CN215528878U - Switching power supply device - Google Patents

Abstract

The utility model discloses a switch power supply device, which comprises a filter unit and a DCDC unit, wherein the filter unit comprises a capacitor C1, a capacitor C2 with the withstand voltage value lower than that of a capacitor C1, an inductor L, a diode D1, a diode D2, a switch S1 and a controller M1, the filter unit provides power supply and input voltage detection through the DCDC unit, and simultaneously detects the current flowing through a switch S1, the controller M1 is provided with a voltage preset value corresponding to the input voltage and a current preset value corresponding to the working current of a switch S1, the state of the switch S1 is controlled in real time by judging the size relation between the detected voltage and current and the corresponding preset value, the capacitor connected into a circuit for filtering is adjusted, the high-voltage small-capacity capacitor C1 and the low-voltage large-capacity capacitor C2 are fully utilized, the impact current of the low-voltage large-capacity capacitor C2 is limited, and the utility model is applied to the switching power supply of the ACDC switch with wider input voltage range, the number of filter capacitors can be effectively reduced, and the product volume and the cost can be reduced.

Description

Switching power supply device

Technical Field

The utility model relates to the field of ACDC switching power supplies, in particular to an ACDC switching power supply with a wide input voltage range.

Background

The switching power supply has the advantages of light weight, small volume and high efficiency, and is widely applied to various fields such as aviation, aerospace, railways, electric power, communication, consumer electronics and the like. With the progress of technology, in addition to meeting basic performance, the requirements on the size and cost of a switching power supply are stricter in some application occasions. At present, an ACDC switching power supply generally adopts a basic architecture shown in fig. 1, an input side of the power supply is connected with an alternating current power supply, and an alternating current voltage is firstly shaped into a pulsating direct current voltage through a rectifying unit; secondly, converting the pulsating direct current voltage into direct current voltage with smaller pulsation amplitude through a filtering unit; and finally, stable direct-current voltage output is realized through the DCDC converter and is supplied to a rear-stage load. For an ACDC switching power supply with a wide input voltage range, for example, in an application situation where the input voltage range is 85VAC to 460VAC, during design, the withstand voltage of a capacitor of a filtering unit is usually selected according to the highest input voltage of 460VAC, and at this time, the peak value of the rectified ac voltage is 650V, so that two standard capacitors with withstand voltage of 400V are generally selected to be used in series; at the lowest input voltage of 85VAC, the capacitance in the filtering unit must have a large enough capacity to avoid the situation that the valley value of the bus voltage is too low to cause the subsequent stage DCDC converter to be unable to work, so that a plurality of capacitors are required to be used in parallel. In order to meet the design requirements of high-voltage input and low-voltage input at the same time, a common method is to connect two 400V-withstand-voltage capacitors in series to form a group of withstand-voltage-satisfying capacitors (called high-voltage capacitors for short), and then connect a plurality of groups of high-voltage capacitors in parallel to satisfy the capacity requirements.

It should be noted that the capacitor is used as an energy storage element, and the energy storage capacity is in direct proportion to the capacitance value and in direct proportion to the square of the voltage. Thus, for equivalent power requirements, the capacitance capacity required is larger when the input voltage is lower and smaller when the input voltage is higher. Then, for the ACDC switching power supply with a wide input range, after the capacitance capacity is satisfied by connecting multiple groups of high-voltage capacitors in parallel according to the requirement of low-voltage input, the capacitance of the capacitor gradually becomes redundant with the increase of the input voltage, which may cause the problems of large number of capacitors in the filtering unit, large volume and high cost, and further cause the problems of large volume and high cost of the ACDC switching power supply.

SUMMERY OF THE UTILITY MODEL

In view of this, the present invention provides a switching power supply device, which can effectively solve the problems of large size and high cost of the conventional wide-input ACDC switching power supply.

