CN117747319A

CN117747319A - Three-phase system and method for controlling switching on and off of contact based on phase load characteristics

Info

Publication number: CN117747319A
Application number: CN202211111048.0A
Authority: CN
Inventors: 卢向东; 王接兆
Original assignee: Schneider Electric Industries SAS
Current assignee: Schneider Electric Industries SAS
Priority date: 2022-09-13
Filing date: 2022-09-13
Publication date: 2024-03-22

Abstract

A three-phase system for controlling switching on and off of contacts based on phase load characteristics and a control method thereof are provided. The three-phase system includes: the phase voltage sampling unit is used for acquiring the waveform of the phase voltage at the input side of the phase contact; the load voltage sampling unit is used for acquiring the waveform of the phase voltage at the output side of the phase contact; the phase load characteristic identification unit is used for determining the phase load characteristic of each phase according to the waveforms acquired by the phase voltage sampling unit and the load voltage sampling unit, determining the switching-on risk and the switching-off risk of each phase based on the phase load characteristic of each phase, determining the switching-on phase and the switching-off phase of each phase at the new time according to the switching-on risk and the switching-off risk of each phase, and controlling the contacts of the three-phase system to switch on and off according to the switching-on phase and the switching-off phase of each phase at the new time. The three-phase system and the control method thereof can improve the service life of the contact of the three-phase opening and closing product and reduce the fusion welding risk of the contact.

Description

Three-phase system and method for controlling switching on and off of contact based on phase load characteristics

Technical Field

The present application relates to a three-phase system and a contact control method thereof, and more particularly, to a three-phase system and a method for controlling switching on and off of contacts based on phase load characteristics.

Background

With the development of terminal power distribution, the requirement on terminal power distribution is not only traditional trip protection, but also remote control or automatic switching on/off protection and the like, such as iCT, OUPA, RCA and the like. Because of the greater real-time and cost advantages of power relays over RCA electrically operated control of the main switch (e.g., miniature circuit breaker MCB), a number of applications are used in terminal power distribution applications, as shown at K1 in fig. 1. Three-phase systems distribute power at terminals (most of the load is Lx-N based) and the load characteristics are different for each phase, such as household and similar uses, and different load characteristics for each phase may result in different life of each phase contact of the power relay. In general, a significant portion of the reason for the impact on contact life is the frequent opening and closing. When the contacts are switched on and off, the contacts are welded and cannot be closed due to contact bounce, arc discharge and the like, and particularly when the contacts with resistive heating loads (such as incandescent lamps) are switched on and when the contacts with inductive loads (such as motors and compressors) are switched off. From the perspective of failed three-phase automatic opening and closing products, most of failures are caused by fusion welding or abnormality of one phase.

However, for the automatic switching-on/off products which can be independently controlled by each phase of contact of a single-phase system or a three-phase system, zero-crossing switching-on/off can be adopted to reduce the voltage and current of switching-on so as to improve the service life of the contact of the power relay, but for the automatic switching-on/off products which simultaneously act on the three-phase contacts of the three-phase system, because the three-phase contacts simultaneously act, switching-on/off of one phase at a zero-crossing point can only be realized, and switching-off voltages of other two phases are near a peak point, arc discharge and bouncing are still easy.

The switching control of the contacts of most three phases is random, so that the service life of the contacts is shortened or the contacts are welded due to the fact that electric arcs generated by bouncing during switching of the contacts are avoided or reduced, and the service life of the contacts can be prolonged to a certain extent by increasing the mechanical pressure of the contacts. However, the current solutions have the following drawbacks: 1) Lifting the contact mechanical pressure means that a larger power supply is required to drive the coil of the power relay, which presents a challenge for compact end products; 2) The mechanical pressure of the contact is improved, contact bounce during contact closing can be avoided, but the influence of arc discharge guide on the service life of the contact during opening can not be reduced.

Therefore, there is a need for a three-phase system and a contact control method thereof that improves the contact life of a three-phase opening and closing product and reduces the risk of contact fusion welding.

