CN103474293B - Electronic type power-saving alternating current contactor - Google Patents

Abstract

The invention discloses an electronic power-saving AC contactor, which includes two parts: an additional electronic unit and a conventional AC contactor. Composed of a return spring and an excitation coil; the additional electronic unit is a four-port network with a first input port, a second input port, a first output port and a second output port; the first input port and the second input port are respectively connected to the AC The first end of the voltage is connected to the second end, and the first output port and the second output port are respectively connected to the first end and the second end of the exciting coil; the additional electronic unit is provided with a switch circuit and an energy storage circuit; the switch circuit One end of one end is connected to the first input port; the other end is connected to the first output port and one end of the energy storage circuit; the other end of the energy storage circuit is connected to the second output port and the second input port; wherein, the switch circuit is composed of a gas discharge tube, and the storage Power circuits are made up of capacitors.

Description

Electronic power-saving AC contactor

technical field

The invention relates to the field of low-voltage electrical appliances, in particular to an "electronic power-saving AC contactor" transformed from only two electronic devices.

Background technique

AC contactor is a low-voltage electrical appliance that is widely used. As of 2012, there are as many as 1 billion AC contactors running online in my country, and the number of AC contactors is increasing at a rate of 80 million per year. Its working principle is to use the electromagnet to drive the moving contact (moving contact) and the static contact (moving contact) to close or separate, so as to achieve the purpose of connecting or cutting off the circuit. It is suitable for starting or controlling three-phase induction motors and other electrical equipment.

Figure 1 is a working principle diagram of a traditional AC contactor. This traditional AC contactor is mainly composed of a moving iron core, a static iron core, an excitation coil, a return spring, a moving-break contact, and a moving-closing contact. When the excitation coil is connected to AC220V, AC110V or AC380V voltage (hereinafter referred to as AC220V, AC110V or AC380V as AC voltage or excitation power supply), the moving iron core is closed to the static iron core by the magnetic force generated by the excitation coil, and is connected to the moving iron core. The linked moving contact is also closed, and the external circuit is connected through the moving contact; when the AC voltage on the excitation coil is disconnected, the moving iron core loses its magnetism and is contacted with the static iron by the action of the return spring. The core is separated, the moving contact is reset and disconnected, and the external circuit is cut off.

To sum up, the working process of this traditional AC contactor can be divided into three stages: "pulling", "holding" and "resetting":

1. Pull-in: The excitation coil is connected to the AC voltage, and the moving and static iron cores are pulled together. At this stage, in order to overcome the inertia of the moving iron core and the elastic force of the return spring, the excitation power supply must provide a relatively large power (hereinafter referred to as the "pulling power"), so that the moving and static iron cores can attract each other, and, The greater the "pulling power", the more crisp and fast the suction;

2. Holding: The excitation coil continues to be connected to the AC voltage, and the moving and static iron cores continue to maintain the state of attraction. At this stage, the excitation power supply only needs to provide a small power (hereinafter referred to as "holding power"), and the moving and static iron cores can also continue to attract. If at this stage, the excitation power supply provides excessive holding power, it will cause waste of electric energy and lead to undue heating of the AC contactor;

3. Reset: The excitation coil is disconnected from the AC voltage, and the moving and static iron cores are "reset" separated.

AC contactors have different purposes and structures, but their working principles are the same as those shown in Figure 1.

The traditional AC contactor has the following serious disadvantages because the same AC voltage is passed through the excitation coil in the pull-in and hold stages:

1. Unnecessary power consumption: As mentioned above, in the pull-in and holding stages, the excitation coil of the traditional AC contactor is connected with the "same" AC voltage, which makes the holding power too large, resulting in unnecessary electric energy loss;

2. Heating: The evil result of unnecessary power loss is "heating and heating". In severe cases, it will even burn the excitation coil of the traditional AC contactor;

3. The advantages and disadvantages of the pull-in action are "depending on luck": at the moment when the excitation coil is connected to the AC voltage, when the instantaneous value of the AC voltage is high, the conventional AC contactor pulls in strongly; on the contrary, the excitation coil When the AC voltage is turned on, when the instantaneous value of the AC voltage is low, the conventional AC contactor will pull in bluntly. and burned;

4. Existence of annoying AC noise;

5. Low power factor.

Aiming at the serious shortcomings of traditional AC contactors, technicians in the electronics and electrical industry have researched and designed a variety of "power-saving circuits", "power savers", and "energy-saving AC contactors" to improve the performance of traditional AC contactors. device". Chinese patent application No. 97216246.1 for "High-efficiency and energy-saving AC contactor", application No. 94202133.9 for "Energy-saving AC contactor device", and application No. 201010144412.4 for "An energy-saving AC contactor" disclosed the respective research results of the patent applicants ; Institutions or manufacturers in Hangzhou, Changzhou, Zhuhai and other places also have "power savers" that are used to improve the performance of conventional AC contactors.