The conception of the utility model is as follows: the capacitor of a filter unit in the conventional ACDC switching power supply device is designed into a high-voltage small-capacity capacitor C1 meeting a high-voltage section and a low-voltage large-capacity capacitor C2 meeting a low-voltage section, the input voltage of a DCDC unit is detected by an auxiliary winding of a transformer of the DCDC unit, and when the input voltage of the DCDC unit is in a lower range, C1 and C2 work in parallel; when the input voltage of the DCDC unit is in the higher range, C1 works alone.

In order to achieve the purpose, the utility model is realized by the following technical scheme:

the utility model provides a switching power supply device, which is applied to a switching power supply and comprises a filtering unit and a DCDC unit, wherein the filtering unit comprises a positive input end Vin +, a negative input end Vin-, a positive output end Vo + and a negative output end Vo-, the filtering unit is connected with the positive input end Vin + and the negative input end Vin-, and is also connected with the DCDC unit; the filter unit comprises a capacitor C1, a switch S1, an inductor L, a diode D1, a diode D2, a capacitor C2 and a controller M1, wherein the withstand voltage of the capacitor C2 is different from that of a capacitor C1, the anode of a capacitor C1 is connected with an anode input terminal Vin +, the cathode of a capacitor C1 is connected with a cathode input terminal Vin-, the anode of a capacitor C2 is connected with the anode input terminal Vin +, the cathode of a capacitor C2 is connected with the cathode of a diode D2 and one end of the inductor L, the anode of a diode D2 is connected with the cathode input terminal Vin-, the other end of the inductor L is connected with the anode of a diode D1 and the drain of a switch S1, the cathode of a diode D1 is connected with the anode input terminal Vin +, the source of a switch S1 is connected with the cathode input terminal Vin-and a current sampling terminal V3 of the controller M1, a current sampling terminal V3 of a controller M1 detects the source current of the switch S1, the gate of the switch S1 is connected with a driving output terminal V4 of the controller M1, a power supply end V1 of the controller M1 is connected with the DCDC unit, a voltage detection end V2 of the controller M1 is connected with the DCDC unit and used for detecting the output voltage of the switching power supply device, and a reference ground GND of the controller M1 is connected with a negative electrode input end Vin < - >; the DCDC unit is used for realizing stable direct-current voltage output and supplying the stable direct-current voltage output to a load at the rear stage of the switching power supply device.

Specifically, the capacitor C1 is a small-capacity capacitor whose withstand voltage satisfies the highest input voltage of the switching power supply device, and the capacitor C2 is a large-capacity capacitor whose withstand voltage is lower than the capacitor C1.

Preferably, the voltage preset value is variable.

As a specific implementation of the controller M1, the controller M1 includes a diode D5, a capacitor C5, a resistor R1, a resistor R2, a resistor R3, a zener diode D6, a voltage regulator K, and a logic processing module; the anode of the diode D5 is used as a voltage detection terminal V2 of the controller M1, the cathode of the diode D5 is connected with one end of a resistor R1 and the anode of a capacitor C5, the other end of the resistor R1 is connected with one end of a resistor R2 and the sampling terminal of a voltage regulator K, the output terminal of the voltage regulator K is connected with one end of a resistor R3, the cathode of a zener diode D6 and a logic processing module, the logic processing module further has an input terminal which is used as a current sampling terminal V3 of the controller M1, the logic processing module further includes an output terminal which is used as a driving output terminal V4 of the controller M1, the other end of the resistor R3 is used as a power supply terminal V1 of the controller M1, the cathode of the capacitor C5, the other end of the resistor R2, the reference ground of the voltage regulator K and the anode of the zener diode D6, and the connection point is used as a reference ground GND with the controller M1.

Specifically, the logic processing module has two input signals, which are respectively input by the output end of the voltage regulator K and the source electrode of the switch S1.

Specifically, the filter unit specifically functions to detect the current of the switch S1 and the input voltage of the switching power supply device, set a voltage preset value according to the withstand voltage value of the capacitor C2, set a current preset value according to the current specification of the switch S1, when the input voltage is higher than the voltage preset value, the controller M1 controls the switch S1 to be in an off state, when the input voltage is lower than the voltage preset value and the current of the switch S1 is smaller than the current preset value, the controller M1 controls the switch S1 to be in an on or high-frequency switching state, and when the input voltage is lower than the voltage preset value and the current sampling value of the switch S1 is greater than the current preset value, the controller M1 controls the switch S1 to be in an off state.

