阅读说明：本技术 一种路灯控制电路及其控制方法 (Street lamp control circuit and control method thereof ) 是由 向亚飞 陈宋文 肖迪凡 游万海 于 2020-11-26 设计创作，主要内容包括：本发明涉及一种路灯控制电路及其控制方法,控制电路包括：控制器、译码器、自耦变压器、多个接触器和路灯,译码器设有输入端和多个输出端,自耦变压器的绕组上设有多个输入触头和一个输出触头,任意两个输入触头对应的变压器变比均不相同,接触器的个数与输入触头的个数相同,且多个接触器与多个输入触头一一对应,接触器的个数还与译码器的输出端的个数相同,且多个接触器与译码器的多个输出端一一对应,各个输入触头分别通过对应的接触器的主触点连接至电源,自耦变压器的输出触头与路灯电连接,译码器的各个输出端分别与对应的接触器的辅助触点电连接,译码器的输入端与控制器电连接。本发明的路灯控制电路不会产生谐波,且结构简单。(The invention relates to a street lamp control circuit and a control method thereof, wherein the control circuit comprises: the controller, the decoder, autotransformer, a plurality of contactors and street lamp, the decoder is equipped with input and a plurality of output, be equipped with a plurality of input contacts and an output contact on autotransformer's the winding, the transformer transformation ratio that two arbitrary input contacts correspond is all inequality, the number of contactor is the same with the number of input contact, and a plurality of contactors and a plurality of input contact one-to-one, the number of contactor still is the same with the number of the output of decoder, and a plurality of output one-to-one of a plurality of contactors and decoder, each input contact is connected to the power through the main contact of the contactor that corresponds respectively, autotransformer's output contact is connected with the street lamp electricity, each output of decoder is connected with the auxiliary contact electricity of the contactor that corresponds respectively, the input and the controller electricity of. The street lamp control circuit of the invention can not generate harmonic waves and has simple structure.)

1. A street lamp control circuit, comprising: the device comprises a controller, a decoder, an autotransformer, a plurality of contactors and a street lamp, wherein the decoder is provided with an input end and a plurality of output ends, a plurality of input contacts and an output contact are arranged on a winding of the autotransformer, the transformation ratios of any two transformers corresponding to the input contacts are different, the number of the contactors is the same as that of the input contacts, the contactors are in one-to-one correspondence with the input contacts, the number of the contactors is also the same as that of the output ends of the decoder, the contactors are in one-to-one correspondence with the output ends of the decoder, the input contacts of the autotransformer are respectively connected to a power supply through corresponding main contacts of the contactors, the output contacts of the autotransformer are electrically connected with the street lamp, and the output ends of the decoder are respectively electrically connected with corresponding auxiliary contacts of the contactors, and the input end of the decoder is electrically connected with the controller.

2. The streetlamp control circuit of claim 1, further comprising a plurality of amplification circuits, wherein the number of the amplification circuits is the same as the number of the output ends of the decoder, the plurality of amplification circuits correspond to the plurality of output ends of the decoder one to one, and each output end of the decoder is connected to the corresponding auxiliary contact of the contactor through the corresponding amplification circuit.

3. The streetlamp control circuit of claim 2, wherein the amplifying circuit comprises a transistor, a diode and a resistor, wherein a collector of the transistor is electrically connected to an anode of the diode, a cathode of the diode is electrically connected to a dc power supply, the resistor is connected in parallel to the diode, a base of the transistor is electrically connected to an output terminal of the corresponding decoder, and an emitter of the transistor is electrically connected to an auxiliary contact of the corresponding contactor.

4. The streetlamp control circuit of claim 1, further comprising a real-time clock device for providing real-time, wherein the real-time clock device is electrically connected to the input of the controller.

5. The streetlamp control circuit of claim 4, further comprising an electric quantity detection circuit for detecting a voltage across the streetlamp and/or a current flowing through the streetlamp, wherein an output end of the electric quantity detection circuit is electrically connected to an input end of the controller.

6. The street lamp control circuit according to claim 5, wherein the electric quantity collecting circuit comprises a voltage transformer, a current transformer and an electric quantity metering device, the detection end of the voltage transformer and the detection end of the current transformer are respectively connected with two ends of the street lamp, the output end of the voltage transformer and the output end of the current transformer are respectively electrically connected with the input end of the electric quantity metering device, and the output end of the electric quantity metering device is electrically connected with the input end of the controller.