Disclosure of Invention

Technical problem

The service life of the contact of the three-phase opening and closing product is prolonged, and the fusion welding risk of the contact is reduced.

Technical proposal

The three-phase system and the method improve the service life of the contact of the three-phase switching-on/off product by controlling the switching-on/off time sequence of the contact based on the phase load characteristic. Specifically, the application provides a three-phase system and a contact control method thereof, wherein the characteristics of phase load are identified through characteristics such as voltages at two ends of a contact when the phase load is switched on and switched off, and the phases of the switching on and switching off of the phase load are controlled based on the characteristics of the phase load.

According to one aspect of the present disclosure, there is provided a three-phase system for controlling switching on and off of contacts based on phase load characteristics, including: the phase voltage sampling unit is used for acquiring the waveform of the phase voltage at the input side of the phase contact; the load voltage sampling unit is used for acquiring the waveform of the phase voltage at the output side of the phase contact; the phase load characteristic identification unit is used for determining the phase load characteristic of each phase according to the waveforms acquired by the phase voltage sampling unit and the load voltage sampling unit, determining the switching-on risk and the switching-off risk of each phase based on the phase load characteristic of each phase, determining the switching-on phase and the switching-off phase of each phase at the new time according to the switching-on risk and the switching-off risk of each phase, and controlling the contacts of the three-phase system to switch on and off according to the switching-on phase and the switching-off phase of each phase at the new time.

In one embodiment, the phase load characteristic identifying unit determines the closing phase and the opening phase of each phase of the new time including: each phase is switched on according to a preset switching-on phase, the current switching-on contact bouncing time and the current switching-on contact bouncing amplitude are obtained according to waveforms obtained by a phase voltage sampling unit and a load voltage sampling unit, the switching-on risk of each phase is determined according to the obtained current switching-on contact bouncing time and the obtained contact voltage bouncing amplitude, the switching-on phase of each phase is determined according to the switching-on risk of each phase, each phase is switched off according to the preset switching-on phase, the current switching-off contact bouncing time and the current switching-off contact bouncing amplitude are obtained according to waveforms obtained by the phase voltage sampling unit and the load voltage sampling unit, the switching-off risk of each phase is determined according to the obtained current switching-off contact bouncing time and the obtained contact voltage bouncing amplitude, and the switching-off phase of each phase is determined according to the switching-off risk of each phase.

In one embodiment, the contacts of each phase of the three-phase system are ganged, and wherein the phase of that phase is optimized for the phase having a significantly higher risk of opening or closing than the other two phases.

In one embodiment, the three-phase system further includes a current sampling unit for acquiring a waveform of a current of each phase load, wherein the phase load characteristic identifying unit determines a closing phase and a opening phase of each phase newly, including: each phase is switched on according to a preset switching-on phase, phase load characteristics are identified according to phase differences of waveforms acquired by a phase voltage sampling unit and a current sampling unit and instantaneous currents of each phase during switching on, switching-on risk and switching-off risk of each phase are determined, the switching-on phase of each phase is determined according to the switching-on risk and switching-off risk of each phase, switching-off is performed according to the preset switching-off phase of each phase, phase load characteristics are identified according to phase differences of waveforms acquired by the phase voltage sampling unit and the current sampling unit and currents of each phase during switching-off, switching-on risk and switching-off risk of each phase are determined, and switching-off phase of each phase is determined according to the switching-on risk and the switching-off risk of each phase.

In one embodiment, the contacts of each phase of the three-phase system are ganged, and wherein the closing phase of that phase is optimized for the phase with the greatest instantaneous current at closing, and wherein the opening phase of that phase is optimized for the phase with the voltage leading the current at opening.

In one embodiment, the phase control unit determines the closing time and the opening time of the contacts of each phase through waveforms of voltages acquired by the phase voltage sampling unit and the load voltage sampling unit.

In one embodiment, the three-phase system further comprises a relay coil driving unit, wherein the phase control unit triggers the relay coil driving unit to realize switching on and switching off of each phase of contacts according to the phase load characteristic of each phase identified by the phase load characteristic identification unit and the switching on time and switching off time of each phase of contacts determined by the phase control unit after a certain delay.

