CN110223881B - Contactor control circuit and contactor coil voltage control method - Google Patents
Contactor control circuit and contactor coil voltage control method Download PDFInfo
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- CN110223881B CN110223881B CN201910303991.3A CN201910303991A CN110223881B CN 110223881 B CN110223881 B CN 110223881B CN 201910303991 A CN201910303991 A CN 201910303991A CN 110223881 B CN110223881 B CN 110223881B
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- 239000003990 capacitor Substances 0.000 claims description 133
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- 230000001629 suppression Effects 0.000 claims description 10
- 230000001052 transient effect Effects 0.000 claims description 10
- 238000010586 diagram Methods 0.000 description 10
- 230000001105 regulatory effect Effects 0.000 description 6
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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
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Abstract
The invention relates to a contactor control circuit and a contactor coil voltage control method, wherein a voltage acquisition circuit of the contactor control circuit is connected with a power supply circuit and is used for acquiring the current power supply voltage of the power supply circuit, an input end of the control circuit is connected with an output end of the voltage acquisition circuit, the control circuit adjusts a duty ratio according to the current power supply voltage to output a control signal, an input end of a driving circuit is connected with an output end of the control circuit, an output end of the driving circuit is connected with a switching element, the driving circuit receives the control signal sent by the control circuit and controls the switching element to be turned on and off, the switching element is connected with a coil, and the switching element is used for controlling the existence of voltage at two ends of the coil. The contactor coil voltage control method adjusts the duty ratio according to the current power supply voltage and the current temperature of the coil to output a control signal to control the voltage at two ends of the control coil.
Description
Technical Field
The invention relates to the field of piezoelectric devices, in particular to a contactor control circuit and a coil voltage control method.
Background
The traditional contactor is powered on through a coil, and then the lower iron core generates magnetic force to enable the upper iron core to overcome the elastic force of the reset spring to operate, and the upper iron core drives the moving contact to move to contact with the fixed contact. The alternating current contactor is a low-voltage electrical appliance which is frequently operated, and has wide application range. The control coil has multiple voltage specifications, and has both alternating current control and direct current control,
At present, different coils are required to be configured for the stock of the same shell frame product, the coils are required to be matched with corresponding voltages during use, the field use is complex, and the coil maintenance power consumption is high. With the development of automation technology, some methods for controlling the coil of the alternating current contactor appear, but most of the methods are formed by modifying a power chip, the working voltage range of the coil is not wide enough, and the circuit design is complex.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide the contactor control circuit and the contactor coil voltage control method which are safe and stable in performance, simple and compact in structure and low in cost.
In order to achieve the above purpose, the invention adopts the following technical scheme:
A contactor control circuit comprises a power supply circuit, a voltage acquisition circuit, a control circuit, a driving circuit, a switching element and a coil;
The input end of the power supply circuit is connected with an external power supply for taking electricity, and the output end of the power supply circuit is connected with the voltage acquisition circuit, the control circuit, the switching element and the coil to supply power for the voltage acquisition circuit, the control circuit, the switching element and the coil;
The input end of the voltage acquisition circuit is connected with the power supply circuit and used for acquiring the current power supply voltage of the power supply circuit, the input end of the control circuit is connected with the output end of the voltage acquisition circuit,
The control circuit adjusts the duty ratio according to the current power supply voltage to output a control signal, the input end of the driving circuit is connected with the output end of the control circuit, the output end of the driving circuit is connected with the switching element, and the driving circuit receives the control signal sent by the control circuit and controls the switching element to be turned on and off;
the switching element is connected with the coil, and the on-off of the switching element controls the existence of the voltage at two ends of the coil.
Preferably, the temperature control circuit further comprises a temperature acquisition circuit, wherein the input end of the temperature acquisition circuit is connected with the coil and used for acquiring the temperature of the coil, the output end of the temperature acquisition circuit is connected with the control circuit and used for sending an acquired temperature signal of the coil to the control circuit, and the control circuit further adjusts the duty ratio according to the current power supply voltage and the current temperature of the coil so as to output a control signal.