The above-mentioned prior art has indeed made useful explorations and achieved certain achievements in order to improve the performance of conventional AC contactors, but generally has the following defects:

1. The structure is complex and difficult to implement;

2. There are too many electronic devices used, and the electronic circuit is too complicated; the "AC contactor power saver" controlled by a single-chip microcomputer is susceptible to electromagnetic interference from the AC contactor itself or electrical appliances such as motors, resulting in internal program execution errors and "flying jumps". "Miscontrol - this miscontrol can lead to catastrophe on some occasions!

3. The price of the products produced is too high. For example, the price of the QXJB AC contactor power saver produced by a certain company in Zhuhai City, Guangdong Province is as high as 1,500 yuan per set! The price of a small AC contactor is only more than 20 yuan, and the price of a medium-sized AC contactor is only a few hundred yuan. Such an expensive "QXJB AC contactor power saver" will make very few users.

4. Due to the complex electronic circuit and many electronic devices used, it is difficult to integrate the power saving control part of the AC contactor with the AC contactor. Inconvenient, wiring trouble.

5. Due to the complex electronic circuit and many electronic devices used, the power consumption of the power-saving control part of the AC contactor (AC-DC conversion loss, IC power consumption, actuator power consumption, etc.) will increase. It is even so large that it is comparable to the holding power of a small contactor.

It is precisely because of the above defects in the existing technology that the following situation has emerged: "At present, there is a certain market for power-saving AC contactors in my country, but they are not popular enough. Traditional AC contactors currently dominate the use of users. The main reason is that the price of energy-saving contactors is relatively expensive, and users cannot accept the one-time investment. The country needs to increase policy efforts in the promotion of energy-saving contactors to promote the wide application of energy-saving contactors. (Reference 1: Qian Jinchuan et al. A Review of Energy-Saving Technology for AC Contactors. China Electronics Business. Issue 4, 2011)

Aiming at the status quo of the prior art, the goal of the present invention is: adhere to the tenets of "the essence must be simple, and only simple and practical can be passed on for a long time" and "there is no best, only better", "the application of electronic technology , to transform traditional industries", to design an "electronic power-saving AC contactor" that is as simple as possible, uses as few components as possible, is as cheap as possible, and has performance that exceeds the existing technology.

Contents of the invention

An electronic power-saving AC contactor, including two parts of an additional electronic unit and a conventional AC contactor, is characterized in that:

The conventional AC contactor is composed of a moving-break contact DD, a moving-closing contact DH, a moving iron core M, a static iron core G, a return spring F, and an excitation coil L;

The additional electronic unit is a four-port network, with four ports N1, N2, P1, and P2, ports N1, N2 are two input ports, P1, P2 are two output ports; input ports N1, N2 are respectively connected to terminals S1 and S2 of the AC voltage, and output ports P1 and P2 are respectively connected to terminals A1 and A2 of the excitation coil L;

The inside of the four-port network additional electronic unit is provided with a switch circuit and an energy storage circuit, and its connection mode is: one end of the switch circuit is connected to the N1 end, and the other end is connected to the P1 end. One end of the energy storage circuit is connected to the P1 end, the other end is connected to the P2 end, and the P2 end is connected to the N2 end; or: one end of the switch circuit is connected to the N2 end One end and the other end are connected to the P2 end, one end of the energy storage circuit is connected to the P1 end, the other end is connected to the P2 end, and the P1 end is connected to the N1 end;

The switch circuit is composed of a gas discharge tube GDT (gaseous discharge tube), and the energy storage circuit is composed of a capacitor C;

The two electronic devices of the gas discharge tube GDT and the capacitor C form the four-port additional electronic unit; its circuit structure and composition are as follows: the N1 terminal, the gas discharge tube GDT, the P1 terminal, the capacitor C, The P2 terminal and the N2 terminal are sequentially connected in series to form the four-port additional electronic unit; or: the N1 terminal, the P1 terminal, the capacitor C, the P2 terminal, the gas discharge tube GDT and the N2 terminal are sequentially connected in series to form a said four-port additional electronic unit;

The gas discharge tube GDT can be any one of a semiconductor discharge tube (thyristor surgesuppressors), an electrostatic suppressor (Electro-Static discharge), a transient voltage suppressor (Transient Voltage Suppressor) or a piezoresistor (pressure sensitiveresistor). Such as semiconductor discharge tube replacement;

The above-mentioned additional electronic unit is combined with the conventional AC contactor in the above-mentioned manner to form a new type of "electronic power-saving AC contactor".

