CN102299519A

CN102299519A - Switching switch circuit of alternating current capacitor

Info

Publication number: CN102299519A
Application number: CN201010210758XA
Authority: CN
Inventors: 王海
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-06-28
Filing date: 2010-06-28
Publication date: 2011-12-28

Abstract

The invention discloses a switching method and a switching switch circuit of an alternating current capacitor. A main relay contact protective circuit formed by a diode and an auxiliary relay is connected at two ends of a relay contact in parallel; at the duration of the conduction of the diode, the main relay contact is closed or disconnected, when the contact operates, surge electric current and contact fire striking can not happen, the withstand voltage endured by the throw-cut switch in disconnection corresponds to that of the switching switch of a relay, the error breakover phenomenon of an electronic switch can not be found, and the throw-cut speed corresponds to a controllable silicon; and the switch circuit has the characteristics of simple circuit, reliability in operation, low cost and rapid switching speed.

Description

AC capacitor fling-cut switch circuit

Technical field

Patent application of the present invention relates to a kind of AC capacitor fling-cut switch circuit, belongs to the electric switch field, belongs to electronic/mechanical combination switch field especially.

Background technology

AC capacitor is widely used in power factor of electric network compensation and electrical network filtering, will be connected with electrical network at any time according to the actual needs of electrical network or disconnect when AC capacitor is used in electrical network, i.e. the switching of so-called AC capacitor.At present commonly used have several schemes such as MSC (contactor, circuit breaker) switching, TSC (controllable silicon) switching and combination switch (controllable silicon and contactor paralleling switch) switching.The shortcoming of MSC switching is can't solve surge current that moment that capacitor and electrical network connect produces electrical network to be produced the influence of impacting and life of capacitors being produced, the way of surge current is to use the TSC switching when solving the AC capacitor switching at present, allow controllable silicon " operating passing zero ", promptly allow controllable silicon put conducting in no-voltage, but in fact because controllable silicon has the conducting dead angle, uncontrollable its realized the silicon controlled conducting at no-voltage point completely, and this switching mode requires to trigger accurately and the high cost that will increase circuits for triggering of reliability, on the characteristic of the anti-surge current of silicon controlled, controllable silicon is unsuitable for doing the switch of capacitive load in addition; Though the TSC switching has cost height, self-heating amount big and can increase the shortcoming of the harmonic current of electrical network, it is still the preferably selection of surge current in the time of can solving capacitor switching at present.The combination switch switching is a kind of scheme of switching circuit that combines the advantage of TSC switching and MSC switching, has the advantage that cost is low, switching moment surge current is little.The combination switch switching is to use controllable silicon as the transition electronic switch, but the phenomenon that controllable silicon can mislead when the dv/dt of anode voltage is very high will be burnt controllable silicon in case mislead.Be to adopt the capacitance-resistance absorption circuit to reduce dv/dt during general controllable silicon uses, thereby reduce the possibility that controllable silicon misleads, and can not adopt the method for series connection resistance-capacitance circuit to reduce dv/dt in the occasion of controllable silicon switching AC capacitor, because series resistance will increase the loss of fling-cut switch.So it is that TSC switching and combination switch switching scheme one is difficult to overcome a difficult problem that silicon controlled misleads, the TSC switching is that surge current burns the silicon controlled problem when selecting for use big controlled current silicon solution controllable silicon to mislead, but combination switch generally all is to use the less controllable silicon of rated current, because use the big controllable silicon of rated current will lose the low advantage of combination switch cost, and silicon controlled to mislead be the one of the main reasons that causes combination switch to lose efficacy.Mislead in order to reduce silicon controlled in the combination switch scheme, generally all select the higher controllable silicon of dv/dt value, but this has just reduced the probability that controllable silicon misleads, and can't tackle the problem at its root.In addition, the mislead surge current that produces of silicon controlled also has very big influence to the life-span and the electrical network of AC capacitor.Because the integrity problem of combination switch switching, the combination switch switching is actually a controversial switching scheme.Chinese patent application 200920179929.X discloses a kind of AC capacitor fling-cut switch circuit, also is the compound switch of a kind of electronics and mechanical switch, does not use controllable silicon as auxiliary switch.Before capacitor switching, need capacitor is charged, earlier capacitor discharge connection main relay contacts in parallel with diode when with the diode current flow of capacitors in series finished switching during switching, the ON time of diode is 5 milliseconds (50Hz alternating currents) to the maximum when each switching, because the restriction of discharge loop electronic switch electric current, the ON time of actual diode in the switching process be the 2-3 millisecond just, main relay will be finished the closure of contact in the 2-3 millisecond, this has proposed higher requirement for the manufacturing of main relay.