The power supply circuit comprises a power supply circuit, and is characterized by further comprising an EMI circuit, wherein the EMI circuit is connected in parallel to one side of an input end of the power supply circuit, the EMI circuit comprises an inductor L1, a piezoresistor RV1, a capacitor C2 and a capacitor C1, the capacitor C1 and the capacitor C2 are connected in parallel to two ends of the inductor L1, the capacitor C1 is close to one side of the power supply circuit, the capacitor C2 is close to one side of an external power supply, and the piezoresistor RV1 is connected in parallel to one side of the capacitor C2 close to the external power supply.
Preferably, the power supply circuit comprises a rectifying circuit and a step-down voltage stabilizing circuit; the input end of the rectifying circuit is connected with an external power supply, and the output end of the rectifying circuit is connected with the voltage-reducing and voltage-stabilizing circuit; the rectification circuit is a full-wave rectification bridge BR1; the voltage-reducing and voltage-stabilizing circuit comprises a resistor R1, a resistor R2, a triode Q1, a resistor R7, a resistor R8, a triode Q2, a resistor R11, a resistor R14, a triode Q3, a voltage-stabilizing tube D1, a capacitor C3, a capacitor C8, a transient suppression diode TVS2, a capacitor C9, a capacitor C14, a voltage-stabilizing chip VOT1 and a capacitor C15, wherein the capacitor C3 is connected in parallel to the output end of the rectifying circuit, one ends of the resistor R1 and the resistor R2 are connected with the negative electrode of the output end of the rectifying circuit, the resistor R1, the resistor R7, the resistor R11 and the voltage-stabilizing tube D1 are sequentially connected in series, one end of the voltage-stabilizing tube D1 is connected with the positive electrode of the rectifying circuit, one end of the resistor R2, the resistor R8, the triode Q2, the resistor R14, the triode Q3 and the capacitor C8 are sequentially connected in series, one end of the capacitor C8 is connected with the positive electrode of the output end of the rectifying circuit, the base of the triode Q1 is connected with the intermediate node of the resistor R1 and the resistor R7, one end of the base of the resistor R7 is connected with the intermediate node of the resistor R7, one end of the resistor R7 is connected with the intermediate node of the resistor R11 and the intermediate node of the resistor C1, one end of the other end is connected with the intermediate node of the capacitor C9 and the other end of the capacitor C9 is sequentially connected with the output of the capacitor C1 and the intermediate node is connected with the output of the capacitor C9.
The voltage acquisition circuit comprises a resistor R3, a resistor R4, a resistor R5, a resistor R9, a resistor R12, a capacitor C4 and a transient suppression diode TVS1, wherein the resistor R3 is connected with a power circuit, the other end of the resistor is connected with the resistor R4 in series, the resistor R4 is connected with the resistor R5 in series, the resistor R5 is connected with the resistor R9 in series, the resistor R9 is connected with the resistor R12 in series, the resistor R12 is connected with the capacitor C4 in parallel, the other end of the transient suppression diode TVS1 is grounded, and a node between the resistor R9 and the resistor R12 provides a signal to the control circuit.
Preferably, the control circuit comprises a control chip U1, a capacitor C6, a capacitor C7, a resistor R15 and a capacitor C10, wherein a third pin of the control chip U1 is connected with the output end of the voltage acquisition circuit, an eighth pin of the control chip U1 and a nineteenth pin of the control chip U1 are grounded, one end of the capacitor C6 and the capacitor C7 which are connected in parallel is connected with a twentieth pin of the control chip U1, the other end of the capacitor C6 is grounded, and an intermediate node of the resistor R15 and the capacitor C10 is connected with the first pin of the control chip U1. Preferably, the control circuit comprises a control chip U1, a capacitor C6 and a capacitor C7, wherein a third pin of the control chip U1 is connected with the output end of the voltage acquisition circuit, an eighth pin of the control chip U1 and a nineteenth pin of the control chip U1 are grounded, one end of the capacitor C6 and the capacitor C7 which are connected in parallel is connected with a twentieth pin of the control chip U1, the other end of the capacitor C6 is grounded, a seventh pin of the control chip U1 is connected with the output end of the temperature acquisition circuit, and an intermediate node of a resistor R15 and a capacitor C10 is connected with a first pin of the control chip U1.
