CN109585223B - Contactor control circuit - Google Patents

Contactor control circuit Download PDF

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CN109585223B
CN109585223B CN201811478213.XA CN201811478213A CN109585223B CN 109585223 B CN109585223 B CN 109585223B CN 201811478213 A CN201811478213 A CN 201811478213A CN 109585223 B CN109585223 B CN 109585223B
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switch
voltage
output
resistor
capacitor
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CN109585223A (en
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苏俊熙
符威
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Shenzhen Nanyun Microelectronics Co ltd
Mornsun Guangzhou Science and Technology Ltd
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Shenzhen Nanyun Microelectronics Co ltd
Mornsun Guangzhou Science and Technology Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H47/00—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current
    • H01H47/22—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current for supplying energising current for relay coil
    • H01H47/32—Energising current supplied by semiconductor device
    • H01H47/325—Energising current supplied by semiconductor device by switching regulator
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H47/00—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current
    • H01H47/02—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current for modifying the operation of the relay

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  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)
  • Inverter Devices (AREA)

Abstract

The invention discloses a contactor control circuit, which comprises a voltage detection circuit and a duty ratio control circuit; the voltage detection circuit firstly reduces the bus voltage to a proper range through the divider resistor, then filters an alternating current component through the low-pass filter, the remaining direct current component is used as the output of the voltage detection circuit, and the output voltage is recorded as VS(ii) a The duty ratio control circuit detects the output voltage VSOutput duty ratio D, VSX D is denoted as KD，KDIs a constant set inside the duty ratio control circuit. Setting K of the inventionDThe constant value is constant, the current of the coil of the contactor can be kept constant in a wide input range, so that the PF value of the power saver of the contactor can be improved, a bus capacitor and a sampling resistor can be removed, and the average value of the current of the coil of the contactor is kept constant in a wide-voltage AC/DC input voltage range.

