DC-DC converters and power supplies

Abstract

The present application discloses a DC-DC converter and a power supply device, the converter including a power supply input terminal configured to be connected to a DC power supply, a power supply output terminal configured to output a power supply, M bridge arm circuits having an input terminal connected to the power supply input terminal, a transformer assembly having a primary coil connection terminal of each transformer connected to a midpoint of the M bridge arm circuits, and a rectifier / filter circuit having an input terminal connected to a secondary coil connection terminal of the transformer assembly and an output terminal connected to a power supply output terminal, wherein the M bridge arm circuits and the transformer assembly are configured to convert the connected DC power supply to a required voltage in the secondary coil of the transformer assembly, and output the voltage to the power supply output terminal after being rectified and filtered by the rectifier / filter circuit, where M≧3.

Description

Related Applications

[0001] This application claims priority to a Chinese patent application filed on June 15, 2021, with application number 202121328038.3, and a Chinese patent application filed on June 15, 2021, with application number 202110663929.2, the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] This application relates to the technical field of power supplies, and more particularly to DC-DC converters and power supplies. [Background technology]

[0003] In a conventional phase-shifted full-bridge architecture, the output voltage is adjusted by changing the duty cycle. Refer to Figures 7 and 8. Figure 7 is a schematic diagram of a DC-DC converter with a phase-shifted full-bridge architecture, and Figure 8 is a timing diagram of a DC-DC converter with a phase-shifted full-bridge architecture. The following analysis is based on the situation where the minimum current of inductor L1 is greater than zero. At t0, the freewheeling ends, Q22 turns off, and the transformer leakage inductance begins to enter a resonant state, charging point V2 and increasing the voltage. At t1, after the voltage at point V2 reaches its peak, Q21 soft-turns on. Q21 and Q12 work together, rectifying the transformer secondary and outputting energy. At t2, Q12 turns off. The transformer primary current charges V1. At t3, after the voltage at point V1 reaches its peak, Q11 soft-turns on. The transformer output voltage is zero. The transformers Tx, Q11, and Q21 enter a freewheeling state. In this state, energy is wasted in the transistors and transformer coils. At t4, freewheeling ends, Q21 turns off, and the transformer's leakage inductance begins to resonate, discharging point V2 and reducing the voltage. At t5, the voltage at point V2 reaches its lowest point, and Q22 soft-turns on. Q22 and Q11 work together, rectifying the secondary side of the transformer and outputting energy. At t6, Q11 turns off. The transformer primary current discharges point V1, reducing the voltage. At t7, the voltage at point V1 reaches its lowest point, and Q12 soft-turns on. The transformer output voltage is 0. The transformers Tx, Q12, and Q22 enter a freewheeling state. In this state, energy is wasted in the transistors and transformer coils. Since it cannot operate at 100% duty cycle to accommodate instantaneous changes in load, reflux current losses occur. Summary of the Invention [Problem to be solved by the invention]

[0004] The main object of the present application is to propose a DC-DC converter and a power supply device that aim to reduce the resistance loss, especially the return current loss, of the bridge arm circuit and the transformer. [Means for solving the problem]

[0005] In order to achieve the above object, the present application proposes a DC-DC converter, the DC-DC converter comprising: a power supply input terminal configured to be connected to a DC power supply; a power output terminal configured to output a power supply; M bridge arm circuits each having an input terminal connected to a power supply input terminal; a transformer assembly including M-1 transformers, wherein the M-1 transformers have at least two different types of turns ratios, each of the transformers including two primary coil connection terminals, one primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the Nth bridge arm circuit, and another primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the N+1th bridge arm circuit, wherein 1≦N≦M-1; a rectifier filter circuit having input terminals connected to secondary coil connection terminals of the transformer assembly and output terminals connected to the power supply output terminals; The M bridge arm circuits and the transformer assembly are configured to convert the connected DC power supply into a required voltage in the secondary coil of the transformer assembly, rectify and filter the voltage in the rectifier / filter circuit, and then output the voltage to the power supply output terminal, where M≧3.

[0006] In one embodiment, the states of two adjacent transformers are changed simultaneously by changing the state of a switch in a bridge arm circuit connected to both of the two adjacent transformers.

[0007] In one embodiment, when one of the M−1 transformers has at least one end disconnected and the operation of the transformer is switched on, the lower arm transistor of the bridge arm circuit, from which the magnetizing current flows out at the midpoints of the two bridge arms connected to the primary coil connection terminals, is turned on, and the upper arm transistor of the bridge arm circuit, into which the magnetizing current flows in at the midpoints of the bridge arms, is turned on, so as to minimize switching loss in the bridge arm circuit.

[0008] In one embodiment, when one of the M−1 transformers has at least one end disconnected and is switched on, the lower arm transistor of the bridge arm circuit, into which the magnetizing current flows out at the midpoint of the two bridge arms connected to the primary coil connection terminals, is turned on, and the upper arm transistor of the bridge arm circuit, into which the magnetizing current flows in at the midpoint of the bridge arm, is turned on, so that the switching loss of the bridge arm circuit is minimized. Another transformer that is already connected to the DC power supply and operating operates while maintaining the state of its bridge arm switch, so that the two transformers mentioned above are simultaneously connected to the DC power supply and operating.

[0009] In one embodiment, the DC-DC converter has an alternating phase-shifted full-bridge operation mode, in which the primary sides of the M-1 transformers operate sequentially at the DC power supply voltage and zero voltage over one or more control periods; and / Or, In one control cycle, one of the transformers is first connected to the DC power supply via the corresponding bridge arm and operates, and then both ends of the transformer are short-circuited via the corresponding bridge arm and operates in this manner over one or more control cycles, and the M-1 transformers operate in cycles in sequence.

[0010] In one embodiment, the DC-DC converter has a dual mode operation mode, and in the dual mode operation mode, the 1st to (M-1)th transformers are operated in sequence with the DC power supply voltage within one control period, and then the (M-1)th transformer is refluxed at zero voltage. 、 In one embodiment, in dual mode operation: When the last transformer is switched on, the last two transformers are simultaneously connected to the DC power supply and operate. 、 In one embodiment, the DC-DC converter has a dual mode operation mode, in which: In one control period, the M-1 transformers start one cycle from any one of them, and are connected to the DC power source through the corresponding bridge arm in order to operate. After the cycle, the last transformer is circulated by short-circuiting both ends of the last transformer through the corresponding bridge arm. 、 In one embodiment, in dual mode operation: When the last transformer is switched on, the last two transformers are simultaneously connected to the DC power supply and operate.

[0011] In one embodiment, the DC-DC converter has a semi-integrated operation mode, in which the first to (M-1)th transformers are operated in sequence with the DC power supply voltage within one control period, and then (M-1) transformers are operated simultaneously. 、 In one embodiment, in the semi-integrated mode of operation: When the last transformer is switched on, the last two transformers are simultaneously connected to the DC power supply and operate. 、 In one embodiment, In the semi-integrated operation mode, within one control period, the M-1 transformers start one cycle from any one of the transformers, and are connected to the DC power source through the corresponding bridge arms in order to operate. After the cycle, the M-1 transformers operate simultaneously in series. 、 In one embodiment, in the semi-integrated mode of operation: When the last transformer is switched on, the last two transformers are simultaneously connected to the DC power supply and operate.

[0012] In one embodiment, the DC-DC converter has a full integration operation mode, and in the full integration operation mode, the 1st to M-1th transformers are operated in sequence with the DC power supply voltage within one control period. 、 In one embodiment, In the total integrated operation mode, the control period is adjusted according to the change in the input voltage and the duty ratio of each transformer so that the maximum magnetic flux of any of the M-1 transformers does not exceed the maximum allowable value of the magnetic material; In one embodiment, in the fully integrated operating mode, when the last transformer is switched to operate, the last two transformers are simultaneously connected to the DC power source and operate. 、 In one embodiment, in the fully integrated mode of operation: In one control period, the M-1 transformers start one cycle from any one of the transformers, and are connected to the DC power source through the corresponding bridge arm in order to operate. 、 In one embodiment, In the total integrated operation mode, the control period is adjusted according to the change in the input voltage and the duty ratio of each transformer so that the maximum magnetic flux of any of the M-1 transformers does not exceed the maximum allowable value of the magnetic material. 、 In one embodiment, in the fully integrated mode of operation: When the last transformer is switched on, the last two transformers are simultaneously connected to the DC power supply and operate.

[0013] In one embodiment, the DC-DC converter has an alternating phase-shifted full-bridge operation mode, a dual-mode operation mode, a semi-integrated operation mode, and a full-integrated operation mode; In an alternating phase-shifted full-bridge operating mode, the primary sides of the M-1 transformers are sequentially operated at the DC power supply voltage and zero voltage for one or more control periods; In the dual mode operation mode, the primary sides of the 1st to (M-1th) transformers operate in sequence with the DC power supply voltage within one control period, and then the (M-1th) transformer is refluxed at zero voltage; In the semi-integrated operation mode, the primary sides of the 1st to (M-1th) transformers are operated in sequence with the DC power supply voltage within one control period, and then the (M-1) transformers are operated simultaneously; In the full integrated operation mode, the primary sides of the 1st to (M-1th) transformers are operated with the DC power supply voltage in sequence within one control period; The DC-DC converter further includes a main controller connected to controlled terminals of bridge arm switches in the M bridge arm circuits, respectively, and configured to operate the transformer assembly in one or a combination of multiple modes of an alternating phase-shifted full-bridge operation mode, a dual-mode operation mode, a semi-integrated operation mode, and a full-integrated operation mode by controlling the on / off of corresponding bridge arm switches in the M bridge arm circuits during operation of the DC-DC converter.

