Isolated voltage gain adjustable DC-DC converter

Abstract

The utility model provides an isolation type voltage gain adjustable DC-DC converter. The isolation type voltage gain adjustable DC-DC converter comprises a DC source uin, a full-bridge converter, a three-winding transformer T, two auxiliary capacitors CP1 and CP2, two auxiliary diodes DP1 and DP2, and 2n expansion units. According to the utility model, the output voltage of the circuit can be effectively improved, and the defects caused by the adoption of a high transformer turn ratio for realizing large voltage gain are avoided. The expansion structure is simple and is only composed of two capacitors and two diodes, the structure does not contain magnetic elements, and the cost and the size of the converter can be effectively reduced. And different numbers of expansion units can be adopted according to specific application occasions, high boost of the converter is realized, and the voltage gain is adjustable, so that different boost requirements are realized, and the applicability of the circuit is effectively expanded.

Description

Technical Field

[0001] The utility model relates to a power electronic converter, in particular to an isolated voltage gain adjustable DC-DC converter. Background Art

[0002] At present, photovoltaic power generation and energy storage batteries are widely used in the power industry. However, due to the low output voltage level of the DC power supply of the above new energy power generation methods and the high grid-connected voltage, the voltage gain of traditional DC-DC converters is difficult to meet the high step-up requirements. Therefore, a high-gain DC-DC converter is needed to convert the low voltage of the new energy power supply into the high voltage required for grid connection.

[0003] In order to improve the voltage gain, for example, the patent with the application publication number CN111884521A discloses a single-stage Boost full-bridge boost zero-current-switching DC converter and its control method. The primary side of the converter consists of a boost inductor, an LC series resonance cavity, and a full-bridge module. Two switching tubes in the lagging leg of the full-bridge module are respectively connected in series with a diode in the forward direction to prevent reverse current flow. The secondary side is a voltage-doubling rectifier circuit, and the primary and secondary sides are connected through a high-frequency transformer. The converter adopts fixed-frequency phase-shifted PWM control. The two switching tubes in the leading leg are driven with the same duty cycle greater than 0.5, and the phase difference is half a switching period. The duty cycles of the two switching tubes in the lagging leg are both 0.5, and the phase difference is half a switching period. There is a phase-shift angle between the drives of the switching tubes on the diagonal of the two legs. The duty cycle of the leading leg drive and the phase-shift angle satisfy a fixed relationship, and the transmission power and the boost ratio can be adjusted by controlling the phase-shift angle. The utility model can achieve zero-current turn-on and turn-off of all semiconductor devices. However, the design scheme of this converter is complex, and accurate calculation of the device parameters in the resonance cavity is required. At the same time, its structure is not expandable, the voltage gain is relatively fixed, and it is difficult to meet the high step-up requirements in different scenarios. Summary of the Utility Model

[0004] To solve the technical problems such as the low voltage gain, insufficient boost capacity, and small adjustable range of voltage gain of traditional DC-DC converters. The utility model provides an isolated voltage gain adjustable DC-DC converter, which can effectively improve the voltage gain and has multi-stage gain adjustment ability.

[0005] To achieve the above object, the technical solution adopted by the utility model is:

[0006] An isolated voltage gain adjustable DC-DC converter, characterized in that: the converter includes a DC source u in , a full-bridge converter, a three-winding transformer T, two auxiliary capacitors C P1 , C P2 , two auxiliary diodes DP1 , D P2 , 2n extended units, where n is a natural number and the value range is n≥1;

[0007] The full-bridge converter includes 4 switches S1, S2, S3, S4, and the primary winding T of the three-winding transformer T P ; Its connection form is as follows:

[0008] The upper end of the DC source u in is connected to the drain of the switch S1 and the drain of the first switch S1. The lower end of the DC source u in is connected to the source of the third switch S3 and the source of the fourth switch S4. The source of the first switch S1 is connected to the drain of the third switch S3 and the A end of the primary winding T of the three-winding transformer T P , and the source of the second switch S2 is connected to the drain of the fourth switch S4 and the B end of the primary winding T of the three-winding transformer T P . The gates of the 4 switches S1, S2, S3, S4 are respectively connected to their respective controllers. The first switch S1 and the fourth switch S4 are synchronously controlled, and the second switch S2 and the third switch S3 are synchronously controlled. The duty cycle is maintained at 0.5 and they conduct alternately;

[0009] The three-winding transformer T includes the primary winding T P , the secondary winding T S1 and the secondary winding T S2 . The left end of the first auxiliary capacitor C P1 is connected to the D end of the secondary winding T of the three-winding transformer T S1 . The right end of the first auxiliary capacitor C P1 is connected to the anode of the first auxiliary diode D P1 . The cathode of the first auxiliary diode D P1 is connected to the C end of the secondary winding T of the three-winding transformer T S1 . The left end of the second auxiliary capacitor C P2 is connected to the D' end of the secondary winding T of the three-winding transformer T S2 . The right end of the second auxiliary capacitor C P2 is connected to the anode of the second auxiliary diode D P2 . The cathode of the second auxiliary diode D P2 is connected to the C' end of the secondary winding T of the three-winding transformer T S2 ;

[0010] Each extended unit has the same structure and includes a left capacitor, a right capacitor, an upper diode, and a lower diode. Its connection form is as follows:

[0011] When n = 1, the left capacitor C of the first extended unit 12The left end is connected to the C terminal of the secondary winding of the three-winding transformer T, and the left capacitor C 12 The right end is connected to the upper diode D 11 The anode of and the lower diode D 12 The cathode is connected, and the anode of the lower diode D 12 Is connected to the D terminal of the secondary winding of the three-winding transformer T, and the right capacitor C 11 The upper end is connected to the cathode of the upper diode D 11 The cathode is connected, and the lower end of the right capacitor C 11 Is connected to the anode of the lower diode D 12 To form the first expansion unit; The left capacitor C of the second expansion unit 22 The left end is connected to the C` terminal of the secondary winding of the three-winding transformer T, and the left capacitor C 22 The right end is connected to the upper diode D 21 The anode of and the lower diode D 22 The cathode is connected, and the anode of the lower diode D 22 Is connected to the D` terminal of the secondary winding of the three-winding transformer T, and the right capacitor C 21 The upper end is connected to the cathode of the upper diode D 21 The cathode is connected, and the lower end of the right capacitor C 21 Is connected to the anode of the lower diode D 22 To form the second expansion unit;

[0012] When n>1, among the 2n expansion units, the 2n-1th expansion unit includes the left capacitor C (2n-1)2 And the right capacitor C (2n-1)1 The upper diode D (2n-1)1 The lower diode D (2n-1)2 ; Among them, the left capacitor C of the 2n-1th expansion unit (2n-1)2 The left end is connected to the C terminal of the secondary winding of the three-winding transformer T, and the left capacitor C (2n-1)2 The right end is connected to the anode of the upper diode D (2n-1)1 And the cathode of the lower diode D (2n-1)2 The cathode is connected, and the anode of the lower diode D (2n-1)2 Is connected to the cathode of the upper diode D of the 2n-3th expansion unit (2n-3)1 The right capacitor C (2n-1)1 The upper end is connected to the cathode of the upper diode D (2n-1)1 The cathode is connected, and the lower end of the right capacitor C (2n-1)1 Is connected to the anode of the lower diode D (2n-1)2 Among the 2n expansion units, the 2nth expansion unit includes the left capacitor C (2n)2 And the right capacitor C (2n)1 The upper diode D (2n)1 The lower diode D (2n)2; among them, the left capacitor C of the 2nth expansion unit (2n)2 has its left end connected to the C' end of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C (2n)2 is connected to the anode of the upper diode D (2n)1 and the cathode of the lower diode D (2n)2 . The anode of the lower diode D (2n)2 is connected to the cathode of the upper diode D 2(n-1)1 of the 2(n - 1)th expansion unit. The upper end of the right capacitor C (2n)1 is connected to the cathode of the upper diode D (2n)1 and the right end of the first auxiliary capacitor C P1 . The lower end of the right capacitor C (2n)1 is connected to the anode of the lower diode D (2n)2 ;

[0013] Both ends of the load R are respectively connected to the upper end of the capacitor C (2n-1)1 in the 2n - 1th expansion unit and the right end of the second auxiliary capacitor C P2 .