Preferably, the temperature acquisition circuit comprises a thermistor R6, a resistor R10, a resistor R13 and a capacitor C5, wherein one end of the thermistor R6, the resistor R10 and the resistor R13 which are connected in series is connected with a constant power supply, the other end of the thermistor is grounded, the capacitor C5 is connected in parallel at two ends of the resistor R13, the thermistor R6 is tightly attached to the coil, and a connecting wire between the resistor R10 and the resistor R13 is connected with the control circuit.
Preferably, the driving circuit comprises a driving chip U2, a capacitor C12, a capacitor C11, a resistor R17, a resistor R18, a capacitor C13, a resistor R16 and a diode D2, wherein the input end of the driving chip U2 is connected with the control circuit, the power end of the driving chip U2 is connected with one end of the capacitor C12 and one end of the capacitor C11 after being connected in parallel, the other end of the capacitor C12 and the other end of the capacitor C11 after being connected in parallel are grounded, the grounding ground of the driving chip U2 is grounded, the output end of the driving chip U2 is connected with one end of a resistor R17, the other end of the resistor R17 is connected with one end of a switching element and the resistor R18, the other end of the resistor R18 is connected with the positive electrode of the diode D2 after passing through the capacitor C13 and the resistor R16, the coils are connected with the two ends of the diode D2 in parallel, and the positive electrode of the diode D2 is connected with the switching element.
The invention also provides a contactor coil voltage control method, which comprises the following steps:
Acquiring the current input power supply voltage;
acquiring the current coil temperature, and acquiring the current coil resistance based on the current coil temperature according to the corresponding relation between the coil temperature and the coil resistance;
when the contactor is held, a coil holding voltage is obtained based on a coil current when the contactor is held, a current holding duty ratio is obtained based on a current power supply voltage and the coil holding voltage, and according to the holding duty ratio, voltages at two ends of a coil of the contactor are regulated, so that the contactor is in a reliable holding state.
Preferably, the coil start voltage is obtained based on a coil current at the time of start-up and based on a current power supply voltage and the coil start voltage, a current start duty ratio is obtained based on the current power supply voltage and the coil start voltage, and the voltage at both ends of the coil of the contactor is adjusted according to the start duty ratio, so that the contactor operates.
Preferably, the coil temperature is obtained by a thermistor in close contact with the coil.
The control circuit receives the current power supply voltage acquired by the voltage acquisition circuit, adjusts the duty ratio according to the current voltage signal to output a control signal, calculates the value of the duty ratio by acquiring the current voltage, drives the switching element to change the voltage of the coil of the contactor, realizes the starting and the maintaining of the coil, and achieves the basically constant voltage at two ends of the coil under different voltages, thereby stabilizing the average value of the voltage at two ends of the coil, having wider working voltage range of the coil, simple and compact circuit structure, low coil power consumption and low cost.
Further, the contactor control circuit provided by the invention further comprises a temperature acquisition circuit, wherein the temperature acquisition circuit is used for acquiring the temperature of the coil, the control circuit receives the current power supply voltage acquired by the voltage acquisition circuit and the current temperature of the coil acquired by the temperature acquisition circuit, the control circuit adjusts the duty ratio according to the current power supply voltage signal and the current temperature of the coil so as to output a control signal, the switching element is driven to change the voltage of the coil of the contactor, the starting and the holding of the coil are realized, the voltage at two ends of the coil is basically constant, the average value of the voltage at two ends of the coil is stable, the control circuit adjusts the duty ratio according to the current power supply voltage signal and the current temperature of the coil so as to output the control signal, the contactor control circuit is more stable and reliable in performance, the working voltage range of the coil is wider, the circuit structure is simple and compact, the coil power consumption is low, and the cost is low.