7. The streetlamp control circuit of claim 6, further comprising a memory, wherein the memory is used for storing the power signal collected by the power detection circuit, and the memory is electrically connected to the controller.

8. The streetlamp control circuit of any one of claims 1 to 7, further comprising a carrier communication device electrically connected to the controller.

9. A street lamp control method, based on the street lamp control circuit as claimed in any one of claims 1 to 8, comprising a real-time clock device electrically connected with an input terminal of the controller, the street lamp control method comprising:

acquiring real-time date and real-time output by the real-time clock device;

comparing the real-time date with a plurality of preset date fields respectively, and determining the current date field corresponding to the real-time date in all the date fields, wherein each date field corresponds to a plurality of time periods respectively;

comparing the real-time with a plurality of time periods corresponding to the current date period respectively, and determining the current time period corresponding to the real-time in all the time periods, wherein the street lamp is provided with a corresponding input voltage in each time period;

and controlling the corresponding contactor to pull in according to the input voltage corresponding to the current time period.

10. The streetlamp control method according to claim 9, further comprising an electric quantity detection circuit for detecting a voltage across the streetlamp, wherein an output end of the electric quantity detection circuit is electrically connected to an input end of the controller, the streetlamp is provided with a corresponding voltage threshold range in each time period, and different input voltages are provided for the streetlamp when different contactors are closed, and the streetlamp control method further comprises:

acquiring real-time voltages at two ends of the street lamp detected by the electric quantity detection circuit;

determining whether the real-time voltage is within the voltage threshold range corresponding to the current time period;

if yes, no action is taken;

if the real-time voltage is larger than the voltage threshold range, controlling a currently closed contactor to be opened, and controlling the contactor corresponding to any input voltage with a voltage value smaller than the real-time voltage to be closed;

and if the real-time voltage is smaller than the voltage threshold range, controlling the currently closed contactor to be switched off, and controlling the contactor corresponding to any input voltage with the voltage value larger than the real-time voltage to be switched on.

Technical Field

The invention relates to the technical field of intelligent control, in particular to a street lamp control circuit and a control method thereof.

Background

As is well known, the street lamps are important road infrastructure and play an important role in beautifying cities and guaranteeing road traffic safety, and with the continuous advance of city construction, the number of the street lamps is continuously increased, the power consumption of the street lamps is also higher and higher, and in order to save energy, the power consumption of the street lamps is usually reduced by controlling the voltage of the street lamps in the prior art.

At present, the chopper principle of silicon controlled rectifier is often used, and the voltage sine wave input by a power grid is chopped through the conduction angle of a thyristor or silicon controlled rectifier, so that the average value of output voltage is reduced, and the purpose of controlling voltage is realized. However, the chopping can cause the output voltage not to realize sine wave output, a large amount of harmonic waves can appear, harmonic pollution is caused to a power grid system, and the damage is great.

Disclosure of Invention

The invention aims to solve the technical problem of how to reduce harmonic waves in a circuit and provides a street lamp control circuit and a control method thereof.

The technical scheme for solving the technical problems is as follows:

in a first aspect, the present invention provides a street lamp control circuit, including: the device comprises a controller, a decoder, an autotransformer, a plurality of contactors and a street lamp, wherein the decoder is provided with an input end and a plurality of output ends, a plurality of input contacts and an output contact are arranged on a winding of the autotransformer, the transformation ratios of any two transformers corresponding to the input contacts are different, the number of the contactors is the same as that of the input contacts, the contactors are in one-to-one correspondence with the input contacts, the number of the contactors is also the same as that of the output ends of the decoder, the contactors are in one-to-one correspondence with the output ends of the decoder, the input contacts of the autotransformer are respectively connected to a power supply through corresponding main contacts of the contactors, the output contacts of the autotransformer are electrically connected with the street lamp, and the output ends of the decoder are respectively electrically connected with corresponding auxiliary contacts of the contactors, and the input end of the decoder is electrically connected with the controller.

The street lamp control circuit has the beneficial effects that: the controller outputs a control signal, the decoder converts the control signal into multi-path output to respectively control the contactors to be switched on or switched off, when one contactor is switched on, the input end of the autotransformer is connected with a power supply, the autotransformer transforms voltage to provide power for the street lamp, and different input contacts correspond to different transformer transformation ratios, so that different contactors are switched on, and different input voltages can be provided for the street lamp. According to the technical scheme, the contactors are controlled to be closed or opened, so that the transformer transformation ratio of the autotransformer is adjusted, the voltages at two ends of the street lamp can be adjusted according to needs, the output of the autotransformer is a sine wave signal, harmonic waves cannot be generated, and the structure is simple.

