Output inductance coupled ISOP phase-shifted full-bridge converter and phase-shifted modulation method

Abstract

The invention discloses an output inductor coupled ISOP phase-shifted full-bridge converter and a phase-shifted modulation method. The converter comprises two ports, two phase-shifted full-bridge modules and two mutually coupled output inductors. According to the invention, the high-efficiency conversion of the converter in a full-load range can be realized by utilizing the coupling output inductor and combining two kinds of modulation of an in-phase mode and a 90-degree staggered mode. Under a light load with a small duty ratio, a 90-degree staggered mode is adopted to reduce circulating current, and duty ratio loss is eliminated; as the load is increased, the converter can be switched to an in-phase mode, soft switching can be easily realized, and the efficiency is improved. Therefore, by combining the two modes, the converter provided by the invention can realize low duty ratio loss and efficient electric energy conversion of the converter without an additional auxiliary circuit and a complex control strategy.

Description

Technical Field

[0001] The invention belongs to the technical field of switching power supplies, and in particular relates to an ISOP phase-shift full-bridge converter with output inductive coupling and a phase-shift modulation method. Background Art

[0002] Phase-Shifted Full-Bridge (PSFB) converter, as an important topological structure in the field of power electronics, has been widely used in modern energy conversion scenarios such as new energy systems, electric vehicle power systems, and data center energy supply architectures, and continues to receive attention from the academic community. In the operating mechanism of traditional PSFB converters, the existence of transformer leakage inductance parameters causes the primary side current to be unable to quickly drop to zero during the phase shift adjustment process, which in turn causes the effective duty cycle of the secondary side to be significantly reduced relative to the primary side, that is, duty cycle loss. At the same time, the continuous existence of large current circulation on the primary side not only hinders the optimization of zero voltage and zero current switching (Zero-Voltage Zero-Current Switching, ZVZCS), but also causes significant conduction losses in power devices [5]. Therefore, how to construct an improved PSFB topology that takes into account ZVZCS characteristics, suppresses duty cycle losses, optimizes current stress distribution, and reduces device voltage and current peaks has become a key technical challenge in this field.

[0003] In response to the above technical difficulties, recent studies have proposed several innovative solutions. The literature (Y.Gao, Y.Tangand H.Sun et al., "Variable Saturation Inductor-Based Full Bridge Converter with Wide ZVS Range and Reduced Duty Cycle Loss," in IEEE Transactions on Industrial Electronics, vol.69, no.11, pp.11055-11066, Nov.2022.) reconstructs the leakage magnetic energy path by connecting a variable inductor network in series to compensate for the duty cycle loss. However, such solutions require the additional design of nonlinear inductor elements and the construction of auxiliary control loops, which significantly increases the complexity of the system and is not conducive to engineering applications. (G.Liu, B.Wang and F.Liu et al., “An Improved Zero-Voltage and Zero-Current-Switching Phase-Shift Full-Bridge PWM Converter with Low Output Current Ripple,” in IEEE Transactions on Power Electronics, vol. 38, no. 3, pp. 3419-3432, March 2023.) The improvement direction adopts a coupled inductor topology architecture, which accelerates the inductor current decay through the synergy of power switching devices and capacitor networks, thereby effectively alleviating duty cycle losses. However, this solution has defects such as significant secondary side voltage oscillation, a sharp increase in the number of auxiliary components, and a complicated control strategy, which restricts its practical application value.

[0004] In addition, in high-voltage and high-power applications, the Input-Series Output-Parallel (ISOP) topology has attracted much attention because it can effectively reduce the stress of power devices. In view of the limited working range and duty cycle loss of ZVZCS in ISOP-PSFB systems, the literature (Z. Guo, D. Sha and X. Liao et al., “Input-Series-Output-Parallel Phase-Shift Full-Bridge Derived DC–DC Converters with Auxiliary LC Networks to Achieve Wide Zero-Voltage Switching Range,” in IEEE Transactions on Power Electronics, vol. 29, no. 10, pp. 5081-5086, Oct. 2014.) proposed the use of an LC auxiliary network to inject compensation current into the midpoint of the half-bridge, successfully expanding the ZVZCS regulation margin of the lagging bridge arm. In addition, the literature (Z. Pei, D. Guo and T. Cui et al., “Phase-Shift Full-Bridge (PSFB) Converter Integrated Double-Inductor Rectifier with Separated Resonant Circuits (SRCs) for 800-V High-Power Electric Vehicles,” in IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 12, no. 1, pp. 269-282, Feb. 2024.) based on dual-inductor resonant decoupling rectifier design achieves the coordinated optimization of ZVZCS operation mode and duty cycle loss by establishing a separate resonant path, showing significant technical advantages. Summary of the invention

