A switching power supply with ultra-wide input voltage range

Abstract

The present invention discloses an ultra-wide voltage input switching power supply input multi-tube series flyback equalizing circuit, which includes a primary circuit, a secondary circuit, and n transformers connected in series. Each of the transformers includes m primary windings and one secondary winding. The primary circuit includes {(m-1)*n+1} first capacitors connected in series and {(m-1)*n+1} switching tubes. On the basis of the existing input multi-tube series flyback circuit, by paralleling the primary windings of different transformers and making the turn ratios of the input windings and output windings of each stage of the transformer consistent. The use of multiple transformers connected in series has the advantage of broadening the input voltage on the basis of the existing low-voltage MOS tube material platform. Selecting and paralleling the primary windings of different transformers can enhance the coupling between multiple transformers.

Description

Technical Field

[0001] This invention patent relates to the field of switching power supplies, and is particularly applicable to switching power supplies with ultra-wide and ultra-high input voltages. Background Art

[0002] Currently, as a new generation of DC transmission technology, flexible DC transmission uses turn-off devices (usually IGBTs) and high-frequency modulation technology, and can independently control the output active power and reactive power to achieve precise compensation. The compensation of the output active power and reactive power is achieved by alternately turning on the IGBTs in the H-bridge to control the angle between the voltage and current of the power grid. With the continuous improvement of the withstand voltage value of the IGBT group (H-bridge) (from the initial withstand voltage of several hundred volts to the current withstand voltage of several thousand volts), the requirements for the input range of switching power supply products have gradually increased. Currently, there is still a gap in switching power supplies with ultra-wide input ranges in the industry, and using a multi-module input series circuit has reliability risks such as complex control and poor dynamic performance. Therefore, it is necessary to accelerate the R & D investment in this area.

[0003] For a switching power supply with an ultra-wide input range, the commonly adopted solution at present is to connect the input circuits in series to meet the requirement of high-voltage withstand. However, due to the limitation of the number of transformer windings and the coupling performance difference of transformers, the input circuits cannot be infinitely connected in series. At this time, a circuit form of multiple transformers and multiple input modules connected in series appears, such as the utility model circuit with the application number 201821557890.6. This series flyback converter, as Figure 5 shown in the schematic diagram of this utility model, detects the inputs of multiple modules, samples and compares the voltage equalization effect of each module through an operational amplifier, and appropriately reduces or increases the duty cycle of different modules to achieve input voltage equalization and output current sharing of the product. However, the disadvantages of this circuit are as follows: for two different control circuits, the control effect of the loop is poor, and loop oscillation may occur under dynamic conditions, resulting in unstable output, or even causing imbalance and damage phenomena, and the reliability risk of the product is relatively high.

[0004] In a series circuit, if the voltage is not evenly distributed and the withstand voltage value borne by a certain input circuit is higher than the withstand voltage value of its own device, it will damage the entire switching power supply system, thus causing more serious consequences. Therefore, the voltage equalization of the series input circuit is a particularly important point that needs to be considered for this circuit.

[0005] The Chinese patent document with the publication number CN112072926A provides a prior art for solving the voltage equalization problem of ultra-high voltage input switching power supplies. Please refer to Figure 6 , the input circuit solution is: multi-stage series connection, the turn ratio of the input winding and the output winding of the transformer in each stage of the input circuit is the same, and the switching tubes in each stage of the input circuit are turned on simultaneously. This solution realizes that the input voltages of each stage of the switching power supply can be evenly divided without any detection circuit.

[0006] However, the technology provided in this patent document has significant limitations. Due to topological reasons, the turns ratio of the primary and secondary sides usually takes a relatively large value, and the number of turns of the secondary winding is small. Relying solely on the parallel connection of the secondary windings to equalize the voltage reflected to the primary winding will have significant limitations. Moreover, since the position of the secondary winding in the transformer structure is relatively fixed and cannot be flexibly changed, the coupling performance will also be affected, resulting in the possibility that the primary winding may not be evenly pressurized under high-voltage input during operation, causing a certain unit to exceed the withstand voltage value and resulting in the phenomenon of product explosion. Summary of the Invention

[0007] The present invention aims to overcome at least one of the above-mentioned defects in the prior art and provides a switch-mode power supply with ultra-wide input voltage range. By paralleling any primary winding except the first one of the previous transformer with the first primary winding of the next transformer, the coupling between the transformers is enhanced, thereby increasing the reliability of the switch-mode power supply product.

[0008] The technical solution provided by the present invention is as follows:

[0009] In a first aspect, a switch-mode power supply with ultra-wide input voltage range is provided, which includes a primary circuit, a secondary circuit, and n transformers connected in series. Each transformer includes m primary windings and one secondary winding;

[0010] The primary circuit includes {(m - 1)*n + 1} first capacitors connected in series and {(m - 1)*n + 1} switching tubes;

[0011] The same-name end of the x-th primary winding of the first transformer is connected to the same-name end of the first primary winding of the second transformer, and the opposite-name end of the x-th primary winding of the first transformer is connected to the opposite-name end of the first primary winding of the second transformer;

[0012] The same-name end of the x-th primary winding of the previous transformer is connected to the same-name end of the first primary winding of the next transformer, and the opposite-name end of the x-th primary winding of the previous transformer is connected to the opposite-name end of the first primary winding of the next transformer;

