points are connected, and the other end of the capacitor C1 is grounded.

As a modification of the first embodiment of the sampling circuit, the Zener diode Z1 is further connected, and the Zener diode Z1 is connected in parallel across C1. The cathode of the Zener diode Z1 is connected to the connection point of the resistor R1, the resistor R2 and the capacitor C1. The anode of Zener diode Z1 is grounded.

As a second specific implementation manner of the sampling circuit, the inductor L1, the resistor R3 and the resistor R4 are formed. The two ends of the inductor L1, the resistor R3 and the resistor R4 are connected in series to form an input end of the sampling circuit, and the resistor R3 and the resistor R4. The connection point is the output of the sampling circuit.

As a modification of the second embodiment of the sampling circuit, the Zener diode Z1 is connected, and the Zener diode Z1 is connected in parallel across the resistor R4. The cathode of the Zener diode Z1 is connected to the connection point of the resistor R3 and the resistor R4. The anode of the voltage diode Z1 is grounded.

Another technical solution that is the same inventive concept of the present application is as follows:

A contactor power saver detecting circuit comprises a first rectifier bridge and a main power circuit for controlling current of the contactor coil; further comprising a first diode, a second diode, a sampling circuit and a threshold comparison circuit; The input ends of a rectifier bridge are respectively connected to the anodes of the first diode and the second diode, and the positive output end of the first rectifier bridge is connected to the main power circuit, and the negative output end of the first rectifier bridge is grounded, the first two poles The tube is connected to the cathode of the second diode and grounded through the input end of the sampling circuit. The output end of the sampling circuit is connected to the input end of the threshold comparison circuit, and the output end of the threshold comparison circuit is connected to the main power circuit; the threshold comparison circuit is internally There are reference one and reference two. When the peak voltage of the output signal of the sampling circuit is greater than the reference one, the threshold comparison circuit outputs a control signal to control the operation of the main power circuit, and the contactor pulls in; when the output signal value of the sampling circuit is less than the reference value Second, the threshold comparison circuit outputs a control signal to control the main power circuit to be turned off, and the contactor is released; when the input voltage is an output signal of the sampling circuit of the alternating current Equal to the peak voltage signal on the output voltage and the input voltage sampling circuit is DC.

As an improvement of the above scheme, a Zener diode can also be connected in parallel with the output end of the sampling circuit, the cathode of the Zener diode is connected to the output end of the sampling circuit, and the anode of the Zener diode is grounded.

As a first specific implementation of the sampling circuit, the resistor R1, the resistor R2 and the capacitor C1 are formed. The resistor R1 and the resistor R2 are connected in series, and one end of the resistor R1 and the resistor R2 are connected in series to connect the first diode and the second diode. The cathode connection point of the tube, the other end of the resistor R1 and the resistor R2 connected in series is grounded, one end of the capacitor C1 is connected to the connection point of the resistor R1 and the resistor R2, and the other end of the capacitor C1 is grounded.

As a second specific implementation manner of the sampling circuit, the inductor L1, the resistor R3 and the resistor R4 are formed. The cathode connection points of the first diode and the second diode are grounded through the inductor L1, the resistor R3 and the resistor R4. The connection point of the resistor R3 and the resistor R4 is the output end of the sampling circuit.

As a modification of the first embodiment of the sampling circuit, the Zener diode Z1 is connected, and the Zener diode Z1 is connected in parallel across the resistor R4. The cathode of the Zener diode Z1 is connected to the connection point of the resistor R3 and the resistor R4. The anode of the voltage diode Z1 is grounded.

The working principle of the invention is analyzed as follows:

The output signal of the sampling circuit is recorded as VT; the internal reference of the threshold comparison circuit is denoted by VTH1 and the reference second is denoted by VTH2.

When the peak voltage of the signal VT is greater than VTH1, the main power circuit is controlled to operate, and the contactor is closed; when the valley voltage of the signal VT is less than VTH2, the main power circuit is controlled to be closed, and the contactor is released.

The transfer function of the input and output of the sampling circuit is a function A(f) related to the frequency of the input signal. When the input voltage is DC, the gain of the input to output of the sampling circuit is denoted as A(0). When the input voltage is a power frequency 50 Hz signal, the rectified voltage fundamental frequency is 100 Hz, and the input-output gain of the sampling circuit is recorded as A (100).