[0014] When using 4 expansion units and the first switch S1 and the second switch S4 are turned on, the upper diodes D 11 of the first expansion unit, the upper diodes D 21 of the second expansion unit, the upper diodes D 31 of the third expansion unit, and the upper diodes D 41 of the fourth expansion unit are turned on. The first auxiliary diode D P1 , the second auxiliary D P2 , and the lower diodes D 12 of the first expansion unit, the lower D 22 of the second expansion unit, the lower D 32 of the third expansion unit, and the lower D 42 of the fourth expansion unit are turned off. The two auxiliary capacitors C P1 , C P2 , and the right capacitors C 11 of the first expansion unit, the right capacitors C 21 of the second expansion unit, the right capacitors C 31 of the third expansion unit, and the right capacitors C 41 of the fourth expansion unit are charged. The AC input source u s discharges with the left capacitors C 12 of the first expansion unit, the left capacitors C 22 of the second expansion unit, the left capacitors C 32 of the third expansion unit, and the left capacitors C 42 of the fourth expansion unit to supply power to the load.

[0015] When 4 expansion units are adopted and the second switch S2 and the third switch S3 are turned on, the upper diodes D of the first expansion unit 11 , the upper diodes D of the second expansion unit 21 , the upper diodes D of the third expansion unit 31 , the upper diodes D of the fourth expansion unit 41 are turned off, and the first auxiliary diode D P1 , the second auxiliary D P2 and the lower diodes D of the first expansion unit 12 , the lower D of the second expansion unit 22 , the lower D of the third expansion unit 32 , the lower D of the fourth expansion unit 42 are turned on. The AC input source u s discharges with two auxiliary capacitors C P1 , C P2 and the right capacitors C of the first expansion unit 11 , the right capacitors C of the second expansion unit 21 , the right capacitors C of the third expansion unit 31 , the right capacitors C of the fourth expansion unit 41 to supply power to the load, and the left capacitors C of the first expansion unit 12 , the left capacitors C of the second expansion unit 22 , the left capacitors C of the third expansion unit 32 , the left capacitors C of the fourth expansion unit 42 are charged.

[0016] The output voltage of the isolated voltage gain adjustable DC-DC converter of the present utility model is adjusted by adjusting the number of expansion units, achieving high-gain multi-stage voltage regulation ability. The voltage gain that each expansion unit can increase is 2, and the input-output voltage gain of the rectifier circuit is N1(2n + 1)+N2(2n + 1). Wherein, N1 is the turns ratio of the secondary winding T S1 of the three-winding transformer to the primary winding T P , and N2 is the turns ratio of the secondary winding T S2 of the three-winding transformer to the primary winding T P .

[0017] An isolated voltage gain adjustable DC-DC converter of the present utility model has the following technical effects:

[0018] 1) It can effectively increase the output voltage of the circuit, avoiding the drawbacks brought by using a high transformer turns ratio to achieve a large voltage gain.

[0019] 2) The expansion unit in the present utility model has a simple structure and few components. While increasing the voltage gain of the converter, it avoids complex structures and high costs.

[0020] 3) According to specific application scenarios, the present utility model can adopt different numbers of expansion units to achieve high voltage boost of the converter, and the voltage gain is adjustable, so as to meet different boost requirements and effectively expand the applicability of the circuit. Description of the Drawings

[0021] The present utility model will be further described below in conjunction with the drawings and embodiments:

[0022] Figure 1 is the specific circuit schematic diagram of the present utility model with 4 expansion units.

[0023] Figure 2 is the specific circuit schematic diagram of the present utility model with n expansion units.