The number of the amplifying circuits is the same as that of the output ends of the decoder, the amplifying circuits are in one-to-one correspondence with the output ends of the decoder, and the output ends of the decoder are connected to the corresponding auxiliary contacts of the contactor through the corresponding amplifying circuits.

The beneficial effects of the further scheme are as follows: the amplifying circuit amplifies the signal output by the decoder, so that the signal can drive the contactor to pull in, and the switching of the input voltage grade of the autotransformer is realized.

Further, the amplifying circuit comprises a triode, a diode and a resistor, wherein a collector of the triode is electrically connected with an anode of the diode, a cathode of the diode is electrically connected with a direct current power supply, the resistor is connected with the diode in parallel, a base of the triode is electrically connected with an output end of the decoder correspondingly, and an emitter of the triode is electrically connected with an auxiliary contact of the contactor correspondingly.

Further, the real-time clock device is used for providing real-time and is electrically connected with the input end of the controller.

The beneficial effects of the further scheme are as follows: the real-time clock device is used for providing accurate real-time, and is convenient for controlling the voltage at two ends of the street lamp according to the real-time.

The street lamp further comprises an electric quantity detection circuit, the electric quantity detection circuit is used for detecting the voltage at the two ends of the street lamp and/or the current flowing through the street lamp, and the output end of the electric quantity detection circuit is electrically connected with the input end of the controller.

The beneficial effects of the further scheme are as follows: the electric quantity detection circuit is used for detecting the voltage at two ends of the street lamp or the current flowing through the street lamp, and can adjust the input voltage of the street lamp according to the detected voltage or current, so that the increase of power consumption caused by the overvoltage or overcurrent of the street lamp is avoided.

Furthermore, the electric quantity acquisition circuit comprises a voltage transformer, a current transformer and an electric quantity metering device, the detection end of the voltage transformer and the detection end of the current transformer are respectively connected with the two ends of the street lamp, the output end of the voltage transformer and the output end of the current transformer are respectively electrically connected with the input end of the electric quantity metering device, and the output end of the electric quantity metering device is electrically connected with the input end of the controller.

Further, still include the memory, the memory is used for storing the electric quantity signal that electric quantity detection circuitry gathered, the memory with the controller electricity is connected.

The beneficial effects of the further scheme are as follows: the memory is used for storing the electric quantity signal detected by the electric quantity detection circuit and the like.

Further, the controller also comprises a carrier communication device which is electrically connected with the controller.

The beneficial effects of the further scheme are as follows: and a carrier communication device is arranged, so that the controller can conveniently communicate with equipment such as an upper computer.

In a second aspect, the present invention provides a street lamp control method, based on the street lamp control circuit, where the street lamp control circuit includes a real-time clock device, the real-time clock device is electrically connected to an input end of the controller, and the street lamp control method includes:

acquiring real-time date and real-time output by the real-time clock device;

comparing the real-time date with a plurality of preset date fields respectively, and determining the current date field corresponding to the real-time date in all the date fields, wherein each date field corresponds to a plurality of time periods respectively;

comparing the real-time with a plurality of time periods corresponding to the current date period respectively, and determining the current time period corresponding to the real-time in all the time periods, wherein the street lamp is provided with a corresponding input voltage in each time period;

and controlling the corresponding contactor to pull in according to the input voltage corresponding to the current time period.

The street lamp control method has the beneficial effects that: the method comprises the steps of firstly determining a current date section corresponding to a real-time date, wherein each date section corresponds to a plurality of time sections, then determining a current time section corresponding to the real-time, determining the street lamp input voltage of the real-time due to the fact that each time section corresponds to one input voltage, and finally controlling a corresponding contactor to be closed according to the input voltage to provide the corresponding input voltage for the street lamp. By controlling the input voltage at the two ends of the street lamp in different time periods and different time periods, the accurate control of the voltage of the street lamp can be realized, and the power consumption of the street lamp is reduced.