Description

Contactor control circuit
Technical Field
The invention relates to the field of alternating current contactors, in particular to a contactor power saver with a power factor correction function.
Background
The traditional contactor operating system consists of a coil, a static iron core, an armature and a reaction spring. When the coil of the contactor is electrified, an attraction force is generated between the static iron core and the armature, when the attraction force is larger than the counterforce of the spring, the armature is attracted to the static iron core until the armature is contacted with the static iron core, the main contact is closed, and the process is called as an attraction process. The process that the coil is continuously electrified, the armature keeps contact with the static iron core, and the main contact keeps a closed state is called a holding process. When the current in the coil is reduced or interrupted, the attraction force of the static iron core to the armature is reduced, and when the attraction force is smaller than the reaction force of the spring, the armature returns to the open position, and the main contacts are separated, and the process is called a releasing process. From an electrical point of view, the contactor coil can be equivalent to an inductor with a certain internal resistance.
The contactor is used for frequently connecting and disconnecting an alternating current circuit and a direct current circuit, and can remotely control a low-voltage apparatus. The main control object is an electric motor, and the electric motor can also be used for controlling electric loads such as an electric heater, an electric welding machine, an illuminating lamp and the like. At present, the using amount of the national contactors is large, when the contactors with medium and large capacity are in a holding state, the active power consumed by each contactor is about 60W on average, and the power factor is only about 0.3. The reduction of the energy consumption of the contactor makes a great contribution to energy conservation and emission reduction.
The existing contactor electricity-saving device adopts the mode of converting alternating current into direct current, attracting large current and keeping small current, thereby greatly reducing the iron loss and copper loss of an electromagnetic coil and the loss of a short-circuit ring and reducing the active power consumption by more than 90 percent. The chip controls the conduction duty ratio of the MOS tube to realize the control of large current suction and small current suction. However, these techniques have certain defects, only solve the problem of active power consumption, but do not contribute to the improvement of the power factor, and some power saving techniques can also reduce the power factor. As in the 200510029373.2 patent, the solenoid coil is energized in a pulsed fashion, causing the solenoid coil to operate at a constant low current; by adopting the mode to work, a large amount of harmonic waves can be generated, the effective value of the input current does not follow the input voltage, the power factor is very low, and the actual PF value is smaller than 0.3 when a prototype is manufactured according to the technology. The techniques of the '201210196762.4 and' 201010040019.9 patents, in which the solenoids are energized near the zero crossing of the input ac voltage so that the input current and output voltage are in a similar anti-phase state, were prototyped, and had a power factor of less than 0.1.
In order to promote the contactor with the power saver, manufacturers want to change the use mode and appearance of the contactor with the power saver little compared with the traditional contactor. The power saver must be placed inside the contactor housing, which is a very high requirement on the size of the power saver. According to the above-mentioned published patent, the main power device of the contactor power saver includes a rectifier bridge, a bus capacitor, a MOS transistor, a freewheeling diode, and a current sampling resistor. The above devices are not all necessary, and the power devices can be further reduced by improving the control mode, and the original performance is unchanged or improved. Further increasing the market competitiveness of the power saver.
Because the conventional contactor has no control circuit, and the coil current can change along with the input voltage, the input voltage range of the conventional contactor is narrow, and the common input range is 80% Um-110% Um. At present, manufacturers have provided new requirements for the power saver of the contactor, and provide wide-voltage alternating current and direct current universal contactors. For example, the requirements of four wide-voltage alternating current and direct current universal contactors of 24V-48V, 48V-120V, 100V-250V and 250V-500V are provided.
Disclosure of Invention
The technical problem solved by the invention is that aiming at the defects existing in the prior art and new market requirements, by improving the control method, the PF value of the contactor electricity-saving device is improved, meanwhile, the bus capacitor and the sampling resistor in the contactor electricity-saving device can be removed, and the average value of the current of the contactor coil is constant in a wide-voltage AC/DC input voltage range.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a contactor control circuit, comprising: the device comprises a voltage detection circuit and a duty ratio control circuit; the voltage detection circuit firstly reduces the bus voltage to a proper range through a divider resistor, and the voltage division ratio is recorded as KVThen, the AC component is filtered out by a low-pass filter, the remaining DC component is used as the output of a voltage detection circuit, and the output voltage is recorded as VS(ii) a The duty ratio control circuit detects the output voltage VSOutput duty ratio D, VSX D is denoted as KD，KDIs a constant set inside the duty ratio control circuit.
