Multi-phase resonant converter

Abstract

The present invention relates to a multi-phase resonant converter, comprising: an input node; an output node; at least two-phase conversion circuits, each phase conversion circuit comprising a resonant circuit connected to the input node and a switching circuit connected between the resonant circuit and the output node, the resonant circuit comprising at least two-stage resonant tanks and multiple switching elements, the switching circuit having a bridge topology composed of multiple power transistors, one end of each stage resonant tank, by means of a corresponding switching element of the multiple switching elements, being connected to a previous stage resonant tank or to the input node, and the other end being directly connected to a corresponding bridge node in the bridge topology; and a control module, which is configured to selectively control the on / off of each power transistor and each switching element in the at least two-phase conversion circuits, so as to achieve a predetermined phase shift between the output signals of the at least two-phase conversion circuit.

Description

[0001] Multi-phase resonant converter

[0002] Technical Field

[0003] The present invention relates to the technical field of voltage conversion, and more specifically to a multi-phase resonant converter.

[0004] Background Art

[0005] In the field of power electronics, non-isolated resonant converters have been widely researched and applied due to their efficient energy conversion capability. Such converters typically use the circuit structure of an LC (inductor-capacitor) resonant tank to achieve zero current or zero voltage switching of power switching devices at specific frequencies. Such a non-isolated resonant converter can perform bi-directional voltage raising / lowering operations between input and output voltages, and is suitable for a variety of power demand scenarios, such as distributed power systems, electric vehicles and renewable energy equipment.

[0006] Existing non-isolated resonant converters usually have a multi-stage LC resonant tank topology, and achieve an output with a voltage reduction ratio of N+1 :1 by means of an N-stage LC resonant tank. Such a design meets the needs of some application scenarios to some extent, but there are still significant limitations. For example, conventional resonant converters mostly employ open loop control, with a fixed ratio relationship (i.e. , gain) between the output voltage and the input voltage, which lacks flexibility and makes it difficult to adapt to variable load and input voltage conditions. In addition, when used in high power applications, the potential to improve the power density of existing converters is limited.

[0007] Summary of the Invention

[0008] The object of the present invention is to overcome the drawbacks of existing non-isolated resonant converters, and propose a new type of multi-phase resonant converter which aims to achieve a higher power density and more flexible output voltage regulation capability by means of an innovative topology and control strategy.

[0009] In particular, the present invention proposes a multi-phase resonant converter, comprising: an input node, which is used for receiving a DC input signal from an external power source; an output node, which is used for outputting an output signal converted by the multi-phase resonant converter; at least two-phase conversion circuits arranged between the input node and the output node, any two-phase conversion circuits of the at least two-phase conversion circuits being connected to each other in parallel, each phase conversion circuit comprising a resonant circuit connected to the input node and a switching circuit connected between the resonant circuit and the output node, the resonant circuit comprising at least two-stage resonant tanks and multiple switching elements, the switching circuit having a bridge topology composed of multiple power transistors, one end of each stage resonant tank, by means of a corresponding switching element of the multiple switching elements, being connected to a previous stage resonant tank or to the input node, and the other end being directly connected to a corresponding bridge node in the bridge topology; and a control module, which is configured to selectively control the on / off of each power transistor and each switching element in the at least two-phase conversion circuits, so as to achieve a predetermined phase shift between the output signals of the at least two-phase conversion circuit.

[0010] According to an optional embodiment, the multi-phase resonant converter comprises N-phase conversion circuits, wherein N is an integer greater than 1 , and the control module is further configured to cause a sequential phase shiift of 36072N between N output signals of the N-phase conversion circuits.

[0011] According to an optional embodiment, the multi-phase resonant converter comprises two-phase conversion circuits, and the control module is further configured to cause a phase shift of 90° between two output signals of the two-phase conversion circuits.

[0012] According to an optional embodiment, the multi-phase resonant converter comprises three-phase conversion circuits, and the control module is further configured to cause a phase shift of 60° between three output signals of the three-phase conversion circuits.

[0013] According to an optional embodiment, the control module is further configured to selectively turn on / off at least one of the multiple switching elements according to a required voltage gain of the multi-phase resonant converter, to turn on / off a corresponding number of resonant tanks.

[0014] According to an optional embodiment, each stage resonant tank of the at least two-stage resonant tanks is formed by a series connection of an inductor and a capacitor.

[0015] According to an optional embodiment, the multi-phase resonant converter is arranged on a PCB, and the inductor in each stage resonant tank is formed by parasitic inductance on the PCB.

[0016] According to an optional embodiment, each phase conversion circuit of the at least two-phase conversion circuits comprises an input capacitor arranged between the input node and the resonant circuit of said phase conversion circuit.

[0017] According to an optional embodiment, the multi-phase resonant converter further comprises an output capacitor arranged between the at least two-phase conversion circuits and the output node.