Drawings
FIG. 1 is a block diagram of one embodiment of a contactor control circuit of the present invention;
FIG. 2 is a block diagram of another embodiment of the contactor control circuit of the present invention;
FIG. 3 is a partial circuit diagram of the power circuit of the present invention;
FIG. 4 is a specific circuit diagram of the voltage acquisition circuit of the present invention;
FIG. 5 is a circuit diagram of a control circuit according to one embodiment of the invention;
FIG. 6 is a circuit diagram of a control circuit according to another embodiment of the present invention;
FIG. 7 is a circuit diagram of a drive circuit of the present invention;
FIG. 8 is a partial circuit diagram of a voltage step-down and stabilizing circuit of the present invention;
fig. 9 is a partial circuit diagram of the voltage step-down and stabilizing circuit of the present invention.
Detailed Description
Specific embodiments of the contactor control circuit and contactor coil voltage control method of the present invention are further described below in conjunction with the examples presented in figures 1 through 9. The contactor control circuit contactor coil voltage control method of the present invention is not limited to the description of the following embodiments.
The contactor control circuit comprises a power supply circuit, a voltage acquisition circuit, a control circuit, a driving circuit, a switching element and a coil, wherein the input end of the power supply circuit is connected with an external power supply for taking electricity, the output end of the power supply circuit is connected with the voltage acquisition circuit, the control circuit, the switching element and the coil to supply power for the voltage acquisition circuit, the control circuit, the switching element and the coil, the input end of the voltage acquisition circuit is connected with the power supply circuit and is used for acquiring the current power supply voltage signal of the power supply circuit, the input end of the control circuit is connected with the output end of the voltage acquisition circuit and is used for receiving the current power supply voltage signal acquired by the voltage acquisition circuit, the control circuit is further used for adjusting the duty ratio according to the current voltage signal to output a control signal, the input end of the driving circuit is connected with the output end of the control circuit, the driving circuit is connected with the switching element and receives the control signal sent by the control circuit to control the switching element to be turned on and off, the switching element is connected with the coil, and the on/off of the switching element controls the voltage at two ends of the coil.
The control circuit of the contactor comprises a power supply circuit, a voltage acquisition circuit, a control circuit, a driving circuit, a switching element and a coil, wherein the control circuit receives the current power supply voltage acquired by the voltage acquisition circuit, and the control circuit adjusts the duty ratio according to the current power supply voltage so as to output a control signal, drives the switching element to change the voltage of the coil of the contactor, realizes the starting and the holding of the coil, and achieves the purpose that the voltages at two ends of the coil are basically constant under different power supply voltages, so that the average value of the voltages at two ends of the coil is stable, the working voltage range of the coil is wider, the circuit structure is simple and compact, the power consumption of the coil is low, and the cost is low.
As shown in fig. 3, the contactor control circuit of the present invention further includes an EMI circuit. The EMI circuit is connected in parallel at one side of the input end of the power supply circuit, and comprises an inductor L1, a piezoresistor RV1, a capacitor C2 and a capacitor C1, wherein the capacitor C1 and the capacitor C2 are connected in parallel at two ends of the inductor L1, the capacitor C1 is close to one side of the power supply circuit, the capacitor C2 is close to one side of an external power supply, and the piezoresistor RV1 is connected in parallel at one side of the capacitor C2 close to the external power supply. The EMI circuit can filter the interference of high-frequency pulse of an external power grid to the power supply, and simultaneously reduces the electromagnetic interference of the switching power supply to the outside.