[0005] In order to solve the problems of large circulating current, narrow soft switching range and duty cycle loss in traditional phase-shifted full-bridge converters, the present invention proposes an ISOP phase-shifted full-bridge converter with output inductor coupling and a phase-shift modulation method, which utilizes the phase shift angle between two phase-shifted full-bridge modules to change the equivalent inductance of the output inductor, thereby reducing the circulating current and duty cycle loss and realizing soft switching without the need for additional auxiliary circuits and complex control strategies.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The output inductively coupled ISOP phase-shifted full-bridge converter is characterized in that it includes a main circuit, wherein the main circuit includes a first port, a second port, and a phase-shifted full-bridge module, wherein the first port is a power supply terminal, and the second port is correspondingly used as a load terminal; the phase-shifted full-bridge module includes a first phase-shifted full-bridge module and a second phase-shifted full-bridge module, wherein the first phase-shifted full-bridge module includes a switch tube S 1 , S 2 , S 3 , S 4 , the first three-winding transformer, rectifier diode D 1 , D 2 , output filter inductor L o1 , Input filter capacitor C in1 and a first output filter capacitor, the second phase-shifted full-bridge module includes a switch tube S 3 , S 4 , S 5 , S 6 , the second three-winding transformer, rectifier diode D 3 , D 4 , output filter inductor L o2 , Input filter capacitor C in2 and a second output filter capacitor, wherein the output filter inductor L in the first phase-shifted full-bridge module and the second phase-shifted full-bridge module o1 and L o2 Mutually coupled, their self-inductances are L o1 and L o2 , mutual inductance is M, output filter inductance is L o1 and L o2 The coupling coefficient between the switch tube S is k; 1 and S 2 The first bridge arm of the first phase-shifted full-bridge module is composed of the midpoint of the bridge arm as point A, and the switch tube S 3 and S 4 The second bridge arm of the first phase-shifted full-bridge module is formed, and the midpoint of the bridge arm is point B; the switch tube S 5 and S 6 The first bridge arm of the second phase-shifted full-bridge module is composed of the midpoint of the bridge arm as point C, and the switch tube S 7 and S 8 The second bridge arm of the second phase-shifted full-bridge module is formed, and the midpoint of the bridge arm is point D; the primary windings of the first three-winding transformer of the first phase-shifted full-bridge module and the second three-winding transformer of the second phase-shifted full-bridge module are connected to points A, B and points C, D respectively; the diode D 1 and D 2 The rectifier circuit of the first phase-shifted full-bridge module, diode D 3 and D 4 A rectifier circuit constituting the second phase-shifted full-bridge module.

[0008] As a preferred technical solution of the present invention: the output filter inductor L of the first phase-shift full-bridge module and the second phase-shift full-bridge module o1 and L o2 Mutually coupled, flowing through the two output filter inductors L o1 and L o2 The current i o1 and i o2 They will affect each other due to the magnetic coupling effect, and their changing rules satisfy:

[0009]

[0010] As a preferred technical solution of the present invention: the switch tube S 1 ~S 8 It is a switching tube with an anti-parallel body diode and parasitic capacitance between the drain and source.

[0011] The phase-shift modulation method of the ISOP phase-shift full-bridge converter with output inductor coupling is characterized by comprising the following steps:

[0012] Step S1: The phase difference between the two phase-shifted full-bridge modules, that is, the phase difference between the first bridge arm of the first phase-shifted full-bridge module and the first bridge arm of the second phase-shifted full-bridge module is defined as φ ab The phase difference can be switched between 0° and 90° in real time according to the circuit operating conditions. When the switching conditions are met, it switches to 90°. The switching conditions are:

[0013]

[0014] Step S2: The first phase-shifted full-bridge module and the second phase-shifted full-bridge module both adopt a phase-shifted modulation method, that is, there is a phase shift between the first bridge arm and the second bridge arm, and the proportion of the time when the upper tube of the first bridge arm and the lower tube of the second bridge arm are simultaneously turned on to the entire cycle is defined as the duty cycle D p , the duty cycle determines the gain of the converter, and the gain satisfies:

[0015]

[0016] Step S3: Use PI to control the duty cycle D according to the output voltage outer loop p to adjust the converter gain; the phase difference is defined as φ ab Switches between 0° and 90° depending on the load current.

