WO2019196523A1

WO2019196523A1 - Auxiliary power supply circuit and contactor applying same

Info

Publication number: WO2019196523A1
Application number: PCT/CN2019/070644
Authority: WO
Inventors: 苏俊熙
Original assignee: 深圳南云微电子有限公司
Priority date: 2018-04-12
Filing date: 2019-01-07
Publication date: 2019-10-17
Also published as: CN110379677A; CN110379677B

Abstract

An auxiliary power supply circuit and a contactor applying same. The auxiliary power supply circuit comprises a contactor coil, a transformer, a fly-wheel diode on the primary side of the transformer, and a switching circuit on the secondary side of the transformer, and a rectifying and filtering circuit. By collecting current flowing through an inter-turn capacitor of the contactor coil, performing energy conversion on the current by means of the transformer, and then using the current as the output of an auxiliary power supply, the problem of large loss of a linear power supply is solved. Moreover, the auxiliary power supply circuit is much simpler than a switching power supply, and does not need any additional control circuit.

Description

Auxiliary power supply circuit and contactor applying the same

Technical field

The present invention relates to the field of contactors, and more particularly to an auxiliary power supply circuit in a contact saver.

Background technique

The electromagnetic control system of the traditional contactor consists of a coil and an iron core. The number of turns of the coil is up to several hundred or even thousands of turns. The contactor coil is actually an inductor with a large inductance. Due to the large number of turns, the turn-to-turn capacitance of the coil is also large. The electrical model of the contactor coil is shown in Figure 1 and can be viewed as a large inductor in parallel with a small capacitor.

The circuit of Figure 2 is a known power saving circuit, and L1 is the coil of the contactor. The current of the contactor coil L1 can be adjusted by adjusting the duty ratio of the switching transistor TR1. Generally, the power-saving circuit with the control chip is powered by a linear power source, and the loss is relatively large. For example, the patent with the authorization announcement number is CN2563742Y, the application with the publication number CN101752143A, and the patent with the publication number CN1925085A. The control circuit is powered by a linear power supply. It is assumed that the chip power supply requires 2 mA of current. For the AC 220V input product, the rectifier filter The post-bus voltage is about 310V, then the loss of the control circuit is about 2mA*310V=0.61W. The higher the input voltage, the greater the loss.

With the development and promotion of semiconductor technology, the control circuit of the contactor power-saving circuit is also inevitably integrated. Generally, the internal logic circuit of the chip has a low withstand voltage, and the general power supply of 220V cannot directly supply power to the chip. The power management class control chip, the AC input application control chip generally has a high voltage start circuit inside, this high voltage start circuit is actually a linear power supply. Generally, such a control chip can be packaged in SOP-8. Since the chip is small in size and slow in heat dissipation, if the high-voltage start-up circuit continues to operate, the heat generation of the chip is severe, causing reliability problems. Therefore, the control chip of the switching power supply is generally powered by the auxiliary winding of the transformer, and the high-voltage starting circuit only works for a short period of time during the starting process, and does not cause serious heat generation problems.

However, in the field of contactor power saver, since the entire system has no transformer, the high voltage cannot be converted into a low voltage without damage. Therefore, the chip is powered by a linear power supply, but this causes heat generation. Or it is powered by a switching power supply, but the switching power supply circuit is complicated, and there may be more devices than the contactor power-saving circuit, which greatly increases the cost and volume.

Summary of the invention

The technical problem to be solved by the present invention is to provide an auxiliary power supply circuit and a contactor using the same, and only a few devices can be used to supply power to the contactor control circuit without using an additional control circuit, and the above can be completely omitted. Loss caused by linear power supplies.

In order to solve the above technical problem, the technical solution of the auxiliary power supply circuit of the present invention is as follows:

An auxiliary power supply circuit comprises a contactor coil, a transformer, a diode, a switch circuit and a rectification and filtering circuit; the transformer comprises a primary winding and a secondary winding; the input end of the contactor coil is an input end of the auxiliary power supply circuit, and the contact The output of the coil is connected to one end of the primary winding of the transformer; the anode of the diode is connected to the output of the contactor coil or the other end of the primary winding of the transformer, the cathode of the diode is connected to the input of the contactor coil; the input of the switching circuit is connected to the transformer The other end of the primary winding, the output end of the switching circuit is grounded, and the control end of the switching circuit is used to input a control signal; the two ends of the secondary winding of the transformer are respectively connected to the first input end and the second input end of the rectifying and filtering circuit, The second input end of the rectifying and filtering circuit is also connected to the ground, and the output end of the rectifying and filtering circuit is an output end of the auxiliary power supply circuit;