The additional electronic unit has the function of automatically identifying randomly connected AC voltages: when the instantaneous value of the AC voltage is less than the threshold voltage, the electronic power-saving AC contactor does not pull in; otherwise, when the instantaneous value of the AC voltage is greater than When the threshold voltage and the pull-in power provided by it are large enough, the electronic power-saving AC contactor will pull in strongly.

When the voltage across the switch circuit is greater than the threshold voltage, it is turned on;

When the switch circuit is turned on, the energy storage circuit charges and stores energy.

Apply the present invention, can obtain following beneficial effect:

1. Inexpensive: The "additional electronic unit" used to improve the performance of conventional AC contactors in this invention has only two electronic devices, and the total cost is less than 0.3 yuan. For only a few cents, the conventional AC contactor can be upgraded to an "electronic power-saving AC contactor" with excellent performance, which solves the problem revealed in Reference 1: "At present, there are already certain power-saving AC contactors in our country. market, but it is not popular enough. Traditional AC contactors currently dominate the use of users. The main reason is that the price of power-saving contactors is relatively expensive, and users cannot accept the one-time investment. Intensify the policy on the promotion of contactors and promote the wide application of energy-saving contactors", creating conditions for the large-scale promotion of energy-saving AC contactors;

2. Wumart: The above two electronic devices are small in size, and they can be integrated into the inside of a conventional AC contactor to manufacture an integrated, pleasing-looking electronic power-saving AC contactor. This point is far beyond the reach of existing technologies and is difficult to achieve;

3. Reliability: The reliability of electronic products is inversely proportional to the number of electronic devices used, and the price is directly proportional to the number of electronic devices used. The more electronic components used and the more complex the electronic circuit, the lower the reliability and the higher the price. The present invention only uses two electronic devices, and both of them are power devices for strong electricity and are not afraid of electromagnetic interference. Therefore, not only the cost is low, but also the reliability is extremely high;

4. Life extension: a traditional CJX2-2510 AC contactor and a CJX2-2510 AC contactor of the same type transformed with the "additional electronic unit" of the present invention, run simultaneously for 10 hours at the same place with a room temperature of 34°C Finally, the surface temperature of the former has exceeded 60°C, which is hot to touch; the surface temperature of the latter is still at room temperature. Temperature rise is the enemy of electronic and electrical products. The higher the temperature rise, the shorter the service life of the product. On the contrary, the service life can be extended. Therefore, the present invention has the function of "prolonging life" to prolong the service life of the product;

5. Fast: The present invention has a "threshold voltage". When the AC voltage is greater than the "threshold voltage" and the "pull-in power" is large enough, the AC contactor will do the pull-in action. Therefore, the present invention has strong suction action, crisp sound and fast suction speed. The invention has the advantages of quick pull-in, can reduce the electric arc of the contact, prevent the burn failure of the contact, and play an important role in protecting the contact and prolonging the service life of the contactor.

6. Power saving: low temperature rise is an intuitive manifestation of power saving, and the actual measurement results also show that the present invention has high power saving efficiency.

In order to actually test the power-saving efficiency of the present invention, a prototype was made (only two electronic devices are needed, and the prototype is easy to make), and the "EPM8200 multifunctional electrical parameter measuring instrument" was used to measure the following two AC contactor indicators:

(1) The CJX2-2510 conventional AC contactor without the "additional electronic unit" of the present invention (hereinafter referred to as the conventional part);

(2) According to the method of the present invention, the CJX2-2510 conventional AC contactor is transformed into a new type of "electronic power-saving AC contactor" (hereinafter referred to as the new type) after adding an "additional electronic unit". pieces).

The results are shown in Table 1 below:

Table 1

The above measured results show that the "active power saving rate" of the present invention reaches 67%, and the "apparent power saving rate" reaches 83%.

7. Noise suppression. Since the birth of the world's first AC contactor in 1924, AC noise and AC contactors have "followed each other like a shadow", and the AC noise of conventional AC contactors has reached the point where people in the industry are "common and not surprising". The present invention can be quiet and noiseless, and even in the dead of night, no noise can be heard, which really amazes viewers in the industry.

8. Increase PF. As mentioned above, the measured results show that the power factor (PF) of the conventional AC contactor is only 0.332, but after the application of the present invention, the PF rises to 0.655.

Description of drawings

Figure 1 is a schematic diagram of a conventional AC contactor;

Fig. 2 is the principle block diagram of embodiment 1;

Fig. 3 is the schematic circuit diagram of embodiment 1;

Figure 4 is an AC voltage waveform;

Fig. 5 is the schematic diagram of the work of embodiment 1 in the t2～t3 time domain:

Fig. 6 is the schematic diagram of the work of embodiment 1 when t=th:

Fig. 7 is the working schematic diagram when t=t3 of embodiment 1:

Fig. 8 is the working schematic diagram of embodiment 1 in t3～t4 time domain:

Fig. 9 is the schematic diagram of the work of embodiment 1 in the transition zone:

Fig. 10 is the schematic diagram of the work of embodiment 1 in the t5～t6 time domain:

Fig. 11 is the schematic diagram of the work of embodiment 1 when t=t6:

Fig. 12 is the schematic diagram of the work in the t6-t7 time domain of embodiment 1;

Fig. 13 is the principle block diagram of embodiment 2:

Fig. 14 is the schematic circuit diagram of embodiment 2;

Fig. 15 is the schematic circuit diagram of embodiment 3;

FIG. 16 is a schematic circuit diagram of Embodiment 4.