[0014] In one embodiment, in a dual mode operation mode, a semi-integrated operation mode, or a fully integrated operation mode, when the last transformer is switched on, the last two transformers are simultaneously connected to the DC power source and operate.

[0015] In one embodiment, in the fully integrated operation mode, the control period is adjusted in response to changes in the input voltage and the duty ratio of each transformer so that the maximum magnetic flux of any of the M-1 transformers does not exceed the maximum allowable value of the magnetic material.

[0016] In one embodiment, as the equivalent full-bridge duty ratio changes, the switching between any two modes has hysteresis of the equivalent full-bridge duty ratio change.

[0017] In one embodiment, the DC-DC converter has an alternating full-bridge operation mode, in which, in one control cycle, one of the M-1 transformers is first connected to the DC power source through a corresponding bridge arm, and then the input terminal of the transformer is disconnected by turning off all bridge arms connected to the transformer, and the transformer thus operates over one or more control cycles, and the M-1 transformers operate in a cycle in turn.

[0018] In one embodiment, the DC-DC converter has an individual full-bridge operation mode, in which only one of the M-1 transformers operates, and in one control period, the transformer is first connected to the DC power source through a corresponding bridge arm, and then all bridge arms connected to the transformer are turned off to disconnect the input terminals of the transformer.

[0019] In one embodiment, the DC-DC converter has an individual phase-shifted full-bridge operation mode, in which only one of the M-1 transformers operates, and in one control period, the transformer first operates by being connected to the DC power source via a corresponding bridge arm, and then operates in a manner in which both ends of the transformer are short-circuited via the corresponding bridge arm.

[0020] In another embodiment, the DC-DC converter has at least one of an individual phase-shifted full-bridge operating mode, an individual full-bridge operating mode, an alternating full-bridge operating mode, an alternating phase-shifted full-bridge operating mode, a dual-mode operating mode, a semi-integrated operating mode, and a full-integrated operating mode; In the individual phase-shifted full-bridge operation mode, only one of the M-1 transformers operates, and in one control period, the transformer is first connected to the DC power source through a corresponding bridge arm, and then both ends of the transformer are short-circuited through the corresponding bridge arm; In the individual full-bridge operation mode, only one of the M-1 transformers operates, and in one control period, the transformer is first connected to the DC power source through a corresponding bridge arm, and then all bridge arms connected to the transformer are turned off to disconnect the input terminal of the transformer; In the alternating full-bridge operation mode, in one control period, one transformer among the M-1 transformers is first connected to the DC power supply through a corresponding bridge arm, and then the input terminal of the transformer is disconnected by turning off all bridge arms connected to the transformer, and the transformer thus operates for one or more control periods, and then the M-1 transformers operate in a cycle in turn; In the alternating phase-shifted full-bridge operation mode, in one control period, one of the transformers is first connected to the DC power source through a corresponding bridge arm and operates, and then both ends of the transformer are short-circuited through a corresponding bridge arm and operates, and the transformer operates in this manner over one or more control periods, and the M-1 transformers operate in a cycle in turn; In the dual mode operation mode, within one control period, one cycle of the M-1 transformers is started from any one of the transformers, and sequentially connected to the DC power source via a corresponding bridge arm to operate; after the cycle, the last one of the transformers is circulated by short-circuiting both ends of the last one of the transformers via a corresponding bridge arm; In the semi-integrated operation mode, within one control period, the M-1 transformers start one cycle from any one of the transformers, and are sequentially connected to the DC power source via corresponding bridge arms to operate, and then the M-1 transformers operate simultaneously in series; In the total integrated operation mode, within one control period, the M-1 transformers start one cycle from any one of the transformers, and are sequentially connected to the DC power source via corresponding bridge arms to operate; The DC-DC converter further includes a main controller connected to controlled terminals of bridge arm switches in the M bridge arm circuits, respectively, and the main controller is configured to operate the transformer assembly in one or a combination of multiple modes from an individual phase-shifted full-bridge operation mode, an individual full-bridge operation mode, an alternating full-bridge operation mode, an alternating phase-shifted full-bridge operation mode, a dual-mode operation mode, a semi-integrated operation mode, and a full-integrated operation mode by controlling the on / off of corresponding bridge arm switches in the M bridge arm circuits during operation of the DC-DC converter.

[0021] In one embodiment, in a dual mode operation mode, a semi-integrated operation mode, or a fully integrated operation mode, when the last transformer is switched on, the last two transformers are simultaneously connected to the DC power source and operate.

[0022] In one embodiment, in the fully integrated operation mode, the control period is adjusted in response to changes in the input voltage and the duty ratio of each transformer so that the maximum magnetic flux of any of the M-1 transformers does not exceed the maximum allowable value of the magnetic material.

[0023] In one embodiment, as the equivalent full-bridge duty ratio changes, the switching between any two modes has hysteresis of the equivalent full-bridge duty ratio change.

[0024] In one embodiment, when M is 3, the three bridge arm circuits include a first bridge arm switch, a second bridge arm switch, a third bridge arm switch, a fourth bridge arm switch, a fifth bridge arm switch and a sixth bridge arm switch; the first bridge arm switch and the second bridge arm switch are connected in series to form a first bridge arm circuit; the third bridge arm switch and the fourth bridge arm switch are connected in series to form a second bridge arm circuit; The fifth bridge arm switch and the sixth bridge arm switch are connected in series to form a third bridge arm circuit.

[0025] In one embodiment, in the alternating phase-shift full-bridge operation mode, when the main controller controls the two bridge arm switches of the second bridge arm circuit to be turned on / off, the main controller controls the two bridge arm switches of one of the first bridge arm circuit and the third bridge arm circuit to be turned on / off, and controls the two bridge arm switches of the other bridge arm circuit to be turned off; or In the dual mode operation mode, the main controller controls the second bridge arm switch to be turned off first and then the fifth bridge arm switch to be turned on, the first bridge arm switch to be turned off first and then the sixth bridge arm switch to be turned on, the main controller controls the second bridge arm switch to be turned on first and then the sixth bridge arm switch to be turned off, the first bridge arm switch to be turned on first and then the fifth bridge arm switch to be turned off, or In the semi-integrated operation mode or the fully integrated operation mode, the main controller controls the third bridge arm switch to be turned on first, then the first bridge arm switch to be turned off, the fourth bridge arm switch to be turned on first, then the second bridge arm switch to be turned off, the main controller controls the second bridge arm switch to be turned on first, then the sixth bridge arm switch to be turned off, the first bridge arm switch to be turned on first, then the fifth bridge arm switch to be turned off, the main controller controls the fifth bridge arm switch to be turned on first, then the fourth bridge arm switch to be turned on, the sixth bridge arm switch to be turned on first, then the third bridge arm switch to be turned on.

[0026] The present application further proposes a power supply device including a DC-DC converter as described above.

[0027] According to the DC-DC converter of the present application, M bridge arm circuits, a transformer assembly, and a rectifying / filtering circuit are provided between a power supply input terminal and a power supply output terminal. The M bridge arm circuits and the transformer assembly convert the connected DC power supply to a required voltage, which is then rectified and filtered before being output to the power supply output terminal. During operation of the DC-DC converter, the transformers in the transformer assembly operate alternately and / or simultaneously at a fixed time rate by turning on / off the bridge arm switches of each bridge arm circuit at their respective timings. This reduces loss when the bridge arm switches are turned on by charging and discharging using the residual energy of the leakage inductance and magnetizing current of the transformers. In a conventional phase-shift full-bridge architecture, the output voltage is adjusted by changing the duty cycle, but it cannot operate at a 100% duty cycle to accommodate instantaneous changes in the load, resulting in reflux current loss. According to the present invention, the resistance loss of the bridge arm circuit and the transformer, especially the return current loss, can be reduced, and the size of the heat sink of the DC-DC converter can be reduced, which is advantageous for energy saving and emission reduction. [Brief explanation of the drawings]

[0028] In order to more clearly explain the technical solutions of the embodiments of the present application and the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. It is clear that the accompanying drawings in the following description are only some of the embodiments of the present application, and those skilled in the art can obtain other accompanying drawings from the structures shown in these accompanying drawings without creative work.

[0029] [Figure 1] 1 is a schematic diagram showing a circuit configuration of an embodiment of a DC-DC converter according to the present invention;

[0030] [Figure 2] FIG. 2 is a schematic diagram of a circuit configuration of another embodiment of a DC-DC converter according to the present invention.

[0031] [Figure 3]FIG. 2 is a timing diagram of the present DC-DC converter operating in an alternating phase-shifted full-bridge mode of operation.

[0032] [Figure 4] FIG. 2 is a timing diagram of the DC-DC converter of the present application operating in a dual-mode operation mode.

[0033] [Figure 5] FIG. 2 is a timing diagram of the DC-DC converter of the present application operating in a semi-integrated mode of operation.

[0034] [Figure 6] FIG. 2 is a timing diagram of the DC-DC converter of the present application operating in a fully integrated mode of operation.

[0035] [Figure 7] FIG. 1 is a schematic diagram showing the circuit configuration of a DC-DC converter with a conventional phase-shift full-bridge architecture.

[0036] [Figure 8] FIG. 8 is a timing diagram of the phase-shifted full-bridge architecture DC-DC converter of FIG. 7. [Explanation of symbols]

[0037] [Table 1]

[0038] The realization of the object, function features and advantages of the present invention will be further explained in combination with the embodiments with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION

[0039] The following will clearly and completely explain the technical solutions in the embodiments of the present application in combination with the drawings in the embodiments of the present application. It is clear that the described embodiments are not all of the embodiments of the present application, but only some of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments that can be obtained by those skilled in the art without any creative work fall within the scope of protection of the present application.