As a specific embodiment of the voltage detection circuit, the voltage detection circuit includes: the device comprises a resistor R1, a resistor R2 and a capacitor C1, wherein the resistor R1 and the resistor R2 are connected in series and then are used for being connected with two ends of rectified bus voltage in parallel, one end of the capacitor C1 is connected with a connection point of the resistor R1 and the resistor R2 and serves as an output end of a voltage detection circuit to output the output voltage VSAnd the other end of the capacitor C1 is grounded.
A first specific embodiment of the duty control circuit includes: operational amplifier U1, MOS tube Q2 and resistor RD1Switch K1, switch K2, switch K3 and capacitor CD1Capacitor CD2Phase inverter U2, comparator U3, RS trigger U4, clock generator, pull-in holding switching circuit and constant current sourceM1 and a constant current source M2; the pull-in holding switching circuit is used for controlling the switch K1 to be switched on and the switch K2 to be switched off in the pull-in stage and controlling the switch K2 to be switched on and the switch K1 to be switched off in the holding stage; the positive input end of the operational amplifier U1 is used for inputting the output voltage VSNegative input terminal of operational amplifier U1 and resistor RD1One end of the operational amplifier U1 is connected with the drain electrode of the MOS transistor Q2, and the output end of the operational amplifier U1 is connected with the grid electrode of the MOS transistor Q2; resistance RD1The other end of the first and second electrodes is grounded; the input end of the constant current source M1 is used for inputting a supply voltage VDDThe output end of the constant current source M1 is connected with the drain electrode of the MOS tube Q2; the input end of the constant current source M2 is used for inputting a supply voltage VDDFirst switch ends of the switch K1, the switch K2 and the switch K3 are connected with the output end of the constant current source M2 and the positive input end of the comparator U3, and a second switch end of the switch K1 is connected with the positive input end of the comparator U3 through a capacitor CD1The second switch end of the switch K2 passes through a capacitor C and is groundedD2The second switch end of the switch K3 is grounded; the control end of the switch K1 is connected with the first output end of the suction holding switching circuit, and the control end of the switch K2 is connected with the second output end of the suction holding switching circuit; the control end of the switch K3 is connected with the output of the inverter U2; the negative input end of the comparator U3 inputs a comparison threshold voltage VTHThe output end of the comparator U3 is connected with the R input end of the RS trigger U4, the S input end of the RS trigger U4 is connected with the clock generator, the output end of the RS trigger U4 is connected with the inverter U2 and is also the output end of the duty ratio control circuit, and a signal for controlling the on and off of a main power switch tube in the contactor is output.
A second specific embodiment of the duty control circuit includes: operational amplifier U1, MOS tube Q2 and resistor RD1Resistance RD2Switch K1, switch K2, switch K3 and capacitor CD1The circuit comprises a phase inverter U2, a comparator U3, an RS trigger U4, a clock generator, a pull-in holding switching circuit, a constant current source M1 and a constant current source M2; the pull-in holding switching circuit is used for controlling the switch K1 to be switched on and the switch K2 to be switched off in the pull-in stage and controlling the switch K2 to be switched on and the switch K1 to be switched off in the holding stage; the positive input end of the operational amplifier U1 is used for inputting the output voltage VSThe negative input end of the operational amplifier U1 is respectively connected with the first switch ends of the switch K1 and the switch K2 and the drain electrode of the MOS transistor Q2The output end of the operational amplifier U1 is connected with the grid of the MOS transistor Q2; the second switch terminal of the switch K1 passes through a resistor RD1To ground, the second switch terminal of the switch K2 passes through a resistor RD2The control end of the switch K1 is connected with the first output end of the attracting and holding switching circuit, and the control end of the switch K2 is connected with the second output end of the attracting and holding switching circuit; the input end of the constant current source M1 is used for inputting a supply voltage VDDThe output end of the constant current source M1 is connected with the drain electrode of the MOS tube Q2; the input end of the constant current source M2 is used for inputting a supply voltage VDDThe output end of the constant current source M2, the positive input end of the comparator U3, the first switch end of the switch K3 and the capacitor CD1Is connected to one terminal of a capacitor CD1The other end of the switch K3 is grounded, the second switch end of the switch K3 is grounded, and the control end of the switch K3 is connected with the output of the phase inverter U2; the negative input end of the comparator U3 inputs a comparison threshold voltage VTHThe output end of the comparator U3 is connected with the R input end of the RS trigger U4, the S input end of the RS trigger U4 is connected with the clock generator, the output end of the RS trigger U4 is connected with the inverter U2 and is also the output end of the duty ratio control circuit, and a signal for controlling the on and off of a main power switch tube in the contactor is output.