Preferably, the voltage regulator further comprises a zener diode D7, a resistor R5, a resistor R6 and a transistor T1, wherein the cathode of the zener diode D7 is connected to the output end of the regulator K, one end of the resistor R5 is connected to the sampling end of the regulator K, the emitter of the transistor T1 is connected to the other end of the resistor R5, the base of the transistor T1 is connected to the anode of the zener diode D7 and one end of the resistor R6, and the collector of the transistor T1 and the other end of the resistor R6 are connected to the reference ground of the controller M1.

Specifically, the voltage preset value set by the controller M1 is variable, there are a first voltage preset value and a second voltage preset value, the first voltage preset value is higher than the second voltage preset value, when the switching power supply device is started under the condition that the input voltage is lower than the first voltage preset value, the voltage preset value of the controller M1 is the first voltage preset value, when the input voltage rises to be higher than the first voltage preset value in the working process of the switching power supply device, the voltage preset value is correspondingly switched from the first voltage preset value to the second voltage preset value, when the switching power supply device is started under the condition that the input voltage is higher than the first voltage preset value, the voltage preset value is the second voltage preset value, and when the input voltage falls to be lower than the second voltage preset value in the working process of the switching power supply device, the voltage preset value is correspondingly switched from the second voltage preset value to the first voltage preset value.

Preferably, the switch S1 is a switching device.

Preferably, the DCDC unit is a flyback converter, the flyback converter includes an auxiliary winding, a different-name end of the auxiliary winding is connected to the power supply end V1 of the controller M1 for supplying power to the controller M1, and a same-name end of the auxiliary winding is connected to the voltage detection end V2 of the controller M1 for enabling the controller M1 to detect the input voltage of the switching power supply device.

The detailed working principle of the present invention will be described later with reference to specific embodiments, which are not described herein, and compared with the prior art, the present invention has the following beneficial effects:

1. by utilizing the characteristic of capacitive energy storage, the filtering unit is improved into a low-voltage large-capacity capacitor and a high-voltage small-capacity capacitor for combined use, so that the quantity and cost of the filtering capacitors during the wide input voltage application of the ACDC switching power supply are effectively reduced, and the product volume is reduced;

2. the low-voltage high-capacity capacitor in the filtering unit is connected with the inductor and the switch in series, the switch is controlled according to the bus voltage and the switch current to realize the switching of the low-voltage high-capacity capacitor, the impact current when the low-voltage high-capacity capacitor is put into the filtering unit is effectively reduced, the impact current of a diode in the rectifying unit of the ACDC switching power supply is further reduced, and the cost of the rectifying unit can be reduced;

3. the filtering unit is beneficial to the auxiliary winding of the transformer of the DCDC unit to obtain power supply and detect bus voltage, and the detection circuit has low cost and high efficiency;

4. the utility model is applied to the wide-input ACDC switching power supply, and has smaller volume and higher economic practicability.

Drawings

Fig. 1 is a block diagram of a conventional ACDC switching power supply;

FIG. 2 is a block diagram of an application circuit of a switching power supply apparatus according to the present invention;

FIG. 3 is a partial circuit block diagram of the first embodiment of the present invention;

FIG. 4 is a partial circuit block diagram of a second embodiment of the present invention.

Detailed Description

FIG. 2 is a schematic circuit diagram of a switching power supply device, which is applied to a switching power supply and includes a filtering unit and a DCDC unit, and has a positive input terminal Vin +, a negative input terminal Vin-, a positive output terminal Vo +, and a negative output terminal Vo-. The filtering unit comprises a capacitor C1, a switch S1, an inductor L, a diode D1, a diode D2, a capacitor C2 with withstand voltage smaller than that of the capacitor C1 and a controller M1; the embodiment of the utility model is explained by taking a DCDC unit as a flyback converter, the DCDC unit in the technical scheme of the utility model has various conditions, and the DCDC unit in the embodiment of the utility model comprises a transformer T, a switch S2, a diode D3, a capacitor C3, a capacitor C4, a diode D4 and a controller M2; the transformer T includes three windings, a primary winding NP, a secondary winding NS, and an auxiliary winding NA.