[0040] If the embodiments of the present application involve directional indications (e.g., up, down, left, right, front, back, etc.), it should be explained that the directional indications are used only to describe the relative positional relationships, movement conditions, etc. between each part in a certain specific position (as shown in the attached drawings), and if the specific position changes, the directional indications will also change accordingly.

[0041] Furthermore, when the embodiments of the present application refer to "first," "second," etc., the terms "first," "second," etc. are used for explanatory purposes only and should not be understood as indicating or implying the relative importance of the features or implicitly specifying the number of technical features presented. Therefore, features defined as "first" or "second" may explicitly or implicitly include at least one of the features. Furthermore, the technical solutions of each embodiment may be combined with each other, provided that such combination is feasible by a person skilled in the art. If a combination of technical solutions is inconsistent or cannot be realized, it should be understood that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present application.

[0042] The term "and / or" in this specification describes the relation between related objects and simply means that three relations may exist. For example, in the case of A and / or B, three situations can be represented: only A exists, A and B exist simultaneously, or only B exists. Note that in this specification, the symbol " / " usually indicates that the related objects before and after it are in an "or" relation.

[0043] This application proposes a DC-DC converter.

[0044] Referring to FIGS. 1 to 6, in the embodiment of the present application, the DC-DC converter comprises: a power supply input terminal V-in configured to be connected to a DC power supply; a power supply output terminal V-out configured to output a power supply; M bridge arm circuits 10 each having an input terminal connected to a power supply input terminal V-in, each bridge arm circuit including two switching transistors arranged to be connected in series, and the bridge arm circuits are arranged to be connected in parallel with each other, and the switching transistors can be realized using power transistors such as MOSFETs, IGBTs, GANFETs, and SiCFETs; a transformer assembly 20 in which a primary coil connection terminal of each transformer is connected to a midpoint of the M bridge arm circuits; The transformer assembly 20 includes M-1 transformers Tx1 to Tx M-1 The M-1 transformers Tx1 to Tx M-1 are provided with at least two types of transformers with different turns ratios, each of the transformers including two primary coil connection terminals, one primary coil connection terminal of the Nth transformer being connected to the bridge arm midpoint of the Nth bridge arm circuit, and the other primary coil connection terminal of the Nth transformer being connected to the bridge arm midpoint of the N+1th bridge arm circuit, where 1≦N≦M−1.

[0045] Specifically, one primary coil connection terminal of the first transformer is connected to the bridge arm midpoint of the first bridge arm circuit, the other primary coil connection terminal of the first transformer is connected to the bridge arm midpoint of the second bridge arm circuit, one primary coil connection terminal of the second transformer is connected to the bridge arm midpoint of the second bridge arm circuit, the other primary coil connection terminal of the second transformer is connected to the bridge arm midpoint of the third bridge arm circuit, and so on, until one primary coil connection terminal of the (M-1)th transformer is connected to the bridge arm midpoint of the (M-1)th bridge arm circuit, and the other primary coil connection terminal of the (M-1)th transformer is connected to the bridge arm midpoint of the Mth bridge arm circuit. The term "connection" used herein refers to electrical connection, and the present application does not limit the physical connection method between the primary coil terminals of two adjacent transformers and the midpoints of the corresponding bridge arms.

[0046] The transformer coil of the transformer assembly 20 may be set to step-down or step-up.

[0047] The rectifier filter circuit 30 has an input terminal connected to the secondary coil connection terminal of the transformer assembly 20 and an output terminal connected to the power supply output terminal. The rectifier filter circuit 30 may be implemented using elements such as a rectifier diode, an inductor, and a capacitor. Specifically, the DC-DC converter is located on the secondary coil of the transformer; that is, a diode is provided on the output side for rectification, which may be a parasitic diode of a synchronous rectifier transistor. The connection relationship of the diodes in the circuit may be adaptively adjusted depending on the actual application and is not limited here. An inductor L1 and a capacitor C1 are provided on the output side of the DC-DC converter. The inductor L1 is connected in series between the secondary coil connection terminal or the output terminal of the rectifier diode and the power supply output terminal V-out, and the capacitor C1 is connected to the power supply output terminal V-out.

[0048] The M bridge arm circuits 10 and the transformer assembly 20 are configured to convert the connected DC power supply into a required voltage in the secondary coil of the transformer assembly 20, rectify and filter the voltage in the rectifying and filtering circuit 30, and then output the voltage to the power supply output terminal, where M≧3.

[0049] According to the DC-DC converter of the present application, M bridge arm circuits 10, a transformer assembly 20, and a rectifier / filter circuit 30 are provided between a power supply input terminal V-in and a power supply output terminal V-out. The M bridge arm circuits 10 and the transformer assembly 20 convert the connected DC power supply to a required voltage, which is then output to the power supply output terminal V-out via the rectifier / filter circuit 30. During operation of the DC-DC converter, the bridge arm switches of each bridge arm circuit are turned on / off at their respective timings, so that the transformers in the transformer assembly 20 operate alternately and / or simultaneously at a fixed time ratio. This reduces loss when the bridge arm switches are turned on by charging and discharging using the residual energy of the leakage inductance and magnetizing current of the transformers. In a conventional phase-shift full-bridge architecture, the output voltage is adjusted by changing the duty cycle, but it cannot operate at a 100% duty cycle to accommodate instantaneous changes in the load, resulting in reflux current loss. This invention reduces the resistance loss of the bridge arm circuit and the transformer, especially the return current loss, and further reduces the size of the heat sink, which is advantageous for energy conservation and emission reduction.

[0050] The states of two adjacent transformers are changed simultaneously by changing the states of the switches in the bridge arm circuits connected to both of the two adjacent transformers. Referring to FIG. 1 , in one embodiment, in the initial state, Q11 is on, Q12 is off, Q21 is off, Q22 is on, Q31 is off, and Q32 is on. Ideally, the voltage across Tx1 is the DC power supply voltage, and the voltage across Tx2 is zero. Without changing the states of Q11 and Q12, Q22 is turned off, and Q21 is turned on again after a dead time. Ideally, the voltage across Tx1 is zero, and the voltage across Tx2 is the DC power supply voltage.

[0051] one transformer outputs energy outward while operating at said DC power supply voltage; When one of the M-1 transformers has at least one end disconnected, the lower-arm transistors of the bridge arm circuits, through which the magnetizing current flows at the two bridge arm midpoints connected to the primary coil connection terminals, turn on, and the upper-arm transistors of the bridge arm circuits, through which the magnetizing current flows at the bridge arm midpoints, turn on, to minimize switching losses in the bridge arm circuits. Referring to FIG. 1 , in one embodiment, in the initial state, Q11 and Q12 are off, and the magnetizing current of Tx1 flows out from point V1 and in from point V2. Because both Q11 and Q12 associated with point V1 are off, point V1 is disconnected, and the voltage at point V1 continues to decrease as the magnetizing current of Tx1 discharges. As the voltage at point V1 decreases, switching losses due to Q12 turning on decrease.

[0052] one transformer outputs energy outward while operating at said DC power supply voltage;When one of the M-1 transformers has at least one end disconnected, the lower-arm transistors of the bridge arm circuit, through which the magnetizing current flows at the midpoints of the two bridge arms connected to the primary coil connection terminals, turn on, and the upper-arm transistors of the bridge arm circuit, through which the magnetizing current flows at the midpoints of the bridge arms, turn on, so as to minimize switching losses in the bridge arm circuits. The other transformer, already connected to the DC power supply and operating, operates while maintaining the state of its bridge arm switch. Thus, the two transformers are simultaneously connected to the DC power supply and operating. Referring to FIG. 1 , in one embodiment, in the initial state, Q11 is off, Q12 is off, Q21 is on, Q22 is off, Q31 is off, and Q32 is on. Tx2 is connected to the DC power supply and operating. The magnetizing current of Tx1 flows out from point V1 and into point V2. Since both Q11 and Q12 related to V1 are off, V1 is in a disconnected state, and the voltage at V1 continues to decrease as the Tx1 magnetizing current discharges. As the voltage at V1 decreases, the switching loss caused by turning on Q12 decreases. After Q12 turns on, transformers Tx1 and Tx2 operate simultaneously.

[0053] 7 and 8, the number of turns of the primary coil and the secondary coil of the transformer Tx of the conventional phase-shift full-bridge DC-DC converter are 2KN and 2k, respectively. Considering the balance of positive and negative magnetic flux, the maximum magnetic flux B max The calculation formula is as follows:

number

[0054] Here, VBUS is the DC power supply voltage, D is the equivalent duty ratio of the full-bridge transformer Tx, T is the switching period of the full-bridge DC-DC converter, 2kN is the number of turns of the primary coil of the full-bridge transformer Tx, and Ae is the equivalent cross-sectional area of ​​the full-bridge transformer Tx.

[0055] 1 to 6, in one embodiment, M is 3, and the number of transformers suitable for a three-bridge architecture with three bridge arm circuits is 2. The two transformers Tx1 and Tx2 may operate in a manner with the same magnetic flux or in a manner with asymmetric magnetic flux, as long as it can be guaranteed that the maximum magnetic flux does not exceed the maximum magnetic flux of the transformer material.

[0056] The three-bridge transformer Tx1 divides the full-bridge transformer core in half while keeping the equivalent cross-sectional area of ​​the new transformer core constant, i.e., Ae1 = Ae, and places half of the primary and secondary coils in half the space, further completing the magnetic circuit along the cross section. The number of turns of the primary and secondary coils of the three-bridge transformer Tx1 are kN and k, respectively, and the resistance of both has been halved compared to the full-bridge transformer.