[0024] Figure 3 is the input-output voltage simulation diagram of the present utility model with 4 expansion units when the input voltage is 100V and N1 = N2 = 1. Detailed Embodiment

[0025] Figure 1 The shown isolated voltage-gain adjustable DC-DC converter includes a DC source u in , a full-bridge converter, a three-winding transformer T, 2 auxiliary capacitors C P1 、C P2 , 2 auxiliary diodes D P1 、D P2 , and 4 expansion units; their connection forms are as follows:

[0026] The full-bridge converter includes switches S1, S2, S3, S4, the primary winding T of the transformer T P , the upper end of the DC source u in is connected to the drain of switch S1 and the drain of switch S1, the lower end of the DC source u in is connected to the source of switch S3 and the source of switch S4, the source of switch S1 is connected to the drain of switch S3 and the A end of the primary winding T of the three-winding transformer T P , the source of switch S2 is connected to the drain of switch S4 and the B end of the primary winding T of the three-winding transformer T P , the gates of switches S1, S2, S3, S4 are respectively connected to their respective controllers, switches S1 and S4 are synchronously controlled, switches S2 and S3 are synchronously controlled, the duty cycle is maintained at 0.5, and they conduct alternately;

[0027] The three-winding transformer T includes a primary winding T P, the secondary winding T S1 and the secondary winding T S2 , the first auxiliary capacitor C P1 The left end of is connected to the D terminal of the secondary winding T of the three-winding transformer T S1 , the first auxiliary capacitor C P1 The right end of is connected to the anode of the first auxiliary diode D P1 , the first auxiliary diode D P1 The cathode of is connected to the C terminal of the secondary winding T of the three-winding transformer T S1 , the second auxiliary capacitor C P2 The left end of is connected to the D' terminal of the secondary winding T of the three-winding transformer T S2 , the second auxiliary capacitor C P2 The right end of is connected to the anode of the second auxiliary diode D P2 , the second auxiliary diode D P2 The cathode of is connected to the C' terminal of the secondary winding T of the three-winding transformer T S2 .

[0028] The first expansion unit includes the left capacitor C 12 , the right capacitor C 11 , the upper diode D 11 , the lower diode D 12 ; among them, the left end of the left capacitor C of the first expansion unit 12 is connected to the C terminal of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C 12 is connected to the anode of the upper diode D 11 and the cathode of the lower diode D 12 , the anode of the lower diode D 12 is connected to the D terminal of the secondary winding of the three-winding transformer T, and the upper end of the right capacitor C 11 is connected to the cathode of the upper diode D 11 , and the lower end of the right capacitor C 11 is connected to the anode of the lower diode D 12 , forming the first expansion unit.

[0029] The second expansion unit includes the left capacitor C 22 , the right capacitor C 21 , the upper diode D 21 , the lower diode D 22 ; among them, the left end of the left capacitor C of the second expansion unit 22 is connected to the C' terminal of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C 22 is connected to the anode of the upper diode D 21 and the cathode of the lower diode D 22 , the anode of the lower diode D 22The anode is connected to the D' end of the secondary winding of the three-winding transformer T, and the upper end of the right capacitor C 21 is connected to the cathode of the upper diode D 21 The upper end of the right capacitor C 21 is connected to the anode of the lower diode D 22 to form the second expansion unit.

[0030] The third expansion unit includes the left capacitor C 32 , the right capacitor C 31 , the upper diode D 31 , the lower diode D 32 ; among them, the left end of the left capacitor C 32 in the third expansion unit is connected to the C end of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C 32 is connected to the anode of the upper diode D 31 and the cathode of the lower diode D 32 , the anode of the lower diode D 32 is connected to the cathode of the upper diode D 11 in the first expansion unit, and the lower end of the right capacitor C 11 is connected to the anode of the lower diode D 12 to form the third expansion unit.