Through the description on the basic principle of the scheme, the scheme of the patent can obtain the following beneficial effects:
1. the duty ratio does not change along with the fluctuation of the bus voltage, and the bus capacitor can be removed;
2. the input current can change along with the input voltage, and the PF value is high;
3. the current of the coil is indirectly controlled to be constant by sampling the input voltage, and the current sampling resistor can be removed;
4. the average value of the coil current is constant under the wide input voltage, and the input alternating current and direct current are universal.
Drawings
Fig. 1 is a main power circuit and an equivalent circuit of a contactor power saver;
FIG. 2 is a schematic circuit diagram of the first embodiment;
FIG. 3 illustrates a first embodiment key node waveform;
fig. 4 is a schematic circuit diagram of a second embodiment.
Detailed Description
The inventive concept of the present application generates ideas as follows:
the main power circuit of the existing contactor power saver is shown in the left diagram of fig. 1, and mainly comprises a contactor coil L1, a diode D1 and a MOS transistor Q1. The peak value of the bus voltage is UMThe duty cycle of the driving signal is D. If the duty cycle is constant, then the left diagram of fig. 1 can be equivalent to the right diagram, where the peak value of the bus voltage is U, if only the current parameter of the contactor coil L1 is concernedM*D。
If the bus capacitor is removed, the rectified voltage is a steamed bread wave. The components above 100Hz are very small after the steamed bread wave is subjected to Fourier decomposition, so that the formula of the steamed bread wave can be approximated as follows:
UIN(t)＝UM·|sinω0t|≈UM·(0.6365+0.424·cos2ω0t)
wherein, UMIs the peak value of the input voltage, omega0Is the angular frequency corresponding to 50Hz power frequency.
Let the internal resistance of the contactor coil L1 be RCOILInductance of the coil is LCOIL. Using this bus voltage UIN(t) the contactor coil L1 is excited, and then the dc component and the ac component of the contactor coil L1 are obtained.
For 0HZ (direct current component), the impedance of the coil is RCOIL(ii) a For 100Hz, the impedance of the coil is:
Figure GDA0002206904310000041
coil direct current component:
Figure GDA0002206904310000042
coil alternating current component:
Figure GDA0002206904310000043
similarly, it is also easy to obtain the input of DC voltage UDCWhen, the current of the coil is:
when the input is direct current, coil current:
Figure GDA0002206904310000044
the voltage detection circuit is a voltage division filter circuit, and the input of the voltage detection circuit is connected with the rectified bus voltage. The voltage detection circuit firstly reduces the bus voltage to a proper range through a divider resistor, and the voltage division ratio is recorded as KVThen, the AC component is filtered out by a low-pass filter, the remaining DC component is used as the output of a voltage detection circuit, and the output voltage is recorded as VS. The formula of the steamed bread wave is analyzed, so that the formula is easily obtained, and the output voltage of the voltage detection circuit is as follows:
when the input is alternating current, the detection circuit outputs voltage:
VS_AC＝0.6365·KV·UM(4)
when the input is direct current, the detection circuit outputs voltage:
VS_DC＝KV·UDC(5)
the duty ratio control circuit of the invention detects the output voltage V of the voltage detection circuitSAnd outputting the duty ratio D. Wherein VSThe relationship to D is:
VS·D＝KD(6)
wherein KDThe current of the contactor coil L1 can be made constant over a wide input range by a constant determined internally to the duty cycle control circuit. Substituting the formula (4) and the formula (6) into the formula (1) and the formula (2) can obtain an alternating current component and a direct current component of the coil when the input is alternating current. The coil current of the coil when the input is dc can be obtained by substituting the formula (5) and the formula (6) into the formula (3).
When the input is alternating current, the direct current component of the coil:
Figure GDA0002206904310000051
when the input is alternating current, the coil alternating current component:
when the input is direct current, coil current:
Figure GDA0002206904310000053
from the above current equations, it can be seen that the current of the coil is independent of the input voltage through the control scheme of the present invention, which indicates that the coil current is constant over a wide range of input voltages. The average current of the coil is the same for both the ac input and the dc input.
Because the output of the voltage detection circuit is approximate to a direct-current voltage signal, the output duty ratio of the duty ratio control circuit is unchanged in the whole power frequency period. This control is somewhat similar to the control principle of a PFC. According to the formula Δ I ═ VIN·TON/LCOILKnown as TONWithout following the fluctuations in the bus voltage, the input current follows the input voltage, and the PF value of this control method is relatively high.