The switch circuit is turned on or off according to the control signal input from the control end thereof, and controls the transformer to transfer energy from the winding to the secondary winding while controlling the current of the contactor coil;

The transformer is used to transfer the energy of the primary winding to the secondary winding;

The rectifying and filtering circuit is used for rectifying and filtering the voltage of the secondary winding to obtain a smooth DC voltage, which is output to the output end of the auxiliary power supply circuit.

As an improvement of the above technical solution, the utility model further comprises an overvoltage prevention circuit, wherein an input end of the overvoltage prevention circuit is connected to an output end of the rectification filter circuit, an output end of the overvoltage prevention circuit is an output end of the auxiliary power supply circuit, and an overvoltage prevention circuit is used for Prevent the voltage output from the auxiliary power supply circuit from being too high.

Preferably, the switching circuit comprises an N-MOS transistor, the gate of the N-MOS transistor is its control terminal, the drain of the N-MOS transistor is its input terminal, and the source of the N-MOS transistor is For its output.

Preferably, the rectifying and filtering circuit comprises a diode and a capacitor, wherein the anode of the diode is its first input end, one end of the capacitor is its second input end, and the cathode of the diode is connected to the other end of the capacitor as a rectifying filter. The output of the circuit.

Preferably, the anti-overvoltage circuit is a Zener diode, the cathode of the Zener diode is an output end of the overvoltage prevention circuit, and the anode of the Zener diode is connected to the second input end of the rectification and filtering circuit.

Preferably, the anti-overvoltage circuit is a three-terminal voltage regulator, the input end of the three-terminal regulator is an input terminal of the overvoltage prevention circuit, and the output end of the three-terminal regulator is an output of the overvoltage prevention circuit. end.

The invention also provides a contactor applying the auxiliary power supply circuit, the input end of the auxiliary power supply circuit is connected to the input end of the contactor power saver, and the output end of the auxiliary power supply circuit is connected to the control circuit of the contactor power saver.

Compared with the prior art, the auxiliary power supply circuit of the present invention has the following beneficial effects:

The inventive concept of the present invention solves the problem of large linear power loss by collecting current flowing through the inter-turn capacitor of the contactor coil and performing energy conversion by the transformer as an auxiliary power supply; and the auxiliary power supply circuit of the present invention is also far more than The switching power supply is simple and requires no additional control circuitry.

DRAWINGS

Figure 1 electrical model of the contactor coil;

Figure 2 is a well-known power saving circuit;

Figure 3 is a circuit block diagram of the present invention;

Figure 4 is a schematic circuit diagram of a first embodiment of the present invention;

Figure 5 is a circuit waveform diagram of a first embodiment of the present invention;

Figure 6 is a circuit schematic diagram of a second embodiment of the present invention;

Figure 7 is a circuit schematic diagram of a third embodiment of the present invention;

Figure 8 is a circuit schematic diagram of a fourth embodiment of the present invention.

detailed description

3 is a circuit block diagram of the present invention, the auxiliary power supply circuit includes a contactor coil, a transformer, a switch circuit, a rectification filter circuit, and an overvoltage prevention circuit; the transformer includes a primary winding and a secondary winding; the contactor coil The input end is the input end of the auxiliary power supply circuit, and the output end of the contactor coil is connected to one end of the primary winding of the transformer; the input end of the switch circuit is connected to the other end of the primary winding of the transformer, the output end of the switch circuit is grounded, and the control of the switch circuit The end is used for inputting a control signal; one end and the other end of the secondary winding of the transformer are respectively connected to the first input end and the second input end of the rectifying and filtering circuit, and the second input end of the rectifying and filtering circuit is also connected to the ground, and the rectifying and filtering circuit is The output end is connected to the input end of the overvoltage prevention circuit, and the output end of the overvoltage prevention circuit is the output end of the auxiliary power supply circuit.