The positive pole of a capacitor C1 is connected with a positive pole input end Vin +, the negative pole of a capacitor C1 is connected with a negative pole input end Vin-, the positive pole of a capacitor C2 is connected with a positive pole input end Vin +, the negative pole of a capacitor C2 is connected with the cathode of a diode D2 and one end of an inductor L, the anode of a diode D2 is connected with a negative pole input end Vin-, the other end of the inductor L is connected with the anode of a diode D1 and the drain of a switch S1, the cathode of a diode D1 is connected with a positive pole input end Vin +, the source of a switch S1 is connected with a negative pole input end Vin-and a current sampling end V3 of a controller M1, the current sampling end V3 of a controller M1 detects the source current of a switch S1, the gate of the switch S1 is connected with a driving output end V4 of a controller M1, a power supply end V1 of the controller M1 is connected with a different-name end of an auxiliary winding NA of a transformer T in a DCDC unit, a voltage detection end V24 of a controller M1 is connected with a same-name terminal of the DCDC unit, the ground reference GND of the controller M1 is connected to the negative input Vin-.

The dotted terminal of the primary winding NP is connected with the positive input terminal Vin +, the synonym terminal of the primary winding NP is connected with the drain of the switch S2, the dotted terminal of the auxiliary winding NA is connected with the cathode of the diode D4, the synonym terminal of the auxiliary winding NA is connected with the positive terminal of the capacitor C4 and the power supply terminal V5 of the controller M2, the negative stage of the capacitor C4 is connected with the negative input terminal Vin-, the anode of the diode D4 is connected with the negative stage of the capacitor C4, the source of the switch S2 is connected with the negative input terminal Vin-, the controller M2 current sampling terminal V7, the grid of the switch S2 is connected with the driving output terminal V6 of the controller M2, the anode of the diode D3 is connected with the synonym terminal of the secondary winding NS, the cathode of the diode D3 is connected with the positive terminal Vo +, the anode of the capacitor C3 is connected with the positive output terminal Vo +, the cathode of the capacitor C3 is connected with the dotted terminal of the negative output terminal Vo-, the secondary winding NS, the voltage detection end V8 of the controller M2 is connected with the positive output end Vo +, the primary side reference ground GND1 of the controller M2 is connected with the negative input end Vin-, and the secondary side reference ground GND2 of the controller M2 is connected with the negative output end Vo-.

The DCDC unit is a flyback converter, and the working principle of the DCDC unit is as follows: when the input voltage Vin is applied to the input end of the switching power supply device, the controller M2 periodically compares the feedback value of the output voltage Vo with the current peak value of the switch S2 under the action of the clock to generate a periodic driving signal, so as to realize that the driving switch S2 works in a periodic on/off mode (referred to as a switching mode for short), thereby realizing output voltage stabilization and overcurrent protection; it should be noted that the supply terminal V5 of the controller M2 is also connected to a start-up supply circuit taken from the positive input terminal Vin + of the switching power supply device, which supplies power to the controller M2 only during the start-up of the flyback converter, and which is used by the supply bypass of the auxiliary winding NA of the transformer T when the output voltage Vo of the flyback converter is established, and which is not shown in fig. 2, considering that a person skilled in the art would understand it; according to the transformer relation, when the switch S2 is switched on, the potential of the same-name end of the primary winding NP of the transformer T is the input positive voltage Vin + of the switching power supply device, and the auxiliary winding NA of the transformer T and the primary winding NP have the turn ratio relation, so that the voltage of the same-name end of the auxiliary winding NA is reflected to be in proportion to the Vin +, and the input voltage of the switching power supply device is detected by utilizing the characteristic; in addition, the potential of the different-name terminal of the auxiliary winding NA and the output voltage Vo of the switching power supply device have a turn ratio relationship, so that the different-name terminal of the auxiliary winding NA can be used for supplying power to the controller M1 and the controller M2.