The formula for rectifying the AC input voltage is:

Where U _E is the input voltage rms value. The V _IN-AC (t) is subjected to Fourier series expansion. The harmonic components above 200 Hz are already small. The components above 200 Hz can be ignored, and only the harmonic components and DC components of 100 Hz are retained. The formula is:

After the rectified AC bus voltage passes through the sampling circuit, the voltage formula of the signal VT is:

When AC input, the peak voltage of the signal VT is:

At DC input, the voltage of signal VT is:

VT _DC =U _E ·A(0)

The invention has the beneficial effects that: by selecting the sampling circuit parameters, setting appropriate A(0) and A(100), and letting VT _DC = VT _AC , the voltage effective value can be made the same AC and DC condition, the signal VT The peak voltage is the same, so that the voltage point that triggers the contactor action is the same, the wide input voltage contactor achieves the same purpose of attracting and releasing the voltage point under the AC and DC input voltage, and the circuit is simple and easy to use, thereby finally realizing the intersection. The versatility of DC contactor power saver products reduces the manufacturer's production and inventory pressure.

At the same time, after increasing the Zener diode Z1, the voltage of the signal VT can be limited. When the input voltage is low, the time after the input power is reduced, the voltage of the signal VT drops to the undervoltage threshold point, and the delay time of the shutdown can be reduced. .

DRAWINGS

Figure 1 is a schematic circuit diagram of the present invention;

Figure 2 is a schematic diagram of a first embodiment of the present invention;

3 is an equivalent circuit of a sampling circuit in the first embodiment of the present invention;

4 is a waveform of a signal VT at different input voltages according to the first embodiment of the present invention;

Figure 5 is a schematic diagram of a second embodiment of the present invention;

Figure 6 is a schematic diagram of a third embodiment of the present invention;

Figure 7 is a schematic diagram of a fourth embodiment of the present invention.

Detailed ways

1 is a circuit schematic diagram of the present invention. The present invention adds a rectifier circuit, a sampling circuit and a threshold comparison circuit, and a threshold comparison circuit based on the existing rectifier power saver circuit and the main power circuit. There are reference one and reference two inside. When the peak voltage of the output signal of the sampling circuit is greater than the reference one, the main power circuit is controlled to work, and the contactor is closed; when the signal value of the output end of the sampling circuit is less than the reference two, the main control The power circuit is turned off, and the contactor is released; when the input voltage is AC, the peak voltage of the output end of the sampling circuit is equal to the output voltage of the sampling circuit when the input voltage is DC, so that the voltage point of the trigger contactor is the same, and the wide input is realized. The voltage contactor has the same purpose of attracting and releasing voltage points under the condition of AC and DC input voltage, and the circuit is simple and easy to use, thereby finally realizing the universality of AC/DC contactor power saver products and reducing the production and inventory pressure of the manufacturer.

In order to make the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

First embodiment

2 is a schematic diagram of a first embodiment of the present invention. The general contactor power saver includes a rectifier bridge DB1 and a main power circuit for controlling the current of the contactor coil. The embodiment further includes a rectifier bridge DB2, a resistor R1, a resistor R2, a capacitor C1, and a threshold comparison circuit. The AC input terminal AC of the rectifier bridge DB1 and the rectifier bridge DB2 are connected in parallel with the input voltage, the positive output terminal VBUS1 of the rectifier bridge DB1 is connected to the main power circuit, and the negative output terminal of the rectifier bridge DB1 is connected to the ground. The positive output terminal VBUS2 of the rectifier bridge DB2 is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the resistor R2, and the connection point of the resistor R1 and the resistor R2 is connected as an output terminal to the threshold comparison circuit, and the resistor R2 is connected. The other end is connected to the negative output end of the rectifier bridge DB2 and grounded. The capacitor C1 is connected in parallel across the resistor R2, and the threshold comparison circuit is connected to the main power circuit.

The embodiment further includes a Zener diode Z1, and the Zener diode Z1 is connected in parallel across the C1. The cathode of the Zener diode Z1 is connected to the connection point of the resistor R1, the resistor R2 and the capacitor C1, and the anode of the Zener diode Z1 is grounded. .