The switch circuit is turned on and off according to the control signal input from the control end thereof. While controlling the current of the contactor coil, the transformer is also controlled to transfer energy from the winding to the secondary winding; the transformer is used to turn the primary winding The energy is transmitted to the secondary winding, and the energy can be transmitted from the edge to the secondary side regardless of the position of the same name of the primary and secondary windings; the rectifier filter circuit is used to rectify and filter the voltage of the secondary winding to obtain a smooth DC voltage and output. To the overvoltage protection circuit; the transformer is used to transmit the energy of the primary winding to the secondary winding, and the energy can be transmitted from the edge to the secondary side regardless of the position of the same name of the primary and secondary windings; the output of the overvoltage circuit is prevented. The end is the output end of the auxiliary power supply circuit, and the overvoltage prevention circuit is used to prevent the voltage outputted by the auxiliary power supply circuit from being too high, and the control circuit of the contactor is protected.

It should be noted that FIG. 3 is a circuit block diagram of a preferred embodiment of the present invention. When the reliability requirement is not high or the control circuit of the contactor has been designed with an input overvoltage protection circuit, the overvoltage prevention circuit may not be required.

First embodiment

4 is a schematic diagram of an auxiliary power supply circuit according to a first embodiment of the present invention, including a contactor coil, a transformer T1, a diode D1, a diode D2, a capacitor C1, an N-MOS transistor TR1, and a Zener diode Z1, wherein the transformer T1 includes a a primary winding and a secondary winding; one end of the contactor coil is connected to the input voltage VIN of the contactor and the cathode of the diode D1, and the other end of the contactor coil is connected to the same end of the primary winding of the transformer T1; the primary winding of the transformer T1 The opposite end is connected to the drain of the N-MOS transistor TR1 and the anode of the diode D1, the source of the N-MOS transistor TR1 is grounded to GND, and the gate of the N-MOS transistor TR1 is used for inputting the control signal CTRL. The opposite end of the secondary winding of the transformer T1 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the ground GND via the capacitor C1. The Zener diode Z1 is connected in parallel with the capacitor C1, the anode of the Zener diode Z1 is grounded, and the cathode of the Zener diode Z1 is used as the output terminal VDD of the auxiliary power supply to supply power to the control circuit. The same name of the secondary winding of the transformer T1 is grounded to GND.

FIG. 5 is a circuit waveform diagram of the first embodiment, and the working principle of the circuit of the first embodiment is analyzed as follows:

T1-t2 phase: In this phase, the N-MOS transistor TR1 is turned on. Since the contactor coil has a large inter-turn capacitance, the N-MOS transistor is turned on and the inter-turn capacitor is charged to generate a large peak current, and the peak is sharp. The current is also stored in the edge inductance of transformer T1. Assuming that the peak value of the current is I _PPK , the inductance of the primary winding of the transformer T1 is L _P , and the energy stored in the primary winding of the transformer T1 is 1/2*I _PPK *L _P .

T2-t3 phase: During this phase, the current on the primary side of the transformer T1 needs to be freewheeling. The current can be freewheeled through two loops, one freewheeling loop is from the diode D1 to the contactor coil to the transformer T1 edge inductor, and the other freewheeling loop is the transformer T1 to transfer the current to the secondary side of the diode D2, capacitor C1 And secondary side inductance. Since the current of the contactor coil cannot be abruptly changed, the current of the transformer T1 cannot pass the diode D1 to the freewheeling circuit of the contactor coil. Therefore, the current of the transformer T1 can only be transmitted to the secondary side. Assuming that the turns ratio of the transformer T1 is N, the peak value of the secondary current is I _PPK *N.

T3-t4 stage: In this stage, the secondary winding of transformer T1 supplies energy to capacitor C2. Assuming that the supply voltage is V _DD and the secondary side inductance of transformer T1 is L _S , the duration of this phase is L _S *I _PPK *N/V _DD . There is no necessary connection between time point t4 and t5, and it is also possible that t4 time point is after t5.

T1-t5 stage: The input voltage is excited to the contactor coil, and the contactor coil current rises. The sense of the contactor coil is the hen-level, and the inductance of the transformer T1 is the millihenry level. The difference between the two is very large. The transformer T1 has little influence on the excitation current of the contactor coil and can be neglected. Therefore, the auxiliary supply current of the present invention has almost no effect on the original contactor power-saving circuit.

T5-t6 phase: During this phase, the N-MOS transistor is turned off, and the current of the contactor coil is continuously flowed through the diode D1. Due to the voltage drop of the diode D1, the current of the contactor coil is slowly decreased.