In sum, as seen except requiring occasion frequent, switching fast need use TSC switching scheme, general use occasion TSC switching compares not account for what advantage with the combination switch switching with the contactor switching, so in actual use, and a large amount of at present still contactor switchings that use.

Summary of the invention

The present invention proposes a kind of AC capacitor fling-cut switch circuit, avoided the shortcoming of MSC switching, TSC switching and combination switch switching, there are not surge current and contact sparking in the moment of fling-cut switch closed and disconnected, it is withstand voltage suitable with the contactor fling-cut switch that switch bears when disconnecting, and switching speed is suitable with the TSC switching.Have the reliability height, circuit is simple, with low cost and the fireballing characteristics of switching.

For achieving the above object, the present invention proposes following technology side's solution case: AC capacitor fling-cut switch circuit of the present invention is made up of main relay contacts protective circuit, main relay and single chip control module and is it is characterized in that: the main relay contacts protective circuit is composed in series by diode and auxiliary relay contact, is connected in parallel on the main relay contacts two ends; The contact of main relay with by the AC capacitor series connection of switching at the electrical network two ends; The time sequencing of the closed and disconnected of single chip control module control main relay and auxiliary relay.

The relay contact protection circuit of AC capacitor fling-cut switch circuit of the present invention can be the series connection of diode and electronic switch.Electronic switch can be controllable silicon, power MOS pipe, IGBT, high-voltage power triode etc.

AC capacitor fling-cut switch circuit of the present invention, single chip control module is powered by the capacitance decompression rectification filtering power.

AC capacitor fling-cut switch circuit of the present invention has switching speed piece, the characteristics of no surge current and non-relay contact sparking in the switching process, the switching speed of switch is identical with the TSC switching mode, almost do not have the loss of switch contact during the fling-cut switch operate as normal, prolong the life-span of switch contact greatly.The situation that switch misleads can not take place in the switch off period, prevented capacitor owing to moment huge charging current reduce life-span or damage.AC capacitor fling-cut switch circuit structure of the present invention is simple, cost is low and reliability is high.

Description of drawings

Fig. 1, AC capacitor fling-cut switch circuit theory Fig. 1 of the present invention;

Fig. 2, AC capacitor switching process electric current of the present invention, voltage oscillogram;

Fig. 3, AC capacitor fling-cut switch circuit theory Fig. 2 of the present invention;

Fig. 4, AC capacitor fling-cut switch circuit diagram of the present invention.

Specific embodiment

Fig. 1 is an AC capacitor fling-cut switch circuit diagram of the present invention.AC capacitor fling-cut switch circuit of the present invention is made up of three parts: the 1. protective circuit of main relay J1 contact K1: be to be connected in parallel on the diode D at main relay contacts K1 two ends and the series circuit of auxiliary relay J2 contact K2, the effect of this protective circuit is closed or prevent contact sparking or arcing when disconnecting at contact K1; 2. main relay J1: the contact K1 of main relay J1 is connected on by between switched capacitor and the electrical network; 3. single chip control module: be made up of single-chip microcomputer and peripheral circuit, its effect is the closed of control main relay J1 and auxiliary relay J2 contact or the time sequencing that disconnects.Shown in course of work Fig. 2 of AC capacitor fling-cut switch circuit of the present invention: during fling-cut switch circuit switching (switch closure), single chip control module is at first controlled the contact K2 closure of auxiliary relay J2, the selection of time of contact J2 closure is in t1 arrives the time period of t2, it in the time of t1, t2 the negative half period of alternating current, even contact J2 closure, diode D is in reverse bias always, diode by, do not have the contact K2 of electric current, spark phenomenon can not take place in the K2 course of action of contact by diode and relay J 2; Alternating current arrives t2 zero passage constantly; diode begins forward bias; diode D is with rapid conducting; the contact K1 of single chip control module control main relay J1 is at t3 closed constantly (t3 be alternating current zero point to any time between the peak value); in the process of the closure of relay contact K1 since diode be conducting; the voltage that contact K1 bears is the conducting voltage 0.7V of diode; so the power consumption that the contact K1 of relay J 1 bore in the moment of closure is very little, diode D has played the effect of relay contact protection.After the contact K1 closure of main relay J1,, finish the input electrical network process of AC capacitor with diode D short circuit, after the complete closure of K1, K2 closed or open not influence to K1.The shake of the contact K1 of main relay J1 is unavoidable in this capacitor input process; the moment diode D that disconnects in contact chatter is with conducting at any time; 0.7V voltage is only born in the contact, so can not strike sparks in the contact, this is the contact of protection relay to greatest extent.AC capacitor is moved back when throwing from electrical network, guarantee the contact K2 closure of auxiliary relay contact J2 earlier, be selected in t4 the opening time of the contact K1 of single chip control module control relay J1 in the time of t6, promptly between the negative peak and posivtive spike of alternating current, what diode D bore when contact K1 disconnected is the conducting at any time of forward (conducting) voltage, in case be that the K1 turn-off current flows through from diode immediately, the voltage that contact K1 bears when disconnecting is the forward voltage 0.7V of diode, so the contact the arcing phenomenon can not take place.The contact K1 disconnection back diode D of relay J 1 is conducting to t6 always and automatically shuts down constantly.Not conducting of diode D reverse bias in t6 arrives the time period of t7, the contact K2 of single chip control module control auxiliary relay J2 disconnects in the time of t7 at t6, promptly finished the throwing process of moving back of capacitor, t6 does not have electric current to pass through contact K2 in the time of t7, so contact K2 arcing can not take place when disconnecting.Current waveform by diode in the closing of contact and the disconnection process and the current waveform by main relay contacts are as shown in Figure 2.