Detailed ways

Below in conjunction with accompanying drawing, illustrate the embodiment of the present invention.

Fig. 2 is a schematic block diagram of Embodiment 1 of the present invention, and Fig. 3 is a schematic circuit diagram of Embodiment 1. In Fig. 2 and Fig. 3: L is the excitation coil in the conventional AC contactor, and A1 and A2 are its two connection ports; the dotted line box 100 represents the additional electronic unit of the present invention, which has two input ends, namely N1 A four-port network with N2 terminal and two output terminals, ie, P1 and P2 terminals; 101 in the additional electronic unit 100 is a switch circuit, and 102 is an energy storage circuit.

Combining Figure 2 and Figure 3; an electronic power-saving AC contactor, including two parts of an additional electronic unit 100 and a conventional AC contactor, is characterized in that:

The conventional AC contactor is composed of a moving-break contact DD, a moving-closing contact DH, a moving iron core M, a static iron core G, a return spring F, and an excitation coil L;

The additional electronic unit 100 is a four-port network, with four ports N1, N2, P1, and P2, ports N1, N2 are two input ports, P1, P2 are two output ports; input ports N1, N2 is respectively connected to terminals S1 and S2 of the AC voltage, and output ports P1 and P2 are respectively connected to terminals A1 and A2 of the excitation coil L;

The four-port network additional electronic unit 100 is internally provided with a switch circuit 101 and an energy storage circuit 102, and its connection mode is: one end of the switch circuit 101 is connected to the N1 end, and the other end is connected to the P1 end. end, one end of the energy storage circuit 102 is connected to the P1 end, the other end is connected to the P2 end, and the P2 end is connected to the N2 end;

The switch circuit 101 is composed of a gas discharge tube GDT, and the energy storage circuit 102 is composed of a capacitor C;

The two electronic devices of the gas discharge tube GDT and the capacitor C form the four-port additional electronic unit 100;

The circuit structure and composition of the four-port additional electronic unit 100 are as follows: the N1 terminal, the gas discharge tube GDT, the P1 terminal, the capacitor C, the P2 terminal, and the N2 terminal are sequentially connected in series to form the four-port Additional electronics unit 100 .

The above-mentioned additional electronic unit 100 is combined with the conventional AC contactor in the above-mentioned manner to form a new type of "electronic power-saving AC contactor".

Combined with Figure 4: the mathematical expression of the AC voltage input from S1 and S2 is:

u=Umsin（2πft＋φ）

In the above formula: u is the instantaneous value of the AC voltage, Um is the amplitude value of the AC voltage, f is the frequency of the AC voltage, and φ is the initial phase angle of the AC voltage.

For the sake of simplicity, it is assumed that the initial phase angle φ=0, then the expression of the instantaneous value u of the AC voltage is:

u=Umsin2πft

Its waveform is shown in Figure 4. In the figure: t represents time, u represents the instantaneous value of AC voltage.

The working principle of the gas discharge tube GDT is: when the voltage UT at both ends of the gas discharge tube is lower than its discharge voltage Usdc (hereinafter referred to as the discharge voltage Usdc as the switching circuit threshold voltage referred to as "threshold voltage"), the gas discharge tube GDT is a The insulator presents a high impedance and is approximately an open circuit, that is, the gas discharge tube GDT is in a cut-off state; when the voltage UT at both ends of the gas discharge tube is greater than its discharge voltage Usdc, an arc discharge is generated and presents a low impedance, which is approximately a short circuit, that is, the The gas discharge tube GDT mentioned above is in the conduction state. According to the above working principle of the gas discharge tube GDT, the AC voltage in Figure 4 is divided into the following regions:

1. The area where the power-on refuses to pull in is the shaded area in Figure 4. In this area, the instantaneous value of AC voltage u=Umsin2πft is less than the discharge voltage Usdc of the gas discharge tube GDT, namely:

u=Umsin2πft＜Usdc

The gas discharge tube GDT is in an off state. If the AC voltage is switched on in this area, the electronic power-saving AC contactor will refuse to pull in.

2. The energy storage area, that is, the Q1 and Q2 areas in Fig. 4, in this area, UT>Usdc, the gas discharge tube GDT is in the conduction state, and the capacitor C and the exciting coil L are both charged and stored.