With the technical solution of the embodiment, it is assumed that the output voltage is 12V, the supply current is still 2 mA, and the loss is 24 mW, which is much smaller than the 440 mW using a linear power supply. Since the power level of the overall power supply is small, the transformer used in this embodiment is also small, and the core and the skeleton of EE 4.0 or less can be used, and the cost and volume are also small.

Second embodiment

Figure 6 is a schematic view showing an auxiliary power supply circuit of a second embodiment of the present invention. A second embodiment of the present invention includes a contactor coil, a transformer T1, a diode D1, a diode D2, a capacitor C1, an N-MOS transistor TR1, and a Zener diode Z1, wherein the transformer T1 includes a primary winding and a secondary winding; One end of the coil is connected to the input voltage VIN of the contactor and the cathode of the diode D1, and the other end of the contactor coil is connected to the same name end of the primary winding of the transformer T1 and the anode of the diode D1; the different end of the primary winding of the transformer T1 is The drain of the N-MOS transistor TR1 is connected, the source of the N-MOS transistor TR1 is connected to the ground GND, and the gate of the N-MOS transistor TR1 is used for inputting the control signal CTRL. The opposite end of the secondary winding of the transformer T1 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the ground GND via the capacitor C1. The Zener diode Z1 is connected in parallel with the capacitor C1, the anode of the Zener diode Z1 is grounded, and the cathode of the Zener diode Z1 is used as the output terminal VDD of the auxiliary power supply to supply power to the control circuit. The same name of the secondary winding of the transformer T1 is grounded to GND.

Compared with the first embodiment, the second embodiment has the same working principle and effect as the device used, and the connection of the diode D1 is different. Diode D1 is connected in parallel across the contactor coil. Since the current of the transformer can be freewheeled through the diode D2 on the secondary side, the winding of the edge will not induce excessive reverse voltage, and the N-MOS transistor TR1 will not generate a high peak voltage across the drain and source. normal work.

Third embodiment

FIG. 7 is a schematic diagram of an auxiliary power supply circuit according to a third embodiment of the present invention. A third embodiment of the present invention includes a contactor coil, a transformer T1, a diode D1, a diode D2, a capacitor C1, an N-MOS transistor TR1, and a three-terminal regulator, wherein the transformer T1 includes a primary winding and a secondary winding; One end of the coil is connected to the input voltage VIN of the contactor and the cathode of the diode D1, and the other end of the contactor coil is connected to the same end of the primary winding of the transformer T1; the different name end of the primary winding of the transformer T1 and the N-MOS tube TR1 The drain is connected to the anode of the diode D1, the source of the N-MOS transistor TR1 is connected to the ground GND, and the gate of the N-MOS transistor TR1 is used for inputting the control signal CTRL. The opposite end of the secondary winding of the transformer T1 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the ground GND via the capacitor C1. The IN terminal of the three-terminal regulator is connected to the connection point of the diode D2 and the capacitor C1. The OUT terminal of the three-terminal regulator supplies power to the control circuit as the output terminal VDD of the auxiliary power supply, and the GND terminal of the three-terminal regulator is grounded.

The third embodiment is different from the first embodiment in that the device for preventing the overvoltage circuit is different. In the third embodiment, the overvoltage prevention circuit is a three-terminal voltage regulator, and the working principle and the first embodiment of the third embodiment are the same. The embodiments are the same and will not be described here.

Fourth embodiment

FIG. 8 is a schematic diagram of an auxiliary power supply circuit according to a fourth embodiment of the present invention. A fourth embodiment of the present invention includes a contactor coil, a transformer T1, a diode D1, a diode D2, a capacitor C1, an N-MOS transistor TR1, and a Zener diode Z1, wherein the transformer T1 includes a primary winding and a secondary winding; One end of the coil is connected to the input voltage VIN of the contactor and the cathode of the diode D1, and the other end of the contactor coil is connected to the same end of the primary winding of the transformer T1; the different name end of the primary winding of the transformer T1 and the N-MOS tube TR1 The drain is connected to the anode of the diode D1, the source of the N-MOS transistor TR1 is connected to the ground GND, and the gate of the N-MOS transistor TR1 is used for inputting the control signal CTRL. The same name end of the secondary winding of the transformer T1 is connected to the anode of the diode D2, and the cathode of the diode D2 is grounded to the ground GND via the capacitor C1. The Zener diode Z1 is connected in parallel with the capacitor C1, the anode of the Zener diode Z1 is grounded, and the cathode of the Zener diode Z1 is used as the output terminal VDD of the auxiliary power supply to supply power to the control circuit, and the different name of the secondary winding of the transformer T1 is grounded to GND.