According to another aspect of the present disclosure, there is provided a method of controlling contact opening and closing of a three-phase system based on a phase load characteristic, including: acquiring a waveform of a phase voltage at an input side of the phase contact; acquiring a waveform of a phase voltage at an output side of the phase contact; the phase load characteristic of each phase is determined according to the acquired waveform, the switching-on risk and the switching-off risk of each phase are determined based on the phase load characteristic of each phase, the switching-on phase and the switching-off phase of each phase are determined according to the switching-on risk and the switching-off risk of each phase, and the contacts of each phase of the three-phase system are controlled to switch on and off according to the switching-on phase and the switching-off phase of each phase.

In one embodiment, determining the closing and opening phases of each phase of the new time includes: each phase is switched on according to a preset switching-on phase, the current switching-on contact bouncing time and the contact voltage bouncing amplitude are obtained according to the obtained waveform, the switching-on risk of each phase is determined according to the obtained current switching-on contact bouncing time and the contact voltage bouncing amplitude, the switching-on phase of each phase is determined according to the switching-on risk of each phase, each phase is switched off according to the preset switching-on phase, the current switching-off contact bouncing time and the contact voltage bouncing amplitude are obtained according to the obtained waveform, the switching-off risk of each phase is determined according to the obtained current switching-off contact bouncing time and the contact voltage bouncing amplitude, and the switching-off phase of each phase is determined according to the switching-off risk of each phase.

In one embodiment, the method further comprises: acquiring a waveform of current of each phase of load, wherein determining a closing phase and a separating phase of each phase of the new time comprises: each phase is switched on according to a preset switching-on phase, phase load characteristics are identified according to the phase difference of the acquired waveforms and the instantaneous current of each phase during switching on, switching-on risk and switching-off risk of each phase are determined, the switching-on phase of each phase is determined according to the switching-on risk and switching-off risk of each phase, switching-off is performed according to the preset switching-off phase of each phase, phase load characteristics are identified according to the phase difference of the acquired waveforms and the current of each phase during switching-off, switching-on risk and switching-off risk of each phase are determined, and switching-off phase of each phase is determined according to the switching-on risk and switching-off risk of each phase.

In one embodiment, the closing time and opening time of the contacts of each phase are determined by the waveform of the acquired voltage.

In one embodiment, according to the identified phase load characteristic of each phase and the determined closing time and opening time of the contacts of each phase, a relay coil driving unit of the three-phase system is triggered after a certain delay to realize closing and opening of the contacts of each phase according to the closing phase and opening phase of each phase.

Advantageous effects

The switching-on/off phases of the phase load contacts are controlled through the identification of the load characteristics, the service lives of the contacts of the three-phase system are prolonged, and the contact fusion welding risk is reduced. And the instantaneous heavy current impact of re-electrifying and closing is reduced. Reduce the instant large voltage impact of opening the gate. The three-phase system and the method provided by the application not only can be used for automatic opening and closing products, but also can be used for remote control of opening and closing products, and are particularly suitable for the scene of simultaneous opening and closing of three-phase contacts.

Drawings

The various aspects, features and advantages of the disclosure will become more apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic circuit diagram of a typical application of a conventional three-phase system;

FIG. 2 is a circuit diagram illustrating a three-phase system according to an embodiment of the present disclosure;

fig. 3 and 4 are schematic diagrams illustrating a first manner in which the phase load characteristic identifying unit identifies the phase load characteristic and determines the opening/closing phase of each phase at a new time according to an embodiment of the present disclosure.

Fig. 5 and 6 are schematic diagrams showing a second mode in which the phase load characteristic identifying unit identifies the phase load characteristic and determines the opening/closing phase of each phase at a new time according to an embodiment of the present disclosure.

Fig. 7 is a schematic diagram showing a phase control unit controlling opening and closing of phase contacts in a specific phase according to an embodiment of the present disclosure.