[0057] The three-bridge transformer Tx2 may use a magnetic core similar to that of the transformer Tx1, and the number of turns of the primary coil and the secondary coil may be adjusted to pkN and k, where p is 1 or greater.

[0058] Considering the balance of positive and negative magnetic flux, the maximum magnetic flux B in the transformer Tx1 of the DC-DC converter with three-bridge architecture is 1max The calculation formula is as follows:

number

[0059] where VBUS is the DC power supply voltage, D1 is the equivalent duty ratio of the transformer Tx1, T is the switching period of the three-bridge DC-DC converter, kN is the number of turns in the primary coil of the transformer Tx1, and Ae and Ae1 are the equivalent cross-sectional areas of the transformers Tx and Tx1.

[0060]

number

[0061]

number

[0062] Under steady state and the same output voltage current, the three-bridge converter has the same inductor current as the full-bridge converter. For ease of comparison, the three-bridge converter and the full-bridge converter use transistors with the same resistance values.

[0063] The primary coil resistance of the three-bridge transformer Tx1 is half that of the full-bridge transformer Tx. Since the inductor current and turns ratio during independent operation are the same as those of the full-bridge transformer, the primary current is also the same. The instantaneous resistance loss of the primary coil during independent operation is half that of the full-bridge transformer, and the instantaneous resistance loss of the transistors is the same as that of the full-bridge transformer.

[0064]

number

[0065]

number

[0066]

number

[0067] When the inductor current of the conventional full-bridge architecture is greater than zero and the output voltage current is in steady state, the following equation can be derived based on the inductor current balance:

number

[0068] where VBUS is the DC power supply voltage, VOUT is the output power supply voltage, N is the turns ratio between the primary and secondary sides of the full-bridge transformer Tx, and D is the equivalent duty ratio of the transformer Tx.

[0069] When the inductor current in full integration mode is greater than zero and the output voltage current is in steady state, the following equation can be derived based on the inductor current balance:

number

[0070] where VBUS is the DC power supply voltage, VOUT is the output power supply voltage, N, N1 and N2 are the primary and secondary coil turns ratios of the transformers Tx, Tx1 and Tx2, respectively, and D1 and D2 are the equivalent duty ratios of the transformers Tx1 and Tx2.

[0071] By simplifying, the following equation can be derived:

number

[0072]

number

[0073] As can be seen from the above, the total primary and secondary resistance losses of the three-bridge transformers Tx1 and Tx2 are at least halved compared to a full-bridge transformer, while the total transformer space remains essentially unchanged (the transformer space is doubled in the conventional interleave architecture). Considering the skin effect and proximity effect, the total resistance loss of the two transformers in the three-bridge converter is significantly reduced when the number of coil turns is reduced. In dual mode and semi-integrated operation modes, the total bridge arm switching transistor resistance loss in the primary bridge arm circuit of the three-bridge converter is reduced to some extent. In full-integrated operation mode, the total bridge arm switching transistor resistance loss in the primary bridge arm circuit of the three-bridge converter is less than the value minus the reflux loss of the phase-shifted full-bridge architecture.

[0074] 1 to 6, in one embodiment, the transformer Tx1 of the three-bridge DC-DC converter of the present application may have the same number of turns as the transformer of the full-bridge DC-DC converter, with the primary coil and secondary coil having 2kN and 2k turns, respectively. In this case, a magnetic core with half the cross-sectional area may be used, i.e., Ae1=0.5Ae. Considering the balance of positive and negative magnetic flux, the maximum magnetic flux B in the transformer Tx1 of the DC-DC converter with three-bridge architecture of the present application may be set to 1max The calculation formula is as follows:

number

[0075] Here, VBUS is the DC power supply voltage, D1 is the equivalent duty ratio of the transformer Tx1, T is the switching period of the three-bridge DC-DC converter, 2kN is the number of turns in the primary coil of the transformer Tx1, and Ae and Ae1 are the equivalent cross-sectional areas of the transformers Tx and Tx1.

[0076]

number

[0077] The design of the transformer Tx2 in this example can refer to the previous example.

[0078] Referring to FIGS. 1 to 6, in one embodiment, the DC-DC converter has an alternating phase-shifted full-bridge operation mode, a dual-mode operation mode, a semi-integrated operation mode and a full-integrated operation mode. The DC-DC converter further includes a main controller connected to controlled terminals of the bridge arm switches in the M bridge arm circuits, respectively, and the main controller is configured to operate the transformer assembly 20 in one or a combination of a plurality of modes selected from an alternating phase-shift full-bridge operation mode, a dual-mode operation mode, a semi-integrated operation mode, and a full-integrated operation mode by controlling the on / off of corresponding bridge arm switches in the M bridge arm circuits during operation of the DC-DC converter.

[0079] In this embodiment, when the DC-DC converter operates in the alternating phase-shift full-bridge operation mode, the dual-mode operation mode, the semi-integrated operation mode, and the full-integrated operation mode, the four modes have different timings and can accommodate applications with different duty cycles. When the equivalent full-bridge duty cycle (i.e., the duty cycle required to use a conventional full-bridge topology) is relatively small, the alternating phase-shift full-bridge operation mode or the dual-mode operation mode can be used. When the equivalent full-bridge duty cycle is relatively large, the semi-integrated operation mode or the full-integrated operation mode can be used.

[0080] 1 to 6, in one embodiment, when M is 3, the three bridge arm circuits include a first bridge arm switch Q11, a second bridge arm switch Q12, a third bridge arm switch Q21, a fourth bridge arm switch Q22, a fifth bridge arm switch Q31, and a sixth bridge arm switch Q32, where: The first bridge arm switch Q11 and the second bridge arm switch Q12 are connected in series to form a first bridge arm circuit 11, the third bridge arm switch Q21 and the fourth bridge arm switch Q22 are connected in series to form a second bridge arm circuit 12, and the fifth bridge arm switch Q31 and the sixth bridge arm switch Q32 are connected in series to form a third bridge arm circuit 13.

[0081] In an embodiment in which the transformer assembly 20 includes M−1 transformers, when M is 3, the three bridge arm circuits and two transformers form a three-bridge DC-DC converter, and the two transformers are transformers Tx1 and Tx2, respectively. One end of the primary coil of the transformer Tx1 is connected to the bridge arm midpoint of the first bridge arm circuit 11, the other end of the primary coil of the transformer Tx1 is connected to the bridge arm midpoint of the second bridge arm circuit 12, one end of the primary coil of the transformer Tx2 is connected to the bridge arm midpoint of the second bridge arm circuit 12, and the other end of the primary coil of the transformer Tx2 is connected to the bridge arm midpoint of the third bridge arm circuit 13. Each bridge arm switch is turned on or off in response to the high or low level of the received drive signal. Each bridge arm switch may be turned on when it receives a high-level drive signal and turned off when it receives a low-level drive signal, or may be turned on when it receives a low-level drive signal and turned off when it receives a high-level drive signal. In this embodiment, each bridge arm switch is described as turning on when it receives a high-level drive signal and turning off when it receives a low-level drive signal. However, when each bridge arm switching transistor is turned on / off, the primary coil forms a current loop with the connected DC power source via the bridge arm switching transistor that is turned on, causing the current of the connected DC power source to flow through the primary coil, thereby coupling electrical energy to the secondary coil of the transformer assembly 20. The current is then rectified and filtered by the rectifying and filtering circuit 30, converted into a power supply, and output to an electrical load, thereby achieving DC power conversion and isolated output. When M is greater than 3, the M bridge arm circuits and M-1 transformers constitute the transformers of an M-bridge DC-DC converter, in which the bridge arm switch QM1 of the M1 and the bridge arm switch QM2 of the M2 are arranged in series to constitute the Mth bridge arm circuit 1M.

[0082] Referring to Figures 1, 2 and 3, in one embodiment, in the alternating phase-shift full-bridge operation mode, when the main controller controls the two bridge arm switches of the second bridge arm circuit 12 to be turned on / off, the main controller controls the two bridge arm switches of either one of the first bridge arm circuit 11 and the third bridge arm circuit 13 to be turned on / off, and controls the two bridge arm switches of the other bridge arm circuit to be both turned off.

[0083] Referring to Figure 3, Figure 3 is a timing diagram of the drive signals received by each bridge arm switch in the alternating phase-shift full-bridge operation mode. The following analysis is based on the minimum current of inductor L1 being greater than zero.

[0084] In the alternating phase-shifted full-bridge operating mode, the primary sides of the M-1 transformers operate in sequence at the DC power supply voltage and zero voltage over one or more control periods.

[0085] During the first part of a control period, the primary voltage of one of the transformers is the DC power supply voltage, and during the second part of a control period, the primary voltage of this transformer is zero. The transformers operate in this manner for one or more periods. The M-1 transformers cycle in sequence.

[0086] In the alternating phase-shifted full-bridge operation mode, in one control period, one of the transformers is first connected to the DC power supply via the corresponding bridge arm and operates, and then operates with both ends of the transformer short-circuited via the corresponding bridge arm, and the transformer operates in this manner over one or more control periods, and the M-1 transformers operate in a cycle in turn.

[0087] At time t0, the fourth bridge arm switch Q22 and the sixth bridge arm switch Q32 are in the on state, and the remaining bridge arm switches are in the off state. At time t0, the fourth bridge arm switch Q22 is turned off, resonance due to leakage inductance begins, and the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 begins to rise.

[0088] At time t1, the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 reaches its highest point, causing the third bridge arm switch Q21 to soft-turn on. At this time, the primary coil of the transformer Tx2 couples electrical energy to the secondary coil, thereby outputting energy to the outside.