3. The energy release area, that is, the t3-t4, t6-t7 area in Figure 4, in this area, UT<Usdc, the gas discharge tube GDT is in the cut-off state, and the capacitor C and the exciting coil L are complementary to discharge and release energy.

4. The transition area, that is, the area t4-t5 in Figure 4, this area is a very special area, which will be described in detail below.

Elaborate the working process of present embodiment 1 below in conjunction with accompanying drawing:

When t=t1 (t=t1 is in the aforementioned "power-on rejection area"), the AC voltage is turned on. At this time, since the discharge of the capacitor C and the excitation coil L has ended before the AC voltage is turned on, the capacitor C The voltage at both ends (that is, the output voltage of the additional electronic unit 100 ) UC=0; at this moment t=t1, the instantaneous value of the AC voltage:

u1=Umsin2πft1<Usdc

That is, the voltage UT at both ends of the gas discharge tube GDT is less than its discharge voltage Usdc, so it is in a cut-off state, the output voltage UC of the additional electronic unit 100=0, and the electronic power-saving AC contactor does not pull in.

Combining with Figure 1, it should be clear to those skilled in the art that if the instantaneous value u1=Umsin2πft1 of the AC voltage at time t=t1 is directly applied to the excitation coil L of a conventional AC contactor, one of the following adverse phenomena may occur:

1. The value of u1 is too low, the magnetic force generated by it is smaller than the elastic force of the return spring F, and the conventional AC contactor consumes power in vain and does not pull in;

2. The value of u1 is not large enough, and the magnetic force generated by it is only slightly greater than the elastic force of the return spring F. Conventional AC contactors pull in reluctantly and bluntly, and their contacts are easily burned due to the long ignition time.

The above phenomenon is one of the disadvantages of conventional AC contactors.

Combined with Figure 3 and Figure 4: when t=t2, the instantaneous value of AC voltage:

u2=Umsin2πft2>Usdc

The gas discharge tube GDT is discharged and turned on, which is approximately a short circuit. Combined with Fig. 3, Fig. 4, and Fig. 5, since the gas discharge tube GDT is discharged and turned on, the charging current i23 provided by the AC voltage, the present invention enters the above-mentioned "energy storage area", and the capacitor C and the exciting coil L Obtain the charging current of ic23 and iL23 respectively.

Combined with Figure 4 and Figure 6, when t=th, the charging current provided by the AC voltage is Ih, and the capacitor C and the excitation coil L obtain the charging currents of Ich and ILh respectively.

The output voltage of the additional electronic unit 100, that is, the voltage across the capacitor C or the excitation coil L is sufficiently high, that is:

Uch≈uh=Umsin2πfth

In the above formula, Uch represents the output voltage of the additional electronic unit 100 at t=th, and uh represents the instantaneous value of the AC voltage at t=th.

When t=th, the AC voltage has driven the excitation coil L to obtain a sufficiently strong charging current, that is, the excitation current ILh. The AC contactor is then strongly sucked and enters the holding state.

From the analysis so far, it can be concluded that the additional electronic unit 100 has the function of automatically identifying randomly connected AC voltages: when the instantaneous value of the AC voltage u=Umsin2πft<Usdc (that is, the threshold voltage), the gas discharge tube GDT is cut off, and the When the voltage UC=0 output by the additional electronic unit 100 described above, the electronic power-saving AC contactor does not pull in; when the instantaneous value of AC voltage u=Umsin2πft>Usdc, the gas discharge tube GDT discharges and conducts, and the suction provided by the AC voltage When the closing power is large enough, the electronic power-saving AC contactor will pull in strongly.

In short: the additional electronic unit 100 has the function of automatically identifying randomly connected AC voltages: when the instantaneous value of the AC voltage is less than the threshold voltage, the electronic power-saving AC contactor does not pull in; otherwise, when the instantaneous value of the AC voltage When the value is greater than the threshold voltage Usdc and the pull-in power provided by it is large enough, the electronic power-saving AC contactor will pull in strongly.

Therefore, as long as you choose a gas discharge tube with a sufficiently high Usdc, you can ensure that the electronic power-saving AC contactor has a strong suction.

There is a threshold voltage to ensure that the electronic power-saving AC contactor has a strong pull-in, a crisp sound and a fast pull-in speed. The feature of rapid suction of the present invention can reduce the arcing of the contacts, prevent the burnout of the contacts, and play an important role in protecting the contacts and prolonging the life of the AC contactor, which is an important function of the present invention and an obvious advantage of the present invention. one.