The detailed description of the embodiments of the invention is provided for a better understanding of the improvements made over the prior art.
First embodiment
Fig. 2 is a schematic diagram of a contactor control circuit according to a first embodiment of the present invention, which includes a voltage detection circuit and a duty cycle control circuit.
The voltage detection circuit comprises a resistor R1, a resistor R2 and a capacitor C1. The resistor R1 and the resistor R2 are connected in series and then connected in parallel to two ends of the rectified bus voltage. One end of the capacitor C1 is connected with the connection point of the resistor R1 and the resistor R2 and is used as the output end of the voltage detection circuit, and the other end of the capacitor C1 is grounded. The voltage detection circuit functions to divide and filter the voltage, reduce the bus voltage to an appropriate value and extract its dc component.
The duty ratio control circuit of the first embodiment comprises an operational amplifier U1, a MOS transistor Q2 and a resistor RD1Switch K1, switch K2, switch K3 and capacitor CD1Capacitor CD2The circuit comprises an inverter U2, a comparator U3, an RS trigger U4, a clock generator, a pull-in holding switching circuit, a constant current source M1 and a constant current source M2. The positive input end of the operational amplifier U1 is connected with the output of the voltage detection circuit, and the negative input end of the operational amplifier U1 is connected with the resistor RD1One end of the operational amplifier U1 is connected with the drain electrode of the MOS transistor Q2, and the output end of the operational amplifier U1 is connected with the grid electrode of the MOS transistor Q2. Resistance RD1And the other end of the same is grounded. Input end of constant current source M1 and voltage VDDAnd the output end of the constant current source M1 is connected with the drain electrode of the MOS tube Q2. Input end of constant current source M2 and voltage VDDThe first switch ends of the switch K1, the switch K2 and the switch K3 are connected with the output end of the constant current source M2 and the positive input end of the comparator U3, and the second switch end of the switch K1 is connected with the positive input end of the comparator U3 through a capacitor CD1The second switch end of the switch K2 passes through a capacitor C and is groundedD2The second switch terminal of the switch K3 is grounded. The control end of the switch K1 is connected with the first output end of the suction holding switching circuit, and the control end of the switch K2 is connected with the second output end of the suction holding switching circuit. The control terminal of switch K3 is connected to the output of inverter U2. Negative input terminal of comparator U3 and voltage VTHAnd the output end of the comparator U3 is connected with the R input end of the RS flip-flop U4, the S input end of the RS flip-flop U4 is connected with the clock generator, and the output end of the RS flip-flop U4 is also the output end of the duty ratio control circuit while being connected with the inverter U2, and outputs a GATE signal.
Voltage VDD: the voltage value is stable and unchanged for the supply voltage.
Voltage VTH: for comparing the threshold voltages, the voltage values are stable.
VCDVoltage: in the pull-in stage, the switch K1 is turned on, the switch K2 is turned off, and the switch V is turned onCDThe voltage being a capacitance CD1A voltage across; during the holding phase, the switch K2 is on, K1 is off, and VCDThe voltage being a capacitance CD2The voltage of (c). VCDVoltage ofThe waveform is a sawtooth wave, and the slope of the sawtooth wave mainly follows the capacitor CD1Capacitance value, capacitance CD2Capacitance, input voltage variation.
The GATE signal: and controlling the on and off signals of a main power switch tube Q1 in the contactor.
The pull-in holding switching circuit is used for controlling the switch K1 to be switched on and switched off the switch K2 in the pull-in stage and controlling the switch K2 to be switched on and switched off the switch K1 in the holding stage. After the control circuit is powered on and enabled, the control circuit enters a pull-in stage, enters a pull-in stage after a fixed time delay, maintains the stage all the time, and does not enter the pull-in stage until the next power-off restart. This function is easily implemented with semiconductor logic circuits. Other embodiments are the same.
The operation principle of the present embodiment is explained below with reference to fig. 3. According to the principle of negative feedback of the operational amplifier U1 and virtual end and virtual break of the input end, the voltage of the negative input end of the operational amplifier U1 is equal to the output voltage V of the voltage detection circuitS. The current of the constant current source M1 is equal to:
ID1＝VS/RD1
the constant current source M1 and the constant current source M2 form a mirror current source with the mirror current proportion of KIThen the output current of the constant current source M2 is:
ID2＝ID1/KI。