[0013] The same-named ends of the 1st, 2nd, ..., (x-1)th, (x+1)th, ..., mth primary windings of the previous (n-1) transformers are respectively connected to the first end of the first capacitor, and the opposite-named ends are respectively connected to the first end of the switching tube. The second end of the first capacitor is connected to the second end of the switching tube. Moreover, the same-named end of one primary winding corresponds to the first end of one first capacitor, the opposite-named end of one primary winding corresponds to the first end of one switching tube, and the second end of one first capacitor corresponds to the second end of one switching tube;

[0014] The same-named ends of all the primary windings of the last transformer are connected to the first end of the first capacitor, and the opposite-named ends are respectively connected to the first end of the switching tube. The second end of the first capacitor is connected to the second end of the switching tube. Moreover, the same-named end of one primary winding corresponds to the first end of one first capacitor, the opposite-named end of one primary winding corresponds to the first end of one switching tube, and the second end of one first capacitor corresponds to the second end of one switching tube;

[0015] After the same-named end of the first primary winding of the first transformer is connected to the first end of one first capacitor, it serves as the positive input terminal of the switching power supply;

[0016] After the second end of the last first capacitor is connected to the second end of the last switching tube, it is grounded, and both the first capacitor and the switching tube are connected to the last primary winding of the last transformer;

[0017] Wherein, n, m, and x are all natural numbers greater than or equal to 2, and x ≤ m;

[0018] The secondary windings are connected in series and then connected in series with the secondary circuit. Moreover, the first output terminal of the secondary circuit serves as the positive output terminal of the switching power supply, and the second output terminal serves as the negative output terminal of the switching power supply;

[0019] Each transformer and the first capacitor, the switching tube, and the secondary circuit connected thereto form a sub-switching power supply, and the sub-switching power supplies are connected in series.

[0020] Preferably, the number of turns of all the primary windings is the same, and the number of turns of all the secondary windings is the same.

[0021] Preferably, all the switching tubes are turned on or off simultaneously.

[0022] In a second aspect, a switching power supply with ultra-wide voltage input is provided, which includes a primary circuit, a secondary circuit, and n transformers connected in series. Each transformer includes m primary windings and one secondary winding;

[0023] The primary side circuit includes \((m - 1)\times n+1\) serially connected first capacitors and \((m - 1)\times n+1\) switching tubes;

[0024] The same-named terminal of the \(x\)th primary winding of the first transformer is connected to the same-named terminal of the first primary winding of the second transformer, and the different-named terminal of the \(x\)th primary winding of the first transformer is connected to the different-named terminal of the first primary winding of the second transformer;

[0025] The same-named terminal of the \(x\)th primary winding of the previous transformer is connected to the same-named terminal of the first primary winding of the next transformer, and the different-named terminal of the \(x\)th primary winding of the previous transformer is connected to the different-named terminal of the first primary winding of the next transformer;

[0026] The same-named terminals of the 1st, 2nd, \(\cdots\), \((x - 1)\)th, \((x + 1)\)th, \(\cdots\), \(m\)th primary windings of the previous \((n - 1)\) transformers are respectively connected to the first end of the first capacitor, and the different-named terminals are respectively connected to the first end of the switching tube. The second end of the first capacitor is connected to the second end of the switching tube, and the same-named terminal of a primary winding is correspondingly connected to the first end of a first capacitor, the different-named terminal of a primary winding is correspondingly connected to the first end of a switching tube, and the second end of a first capacitor is correspondingly connected to the second end of a switching tube;

[0027] The same-named terminals of all the primary windings of the last transformer are connected to the first end of the first capacitor, and the different-named terminals are respectively connected to the first end of the switching tube. The second end of the first capacitor is connected to the second end of the switching tube, and the same-named terminal of a primary winding is correspondingly connected to the first end of a first capacitor, the different-named terminal of a primary winding is correspondingly connected to the first end of a switching tube, and the second end of a first capacitor is correspondingly connected to the second end of a switching tube;

[0028] After the same-named terminal of the first primary winding of the first transformer is connected to the first end of a first capacitor, it serves as the positive input terminal of the switching power supply;

[0029] After the second end of the last first capacitor is connected to the second end of the last switching tube, it is grounded, and both the first capacitor and the switching tube are connected to the last primary winding of the last transformer;

[0030] Wherein, \(n\), \(m\), and \(x\) are all natural numbers greater than or equal to 2, and \(x\leq m\);

[0031] The secondary side circuit includes \(m\) rectification circuits and a second capacitor;

[0032] The non - same - name terminals of each of the secondary windings are connected to the input terminal of a rectification circuit. After the output terminal of the rectification circuit is connected to the first terminal of the second capacitor, it serves as the positive output terminal of the switching power supply;

[0033] The same - name terminals of each of the secondary windings are connected to the second terminal of the second capacitor and serve as the negative output terminal of the switching power supply;

[0034] Each of the transformers and the first capacitor, the switching transistor, and the secondary circuit connected thereto form a sub - switching power supply, and the sub - switching power supplies are connected in series;

[0035] Wherein, both n and m are natural numbers greater than or equal to 2.

[0036] Preferably, the number of turns of all the primary windings is the same, and the number of turns of all the secondary windings is the same.

[0037] Preferably, all the switching transistors are turned on or off simultaneously.