[0089] At time t2, the sixth bridge arm switch Q32 is turned off, and the voltage at the bridge arm midpoint V3 of the third bridge arm circuit 13 starts to rise.

[0090] At time t3, the voltage at the bridge arm midpoint V3 of the third bridge arm circuit 13 reaches its highest point, and the fifth bridge arm switch Q31 is soft-turned on. The transformer Tx2, the third bridge arm switch Q21, and the fifth bridge arm switch Q31 begin to enter a freewheeling state.

[0091] At time t4, the third bridge arm switch Q21 is turned off, resonance due to leakage inductance begins, and the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 begins to decrease.

[0092] At time t5, the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 reaches its lowest point, and the fourth bridge arm switch Q22 is soft-turned on. At this time, the primary coil of the transformer Tx2 couples electrical energy to the secondary coil, thereby outputting energy to the outside.

[0093] At time t6, the fifth bridge arm switch Q31 is turned off, and the voltage at the bridge arm midpoint V3 of the third bridge arm circuit 13 begins to decrease.

[0094] During the freewheeling period of the transformer Tx2, the fourth bridge arm switch Q22, and the sixth bridge arm switch Q32 between times t6 and t7, the sixth bridge arm switch Q32 may or may not activate synchronous rectification. If it is on, Q32 must be turned off by time t8.

[0095] At time t7, the bridge arm midpoint V1 of the first bridge arm circuit 11 automatically reaches the minimum voltage due to the influence of the bridge arm midpoint V2 voltage of the second bridge arm circuit 12 and the bridge arm midpoint V3 voltage of the third bridge arm circuit 13. At this time, the second bridge arm switch Q12 is soft-turned on.

[0096] At time t8, the fourth bridge arm switch Q22 is turned off, resonance due to leakage inductance begins, and the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 begins to rise.

[0097] At time t9, the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 reaches its highest point, causing the third bridge arm switch Q21 to soft turn on. At this time, the primary coil of the transformer Tx1 couples electrical energy to the secondary coil, thereby outputting energy to the outside.

[0098] At time t10, the second bridge arm switch Q12 is turned off, and the voltage at the bridge arm midpoint V1 of the first bridge arm circuit 11 begins to rise.

[0099] At time t11, the voltage at the bridge arm midpoint V1 of the first bridge arm circuit 11 reaches its highest point, causing the third bridge arm switch Q11 to softly turn on. The transformer Tx1, the third bridge arm switch Q21, and the first bridge arm switch Q11 enter a freewheeling state.

[0100] At time t12, the third bridge arm switch Q21 is turned off, resonance due to leakage inductance begins, and the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 begins to decrease.

[0101] At time t13, the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 reaches its lowest point, and the fourth bridge arm switch Q22 is soft-turned on. At this time, the primary coil of the transformer Tx1 couples electrical energy to the secondary coil, thereby outputting energy to the outside.

[0102] At time t14, the first bridge arm switch Q11 is turned off, and the voltage at the bridge arm midpoint V1 of the first bridge arm circuit 11 begins to decrease.

[0103] In the transformer Tx1 between times t14 and t15, during the freewheeling periods of the second bridge arm switch Q12 and the fourth bridge arm switch Q22, the second bridge arm switch Q12 may or may not activate synchronous rectification. If it is on, Q12 must be turned off by time t0.

[0104] At time t15, the bridge arm midpoint V3 of the third bridge arm circuit 13 automatically reaches its minimum voltage due to the influence of the bridge arm midpoint V2 voltage of the second bridge arm circuit 12 and the bridge arm midpoint V1 voltage of the first bridge arm circuit 11. The sixth bridge arm switch Q32 is soft-turned on.

[0105] The periods t0 to t15 are repeated in a cycle.

[0106] If the time acting on transformer Tx2 is longer than the residual magnetism reset time of transformer Tx1, alternating operation can automatically reset the transformer. Other methods (e.g., DC blocking capacitors Cb1 and Cb2, current sampling, etc.) are not required. If the volt-second product change during forward operation of transformer Tx1 is VT1 and the volt-second product change during reverse operation is VT2, the volt-second product of the residual magnetism is (VT1 - VT2). In the case of symmetrical forward and reverse operation, the volt-second product of the residual magnetism (VT1 - VT2) is very small compared to the volt-second product change during forward operation VT1 or the volt-second product change during reverse operation VT2. When transformer Tx2 operates in either the forward or reverse direction, it can reset transformer Tx1 in one direction as long as it exceeds a reasonable time, so transformer Tx1 can always be reset. Similarly, transformer Tx2 can also be reset by transformer Tx1.

[0107] In the above-described embodiment, the period from t0 to t7 is referred to as Phase A. The period from t8 to t15 is referred to as Phase B. The overall operation timing may be an alternating ABAB operation, or an alternating operation consisting of multiple consecutive As followed by multiple Bs. During the period from t0 to t15, while the third bridge arm switch Q21 and the fourth bridge arm switch Q22 are operating, only one pair of switches, either the first bridge arm switch Q11 and the second bridge arm switch Q12 or the fifth bridge arm switch Q31 and the sixth bridge arm switch Q32, is operating, and the remaining pairs are all turned off. Here, bridge arm switch operation refers to turning on and off at a constant duty ratio according to the timing of the drive signal.

[0108] Referring to FIG. 1, FIG. 2 and FIG. 4, in one embodiment, in the dual mode operation mode, the main controller controls the second bridge arm switch Q12 to be turned off first, and then controls the fifth bridge arm switch Q31 to be turned on; controls the first bridge arm switch Q11 to be turned off first, and then controls the sixth bridge arm switch Q32 to be turned on; The main controller controls the second bridge arm switch Q12 to be turned on first, then the sixth bridge arm switch Q32 to be turned off, and controls the first bridge arm switch Q11 to be turned on first, then the fifth bridge arm switch Q31 to be turned off.

[0109] 4, which is a timing diagram of the drive signals received by each bridge arm switch in the dual mode operation mode. The following analysis is based on the situation where the minimum current of inductor L1 is greater than zero.

[0110] In the dual-mode operation mode, the first to (M-1)th transformers operate in sequence at the DC power supply voltage within one control period, and then the (M-1)th transformer is refluxed at zero voltage. In this example, the transformers are counted from right to left, with the first transformer being the illustrated transformer Tx2 and the second transformer being the illustrated transformer Tx1.

[0111] In the dual mode operation mode, when the last transformer is switched to operate, the last two transformers are simultaneously connected to the DC power source and operate.

[0112] In the dual mode operation mode, within one control period, the M-1 transformers start one cycle with any one of them, and are connected to the DC power source through the corresponding bridge arm in order to operate, and after the cycle, the last transformer shorts both ends of the last transformer through the corresponding bridge arm to return current.

[0113] In the dual mode operation mode, when the last transformer is switched on, the last two transformers are simultaneously connected to the DC power source and operate.

[0114] At time t0, the second bridge arm switch Q12 and the fourth bridge arm switch Q22 are turned off, resonance due to leakage inductance begins, and the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 begins to rise.

[0115] At time t1, the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 reaches its highest point, causing the third bridge arm switch Q21 to turn on, and the secondary coil of the transformer Tx2 undergoes rectification and then outputs energy to the outside. At time t2, the second bridge arm switch Q12 is turned on, and the secondary coil of the transformer Tx1 undergoes rectification and outputs energy to the outside.

[0116] At time t3, the sixth bridge arm switch Q32 is turned off. After the sixth bridge arm switch Q32 is turned off, the bridge arm midpoint V3 of the third bridge arm circuit 13 is charged with the residual energy of the leakage inductance and the magnetizing current.

[0117] At time t4, the second bridge arm switch Q12 is turned off.

[0118] At time t5, after passing through one dead zone, the first bridge arm switch Q11 and the fifth bridge arm switch Q31 are turned on, and the transformer Tx1, the first bridge arm switch Q11, and the third bridge arm switch Q21 enter a freewheeling state.

[0119] At time t6, the first bridge arm switch Q11 and the third bridge arm switch Q21 are turned off, resonance due to leakage inductance begins, and the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 begins to decrease.

[0120] At time t7, after the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 reaches its lowest point, the fourth bridge arm switch Q22 is turned on, and the secondary coil of the transformer Tx2 undergoes rectification and then outputs energy to the outside.

[0121] At time t8, the first bridge arm switch Q11 is turned on, and the secondary coil of the transformer Tx1 undergoes rectification and then outputs energy to the outside.

[0122] At time t9, the fifth bridge arm switch Q31 is turned off. After the fifth bridge arm switch Q31 is turned off, the residual energy of the leakage inductance and the magnetizing current are discharged at the bridge arm midpoint V3 of the third bridge arm circuit 13.

[0123] At time t10, the first bridge arm switch Q11 is turned off.

[0124] At time t11, after passing through one dead zone, the second bridge arm switch Q12 and the sixth bridge arm switch Q32 are turned on, and the transformer Tx1, the second bridge arm switch Q12, and the fourth bridge arm switch Q22 enter a freewheeling state.

[0125] The periods t0 to t11 are repeated in a cycle.

[0126] In the above-described embodiment, the main controller controls the timing of the drive signals as described above, and turns them on and off at a constant duty ratio.

[0127] Referring to FIGS. 1, 2, 5 and 6, in one embodiment, in the semi-integrated operation mode or the full-integrated operation mode, the main controller controls the third bridge arm switch Q21 to be turned on first, and then controls the first bridge arm switch Q11 to be turned off, controls the fourth bridge arm switch Q22 to be turned on first, and then controls the second bridge arm switch Q12 to be turned off, The main controller controls the second bridge arm switch Q12 to be turned on first, and then controls the sixth bridge arm switch Q32 to be turned off; controls the first bridge arm switch Q11 to be turned on first, and then controls the fifth bridge arm switch Q31 to be turned off; The main controller controls the fifth bridge arm switch Q31 to be turned on first, then the fourth bridge arm switch Q22 to be turned on, then the sixth bridge arm switch Q32 to be turned on first, then the third bridge arm switch Q22 to be turned on.

