CN109728711B - Contactor electricity saver circuit and control method thereof - Google Patents
Contactor electricity saver circuit and control method thereof Download PDFInfo
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- CN109728711B CN109728711B CN201811585897.3A CN201811585897A CN109728711B CN 109728711 B CN109728711 B CN 109728711B CN 201811585897 A CN201811585897 A CN 201811585897A CN 109728711 B CN109728711 B CN 109728711B
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Abstract
The invention discloses a contactor electricity-saving appliance circuit and a control method thereof, wherein the contactor electricity-saving appliance comprises: the device comprises a contactor, a freewheeling diode D, a resonant inductor Lr and an N-MOS switching tube Q; the connection point of the cathode of the diode D and one end of the contactor is used for connecting the bus Vin, and the anode of the diode D1 and one end of the resonant inductor Lr are connected to the other end of the contactor together; the other end of the resonant inductor Lr is connected with the drain electrode of the N-MOS switching tube Q, and the source electrode of the N-MOS switching tube Q is grounded. The invention adopts the interaction of the resonance inductor Lr and the turn-to-turn capacitor CL in the contactor or the parasitic capacitor Cr of the N-MOS switching tube Q, so that the current of the N-MOS switching tube lags behind the change of voltage, thereby obtaining the effect of zero current switching-on and greatly reducing the loss of the electricity saver.
Description
Technical Field
The invention relates to a contactor, in particular to a topological circuit of a low-loss electricity saver.
Background
The circuit model of the contactor is shown in fig. 1, a contactor coil inductor L and a contactor internal resistance RL are connected in series to form a two-terminal network, and an inter-turn capacitor CL is connected in parallel with the two-terminal network. The circuit model of the conventional contactor electricity saver is shown in fig. 2 and comprises a contactor, a freewheeling diode D and an MOS transistor Q. When the MOS tube Q is switched on and is in an excitation stage, the excitation voltage Vin and the inductance current IL are increased; after the MOS tube Q is turned off, the inductive current is reduced under the internal resistance voltage drop of the contactor and the voltage drop of the freewheeling diode D, the degaussing stage is performed, the degaussing voltage is IL RL + VF, the inductor is balanced every period volt-seconds, Vin T D (1-T) D (IL RL + VF), wherein the inductive current of the IL coil is reduced, the turn-on voltage drop of the VF freewheeling diode is reduced, the T switching period is shortened, and the D duty ratio is increased. The conclusion that the coil current can be controlled by controlling the duty ratio can be easily obtained through a volt-second balance formula.
The circuit of fig. 2 is controlled by inputting a control signal to the GATE of the MOS transistor Q through the GATE pin of the control chip, and the MOS transistor Q needs to be turned on and off at a high frequency in the process of controlling the circuit current. Fig. 3 shows waveforms of drain-source voltage VDS, drain current IDS, coil current IL, coil voltage UL, and inter-hybrid capacitance current ICL of the MOS transistor of fig. 2, where in each switching process, overlap occurs in which VDS voltage decreases and IL current increases, and this loss is a necessary process for normal node state transition. However, when the voltage of the MOS transistor VDS is reduced in the turn-on process, the voltage on the inter-turn capacitor CL changes suddenly, a large current is generated instantaneously on the capacitor CL, and the instantaneous current is much larger than the normal working current of the contactor, and the current cannot be eliminated in the working process, so that the large turn-on loss is increased by being superposed on the normal inductive current. The higher the input voltage, the larger the loss is, but the switching loss caused by the turn-to-turn capacitance is not a necessary condition for the state transition of the circuit, but the loss of the circuit is increased to cause the increase of the system heating.
The most basic circuit shown in fig. 2 is adopted in the existing contactor power saver, and as can be seen from the above analysis, the circuit has defects, especially for high voltage, according to a capacitance characteristic formula:
the larger the voltage mutation on the turn-to-turn capacitor of the contactor is, the larger the generated capacitance current is, the larger the capacitance current is, the current appears at the moment that the VDS voltage of the MOS tube is close to the input voltage, so that the large current and the high voltage appear on the MOS tube at the same time, the loss of the MOS tube in the opening process is increased, and the integral loss of the electricity saver is increased while the MOS tube generates heat seriously.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to provide a circuit of the power saver of the contactor, which can greatly reduce the loss of the power saver of the contactor.