[0017] As a preferred technical solution of the present invention: Since the secondary sides of the two phase-shifted full-bridge modules both adopt current doubler rectifier circuits, the phase difference of the secondary side current waveform is the primary side phase difference φ ab twice, that is, when the primary sides of the two phase-shifted full-bridge modules are staggered 90°, that is, φ ab=90°, the current flowing through the output inductor on the secondary side will have a phase difference of 180°; the primary side is in phase, that is, φ ab = 0° or staggered 180°, i.e. φ ab =180° operation, the secondary side is in phase operation, there is no phase difference, so the phase difference between the two phase-shifted full-bridge modules is φ ab = 0°, the coupled inductor currents are superimposed on each other; the phase difference between the two phase-shifted full-bridge modules is φ ab When =90°, the coupled inductor currents cancel each other out.

[0018] As a preferred technical solution of the present invention: when the output filter inductor L in the first phase-shift full-bridge module and the second phase-shift full-bridge module o1 and L o2 When the magnetic coupling effect occurs, the current flowing through the output filter inductor L o1 and L o2 The currents are i o1 and i o2 , current i o1 and i o2 They influence each other.

[0019] As a preferred technical solution of the present invention: in the same-phase mode, the inter-winding currents of the first three-winding transformer and the second three-winding transformer are superimposed on each other, and the equivalent inductance increases.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention changes the equivalent inductance of the output inductor by utilizing the phase shift angle between the first phase-shifted full-bridge module and the second phase-shifted full-bridge module, thereby reducing the circulating current and duty cycle loss and realizing soft switching without the need for additional auxiliary circuits and complex control strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the main circuit of the present invention;

[0023] Figure 2 This is the typical working waveform of the present invention.

[0024] Figure 3 This is the typical working waveform of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0026] like Figure 1As shown, the output inductively coupled ISOP phase-shifted full-bridge converter proposed in the present invention is characterized in that it includes a main circuit, the main circuit includes a first port, a second port, and a phase-shifted full-bridge module, the first port is a power supply end, and the second port is correspondingly used as a load end; the phase-shifted full-bridge module includes a first phase-shifted full-bridge module and a second phase-shifted full-bridge module, the first phase-shifted full-bridge module includes a switch tube S 1 , S 2 , S 3 , S 4 , the first three-winding transformer, rectifier diode D 1 , D 2 , output filter inductor L o1 , Input filter capacitor C in1 and a first output filter capacitor, the second phase-shifted full-bridge module includes a switch tube S 3 , S 4 , S 5 , S 6 , the second three-winding transformer, rectifier diode D 3 , D 4 , output filter inductor L o2 , Input filter capacitor C in2 and a second output filter capacitor, wherein the output filter inductor L in the first phase-shifted full-bridge module and the second phase-shifted full-bridge module o1 and L o2 Mutually coupled, their self-inductances are L o1 and L o2 , mutual inductance is M, output filter inductance is L o1 and L o2 The coupling coefficient between the switch tube S is k; 1 and S 2 The first bridge arm of the first phase-shifted full-bridge module is composed of the midpoint of the bridge arm as point A, and the switch tube S 3 and S 4 The second bridge arm of the first phase-shifted full-bridge module is formed, and the midpoint of the bridge arm is point B; the switch tube S 5 and S 6 The first bridge arm of the second phase-shifted full-bridge module is composed of the midpoint of the bridge arm as point C, and the switch tube S 7 and S 8 The second bridge arm of the second phase-shifted full-bridge module is formed, and the midpoint of the bridge arm is point D; the primary windings of the first three-winding transformer of the first phase-shifted full-bridge module and the second three-winding transformer of the second phase-shifted full-bridge module are connected to points A, B and points C, D respectively; the diode D 1 and D 2 The rectifier circuit of the first phase-shifted full-bridge module, diode D 3 and D 4 A rectifier circuit constituting the second phase-shifted full-bridge module.

[0027] The output filter inductor L of the first phase-shifted full-bridge module and the second phase-shifted full-bridge module o1 and L o2 Mutually coupled, flowing through the two output filter inductors L o1 and L o2 The current i o1 and i o2 They will affect each other due to the magnetic coupling effect, and their changing rules satisfy:

[0028]

[0029] The switch tube S 1 ~S 8 It is a switching tube with an anti-parallel body diode and parasitic capacitance between the drain and source.