As shown in fig. 3, 8 and 9, the power supply circuit of the invention comprises a rectifying circuit and a step-down voltage stabilizing circuit; the input end of the rectifying circuit is connected with an external power supply, and the output end of the rectifying circuit is connected with the step-down voltage stabilizing circuit; the rectifying circuit is a full-wave rectifying bridge BR1; the voltage-reducing and voltage-stabilizing circuit comprises a resistor R1, a resistor R2, a resistor R7, a resistor R9, a triode Q2, a resistor R11, a resistor R14, a triode Q3, a triode D1, a capacitor C3, a capacitor C8, a transient suppression diode TVS2, a capacitor C9, a capacitor C14, a voltage-stabilizing chip VOT1 and a capacitor C15, wherein the capacitor C3 is connected in parallel to the output end of the rectifying circuit, one ends of the resistor R1 and the resistor R2 are connected with the negative electrode of the output end of the rectifying circuit, the resistor R1, the resistor R7, the resistor R11 and the voltage-stabilizing diode D1 are sequentially connected in series, one end of the triode Q2Q 1, the triode Q1, the resistor R8, the triode Q2, the resistor R14, the triode Q3 and the capacitor C8 are sequentially connected in series, one end of the capacitor C8 is connected with the positive electrode of the output end of the rectifying circuit, the base electrode of the resistor R1 and the intermediate node of the resistor R7 is connected with the intermediate node of the resistor R7, the base electrode of the triode Q2 and the intermediate node of the resistor R11 is connected with the capacitor C11 and the intermediate node of the capacitor C9 and the capacitor C9 is sequentially connected with the other end of the voltage-stabilizing chip, the base electrode of the capacitor C1 and the capacitor C11 is connected with the capacitor C9 and the intermediate node of the capacitor C9 is sequentially connected with the voltage-stabilizing chip, the other end of the capacitor C1 is connected with the voltage-stabilizing chip and the capacitor C9 is connected with the voltage-stabilizing capacitor C1 and the voltage-stabilizing capacitor C9 in parallel to the voltage-stabilizing node is connected with the voltage-stabilizing node. The power supply circuit adopts a voltage-reducing and voltage-stabilizing circuit composed of a resistor, a triode and a diode, and can also be a DC-DC voltage-reducing circuit or an LDO voltage-reducing circuit.
As shown in FIG. 4, the voltage acquisition circuit of the present invention comprises a resistor R3 connected with a power supply circuit, a resistor R4 connected in series with the other end of the voltage acquisition circuit, a resistor R4 connected in series with a resistor R5, a resistor R5 connected in series with a resistor R9, a resistor R9 connected in series with a resistor R12, a resistor R12 connected in parallel with a capacitor C4, a transient suppression diode TVS1 connected in parallel with the resistor R12 and the capacitor C4, and a node between the resistor R9 and the resistor R12 providing a signal to a control circuit. The voltage acquisition circuit is used for acquiring a current power supply voltage signal output by the power supply circuit.
As shown in FIG. 6, the control circuit comprises a control chip U1, a capacitor C6 and a capacitor C7, wherein a third pin of the control chip U1 is connected with the output end of the voltage acquisition circuit, an eighth pin of the control chip U1 and a nineteenth pin of the control chip U1 are grounded, one end of the capacitor C6 and the capacitor C7 which are connected in parallel is connected with a twentieth pin of the control chip U1, the other end of the capacitor C6 is grounded, and a middle node of a resistor R15 and a capacitor C10 is connected with the first pin of the control chip U1. The control circuit of the invention adopts a singlechip or a special driving chip.
As shown in FIG. 7, the driving circuit comprises a driving chip U2, a capacitor C12, a capacitor C11, a resistor R17, a resistor R18, a capacitor C13, a resistor R16 and a diode D2, wherein the input end of the driving chip U2 is connected with the control circuit, the power end of the driving chip U2 is connected with one end of the capacitor C12 and one end of the capacitor C11 after being connected in parallel, the other end of the capacitor C12 and the other end of the capacitor C11 after being connected in parallel are grounded, the grounding ground of the driving chip U2 is grounded, the output end of the driving chip U2 is connected with one end of a resistor R17, the other end of the resistor R17 is connected with one end of a switching element and the resistor R18, the other end of the resistor R18 is connected with the anode of the diode D2 after passing through the capacitor C13 and the resistor R16, the coil is connected with the two ends of the diode D2 in parallel, and the anode of the diode D2 is connected with the switching element. The driving chip U2 can be a driving chip with the model of FAN3111E, and the driving circuit of the invention adopts a special driver and can also be formed by discrete devices.
For example, the switching element is a MOS transistor Q4, and a power transistor, an IGBT, or the like may be used.
The following describes the operation of the contactor control circuit of the present invention in connection with fig. 1,3, 6,7,8, 9:
After the contactor control circuit is connected, the control circuit compares the minimum starting voltage value required by the coil with the current sampling power voltage value by detecting the rectified power voltage value.
