WO2019134123A1

WO2019134123A1 - Switch power supply circuit

Info

Publication number: WO2019134123A1
Application number: PCT/CN2018/071593
Authority: WO
Inventors: 孟加顷
Original assignee: 孟加顷
Priority date: 2018-01-05
Filing date: 2018-01-05
Publication date: 2019-07-11

Abstract

A switch power supply circuit, comprising an alternating current power supply input terminal (10), a common-mode interference filter circuit (20), an alternating current rectifying circuit (30), a high-voltage electrolytic capacitor (C2), a filter anti-interference circuit (50), a peak absorption circuit (60), an energy converting circuit (70), a low-voltage rectifying circuit (80), a low-voltage peak filter circuit (90), and a direct current power supply output terminal (100). The switch power supply circuit performs pertinent positional movements and combinations of three devices: an X capacitor (C1), a transient voltage inhibiting device pressure-sensitive resistor (VR) and a discharging resistor (R), such that the entire power supply is improved in all aspects, such as interference resistance, accuracy, conversion efficiency, service life, and low failure rate; resistor (R1) and capacitor (C3) parameters in the absorption circuit (60) dedicated to absorbing leakage inductance counter electromotive force energy of a transformer are adjusted, thus improving the conversion efficiency of the power supply; resistor (R2) and capacitor (C4) parameters in an absorption circuit (110) for a low voltage side are adjusted, thus further improving the conversion efficiency of the power supply.

Description

Switching power supply circuit

Technical field

The invention relates to the technical field of electrical equipment power supply, in particular to a switching power supply circuit.

Background technique

In various switching power supply circuits composed of a pulse width modulation (PWM) control chip, a high frequency transformer and a MOSFET switch tube, a high frequency filtering portion composed of an X capacitor and a discharge resistor is generally used at an input end of the AC power source. Since an unreasonable safety test standard has been used (the capacitor discharge device of the primary circuit should be designed to be disconnected outside the AC power supply, minimizing the electric shock caused by the charge stored in the capacitor connected to the primary circuit) DANGER, check the equipment and the relevant circuit diagram to verify its eligibility. Check that the on/off switch may be in any position when the power is turned off. If there is any capacitor in the equipment, the indicated or nominal capacity exceeds 0.1. uF, and connected to a circuit, but the discharge time constant of the capacitor does not exceed the following specified values, the equipment should be considered qualified: - for Type A pluggable devices: 1 second; and - for permanent connections Device and type B pluggable device: 10 seconds; the relevant time constant refers to the product of equivalent capacitance (uF) and equivalent discharge resistance (MΩ), if measured If it is difficult to determine the equivalent capacitance and resistance value, the voltage attenuation can be measured at the external disconnect point. Note: After a period equal to a time constant, the voltage will decay to 37% of the initial value, so that this part of the filter is resistant. The interference effect is extremely limited, because under the current test standard, the product of the X capacitor and the discharge resistor represents a discharge time constant that is much larger than the sinusoidal half cycle of the alternating current, and the voltage obtained by charging each alternating current half cycle of the X capacitor is always It is far from being released in a half cycle, and finally causes high peak interference on the X capacitor, which is applied to all circuits in the latter stage, which eventually leads to various failure problems of the device; if the resistance of the discharge resistor is lowered, Bringing the problem of increased power consumption and increased resistance volume of this filtering part, and still can not solve the core problem of the core - after the rectifier bridge, the high voltage electrolytic capacitor BUG2 will cause the transformer to produce a peak anti-electromotive interference peak at any time. Not completely suppressed.

Since the MOSFET switch tube is damaged by preventing the high back-EM potential caused by the high-frequency on-off caused by the leakage inductance of the high-frequency transformer, a spike absorbing circuit composed of a resistor, a capacitor, and a diode is used, and the operation itself is absorbed. In addition, a considerable amount of electric energy must be consumed. In the rectifier circuit on the low-voltage side, in order to quickly recover the Schottky diode, an absorbing circuit composed of a resistor and a capacitor is also used, which also consumes a certain amount of electric energy, and the excessively consumed electric energy is caused. The overall energy conversion efficiency is low.