Combined with Figure 4 and Figure 7, when t=t3, the AC voltage is in the positive half cycle when the S1 terminal is at a high level and the S2 terminal is at a low level, that is, the S1 terminal is a positive terminal and the S2 terminal is a negative terminal, and its instantaneous value is u3=Umsin2πft3; at this time, the voltage across the capacitor C has been charged to UC3, and the voltage UT across the gas discharge tube GDT is:

UT＝u3－UC3＝Umsin2πft3－UC3＜Usdc

The gas discharge tube GDT is turned off due to UT<Usdc, and the present invention enters the above-mentioned "energy release region".

Combined with Figure 4 and Figure 8, in the time domain from t3 to t4, that is, in the "energy release region" mentioned above:

Since the gas discharge tube GDT has been turned off, it is equivalent to that the additional electronic unit 100 has been disconnected from the AC voltage;

Before the AC voltage is disconnected, both the capacitor C and the excitation coil L store electric energy;

In this time domain from t3 to t4, the capacitor C discharges and releases energy, and its discharge current is ic34; because the current on the excitation coil L cannot change abruptly, it takes the current as iL34 "freewheeling"; the discharge current of capacitor C ic34, excitation The freewheeling current iL34 of the coil L is equal in value and complementary in direction, and the electronic power-saving AC contactor continues to maintain the holding state based on the complementary discharge of the capacitor C and the excitation coil L.

In other words: in the time domain when the gas discharge tube GDT is turned off, the electronic power-saving AC contactor relies on the electric energy stored in the capacitor C and the excitation coil L to maintain the holding state.

Combined with Figure 4 and Figure 9, when t=t4:

The AC voltage is in the negative half cycle when the S2 terminal is high level and the S1 terminal is low level, that is, the S2 terminal is the positive terminal and the S1 terminal is the negative terminal, and its instantaneous value is u4=Umsin2πft4;

As mentioned above, in the time domain from t3 to t4 before t=t4, the capacitor C discharges the excitation coil L. When the discharge reaches t=t4, since the voltage on the capacitor cannot change suddenly, the capacitor C remains at the P1 terminal as Positive and P2 terminals are negative voltage Uc4 (here, the voltage Uc4 is called "residual voltage");

At this time, the voltage UT across the gas discharge tube GDT is:

UT＝Uc4＋u4＝Uc4＋Umsin2πft4＞Usdc

The gas discharge tube GDT discharges and conducts, and the AC voltage charges the capacitor C again, and the charging current is ic45a; the present invention enters the above-mentioned "transition region".

So far, combined with Figure 4, it should also be emphasized that at the "zero-crossing point" when the AC voltage transitions from the positive half cycle to the negative half cycle, that is, the point t=t10 in the time domain of t3~t4, the AC voltage is zero, but the capacitor C still exists at the P1 terminal Positive, P2 terminal is negative voltage.

When approaching the time t=t4, the freewheeling current of the excitation coil L is iL45. Since the current on the inductor cannot change suddenly, after the time t=t4, it still continues to flow in the original direction. According to the polarity of the AC voltage at this time, the charging current i45 output by the AC voltage cannot provide this freewheeling current iL45, and at this time the residual voltage Uc4 on the capacitor C can just provide the above-mentioned freewheeling current iL45, so the residual voltage on the capacitor C Uc4 does not pass through the path of GDT-N1-S1-S2, that is, it does not discharge through AC voltage (if so, the power factor will drop) but passes through the path of P1-L-P2, and the discharge current ic45b=iL45 is complementary to the excitation coil L Discharge, so that the magnetic coil L maintains "freewheeling". This is an important reason why the power factor of the present invention is much higher than that of conventional AC contactors. High power factor is an important function of the present invention and also one of the obvious advantages of the present invention.

When t=t5, the "freewheeling" current iL45 of the excitation coil L gradually drops to zero, and the present invention enters the state shown in Figure 10: the charging current i56 provided by the AC voltage, the capacitor C and the excitation coil L respectively obtain ic56, The charging current of iL56.

Combined with Figure 4 and Figure 11, when t=t6, the AC voltage is in the negative half cycle when the S1 terminal is low and the S2 terminal is high, that is, the S1 terminal is the negative terminal and the S2 terminal is the positive terminal, and its instantaneous value is u6 =Umsin2πft6; at this time, the voltage across the capacitor C has been charged to UC6, and the voltage UT across the gas discharge tube GDT is:

UT＝u6－UC6＝Umsin2πft6－UC6＜Usdc

The gas discharge tube GDT is turned off because UT<Usdc, and the present invention enters the above-mentioned "energy release region" again.