If diode reverse connects among Fig. 1, AC capacitor fling-cut switch circuit of the present invention also can operate as normal, just corresponding the variation takes place in the time of the closed and disconnected of contact J2 and J1, and those skilled in the art can derive voluntarily by aforementioned, do not repeat them here.

After capacitor moves back throwing; the crest voltage that will keep electrical network on the capacitor; this voltage will discharge by the discharge resistance R that is connected in parallel on the capacitor two ends; for existing capacitor switching technology is that residual voltage on the requirement capacitor drops to when going to zero and could drop into capacitor once more; otherwise can cause the surge current when dropping into; and use AC capacitor switching circuit of the present invention; when capacitor once more during switching; owing on the capacitor residual voltage is arranged; diode can be in the zero crossing conducting of alternating current; but to wait until the automatic conducting of diode meeting when alternating voltage rises to the residual voltage that slightly surpasses on the capacitor; the contact of main relay is closed again behind diode current flow, just can realize the protection of diode pair main relay contacts.Known that moving back the time of throwing and dropping into once more just can calculate residual voltage on the capacitor, thereby can determine the time of relay contact closure, single-chip microcomputer is easy to realize this function.Use ac capacitor operation/cutting method of the present invention, can realize frequent, the switching fast of the capacitor that exchanges.

The what is called " operating passing zero " of AC capacitor operation/cutting method of the present invention and prior art is essentially different: the zero passage input of prior art is to allow the conducting of controllable silicon small change electrical voltage point, and operation/cutting method of the present invention is to allow the automatic conducting of diode in the alternating current zero passage.Operating passing zero needs the control circuit of more complicated to put conducting to guarantee controllable silicon in no-voltage; and AC capacitor operation/cutting method of the present invention is to add oppositely not conduction period closed auxiliary relay contact at the contact protection circuit; under the condition of 50Hz alternating current; the closure of auxiliary contact has 10 milliseconds time, and this is to realize very easily.The switching process of capacitor can be regarded as fling-cut switch with capacitor as in the load incoming transport electrical network, when having only the voltage that bears when the moment contact of switch conduction or electric current to be zero, the power consumption that switch contact bears is only minimum, the contact of mechanical switch can not be accurately in the conducting of zero-power point, and the mechanical contact turn on process is the shake that is accompanied by the contact, and mechanical contact is difficult to realize the zero-power conducting.TSC switching and combination switch switching all are that to bear voltage at controllable silicon anode and negative electrode be to trigger the controllable silicon conducting zero point to realize " zero-power " switching.Zero crossing triggers controllable silicon relatively still than what be easier to realize, and the variation owing to silicon controlled conducting dead angle and corresponding time parameter is difficult to realize so control the conducting of silicon control zero-cross point accurately.And the conducting of diode only needs anode voltage to be higher than condition of cathode voltage, does not need to trigger, so the condition of diode current flow has been howed than controllable silicon is simple, the speed of conducting is also fast than controllable silicon, and the cost of control circuit is also very low.

The contact K1 of relay must finish closing course when diode current flow, and relay contact closure (comprising the shake of contact) be need certain hour and certain error arranged, the ON time of diode is 5 milliseconds (50Hz alternating currents) when capacitor drops into, this proposes to compare higher requirement to the relay of selecting for use, action stabilization time of general relay contact is greater than this time, the relay that cooperates AC capacitor fling-cut switch circuit of the present invention to use needs special improvement, does not describe in detail in present patent application.