[0031] The fourth expansion unit includes the left capacitor C 42 , the right capacitor C 41 , the upper diode D 41 , the lower diode D 42 ; among them, the left end of the left capacitor C 42 in the fourth expansion unit is connected to the C' end of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C 42 is connected to the anode of the upper diode D 41 and the cathode of the lower diode D 42 , the anode of the lower diode D 42 is connected to the cathode of the upper diode D 21 in the second expansion unit, the upper end of the right capacitor C 41 is connected to the cathode of the upper diode D 41 and the right end of the first auxiliary capacitor C P1 , the lower end of the right capacitor C 41 is connected to the anode of the lower diode D 42 to form the fourth expansion unit.

[0032] Both ends of the load R are respectively connected to the upper end of the capacitor C 31 in the third expansion unit and the right end of the second auxiliary capacitor C P2 .

[0033] When switches S1 and S4 are turned on, diodes D 11 , D 21 , D 31 , D 41 conduct, diodes D P1 , D P2 and diode D 12 , D 22 , D 32 , D 42 turn off, auxiliary capacitors C P1 , C P2 and the first extended unit capacitor C 11 , the second extended unit capacitor C 21 , the third extended unit capacitor C 31 , the fourth extended unit capacitor C 41 are charged, and the AC input source u s discharges with the first extended unit capacitor C 12 , the second extended unit capacitor C 22 , the third extended unit capacitor C 32 , the fourth extended unit capacitor C 42 to supply power to the load.

[0034] When switches S2 and S3 are turned on, diodes D 11 , D 21 , D 31 , D 41 turn off, diodes D P1 , D P2 and diode D 12 , D 22 , D 32 , D 42 conduct, the AC input source u s discharges with the auxiliary capacitors C P1 , C P2 and the first extended unit capacitor C 11 , the second extended unit capacitor C 21 , the third extended unit capacitor C 31 , the fourth extended unit capacitor C 41 to supply power to the load, and the first extended unit capacitor C 12 , the second extended unit capacitor C 22 , the third extended unit capacitor C 32 , the fourth extended unit capacitor C 42 is charged.

[0035] Figure 2 As shown, an isolated voltage gain adjustable DC-DC converter includes a DC source u in, a full-bridge converter, a three-winding transformer T, and two auxiliary capacitors C P1 and C P2 , two auxiliary diodes D P1 and D P2 , 2n expansion units; n is a natural number, and the value range is n≥1; their connection form is as follows:

[0036] The full-bridge converter includes switches S1, S2, S3, S4, and the primary winding T of the transformer T P , a DC source u in The upper end of is connected to the drain of switch S1 and the drain of switch S1, and the lower end of the DC source u in is connected to the source of switch S3 and the source of switch S4. The source of switch S1 is connected to the drain of switch S3 and the A end of the primary winding T of the three-winding transformer T P The source of switch S2 is connected to the drain of switch S4 and the B end of the primary winding T of the three-winding transformer T P The gates of switches S1, S2, S3, and S4 are respectively connected to their respective controllers. Switches S1 and S4 are synchronously controlled, switches S2 and S3 are synchronously controlled, and the duty cycle is maintained at 0.5 and they conduct alternately;

[0037] The three-winding transformer T includes a primary winding T P , a secondary winding T S1 and a secondary winding T S2 , the left end of the first auxiliary capacitor C P1 is connected to the D end of the secondary winding T of the three-winding transformer T S1 , the right end of the first auxiliary capacitor C P1 is connected to the anode of the first auxiliary diode D P1 , the cathode of the first auxiliary diode D P1 is connected to the C end of the secondary winding T of the three-winding transformer T S1 , the left end of the second auxiliary capacitor C P2 is connected to the D` end of the secondary winding T of the three-winding transformer T S2 , the right end of the second auxiliary capacitor C P2 is connected to the anode of the second auxiliary diode D P2 , the cathode of the second auxiliary diode D P2 is connected to the C` end of the secondary winding T of the three-winding transformer T S2 .