[0038] Preferably, all the switching transistors are controlled by the same control chip.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] 1. In the present invention, by arranging multiple primary windings in each transformer, and connecting any one of the primary windings except the first one in the previous transformer in parallel with the first primary winding in the subsequent transformer, the two parallel - connected primary windings are equivalent to one primary winding participating in the operation of the main power circuit of the switching power supply, so as to enhance the coupling performance between the transformers and further improve the voltage equalization degree of each cascade sub - switching power supply during transient start - up and steady state.

[0041] 2. The present invention does not need to add any voltage equalization detection circuit. Only by ensuring that the turns ratio of all the primary windings to the corresponding secondary windings is the same, automatic voltage equalization can be achieved.

[0042] 3. The number of series - connected transformers and the number of primary windings in each transformer can be infinitely expanded and increased, so as to achieve the effect of broadening the input voltage and making its application scenarios more extensive.

[0043] 4. The timing of all the switching transistors is to turn on and off simultaneously. The control method is simple and can be realized only by controlling multiple switching transistors through a single control chip, further simplifying the ultra - wide - voltage - input switching power supply circuit of the present invention and being easy to implement. Brief Description of the Drawings

[0044] Figure 1 It is the circuit diagram of the switching power supply of the first embodiment;

[0045] Figure 2 Circuit diagram of the switching power supply for the second embodiment;

[0046] Figure 3 Circuit diagram of the switching power supply for the third embodiment;

[0047] Figure 4 Circuit diagram of the switching power supply for the fourth embodiment;

[0048] Figure 5 Existing technical solution of the input cascade equalizing voltage circuit;

[0049] Figure 6 Schematic diagram of the existing ultra-wide voltage input switching power supply. Specific embodiments

[0050] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. The described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0051] In the prior art, a circuit form of multiple transformers and multiple input modules connected in series is adopted to meet the requirements of high-voltage withstand and voltage equalization. It is necessary to detect multiple input modules and use different control circuits to control them, resulting in poor control effects of different loops. Under dynamic conditions, loop oscillation may occur, the output is unstable, and even misalignment and damage phenomena may occur, and the product reliability risk is relatively large; moreover, the coupling performance between transformers is poor, resulting in poor stability of the product.

[0052] To solve the above technical problems, the present application sets multiple series-connected transformers. Each transformer has multiple primary windings. The last primary winding of the previous transformer is connected in parallel with the first primary winding of the next transformer, so that the two parallel primary windings are equivalent to one primary winding, and this equivalent primary winding participates in the main power circuit of the circuit, and the rest of the primary windings all participate in the work of the main power circuit. The present application increases the coupling performance between transformers by connecting the primary windings in parallel, further improving the voltage equalization degree of each cascade sub-switching power supply during transient startup and steady state. The number of transformers and the number of primary windings can be set according to the input voltage requirements of different products, expanding the application range of the switching power supply.

[0053] In one embodiment, an ultra-wide voltage input switching power supply is provided, which includes a primary circuit, a secondary circuit, and n series-connected transformers. Each of the transformers includes m primary windings and one secondary winding;

[0054] The primary side circuit includes \((m - 1)\times n+1\) serially connected first capacitors and \((m - 1)\times n+1\) switching tubes;

[0055] The same-named terminal of the \(x\)th primary winding of the first transformer is connected to the same-named terminal of the first primary winding of the second transformer, and the different-named terminal of the \(x\)th primary winding of the first transformer is connected to the different-named terminal of the first primary winding of the second transformer;

[0056] The same-named terminal of the \(x\)th primary winding of the previous transformer is connected to the same-named terminal of the first primary winding of the next transformer, and the different-named terminal of the \(x\)th primary winding of the previous transformer is connected to the different-named terminal of the first primary winding of the next transformer;

[0057] The same-named terminals of the 1st, 2nd, \(\cdots\), \((x - 1)\)th, \((x + 1)\)th, \(\cdots\), \(m\)th primary windings of the previous \((n - 1)\) transformers are respectively connected to the first end of the first capacitor, and the different-named terminals are respectively connected to the first end of the switching tube. The second end of the first capacitor is connected to the second end of the switching tube, and the same-named terminal of one primary winding is correspondingly connected to the first end of one first capacitor, the different-named terminal of one primary winding is correspondingly connected to the first end of one switching tube, and the second end of one first capacitor is correspondingly connected to the second end of one switching tube;

[0058] The same-named terminals of all the primary windings of the last transformer are connected to the first end of the first capacitor, and the different-named terminals are respectively connected to the first end of the switching tube. The second end of the first capacitor is connected to the second end of the switching tube, and the same-named terminal of one primary winding is correspondingly connected to the first end of one first capacitor, the different-named terminal of one primary winding is correspondingly connected to the first end of one switching tube, and the second end of one first capacitor is correspondingly connected to the second end of one switching tube;

[0059] After the same-named terminal of the first primary winding of the first transformer is connected to the first end of a first capacitor, it serves as the positive input terminal of the switching power supply;

[0060] After the second end of the last first capacitor is connected to the second end of the last switching tube, it is grounded, and both the first capacitor and the switching tube are connected to the last primary winding of the last transformer;

[0061] Wherein, \(n\), \(m\), and \(x\) are all natural numbers greater than or equal to 2, and \(x\leq m\);

[0062] The secondary windings are connected in series and then connected in series with the secondary circuit. The first output terminal of the secondary circuit serves as the positive output terminal of the switching power supply, and the second output terminal serves as the negative output terminal of the switching power supply;

[0063] Each of the transformers, the first capacitor connected thereto, the switching transistor, and the secondary circuit form a sub-switching power supply, and the sub-switching power supplies are connected in series. In this embodiment, by providing multiple primary windings in each transformer, and connecting any one of the primary windings except the first one in the previous transformer in parallel with the first primary winding in the subsequent transformer, the two parallel primary windings are equivalent to one primary winding participating in the operation of the main power circuit of the switching power supply, so that the coupling performance between the transformers can be enhanced, and the voltage sharing degree of each cascaded sub-switching power supply during transient startup and steady state can be further improved.