As shown in FIG. 1, the circuit structure commonly used in the existing switching power supply has the following disadvantages:

Disadvantage 1: The main disadvantage of BUG1 is the shortcomings caused by the imperfect existing safety test standards, but this shortcoming has not attracted attention. The key point of this shortcoming is: X capacitor C1 and discharge resistor R The circuit, whose discharge time constant is much larger than the sinusoidal half cycle time of the alternating current of 50 (or 60) Hz, can be proved by experiments that under the current safety test standard requirements, the excessive discharge time constant will always be at the capacitance C1. The spikes surged at both ends and are transmitted to the entire post-stage circuit of the power supply. The failure of the electronics in the subsequent stage is generally related to this. - Following this part, the adjacent chokes are unlikely to have an infinite high inductance (common mode inductance), so the suppression of high frequency spikes will be very limited.

Disadvantage 2: The main disadvantage of BUG2 is that high-voltage electrolytic capacitor C2 inevitably has internal resistance and internal inductance regardless of the electrolytic capacitor of any quality. These internal resistance and internal inductance are high-frequency high-voltage interference. There is no filtering effect, which in turn leaves a problem for the transmission to the subsequent stage circuit.

Disadvantage 3: The disadvantage of BUG3 is that this part of the circuit absorbs a part of the peak high-frequency interference, and can not effectively absorb all the peak high-frequency interference, and inevitably consumes a part of the energy, which lowers the energy of the whole power supply. Conversion efficiency.

Disadvantage 4: The main disadvantage of BUG4 is that the high-frequency transformer B will always have a certain leakage inductance. In the high-speed on-off process of the MOSFET switch tube, an unavoidable back electromotive force will be generated. When this counter electromotive force is too high, it cannot be absorbed. The circuit absorption, which will be applied to the MOSFET switch, may cause breakdown breakdown of the MOSFET switch.

Disadvantage 5: The main disadvantage of BUG5 is that this part of the circuit also consumes a certain amount of energy, which lowers the conversion efficiency of the entire power supply.

Disadvantage 6: The main disadvantage of BUG6 is that the breakdown voltage of the MOSFET switch tube is always limited, and will be aging in the continuous interference impact to reduce the performance. It is often possible to pass the spike interference through the transformer B before it is damaged. The transmission to the subsequent stage circuit poses a substantial threat to the latter stage circuit.

Summary of the invention

In order to solve the above problems, the present invention proposes a circuit structure adjustment scheme of a switching power supply, and forms a new switching power supply circuit, so that the entire power supply is comprehensive in terms of anti-interference, accuracy and conversion efficiency, service life, and low failure rate. A switching power supply circuit with improved power conversion efficiency.

The invention is achieved by the following technical solutions:

The present invention provides a switching power supply circuit, which is disposed in a switching power supply device for filtering a current between a power input end and a power output end of the switching power supply device, wherein the switching power supply circuit includes an AC power input end Common mode interference filter circuit, AC rectifier circuit, high voltage electrolytic capacitor C2, filter anti-interference circuit, spike absorption circuit, energy conversion circuit, low voltage rectifier circuit, low voltage spike filter circuit, DC power output terminal;

The AC power input terminal inputs an AC mains power, the common mode interference filter circuit is connected between the AC power input end and the AC rectification circuit, and the AC rectification circuit is connected in parallel to the high voltage electrolytic capacitor C2. The filter anti-interference circuit is connected in parallel with the high voltage electrolytic capacitor C2, and the peak absorption circuit is connected between the filter anti-interference circuit and the energy conversion circuit, and the low voltage rectifier circuit processes the energy conversion circuit The output electrical signal is rectified, and the low voltage spike filtering circuit filters and removes the electrical signal processed by the low voltage rectifying circuit, and the DC power output end is connected to the low voltage spike filtering circuit, and the DC power output end Output DC current;