[0038] Each expansion unit has the same structure and includes a left capacitor, a right capacitor, an upper diode, and a lower diode. Their connection form is as follows:

[0039] The first expansion unit includes a left capacitor C 12 and a right capacitor C11 , the upper diode D 11 , the lower diode D 12 ; among them, the left end of the left capacitor C of the first expansion unit 12 is connected to the C terminal of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C 12 is connected to the anode of the upper diode D 11 and the cathode of the lower diode D 12 . The anode of the lower diode D 12 is connected to the D terminal of the secondary winding of the three-winding transformer T. The upper end of the right capacitor C 11 is connected to the cathode of the upper diode D 11 . The lower end of the right capacitor C 11 is connected to the anode of the lower diode D 12 , forming the first expansion unit;

[0040] The second expansion unit includes the left capacitor C 22 , the right capacitor C 21 , the upper diode D 21 , the lower diode D 22 ; among them, the left end of the left capacitor C of the second expansion unit 22 is connected to the C' terminal of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C 22 is connected to the anode of the upper diode D 21 and the cathode of the lower diode D 22 . The anode of the lower diode D 22 is connected to the D' terminal of the secondary winding of the three-winding transformer T. The upper end of the right capacitor C 21 is connected to the cathode of the upper diode D 21 . The lower end of the right capacitor C 21 is connected to the anode of the lower diode D 22 , forming the second expansion unit;

[0041] When n > 1, among the 2n expansion units, the (2n - 1)-th expansion unit includes the left capacitor C (2n-1)2 , the right capacitor C (2n-1)1 , the upper diode D (2n-1)1 , the lower diode D (2n-1)2 ; among them, the left end of the left capacitor C of the (2n - 1)-th expansion unit (2n-1)2 is connected to the C terminal of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C (2n-1)2 is connected to the anode of the upper diode D (2n-1)1 and the cathode of the lower diode D (2n-1)2 . The anode of the lower diode D (2n-1)2 is connected to the upper diode D of the (2n - 3)-th expansion unit (2n-3)1The cathode connection of the right capacitor C (2n-1)1 The upper end of the upper diode D (2n-1)1 The cathode connection of the right capacitor C (2n-1)1 The lower end of the lower diode D (2n-1)2 The anode connection;

[0042] When n>1, in 2n extended units, the 2nth extended unit includes the left capacitor C (2n)2 , the right capacitor C (2n)1 , the upper diode D (2n)1 , the lower diode D (2n)2 ; Among them, the left end of the left capacitor C of the 2nth extended unit (2n)2 Is connected to the C` end of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C (2n)2 Is connected to the anode of the upper diode D (2n)1 And the cathode of the lower diode D (2n)2 , the anode of the lower diode D (2n)2 Is connected to the cathode of the upper diode D of the 2(n - 1)th extended unit 2(n-1)1 , the upper end of the right capacitor C (2n)1 Is connected to the cathode of the upper diode D (2n)1 And the right end of the first auxiliary capacitor C P1 , the lower end of the right capacitor C (2n)1 Is connected to the anode of the lower diode D (2n)2 The anode connection;

[0043] Both ends of the load R are respectively connected to the upper end of the capacitor C in the 2n - 1th extended unit (2n-1)1 And the right end of the second auxiliary capacitor C P2 Connected.

[0044] The output voltage of the isolated voltage gain adjustable DC-DC converter of the present utility model is adjusted by adjusting the number of extended units, realizing the high-gain multi-stage voltage regulation ability. The voltage gain that each extended unit can improve is 2, and the input-output voltage gain of the rectifier circuit is N1(2n + 1)+N2(2n + 1). Among them, N1 is the turns ratio of the secondary winding T of the three-winding transformer S1 And the primary winding T P Turns ratio, N2 is the turns ratio of the secondary winding T of the three-winding transformer S2 And the primary winding T P Turns ratio.

[0045] From Figure 3 It can be seen that when the input voltage is 100V and N1 = N2 = 1 with 4 extended units, the output voltage is 1000V, realizing a 10-fold voltage gain and effectively improving the voltage gain of the circuit.