Fig. 8 is a flowchart illustrating a contact control method of a three-phase system according to an embodiment of the present disclosure.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that in the drawings, identical or similar elements are indicated by identical or similar reference numerals as much as possible. Further, in describing the embodiments of the present disclosure, descriptions related to technical contents that are well known in the art and are not directly associated with the present disclosure will be omitted. Such unnecessary description is omitted so as to prevent obscuring the main idea of the present disclosure and to more clearly convey the main idea.

For the same reason, some elements may be enlarged, omitted, or schematically shown in the drawings. Furthermore, the size of each element does not fully reflect the actual size. In the drawings, identical or corresponding elements have identical reference numerals.

The advantages and features of the present disclosure and the manner in which they are accomplished will become apparent by reference to the embodiments that are described in detail below in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments set forth below, but may be implemented in various forms. The following examples are provided solely for the purpose of fully disclosing the present disclosure and informing those skilled in the art the scope of the present disclosure and are limited only by the scope of the appended claims. Features of the various embodiments described may be combined with or substituted for one another, unless expressly excluded or excluded depending on the context.

The application provides a three-phase system and a contact control method thereof, wherein the characteristics of phase load are identified through characteristics such as voltages at two ends of a contact when the phase load is switched on and switched off, and the switching on and switching off phases of the phase load are controlled based on the characteristics of the phase load.

Fig. 2 is a circuit diagram illustrating a three-phase system according to an embodiment of the present disclosure.

The function of the individual units in fig. 2 is as follows:

1) A Power Supply (Power Supply) unit converts the three-phase voltage of the Power grid to the voltages required by the relay driving unit and the micro control unit, such as 12V and 3.3V.

2) A phase voltage sampling (Line Voltage Sampling) unit acquires waveforms of phase voltages at the input side of the contact in real time, including waveforms of phase voltages at opening and closing.

3) A Current Sampling (Current Sampling) unit obtains a waveform of the Current of each phase load, which is an optional input to a phase load characteristic identification (Phase load characteristic identifying) unit, and may also be used to determine load characteristics.

4) A load voltage sampling (Load Voltage Sampling) unit acquires waveforms of phase voltages at the output sides of the contacts, including waveforms of phase voltages at opening and closing.

5) The Relay Coil driving (Relay Coil driving) unit is used for driving the power Relay to open or close.

6) The input of the switching-on and switching-off command (Close and Open Command) unit can come from tripping protection and reclosing signals generated by overvoltage and undervoltage, overload and electric leakage, and can also come from remote control signals such as I/O, wired and wireless communication and the like.

7) The phase load characteristic identifying (Phase load characteristic identifying) unit may identify the phase load characteristic and determine the opening and closing phase of each phase at a new time.

8) The Phase Control (Phase Control) unit is used for adjusting the opening and closing Phase of each Phase.

There are three ways in which the phase load characteristic identifying unit identifies the phase load characteristic and determines the opening/closing phase of each phase at a new time, which will be described in detail below.

The phase load characteristic identifying unit may identify the phase load characteristic by the mode one and determine the opening/closing phase of each phase at a new time.

Mode one: regarding switching on, each phase is switched on according to a preset switching-on phase, the current switching-on contact bounce time and the contact voltage bounce amplitude are obtained through waveforms obtained by a phase voltage sampling unit and a load voltage sampling unit, and each phase switching-on phase is determined according to the obtained current switching-on contact bounce time and the contact voltage bounce amplitude. The contact bounce time and the contact voltage bounce magnitude indirectly reflect the load characteristics. If the load is a pure resistive load, the switching-on current cannot be suddenly changed, and the switching-on bounce time is relatively short. In the case of inductive loads, the voltage bounce amplitude of the contacts is high due to the induced electromotive force. As shown in fig. 3, α11 is the current preset closing phase of L1, and corresponds to the contact bounce time tc1 and the contact voltage bounce amplitude vc1; α12 is the current preset closing phase of L2, corresponding to the contact bounce time tc2 and the contact voltage bounce amplitude vc2; α13 is the current preset closing phase of L3, corresponding to the contact bounce time tc3 and the contact voltage bounce amplitude vc3; α21 is the next preset closing phase of L1, α22 is the next preset closing phase of L2, and α23 is the next preset closing phase of L3.