[0064] In another embodiment, an ultra-wide voltage input switching power supply includes a primary circuit, a secondary circuit, and n transformers connected in series. Each of the transformers includes m primary windings and one secondary winding;

[0065] The primary circuit includes {(m - 1)*n + 1} first capacitors connected in series and {(m - 1)*n + 1} switching transistors;

[0066] The same-named end of the x-th primary winding of the first transformer is connected to the same-named end of the first primary winding of the second transformer, and the different-named end of the x-th primary winding of the first transformer is connected to the different-named end of the first primary winding of the second transformer;

[0067] The same-named end of the x-th primary winding of the previous transformer is connected to the same-named end of the first primary winding of the subsequent transformer, and the different-named end of the x-th primary winding of the previous transformer is connected to the different-named end of the first primary winding of the subsequent transformer;

[0068] The same-named ends of the 1st, 2nd,... (x - 1)-th, (x + 1)-th,... m-th primary windings of the previous (n - 1) transformers are respectively connected to the first ends of the first capacitors, and the different-named ends are respectively connected to the first ends of the switching transistors. The second ends of the first capacitors are connected to the second ends of the switching transistors, and the same-named end of one primary winding is correspondingly connected to the first end of one first capacitor, the different-named end of one primary winding is correspondingly connected to the first end of one switching transistor, and the second end of one first capacitor is correspondingly connected to the second end of one switching transistor;

[0069] The corresponding ends of the primary windings of all the last transformers are connected to the first end of the first capacitor, and the opposite ends are respectively connected to the first ends of the switching transistors. The second end of the first capacitor is connected to the second end of the switching transistor, and the corresponding end of one primary winding is connected to the first end of one first capacitor, the opposite end of one primary winding is connected to the first end of one switching transistor, and the second end of one first capacitor is connected to the second end of one switching transistor;

[0070] After the corresponding end of the first primary winding of the first transformer is connected to the first end of a first capacitor, it serves as the positive input terminal of the switching power supply;

[0071] After the second end of the last first capacitor is connected to the second end of the last switching transistor, it is grounded, and both the first capacitor and the switching transistor are connected to the last primary winding of the last transformer;

[0072] Wherein, n, m, and x are all natural numbers greater than or equal to 2, and x ≤ m;

[0073] The secondary circuit includes m rectifying circuits and a second capacitor;

[0074] The opposite end of each secondary winding is connected to the input end of a rectifying circuit. After the output end of the rectifying circuit is connected to the first end of the second capacitor, it serves as the positive output terminal of the switching power supply;

[0075] The corresponding end of each secondary winding is connected to the second end of the second capacitor and serves as the negative output terminal of the switching power supply;

[0076] Each transformer and the first capacitor, the switching transistor, and the secondary circuit connected thereto form a sub-switching power supply, and the sub-switching power supplies are connected in series. In this embodiment, by arranging a plurality of primary windings in each transformer, and connecting any one of the primary windings except the first one in the previous transformer in parallel with the first primary winding in the next transformer, the two parallel primary windings are equivalent to one primary winding participating in the operation of the main power circuit of the switching power supply, so as to enhance the coupling performance between the transformers and further improve the voltage sharing degree of each cascade sub-switching power supply during transient starting and steady state.

[0077] In order to make the primary windings of each sub-switching power supply evenly divide the input voltage and achieve the purpose of voltage sharing, the number of turns of all the primary windings is the same, and the number of turns of all the secondary windings is the same.

[0078] In one embodiment, all the switching transistors are turned on or off simultaneously, aiming to ensure that the input voltage of the switching power supply is equal to the voltage of the primary winding of the transformer during operation, so that voltage sharing can be automatically achieved at the input end.

[0079] To simplify the circuit of the switching power supply described in this embodiment and make it easier to implement, all the switching tubes are controlled by the same control chip.

[0080] Specifically, the switching tubes described in this embodiment can be metal-oxide-semiconductor transistors (MOSFETs), or other types of electronically controlled switching devices, such as bipolar junction transistors (BJTs) and insulated-gate bipolar transistors (IGBTs). This embodiment does not limit the type of switching tube used.

[0081] Specifically, the rectifier circuit in the secondary circuit can use rectifier diodes or synchronous rectifier tubes, which is not limited here;

[0082] Specifically, any primary winding of the first (n - 1) transformers can be selected to be connected in parallel with the first primary winding of the next transformer. The positions of the primary windings in each transformer that are connected to the first primary winding of the next transformer can be different or the same. In the specific implementation process, the last winding of the first (n - 1) transformers is selected to be connected in parallel with the first primary winding of the next transformer.