When the rectified power supply voltage value is larger than the minimum starting voltage value of the coil, the ratio of the minimum starting voltage of the coil to the rectified power supply voltage is used as a starting duty ratio, the voltage at the two ends of the coil of the contactor is regulated according to the starting duty ratio, the power tube is driven to be conducted for a certain time after passing through the driving circuit, so that the contactor acts, the power tube is converted into a smaller holding duty ratio to enable the average value of the voltages at the two ends of the coil to be lower, the small holding voltage is provided, the reliable holding state of the contactor is met, the ratio of the coil holding voltage to the rectified power supply voltage is used as the holding duty ratio, the voltage at the two ends of the coil of the contactor is regulated according to the holding duty ratio, and the smaller holding duty ratio of the coil is regulated according to the change of the rectified voltage, so that the average value of the voltages at the two ends of the coil is stable. The coil minimum starting voltage value, and the coil holding voltage are known values. Of course, the start duty cycle and the hold duty cycle may be calculated in other ways than by using the ratio of the minimum start voltage of the coil and the hold voltage of the coil to the rectified voltage, respectively.
When the rectified voltage value is lower than a preset closing value, the control circuit closes the duty ratio output, the power tube is in a cut-off state, the coil has no maintenance voltage, and the contactor is in a cut-off state.
Fig. 2 is a schematic structural diagram of another contactor control circuit according to the present invention.
The contactor control circuit comprises a power supply circuit, a voltage acquisition circuit, a control circuit, a driving circuit, a switching element, a temperature acquisition circuit and a coil, wherein the input end of the power supply circuit is connected with an external power supply for taking electricity, the output end of the power supply circuit is connected with the voltage acquisition circuit, the control circuit, the switching element and the coil to supply power for the voltage acquisition circuit, the control circuit, the switching element and the coil, the input end of the voltage acquisition circuit is connected with the power supply circuit and is used for acquiring the current power supply voltage signal of the power supply circuit, the input end of the control circuit is connected with the output end of the voltage acquisition circuit and is used for receiving the current power supply voltage acquired by the voltage acquisition circuit, the temperature acquisition circuit is connected with the coil and is used for acquiring the temperature of the coil, the control circuit is used for sending the acquired temperature signal of the coil to the control circuit according to the current power supply voltage and the current temperature of the coil, the control circuit is further used for adjusting the duty ratio to output the control signal, the input end of the driving circuit is connected with the output end of the control circuit is connected with the switching element, the driving circuit is used for receiving the control signal sent by the control circuit, the switching element is connected with the switching element, and the switching element is turned on and off the switching element is connected with the two ends of the control element.
The contactor control circuit comprises a power supply circuit, a voltage acquisition circuit, a control circuit, a driving circuit, a switching element, a temperature acquisition circuit and a coil, wherein the control circuit receives the current power supply voltage acquired by the voltage acquisition circuit and the current temperature of the coil acquired by the temperature acquisition circuit, and adjusts the duty ratio according to the current power supply voltage and the current temperature of the coil so as to output a control signal, the switching element is driven to change the voltage of the coil of the contactor, the starting and the maintaining of the coil are realized, the voltage at two ends of the coil is basically constant, the average value of the voltage at two ends of the coil is stable, the control circuit adjusts the duty ratio according to the current power supply voltage and the current temperature of the coil so as to output a control signal, the contactor control circuit performance is more stable and reliable, the coil working voltage range is wider, the circuit structure is simple and compact, the coil power consumption is low, and the cost is low.
As shown in fig. 2, the temperature acquisition circuit is connected with the coil and used for acquiring the temperature of the coil, and the output end of the temperature acquisition circuit is connected with the control circuit and used for sending the acquired temperature signal of the coil to the control circuit.
As shown in FIG. 5, the control circuit comprises a control chip U1, a capacitor C6 and a capacitor C7, wherein a third pin of the control chip U1 is connected with the output end of the voltage acquisition circuit, an eighth pin of the control chip U1 and a nineteenth pin of the control chip U1 are grounded, one end of the capacitor C6 and the capacitor C7 which are connected in parallel is connected with a twentieth pin of the control chip U1, the other end of the capacitor C7 is grounded, a seventh pin of the control chip U1 is connected with the output end of the temperature acquisition circuit, and a middle node of a resistor R15 and a capacitor C10 is connected with a first pin of the control chip U1. The control chip U1 adopts a singlechip.