The technical scheme for solving the technical problems is as follows:
a contactor electricity-saving appliance circuit is characterized by comprising: the device comprises a contactor, a freewheeling diode D, a resonant inductor Lr and an N-MOS switching tube Q; the connection point of the cathode of the freewheeling diode D and one end of the contactor is used for connecting the bus Vin, and the anode of the freewheeling diode D1 and one end of the resonant inductor Lr are connected to the other end of the contactor together; the other end of the resonant inductor Lr is connected with the drain electrode of the N-MOS switching tube Q, and the source electrode of the N-MOS switching tube Q is grounded.
The technical scheme is that the resonance inductor Lr resonates with the turn-to-turn capacitor of the contactor or the drain-source parasitic capacitor of the N-MOS switching tube Q.
As a first alternative of the above technical means, the method further includes: and the capacitor is connected in parallel with two ends of the contactor. The alternative scheme realizes the aim of the invention by the resonance of the capacitor and the resonant inductor Lr.
As a second alternative of the above technical means, the method further includes: and the capacitor is connected between the drain electrode and the source electrode of the N-MOS switching tube Q in parallel. The alternative scheme also achieves the aim by means of resonance of the capacitor and the resonant inductor Lr.
Correspondingly, the invention also provides a first control method of the contactor electricity saver circuit, which is characterized in that: after the drain-source voltage of the N-MOS switch tube is reduced, the current flows through the N-MOS switch tube Q. The control method can realize the resonance of the resonance inductor Lr and the turn-to-turn capacitor CL of the contactor in the turn-on process of the N-MOS switching tube Q, so that the current in the turn-to-turn capacitor CL is not completely overlapped with the voltage at the drain end of the N-MOS switching tube Q.
Preferably, the N-MOS switch tube Q is not turned on until the drain-source voltage of the N-MOS switch tube is reduced to 0V. The current in the inter-turn capacitor CL and the voltage at the drain end of the N-MOS switching tube Q can be completely prevented from being overlapped.
Further, the driving speed of the MOS switch Q exceeds the rising speed of the resonant current.
Correspondingly, the invention also provides a second control method of the contactor electricity saver circuit, which is characterized in that: the N-MOS switch tube Q is switched on when the current in the resonant inductor Lr is reversed. The control method can realize that the resonant inductor Lr and the drain-source end parasitic capacitor Cr of the N-MOS switch tube Q form a resonant soft switch circuit.
The working principle of the invention is analyzed and explained by combining with the specific embodiment, and the invention has the advantages of greatly reducing the loss of the power saver and having obvious effect under wide-range input voltage. The circuit is simple and the cost is low.
Drawings
FIG. 1 is a contactor circuit model;
FIG. 2 is a main power circuit of a power saver of a conventional contactor;
FIG. 3 is a timing diagram illustrating the operation of the circuit of FIG. 2;
fig. 4 is a circuit diagram of the contactor power saver of the present invention, which is also a circuit diagram of the contactor power saver of the first embodiment;
FIG. 5 is a timing diagram illustrating the operation of the circuit according to the first embodiment of the present invention;
fig. 6 is a circuit of a contactor power saver according to a second embodiment of the present invention;
fig. 7 is a timing diagram illustrating the operation of the power saver of the contactor according to the second embodiment of the present invention.
Detailed Description
In order to make the invention more clearly understood, the invention is further described in detail below with reference to the attached drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
First embodiment
Referring to fig. 4, which is a schematic diagram of a contactor power saver circuit according to a first embodiment of the present invention, the contactor power saver circuit of this embodiment is composed of a contactor (equivalent to a contactor coil inductor L, a contactor coil turn-to-turn capacitor CL, and a contactor coil internal resistance RL), a freewheeling diode D, N-MOS switch tube Q, and a resonant inductor Lr, a connection point between a cathode of a diode D and one end of the contactor is used to connect a bus Vin, and an anode of a diode D1 and one end of the resonant inductor Lr are connected to the other end of the contactor together; the other end of the resonant inductor Lr is connected with the drain electrode of the N-MOS switching tube Q, and the source electrode of the N-MOS switching tube Q is grounded.
The control strategy adopted by the embodiment is as follows: and the N-MOS switch tube Q is switched on after the drain-source voltage of the N-MOS switch tube is reduced to 0V. The working principle is as follows:
when the switching-on process of the N-MOS switching tube Q is under an inductive load, because of the characteristic that the inductive current can not be suddenly changed, the working period of the whole system is run through, in the switching-on process of the N-MOS switching tube Q, firstly, the current IL of the coil inductor L is transferred into the MOS tube Q from the diode D, then, the drain-source voltage of the N-MOS switching tube is reduced, and in the reducing process of the drain-source voltage of the N-MOS switching tube Q, the following steps can be easily obtained: VL-VCL-Vin-VDS. The voltage of the inter-turn capacitor CL is suddenly changed, and the sudden change of the voltage of the inter-turn capacitor CL can enable the inter-turn capacitor CL to generate a large peak current to flow through the N-MOS switch tube Q, so that the N-MOS switch tube Q generates a large turn-on loss. In order to reduce the loss of the N-MOS switching tube Q caused by the turn-to-turn capacitor CL, a resonant inductor Lr is connected in series between the N-MOS switching tube Q and the turn-to-turn capacitor CL, the speed of current generation of the turn-to-turn capacitor CL is reduced, and the drain-source current IDS of the N-MOS switching tube begins to increase after the drain-source voltage VDS of the N-MOS switching tube is reduced to 0V.