[0030] The phase-shift modulation method of the ISOP phase-shift full-bridge converter with output inductor coupling proposed by the present invention comprises the following steps:

[0031] Step S1, the phase difference between the two phase-shifted full-bridge modules, that is, the phase difference between the first bridge arm of the first phase-shifted full-bridge module and the first bridge arm of the second phase-shifted full-bridge module is defined as The phase difference can be switched between 0° and 90° in real time according to the circuit operating conditions. When the switching conditions are met, it switches to 90°. The switching conditions are:

[0032]

[0033] Step S2: The first phase-shifted full-bridge module and the second phase-shifted full-bridge module both adopt a phase-shifted modulation method, that is, there is a phase shift between the first bridge arm and the second bridge arm, and the proportion of the time when the upper tube of the first bridge arm and the lower tube of the second bridge arm are simultaneously turned on to the entire cycle is defined as the duty cycle D p , the duty cycle determines the gain of the converter, and the gain satisfies:

[0034]

[0035] Step S3: Use PI to control the duty cycle D according to the output voltage outer loop p to adjust the converter gain; the phase difference is defined as Switches between 0° and 90° depending on the load current.

[0036] The first phase-shifted full-bridge module and the second phase-shifted full-bridge module in the present application both adopt a phase-shifted modulation method, and there is also a phase-shifted angle between the first phase-shifted full-bridge module and the second phase-shifted full-bridge module. The primary side duty ratios of the first phase-shifted full-bridge module and the second phase-shifted full-bridge module are the same, and D p The phase shift angle between two phase-shifted full-bridge modules is defined as The modulation can be achieved by changing the driving signals of the two phase-shifted full-bridge modules. o1 and L o2 , the voltage across its two ends is v Lo1 and v Lo2 It can be expressed as:

[0037]

[0038] Where L eq_Lo1 and L eq_Lo2 Respectively represent the equivalent inductance of the two output inductors after coupling. o1 and i o2 are the currents flowing through the two output inductors. Simplifying, we can get L eq_Lo1 and L eq_Lo2 The expression is

[0039]

[0040] L eq_Lo1 and L eq_Lo2 with i o1 and i o2 Related, and i o1 and i o2 by The impact of Figure 2 and Figure 3 As shown, when or When o1 and i o2 The same or opposite, therefore, the equivalent inductance expression can be expressed as

[0041]

[0042] According to the above derivation, in different Under different conditions, different equivalent inductance values ​​can be obtained.

[0043] Since the secondary sides of the two phase-shifted full-bridge modules both use current doubler rectifier circuits, the phase difference of the secondary side current waveform is equal to the primary side phase difference twice, that is, when the primary sides of the two phase-shifted full-bridge modules are staggered 90°, The current flowing through the output inductor on the secondary side will have a phase difference of 180°; the current on the primary side is in phase, that is, Or staggered 180° During operation, the secondary side operates in phase, with no phase difference. Therefore, the phase difference between the two phase-shifted full-bridge modules is When the coupled inductor currents are superimposed on each other, the phase difference between the two phase-shifted full-bridge modules is , the coupled inductor currents cancel each other out.

[0044] In addition, due to the magnetic coupling effect, the currents in the two windings will affect each other, and the staggered 90° phase modulation makes i o1 The increase in i can quickly reduce o2 , so the primary-side circulating current can be effectively minimized, which helps to eliminate duty cycle loss and achieve zero current shutdown of the switch tube, such as Figure 2 In [t 1 , t 2 ] and [t 3 , t 4 ] as shown.

[0045] In the same-phase mode, the currents between the two windings are superimposed on each other, and the equivalent inductance increases, which helps to achieve the ZVS condition of the converter. Therefore, the converter can achieve efficient power conversion without additional auxiliary circuits and complex control strategies. Figure 3 The typical operating waveform of the converter in the in-phase mode is shown. In this mode, the currents between the two windings are superimposed on each other, and the equivalent inductance increases, which helps to achieve the ZVS condition of the converter.

[0046] In summary, the output inductor coupled ISOP phase-shifted full-bridge converter in the embodiment can change the size of the equivalent inductance only by changing the phase shift angle between the two phase-shifted full-bridge modules. Combined with the magnetic coupling effect, the output inductor currents can affect each other and quickly drop to zero, thereby reducing the circulating current and duty cycle loss and realizing soft switching, simplifying the circuit without the need for additional auxiliary circuits and complex control strategies.