[0083] First Embodiment

[0084] In this embodiment, taking n = 2, x = m = 2, the secondary windings are connected in series and then connected in series with the secondary circuit, and the switching tube is a MOS tube as an example. Among them, the first end of the switching tube is the drain, and the second end is the source;

[0085] As Figure 1 shown, it is the specific circuit diagram of the switching power supply described in this embodiment, and its specific connection method is as follows:

[0086] The switching power supply includes three first capacitors, three switching tubes, and two transformers. Each transformer includes two primary windings and one secondary winding. Among them, the three first capacitors are capacitor C1, capacitor C2, and capacitor C3 respectively. The first end of the first capacitor is the positive electrode, and the second end is the negative electrode. The three switching tubes are switching tube Q1, switching tube Q2, and switching tube Q3 respectively. The two transformers are transformer T1 and transformer T2 respectively. The two primary windings and one secondary winding of transformer T1 are primary winding P11, primary winding P12, and secondary winding S1 respectively. The two primary windings and one secondary winding of transformer T2 are primary winding P21, primary winding P22, and secondary winding S2 respectively. The secondary circuit includes diode D1 and second capacitor Co;

[0087] Specifically, the positive electrode of the capacitor C1 is connected to the same-named end of the primary winding P11 of the transformer T1, serving as the positive input terminal Vin+ of the switching power supply. The negative electrode is connected to the source electrode of the switching transistor Q1, the same-named end of the primary winding P12 of the transformer T1, the same-named end of the primary winding P21 of the transformer T2, and the positive electrode of the capacitor C2. The drain electrode of the switching transistor is connected to the opposite-named end of the primary winding P11 of the transformer T1; the negative electrode of the capacitor C2 is connected to the source electrode of the switching transistor Q2, the same-named end of the primary winding P22 of the transformer T2, and the positive electrode of the capacitor C3. The drain electrode of the switching transistor Q2 is connected to the opposite-named end of the primary winding P12 of the transformer T1 and the opposite-named end of the primary winding P21 of the transformer T2. After the negative electrode of the capacitor C2 is connected to the source electrode of the switching transistor Q3, it is grounded, and the drain electrode of the switching transistor Q3 is connected to the opposite-named end of the primary winding P22 of the transformer T2. The opposite-named end of the secondary winding S1 of the transformer T1 is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the output terminal VOUT+ and the positive electrode of the output capacitor Co. The same-named end of the first secondary winding S1 of the first transformer T1 is connected to the opposite-named end of the secondary winding S2 of the transformer T2. The same-named end of the secondary winding S2 of the transformer T2 is connected to the negative electrode of the second capacitor Co and serves as the negative output terminal VOUT- of the switching power supply.

[0088] The number of turns of the primary winding of the transformer T1 and the turns ratio of the primary and secondary windings are the same as those of the primary winding of the transformer T2 and the turns ratio of the primary and secondary windings, and are described as 2:2:1 in this embodiment.

[0089] The working principle of the circuit in this embodiment is as follows:

[0090] When the switching transistors Q1, Q2, and Q3 in the primary circuit are simultaneously turned on (since the driving signals of the control chip are floatingly driven through the isolation driving transformer, the signals of the three transistors are almost synchronous), the capacitors C1, C2, and C3 are magnetized and store energy respectively through the three equivalent windings of the primary windings P11, P12 in parallel with the primary winding P21, and the primary winding P22. When the switching transistors Q1, Q2, and Q3 are simultaneously turned off, the energy is released through the secondary winding S1 of the transformer T1 and the secondary winding S2 of the transformer T2, and the energy is supplied to the output terminal and stored in the second capacitor Co at the same time.

[0091] When each switching tube is turned on, the voltages of the primary windings P11, P12 (or primary winding P21) and the primary winding P22 are Vin / 3 respectively. Since the turns ratios of the primary and secondary sides of the two transformers are both 2:1 and the secondary windings are connected in series, the voltage across the second capacitor Co is Vin / 3. Since the turns ratios of the primary and secondary windings of the two transformers are P11:P12:S1 = 2:2:1 and P21:P22:S2 = 2:2:1 respectively, and the primary windings P12 and P21 are connected in parallel, the three windings of the primary windings P11, P12 (primary winding P21), and P22 are evenly voltage-divided. The two transformers enhance the coupling through the parallel-connected primary windings. It only needs to ensure that the switching tubes are turned on and off simultaneously, that is, each primary winding can automatically maintain an evenly voltage-divided state.

[0092] Second Embodiment

[0093] Different from the first embodiment, in this embodiment, the secondary circuit includes two rectification circuits and a second capacitor Co;

[0094] The non - same - name ends of each of the secondary windings are connected to the input end of a rectification circuit. After the output end of the rectification circuit is connected to the first end of the second capacitor Co, it serves as the positive output end of the switching power supply;

[0095] The same - name ends of each of the secondary windings are connected to the second end of the second capacitor Co and serve as the negative output end of the switching power supply.