The filter anti-interference circuit includes an X capacitor C1, a transient voltage suppression device varistor VR, and a discharge resistor R. The transient voltage suppression device varistor VR is connected in series with the discharge resistor R, and the X capacitor C1 and The transient voltage suppression device varistor VR is connected in parallel with the series circuit of the discharge resistor R, and the filter anti-interference circuit is used for suppressing interference and harmonics generated by the circuit.

Further, the switching power supply circuit further includes a low voltage absorption circuit, the low voltage absorption circuit and the low voltage finishing circuit are connected in parallel, and the low voltage absorption circuit includes a discharge resistor R2 and a capacitor C4 connected in series.

Further, the switching power supply circuit further includes a low voltage filter circuit, the low voltage filter circuit and the low voltage spike filter circuit are connected in parallel, and the low voltage filter circuit is sandwiched between the low voltage spike filter circuit and the DC power output. Between the ends.

Further, the low voltage filter circuit includes a capacitor C5 connected in parallel, and the low voltage filter circuit is configured to filter the electrical signal processed by the low voltage rectifier circuit.

Further, the switching power supply circuit further includes a feedback and control unit, and the feedback and control unit is connected to one end of the peak absorbing circuit for performing feedback information on the switching power supply circuit.

Further, one end of the high voltage electrolytic capacitor C2 is grounded.

Further, the filter anti-interference circuit is grounded at one end.

Further, the peak absorbing circuit includes a discharge resistor R1, a capacitor C3, and a diode D1. The discharge resistor R1 and the capacitor C3 are connected in parallel. The diode D1 and the discharge resistor R1 and the capacitor C3 are connected in parallel. The circuits are connected in series, and the peak absorbing circuit is used to increase the conversion efficiency of the energy conversion circuit.

Further, the low voltage rectifier circuit comprises a diode D2, and the low voltage rectifier circuit performs a low voltage rectification process on the electrical signal converted by the energy conversion circuit.

Further, the low voltage spike filter circuit is connected in parallel with a capacitor C6, and the low voltage spike filter circuit is configured to filter the electrical signal processed by the low voltage rectifier circuit.

The beneficial effects of the invention:

The switching power supply circuit of the present invention moves and combines the targeted positions of the three devices of the X capacitor C1, the transient voltage suppression device varistor VR and the discharge resistor R, and the source of the transformer back electromotive force that causes the switching power supply to fail. - The peak interference at the high-voltage electrolytic capacitor C2 is extremely thoroughly suppressed, so that the entire power supply has been comprehensively improved in terms of anti-interference, accuracy and conversion efficiency, and service life, low failure rate, etc. The resistance and capacitance parameters in the absorption circuit of the electromotive force are adjusted to improve the power conversion efficiency; the resistance and capacitance parameters in the absorption circuit on the low voltage side are adjusted to further improve the power conversion efficiency.

DRAWINGS

1 is a schematic diagram of a conventional switching power supply circuit;

2 is a schematic diagram of a switching power supply circuit of the present invention.

Detailed ways

In order to explain the technical solutions of the present invention more clearly and completely, the present invention will be further described below in conjunction with the accompanying drawings.

Referring to FIG. 2, the present invention provides a switching power supply circuit, which is disposed in a switching power supply device for filtering a current between a power input end and a power output end of the switching power supply device, where the switching power supply circuit The utility model comprises an AC power input terminal 10, a common mode interference filter circuit 20, an AC rectifier circuit 30, a high voltage electrolytic capacitor C240, a filter anti-interference circuit 50, a peak absorption circuit 60, an energy conversion circuit 70, a low voltage rectifier circuit 80, and a low voltage peak filter circuit 90. The DC power output terminal 100, the common mode interference filter circuit 20 includes a choke coil L1.