[0018] The multi-phase resonant converter of the present invention can achieve a number of significant advantages by employing a multi-phase parallel topology design and a phase shift control strategy. First, the resonant converter of the present invention supports a parallel configuration of n-phase conversion circuits, and by shifting each phase by 36072n per stage, can effectively reduce output ripple, thereby maximally limiting a capacitance value of output capacitance; this design significantly improves the power density and overall performance of the converter. In addition, the topology of the present invention allows the parasitic inductance of the PCB board to be used as the resonant inductance, which reduces the reliance on external inductance, simplifying the circuit design, helping to reduce circuit costs and the physical dimensions thereof. Second, the multi-phase resonant converter of the present invention has a flexible gain regulation capability. For example, by turning on or off some LC resonant tanks, the converter can be adapted to different output voltage requirements, allowing the converter to be flexible in responding to input voltage variations and different load conditions.

[0019] Brief Description of the Drawings

[0020] Through the incorporation of the attached drawings hereof and the following specific embodiments which, together with the drawings, are used to illustrate certain principles of the present invention, other features and advantages of the method of the present invention will become clear or illustrated more specifically.

[0021] Fig. 1 shows a topology diagram of a single-phase resonant converter.

[0022] Fig. 2 shows a topology diagram of another single-phase resonant converter.

[0023] Fig. 3 shows a graph of simulation results of the single-phase resonant converter of Fig. 2.

[0024] Fig. 4 shows a topology diagram of a multi-phase resonant converter according to an exemplary embodiment of the present invention.

[0025] Fig. 5 shows a topology diagram of a two-phase three-stage resonant converter according to an exemplary embodiment of the present invention.

[0026] Fig. 6 shows a graph of simulation results of the two-phase three-stage resonant converter of Fig. 5. Fig. 7 shows a topology diagram of a three-phase three-stage resonant converter according to an exemplary embodiment of the present invention.

[0027] Fig. 8 shows a graph of simulation results of the three-phase three-stage resonant converter of Fig. 7.

[0028] Detailed Description of the Invention

[0029] The multi-phase resonant converter according to the present invention is described below through embodiments with reference to the drawings. Many specific details are expounded in the description below, to give those skilled in the art a more comprehensive understanding of the present invention. However, it will be obvious to those skilled in the art that the invention can be realized without some of these specific details. On the contrary, one may consider using any combination of the features and key elements below to implement the present invention, regardless of whether they relate to different embodiments. Therefore, the various aspects, features, embodiments and advantages below merely serve an illustrative purpose, and should not be regarded as key elements or definitions of the claims.

[0030] Fig. 1 shows a topology diagram of a single-phase resonant converter. The resonant converter contains two-stage LC resonant tanks (i.e. L1 C1 and L2C2); by periodically controlling the activation time of the two-stage resonant tanks, it is possible to produce a voltage reduction of an input voltage Vin to an output voltage Vout, and for the two-stage LC resonant tank structure, a fixed voltage reduction ratio Vin: Vout = 3:1 can be achieved.

[0031] Fig. 2 shows a topology diagram of another single-phase resonant converter. The resonant converter contains three-stage LC resonant tanks (i.e. L1 C1 , L2C2 and L3C3); by periodically controlling the activation time of the three-stage resonant tanks, it is possible to produce a voltage reduction of an input voltage Vin to an output voltage Vout, and for the three-stage LC resonant tank structure, a fixed voltage reduction ratio Vin:Vout = 4:1 can be achieved.

[0032] Fig. 3 shows a graph of simulation results of the single-phase resonant converter of Fig. 2. This simulation takes a three-stage resonant tank voltage reduction as an example, assuming a single-phase power of 500 W, an input voltage Vin of 48 V, an output current of lout, an output voltage Vout of 12 V, a switching frequency equal to a resonant tank resonant frequency of 300 kHz, and a duty cycle of 50%. As can be seen from Fig. 3, the ripple signal in the output current lout and the output voltage Vout is large; assuming that an output voltage ripple requirement of 0.15 V must be met, an output capacitor Cout configured at 100 uf is required.

[0033] It can be seen that such a conventional single-phase resonant converter has significant drawbacks. Firstly, such a single-phase resonant converter employs an open loop control strategy, which limits a regulation range of the output voltage, such that when there are fluctuating input voltages or varying load demands, it is difficult to synchronously achieve different voltage reduction ratios. Secondly, it is difficult to increase the power density of such a converter in high power applications. In addition, in order to achieve a higher voltage reduction ratio or to further increase power density in high power applications, existing converters require the addition of additional circuit components, which not only increases the cost, but also makes the circuit more complex and bulky.

[0034] In response to these deficiencies, the present invention proposes a new type of multi-phase resonant converter which aims to overcome the limitations present in existing single-phase resonant converters by means of an innovative topology and control strategy, achieving a higher power density and more flexible output voltage regulation capability.