The phase load characteristic identification unit comprises a switching-on contact phase regulator (Close contact phases regulator) which can find a phase with a switching-on risk obviously higher than other two phases according to the following formula (1), and optimize the switching-on phase of the phase in the new switching-on, namely, adjust the phase of the phase to reduce the contact bounce time and the contact voltage bounce amplitude.

Risk_ci is the switching Risk of each phase, wv is the switching contact voltage bounce amplitude weight, wt is the switching contact voltage bounce time weight, vci is the switching contact voltage bounce amplitude of each phase, tci is the switching contact voltage bounce time of each phase, wherein i represents the phase number, which is 1, 2 or 3.

Mode one: regarding opening, each phase is opened according to a preset opening phase, phase load characteristics are identified through waveforms acquired by the phase voltage sampling unit and the load voltage sampling unit, contact bounce time and contact voltage bounce amplitude of each phase opening are acquired, and each phase opening phase is determined according to the acquired contact bounce time and contact voltage bounce amplitude. As shown in fig. 4. 11 is L1 current preset opening phase, and corresponds to contact bounce time to1 and contact voltage bounce amplitude vo1; beta 12 is L2 and is the current preset opening phase, and corresponds to the contact bounce time to2 and the contact voltage bounce amplitude vo2; β13 is the current preset opening phase of L3, corresponding to the contact bounce time to3 and the contact voltage bounce amplitude vo3; β21 is the next preset opening phase of L1, β22 is the next preset opening phase of L2, and β23 is the next preset opening phase of L3.

The phase-separating contact phase regulator (Open contact phases regulator) included in the phase load characteristic identification unit can find a phase with a separating risk obviously higher than other two phases according to the following formula (2), and optimize the separating phase of the phase for the new separating, so that contact bounce and arcing time caused by induced electromotive force are reduced.

Risk_oi is the breaking Risk of each phase, wv is the breaking contact voltage bounce amplitude weight, wt is the breaking contact voltage bounce time weight, voi is the breaking contact voltage bounce amplitude of each phase, toi is the contact voltage bounce time of each phase, where i represents the phase number, and is 1, 2 or 3.

The new opening and closing phase control is a closed-loop control mode. For example, the risk of the L1 phase is highest, the original beta 11 is switched on at 65 degrees, and the new beta 21 is regulated downwards by 10 degrees, such as 55 degrees.

The phase load characteristic identifying unit may identify the phase load characteristic by the second mode and determine the opening/closing phase of each phase at a new time.

Mode two: regarding the closing, the phase voltage sampling unit and the current sampling unit combine to judge the phase difference of the voltage and the current and the closing instantaneous current to identify the characteristics of the phase load and determine the closing phase of each phase. The phase with the largest instantaneous current of the switching, which may be the load of an incandescent lamp, resistive heating, etc., optimizes the switching phase of the phase for the new switching, thereby reducing the starting current of the phase. As shown in fig. 5.γ11 is the current preset closing phase of L1, ic1 is the L1 closing current, PD1 is the L1 voltage current phase difference, and γ21 is the next preset closing phase of L1; gamma 12 is the current preset closing phase of L2, ic2 is the L2 closing current, PD2 is the L2 voltage current phase difference, and gamma 22 is the next preset closing phase of L2; gamma 13 is the current preset closing phase of L3, ic3 is the L3 closing current, PD3 is the L3 voltage current phase difference, and gamma 23 is the next preset closing phase of L3.

Mode two: regarding the opening, characteristics of the phase load are identified and the opening phase of each phase is newly determined based on the currents of the phases at the opening time in accordance with PD1, PD2, and PD 3. For the phase with the largest voltage leading current, the switching-off phase of the phase is optimized for the new switching-off, so that the contact bounce and the arcing time caused by induced electromotive force are reduced. As shown in fig. 6, δ11 is the current preset opening phase of L1, io1 is the opening current of L1, PD1 is the L1 voltage-current phase difference, and δ21 is the next preset opening phase of L1; delta 12 is the current preset opening phase of L2, io2 is the opening current of L2, PD2 is the voltage-current phase difference of L2, and delta 22 is the next preset opening phase of L2; delta 13 is the current preset opening phase of L3, io3 is the opening current of L3, PD3 is the phase difference of L3 voltage and current, and delta 23 is the next preset opening phase of L3.

