Output inductively coupled isop phase-shifted full-bridge converter and phase-shift modulation method

Abstract

The application discloses an output inductance 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 inductances. The application utilizes the coupled output inductance, combines the in-phase mode and the staggered 90-degree mode, and can realize high-efficiency conversion of the converter in a full-load range. In a light load with a small duty cycle, the staggered 90-degree mode is adopted to reduce the circulating current and eliminate the duty cycle loss; as the load is increased, the converter can be switched to the in-phase mode, soft switching can be easily realized, and the efficiency is improved. Therefore, by combining the two modes, the converter proposed by the application can realize low-duty cycle loss and high-efficiency electric energy conversion without additional auxiliary circuits and complex control strategies.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of switching power supply, and particularly relates to an output inductance coupled ISOP phase-shifted full-bridge converter and a phase-shifted modulation method. BACKGROUND

[0002] As an important topology structure in the field of power electronics, the phase-shifted full-bridge (PSFB) converter has been widely used in modern energy conversion scenarios such as new energy systems, electric vehicle power systems and data center power supply architectures, and has been continuously focused by the academic circle. In the operation mechanism of the traditional PSFB converter, the existence of the transformer leakage inductance parameter causes the primary side current to be unable to quickly drop to zero during the phase-shifted regulation process, thereby causing the significant reduction of the effective duty cycle of the secondary side relative to the primary side, i.e. the duty cycle loss. At the same time, the continuous existence of the primary side large current circulation not only hinders the optimization implementation of zero voltage and zero current switching (ZVZCS), but also causes significant conduction loss of the power device. Therefore, how to construct an improved PSFB topology that takes into account the ZVZCS characteristics, suppresses the duty cycle loss, optimizes the current stress distribution and reduces the voltage and current peak values of the device has become a key technical challenge in the field.

[0003] To address the above technical difficulties, recent studies have proposed several innovative solutions. The literature (Y. Gao, Y. Tang, and 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 energy path by connecting a variable inductor network, thereby achieving compensation for the loss of duty cycle. However, such a solution requires the additional design of nonlinear inductor elements and the construction of an auxiliary control loop, significantly increasing system complexity and hindering 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 improved direction adopts a coupled inductor topology architecture, which accelerates the decay of inductor current through the coordinated action of power switching devices and capacitor networks, effectively alleviating the loss of duty cycle. However, this solution has defects such as significant secondary side voltage oscillation, dramatic increase in the number of auxiliary elements, and complex control strategy, which restrict its practical application value.

[0004] In addition, in high-voltage and high-power application scenarios, the input-series output-parallel (ISOP) topology structure is concerned due to its ability to effectively reduce the stress of power devices. To address the limited ZVZCS operating range and duty cycle loss 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.) proposes to inject a compensation current into the half-bridge midpoint using an LC auxiliary network, 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 the double-inductor resonant decoupling rectifier design establishes a separate resonant circuit, achieving a coordinated optimization of the ZVZCS operating mode and duty cycle loss, and demonstrating significant technical advantages. SUMMARY

[0005] To address the large circulating current, narrow soft switching range, and duty cycle loss of traditional phase-shifted full-bridge converters, the present invention proposes an output inductance coupled ISOP phase-shifted full-bridge converter and phase-shifted modulation method. The phase-shift angle between the two phase-shifted full-bridge modules is used to change the equivalent inductance of the output inductor, thereby reducing the circulating current and duty cycle loss and achieving soft switching without the need for additional auxiliary circuits and complex control strategies.

[0006] To achieve the above-mentioned purposes, the technical solutions adopted by the present invention are as follows:

[0007] The output inductively coupled ISOP phase-shifted full-bridge converter is characterized in that it comprises a main circuit, the main circuit comprises a first port, a second port, a phase-shifted full-bridge module, the first port is a power supply end, and the second port corresponds to a load end; the phase-shifted full-bridge module comprises a first phase-shifted full-bridge module and a second phase-shifted full-bridge module, the first phase-shifted full-bridge module comprises switch tubes S1, S2, S3, S4, a first three-winding transformer, rectifier diodes D1, D2, an output filter inductor L o1 , an input filter capacitor C in1 , and a first output filter capacitor, the second phase-shifted full-bridge module comprises switch tubes S3, S4, S5, S6, a second three-winding transformer, rectifier diodes D3, D4, an output filter inductor L o2 , an input filter capacitor C in2 , and a second output filter capacitor, wherein the output filter inductors L o1 and L o2 in the first phase-shifted full-bridge module and the second phase-shifted full-bridge module are coupled to each other, the self-inductance of each is L o1 and L o2 , the mutual inductance is M, and the coupling coefficient between the output filter inductors L o1 and L o2 is k; the switch tubes S1 and S2 form a first bridge arm of the first phase-shifted full-bridge module, the bridge arm midpoint is point A, the switch tubes S3 and S4 form a second bridge arm of the first phase-shifted full-bridge module, the bridge arm midpoint is point B; the switch tubes S5 and S6 form a first bridge arm of the second phase-shifted full-bridge module, the bridge arm midpoint is point C, and the switch tubes S7 and S8 form a second bridge arm of the second phase-shifted full-bridge module, the bridge arm midpoint is point D; the primary winding of the first three-winding transformer and the second three-winding transformer of the first phase-shifted full-bridge module and 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 a rectifier circuit of the first phase-shifted full-bridge module, and the diodes D3 and D4 form a rectifier circuit of the second phase-shifted full-bridge module.