[0046] The above are only specific embodiments of the present utility model, but the structural features of the present utility model are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present utility model are covered by the protection scope of the present utility model.

[0047] It should be noted that the terms "including" and "having" in the description, claims and above-mentioned drawings of the present utility model, and any variations thereof, are intended to cover non-exclusive inclusion. The terms "installed", "set", "provided with", "connected", "connected to", "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can be internal communication between two devices, components or parts. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0048] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "one end", "the other end", "outer side", "inner side", "horizontal", "end", "length", "left", "right", "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present utility model. The terms "first", "second", "third", "fourth", "the 1st", "the 2nd", "the 3rd", "the 4th" are also used only for the sake of brevity in description and do not indicate or imply relative importance.

Claims

1. An isolated voltage gain adjustable DC-DC converter, characterized in that: The converter includes a DC source u in , a full-bridge converter, a three-winding transformer T, two auxiliary capacitors C P1 , C P2 , two auxiliary diodes D P1 , D P2 , 2n expansion units, where n is a natural number and the value range is n≥1; The full-bridge converter includes four switches S1, S2, S3, and S4, and the primary winding T of the three-winding transformer T P ; and their connection form is as follows: DC source u in The upper end of is connected to the drain of switch S1 and the drain of the first switch S1. The DC source u in The lower end of is connected to the source of the third switch S3 and the source of the fourth switch S4. The source of the first switch S1 is connected to the drain of the third switch S3 and the primary winding T of the three-winding transformer T P The A end of. The source of the second switch S2 is connected to the drain of the fourth switch S4 and the primary winding T of the three-winding transformer T P The B end of. The gates of the 4 switches S1, S2, S3, and S4 are respectively connected to their respective controllers. The first switch S1 and the fourth switch S4 are synchronously controlled. The second switch S2 and the third switch S3 are synchronously controlled. The duty cycle is maintained at 0.5 and they conduct alternately; The three-winding transformer T includes a primary winding T P , a secondary winding T S1 and a secondary winding T S2 . The left end of the first auxiliary capacitor C P1 is connected to the D terminal of the secondary winding T S1 of the three-winding transformer T. The right end of the first auxiliary capacitor C P1 is connected to the anode of the first auxiliary diode D P1 . The cathode of the first auxiliary diode D P1 is connected to the C terminal of the secondary winding T S1 of the three-winding transformer T. The left end of the second auxiliary capacitor C P2 is connected to the D` terminal of the secondary winding T S2 of the three-winding transformer T. The right end of the second auxiliary capacitor C P2 is connected to the anode of the second auxiliary diode D P2 . The cathode of the second auxiliary diode D P2 is connected to the C` terminal of the secondary winding T S2 of the three-winding transformer T; Each expansion unit has the same structure and includes a left capacitor, a right capacitor, an upper diode, and a lower diode. Their connection form is as follows: When n = 1, the left end of the capacitor C on the left side of the first extended unit 12 is connected to the C terminal of the secondary winding of the three-winding transformer T. The right end of the left capacitor C 12 is connected to the anode of the upper diode D 11 and the cathode of the lower diode D 12 . The anode of the lower diode D 12 is connected to the D terminal of the secondary winding of the three-winding transformer T. The upper end of the right capacitor C 11 is connected to the cathode of the upper diode D 11 . The lower end of the right capacitor C 11 is connected to the anode of the lower diode D 12 , forming the first extended unit; The left end of the capacitor C on the left side of the second extended unit 22 is connected to the C' terminal of the secondary winding of the three-winding transformer T. The right end of the left capacitor C 22 is connected to the anode of the upper diode D 21 and the cathode of the lower diode D 22 . The anode of the lower diode D 22 is connected