capacitor CD1Determining the duty ratio of the pull-in stage, and the capacitance CD2Determining the duty cycle of the holding phase, capacitor CD1And a capacitor CD2The capacity value multiple of (2) is the multiple of the pull-in holding current. As shown in FIG. 3, in the pull-in phase, the switch K1 is turned on, the switch K2 is turned off, and V is turned onCDThe voltage being a capacitance CD1A voltage across; in the holding phase, the switch K1 is not conducted, the switch K2 is conducted, VCDThe voltage being a capacitance CD2The voltage of (c). Current ID2Capacitor CD1Or a capacitor CD2The capacitor voltage rises linearly when it rises to VTHWhen the voltage is high, the comparator U3 outputs high level, the RS trigger U4 outputs low level, and the K3 closes the capacitor CD1Or a capacitor CD2Voltage ofReset to 0. And when the clock generator sends a high level signal in the next period, the RS trigger U4 is controlled to output a high level. The on-time of the duty cycle GATE is:
a suction stage:
a holding stage:
Figure GDA0002206904310000072
when the bus voltage becomes high, the capacitor C is suppliedD1Or a capacitor CD2Charging current I ofD2The voltage on the capacitor reaches the voltage value V more quickly when the voltage becomes largerTHThe duty cycle will be reduced; conversely, when the bus voltage becomes low, the duty ratio becomes large. So that the bus voltage has an inverse relationship with the output duty cycle. In the present embodiment, by providing the capacitor CD1And a capacitor CD2And setting the duty ratio of the suction stage and the holding stage according to the size of the liquid.
Second embodiment
A circuit schematic of the second embodiment is shown in fig. 4. The basic principle of the second embodiment is the same as that of the first embodiment. Except that the second embodiment is through a resistor RD1And a resistance RD2To control the charging current ID2The duty ratio of the suction phase and the suction phase is set. The voltage detection circuit of the second embodiment is the same as that of the first embodiment. The duty ratio control circuit of the second embodiment is connected as follows.
The duty ratio control circuit of the second embodiment comprises an operational amplifier U1, a MOS transistor Q2 and a resistor RD1Resistance RD2Switch K1, switch K2, switch K3 and capacitor CD1The circuit comprises an inverter U2, a comparator U3, an RS trigger U4, a clock generator, a pull-in holding switching circuit, a constant current source M1 and a constant current source M2. The positive input end of the operational amplifier U1 is connected with the output of the voltage detection circuit, the negative input end of the operational amplifier U1 is connected with the switch K1, the first switch end of the switch K2 and the drain electrode of the MOS tube Q2, and the output end of the operational amplifier U1 is connected with the grid electrode of the MOS tube Q2. The second switch terminal of the switch K1 passes through a resistor RD1To ground, the second switch terminal of the switch K2 passes through a resistor RD2The control end of the switch K1 is connected with the first output end of the attracting and holding switching circuit, and the control end of the switch K2 is connected with the second output end of the attracting and holding switching circuit. Input end of constant current source M1 and voltage VDDAnd the output end of the constant current source M1 is connected with the drain electrode of the MOS tube Q2. Input end of constant current source M2 and voltage VDDThe output end of the constant current source M2 is connected with the positive input end of the comparator U3, the first switch end of the switch K3 and the capacitor CD1Is connected to one terminal of a capacitor CD1The second switch terminal of the switch K3 is grounded, and the control terminal of the switch K3 is connected to the output of the inverter U2. Negative input terminal of comparator U3 and voltage VTHAnd the output end of the comparator U3 is connected with the R input end of the RS flip-flop U4, the S input end of the RS flip-flop U4 is connected with the clock generator, and the output end of the RS flip-flop U4 is also the output end of the duty ratio control circuit while being connected with the inverter U2, and outputs a GATE signal.
Voltage VTH: for comparing the threshold voltages, the voltage values are stable.
VCDVoltage: vCDThe voltage being a capacitance CD1The voltage of (c). VCDThe voltage waveform is a sawtooth wave, and the slope of the sawtooth wave mainly follows the resistor RD1Resistance value, resistance RD2Resistance, input voltage variation.
The key node waveforms of the second embodiment are the same as those of the first embodiment and can be explained by referring to fig. 3. VCDThe voltage being a capacitance CD1The voltage of (c). In the pull-in stage, the switch K1 is turned on, the switch K2 is not turned on, and the current flows from RD1Flowing through; in the holding phase, the switch K1 is not conducted, the switch K2 is conducted, and the current flows from RD2And flows through. Resistance RD1Is a value ratio RD2To be large, flows through the resistance RD1Current specific resistance RD2Is small. In the pull-in phase, the capacitor C is suppliedD1Small charging current, capacitor CD1The voltage rises slowly and the duty ratio is large; feeding capacitor C during the holding phaseD1The charging current of (2) is large and the duty ratio is small. When the bus voltage becomes high, the capacitor C is suppliedD1The charged current becomes large and the capacitance becomes largeThe voltage on reaches the voltage value V more quicklyTHThe duty cycle will be reduced; conversely, when the bus voltage becomes low, the duty ratio becomes large. So that the bus voltage has an inverse relationship with the output duty cycle. In the present embodiment, by setting the resistance RD1And RD2The resistance value of (1) is respectively set at the duty ratio of the suction stage and the suction stage.
The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.