Further, the street lamp control circuit further includes an electric quantity detection circuit for detecting voltages at two ends of the street lamp, an output end of the electric quantity detection circuit is electrically connected with an input end of the controller, the street lamp is provided with a corresponding voltage threshold range in each time period, and different input voltages are provided for the street lamp when different contactors are closed, and the street lamp control method further includes:

acquiring real-time voltages at two ends of the street lamp detected by the electric quantity detection circuit;

determining whether the real-time voltage is within the voltage threshold range corresponding to the current time period;

if yes, no action is taken;

if the real-time voltage is larger than the voltage threshold range, controlling the currently closed contactor to be opened, and controlling the contactor corresponding to any input voltage with a voltage value smaller than the real-time voltage to be closed;

and if the real-time voltage is smaller than the voltage threshold range, controlling the currently closed contactor to be switched off, and controlling the contactor corresponding to any input voltage with the voltage value larger than the real-time voltage to be switched on.

Drawings

Fig. 1 is a schematic circuit connection diagram of a street lamp control circuit according to an embodiment of the invention;

FIG. 2 is a schematic diagram of the autotransformer connection according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of an amplifying circuit according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a controller according to an embodiment of the present invention;

fig. 5 is a schematic flow chart of a street lamp control method according to an embodiment of the present invention.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

As shown in fig. 1 and fig. 2, a street lamp control circuit provided in an embodiment of the present invention includes: the device comprises a controller, a decoder, an autotransformer, a plurality of contactors and a street lamp, wherein the decoder is provided with an input end and a plurality of output ends, a plurality of input contacts and an output contact are arranged on a winding of the autotransformer, the transformation ratios of any two transformers corresponding to the input contacts are different, the number of the contactors is the same as that of the input contacts, the contactors are in one-to-one correspondence with the input contacts, the number of the contactors is also the same as that of the output ends of the decoder, the contactors are in one-to-one correspondence with the output ends of the decoder, the input contacts of the autotransformer are respectively connected to a power supply through corresponding main contacts of the contactors, the output contacts of the autotransformer are electrically connected with the street lamp, and the output ends of the decoder are respectively electrically connected with corresponding auxiliary contacts of the contactors, and the input end of the decoder is electrically connected with the controller.

In this embodiment, the controller outputs a control signal, the decoder converts the control signal into a plurality of paths of outputs, and the contactors are controlled to be closed or opened respectively. According to the technical scheme, the contactors are controlled to be closed or opened, so that the transformer transformation ratio of the autotransformer is adjusted, the voltages at two ends of the street lamp can be adjusted according to needs, the output of the autotransformer is a sine wave signal, harmonic waves cannot be generated, and the structure is simple.

Specifically, the autotransformer is a transformer in which a primary coil and a secondary coil are on the same winding, a plurality of input contacts and one output contact are led out from the winding of the autotransformer of the embodiment, the controller may adopt a single chip microcomputer of type AT89C51, and the decoder may adopt a two-four decoder of type 74LS155, and may be electrically connected with pins P1.4 and P1.5 of the single chip microcomputer of AT89C 51. The input contacts of the autotransformer are respectively connected to a power supply through corresponding contactors, for example, the autotransformer shown in fig. 2 has four input contacts, one of which is connected with a live wire L through a contactor KM1, one of which is connected with a live wire L through a contactor KM2, one of which is connected with a live wire L through a contactor KM3, one of which is connected with a live wire L through a contactor KM4, N is a zero line, four input contacts respectively correspond to different transformer transformation ratios, the output voltages of the autotransformer are different from each other when different contactors are communicated, assuming that the power supply corresponding to L is 220V, when the contactor KM1 is closed, the input voltage of the autotransformer is 220V, when the contactor KM2 is closed, the output of the autotransformer is 93% of the rated voltage, namely 204V, when the contactor KM3 is closed, the output of the autotransformer is 88% of the rated voltage, namely 193, the output of the autotransformer is 83 percent of the rated voltage, namely 182V, and the output voltage is the input voltage of the street lamp after the transformation of the autotransformer.

Preferably, the contactor further comprises a plurality of amplifying circuits, the number of the amplifying circuits is the same as that of the output ends of the decoder, the amplifying circuits correspond to the output ends of the decoder one to one, and the output ends of the decoder are connected to the corresponding auxiliary contacts of the contactor through the corresponding amplifying circuits respectively.

Specifically, the amplifying circuit amplifies the signal output by the decoder, so that the signal can drive the contactor to pull in, and the switching of the input voltage grade of the autotransformer is realized.