First embodiment

Fig. 3 is a schematic circuit diagram of a controller M1 of a filter unit in a switching power supply device according to the present invention, and the principle of the branch where the auxiliary winding NA in the DCDC unit connected to the filter unit is located is described in fig. 2 and the foregoing, where only understanding is needed: the voltage signal output by the dotted terminal of the auxiliary winding NA is proportional to the input positive voltage Vin + of the switching power supply device during the conduction period of the switch S2, and the voltage signal output by the dotted terminal of the auxiliary winding NA is proportional to the output positive voltage Vo +.

In fig. 3, the filter unit controller M1 includes a diode D5, a capacitor C5, a resistor R1, a resistor R2, a resistor R3, a zener diode D6, a voltage regulator K, and a logic processing module. The anode of the diode D5 is used as a voltage detection terminal V2 of the controller M1, the cathode of the diode D5 is connected with one end of a resistor R1 and the anode of a capacitor C5, the other end of the resistor R1 is connected with one end of a resistor R2 and the sampling terminal of a voltage regulator K, the output terminal of the voltage regulator K is connected with one end of a resistor R3, the cathode of a zener diode D6 and a logic processing module, the logic processing module further has an input terminal which is used as a current sampling terminal V3 of the controller M1, the logic processing module further includes an output terminal which is used as a driving output terminal V4 of the controller M1, the other end of the resistor R3 is used as a power supply terminal V1 of the controller M1, the cathode of the capacitor C5, the other end of the resistor R2, the reference ground of the voltage regulator K and the anode of the zener diode D6, and the connection point is used as a reference ground GND with the controller M1.

The logic processing module has two input signals which are respectively input by the output end of the voltage stabilizing source K and the source electrode of the switch S1.

The working principle of the present embodiment is explained below with reference to fig. 2 and 3:

the present embodiment is a switching power supply device, which is applied to an ACDC switching power supply with a wide input voltage range, and the preceding stage of the switching power supply device is usually a rectifying unit formed by diodes, when an ac voltage is input into the rectifying unit, a pulsating dc voltage is generated at the input terminal Vin +, Vin-of the switching power supply device in this embodiment, when the voltage is within a range allowed by the operation of the DCDC unit, the DCDC unit is started, and in the starting process of the DCDC unit, the switch S2 operates in a switching mode at a certain frequency. During the starting process of the DCDC unit, when the switch S2 is closed, the filter unit controller M1 detects a voltage capable of reflecting an input positive voltage Vin + through the voltage sampling terminal V2 connected to the same-name terminal of the auxiliary winding of the DCDC unit, and the voltage charges the capacitor C5 through the diode D5; when the switch S2 is turned off, the capacitor C5 maintains the voltage value at the turn-off time of the switch S2, and the voltage value of the capacitor C5 reflects the input positive voltage Vin + of the switching power supply apparatus when the switch S2 is turned on, and since the switching frequency of the switch S2 is much higher than the variation frequency of the input positive voltage Vin +, the voltage value of the capacitor C5 can be approximately considered to reflect the input positive voltage Vin + in real time. The voltage of the different-name terminal of the auxiliary winding NA of the DCDC unit is in a turn ratio relation with the positive voltage Vo + output by the DCDC unit, and the positive voltage Vo + output by the DCDC unit slowly rises in the starting process, so that the voltage of the different-name terminal of the auxiliary winding NA also slowly rises; the sampling end of a voltage stabilizing source K in the filtering unit samples the voltage at two ends of a capacitor C5 through resistors R1 and R2, namely samples the input positive voltage Vin + of the switch power supply device, and the preset voltage value can be set by adjusting the resistor ratio of R1 to R2; when the input voltage Vin + is greater than the preset voltage value, the output end signal of the voltage-stabilizing source K is a low-voltage signal (for example, if a voltage-stabilizing source with the K of 1.25V is selected, when the voltage of the K sampling end is higher than 1.25V, the voltage of the K output end is 1.25V); when the input voltage Vin + is smaller than the preset voltage value, the signal of the output end of the regulator voltage source K is the regulated voltage value of the regulator diode D6, and the regulated voltage value of the regulator diode D6 can be usually selected to be higher than the reference voltage of the regulator voltage source K (if D6 is selected to be a 5.1V regulator tube, the output end of K at this time is at 5.1V level); therefore, the present embodiment samples the input voltage by sampling the voltage of the auxiliary winding NA, and the controller M1 obtains a low level signal when the input voltage is higher than the preset voltage value, and the controller M1 obtains a high level signal when the input voltage is lower than the preset voltage value.