In addition, the phase load characteristic identifying unit may identify the phase load characteristic and determine the opening/closing phase of each phase at a new time by means of the third method.

Mode three: the phase voltage sampling unit, the load voltage sampling unit and the current sampling unit are combined in a mode of one mode and two modes to identify phase load characteristics and determine the switching-on and switching-off phase of each new phase.

In addition, the contacts of each phase of the three-phase system provided by the application are linked, and the three contact control modes are particularly suitable for a scene that the three-phase contacts are simultaneously switched on.

For an automatic switching-on/off product which can be independently controlled by each phase of contact of a single-phase system or a three-phase system, zero-crossing switching-on/off can be adopted to reduce the voltage and current of switching-on, so that the service life of the contact of a power relay is prolonged, but for the automatic switching-on/off product which simultaneously acts on the three-phase contacts of the three-phase system, switching-on/off of one phase at a zero-crossing point can only be realized due to the simultaneous action of the three-phase contacts, and switching-on/off voltages of other two phases are near a peak point, arc starting and bouncing are still easy. In the three contact control modes of the application, the phase of the phase with the highest risk is optimized, so that the arc discharge and the bouncing of the three-phase contact reach the approaching level, the service lives of the three contacts of the three phases are consistent, and the situation that the phase is damaged firstly due to the highest risk is avoided.

Fig. 7 is an example in which the phase control unit controls the opening and closing of the phase contacts in a specific phase.

The phase control unit is used for adjusting the opening and closing phase of each phase. The phase control unit monitors the voltages of the phase voltage sampling unit and the load voltage sampling unit to determine the opening and closing time of each phase of contact, for example, the opening time of the contact, namely the time from the sending of a control signal to the driving of the contact by the contact coil, can be calculated through the sampling of the phase voltage and the load voltage. When the phase control unit receives signals from the switching-on and switching-off command unit, the relay coil driving unit is triggered after a certain delay according to the load characteristics of each phase identified by the phase load characteristic identification unit and the switching-on and switching-off time of the contact, so that switching-on and switching-off of the three-phase contact according to the required phase, namely the determined new switching-on and switching-off phase, are realized. For example, the phase control unit performs switching on and off of the zero crossing point of the L1 phase, as shown in fig. 7.

Fig. 8 is a flow chart of a contact control method of a three-phase system according to an embodiment of the present disclosure.

Judging whether a contact closing command is received, if the contact closing command is received, updating a target closing phase of each phase based on the phase load characteristic identification unit, and then calculating delay time for sending a closing signal to the relay coil driving unit. And judging whether the delay time is over, and if the delay time is over, sending a closing signal. Signals of phase voltage, load voltage and load current of each phase are acquired during contact closing, and then the phase load characteristic identification unit is updated based on signal analysis.

Next, it is determined whether a contact opening command is received, and if the contact opening command is received, the target opening phase of each phase is updated based on the phase load characteristic identification unit, and then the delay time for transmitting the opening signal to the relay coil driving unit is calculated. Whether the delay time is over or not is judged, and if the delay time is over, a brake-off signal is sent. Signals of a phase voltage, a load voltage, and a load current of each phase are acquired during contact opening, and then the phase load characteristic identification unit is updated based on signal analysis.

In summary, the phase load characteristic identifying unit identifies the voltage and the current at both ends of the contact at the last closing time. The phase load characteristic identification unit judges the load characteristic of the phase as an inductive load through signals of the voltage and the current at two ends of the contact, and adjusts the target closing phase of the phase to enable closing near a zero crossing point at the current closing moment, so that contact bounce is reduced. The phase load characteristic identification unit identifies the voltage and the current at both ends of the contact at the last switching-off time. The phase load characteristic recognition unit determines the load characteristic of the phase as an inductive load by signals of the voltage and the current at the two ends of the contact, and adjusts the target switching-off phase of the phase to switch off nearby with small magnetic flux variation at the current switching-off time, so that the influence of induced electromotive force on the contact is reduced.