As shown in FIG. 5, the temperature acquisition circuit comprises a thermistor R6, a resistor R10, a resistor R13 and a capacitor C5, wherein the singlechip acquires the voltage drop generated by the resistor R13, one end of the thermistor R6, the resistor R10 and the resistor R13 which are connected in series is connected with a 5V constant power supply, the other end of the thermistor is grounded, the capacitor C5 is connected in parallel at two ends of the resistor R13, the thermistor R6 is tightly attached to a coil, a connecting line between the resistor R10 and the resistor R13 is connected with the control circuit, the resistor R10 and the resistor R13 are voltage dividing resistors, and the singlechip acquires the voltage drop generated by the resistor R13. Obviously, the temperature acquisition circuit can also be realized by adopting other temperature sensors, and the temperature of the coil is acquired by the temperature sensors.
In the embodiment shown in fig. 2, the power supply circuit, the voltage acquisition circuit, and the driving circuit may be the same circuit as in the embodiment shown in fig. 1, or may be different circuits.
The working principle of the contactor control circuit of the present invention is described below with reference to fig. 2,3, 4, 5, 6, 7, 8, 9:
after the contactor control circuit is connected, the control circuit obtains a rectified power supply voltage value through the voltage acquisition circuit, and the minimum starting voltage value required by the coil is compared with the sampled current power supply voltage value.
When the current power supply voltage value is larger than the minimum starting voltage value of the coil, the ratio of the minimum starting voltage of the coil to the power supply voltage is used as a starting duty ratio, the power tube is driven to be conducted for a certain time after passing through the driving circuit, and then the power tube is converted into a smaller holding duty ratio, so that the average value of the two ends of the coil is lower, and the contactor is in a reliable holding state. The holding duty ratio of the smaller maintenance coil is adjusted along with the voltage change after rectification and the temperature change of the coil, so that the average value of the voltages at two ends of the coil is stable. When the temperature of the coil changes, the control circuit reads the temperature of the coil through the temperature acquisition circuit, calculates the resistance of the coil at the moment, and comprehensively calculates the duty ratio by combining the input power voltage value at the moment. The thermistor is closely attached to the coil, the temperature of the coil is transferred to the thermistor so as to change the resistance value of the thermistor, the input power supply voltage of a circuit formed by the thermistor and the voltage dividing resistor is unchanged, when the resistance value of the thermistor changes along with the temperature, the voltage drop of the voltage dividing resistor has a corresponding relation with the temperature, so that the temperature of the coil is obtained, the temperature of the coil has a proportional corresponding relation with the resistance of the coil, when the temperature rises, the resistance becomes larger, and the corresponding relation between the temperature of the coil and the resistance of the coil is obtained through multiple tests. The coil resistance is written into the singlechip at normal temperature, the singlechip of the circuit switching-on control circuit reads the input voltage of the power supply circuit, when the input voltage reaches a starting voltage threshold value, starting current is calculated according to I=U/R, the voltage at two ends of the coil can obtain an ideal value through adjusting the duty ratio, after starting, the average value at two ends of the coil is lower through changing into a smaller holding duty ratio, the small holding voltage is provided, the contactor is in a reliable holding state, when the temperature of the coil is increased during holding, the coil resistance is increased, the coil holding voltage is obtained based on the coil current when the coil resistance is maintained, the ratio of the coil holding voltage to the input power supply voltage is taken as the holding duty ratio, and the voltage at two ends of the coil is increased through increasing the duty ratio, so that the coil current is ensured to be constant. On the contrary, the temperature of the coil is reduced, the resistance of the coil is reduced, the coil current when the resistance of the coil is maintained is obtained to obtain the coil holding voltage, the coil holding voltage is reduced, the voltage at two ends of the coil is reduced by reducing the duty ratio, the constant coil current is ensured, and the stable starting power and the stable holding power of the contactor coil at different temperatures are ensured.