[0128] 5, which is a timing diagram of the drive signals received by each bridge arm switch in the semi-integrated operation mode. The following analysis is based on the situation where the minimum current of inductor L1 is greater than zero.

[0129] In the semi-integrated operation mode, the first to (M-1)th transformers are operated in sequence with the DC power supply voltage within one control period, and then (M-1) transformers are operated simultaneously. In this example, the first transformer is the illustrated transformer Tx2, and the second transformer is the illustrated transformer Tx1, counted from right to left.

[0130] In the semi-integrated operation mode, when the last transformer is switched on, the last two transformers are simultaneously connected to the DC power source and operate.

[0131] In the semi-integrated operation mode, within one control period, the M-1 transformers start one cycle from any one of them, and are connected to the DC power source via the corresponding bridge arm in order to operate, and then the M-1 transformers operate simultaneously in series.

[0132] In the semi-integrated operation mode, when the last transformer is switched on, the last two transformers are simultaneously connected to the DC power source and operate.

[0133] At time t0, the third bridge arm switch Q21 is turned on, and Tx2 outputs energy independently after undergoing rectification.

[0134] At time t1, the first bridge arm switch Q11 is turned off and the magnetizing current is discharged to the bridge arm midpoint V1 of the first bridge arm circuit 11.

[0135] At time t2, the second bridge arm switch Q12 is turned on, and in this case, the transformer Tx1 is rectified and then Outside Energy to Tx 2 Starts outputting according to .

[0136] At time t3, the sixth bridge arm switch Q32 is turned off. Between t3 and t4, the leakage inductance residual energy and magnetizing current of Tx1 are used to charge the bridge arm midpoint V3 of the third bridge arm circuit 13, reducing loss when the fifth bridge arm switch Q31 is turned on.

[0137] At time t4, the third bridge arm switch Q21 is turned off. The fifth bridge arm switch Q31 is turned on. Between t4 and t5, the transformers Tx1 and Tx2 undergo rectification and then jointly output energy to the outside.

[0138] At time t5, the fourth bridge arm switch Q22 is turned on, and the transformer Tx2 outputs energy independently after rectification.

[0139] At time t6, the second bridge arm switch Q12 is turned off, and the magnetizing current charges the bridge arm midpoint V1 of the first bridge arm circuit 11.

[0140] At time t7, the first bridge arm switch Q11 is turned on, and the transformer Tx1 is rectified. Outside Energy to Tx 2 Starts outputting according to .

[0141] At time t8, the fifth bridge arm switch Q31 is turned off. During the period from t8 to t9, the leakage inductance residual energy and magnetizing current of the transformer Tx2 are fully utilized to discharge at the bridge arm midpoint V3 of the third bridge arm circuit 13, thereby reducing loss when the sixth bridge arm switch Q32 is turned on.

[0142] At time t9, the fourth bridge arm switch Q22 is turned off. The sixth bridge arm switch Q32 is turned on. Between t9 and t0, the transformers Tx1 and Tx2 undergo rectification and then jointly output energy to the outside.

[0143] The periods t0 to t9 are repeated in a cycle.

[0144] In this mode, Tx2>Tx1> (when Tx1 and Tx2 work together), and the output voltage of the transformer is zero and outputSince there is no current flowing through the feedback circuit, there is no current loss. In the above embodiment, the main controller controls the timing of the drive signal as described above, and turns on / off the drive signal at a constant duty ratio.

[0145] Referring to Figure 6, the DC-DC converter has a full integration mode of operation, and Figure 6 is a timing diagram of the drive signals received by each bridge arm switch in the full integration mode of operation. The following analysis is based on the situation where the minimum current of inductor L1 is greater than zero.

[0146] In the full integrated operation mode, the 1st to (M-1)th transformers are operated in sequence with the DC power supply voltage within one control period.

[0147] In the full-integration operation mode, within one control period, the M-1 transformers start one cycle from any one of the transformers, and are connected to the DC power supply via the corresponding bridge arm in order to operate.

[0148] In the fully integrated operation mode, the control period is adjusted according to the change in the input voltage and the duty ratio of each transformer so that the maximum magnetic flux of any of the M-1 transformers does not exceed the maximum allowable value of the magnetic material, and the control period is decreased as the product of the input voltage and the duty ratio increases to prevent the maximum magnetic flux of the magnetic material from exceeding the allowable value and to prevent magnetic saturation from occurring.

[0149] In the fully integrated operating mode, when the last transformer is switched on, the last two transformers are simultaneously connected to the DC power source and operate.

[0150] At time t0, the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 rises to its highest point, and in response, the third bridge arm switch Q21 is turned on. The transformer Tx2 undergoes rectification and then outputs energy independently.

[0151] At time t1, the first bridge arm switch Q11 is turned off and the magnetizing current is discharged to the bridge arm midpoint V1 of the first bridge arm circuit 11.

[0152] At time t2, the second bridge arm switch Q12 turns on, and the transformer Tx1 goes through rectification. Outside Energy to Tx 2 Starts outputting according to .

[0153] At time t3, the sixth bridge arm switch Q32 is turned off. Between times t3 and t4, the leakage inductance residual energy and magnetizing current of Tx2 are used to the maximum to charge the bridge arm midpoint V3 of the third bridge arm circuit 13, thereby reducing loss when the fifth bridge arm switch Q31 is turned on. The fifth bridge arm switch Q31 is turned on at some time between times t3 and t4.

[0154] At time t4, the third bridge arm switch Q21 is turned off. Resonance begins, and the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 begins to decrease.

[0155] At time t5, the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 drops to its lowest point, and the fourth bridge arm switch Q22 turns on. The transformer Tx2 undergoes rectification and then outputs energy independently.

[0156] At time t6, the second bridge arm switch Q12 is turned off, and the magnetizing current charges the bridge arm midpoint V1 of the first bridge arm circuit 11.

[0157] At time t7, the first bridge arm switch Q11 is turned on, and the transformer Tx1 is rectified. Outside Energy to Tx 2 Starts outputting according to .

[0158] At time t8, the fifth bridge arm switch Q31 is turned off. Between times t8 and t9, the leakage inductance residual energy and magnetizing current of the transformer Tx2 are fully utilized to discharge at the bridge arm midpoint V3 of the third bridge arm circuit 13, thereby reducing loss when the sixth bridge arm switch Q32 is turned on. The sixth bridge arm switch Q32 is turned on at some time between times t8 and t9.

[0159] At time t9, the fourth bridge arm switch Q22 is turned off, resonance begins, and the voltage at the bridge arm midpoint V2 of the second bridge arm circuit 12 begins to rise.

[0160] The periods t0 to t9 are repeated in a cycle.

[0161] In this mode, the transformers Tx2 and Tx1 alternately operate at the DC supply voltages mentioned above, and the output voltage of the transformers is zero and output Since there is no current flowing through the feedback circuit, there is no current loss. In the above embodiment, the main controller controls the timing of the drive signal as described above, and turns on / off the drive signal at a constant duty ratio.

[0162] 1 to 6, in one embodiment, the transformer assembly 20 includes M-1 transformers Tx1 to Tx M-1 The M-1 transformers may include two types of transformers with different turns ratios, each of the transformers including two primary coil connection terminals; one primary coil connection terminal of the Nth transformer is connected to a bridge arm midpoint of the Nth bridge arm circuit, and another primary coil connection terminal of the Nth transformer is both connected to a bridge arm midpoint of the N+1th bridge arm circuit, where 1≦N≦M−1; and the main controller controls on / off of corresponding bridge arm switches in the M bridge arm circuits to operate the transformer assembly 20 in one or a combination of multiple modes: an alternating phase-shifted full-bridge operation mode, a dual-mode operation mode, a semi-integrated operation mode, and a full-integrated operation mode; In an alternating phase-shifted full-bridge operating mode, the primary sides of the M-1 transformers are sequentially operated at the DC power supply voltage and zero voltage for one or more control periods; In the dual mode operation mode, the primary sides of the 1st to (M-1th) transformers operate in sequence with the DC power supply voltage within one control period, and then the (M-1th) transformer is refluxed at zero voltage; In the semi-integrated operation mode, the primary sides of the 1st to (M-1th) transformers are operated in sequence with the DC power supply voltage within one control period, and then the (M-1) transformers are operated simultaneously; In the full integrated operation mode, the primary sides of the 1st to (M-1th) transformers are operated with the DC power supply voltage in sequence within one control period; The DC-DC converter further includes a main controller connected to controlled terminals of bridge arm switches in the M bridge arm circuits, respectively, and configured to operate the transformer assembly in one or a combination of multiple modes of an alternating phase-shifted full-bridge operation mode, a dual-mode operation mode, a semi-integrated operation mode, and a full-integrated operation mode by controlling the on / off of corresponding bridge arm switches in the M bridge arm circuits during operation of the DC-DC converter.