The controller M1 also samples the current signal of the switch S1, and thus, according to the logic processing module of the controller M1, such functions can be realized: when the input voltage is higher than the preset voltage value, the controller M1 outputs a low level signal, the control switch S1 is in an off state, and the filter unit only works independently through the capacitor C1; when the input voltage is lower than the preset voltage value and the current sampling value is smaller than the preset current value, the controller M1 outputs a high-level signal, the switch S1 is controlled to be in a conducting state, and the filtering unit capacitor C1 and the capacitor C2 work in parallel; when the input voltage is lower than the preset voltage value and the current sampling value is larger than the preset current value, the controller M1 outputs a low level signal, the control switch S1 is in an off state, and the filtering unit only has the capacitor C1 to work alone.

Therefore, the embodiment realizes that the filtering unit of the switching power supply device has a capacitor with larger capacity to work when the input voltage is lower, and the filtering unit of the switching power supply device has a capacitor with smaller capacity to work when the input voltage is higher, so that the high-voltage small-capacity capacitor and the low-voltage large-capacity capacitor are fully utilized, the total capacitance quantity is reduced, and the size and the cost are reduced.

Second embodiment

Fig. 4 is a schematic circuit diagram of a controller M1 of a filter unit of a switching power supply apparatus according to another embodiment of the present invention, in which the circuit has a variable voltage preset value. This embodiment is different from the first embodiment in that: the voltage stabilizing circuit further comprises a voltage stabilizing diode D7, a resistor R5, a resistor R6 and a triode T1, wherein the cathode of the voltage stabilizing diode D7 is connected with the output end of a voltage stabilizing source K, one end of the resistor R5 is connected with the sampling end of the voltage stabilizing source K, the emitter of the triode T1 is connected with the other end of the resistor R5, the base of the triode T1 is connected with the anode of the voltage stabilizing diode D7 and one end of the resistor R6, and the collector of the triode T1 and the other end of the resistor R6 are connected with the reference ground of the controller M1.

The working principle of the present embodiment is basically the same as that of the first embodiment, except that the added devices bring about the following effects:

when the switching power supply device is powered on, and the DCDC unit is started, the triode T1 is conducted, the resistor R5 is connected with the resistor R2 in parallel and then divided by the resistor R1, and at the moment, the voltage preset value of the controller M1 is determined by the voltage division ratio of the equivalent resistor and the resistor R1 after the resistors R5 and R2 are connected in parallel and is counted as a first voltage preset value; when the input voltage is higher than the first voltage preset value, the output end of the voltage-stabilizing source K is at a low level, the triode T1 is turned off at the moment, the resistor R5 is not connected with the resistor R2 in parallel, and the voltage preset value of the controller M1 is determined by the voltage division ratio of the resistor R5 and the resistor R2 and is counted as a second voltage preset value; according to the principle of resistance voltage division, the first voltage preset value is higher than the second voltage preset value.