When the rectified voltage value is lower than a preset closing value, the control circuit closes the duty ratio output, the power tube is in a cut-off state, the coil has no maintenance voltage, and the contactor is in a cut-off state.
In the embodiment, after the voltage acquisition circuit detects the power supply voltage, the magnitude of the PWM duty ratio is changed according to the magnitude of the power supply voltage, so that the voltage control of the coil is realized, and the action characteristic of the contactor is finished. The method has the defects that the coil resistance can be increased along with the environment temperature or the heating of the product, the duty ratio in the prior art PWM is not changed under the condition of the same input voltage, so that the coil current is reduced, and the actuation force of the contactor is reduced, so that the action characteristic of the contactor is changed. According to the invention, the temperature of the coil is acquired by the temperature acquisition circuit, so that temperature compensation control is realized, when the temperature rises, the coil resistance becomes larger, the PWM duty ratio is also changed, and thus the voltage at two ends of the coil is improved, the current in the coil is close to that before the temperature rises, and the attraction force of the contactor is ensured to be close to the attraction force under different temperatures of the same voltage, and the action characteristic is consistent. ( The minimum coil start voltage is the voltage that just causes the contactor to operate. Voltages above this minimum start-up voltage may be used to operate them, which may also be referred to as start-up voltages. The start-up voltage of the product identification is typically higher than the minimum start-up voltage. )
Based on the embodiment of the contactor control circuit, the invention further provides a contactor coil voltage control method, which comprises the following steps:
Acquiring the current input power supply voltage;
acquiring the current coil temperature, and acquiring the current coil resistance based on the current coil temperature according to the corresponding relation between the coil temperature and the coil resistance;
When the contactor is started, coil starting voltage is obtained based on coil current when the contactor is started, current starting duty ratio is obtained based on current power supply voltage and the coil starting voltage, and voltage at two ends of a coil of the contactor is regulated according to the starting duty ratio so that the contactor acts;
When the contactor is held, a coil holding voltage is obtained based on a coil current when the contactor is held, a current holding duty ratio is obtained based on a current power supply voltage and the coil holding voltage, and the voltage at both ends of the coil of the contactor is regulated according to the holding duty ratio, so that the contactor is in a reliable holding state.
The power supply voltage can be obtained based on the voltage acquisition circuit, namely the rectified voltage, the coil temperature can be obtained based on the temperature sampling circuit, which can be a temperature sensor or a thermistor. The coil current at the starting time and the coil current at the holding time are both known values, the holding duty ratio can be obtained based on the ratio of the coil holding voltage to the power supply voltage, other calculation modes can be adopted, the corresponding relation between the coil temperature and the coil resistance is a known value, and the coil current at the purchasing time can be obtained through a supplier or through experiments. The start-up may be performed in the manner of embodiment one irrespective of the coil temperature, and the hold-up may be performed in consideration of the current power supply voltage and the coil temperature output hold-up duty ratio.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.
Claims (8)
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| WO2021111656A1 (en) * | 2019-12-03 | 2021-06-10 | 三菱電機株式会社 | Electromagnetic coil drive circuit |
| CN112233935B (en) * | 2019-12-30 | 2022-03-29 | 蜂巢能源科技有限公司 | Contactor drive device and system |
| CN111969850A (en) * | 2020-08-28 | 2020-11-20 | 深圳市朗科智能电气股份有限公司 | Solenoid valve boosting and protecting circuit capable of controlling working mode |
| CN112187228B (en) * | 2020-09-30 | 2024-12-06 | 贵州天义电器有限责任公司 | A constant current pulse width modulation circuit for contactor coil |
| CN117276002A (en) * | 2023-08-30 | 2023-12-22 | 浙江正泰电器股份有限公司 | Control circuit and control method of contactor |
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| CN101188173A (en) * | 2007-07-19 | 2008-05-28 | 王有元 | Secure universal contactor |
| CN206421993U (en) * | 2016-12-22 | 2017-08-18 | 上海比亚迪有限公司 | A kind of relay coil drive circuit controlled based on PWM ripples |
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