Specific embodiments of the present disclosure have been shown and described above with reference to the accompanying drawings. The three-phase system and the contact control method thereof improve the service life of the contacts of the three-phase system and reduce the contact fusion welding risk.

The entirety of the hardware devices described in this disclosure, or components thereof, may be implemented by various suitable hardware means including, but not limited to FPGA, ASIC, soC, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

The block diagrams of circuits, devices, apparatuses, devices, systems referred to in this disclosure are by way of example only and are not intended to require or imply that connections, arrangements, and configurations must be made in the manner shown in the drawings. As will be appreciated by one of skill in the art, these circuits, devices, apparatus, devices, systems may be connected, arranged and configured in any manner so long as the desired purpose is achieved.

The embodiments set forth herein describe example configurations, methods, and apparatus in connection with the accompanying drawings and are not meant to represent all examples that may be implemented or within the scope of the claims. The term "exemplary" as used herein means "serving as an example, instance, or illustration," rather than "preferred" or "advantageous over other examples. The detailed description includes specific details for the purpose of providing an understanding of the described technology. However, the techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

Although this description contains specific implementation details, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features specific to particular embodiments of particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

It will be appreciated by persons skilled in the art that the above-described embodiments are merely examples and that various modifications, combinations, partial combinations and substitutions may be made to the embodiments of the present disclosure according to design requirements and other factors, provided that they fall within the scope of the appended claims or their equivalents, i.e., within the scope of the claims to be protected by the present disclosure.

Claims

1. A three-phase system for controlling opening and closing of contacts based on phase load characteristics, comprising:

the phase voltage sampling unit is used for acquiring the waveform of the phase voltage at the input side of the phase contact;

the load voltage sampling unit is used for acquiring the waveform of the phase voltage at the output side of the phase contact;

a phase load characteristic identifying unit that determines a phase load characteristic of each phase from waveforms acquired by the phase voltage sampling unit and the load voltage sampling unit, determines a closing risk and a opening risk of each phase based on the phase load characteristic of each phase, and determines a closing phase and an opening phase of each phase each new time according to the closing risk and the opening risk of each phase, and

and the phase control unit is used for controlling the contacts of the three-phase system to switch on and switch off according to the switching-on phase and the switching-off phase of each new phase.

2. The three-phase system according to claim 1, wherein the phase load characteristic identifying unit determining the closing phase and the opening phase of each phase at a new time includes:

each phase is switched on according to a preset switching-on phase, the current switching-on contact bounce time and the contact voltage bounce amplitude are obtained according to waveforms obtained by a phase voltage sampling unit and a load voltage sampling unit, the switching-on risk of each phase is determined according to the obtained current switching-on contact bounce time and the contact voltage bounce amplitude, the switching-on phase of each phase is determined according to the switching-on risk of each phase, and the switching-on phase of each phase is determined newly

Each phase is switched according to a preset switching-on phase, the current switching-on contact bounce time and the current switching-off contact bounce amplitude are obtained according to waveforms obtained by the phase voltage sampling unit and the load voltage sampling unit, the switching-on risk of each phase is obtained according to the obtained current switching-on contact bounce time and the contact voltage bounce amplitude, and the switching-on phase of each phase is determined according to the switching-on risk of each phase.

3. A three-phase system according to claim 2,

wherein the contacts of each phase of the three-phase system are linked, and

wherein the phase of the phase is optimized for the phase with a significantly higher risk of opening or closing than the other two phases.