The variable voltage preset value has the advantages that: the input voltage Vin of the switching power supply device is a pulsating direct-current voltage, and when there is only one voltage preset value, when the input voltage Vin fluctuates around the voltage preset value, the filtering unit switch S1 is frequently turned on and off, so that the low-voltage capacitor C2 is frequently switched when the switching power supply device works at the voltage preset value, and the system efficiency of the working point is not high. When the controller M1 adopts two voltage preset values, since the first voltage preset value is higher than the second voltage preset value, when the switching power supply device is started under the condition of low-voltage input (the input voltage is lower than the first voltage preset value), the voltage preset value of the controller M1 is the first voltage preset value, when the input voltage rises to be higher than the first voltage preset value in the working process of the switching power supply device, the voltage preset value is correspondingly switched from the first voltage preset value to the second voltage preset value, when the switching power supply device is started under the condition of high-voltage input (the input voltage is higher than the first voltage preset value), the voltage preset value is the second voltage preset value, and when the input voltage drops to be lower than the second voltage preset value in the working process of the switching power supply device, the voltage preset value is correspondingly switched from the second voltage preset value to the first voltage preset value. Therefore, in actual work, when the input voltage is higher than the first voltage preset value, the switch S1 is turned off, and when the input voltage is lower than the second voltage preset value, the switch S1 is turned on, so that the situation that the low-voltage capacitor C2 is frequently switched at the voltage preset value is avoided, and the system efficiency and the stability at the voltage preset value are improved.

The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be construed as limiting the present invention, and it will be apparent to those skilled in the art that several modifications and decorations can be made, such as changing one inductor and one low voltage capacitor in the filtering unit in the present embodiment into a plurality of inductors and a plurality of capacitors, without departing from the spirit and scope of the present invention; the voltage preset values of the filter unit controller in the embodiment are increased from one to a plurality; current sampling in the embodiment is replaced by resistance sampling from mutual inductor sampling; in the embodiment, a flyback converter of the DCDC unit rectified by a diode is replaced by a flyback converter of synchronous rectification; the DCDC unit in this embodiment is replaced by an ordinary flyback converter with an active clamp flyback converter, and these improvements and modifications should also be regarded as the protection scope of the present invention, which should not be repeated herein by using the embodiments, and the protection scope of the present invention should be subject to the scope defined by the claims.

Claims (10)

1. The utility model provides a switching power supply device, is applied to switching power supply, includes filtering unit and DCDC unit, contains positive input terminal Vin +, negative input terminal Vin-, positive output Vo + and negative output Vo-, its characterized in that:

the filter unit is connected with the positive input end Vin + and the negative input end Vin-, and is also connected with the DCDC unit, the DCDC unit is connected with the positive output end Vo + and the negative output end Vo-, the filter unit is used for sampling voltage and current, setting a voltage preset value and a current preset value, comparing the sampled voltage and current with corresponding preset values respectively, and adjusting the size of a capacitor for filtering of the access circuit in real time;

the filter unit comprises a capacitor C1, a switch S1, an inductor L, a diode D1, a diode D2, a capacitor C2 and a controller M1, wherein the withstand voltage of the capacitor C2 is different from that of a capacitor C1, the anode of a capacitor C1 is connected with an anode input terminal Vin +, the cathode of a capacitor C1 is connected with a cathode input terminal Vin-, the anode of a capacitor C2 is connected with the anode input terminal Vin +, the cathode of a capacitor C2 is connected with the cathode of a diode D2 and one end of the inductor L, the anode of a diode D2 is connected with the cathode input terminal Vin-, the other end of the inductor L is connected with the anode of a diode D1 and the drain of a switch S1, the cathode of a diode D1 is connected with the anode input terminal Vin +, the source of a switch S1 is connected with the cathode input terminal Vin-and a current sampling terminal V3 of the controller M1, a current sampling terminal V3 of a controller M1 detects the source current of the switch S1, the gate of the switch S1 is connected with a driving output terminal V4 of the controller M1, a power supply end V1 of the controller M1 is connected with the DCDC unit, a voltage detection end V2 of the controller M1 is connected with the DCDC unit and used for detecting the output voltage of the switching power supply device, and a reference ground GND of the controller M1 is connected with a negative electrode input end Vin < - >;

the DCDC unit is used for realizing stable direct-current voltage output and supplying the stable direct-current voltage output to a load at the rear stage of the switching power supply device.

2. The switching power supply device according to claim 1, wherein: the capacitor C1 is a small-capacity capacitor with withstand voltage meeting the highest input voltage of the switching power supply device, and the capacitor C2 is a large-capacity capacitor with withstand voltage lower than that of the capacitor C1.