The voltage at the junction of the resistor R1 and the resistor R2 is referred to as a signal VT, and the threshold comparison circuit has references VTH1 and VTH2 therein. When the peak voltage of the signal VT is greater than VTH1, the main power circuit is controlled to operate, and the contactor is closed; when the valley voltage of the signal VT is less than VTH2, the main power circuit is controlled to be closed, and the contactor is released.

The working principle of the present invention will be described below. The sampling circuit composed of the resistor R1, the resistor R2 and the capacitor C1 can be simplified by the Thevenin theorem, as shown in FIG. The equivalent relationship is as follows:

Among them, VBUS2 is the bus voltage after rectification. The transfer function of the voltage divider circuit composed of RD and C1 is:

among them,

f is the frequency of the input signal.

When the input voltage is DC, the gain of the sampling circuit is:

A _D (0)=1

When the input voltage is power frequency communication,

When the input is a DC voltage, the voltage of the signal VT is:

When the input is an AC voltage, the voltage peak of the signal VT is:

Through the appropriate values of resistor R1, resistor R2 and capacitor C1, VT _DC = VT _AC can be made, and finally, the voltages that are triggered at the DC input and the AC input are the same, achieving the universal effect of AC and DC.

The actual effect of the present invention will be described below using a specific set of data. Let the pull-in threshold compared with VT be 1.2V, the release threshold be 0.8V, R1=3MΩ, R2=50kΩ, C1=0.22uF, and the frequency of the bus voltage after rectification f=100Hz. Substituting the above formula, the trigger voltage points of the DC input and the AC input can be obtained, as shown in Table 2. As can be seen from the table, the AC and DC input conditions are in line with the requirements of the current new products. A more intuitive effect is shown in Figure 4, which shows the voltage value of the signal VT at different input voltages.

Table 2 Using the present invention, the trigger point when AC and DC input

	交流输入AC input	直流输入DC input
吸合电压Pull-in voltage	74V _AC 74V _AC	73V _DC 73V _DC
释放电压Release voltage	60V _AC 60V _AC	49V _DC 49V _DC

If the method of the present invention is not used, the main power circuit bus voltage VBUS2 is directly sampled, and the actual effect is shown in Table 3. Since the bus voltage of the main power is directly sampled, the voltage amplitude of the bus voltage is related to the power consumption of the bus capacitance and the main power circuit, which is an indeterminate value, and the difference between the AC and DC pull-in and release voltage points is too large.

Table 3 does not use the present invention, the trigger point when AC and DC input

	交流输入AC input	直流输入DC input
吸合电压Pull-in voltage	51V _AC 51V _AC	73V _DC 73V _DC
释放电压Release voltage	不确定uncertain	49V _DC 49V _DC

It can be known from the above principle analysis that the circuit of the present invention can make the AC and DC pull-in and release voltage points relatively consistent, and the circuit is simple and easy to use.

Second embodiment

FIG. 5 is a schematic diagram of a second embodiment of the present invention. The second embodiment differs from the first embodiment in that the sampling circuit is composed of an inductor L1, a resistor R3 and a resistor R4. The inductor L1, the resistor R3 and the resistor R4 are connected in series. The two terminals form the input end of the sampling circuit, and the connection point of the resistor R3 and the resistor R4 is the output end of the sampling circuit. The embodiment further includes a Zener diode Z1, and the Zener diode Z1 is connected in parallel across the resistor R4. The cathode of the Zener diode Z1 is connected to the connection point of the resistor R3 and the resistor R4, and the anode of the Zener diode Z1 is grounded.

The basic principle of the second embodiment is the same as that of the first embodiment. The sampling circuit composed of the inductor L1, the resistor R3 and the resistor R4 has a transfer function of:

When the input voltage is DC, the gain of the sampling circuit is:

When the input voltage is AC frequency, the gain of the sampling circuit is:

The same effect as in the first embodiment can be obtained by selecting the values of the appropriate inductance L1, resistance R3 and resistance R4.