4. The three-phase system according to claim 1, further comprising a current sampling unit for acquiring a waveform of a current of each phase load,

the phase load characteristic identification unit determines a closing phase and a separating phase of each phase newly, wherein the phase load characteristic identification unit comprises:

each phase is switched on according to a preset switching-on phase, phase load characteristics are identified according to phase differences of waveforms acquired by a phase voltage sampling unit and a current sampling unit and instantaneous currents of each phase during switching-on, switching-on risk and switching-off risk of each phase are determined, the switching-on phase of each phase is determined according to the switching-on risk and the switching-off risk of each phase, and

each phase is opened according to a preset opening phase, phase load characteristics are identified according to phase differences of waveforms acquired by the phase voltage sampling unit and the current sampling unit and currents of each phase during opening, closing risks and opening risks of each phase are determined, and opening phases of each phase are determined newly according to the closing risks and opening risks of each phase.

5. A three-phase system according to claim 4,

wherein the contacts of each phase of the three-phase system are linked, and

wherein, for the phase with the maximum instantaneous current in closing, the closing phase of the phase is optimized, and

wherein, for the phase of voltage leading current when opening the gate, the opening phase of the phase is optimized.

6. The three-phase system according to claim 1, wherein the phase control unit determines the closing time and the opening time of the contacts of each phase by waveforms of voltages acquired by the phase voltage sampling unit and the load voltage sampling unit.

7. The three-phase system according to claim 6, further comprising a relay coil driving unit,

the phase control unit triggers the relay coil driving unit to realize switching on and off of each phase of contacts according to the phase load characteristic of each phase identified by the phase load characteristic identification unit and the switching on time and switching off time of each phase of contacts determined by the phase control unit after a certain delay.

8. A method for controlling opening and closing of contacts of a three-phase system based on phase load characteristics, comprising:

acquiring a waveform of a phase voltage at an input side of the phase contact;

acquiring a waveform of a phase voltage at an output side of the phase contact;

determining a phase load characteristic of each phase from the acquired waveform, determining a closing risk and a opening risk of each phase based on the phase load characteristic of each phase, and determining a closing phase and an opening phase of each phase each new time according to the closing risk and the opening risk of each phase, and

and controlling the contacts of each phase of the three-phase system to switch on and switch off according to the switching-on phase and the switching-off phase of each phase.

9. The method of claim 1, wherein determining the closing phase and the opening phase of each phase of the new time comprises:

each phase is switched on according to a preset switching-on phase, the current switching-on contact bouncing time and the contact voltage bouncing amplitude are obtained according to the obtained waveform, the switching-on risk of each phase is determined according to the obtained current switching-on contact bouncing time and the contact voltage bouncing amplitude, the switching-on phase of each phase is determined according to the switching-on risk of each phase, and

each phase is switched according to a preset switching-on phase, the current switching-on contact bouncing time and the current switching-off contact bouncing amplitude are obtained according to the obtained waveforms, the switching-on risk of each phase is obtained according to the obtained current switching-on contact bouncing time and the obtained current switching-off contact bouncing amplitude, and the switching-on phase of each phase is determined according to the switching-on risk of each phase.

10. The method according to claim 9, wherein the method comprises,

wherein the contacts of each phase of the three-phase system are linked, and

11. The method of claim 8, further comprising: a waveform of the current of each phase of load is acquired,

wherein, determining the closing phase and the opening phase of each new phase comprises:

each phase is switched on according to a preset switching-on phase, phase load characteristics are identified according to the phase difference of the acquired waveforms and the instantaneous current of each phase during switching on, switching-on risk and switching-off risk of each phase are determined, the switching-on phase of each phase is determined according to the switching-on risk and switching-off risk of each phase, and

each phase is opened according to a preset opening phase, phase load characteristics are identified according to the phase difference of the acquired waveforms and currents of each phase during opening, closing risks and opening risks of each phase are determined, and opening phases of each phase are determined newly according to the closing risks and opening risks of each phase.

12. The method according to claim 11,

wherein the contacts of each phase of the three-phase system are linked, and

13. The method of claim 8, wherein the closing and opening times of the contacts of each phase are determined by waveforms of the acquired voltages.

14. The method of claim 13, wherein the relay coil driving unit of the three-phase system is triggered after a certain delay according to the identified phase load characteristic of each phase and the determined closing time and opening time of the contacts of each phase, so as to realize closing and opening of the contacts of each phase according to the closing phase and opening phase of each phase.