Auxiliary relay also can replace as shown in Figure 3 with power MOS pipe.In the K1 closed and disconnected process of the contact of main relay J1, conducting state is to guarantee that diode D at any time can conducting always to allow metal-oxide-semiconductor T1, and the Continuity signal of metal-oxide-semiconductor T1 is provided by single chip control module.Also can use electronic switches such as controllable silicon, IGBT or high-voltage three-pole pipe to substitute power MOS pipe; so this relay contact protection circuit can be diode and electronic switch series connection; electronic switch can be controllable silicon, power MOS pipe, IGBT, high-voltage power triode etc.

Relay in the AC capacitor fling-cut switch circuit of the present invention can be conventional DC or alternating current electromagnetic relay, magnetic latching relay, also can be the mechanical self-latching relay.Use the circuit power consumption after magnetic latching relay or mechanical self-latching relay can reduce relay contact closure.The relay that cooperates AC capacitor fling-cut switch circuit of the present invention to use should be able to satisfy the short and stable requirement of contact time of contact chatter time.

Fig. 4 is the AC capacitor fling-cut switch circuit of the present invention that critical piece is formed by diode D, auxiliary relay J2, magnetic latching relay J1 and single-chip microcomputer and peripheral circuit.The power supply of single-chip microcomputer is provided by the capacitance decompression rectifier power source, and 4 pin of single-chip microcomputer are measured the zero crossing of grid ac voltage, and 5 pin and 6 pin are controlled the closed and disconnected of auxiliary relay J2 and main relay J1 respectively chronologically, realizes that capacitor is thrown as and moves back throwing.AC capacitor fling-cut switch circuit of the present invention has the advantages that volume is little, do not have heater element, and whole switch can be fitted together with AC capacitor, makes the AC capacitor that has fling-cut switch, and is easy to install and use greatly.

AC capacitor fling-cut switch circuit of the present invention also can be applicable to the switching of the above high-voltage alternating capacitor of thousands of volts; the series connection that only needs the diode D in the contact protection circuit to be changed into several diodes gets final product; even ten diode series connection; the voltage that bear the contact when the closing of contact also only is 7V; AC capacitor fling-cut switch circuit of the present invention can cooperate vacuum contactor to use; the protection of contact protection circuit when working, vacuum contactor is arranged; can alleviate contacting greatly and the load when disconnecting, thereby prolong the useful life of vacuum contactor greatly.

The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention.

AC capacitor fling-cut switch circuit of the present invention is that discharge process by discharge loop is by the automatic conducting of diode; and during diode current flow, finish the closed and disconnected process of relay contact; diode has played the effect of protection mechanical contact in the process of the closing of contact and disconnection, thereby has circuit characteristics ingenious, simple and that control easily.Because AC capacitor fling-cut switch circuit of the present invention do not use controllable silicon as electronic switch, thereby avoided the AC capacitor that causes because huge the shove controllable silicon that causes and the damage of capacitor of moment because controllable silicon misleads.And in the switching process, do not produce surge current in the process of diode current flow yet, this point be in combination switch or the TSC switching scheme during controllable silicon conducting do not accomplish.

The switching of capacitor is the process that switch inserts capacitor or disconnect from electrical network as load, and AC capacitor fling-cut switch of the present invention can be used for resistive or inductive load switch equally.Switch with mechanical contact is used and the electrical equipment control field widely, uses single-chip microcomputer to control the closed and disconnected of mechanical contact accurately, and the co-operating contact protective circuit, and this will be a revolution of switch with mechanical contact.

Claims

1. an AC capacitor fling-cut switch circuit is made up of main relay contacts protective circuit, main relay and single chip control module and is it is characterized in that: the main relay contacts protective circuit is composed in series by diode and auxiliary relay contact, is connected in parallel on the main relay contacts two ends; The contact of main relay with by the AC capacitor series connection of switching at the electrical network two ends; The time sequencing of the closed and disconnected of single chip control module control main relay and auxiliary relay.

2. AC capacitor fling-cut switch circuit as claimed in claim 1 is characterized in that relay contact protection circuit can be the series connection of diode and electronic switch.Electronic switch can be controllable silicon, power MOS pipe, IGBT, high-voltage power triode etc.

3. AC capacitor fling-cut switch circuit as claimed in claim 1 is characterized in that single chip control module powered by the capacitance decompression rectification filtering power.