[0163] In the alternating phase-shift full-bridge operation mode, M-1 transformers Tx1 to Tx M-1is combined with M bridge arm circuits 10, and M-1 transformers Tx1 to Tx M-1 are operated in a phase-shifted full-bridge fashion in sequence over one or more control periods. Specifically, within one cycle, the first transformer operates in a phase-shifted full-bridge fashion for one or more control periods, then the second transformer operates for one or more control periods, and so on until the (M-1)th transformer is completed. In the next cycle, the first transformer seamlessly follows the (M-1)th transformer, and so on. In dual-mode operation mode, within one control period, the first through (M-1)th transformers are operated in sequence with the DC power supply voltage, and then the (M-1)th transformer Tx is operated. M-1 In the semi-integrated operation mode, the 1st to M-1th transformers operate in sequence with the DC power supply voltage in one control period, and then the M-1 transformers Tx1 to Tx M-1 In the fully integrated operation mode, the first to (M-1)th transformers operate in sequence with the DC power supply voltage within one control period, and in the next control period, the first transformer begins to operate seamlessly following the (M-1)th transformer, and in the full integrated operation mode, the first to (M-1)th transformers operate in sequence with the DC power supply voltage within one control period, and in the next control period, the first transformer begins to operate seamlessly following the (M-1)th transformer, and in this mode, there is no reflux loss.

[0164] 1 to 6, in the above-described embodiments, when M is 3 or greater in the M-bridge architecture, the DC-DC converter may further include DC blocking capacitors, each connected in series with the primary coil of a transformer requiring magnetic balance. The number of DC blocking capacitors may correspond to the number of transformers. In an embodiment in which the DC-DC converter has M-1 transformers, for example, when M is 3, a DC blocking capacitor may be provided between the bridge arm midpoint V1 of the first bridge arm circuit 11 and one of the primary coil connection terminals of the transformer Tx1, and between the bridge arm midpoint V2 of the second bridge arm circuit 12 and the other of the primary coil connection terminals of the transformer Tx1. Similarly, one DC blocking capacitor may be provided between one of the primary coil connection terminals of the transformer Tx2 and the bridge arm midpoint V2 of the second bridge arm circuit 12, or between the other of the primary coil connection terminals of the transformer Tx2 and the bridge arm midpoint V3 of the third bridge arm circuit 13. The M−1 transformers are connected to the M half bridges with or without DC blocking capacitors.

[0165] The DC-DC converter described in the present application is not limited to the above-mentioned operation modes and specific operation methods of each operation mode. For example, the DC-DC converter in the present application has at least one mode selected from the group consisting of an individual phase-shift full-bridge operation mode, an individual full-bridge operation mode, an alternating full-bridge operation mode, an alternating phase-shift full-bridge operation mode, a dual-mode operation mode, a semi-integrated operation mode, and a full-integrated operation mode; In the individual phase-shifted full-bridge operation mode, only one of the M-1 transformers operates, and in one control period, the transformer is first connected to the DC power source through a corresponding bridge arm and then operates in a manner in which both ends of the transformer are short-circuited through the corresponding bridge arm; In the individual full-bridge operation mode, only one of the M-1 transformers operates, and in one control period, the transformer is first connected to the DC power source through a corresponding bridge arm, and then all bridge arms connected to the transformer are turned off to disconnect the input terminal of the transformer; In the alternating full-bridge operation mode, in one control period, one transformer among the M-1 transformers is first connected to the DC power supply through a corresponding bridge arm, and then the input terminal of the transformer is disconnected by turning off all bridge arms connected to the transformer, and the transformer thus operates over one or more control periods, and the M-1 transformers operate in a cycle in turn; In the alternating phase-shifted full-bridge operation mode, in one control period, one of the transformers is first connected to the DC power source through a corresponding bridge arm and operates, and then both ends of the transformer are short-circuited through a corresponding bridge arm and operates, and the transformer operates in this manner over one or more control periods, and the M-1 transformers operate in a cycle in turn; In the dual mode operation mode, within one control period, one cycle of the M-1 transformers is started from any one of the transformers, and sequentially connected to the DC power source via a corresponding bridge arm to operate; after the cycle, the last one of the transformers is circulated by short-circuiting both ends of the last one of the transformers via a corresponding bridge arm; In the semi-integrated operation mode, within one control period, the M-1 transformers start one cycle from any one of the transformers, and are sequentially connected to the DC power source via corresponding bridge arms to operate; after the cycle, the M-1 transformers operate simultaneously in series; In the total integrated operation mode, within one control period, the M-1 transformers start one cycle from any one of the transformers, and are sequentially connected to the DC power source via corresponding bridge arms to operate; The DC-DC converter further includes a main controller connected to controlled terminals of bridge arm switches in the M bridge arm circuits, respectively, and the main controller is configured to operate the transformer assembly in one or a combination of multiple modes from an individual phase-shifted full-bridge operation mode, an individual full-bridge operation mode, an alternating full-bridge operation mode, an alternating phase-shifted full-bridge operation mode, a dual-mode operation mode, a semi-integrated operation mode, and a full-integrated operation mode by controlling the on / off of corresponding bridge arm switches in the M bridge arm circuits during operation of the DC-DC converter.

[0166] In this example, In the dual mode operation mode, the semi-integrated operation mode, or the fully integrated operation mode, when the last transformer is switched to operate, the last two transformers are simultaneously connected to the DC power source and operate.

[0167] In the fully integrated operation mode, the control period is adjusted according to changes in the input voltage and the duty ratio of each transformer so that the maximum magnetic flux of any of the M-1 transformers does not exceed the maximum allowable value of the magnetic material.

[0168] As the equivalent full-bridge duty ratio changes, switching between any two modes has a hysteresis characteristic of the equivalent full-bridge duty ratio change, where: an equivalent full-bridge duty ratio when switching from the alternating phase-shift full-bridge operation mode to the semi-integrated operation mode is greater than an equivalent full-bridge duty ratio when switching from the semi-integrated operation mode to the alternating phase-shift full-bridge operation mode; an equivalent full-bridge duty ratio when switching from the dual mode operation mode to the semi-integrated operation mode is greater than an equivalent full-bridge duty ratio when switching from the semi-integrated operation mode to the dual mode operation mode; The equivalent full-bridge duty ratio for switching from the semi-integrated to the full-integrated mode of operation is greater than the equivalent full-bridge duty ratio for switching from the full-integrated to the semi-integrated mode of operation.

[0169] The present application further proposes a power supply device including a DC-DC converter as described above.

[0170] For the detailed configuration of this DC-DC converter, please refer to the above embodiments and the description will be omitted here. Since the above DC-DC converter is used in the power supply device of the present application, the power supply device embodiments of the present application include all the technical solutions of all the above DC-DC converter embodiments and achieve the same technical effects, so the description will be omitted here.

[0171] The above description is merely a preferred embodiment of the present application and does not limit the scope of the claims of the present application. Any equivalent structural transformation made using the contents of the specification and accompanying drawings of the present application under the concept of the present invention, or any direct or indirect application to other related technical fields, is also included in the scope of the claims of the present application.

Claims

1. A DC-DC converter, a power supply input terminal to which a DC power supply is connected and configured to operate at a DC power supply voltage; a power output terminal configured to output a power supply; M bridge arm circuits each having an input terminal connected to a power supply input terminal; a transformer assembly including M-1 transformers, the M-1 transformers having at least two different types of turns ratios, each of the transformers including one primary coil and at least one secondary coil, the one primary coil including two primary coil connection terminals, one primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the Nth bridge arm circuit, and the other primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the N+1th bridge arm circuit, wherein 1≦N≦M-1; a rectifier filter circuit having input terminals connected to secondary coil connection terminals of the transformer assembly and output terminals connected to the power supply output terminals, the rectifier filter circuit sharing one common filter inductor; The secondary coil of the transformer assembly has two connection methods, in one connection method, a filtering inductor is connected at a common point after rectification, and in the second connection method, one end of the secondary coil is connected to the filtering inductor at a common point and the other end of the secondary coil is rectified; M bridge arm circuits and the transformer assembly are configured to convert the connected DC power supply into a required voltage in a secondary coil of the transformer assembly, rectify and filter the voltage in the rectifier / filter circuit, and then output the voltage to the power supply output terminal, where M≧3; one transformer operates with the DC power supply voltage to output energy, and when one of the M-1 transformers, at least one end of which is disconnected, starts operating, bridge arm circuits from which magnetizing current flows out in two bridge arms having midpoints connected to primary coil connection terminals of the one transformer turn on lower switches, and bridge arm circuits from which magnetizing current flows in in two bridge arms having midpoints connected to primary coil connection terminals of the one transformer turn on upper switches, so that switching loss in the bridge arm circuits is minimized; or When one transformer operates with the DC power supply voltage and outputs energy, and one of the M-1 transformers, at least one end of which is disconnected, starts operating, the bridge arm circuits from which magnetizing current flows out in two bridge arms whose midpoints are connected to the primary coil connection terminals of the one transformer turn on the lower switches, and the bridge arm circuits from which magnetizing current flows in in two bridge arms whose midpoints are connected to the primary coil connection terminals of the one transformer turn on the upper switches, so that switching loss in the bridge arm circuits is minimized. Another transformer already connected to the DC power supply continues to operate while maintaining the same switch state, so that the two transformers can be connected to the DC power supply simultaneously. DC-DC converter.