Third embodiment

6 is a schematic diagram of a third embodiment of the present invention. The third embodiment is different from the first embodiment in that the rectifier bridge DB2 is replaced by a diode D1 and a diode D2, and the diode D1 and the diode D2 and the rectifier bridge DB1 are grounded therein. The diodes form a full-wave rectifier circuit. The connection relationship is that the anode of the diode D1 is connected to one end of the AC input AC of the rectifier bridge DB1, and the anode of the diode D2 is connected to the other end of the AC input AC of the rectifier bridge DB1. The cathode of the diode D1, the cathode of the diode D2 is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the resistor R2, and the connection point of the resistor R1 and the resistor R2 is connected as an output terminal to the threshold comparison circuit, and the other end of the resistor R2 Connected to the negative output of the rectifier bridge DB2 and grounded, the capacitor C1 is connected in parallel across the resistor R2, and the threshold comparison circuit is connected to the main power circuit. The embodiment further includes a Zener diode Z1, and the Zener diode Z1 is connected in parallel across C1. The cathode of the Zener diode Z1 is connected to the connection point of the resistor R1, the resistor R2 and the capacitor C1, and the anode of the Zener diode Z1 is grounded. .

Third, the principle of the embodiment is basically the same as that of the first embodiment. In the third embodiment, the diode D1, the diode D2, and the two diodes grounded in the rectifier bridge DB1 constitute DB2 in the first embodiment. The other partial circuits are the same as the first embodiment.

Fourth embodiment

FIG. 7 is a schematic diagram of a fourth embodiment of the present invention. The fourth embodiment is different from the second embodiment in that the rectifier bridge DB2 is replaced by a diode D1 and a diode D2, and the diode D1 and the diode D2 and the rectifier bridge DB1 are grounded therein. The diodes form a full-wave rectifier circuit. The connection relationship is: the anode of the diode D1 is connected to one end of the AC input AC of the rectifier bridge DB1, the anode of the diode D2 is connected to the other end of the AC input AC of the rectifier bridge DB1, and the cathode of the diode D1 and the cathode of the diode D2 are connected to one end of the resistor R1. The cathode connection point of the first diode and the second diode is grounded through the inductor L1, the resistor R3 and the resistor R4, and the connection point of the resistor R3 and the resistor R4 is the output end of the sampling circuit. The embodiment further includes a Zener diode Z1, and the Zener diode Z1 is connected in parallel across the resistor R4. The cathode of the Zener diode Z1 is connected to the connection point of the resistor R3 and the resistor R4, and the anode of the Zener diode Z1 is grounded.

The principle of the fourth embodiment is basically the same as that of the second embodiment. In the third embodiment, the diode D1, the diode D2, and the two diodes grounded in the rectifier bridge DB1 constitute DB2 in the second embodiment. The other partial circuits are the same as the first embodiment.

The above is only a preferred embodiment of the present invention, and it should be noted that the above-described preferred embodiments are not to be construed as limiting the scope of the invention, and the scope of the invention should be determined by the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and scope of the invention.