The AC power input terminal 10 inputs AC mains, the common mode interference filter circuit 20 is connected between the AC power input terminal 10 and the AC rectification circuit 30, and the AC rectification circuit 30 is connected in parallel to the a high voltage electrolytic capacitor C240, the filter anti-interference circuit 50 is connected in parallel with the high voltage electrolytic capacitor C240, and the peak absorption circuit 60 is connected between the filter anti-interference circuit 50 and the energy conversion circuit 70, the low voltage rectification The circuit 80 rectifies the output electrical signal processed by the energy conversion circuit 70, and the low voltage spike filtering circuit 90 filters and removes the electrical signal processed by the low voltage rectifier circuit 80, the DC power output terminal 100 and The low voltage spike filter circuit 90 is connected, and the DC power output terminal 100 outputs a direct current.

The filter anti-interference circuit 50 includes an X capacitor C1, a transient voltage suppression device varistor VR, and a discharge resistor R. The transient voltage suppression device varistor VR is connected in series with the discharge resistor R, and the X capacitor C1 And the transient voltage suppression device varistor VR is connected in parallel with the series circuit of the discharge resistor R, and the filter anti-interference circuit 50 is used for suppressing interference and harmonics generated by the circuit.

Further, the switching power supply circuit further includes a low voltage absorption circuit 110, the low voltage absorption circuit 110 and the low voltage finishing circuit are connected in parallel, and the low voltage absorption circuit 110 includes a discharge resistor R2 and a capacitor C4 connected in series.

Further, the switching power supply circuit further includes a low voltage filter circuit 120, the low voltage filter circuit 120 and the low voltage spike filter circuit 90 are connected in parallel, and the low voltage filter circuit 120 is sandwiched between the low voltage spike filter circuit 90 and Between the DC power output terminals 100.

Further, the low-voltage filter circuit 120 includes a capacitor C5 connected in parallel, and the low-voltage filter circuit 120 is configured to filter the electrical signal processed by the low-voltage rectifier circuit 80.

Further, the switching power supply circuit further includes a feedback and control unit 130, and the feedback and control unit 130 is connected to one end of the peak absorbing circuit 60 for performing feedback information on the switching power supply circuit.

Further, the high voltage electrolytic capacitor C240 is grounded at one end.

Further, the filter anti-interference circuit 50 is grounded at one end.

Further, the peak absorbing circuit 60 includes a discharge resistor R1, a capacitor C3, and a diode D1. The discharge resistor R1 and the capacitor C3 are connected in parallel. The diode D1 and the discharge resistor R1 are connected in parallel with the capacitor C3. The branches are connected in series, and the peak absorbing circuit 60 is used to increase the conversion efficiency of the energy conversion circuit 70.

Further, the low voltage rectifier circuit 80 includes a diode D2, and the low voltage rectifier circuit 80 performs a low voltage rectification process on the electrical signal converted by the energy conversion circuit 70.

Further, the low voltage spike filter circuit 90 is connected in parallel with a capacitor C6, and the low voltage spike filter circuit 90 is configured to filter the electrical signal processed by the low voltage rectifier circuit 80.

In this embodiment, the filter anti-interference circuit 50 is provided to adjust the three devices of the X capacitor C1, the discharge resistor R, and the varistor VR to a position adjacent to the high voltage electrolytic capacitor C240, where the three devices are located. It will play a key role as described below:

(1) C1 acts as a low-resistance, low-inductance capacitor that absorbs high-frequency spikes from the power supply side of the grid. On the other hand, it also absorbs the back-EMF energy generated by the leakage inductance of the transformer, which will generally make the key shown in the figure. The high-frequency ripple of point P is greatly reduced, and the key processing is improved for the stability of the entire power supply circuit. The accuracy of the power output and the conversion efficiency will be significantly improved. At the same time, according to actual needs, in the application, different capacitors of such capacity (low internal resistance, low internal inductance) can be used in parallel to achieve better results.