[0096] In this embodiment, taking the use of diodes as the rectification circuits as an example for illustration, where the two rectification circuits are diode D1 and diode D1 respectively; as Figure 2 shown, it is the circuit schematic diagram of the switching power supply of this embodiment. The connection method of its primary circuit and each primary winding of each transformer is the same as that of the first embodiment. The difference is that the secondary windings S1 and S2 are not connected in a series form, but each stores energy in the second capacitor Co and provides energy to the output terminals after being rectified by diodes; the specific connection relationship between the secondary windings S1, S2 and the secondary circuit is as follows:

[0097] The non - same - name end of the secondary winding S1 is connected to the anode of the diode D1, the same - name end of the secondary winding S1 is connected to the negative electrode of the second capacitor Co, and the cathode of the diode D1 is connected to the positive electrode of the second capacitor Co and then serves as the positive output end VOUT+ of the switching power supply; the non - same - name end of the secondary winding S2 is connected to the anode of the diode D2, the same - name end of the secondary winding S2 is connected to the negative electrode of the second capacitor Co, and the cathode of the diode D2 is connected to the positive electrode of the second capacitor Co; the negative electrode of the second capacitor serves as the negative output end VOUT - of the switching power supply.

[0098] The working principle of the circuit of this embodiment is:

[0099] When the switching transistors Q1, Q2, and Q3 of the primary circuit are conducting simultaneously (since the drive signals of the control chip are floatingly driven through the isolation drive transformer, the signals of the three transistors are almost synchronous), capacitors C1, C2, and C3 are magnetized and store energy respectively through the primary windings P11, P12, and in parallel with the primary windings P21 and P22, which are three equivalent windings. When the switching transistors Q1, Q2, and Q3 are turned off simultaneously, the energy is released through the secondary windings S1 of transformer T1 and the secondary winding S2 of transformer T2, and the energy is supplied to the output terminal, and at the same time, it is stored in the second capacitor Co.

[0100] When each switching transistor is conducting, the voltages of the primary windings P11, P12 (or P21) and P22 are Vin / 3 respectively. Since the turns ratios of the primary and secondary sides of the two transformers are both 2:1, and the secondary windings are in series, the voltage on the second capacitor Co is Vin / 3. Since the turns ratios of the primary and secondary windings of the two transformers are P11:P12:S1 = 2:2:1 and P21:P22:S2 = 2:2:1 respectively, and the primary windings P12 and P21 are in parallel, the three windings of the primary windings P11, P12 (P21), and P22 are voltage-equalized. The two transformers enhance the coupling through the parallel primary windings. It only needs to ensure that the switching transistors are turned on and off simultaneously, that is, each primary winding can automatically maintain the voltage-equalized state.

[0101] The third embodiment

[0102] In this embodiment, taking x = m = 2, the secondary windings are in series and then in series with the secondary circuit, and the switching transistor is a MOS transistor as an example for illustration. Among them, the first end of the switching transistor is the drain, and the second end is the source;

[0103] As Figure 3 shown, it is the specific circuit diagram of the switching power supply described in this embodiment. In this embodiment, the switching power supply includes n transformers, n + 1 first capacitors, and n + 1 switching transistors. The primary windings of multiple transformers are in series, and there are only two primary windings in the primary side of all transformers. The specific connection method is as follows:

[0104] For the switching power supply, the n transformers are transformer T1, transformer T2, ..., transformer Tn respectively. The two primary windings and one secondary winding of transformer T1 are primary winding P11, primary winding P12 and secondary winding S1 respectively. Similarly, the two primary windings and one secondary winding of transformer Tn are primary winding Pn1, primary winding Pn2 and secondary winding Sn respectively; the n + 1 first capacitors are capacitor C1, capacitor C1, ..., capacitor Cn+1 respectively, and the n + 1 switching tubes are switching tube Q1, switching tube Q2, ..., switching tube Qn+1 respectively; the secondary circuit includes diode D1 and second capacitor Co;

[0105] Specifically, the positive electrode of capacitor C1 is connected to the same-named end of the primary winding P11 of transformer T1, serving as the input terminal Vin+ of the switching power supply. The negative electrode is connected to the source of switching tube Q1, the same-named end of the primary winding P12 of transformer T1, the same-named end of the primary winding P21 of transformer T2 and the positive electrode of capacitor C2. The drain of switching tube Q1 is connected to the different-named end of the first primary winding P11 of transformer T1; the negative electrode of capacitor C2 is connected to the source of switching tube Q3, the same-named end of the primary winding P22 of transformer T2, the same-named end of the primary winding P31 of transformer T3 and the positive electrode of capacitor C2. Similarly, the same-named end of the primary winding Pn1 of transformer Tn (n > 2) and the positive electrode of capacitor Cn, and the drain of switching tube Qn-1 are connected; the different-named end of the primary winding P12 of transformer T1 is connected to the different-named end of the primary winding P21 of transformer T2. The negative electrode of capacitor Cn is connected to the source of switching tube Qn and the same-named end of the primary winding Pn2 of transformer Tn, the positive electrode of capacitor Cn+1. The drain of switching tube Qn is connected to the different-named end of the primary winding P(n-1)2 of transformer Tn-1 and the different-named end of the primary winding Pn1 of transformer Tn; the negative electrode of capacitor Cn+1 is grounded after being connected to the source of switching tube Qn+1, and the drain of switching tube Qn+1 is connected to the different-named end of the primary winding Pn2 of transformer Tn. The different-named end of the secondary winding S1 of transformer T1 is connected to the anode of diode D1. The cathode of diode D1 is connected to the positive electrode of the second capacitor Co and then serves as the positive output terminal VOUT+ of the switching power supply. The same-named end of the secondary winding S1 of transformer T1 is connected to the different-named end of the secondary winding S2 of transformer T2. The same-named end of the secondary winding S2 of transformer T2 is connected to the different-named end of the secondary winding Sn of transformer Tn. After the same-named end of the secondary winding Sn of transformer Tn is connected to the negative electrode of the second capacitor Co, it serves as the negative output terminal VOUT- of the switching power supply.