[0047] The above description is only a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. An output inductively coupled ISOP phase-shifted full-bridge converter, characterized in that: It includes a main circuit, the main circuit includes a first port, a second port, and a phase-shifted full-bridge module, the first port is a power supply end, and the second port is correspondingly used as a load end; The phase-shift full-bridge module includes a first phase-shift full-bridge module and a second phase-shift full-bridge module. The first phase-shift full-bridge module includes switch tubes S1, S2, S3, S4, a first three-winding transformer, rectifier diodes D1, D2, an output filter inductor L o1 , Input filter capacitor C in1 and a first output filter capacitor, the second phase-shifted full-bridge module includes switch tubes S3, S4, S5, S6, a second three-winding transformer, rectifier diodes D3, D4, an output filter inductor L o2 , Input filter capacitor C in2 and a second output filter capacitor, wherein the output filter inductor L in the first phase-shifted full-bridge module and the second phase-shifted full-bridge module o1 and L o2 Mutually coupled, their self-inductances are L o1 and L o2 , mutual inductance is M, output filter inductance is L o1 and L o2 The coupling coefficient between them is k; the switch tubes S1 and S2 form the first bridge arm of the first phase-shifted full-bridge module, and the midpoint of the bridge arm is point A; the switch tubes S3 and S4 form the second bridge arm of the first phase-shifted full-bridge module, and the midpoint of the bridge arm is point B; the switch tubes S5 and S6 form the first bridge arm of the second phase-shifted full-bridge module, and the midpoint of the bridge arm is point C; the switch tubes S7 and S8 form the second bridge arm of the second phase-shifted full-bridge module, and the midpoint of the bridge arm is point D; the primary windings of the first three-winding transformer of the first phase-shifted full-bridge module and the second three-winding transformer of the second phase-shifted full-bridge module are connected to points A and B and points C and D respectively; the diodes D1 and D2 form the rectifier circuit of the first phase-shifted full-bridge module, and the diodes D3 and D4 form the rectifier circuit of the second phase-shifted full-bridge module.

2. The output inductively coupled ISOP phase-shifted full-bridge converter according to claim 1, characterized in that: The output filter inductor L of the first phase-shifted full-bridge module and the second phase-shifted full-bridge module o1 and L o2 Mutually coupled, flowing through the two output filter inductors L o1 and L o2 The current i o1 and i o2 They will affect each other due to the magnetic coupling effect, and their changing rules satisfy:

3. The input series output parallel phase-shifted full-bridge converter with coupled output inductance according to claim 1, characterized in that: The switch tubes S1 to S8 are switch tubes having anti-parallel body diodes and parasitic capacitances between drain and source electrodes.

4. The phase-shift modulation method of the output inductively coupled ISOP phase-shift full-bridge converter according to claims 1-3, characterized in that: The steps include: Step S1: The phase difference between the two phase-shifted full-bridge modules, that is, the phase difference between the first bridge arm of the first phase-shifted full-bridge module and the first bridge arm of the second phase-shifted full-bridge module is defined as φ ab The phase difference can be switched between 0° and 90° in real time according to the circuit operating conditions. When the switching conditions are met, it switches to 90°. The switching conditions are: Step S2: The first phase-shifted full-bridge module and the second phase-shifted full-bridge module both adopt a phase-shifted modulation method, that is, there is a phase shift between the first bridge arm and the second bridge arm, and the proportion of the time when the upper tube of the first bridge arm and the lower tube of the second bridge arm are simultaneously turned on to the entire cycle is defined as the duty cycle D p , the duty cycle determines the gain of the converter, and the gain satisfies: Step S3: Use PI to control the duty cycle D according to the output voltage outer loop p to adjust the converter gain; the phase difference is defined as φ ab Switches between 0° and 90° depending on the load current.

5. The phase-shift modulation method of the output inductively coupled ISOP phase-shift full-bridge converter according to claim 4, characterized in that: Since the secondary sides of the two phase-shifted full-bridge modules both use current doubler rectifier circuits, the phase difference of the secondary side current waveform is the primary side phase difference φ ab twice, that is, when the primary sides of the two phase-shifted full-bridge modules are staggered 90°, that is, φ ab =90°, the current flowing through the output inductor on the secondary side will have a phase difference of 180°; the primary side is in phase, that is, φ ab = 0° or staggered 180°, i.e. φ ab =180° operation, the secondary side is in phase operation, there is no phase difference, so the phase difference between the two phase-shifted full-bridge modules is φ ab = 0°, the coupled inductor currents are superimposed on each other; the phase difference between the two phase-shifted full-bridge modules is φ ab When =90°, the coupled inductor currents cancel each other out.

6. The phase-shift modulation method of the output inductor coupled ISOP phase-shift full-bridge converter according to claim 5, characterized in that: When the output filter inductor L in the first phase-shift full-bridge module and the second phase-shift full-bridge module o1 and L o2 When the magnetic coupling effect occurs, the current flowing through the output filter inductor L o1 and L o2 The currents are i o1 and i o2 , current i o1 and i o2 They influence each other.

7. The phase-shift modulation method of the output inductively coupled ISOP phase-shift full-bridge converter according to claim 5, characterized in that: In the same-phase mode, the inter-winding currents of the first three-winding transformer and the second three-winding transformer are superimposed on each other. The equivalent inductance increases.

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