2. A DC-DC converter, a power supply input terminal to which a DC power supply is connected and configured to operate at a DC power supply voltage; a power output terminal configured to output a power supply; M bridge arm circuits each having an input terminal connected to a power supply input terminal; a transformer assembly including M-1 transformers, the M-1 transformers having at least two different types of turns ratios, each of the transformers including one primary coil and at least one secondary coil, the one primary coil including two primary coil connection terminals, one primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the Nth bridge arm circuit, and the other primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the N+1th bridge arm circuit, wherein 1≦N≦M-1; a rectifier filter circuit having input terminals connected to secondary coil connection terminals of the transformer assembly and output terminals connected to the power supply output terminals, the rectifier filter circuit sharing one common filter inductor; The secondary coil of the transformer assembly has two connection methods, in one connection method, a filtering inductor is connected at a common point after rectification, and in the second connection method, one end of the secondary coil is connected to the filtering inductor at a common point and the other end of the secondary coil is rectified; M bridge arm circuits and the transformer assembly are configured to convert the connected DC power supply into a required voltage in a secondary coil of the transformer assembly, rectify and filter the voltage in the rectifier / filter circuit, and then output the voltage to the power supply output terminal, where M≧3; the DC-DC converter operates in a semi-integrated mode of operation; In the semi-integrated operation mode, in one control period, the first to (M-1)th transformers are operated in sequence with the DC power supply voltage, and then (M-1) transformers are operated simultaneously; or In the semi-integrated operation mode, within one control period, the M-1 transformers start one cycle from any one of the transformers, and are connected to the DC power source via the corresponding bridge arms in order to operate. After the cycle, the M-1 transformers operate simultaneously in series. DC-DC converter.

3. A DC-DC converter, a power supply input terminal to which a DC power supply is connected and configured to operate at a DC power supply voltage; a power output terminal configured to output a power supply; M bridge arm circuits each having an input terminal connected to a power supply input terminal; a transformer assembly including M-1 transformers, the M-1 transformers having at least two different types of turns ratios, each of the transformers including one primary coil and at least one secondary coil, the one primary coil including two primary coil connection terminals, one primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the Nth bridge arm circuit, and the other primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the N+1th bridge arm circuit, wherein 1≦N≦M-1; a rectifier filter circuit having input terminals connected to secondary coil connection terminals of the transformer assembly and output terminals connected to the power supply output terminals, the rectifier filter circuit sharing one common filter inductor; The secondary coil of the transformer assembly has two connection methods, in one connection method, a filtering inductor is connected at a common point after rectification, and in the second connection method, one end of the secondary coil is connected to the filtering inductor at a common point and the other end of the secondary coil is rectified; M bridge arm circuits and the transformer assembly are configured to convert the connected DC power supply into a required voltage in a secondary coil of the transformer assembly, rectify and filter the voltage in the rectifier / filter circuit, and then output the voltage to the power supply output terminal, where M≧3; the DC-DC converter operates in a fully integrated mode of operation; In the fully integrated operation mode, the first to (M-1)th transformers are operated in sequence with the DC power supply voltage by changing the switching state of the bridge arm circuit shared by two adjacent transformers within one control period, and the states of the two adjacent transformers are changed simultaneously. DC-DC converter.

4. In the fully integrated operation mode, when switching from the (M-1)th transformer to the first transformer, the first transformer is first connected to the DC power supply, and the (M-1)th transformer is turned off with a delay.

4. The DC-DC converter according to claim 3.

5. In the fully integrated operation mode, when M is 3, the second transformer operates with the DC power supply voltage to output energy, and the first bridge arm circuit is in a magnetizing current circulation state of the first transformer, and controls the turn-off of the corresponding switch of this bridge arm circuit, and uses the magnetizing current of the first transformer to charge and discharge the disconnected end.

4. The DC-DC converter according to claim 3.

6. In the total integrated operation mode, the control period is adjusted according to changes in the input voltage and the duty ratio of each transformer.

4. The DC-DC converter according to claim 3.

7. when M is 3, the three bridge arm circuits include a first bridge arm switch, a second bridge arm switch, a third bridge arm switch, a fourth bridge arm switch, a fifth bridge arm switch and a sixth bridge arm switch; the first bridge arm switch and the second bridge arm switch are connected in series to form a first bridge arm circuit; the third bridge arm switch and the fourth bridge arm switch are connected in series to form a second bridge arm circuit; The fifth bridge arm switch and the sixth bridge arm switch are connected in series to form a third bridge arm circuit. In a semi-integrated operation mode, the main controller controls the third bridge arm switch to be turned on first, then the first bridge arm switch to be turned off, then the fourth bridge arm switch to be turned on first, then the second bridge arm switch to be turned off; the main controller controls the second bridge arm switch to be turned on first, and then controls the sixth bridge arm switch to be turned off; the main controller controls the first bridge arm switch to be turned on first, and then controls the fifth bridge arm switch to be turned off; The main controller controls the fifth bridge arm switch to be turned on first, then the fourth bridge arm switch to be turned on, then the sixth bridge arm switch to be turned on first, and then the third bridge arm switch to be turned on.

3. The DC-DC converter according to claim 2.

8. When M is 3, the three bridge arm circuits include a first bridge arm switch, a second bridge arm switch, a third bridge arm switch, a fourth bridge arm switch, a fifth bridge arm switch and a sixth bridge arm switch; the first bridge arm switch and the second bridge arm switch are connected in series to form a first bridge arm circuit; the third bridge arm switch and the fourth bridge arm switch are connected in series to form a second bridge arm circuit; The fifth bridge arm switch and the sixth bridge arm switch are connected in series to form a third bridge arm circuit. In a fully integrated operation mode, the main controller controls the third bridge arm switch to be turned on first, then the first bridge arm switch to be turned off, then the fourth bridge arm switch to be turned on first, then the second bridge arm switch to be turned off; the main controller controls the second bridge arm switch to be turned on first, and then controls the sixth bridge arm switch to be turned off; the main controller controls the first bridge arm switch to be turned on first, and then controls the fifth bridge arm switch to be turned off; The main controller controls the fifth bridge arm switch to be turned on first, then the fourth bridge arm switch to be turned on, then the sixth bridge arm switch to be turned on first, and then the third bridge arm switch to be turned on.

4. The DC-DC converter according to claim 3.

9. A DC-DC converter, a power supply input terminal to which a DC power supply is connected and configured to operate at a DC power supply voltage; a power output terminal configured to output a power supply; M bridge arm circuits each having an input terminal connected to a power supply input terminal; a transformer assembly including M-1 transformers, the M-1 transformers having at least two different types of turns ratios, each of the transformers including one primary coil and at least one secondary coil, the one primary coil including two primary coil connection terminals, one primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the Nth bridge arm circuit, and the other primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the N+1th bridge arm circuit, wherein 1≦N≦M-1; a rectifier filter circuit having input terminals connected to secondary coil connection terminals of the transformer assembly and output terminals connected to the power supply output terminals, the rectifier filter circuit sharing one common filter inductor; The secondary coil of the transformer assembly has two connection methods, in one connection method, a filtering inductor is connected at a common point after rectification, and in the second connection method, one end of the secondary coil is connected to the filtering inductor at a common point and the other end of the secondary coil is rectified; M bridge arm circuits and the transformer assembly are configured to convert the connected DC power supply into a required voltage in a secondary coil of the transformer assembly, rectify and filter the voltage in the rectifier / filter circuit, and then output the voltage to the power supply output terminal, where M≧3; The DC-DC converter operates in a separate phase-shifted full-bridge operating mode; In the individual phase-shifted full-bridge operation mode, within one control period, only one of the M-1 transformers is first operated by connecting to the DC power supply voltage through a corresponding bridge arm, and then both ends of the transformer are short-circuited through the corresponding bridge arm. DC-DC converter.

10. A DC-DC converter, a power supply input terminal to which a DC power supply is connected and configured to operate at a DC power supply voltage; a power output terminal configured to output a power supply; M bridge arm circuits each having an input terminal connected to a power supply input terminal; a transformer assembly including M-1 transformers, the M-1 transformers having at least two different types of turns ratios, each of the transformers including one primary coil and at least one secondary coil, the one primary coil including two primary coil connection terminals, one primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the Nth bridge arm circuit, and the other primary coil connection terminal of the Nth transformer connected to a bridge arm midpoint of the N+1th bridge arm circuit, wherein 1≦N≦M-1; a rectifier filter circuit having input terminals connected to secondary coil connection terminals of the transformer assembly and output terminals connected to the power supply output terminals, the rectifier filter circuit sharing one common filter inductor; The secondary coil of the transformer assembly has two connection methods, in one connection method, a filtering inductor is connected at a common point after rectification, and in the second connection method, one end of the secondary coil is connected to the filtering inductor at a common point and the other end of the secondary coil is rectified; M bridge arm circuits and the transformer assembly are configured to convert the connected DC power supply into a required voltage in a secondary coil of the transformer assembly, rectify and filter the voltage in the rectifier / filter circuit, and then output the voltage to the power supply output terminal, where M≧3; when M is 3, the three bridge arm circuits include a first bridge arm switch, a second bridge arm switch, a third bridge arm switch, a fourth bridge arm switch, a fifth bridge arm switch and a sixth bridge arm switch; the first bridge arm switch and the second bridge arm switch are connected in series to form a first bridge arm circuit; the third bridge arm switch and the fourth bridge arm switch are connected in series to form a second bridge arm circuit; the fifth bridge arm switch and the sixth bridge arm switch are provided in series to form a third bridge arm circuit; During one full cycle, the time advances sequentially from t0 to t9, At time t0, the third bridge arm switch is turned on; At time t1, the first bridge arm switch is turned off; At time t2, the second bridge arm switch is turned on; At time t3, the sixth bridge arm switch is turned off, Between times t3 and t4, the fifth bridge arm switch is turned on; At time t4, the third bridge arm switch is turned off, At time t5, the fourth bridge arm switch is turned on, At time t6, the second bridge arm switch is turned off; At time t7, the first bridge arm switch is turned on, At time t8, the fifth bridge arm switch is turned off, Between times t8 and t9, the sixth bridge arm switch is turned on; At time t9, the fourth bridge arm switch is turned off. DC-DC converter.

11. A DC-DC converter comprising the DC-DC converter according to any one of claims 1 to 10. A power supply device characterized by:

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