Compared with the first embodiment, the fourth embodiment has different positions of the same name end of the original secondary winding of the transformer T1, and the working principle is relatively different. In the first embodiment, during the turn-on of the N-MOS transistor TR1, energy is stored in the winding of the transformer T1, and when the N-MOS transistor TR1 is turned off, energy is transferred to the secondary winding of the transformer T1. . In the fourth embodiment, during the conduction of the N-MOS transistor TR1, the winding of the transformer T1 transfers energy to the secondary winding, and the N-MOS transistor TR1 turns off the device, and the transformer T1 does not transmit energy.

The above is only a preferred embodiment of the present invention, and it should be noted that the above-described preferred embodiments are not to be construed as limiting the scope of the invention, and the scope of the invention should be determined by the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and scope of the invention.

Claims

An auxiliary power supply circuit, comprising: a contactor coil, a transformer, a diode, a switch circuit and a rectifying and filtering circuit; the transformer comprises a primary winding and a secondary winding; the input end of the contactor coil is an auxiliary power supply circuit At the input end, the output end of the contactor coil is connected to one end of the primary winding of the transformer; the anode of the diode is connected to the output end of the contactor coil or the other end of the primary winding of the transformer, and the cathode of the diode is connected to the input end of the contactor coil; The input end is connected to the other end of the primary winding of the transformer, the output end of the switching circuit is grounded, and the control end of the switching circuit is used for inputting a control signal; the two ends of the secondary winding of the transformer are respectively connected with the first input end and the second of the rectifying and filtering circuit The input end is connected, the second input end of the rectifying and filtering circuit is also connected to the ground, and the output end of the rectifying and filtering circuit is an output end of the auxiliary power supply circuit;

The switch circuit is turned on or off according to the control signal input from the control end thereof, and controls the transformer to transfer energy from the winding to the secondary winding while controlling the current of the contactor coil;

The transformer is used to transfer the energy of the primary winding to the secondary winding;

The rectifying and filtering circuit is used for rectifying and filtering the voltage of the secondary winding to obtain a smooth DC voltage, which is output to the output end of the auxiliary power supply circuit.
The auxiliary power supply circuit according to claim 1, further comprising an overvoltage prevention circuit, wherein the input end of the overvoltage prevention circuit is connected to the output end of the rectification filter circuit, and the output end of the overvoltage prevention circuit is an output of the auxiliary power supply circuit. The overvoltage prevention circuit is used to prevent the voltage output from the auxiliary power supply circuit from being too high.
The auxiliary power supply circuit according to claim 1, wherein said switching circuit comprises an N-MOS transistor, and a gate of the N-MOS transistor is a control terminal thereof, and a drain of the N-MOS transistor is At the input, the source of the N-MOS transistor is its output.
The auxiliary power supply circuit according to claim 1, wherein said rectifying and filtering circuit comprises a diode and a capacitor, wherein the anode of the diode is its first input end, and one end of the capacitor is its second input end. The cathode of the diode is connected to the other end of the capacitor as the output of the rectifying and filtering circuit.
The auxiliary power supply circuit according to claim 2, wherein said anti-overvoltage circuit is a Zener diode, the cathode of the Zener diode is an output terminal of the overvoltage prevention circuit, and the anode of the Zener diode is connected to the rectification filter. The second input of the circuit.
The auxiliary power supply circuit according to claim 2, wherein said overvoltage prevention circuit is a three-terminal voltage regulator, and the input end of the three-terminal voltage regulator is an input terminal of the overvoltage prevention circuit, and the three terminals are stable. The output of the voltage regulator is the output of the overvoltage prevention circuit.
A contactor for applying the auxiliary power supply circuit according to any one of claims 1 to 6, characterized in that the input end of the auxiliary power supply circuit is connected to the input end of the contactor power saver, and the output end of the auxiliary power supply circuit is connected to the contactor section The control circuit of the appliance.