(2) The role of the varistor VR here is also from the front and the back, while limiting the spike voltage from the grid and the back EMF spike of the transformer, so that these harmful spikes are always in a safe range. It does not pose a breakdown of the MOSFET tube, nor does it transmit too high a spike voltage to the subsequent stage, ensuring the safety of the entire power supply circuit. The present invention is not limited to the varistor, and the related device which suppresses the transient voltage can also have the same effect.

(3) The function of the discharge resistor R is to effectively suppress the large current impact on the varistor when the peak voltage occurs. Due to the natural limitations of the manufacturing materials and the production process, the varistor may always be damaged by the transient excessive current. In order to avoid this possibility, after the discharge resistance R of the appropriate resistance is connected in series, the limitation of the peak voltage can be ensured, and the damage caused by the excessive current can be avoided, which has an economical and practical effect. It should be pointed out here that the resistance value of this discharge resistor R is completely different from the large resistance value under the premise of the existing problem standard. It is recommended to be in the range of several tens of ohms, which can enhance the transient such as varistor. The overcurrent capability of the voltage suppression device can also control the suppression voltage value raised by the presence of the resistance within the target range, thereby achieving an ideal target effect.

In the present embodiment, a peak absorbing circuit 60 is provided. The peak absorbing circuit 60 includes a discharge resistor R1, a capacitor C3, and a diode D1. The discharge resistor R1 and the capacitor C3 are connected in parallel. The diode D1 and the discharge resistor are arranged. R1 is connected in series with the parallel branch of the capacitor C3. Due to the action of the filter anti-interference circuit 50 on the electrical signal in the circuit, the harmful energy that the peak absorption circuit 60 needs to absorb is significantly weakened, so the peak absorption circuit 60 is adjusted. The parameter reduces the value of the capacitor C3 and increases the resistance of the discharge resistor R1. After the energy consumed by the peak absorbing circuit 60 is lowered, the conversion efficiency of the entire switching power supply is further improved.

In the present embodiment, the low-voltage absorption circuit 110 functions as the peak absorption circuit 60. After the corresponding adjustment of the low-voltage absorption circuit 110, the conversion efficiency of the entire power supply is further improved. In some applications, this portion of the absorption is enhanced. The circuit can even be cancelled.

In the embodiment, the capacitor C6 connected to the low-voltage spike filter circuit 90 is also a low-resistance and low-inductance high-frequency filter capacitor. In position, one end should be as close as possible to D2, and the other end should be as close as possible to the DC power output. 100 transformer terminal with the same polarity, which plays a key role in further absorbing the ripple of this part of the power supply, further improving the quality and efficiency of the power supply.

In the present embodiment, the switching power supply circuit of the present invention performs the three devices of the X capacitor C1, the transient voltage suppression device varistor VR, and the discharge resistor R, compared to the circuit configuration commonly used in the conventional switching power supply. Targeted position movement and combination, the entire power supply has been comprehensively improved in terms of anti-interference, accuracy and conversion efficiency, and service life and low failure rate.

In the present embodiment, the resistance R1 and the capacitance C3 parameters in the absorption circuit (ie, the peak absorption circuit 60) dedicated to absorbing the leakage inductance back electromotive force of the transformer are adjusted to improve the power conversion efficiency.

In the present embodiment, adjustments are made to the parameters of the resistor R2 and the capacitor C4 in the low-voltage side absorption circuit (ie, the low-voltage absorption circuit 110) to further improve the power conversion efficiency.

In the present embodiment, compared with the existing circuit structure, only one capacitor C6 needs to be added, and the cost is low; and the improvement of the power quality performance is comprehensive, and the accuracy, the anti-interference ability, and the conversion efficiency are all obtained. Extremely obvious improvement, the effect is remarkable; for the switching power supply commonly used in electrical equipment of various industries, the power supply product with comprehensive improvement in performance and quality life can be obtained by adopting the invention in a very low cost manner, and the application value is large. .