[0106] Its specific principle is similar to that of the first embodiment and will not be elaborated here.

[0107] Using this method for series connection of the primary sides of the transformers, theoretically, the input voltage range can be infinitely broadened, and each winding has a good voltage sharing effect.

[0108] Fourth Embodiment

[0109] In this embodiment, taking x = m = 3, n = 2, the secondary windings are connected in series and then connected in series with the secondary circuit, and the switching transistor is a MOS transistor as an example for illustration. Among them, the first end of the switching transistor is the drain, and the second end is the source;

[0110] As Figure 4 shown, it is the specific circuit diagram of the switching power supply described in this embodiment. In this embodiment, the switching power supply includes two transformers, seven first capacitors and seven switching transistors. The primary windings of the two transformers are connected in series. Each transformer primary consists of six primary windings. The secondary circuit includes diode D1 and second capacitor Co; the specific connection method is as follows:

[0111] For the switching power supply, the two transformers are transformer T1 and transformer T2 respectively. The six primary windings and one secondary winding of transformer T1 are primary winding P11, primary winding P12,..., primary winding P16 and secondary winding S1 respectively. Similarly, the six primary windings and one secondary winding of transformer T2 are primary winding P21, primary winding P22,..., primary winding P26 and secondary winding S2 respectively; the 7 first capacitors are capacitor C1, capacitor C1,..., capacitor C7 respectively, and the 7 switching transistors are switching transistor Q1, switching transistor Q2,..., switching transistor Q7 respectively;

[0112] The positive electrode of the capacitor C1 is connected to the same-named terminal of the primary winding P11 of the transformer T1, serving as the input terminal Vin+ of the switching power supply. The negative electrode of the capacitor C1 is connected to the source electrode of the switching transistor Q1, the same-named terminal of the primary winding P12 of the transformer T1, and the positive electrode of the capacitor C2. The drain electrode of the switching transistor Q1 is connected to the different-named terminal of the primary winding P11 of the transformer T1. The negative electrode of the capacitor C2 is connected to the source electrode of the switching transistor Q2, the same-named terminal of the primary winding P13 of the transformer T1, the same-named terminal of the primary winding P21 of the transformer T2, and the positive electrode of the capacitor C3. The drain electrode of the switching transistor Q2 is connected to the different-named terminal of the primary winding P12 of the transformer T1. The negative electrode of the capacitor C3 is connected to the source electrode of the switching transistor Q3, the same-named terminal of the primary winding P22 of the transformer T2, and the positive electrode of the capacitor C4. The drain electrode of the switching transistor Q3 is connected to the different-named terminal of the primary winding P13 of the transformer T3 and the different-named terminal of the primary winding P21 of the transformer T2. And so on, the negative electrode of the (2m - 2)th energy storage capacitor C2m - 2 is connected to the source electrode of the switching transistor Q2m - 2, the same-named terminal of the primary winding P2m of the transformer T2, and the positive electrode of the capacitor C2m - 1. The drain electrode of the switching transistor Q2m - 1 is connected to the different-named terminal of the second primary winding P2(2m - 2) of the transformer T2. The negative electrode of the capacitor C2m - 1 is connected to the source electrode of the switching transistor Q2m - 1 and the ground of the primary side. The drain electrode of the switching transistor Q2m - 1 is connected to the different-named terminal of the primary winding P2m of the transformer T2. The different-named terminal of the secondary winding S1 of the transformer T1 is connected to the anode of the diode D1. The cathode of the diode D1 is connected to the positive electrode of the second capacitor Co, serving as the positive output terminal VOUT+ of the switching power supply. The same-named terminal of the secondary winding S1 of the transformer T1 is connected to the different-named terminal of the secondary winding S2 of the transformer T2. After the same-named terminal of the first secondary winding S2 of the transformer T2 is connected to the negative electrode of the second capacitor Co, it serves as the negative output terminal VOUT- of the switching power supply.

[0113] The specific principle is similar to that of the first embodiment and will not be elaborated here.

[0114] By connecting the primary sides of the transformers in series in this way, theoretically, the input voltage range can be infinitely broadened, and each winding has a good voltage equalization effect.