[0008] As a preferred technical scheme of the present application: the output filter inductors L o1 and L o2 of the first phase-shifted full-bridge module and the second phase-shifted full-bridge module are coupled to each other, the currents i o1 and i o2 flowing through the two output filter inductors L o1 and L o2 influence each other due to the magnetic coupling effect, and the change law satisfies:

[0009]

[0010] As a preferred technical scheme of the present application: the switching tubes S1-S8 are switching tubes with existing anti-parallel body diodes and parasitic capacitances of drain-source.

[0011] The phase modulation method of the output inductively coupled ISOP phase-shifted full-bridge converter is characterized by comprising the following steps:

[0012] Step S1, the phase difference between the two phase-shifted full-bridge modules, i.e. 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 in real time between 0° and 90° according to the circuit operation condition, and is switched to 90° when the switching condition is met, and the switching condition is:

[0013]

[0014] Step S2, the first phase-shifted full-bridge module and the second phase-shifted full-bridge module both adopt the phase modulation method, i.e. there is a phase shift between the first bridge arm and the second bridge arm, and the ratio 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 whole period 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, the duty cycle D p is adjusted to adjust the gain of the converter according to the output voltage outer loop; the phase difference is defined as φ ab The phase difference is switched between 0° and 90° according to the load current size.

[0017] As a preferred technical scheme of the present application: since the double-current rectifier circuit is adopted on the secondary side of the two phase-shifted full-bridge modules, the phase difference of the current waveforms on the secondary side is twice the phase difference φ ab of the primary side, i.e. when the primary sides of the two phase-shifted full-bridge modules are staggered by 90°, i.e. φ ab = 90°, the output inductance current flowing through the secondary side will have a phase difference of 180°; when the primary sides are in phase, i.e. φ ab = 0° or are staggered by 180°, i.e. φ ab = 180°, the secondary sides are in phase and have no phase difference, therefore, when the phase difference φ ab = 0° between the two phase-shifted full-bridge modules, the coupling inductance currents are superimposed on each other; when the phase difference φ ab = 90° between the two phase-shifted full-bridge modules, the coupling inductance currents are cancelled out.

[0018] As a preferred technical scheme of the present application: when the output filter inductances L o1 and L o2When magnetic coupling effect occurs, current flows 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 in-phase mode, the winding currents of the first three-winding transformer and the second three-winding transformer are superimposed, and the equivalent inductance increases.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention reduces circulating current and duty cycle loss and achieves soft switching by changing the equivalent inductance value 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, without the need for additional auxiliary circuits and complex control strategies. Attached Figure Description

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

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

[0024] Figure 3 This is a typical operating waveform of the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0026] like Figure 1 As shown, the ISOP phase-shifted full-bridge converter with output inductor coupling proposed in this invention is characterized by including a main circuit, which includes a first port, a second port, and a phase-shifted full-bridge module. The first port is the power supply terminal, and the second port is correspondingly used as the load terminal. 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 switching transistors S1, S2, S3, and S4, a first three-winding transformer, rectifier diodes D1 and D2, and an output filter inductor L. o1 Input filter capacitor C in1 The second phase-shifted full-bridge module includes a first output filter capacitor, and switching transistors S3, S4, S5, and S6, a second three-winding transformer, rectifier diodes D3 and D4, and an output filter inductor L. o2 Input filter capacitor C in2and a second output filter capacitor, wherein the output filter inductors L o1 and L o2 are coupled to each other, and the self-inductance of each of the output filter inductors L o1 and L o2 is L o1 and L o2 , the mutual inductance between the output filter inductors L o1 and L o2 is M, and the coupling coefficient between the output filter inductors L o1 and L o2 is k; the switching tubes S1 and S2 form a first bridge arm of the first phase-shifted full-bridge module, and the midpoint of the bridge arm is point A; the switching tubes S3 and S4 form a second bridge arm of the first phase-shifted full-bridge module, and the midpoint of the bridge arm is point B; the switching tubes S5 and S6 form a first bridge arm of the second phase-shifted full-bridge module, and the midpoint of the bridge arm is point C; the switching tubes S7 and S8 form a 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 and second three-winding transformers of the first and second phase-shifted full-bridge modules are connected to points A and B and points C and D, respectively; the diodes D1 and D2 form a rectifier circuit of the first phase-shifted full-bridge module, and the diodes D3 and D4 form a rectifier circuit of the second phase-shifted full-bridge module.