3. The switching power supply device according to claim 1, wherein: the voltage preset value is variable.

4. The switching power supply device according to claim 1, wherein: the controller M1 comprises a diode D5, a capacitor C5, a resistor R1, a resistor R2, a resistor R3, a voltage stabilizing diode D6, a voltage stabilizing source K and a logic processing module; the anode of the diode D5 is used as a voltage detection terminal V2 of the controller M1, the cathode of the diode D5 is connected with one end of a resistor R1 and the anode of a capacitor C5, the other end of the resistor R1 is connected with one end of a resistor R2 and the sampling terminal of a voltage regulator K, the output terminal of the voltage regulator K is connected with one end of a resistor R3, the cathode of a zener diode D6 and a logic processing module, the logic processing module further has an input terminal which is used as a current sampling terminal V3 of the controller M1, the logic processing module further includes an output terminal which is used as a driving output terminal V4 of the controller M1, the other end of the resistor R3 is used as a power supply terminal V1 of the controller M1, the cathode of the capacitor C5, the other end of the resistor R2, the reference ground of the voltage regulator K and the anode of the zener diode D6, and the connection point is used as a reference ground GND with the controller M1.

5. The switching power supply device according to claim 4, wherein: the logic processing module has two input signals which are respectively input by the output end of a voltage stabilizing source K and the source electrode of a switch S1.

6. The switching power supply device according to claim 4, wherein: the filter unit has the specific functions that the current of the switch S1 and the input voltage of the switching power supply device are detected, a voltage preset value is set according to the withstand voltage value of the capacitor C2, a current preset value is set according to the current specification of the switch S1, when the input voltage is higher than the voltage preset value, the controller M1 controls the switch S1 to be in an off state, when the input voltage is lower than the voltage preset value and the current of the switch S1 is smaller than the current preset value, the controller M1 controls the switch S1 to be in an on or high-frequency switching state, and when the input voltage is lower than the voltage preset value and the current sampling value of the switch S1 is larger than the current preset value, the controller M1 controls the switch S1 to be in the off state.

7. The switching power supply device according to claim 4, wherein: the voltage stabilizing circuit further comprises a voltage stabilizing diode D7, a resistor R5, a resistor R6 and a triode T1, wherein the cathode of the voltage stabilizing diode D7 is connected with the output end of a voltage stabilizing source K, one end of the resistor R5 is connected with the sampling end of the voltage stabilizing source K, the emitter of the triode T1 is connected with the other end of the resistor R5, the base of the triode T1 is connected with the anode of the voltage stabilizing diode D7 and one end of the resistor R6, and the collector of the triode T1 and the other end of the resistor R6 are connected with the reference ground of the controller M1.

8. The switching power supply device according to claim 7, wherein: the voltage preset value set by the controller M1 is variable, and has a first voltage preset value and a second voltage preset value, where the first voltage preset value is higher than the second voltage preset value, when the switching power supply device is started under the condition that the input voltage is lower than the first voltage preset value, the voltage preset value of the controller M1 is the first voltage preset value, when the input voltage rises to be higher than the first voltage preset value in the working process of the switching power supply device, the voltage preset value is correspondingly switched from the first voltage preset value to the second voltage preset value, when the input voltage is higher than the first voltage preset value, the voltage preset value is the second voltage preset value, and when the input voltage drops to be lower than the second voltage preset value in the working process of the switching power supply device, the voltage preset value is correspondingly switched from the second voltage preset value to the first voltage preset value.

9. The switching power supply device according to any one of claims 1 to 8, characterized in that: the switch S1 is a switching device.

10. The switching power supply device according to claim 1, 4 or 7, wherein: the DCDC unit is a flyback converter which comprises an auxiliary winding, the different name end of the auxiliary winding is connected with a power supply end V1 of the controller M1 and used for supplying power to the controller M1, and the same name end of the auxiliary winding is connected with a voltage detection end V2 of the controller M1 and used for enabling the controller M1 to detect the input voltage of the switching power supply device.

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