[0115] The above are only the implementation manners of the present invention. It should be particularly noted that the above implementation manners should not be regarded as limitations on the present invention. For those of ordinary skill in the art, without departing from the spirit and scope of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A switching power supply with ultra-wide input voltage range, characterized in that It includes a primary circuit, a secondary circuit, and n transformers connected in series. Each of the transformers includes m primary windings and one secondary winding; The primary circuit includes {(m - 1)*n + 1} capacitors connected in series and {(m - 1)*n + 1} switching tubes; The homonymous ends of the x-th primary winding of the first transformer are connected to the homonymous ends of the first primary winding of the second transformer, and the non-homonymous ends of the x-th primary winding of the first transformer are connected to the non-homonymous ends of the first primary winding of the second transformer; The homonymous ends of the x-th primary winding of the previous transformer are connected to the homonymous ends of the first primary winding of the next transformer, and the non-homonymous ends of the x-th primary winding of the previous transformer are connected to the non-homonymous ends of the first primary winding of the next transformer; The homonymous ends of the 1st, 2nd,... (x - 1)-th, (x + 1)-th,... m-th primary windings of the previous (n - 1) transformers are respectively connected to the first ends of the first capacitors, and the non-homonymous ends are respectively connected to the first ends of the switching tubes. The second ends of the first capacitors are connected to the second ends of the switching tubes, and the homonymous end of one primary winding is correspondingly connected to the first end of one first capacitor, the non-homonymous end of one primary winding is correspondingly connected to the first end of one switching tube, and the second end of one first capacitor is correspondingly connected to the second end of one switching tube; The homonymous ends of all the primary windings of the last transformer are connected to the first ends of the first capacitors, and the non-homonymous ends are respectively connected to the first ends of the switching tubes. The second ends of the first capacitors are connected to the second ends of the switching tubes, and the homonymous end of one primary winding is correspondingly connected to the first end of one first capacitor, the non-homonymous end of one primary winding is correspondingly connected to the first end of one switching tube, and the second end of one first capacitor is correspondingly connected to the second end of one switching tube; After the homonymous ends of the first primary winding of the first transformer are connected to the first end of a first capacitor, it serves as the positive input terminal of the switching power supply; After the second ends of the last first capacitor and the second ends of the last switching tube are connected to ground, and both the first capacitor and the switching tube are connected to the last primary winding of the last transformer; Wherein, n, m, and x are all natural numbers greater than or equal to 2, and x ≤ m; The secondary windings are connected in series and then connected in series with the secondary circuit. The first output terminal of the secondary circuit serves as the positive output terminal of the switching power supply, and the second output terminal serves as the negative output terminal of the switching power supply; Each transformer and the first capacitor, the switching tube, and the secondary circuit connected thereto form a sub-switching power supply, and the sub-switching power supplies are connected in series.

2. The ultra-wide voltage input switching power supply according to claim 1, wherein The number of turns of all the primary windings is the same, and the number of turns of all the secondary windings is the same.

3. The ultra-wide voltage input switching power supply according to claim 1, wherein All the switching tubes conduct or turn off simultaneously.

4. The ultra-wide voltage input switching power supply according to claim 3, wherein All the switching tubes are controlled by the same control chip.

5. A switching power supply with ultra-wide input voltage range, characterized in that, It includes a primary circuit, a secondary circuit, and n transformers connected in series. Each of the transformers includes m primary windings and one secondary winding; The primary circuit includes {(m - 1)*n + 1} first capacitors connected in series and {(m - 1)*n + 1} switching tubes; The same-name end of the x-th primary winding of the first transformer is connected to the same-name end of the first primary winding of the second transformer, and the opposite-name end of the x-th primary winding of the first transformer is connected to the opposite-name end of the first primary winding of the second transformer; The same-name end of the x-th primary winding of the previous transformer is connected to the same-name end of the first primary winding of the next transformer, and the opposite-name end of the x-th primary winding of the previous transformer is connected to the opposite-name end of the first primary winding of the next transformer; The same-name ends of the 1st, 2nd,... (x - 1)-th, (x + 1)-th,... m-th primary windings of the previous (n - 1) transformers are respectively connected to the first ends of the first capacitors, and the opposite-name ends are respectively connected to the first ends of the switching tubes. The second ends of the first capacitors are connected to the second ends of the switching tubes. Moreover, the same-name end of one primary winding is correspondingly connected to the first end of one first capacitor, the opposite-name end of one primary winding is correspondingly connected to the first end of one switching tube, and the second end of one first capacitor is correspondingly connected to the second end of one switching tube; The same-name ends of all the primary windings of the last transformer are connected to the first ends of the first capacitors, and the opposite-name ends are respectively connected to the first ends of the switching tubes. The second ends of the first capacitors are connected to the second ends of the switching tubes. Moreover, the same-name end of one primary winding is correspondingly connected to the first end of one first capacitor, the opposite-name end of one primary winding is correspondingly connected to the first end of one switching tube, and the second end of one first capacitor is correspondingly connected to the second end of one switching tube; After the same-name end of the first primary winding of the first transformer is connected to the first end of one first capacitor, it serves as the positive input terminal of the switching power supply; After the second end of the last first capacitor is connected to the second end of the last switching tube, it is grounded, and both the first capacitor and the switching tube are connected to the last primary winding of the last transformer; Wherein, n, m, and x are all natural numbers greater than or equal to 2, and x ≤ m; The secondary circuit includes m rectifier circuits and a second capacitor; The opposite-name end of each secondary winding is connected to the input end of one rectifier circuit. After the output end of the rectifier circuit is connected to the first end of the second capacitor, it serves as the positive output terminal of the switching power supply; The same-name end of each secondary winding is connected to the second end of the second capacitor and serves as the negative output terminal of the switching power supply; Each transformer and the first capacitor, the switching tube, and the secondary circuit connected thereto form a sub-switching power supply, and the sub-switching power supplies are connected in series.

6. The ultra-wide voltage input switching power supply according to claim 5, characterized in that, The number of turns of all the primary windings is the same, and the number of turns of all the secondary windings is the same.

7. The ultra-wide input voltage switching power supply according to claim 5, wherein All of the switching tubes are turned on or off simultaneously.

8. The ultra-wide voltage input switching power supply according to claim 7, characterized in that, All of the switching tubes are controlled by the same control chip.

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