Combined with Fig. 4 and Fig. 12, in the time domain from t6 to t7, that is, in the "energy release region": since the gas discharge tube GDT has been turned off, it is equivalent to disconnecting the additional electronic unit 100 from the AC voltage;

Before the AC voltage is disconnected, both the capacitor C and the excitation coil L store electric energy;

Capacitor C discharges and releases energy, and its discharge current is ic67; because the current on the excitation coil L cannot be mutated, it takes the current as iL67 "freewheeling"; the discharge current ic67 of capacitor C and the freewheeling current iL67 of excitation coil L are both The values are equal and the directions are complementary. The electronic power-saving AC contactor will continue to maintain the holding state based on the complementary discharge of the capacitor C and the excitation coil L.

So far, combined with Figure 4 and Figure 12, it should also be emphasized that at the "zero crossing point" when the AC voltage transitions from the negative half cycle to the positive half cycle, that is, the point t=t20 in the time domain from t6 to t7, the AC voltage is zero, but the capacitance C is still Store P1 terminal as negative and P2 terminal as positive voltage.

When t=t7, the voltage UT across the gas discharge tube GDT is greater than its threshold voltage Usdc, and it breaks down and conducts again, and the capacitor C and the excitation coil L enter the state of charging and storing energy again. Such a repeated cycle can ensure that the electronic power-saving AC contactor maintains a stable holding state.

Set forth so far, can summarize the following technical characteristics of the present invention:

1. When the voltage at both ends of the switch circuit is greater than the threshold voltage, it is turned on;

2. When the switch circuit is turned on, the energy storage circuit charges and stores energy.

Comparative analysis of this embodiment and conventional AC contactors:

1. Suction

In this embodiment, the gas discharge tube GDT with a suitable threshold voltage Usdc is selected. When the voltage on the capacitor C is high enough and the magnetic force generated by the excitation coil L is strong enough to forcefully and quickly attract the moving iron core, this embodiment Only strong suction.

As mentioned above, this function of this embodiment is extremely important, and it is well known to people in the industry that the quicker and quicker the moving iron core pulls in, the shorter the time for the contacts to pull the arc discharge, and the less likely the contacts will be burned , the longer the service life of the AC contactor. This function of the present embodiment is especially precious to high-power and high-priced AC contactors.

This is not the case with conventional AC contactors, which have no function of identifying randomly connected AC voltages, and it all depends on "luck". If you are lucky, if the AC voltage is connected when u=Umsin(ωt+φ)=Um, it will pull in strongly; but most of the time it is "bad luck". Let the absolute value of the minimum excitation voltage (that is, the absolute value of the minimum pull-in voltage) used to overcome the elastic force of the return spring be ∣u∣=∣Umsin(ωt+φ)∣=U0 then:

(1) If it is turned on when the instantaneous value of the AC voltage ∣u∣=∣Umsin(ωt+φ)∣=U0, it will pull in reluctantly and weakly;

(2) If the instantaneous value of the AC voltage ∣u∣=∣Umsin(ωt+φ)∣<U0 is connected, it will consume electricity in vain and cannot be pulled in, and it will consume electricity until the instantaneous value of the AC voltage rises to ∣ When u∣=∣Umsin（ωt＋φ）∣＝U0, it pulls in reluctantly and weakly.

This is one of the reasons why the contacts of conventional AC contactors, especially high-power and high-priced conventional AC contactors, often burn out, and it is also one of the reasons for high power consumption and temperature rise of conventional AC contactors.

2. Noise

In the holding phase of a conventional AC contactor, when the AC voltage input to the excitation coil is "zero-crossing" (the "zero-crossing point" when the AC voltage transitions from a positive half cycle to a negative half cycle or a negative half cycle to a positive half cycle), the instant near the zero point Voltage ∣u∣=∣Umsin(ωt+φ)∣<U0, the magnetic force generated by the exciting coil is less than the elastic force of the return spring, the moving iron core will leave the static iron core, but when it just leaves a small distance, the instantaneous AC voltage The value u has risen to ∣u∣=∣Umsin(ωt＋φ)∣>U0, so the moving iron core is pulled back by the magnetic force, and the moving and static iron cores are attracted again. During this process, the silicon steel sheets in the dynamic and static iron cores will generate mechanical vibration noise with a frequency of 100Hz (50Hz alternating current) or 120Hz (60Hz alternating current).

As mentioned above, in this embodiment, when the AC voltage "crosses zero", the capacitor C still has a certain voltage, and this voltage is discharged complementary to the exciting coil L, which can ensure that the electronic power-saving AC contactor maintains a stable holding state. Therefore, there is no mechanical vibration noise mentioned above. The silent and noiseless operation of the experimental prototype in this embodiment proves the correctness of the above analysis. Quiet operation is one of the functions of the present invention.

Three, power consumption

1. Conventional AC contactors are supplied with AC voltage (or full-time energization) in the holding state. The holding power provided by the AC voltage is too large, resulting in waste of electric energy and undue heating of the AC contactor;

2. In this embodiment, the AC voltage is only in the local time domain when the gas discharge tube GDT is discharged and turned on, such as the time domain from t2 to t3 (that is, the time domain where the conduction angle is Q1), and the time domain from t4 to t6 ( That is, the conduction angle is the time domain of Q2) to charge and store energy on the capacitor C and the excitation coil L, so the power consumption is much smaller than that of a conventional AC contactor. Saving electric energy is the most important function of the present invention.