[0027] The output filter inductors L o1 and L o2 are coupled to each other, and the current i o1 and i o2 flowing through the output filter inductors L o1 and L o2 influence each other due to the magnetic coupling effect, and the variation law satisfies:

[0028]

[0029] The switching tubes S1-S8 are switching tubes with a body diode and a parasitic capacitance between the drain and the source.

[0030] The phase-shifted modulation method of the ISOP phase-shifted full-bridge converter with output inductance coupling provided by the application comprises the following steps:

[0031] Step S1, the phase difference between the two phase-shifted full-bridge modules, i.e., 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 in real time between 0° and 90° according to the operating condition of the circuit, and is switched to 90° when the switching condition is met, and the switching condition is:

[0032]

[0033] Step S2, the first phase-shift full-bridge module and the second phase-shift full-bridge module both adopt the phase-shift modulation method, that is, there is a phase shift between the first bridge arm and the second bridge arm, and the ratio of the time when the upper tube of the first bridge arm and the lower tube of the second bridge arm are turned on to the whole period 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, according to the output voltage outer ring, the duty cycle D is controlled by PI to adjust the gain of the converter p The phase difference is defined as According to the size of the load current, it is switched between 0° and 90°.

[0036] The first phase-shift full-bridge module and the second phase-shift full-bridge module in the application both adopt the phase-shift modulation method, and there is also a phase shift angle between the first phase-shift full-bridge module and the second phase-shift full-bridge module. The primary side duty cycle of the first phase-shift full-bridge module and the second phase-shift full-bridge module is the same, which is represented by D p The phase shift angle between the two phase-shift full-bridge modules is defined as The modulation can be realized by changing the driving signals of the two phase-shift full-bridge modules. For the coupled output inductors L o1 and L o2 , the voltages v Lo1 and v Lo2 across them can be represented as:

[0037]

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

[0039]

[0040] L eq_Lo1 and L eq_Lo2 are related to i o1 and i o2 , and i o1 and i o2 are affected by . As shown in Figure 2 and Figure 3 , when or , i o1 and i o2 ​The same or opposite, therefore, the equivalent inductance expression can be expressed as

[0041]

[0042] Based on the above derivation, in different Different equivalent inductance values ​​can be obtained by varying the values ​​obtained from these values.

[0043] Since both phase-shifted full-bridge modules use current-doubling rectifier circuits on their secondary sides, the phase difference of the secondary side current waveform is equal to the phase difference of the primary side. Twice that, that is, when the primary sides of the two phase-shifting full-bridge modules are staggered by 90°, i.e. The secondary side current flowing through the output inductor will have a 180° phase difference; the primary side current will be in phase, i.e. Or they can be staggered by 180°. During operation, the secondary sides operate in phase with no phase difference. Therefore, the phase difference between the two phase-shifting full-bridge modules is negligible. At this time, the coupled inductor currents are superimposed; the phase difference between the two phase-shifted full-bridge modules At this time, the coupled inductor currents cancel each other out.

[0044] Furthermore, due to the magnetic coupling effect, the currents between the two windings will influence each other, and the interleaved 90° phase modulation will cause i o1 The increase can quickly reduce i o2 Therefore, the primary-side circulating current can be effectively minimized, which helps to eliminate duty cycle losses and achieve zero-current turn-off of the switch, such as... Figure 2 The values ​​[t1, t2] and [t3, t4] are shown in the figure.

[0045] In in-phase mode, the currents between the two windings are superimposed, increasing the equivalent inductance and helping to achieve the converter's ZVS condition. Therefore, the converter can achieve high-efficiency power conversion without additional auxiliary circuitry or complex control strategies. Figure 3 The typical operating waveforms of the converter in in-phase mode are shown. In this mode, the currents between the two windings are superimposed, and the equivalent inductance increases, which helps to achieve the converter's ZVS condition.

[0046] In summary, the ISOP phase-shifted full-bridge converter with output inductance coupling in the embodiment can change the equivalent inductance by simply changing the phase angle between the two phase-shifted full-bridge modules. Combined with the magnetic coupling effect, the output inductor currents can interact and quickly drop to zero, reducing circulating current and duty cycle loss and achieving soft switching. This simplifies the circuit and eliminates the need for additional auxiliary circuits and complex control strategies.

[0047] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any other form, and any modification or equivalent variation made according to the technical essence of the present application still falls within the scope of the present application.