Preferably, as shown in fig. 3, the amplifying circuit includes a transistor Q, a diode VD, and a resistor R, wherein a collector of the transistor Q is electrically connected to an anode of the diode VD, a cathode of the diode VD is electrically connected to a 24V dc power supply, the resistor R is connected to the diode VD in parallel, a base of the transistor Q is electrically connected to the corresponding output terminal of the decoder, and an emitter of the transistor Q is electrically connected to the corresponding auxiliary contact of the contactor.

Preferably, as shown in fig. 4, the controller further comprises a real-time clock device for providing real-time, and the real-time clock device is electrically connected with the input end of the controller.

Specifically, the real-time clock device can adopt a real-time clock chip with a model of DS1302, and can be electrically connected with pins P1.6 and P1.7 of the AT89C51 single chip microcomputer, and the real-time clock device is used for providing accurate real-time, so that the voltage AT two ends of the street lamp can be controlled according to the real-time, for example: the real-time clock device can be used for setting the turn-on time period and the turn-off time period of the street lamp, the controller controls the street lamp to be turned on in the turn-on time period and controls the street lamp to be turned off in the turn-off time period.

Preferably, the street lamp further comprises an electric quantity detection circuit, the electric quantity detection circuit is used for detecting the voltage at two ends of the street lamp and/or the current flowing through the street lamp, and the output end of the electric quantity detection circuit is electrically connected with the input end of the controller.

Specifically, the electric quantity detection circuit is used for detecting voltages at two ends of the street lamp or current flowing through the street lamp, and can adjust the input voltage of the street lamp according to the detected voltages or currents, so that the phenomenon that the power consumption is increased due to overvoltage or overcurrent of the street lamp is avoided.

Preferably, the electric quantity acquisition circuit comprises a voltage transformer, a current transformer and an electric quantity metering device, the detection end of the voltage transformer and the detection end of the current transformer are respectively connected with the two ends of the street lamp, the output end of the voltage transformer and the output end of the current transformer are respectively electrically connected with the input end of the electric quantity metering device, and the output end of the electric quantity metering device is electrically connected with the input end of the controller.

Specifically, voltage transformer is used for gathering the voltage AT street lamp both ends, current transformer is used for gathering the electric current that flows through the street lamp, electric quantity metering device can adopt the three-phase electric energy measurement chip that the model is ATT7028, can be connected with the P1.1 of AT89C51 singlechip, P1.2 and P1.3 pin electricity, be applicable to three-phase three-wire and three-phase four-wire circuit, can measure each looks and the active power who closes the looks, the active function volume, simultaneously can also measure each phase current, voltage virtual value, power factor, the phase angle, parameters such as frequency, can also convert the voltage signal that voltage transformer gathered and the current signal that current transformer gathered into the digital signal that the controller can handle.

Preferably, the electric quantity detection circuit further comprises a memory, the memory is used for storing the electric quantity signal collected by the electric quantity detection circuit, and the memory is electrically connected with the controller.

Specifically, the memory can adopt a ferroelectric memory with the model number of AT24C02, can be electrically connected with pins P2.6 and P2.7 of an AT89C51 singlechip, is not easy to lose stored data, and can provide inquiry of data such as active power history records and the like.

Preferably, the controller further comprises a carrier communication device electrically connected with the controller.

Specifically, the carrier communication device may employ a communication chip of a model LM1893, the LM1893 chip is a modulation-demodulation chip of an FSK (Frequency-shift keying) system, can implement reliable half-duplex power line communication of serial data, has two working modes of transmitting data and receiving data, can be compatible with an AT89C51 single chip microcomputer, and has a modulation-demodulation data input terminal DATAIN electrically connected to a serial output interface TXD of an AT89C51, and an output terminal DATAOUT electrically connected to a serial input interface RXD of an AT89C 51. The TX/RX transmitting and receiving control end of the LM1893 is electrically connected with the P1.0 end of the single chip microcomputer, the high level is in a transmitting state, and the low level is in a receiving state. After receiving the external data information, the controller judges the message header and the address of the received data, and executes corresponding action when the message header is correct and the address is the local address, and enters a sending state after the execution.