The working process waveform of the embodiment is shown in fig. 3, and the embodiment can achieve the following beneficial effects:
when the N-MOS switch tube Q is switched on, the turn-to-turn capacitor CL and the resonance inductor Lr in the contactor interact to enable the current flowing through the N-MOS switch tube to appear after the drain-source voltage of the N-MOS switch tube is reduced to 0V, namely the current of the N-MOS switch tube lags behind the change of the voltage, so that the effect of zero current switching-on is obtained, and the loss of the power saver is greatly reduced.
When the N-MOS switching tube Q is switched off, zero-voltage switching-off can be realized due to the existence of the turn-to-turn capacitor CL, and at the moment of switching-off, a follow-current loop of current IL of a contactor coil inductor L is transferred to the turn-to-turn capacitor CL, so that the condition of zero-voltage switching-off of the N-MOS switching tube is met, the N-MOS switching tube Q has no loss, and the specific analysis is as follows:
at the moment of turning off the N-MOS switching tube, the current of the coil of the contactor needs a follow current loop, and at the moment, two paths are provided, namely L → RL → D and L → RL → CL. When the L → RL → D loop is turned on, the anode voltage of the diode D must reach the voltage VIN + VF, before that, the current path is the L → RL → CL loop, and the IL current charges the capacitor CL until the voltage at the two ends of the CL equals to VIN + VF, the L → RL → D loop is taken. In the process that current is transferred from the turn-to-turn capacitor CL follow current loop to the diode D follow current loop, the voltage of the turn-to-turn capacitor CL starts to rise from 0V, at the moment, the N-MOS switching tube Q is already in a closed state, and the turn-off loss is greatly reduced. Therefore, the embodiment can realize zero-voltage turn-off in the turn-off process, and the turn-off loss is low.
The driving speed of the MOS switch tube Q exceeds the resonant current rising speed of the turn-to-turn capacitor CL and the resonant inductor Lr of the contactor, so that the turn-to-turn capacitor CL has large current to appear on the MOS switch tube Q after the drain-source voltage of the MOS switch tube Q is reduced, and the loss is reduced.
The effects of the present invention will be described below with reference to actual test data. In the range of 250Vac to 500Vac, the actual system losses are significantly reduced, as shown in table 1 below:
TABLE 1 Power consumption at different input voltages
| Input voltage | FIG. 2 Power consumption before improvement (W) | FIG. 4 improved Power consumption (W) of the invention |
| 250Vac | 1.45 | 0.55 |
| 300Vac | 2.06 | 0.75 |
| 400Vac | 3.48 | 1.19 |
| 500Vac | 5.30 | 1.79 |
It should be noted that, for this embodiment, the turn-to-turn capacitor CL and the resonant inductor Lr are used for resonance, and if a capacitor is connected in parallel to two ends of the contactor to replace the turn-to-turn capacitor CL, the object of the present invention can also be achieved by using the parallel capacitor and the resonant inductor Lr for resonance.
Second embodiment
Referring to fig. 6, the present embodiment is different from the first embodiment in that the resonant relationship between the drain-source parasitic capacitance Cr of the N-MOS switch tube Q and the resonant inductor Lr is utilized, and the N-MOS switch tube Q is turned on when the current in the resonant inductor Lr is reversed, so that zero-voltage turn-on can be conveniently realized, and turn-on loss is reduced. The circuit turn-on process is analyzed below in conjunction with fig. 7.