Claims

A contactor power saver detecting circuit includes a first rectifier bridge and a main power circuit for controlling current of the contactor coil; and further comprising: a second rectifier bridge, a sampling circuit and a threshold comparison circuit; and a first rectifier bridge And connected to the input voltage in parallel with the AC input end of the second rectifier bridge, the positive output end of the first rectifier bridge is connected to the main power circuit, and the positive output end of the second rectifier bridge is connected to the input end of the sampling circuit, the first rectifier bridge The negative output end is shared with the negative output end of the second rectifier bridge, the output end of the sampling circuit is connected to the input end of the threshold comparison circuit, and the output end of the threshold comparison circuit is connected to the main power circuit; the threshold comparison circuit has a reference one inside Benchmark 2, when the peak voltage of the output signal of the sampling circuit is greater than the reference one, the threshold comparison circuit outputs a control signal to control the operation of the main power circuit, and the contactor pulls in; when the output signal of the sampling circuit is lower than the reference two, the threshold is compared. The circuit output control signal controls the main power circuit to be turned off, and the contactor is released; the input voltage is the output of the sampling circuit when AC Equal to the output of the peak signal voltage to the input voltage signal sampling circuit is DC.
The contactor power saver detecting circuit according to claim 1, further comprising a Zener diode, wherein the cathode of the Zener diode is connected to the output end of the sampling circuit, and the anode of the Zener diode is grounded.
The contactor power saver detecting circuit according to claim 1, wherein the sampling circuit comprises a resistor R1, a resistor R2 and a capacitor C1, and the two ends of the resistor R1 and the resistor R2 are connected to form an input end of the sampling circuit, and the capacitor C1 One end is connected to the connection point of the resistor R1 and the resistor R2, and the other end of the capacitor C1 is grounded. The connection point of the capacitor C1, the resistor R1 and the resistor R2 is the output end of the sampling circuit.
The contactor power saver detecting circuit according to claim 3, wherein the sampling circuit further comprises a Zener diode Z1, and the Zener diode Z1 is connected in parallel across C1, wherein the cathode of the Zener diode Z1 and the resistor R1 and the resistor R2 are provided. Connected to the connection point of capacitor C1, the anode of Zener diode Z1 is grounded.
The contactor power saver detecting circuit according to claim 1, wherein the sampling circuit comprises a sampling circuit formed by two ends of the inductor L1, the resistor R3 and the resistor R4, and the inductor L1, the resistor R3 and the resistor R4 are connected in series. At the input end, the connection point of the resistor R3 and the resistor R4 is the output end of the sampling circuit.
The contactor power saver detecting circuit according to claim 5, wherein the sampling circuit further comprises a Zener diode Z1, and the Zener diode Z1 is connected in parallel across the resistor R4, wherein the cathode of the Zener diode Z1 and the resistor R3 and the resistor The connection point of R4 is connected, and the anode of Zener diode Z1 is grounded.
A contactor power saver detecting circuit includes a first rectifier bridge and a main power circuit for controlling current of the contactor coil; and further comprising: a first diode, a second diode, a sampling circuit and a threshold Comparing circuit; the input ends of the first rectifier bridge are respectively connected to the anodes of the first diode and the second diode, the positive output end of the first rectifier bridge is connected to the main power circuit, and the negative output end of the first rectifier bridge is grounded, The first diode and the cathode of the second diode are connected and grounded through the input end of the sampling circuit, the output end of the sampling circuit is connected to the input end of the threshold comparison circuit, and the output end of the threshold comparison circuit is connected to the main power circuit; The threshold comparison circuit internally has a reference one and a reference two. When the peak voltage of the output signal of the sampling circuit is greater than the reference one, the threshold comparison circuit outputs a control signal to control the operation of the main power circuit, and the contactor pulls in; when the output signal of the sampling circuit has a valley value When the voltage is less than the reference two, the threshold comparison circuit outputs a control signal to control the main power circuit to be turned off, and the contactor is released; when the input voltage is an alternating current sampling circuit Equal to the output of the signal voltage output signal peak voltage and the input voltage sampling circuit is DC.
The contactor power saver detecting circuit according to claim 7, further comprising a Zener diode, wherein the cathode of the Zener diode is connected to the output end of the sampling circuit, and the anode of the Zener diode is grounded.
The contactor power saver detecting circuit according to claim 7, wherein the sampling circuit comprises a resistor R1, a resistor R2 and a capacitor C1, a resistor R1 and a resistor R2 connected in series, and one end of the resistor R1 and the resistor R2 connected in series is connected to the first The cathode connection point of the diode and the second diode, the other end of the resistor R1 and the resistor R2 connected in series is grounded, one end of the capacitor C1 is connected with the connection point of the resistor R1 and the resistor R2, the other end of the capacitor C1 is grounded, the capacitor C1, the resistor The connection point of R1 and resistor R2 is the output of the sampling circuit.
The contactor power saver detecting circuit according to claim 9, wherein the sampling circuit further comprises a Zener diode Z1, and the Zener diode Z1 is connected in parallel across C1, wherein the cathode of the Zener diode Z1 and the resistor R1 and the resistor R2 are connected. Connected to the connection point of capacitor C1, the anode of Zener diode Z1 is grounded.
The contactor power saver detecting circuit according to claim 7, wherein the sampling circuit comprises an inductor L1, a resistor R3 and a resistor R4, and a cathode connection point of the first diode and the second diode is sequentially passed through the inductor L1. The resistor R3 and the resistor R4 are grounded, and the connection point of the resistor R3 and the resistor R4 is the output end of the sampling circuit.
The contactor power saver detecting circuit according to claim 11, wherein the sampling circuit further comprises a Zener diode Z1, and the Zener diode Z1 is connected in parallel across the resistor R4, wherein the cathode of the Zener diode Z1 and the resistor R3 and the resistor The connection point of R4 is connected, and the anode of Zener diode Z1 is grounded.