4. Power factor

The excitation coil of a conventional AC contactor is an inductive device, so the power factor must be low.

In this embodiment, capacitors C are connected in parallel at both ends of the exciting coil L, and the inductive exciting coil L and the capacitive capacitor C compensate each other, so the power factor must be improved.

High power factor is also one of the functions of the present invention.

FIG. 13 is a schematic block diagram of Embodiment 2, and FIG. 14 is a schematic circuit diagram of Embodiment 2.

Combined with Figure 13, Figure 14: An electronic power-saving AC contactor, including two parts of an additional electronic unit 100 and a conventional AC contactor, characterized in that:

The conventional AC contactor is composed of a moving-break contact DD, a moving-closing contact DH, a moving iron core M, a static iron core G, a return spring F, and an excitation coil L;

The additional electronic unit 100 is a four-port network, with four ports N1, N2, P1, and P2, ports N1, N2 are two input ports, P1, P2 are two output ports; input ports N1, N2 is respectively connected to terminals S1 and S2 of the AC voltage, and output ports P1 and P2 are respectively connected to terminals A1 and A2 of the excitation coil L;

The inside of the four-port network additional electronic unit 100 is provided with a switch circuit 101 and an energy storage circuit 102, and its connection mode is: one end of the switch circuit 101 is connected to the N2 end, and the other end is connected to the P2 end. end, one end of the energy storage circuit 102 is connected to the P1 end, the other end is connected to the P2 end, and the P1 end is connected to the N1 end;

The switch circuit 101 is composed of a gas discharge tube GDT, and the energy storage circuit 102 is composed of a capacitor C;

The two electronic devices of the gas discharge tube GDT and the capacitor C form the four-port additional electronic unit 100;

The circuit structure and composition of the four-port additional electronic unit 100 are as follows: the N1 terminal, the P1 terminal, the capacitor C, the P2 terminal, the gas discharge tube GDT, and the N2 terminal are sequentially connected in series to form the four-port Additional electronics unit 100 .

Compared with the circuit structure of Embodiment 1, although the position of the gas discharge tube GDT in Embodiment 2 has been changed, the working principle and working process of Embodiment 2 are still the same as Embodiment 1, and will not be repeated here. stated.

Fig. 15 is the schematic circuit diagram of embodiment 3, and its circuit structure is: terminal N1, semiconductor discharge tube (solid discharge tube) TSS, terminal P1, capacitor C, terminal P2, terminal N2 are connected in series in sequence to form the additional electronic Unit 100;

In Embodiment 3, the gas discharge tube GDT in Embodiment 1 is replaced by a semiconductor discharge tube (solid discharge tube) TSS. Its working principle and working process are similar to those in Embodiment 1, and will not be repeated here.

16 is a schematic circuit diagram of Embodiment 4, and its circuit structure is as follows: the additional electronic unit 100 is composed of N1 terminal, P1 terminal, capacitor C, P2 terminal, electrostatic suppressor ESD, and N2 terminal connected in series in sequence.

In this embodiment 4, the gas discharge tube GDT in the embodiment 1 is replaced by an electrostatic suppressor ESD.

The above discloses the technical solution of the present invention, and has been described through the above-mentioned embodiments. Those skilled in the art should understand that: the above-mentioned embodiments are only illustrations of the present invention, and are not limited to the scope of the present invention described in the above-mentioned embodiments. Within the scope of protection defined in the Claims.

Claims (1)

1. an electron type power-saving alternating-current contactor, comprises additional electron unit and regular alternating current contactor two part, it is characterized in that:

Described regular alternating current contactor is made up of break contact (DD), make contact (DH), dynamic iron core (M), static iron core (G), back-moving spring (F), magnet exciting coil (L);

Described additional electron unit is four port networks, is provided with first input end mouth (N1), the second input port (N2), the first output port (P1) and the second output port (P2); First input end mouth (N1), the second input port (N2) are connected with the first end (S1) of AC voltage and the second end (S2) respectively, and the first output port (P1), the second output port (P2) are connected with the first end (A1) of described magnet exciting coil (L) and the second end (A2) respectively;

The inside of described additional electron unit is provided with switching circuit and accumulator; One end of the first input end mouth (N1) described in one termination of described switching circuit, the first output port (P1) described in another termination and described accumulator; Another termination second output port (P2) of described accumulator and the second input port (N2);

Wherein, described switching circuit is only made up of a gas discharge tube, and described accumulator is only made up of an electric capacity.