Claims (4)

1. A contactor control circuit, comprising: the device comprises a voltage detection circuit and a duty ratio control circuit; the voltage detection circuit firstly reduces the bus voltage to a proper range through a divider resistor, and the voltage division ratio is recorded as KVThen, the AC component is filtered out by a low-pass filter, the remaining DC component is used as the output of a voltage detection circuit, and the output voltage is recorded as VS(ii) a The duty ratio control circuit detects the output voltage VSOutput duty ratio D, VSX D is denoted as KD，KDA constant set for the duty ratio control circuit;
the duty ratio control circuit includes: operational amplifier U1, MOS tube Q2 and resistor RD1Switch K1, switch K2, switch K3 and capacitor CD1Capacitor CD2The circuit comprises a phase inverter U2, a comparator U3, an RS trigger U4, a clock generator, a pull-in holding switching circuit, a constant current source M1 and a constant current source M2; the pull-in holding switching circuit is used for controlling the switch K1 to be switched on and the switch K2 to be switched off in the pull-in stage and controlling the switch K2 to be switched on and the switch K1 to be switched off in the holding stage; the positive input end of the operational amplifier U1 is used for inputting the output voltage VSNegative input terminal of operational amplifier U1 and resistor RD1One end of the operational amplifier U1 is connected with the drain electrode of the MOS transistor Q2, and the output end of the operational amplifier U1 is connected with the grid electrode of the MOS transistor Q2; resistance RD1To another one ofThe end is grounded; the input end of the constant current source M1 is used for inputting a supply voltage VDDThe output end of the constant current source M1 is connected with the drain electrode of the MOS tube Q2; the input end of the constant current source M2 is used for inputting a supply voltage VDDFirst switch ends of the switch K1, the switch K2 and the switch K3 are connected with the output end of the constant current source M2 and the positive input end of the comparator U3, and a second switch end of the switch K1 is connected with the positive input end of the comparator U3 through a capacitor CD1The second switch end of the switch K2 passes through a capacitor C and is groundedD2The second switch end of the switch K3 is grounded; the control end of the switch K1 is connected with the first output end of the suction holding switching circuit, and the control end of the switch K2 is connected with the second output end of the suction holding switching circuit; the control end of the switch K3 is connected with the output of the inverter U2; the negative input end of the comparator U3 inputs a comparison threshold voltage VTHThe output end of the comparator U3 is connected with the R input end of the RS trigger U4, the S input end of the RS trigger U4 is connected with the clock generator, the output end of the RS trigger U4 is connected with the inverter U2 and is also the output end of the duty ratio control circuit, and a signal for controlling the on and off of a main power switch tube in the contactor is output.
2. The contactor control circuit as claimed in claim 1, wherein the voltage detection circuit comprises: the device comprises a resistor R1, a resistor R2 and a capacitor C1, wherein the resistor R1 and the resistor R2 are connected in series and then are used for being connected with two ends of rectified bus voltage in parallel, one end of the capacitor C1 is connected with a connection point of the resistor R1 and the resistor R2 and serves as an output end of a voltage detection circuit to output the output voltage VSAnd the other end of the capacitor C1 is grounded.
3. A contactor control circuit, comprising: the device comprises a voltage detection circuit and a duty ratio control circuit; the voltage detection circuit firstly reduces the bus voltage to a proper range through a divider resistor, and the voltage division ratio is recorded as KVThen, the AC component is filtered out by a low-pass filter, the remaining DC component is used as the output of a voltage detection circuit, and the output voltage is recorded as VS(ii) a The duty ratio control circuit detects the output voltage VSOutput duty ratio D, VSX D is denoted as KD，KDTo account forA constant set inside the duty ratio control circuit;
the duty ratio control circuit includes: operational amplifier U1, MOS tube Q2 and resistor RD1Resistance RD2Switch K1, switch K2, switch K3 and capacitor CD1The circuit comprises a phase inverter U2, a comparator U3, an RS trigger U4, a clock generator, a pull-in holding switching circuit, a constant current source M1 and a constant current source M2; the pull-in holding switching circuit is used for controlling the switch K1 to be switched on and the switch K2 to be switched off in the pull-in stage and controlling the switch K2 to be switched on and the switch K1 to be switched off in the holding stage; the positive input end of the operational amplifier U1 is used for inputting the output voltage VSThe negative input end of the operational amplifier U1 is respectively connected with the first switch ends of the switch K1 and the switch K2 and the drain electrode of the MOS tube Q2, and the output end of the operational amplifier U1 is connected with the gate electrode of the MOS tube Q2; the second switch terminal of the switch K1 passes through a resistor RD1To ground, the second switch terminal of the switch K2 passes through a resistor RD2The control end of the switch K1 is connected with the first output end of the attracting and holding switching circuit, and the control end of the switch K2 is connected with the second output end of the attracting and holding switching circuit; the input end of the constant current source M1 is used for inputting a supply voltage VDDThe output end of the constant current source M1 is connected with the drain electrode of the MOS tube Q2; the input end of the constant current source M2 is used for inputting a supply voltage VDDThe output end of the constant current source M2, the positive input end of the comparator U3, the first switch end of the switch K3 and the capacitor CD1Is connected to one terminal of a capacitor CD1The other end of the switch K3 is grounded, the second switch end of the switch K3 is grounded, and the control end of the switch K3 is connected with the output of the phase inverter U2; the negative input end of the comparator U3 inputs a comparison threshold voltage VTHThe output end of the comparator U3 is connected with the R input end of the RS trigger U4, the S input end of the RS trigger U4 is connected with the clock generator, the output end of the RS trigger U4 is connected with the inverter U2 and is also the output end of the duty ratio control circuit, and a signal for controlling the on and off of a main power switch tube in the contactor is output.
4. The contactor control circuit as claimed in claim 3, wherein the voltage detection circuit comprises: the circuit comprises a resistor R1, a resistor R2 and a capacitor C1, wherein the resistor R1 and the resistor R2 are connected in series and then are used for being connected in parallel with two ends of rectified bus voltage, and one of the capacitors C1The end of the output voltage V is connected with the connection point of the resistor R1 and the resistor R2 and serves as the output end of the voltage detection circuit to output the output voltage VSAnd the other end of the capacitor C1 is grounded.
CN201811478213.XA 2018-12-05 2018-12-05 Contactor control circuit Active CN109585223B (en)