to the D' terminal of the secondary winding of the three-winding transformer T. The upper end of the right capacitor C 21 is connected to the cathode of the upper diode D 21 . The lower end of the right capacitor C 21 is connected to the anode of the lower diode D 22 , forming the second extended unit; When n > 1, among the 2n extended units, the (2n - 1)-th extended unit includes a left capacitor C (2n-1)2 , a right capacitor C (2n-1)1 , an upper diode D (2n-1)1 , and a lower diode D (2n-1)2 ; where the left end of the left capacitor C (2n-1)2 in the (2n - 1)-th extended unit is connected to the C terminal of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C (2n-1)2 is connected to the anode of the upper diode D (2n-1)1 and the cathode of the lower diode D (2n-1)2 , the anode of the lower diode D (2n-1)2 is connected to the cathode of the upper diode D (2n-3)1 in the (2n - 3)-th extended unit, the upper end of the right capacitor C (2n-1)1 is connected to the cathode of the upper diode D (2n-1)1 , and the lower end of the right capacitor C (2n-1)1 is connected to the anode of the lower diode D (2n-1)2 ; among the 2n extended units, the 2n-th extended unit includes a left capacitor C (2n)2 , a right capacitor C (2n)1 , an upper diode D (2n)1 , and a lower diode D (2n)2 ; where the left end of the left capacitor C (2n)2 in the 2n-th extended unit is connected to the C' terminal of the secondary winding of the three-winding transformer T, and the right end of the left capacitor C (2n)2 is connected to the anode of the upper diode D (2n)1 and the cathode of the lower diode D (2n)2 , the anode of the lower diode D (2n)2 is connected to the cathode of the upper diode D 2(n-1)1 in the 2(n - 1)-th extended unit, the upper end of the right capacitor C (2n)1 is connected to the cathode of the upper diode D (2n)1 and the right end of the first auxiliary capacitor C P1 , and the lower end of the right capacitor C (2n)1 is connected to the anode of the lower diode D (2n)2 ; Both ends of the load R are respectively connected to the upper end of the capacitor C in the (2n - 1)-th extended unit and the right end of the second auxiliary capacitor C (2n-1)1 P2 .​ 2. The isolated voltage gain adjustable DC-DC converter according to claim 1, wherein: When 4 extension units are adopted and the first switch S1 and the second switch S4 are turned on, the upper diodes D of the first extension unit 11 、the upper diodes D of the second extension unit 21 、the upper diodes D of the third extension unit 31 、the upper diodes D of the fourth extension unit 41 conduct, the first auxiliary diodes D P1 、the second auxiliary D P2 and the lower diodes D of the first extension unit 12 、the lower D of the second extension unit 22 、the lower D of the third extension unit 32 、the lower D of the fourth extension unit 42 turn off, two auxiliary capacitors C P1 、C P2 and the right capacitors C of the first extension unit 11 、the right capacitors C of the second extension unit 21 、the right capacitors C of the third extension unit 31 、the right capacitors C of the fourth extension unit 41 are charged, and the AC input source u s discharges with the left capacitors C of the first extension unit 12 、the left capacitors C of the second extension unit 22 、the left capacitors C of the third extension unit 32 、the left capacitors C of the fourth extension unit 42 to supply power to the load.

3. The isolated voltage gain adjustable DC-DC converter according to claim 1, wherein: When 4 extension units are adopted and the second switch S2 and the third switch S3 are turned on, the upper diodes D of the first extension unit 11 、the upper diodes D of the second extension unit 21 、the upper diodes D of the third extension unit 31 、the upper diodes D of the fourth extension unit 41 are turned off, and the first auxiliary diodes D P1 、the second auxiliary D P2 and the lower diodes D of the first extension unit 12 、the lower D of the second extension unit 22 、the lower D of the third extension unit 32 、the lower D of the fourth extension unit 42 are turned on. The AC input source u s discharges with two auxiliary capacitors C P1 、C P2 and the right capacitors C of the first extension unit 11 、the right capacitors C of the second extension unit 21 、the right capacitors C of the third extension unit 31 、the right capacitors C of the fourth extension unit 41 to supply power to the load, and the left capacitors C of the first extension unit 12 、the left capacitors C of the second extension unit 22 、the left capacitors C of the third extension unit 32 、the left capacitors C of the fourth extension unit 42 are charged.

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