As shown in fig. 5, a street lamp control method provided in an embodiment of the present invention is based on the street lamp control circuit, where the street lamp control circuit includes a real-time clock device, the real-time clock device is electrically connected to an input end of the controller, and the street lamp control method includes:

100, acquiring real-time date and real-time output by the real-time clock device;

200, comparing the real-time date with a plurality of preset date fields respectively, and determining a current date field corresponding to the real-time date in all the date fields, wherein each date field corresponds to a plurality of time periods respectively;

300, comparing the real-time with a plurality of time periods corresponding to the current date period respectively, and determining the current time period corresponding to the real-time in all the time periods, wherein each time period of the street lamp is provided with a corresponding input voltage;

and 400, controlling the corresponding contactor to pull in according to the input voltage corresponding to the current time period.

In the embodiment, the current date section corresponding to the real-time date is determined, each date section corresponds to a plurality of time sections, the current time section corresponding to the real-time is determined, the street lamp input voltage of the real-time can be determined due to the fact that each time section corresponds to one input voltage, and finally the corresponding contactor is controlled to be closed according to the input voltage to provide the corresponding input voltage for the street lamp. By controlling the input voltage at the two ends of the street lamp in different time periods and different time periods, the accurate control of the voltage of the street lamp can be realized, and the power consumption of the street lamp is reduced.

Specifically, due to the influence of the rotation and revolution of the earth, sunrise and sunset times and sunshine times of various positions with different longitudes and latitudes on the earth are different, and a year of the corresponding position may be divided into a plurality of date segments according to the sunrise and sunset times, for example, 1 month 11 to 3 months 12 days are divided into a first date segment, 3 months 13 to 5 months 12 days are divided into a second date segment, 5 months 13 to 7 months 13 days are divided into a third date segment, 7 months 14 to 9 months 12 days are divided into a fourth date segment, 9 months 13 to 11 months 8 days are divided into a fifth date segment, and 11 months 9 to 1 month 10 days are divided into a sixth date segment. The starting and stopping time of the street lamps in each date section can be set to be consistent with the sunrise and sunset time, the street lamps are opened during sunset, and the street lamps are closed during sunrise. The lighting time of the night street lamp can be divided into a plurality of time periods according to the traffic flow at night, for example, if the traffic flow at 21:30 corresponds to a peak in the daytime, the time period is divided into a first time period, if the traffic flow at 21:30 to 23:30 corresponds to a normal traffic flow, the time period is divided into a second time period, and if the traffic flow at 23:30 to 2:00 corresponds to a valley in the traffic flow, the time period is divided into a third time period. The voltage at the two ends of the street lamp is adjusted according to different time periods, for example, when the traffic flow is high in the first time period, the relay KM1 is controlled to suck, so that the street lamp works under the full pressure of 220V, and the illumination of the road surface is ensured; when the normal traffic flow is in the second time period, the relay KM1 is controlled to be switched off, the relay KM2 is controlled to be switched on, and the street lamp is controlled to work under 204V; and when the traffic flow is low in the third time period, the control relay KM2 is switched off, the relay KM3 is switched on, and the street lamp is controlled to work at 193V. Aiming at different time periods, the time-sharing control voltage works under the corresponding voltage, the street lamp voltage is accurately controlled, the power consumption of the street lamp can be reduced as much as possible under the condition of ensuring the road illumination, and the street lamp is energy-saving and environment-friendly.

Preferably, the street lamp control circuit further includes an electric quantity detection circuit for detecting voltages at two ends of the street lamp, an output end of the electric quantity detection circuit is electrically connected to an input end of the controller, the street lamp is provided with a corresponding voltage threshold range in each time period, and different input voltages are provided for the street lamp when different contactors are closed, and the street lamp control method further includes:

acquiring real-time voltages at two ends of the street lamp detected by the electric quantity detection circuit;

determining whether the real-time voltage is within the voltage threshold range corresponding to the current time period;

if yes, no action is taken;

if the real-time voltage is larger than the voltage threshold range, controlling the currently closed contactor to be opened, and controlling the contactor corresponding to any input voltage with a voltage value smaller than the real-time voltage to be closed;

and if the real-time voltage is smaller than the voltage threshold range, controlling the currently closed contactor to be switched off, and controlling the contactor corresponding to any input voltage with the voltage value larger than the real-time voltage to be switched on.

Specifically, the voltage detected by the power detection circuit is compared with the stored corresponding voltage threshold range, and when the voltage is higher than the voltage threshold range, the contactor with the corresponding low output voltage is switched, for example, from KM1 to KM 2; when the voltage is lower than the voltage threshold range, the contactor is switched to the corresponding high output voltage, such as from KM3 to KM 2.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.