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PCT/CN2019/119576 WO2020114247A1 (en) 2018-12-05 2019-11-20 Control circuit for contactor

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Publication number Priority date Publication date Assignee Title
CN109585223B (en) * 2018-12-05 2020-02-14 深圳南云微电子有限公司 Contactor control circuit
CN110112037B (en) * 2019-04-18 2021-06-11 深圳南云微电子有限公司 Contactor power-saving circuit

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CN106208668A (en) * 2016-09-07 2016-12-07 广州金升阳科技有限公司 Pfc circuit, PFC control circuit and Switching Power Supply
CN107834839A (en) * 2017-10-19 2018-03-23 深圳南云微电子有限公司 A kind of contactor electricity-saving appliance

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CN109585223B (en) * 2018-12-05 2020-02-14 深圳南云微电子有限公司 Contactor control circuit

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Publication number Priority date Publication date Assignee Title
CN201229512Y (en) * 2008-07-16 2009-04-29 葛勇 Voltage regulator
EP2546989A1 (en) * 2010-03-09 2013-01-16 Yazaki Corporation Control device of electromagnetic inductive load
CN106208668A (en) * 2016-09-07 2016-12-07 广州金升阳科技有限公司 Pfc circuit, PFC control circuit and Switching Power Supply
CN107834839A (en) * 2017-10-19 2018-03-23 深圳南云微电子有限公司 A kind of contactor electricity-saving appliance

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