Of course, there are other embodiments that can be implemented by the present invention. Based on the present embodiment, other embodiments obtained by those skilled in the art without any creative work are within the scope of the present invention.

Claims

A switching power supply circuit is disposed in the switching power supply device for filtering current between the power input end and the power output end of the switching power supply device, wherein the switching power supply circuit comprises an AC power input End, common mode interference filter circuit, AC rectification circuit, high voltage electrolytic capacitor C2, filter anti-interference circuit, spike absorption circuit, energy conversion circuit, low voltage rectifier circuit, low voltage spike filter circuit, DC power output terminal;

The AC power input terminal inputs an AC mains power, the common mode interference filter circuit is connected between the AC power input end and the AC rectification circuit, and the AC rectification circuit is connected in parallel to the high voltage electrolytic capacitor C2. The filter anti-interference circuit is connected in parallel with the high voltage electrolytic capacitor C2, and the peak absorption circuit is connected between the filter anti-interference circuit and the energy conversion circuit, and the low voltage rectifier circuit processes the energy conversion circuit The output electrical signal is rectified, and the low voltage spike filtering circuit filters and removes the electrical signal processed by the low voltage rectifying circuit, and the DC power output end is connected to the low voltage spike filtering circuit, and the DC power output end Output DC current;

The filter anti-interference circuit includes an X capacitor C1, a transient voltage suppression device varistor VR, and a discharge resistor R. The transient voltage suppression device varistor VR is connected in series with the discharge resistor R, and the X capacitor C1 and The transient voltage suppression device varistor VR is connected in parallel with the series circuit of the discharge resistor R, and the filter anti-interference circuit is used for suppressing interference and harmonics generated by the circuit.
The switching power supply circuit according to claim 1, wherein said switching power supply circuit further comprises a low voltage absorbing circuit, said low voltage absorbing circuit and said low voltage sizing circuit are connected in parallel, said low voltage absorbing circuit comprising discharge resistors connected in series R2 and capacitor C4.
The switching power supply circuit according to claim 1, wherein the switching power supply circuit further comprises a low voltage filter circuit, the low voltage filter circuit and the low voltage spike filter circuit are connected in parallel, and the low voltage filter circuit is The low voltage spike filter circuit and the DC power output end.
The switching power supply circuit according to claim 3, wherein the low voltage filter circuit comprises a capacitor C5 connected in parallel, and the low voltage filter circuit is configured to filter the electrical signal processed by the low voltage rectifier circuit.
The switching power supply circuit according to claim 1, wherein said switching power supply circuit further comprises a feedback and control unit, said feedback and control unit being coupled to one end of said peak absorbing circuit for said switch The power circuit performs feedback information.
The switching power supply circuit according to claim 1, wherein one end of said high voltage electrolytic capacitor C2 is grounded.
The switching power supply circuit according to claim 1, wherein the filter anti-interference circuit is grounded at one end.
The switching power supply circuit according to claim 1, wherein said peak absorbing circuit comprises a discharge resistor R1, a capacitor C3, and a diode D1, said discharge resistor R1 and said capacitor C3 being connected in parallel, said diode D1 and said The discharge resistor R1 is connected in series with the parallel branch of the capacitor C3, and the peak absorption circuit is used to improve the conversion efficiency of the energy conversion circuit.
The switching power supply circuit according to claim 1, wherein the low voltage rectifying circuit comprises a diode D2, and the low voltage rectifying circuit performs a low voltage rectification process on the electric signal converted by the energy converting circuit.
The switching power supply circuit according to claim 1, wherein the low-voltage spike filter circuit is connected in parallel with a capacitor C6, and the low-voltage spike filter circuit is configured to filter the electrical signal processed by the low-voltage rectifier circuit.