The opening process: therefore, zero voltage switching-on can be realized, the current change is analyzed from the time t0 shown in fig. 7, after the MOS switching tube Q is switched off, the resonant inductor Lr and the coil inductor L jointly charge the parasitic capacitor Cr until the time t1 when the diode D is switched on, the parasitic capacitor Cr is charged by constant current, and the voltage U at the end of the parasitic capacitor Cr isCrRise, rising slope
After the diode D is conducted, the coil inductor L continues current through the diode D, the parasitic capacitor Cr, the resonant inductor Lr and the voltage of the bus Vin form a resonant circuit, in the resonant process, the resonant inductor Lr charges the parasitic capacitor Cr, and the voltage U at the end of the parasitic capacitor Cr isCrIncreasing, current I in coil inductance LLrContinuously decreases until t2 time, the current I in the coil inductance LLrDrop to zero, parasitic capacitance Cr terminal voltage UCrA resonance peak is reached. After time t2, the parasitic capacitance Cr discharges to the resonant inductor Lr, and the current I in the coil inductor LLrChange direction, parasitic capacitance Cr terminal voltage UCrContinuously decreases until t3 moment UCrWhen Vin is reached, the voltage across the resonant inductor Lr is zero, and the current I in the coil inductor L is zeroLrThe inverse resonance peak is reached. After the time t3, the resonant inductor Lr charges the parasitic capacitor Cr in the reverse direction, and the voltage U at the end of the parasitic capacitor Cr isCrContinues to descend until time U at t4Cr0. terminal voltage U of parasitic capacitance Cr after t4CrClamped by reverse current, the Q body diode of the MOS switch tube is conducted, the voltage at two ends of the resonant inductor Lr is Vin, and the current I in the coil inductor LLrLinearityDecrease until time t5, ILrWhen the voltage drop of the MOS switch Q is zero during the period t4 to t5, the MOS switch Q is turned on during this period, and zero-voltage turn-on is realized.
And (3) a turn-off process: due to the existence of the parasitic capacitance Cr, the voltage variation speed of the MOS switch transistor Q can be reduced, so that the loss of the MOS switch transistor Q is reduced, the working mechanisms of the MOS switch transistor Q and the MOS switch transistor Q in the turn-off process are the same as those in the first embodiment, and the principle of achieving the zero-voltage turn-off is not described herein again.
It should be noted that, for the present embodiment, the parasitic capacitance Cr resonates with the resonant inductor Lr, for example, a capacitor is connected in parallel to the drain and source of the MOS switch Q, and the parallel capacitor resonates with the resonant inductor Lr to replace the parasitic capacitance Cr, so that the object of the present invention can be achieved.
The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.
Claims (3)
1. A contactor electricity-saving appliance circuit is characterized by comprising: the device comprises a contactor, a freewheeling diode D, a resonant inductor Lr and an N-MOS switching tube Q; the connection point of the cathode of the freewheeling diode D and one end of the contactor is used for connecting the bus Vin, and the anode of the freewheeling diode D1 and one end of the resonant inductor Lr are connected to the other end of the contactor together; the other end of the resonant inductor Lr is connected with the drain electrode of the N-MOS switching tube Q, the source electrode of the N-MOS switching tube Q is grounded, and the driving speed of the MOS switching tube Q exceeds the rising speed of the resonant current.
2. The contactor power saver circuit of claim 1 further comprising: and the capacitor is connected in parallel with two ends of the contactor.
3. The contactor power saver circuit of claim 1 further comprising: and the capacitor is connected between the drain electrode and the source electrode of the N-MOS switching tube Q in parallel.
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| CN201811585897.3A CN109728711B (en) | 2018-12-24 | 2018-12-24 | Contactor electricity saver circuit and control method thereof |
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| CN201811585897.3A CN109728711B (en) | 2018-12-24 | 2018-12-24 | Contactor electricity saver circuit and control method thereof |
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| CN109728711B true CN109728711B (en) | 2020-09-15 |
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| CN110931312B (en) * | 2019-11-26 | 2022-05-20 | 广州金升阳科技有限公司 | Contactor power-saving control method and control circuit applying same |
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| CN107658181A (en) * | 2017-10-19 | 2018-02-02 | 深圳南云微电子有限公司 | A kind of contactor electricity-saving appliance |
| CN107834839A (en) * | 2017-10-19 | 2018-03-23 | 深圳南云微电子有限公司 | A kind of contactor electricity-saving appliance |
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Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5493437A (en) * | 1977-12-30 | 1979-07-24 | Matsushita Electric Works Ltd | Power saving relay circuit |
| CN103415905A (en) * | 2010-11-01 | 2013-11-27 | 力登美国股份有限公司 | Method and apparatus for improved relay control |
| CN103414340A (en) * | 2013-07-26 | 2013-11-27 | 北京交通大学 | Zero-current soft switching converter |
| CN203504408U (en) * | 2013-09-29 | 2014-03-26 | 美的集团股份有限公司 | Voltage-reduction anti-interference circuit and circuit board |
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| CN107834839A (en) * | 2017-10-19 | 2018-03-23 | 深圳南云微电子有限公司 | A kind of contactor electricity-saving appliance |
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