Claims

1. A phase-shift modulation method for an inductively coupled ISOP phase-shifted full-bridge converter, characterized in that, The output inductively coupled ISOP phase-shifted full-bridge converter comprises a main circuit, which comprises a first port, a second port, a phase-shifted full-bridge module, the first port is a power supply end, and the second port corresponds to a load end; the phase-shifted full-bridge module comprises a first phase-shifted full-bridge module and a second phase-shifted full-bridge module, the first phase-shifted full-bridge module comprises switch tubes S1, S2, S3, S4, a first three-winding transformer, rectifier diodes D1 and D2, and an output filter inductor L o1 , an input filter capacitor C in1 , the second phase-shifted full-bridge module comprises switch tubes S5, S6, S7, S 86 , a second three-winding transformer, rectifier diodes D3 and D4, and an output filter inductor L o2 , an input filter capacitor C in2 , wherein the output filter inductors L o1 and L o2 in the first phase-shifted full-bridge module and the second phase-shifted full-bridge module are coupled to each other, the self-inductance is L o1 and L o2 respectively, the mutual inductance is M, and the coupling coefficient between the output filter inductors L o1 and L o2 is k; the switch tubes S1 and S2 constitute a first bridge arm of the first phase-shifted full-bridge module, the bridge arm midpoint is point A, the switch tubes S3 and S4 constitute a second bridge arm of the first phase-shifted full-bridge module, the bridge arm midpoint is point B; the switch tubes S5 and S6 constitute a first bridge arm of the second phase-shifted full-bridge module, the bridge arm midpoint is point C, the switch tubes S7 and S8 constitute a second bridge arm of the second phase-shifted full-bridge module, the bridge arm midpoint is point D; the primary winding of the first three-winding transformer and the second three-winding transformer of the first phase-shifted full-bridge module and 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 constitute a rectifier circuit of the first phase-shifted full-bridge module, the diodes D3 and D4 constitute a rectifier circuit of the second phase-shifted full-bridge module, and the method comprises the following steps: Step S1, the phase difference between the two phase-shifted full-bridge modules, i.e. 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 operating condition of the circuit, and is switched to 90° when the switching condition is met. The switching condition is that: ； Step S2, the first phase-shift full-bridge module and the second phase-shift full-bridge module both adopt a phase-shift modulation method, that is, there is a phase shift between the first bridge arm and the second bridge arm, and the ratio of the time when the upper tube of the first bridge arm and the lower tube of the second bridge arm are turned on to the whole period is defined as the duty cycle D p The duty cycle determines the gain of the converter, and the gain satisfies: ； Step S3, according to the output voltage outer ring adopts PI control duty ratio D p to adjust the converter gain; the phase difference is defined as φ ab Switches between 0° and 90° according to the load current size.

2. The phase-shifted modulation method of the output inductively coupled ISOP phase-shifted full-bridge converter according to claim 1, characterized in that, The output filter inductors L of the first phase-shifted full-bridge module and the second phase-shifted full-bridge module o1 And L o2 Are coupled to each other, and the currents i o1 And L o2 Flowing through the two output filter inductors L o1 And i o2 Will influence each other due to the magnetic coupling effect, and the change law satisfies: 。 3. The phase-shifted modulation method of the output inductively coupled ISOP phase-shifted full-bridge converter according to claim 1, characterized in that, The switch tubes S1-S8 are switch tubes with body diode and parasitic capacitance of drain-source.

4. The phase-shifted modulation method of the output inductively coupled ISOP phase-shifted full-bridge converter according to claim 1, characterized in that, Since both phase-shifted full-bridge modules use current-doubling rectifier circuits on their secondary sides, the phase difference of the secondary side current waveform is equal to the phase difference φ on the primary side. ab Twice that, when the primary sides of the two phase-shifting full-bridge modules are staggered by 90°, i.e., φ ab =90°, the secondary side current flowing through the output inductor will have a 180° phase difference; the primary side is in phase, i.e., φ ab =0° or staggered by 180°, i.e., φ ab When the phase shift is 180°, the secondary side operates in phase with no phase difference. Therefore, the phase difference φ between the two phase-shifted full-bridge modules is... ab At 0°, the coupled inductor currents are superimposed; the phase difference φ between the two phase-shifted full-bridge modules ab When the angle is 90°, the coupled inductor currents cancel each other out.

5. The phase-shifted modulation method of the output inductively coupled ISOP phase-shifted full-bridge converter according to claim 4, characterized in that, When the output filter inductance L o1 and L o2 of the first and second phase-shifted full-bridge modules produce a magnetic coupling effect, the currents flowing through the output filter inductance L o1 and L o2 are i o1 and i o2 , and the currents i o1 and i o2 influence each other.

6. The phase-shifted modulation method of the output inductively coupled ISOP phase-shifted full-bridge converter according to claim 4, characterized in that, In the in-phase mode, the inter-winding currents of the first and second three-winding transformers are superimposed on each other, and the equivalent inductance is increased.

Images