[0035] Fig. 4 shows a topology diagram of a multi-phase resonant converter according to an exemplary embodiment of the present invention. As shown in Fig. 4, the multi-phase resonant converter first comprises an input node and an output node, wherein the input node is used for receiving an input signal Vin provided by an external power source, and the output node is used for outputting a converted output signal Vout.

[0036] The resonant converter may be formed by connecting in parallel multi-phase conversion circuits PH1 -PHn that are arranged between the input node and the output node. Each phase conversion circuit comprises a resonant circuit and a switching circuit, wherein the resonant circuit is connected to the input node, and is composed of multi-stage resonant tanks (e.g. LC resonant tanks) and multiple switching elements. The switching circuit is connected between the resonant circuit and the output node, in a bridge topology consisting of multiple power transistors. For example, the bridge topology comprises half-bridges, each half-bridge consisting of two power transistors: an upper one and a lower one.

[0037] The resonant circuit in each phase conversion circuit comprises multi-stage / at least two-stage resonant tanks, each stage resonant tank being formed by connecting in series an inductor (e.g. L1 ) and a capacitor (e.g. C1 ). One end of each stage resonant tank is connected to the previous stage resonant tank or the input node by means of a switching element, and the other end is connected directly to the corresponding bridge node in the bridge topology. Therefore, it will be understood that the number of half-bridges in the switching circuit (i.e. , the number of phases of the switching circuit) depends on the number of stages of resonant tanks. As an example, assume that a certain conversion circuit contains three-stage resonant tanks: the switching circuit in this conversion circuit correspondingly also has a three-phase half-bridge topology, so that the bridge node of each phase half-bridge is connected to a corresponding resonant tank.

[0038] Multiple power transistors forming a bridge topology may be selectively turned on or off under the control of a control module to achieve corresponding energy conversion between the input node and the output node. The control module is a core part of the multi-phase resonant converter, and is responsible for selectively controlling the on / off of the power transistors and switching elements in the respective phase conversion circuit. With precise time control, the control module enables phase shift between the output signals of each phase, thereby reducing the overall output voltage ripple of the converter and improving the power conversion efficiency of the converter.

[0039] As shown in Figure 4, assuming that the multi-phase resonant converter comprises N-phase conversion circuits (N is an integer greater than 1 ), in order to minimize the output voltage ripple, it is possible to cause a sequential phase shift of 36072N between N output signals of the N-phase conversion circuits. For example, to achieve phase shifting, the control module may output PWM gating signals of different phases to the respective phase converters, and these gating signals are 36072N out of phase.

[0040] In addition, the control module is further configured to selectively control the on / off of at least one of the multiple switching elements according to a required voltage gain of the multi-phase resonant converter, to turn on / off a corresponding number of resonant tanks. Specifically, the control module automatically adjusts the state of the switching element by receiving a voltage gain demand signal, thereby controlling a specific number of resonant tanks to turn on / off. For example, if an increase in voltage gain is required, the control module will turn on additional switching elements to activate more resonant tanks; conversely, if a decrease in voltage gain is required, then corresponding switching elements are disconnected to turn off some resonant tanks.

[0041] The multi-phase resonant converter may be disposed on a PCB, wherein the inductor in each stage resonant tank can be implemented using a parasitic inductance on the PCB, which reduces the need for external inductive elements and reduces system cost and complexity.

[0042] Each phase conversion circuit may include an input capacitor disposed between an input node and a resonant circuit of said phase conversion circuit. In Fig. 4, the input capacitors are labeled Cin1 , Cin2... Cinn , where n represents the number of phases. These input capacitors can smooth the input signal Vin, reducing ripple in the input signal Vin, while providing a stable initial voltage to the resonant circuit.

[0043] The multi-phase resonant converter further comprises an output capacitor Cout disposed between the multi-phase conversion circuit and the output node. The function of the output capacitor Cout is to further smooth the output voltage, reduce the voltage ripple at the output end, and improve the output quality of the power source. In a multi-phase configuration, the output capacitor can also help balance the load between the phases, ensuring stability and uniformity of the output. Fig. 5 shows a topology diagram of a two-phase three-stage resonant converter according to an exemplary embodiment of the present invention. As shown in Fig. 5, the resonant converter is formed by two-phase conversion circuits PH1 , PH2 connected in parallel, each phase conversion circuit comprising three-stage LC resonant tanks L1 C1 , L2C2, L3C3. Each stage resonant tank consists of an inductor and a capacitor connected in series. Output currents of output circuits of these two-phase conversion circuits are assumed to be 11 , I2, respectively, wherein lout is the total output current of these two-phase converters. In order to achieve a minimization of ripple in the total output current lout and the corresponding total output voltage Vout, two-phase PWM control signals can be respectively supplied to the two-phase conversion circuits by means of a control module, the two-phase PWM control signals being 90° out of phase, so that the two output signals 11 , I2 of the two-phase conversion circuits are likewise 90° out of phase, the two output signals 11 , I2 being superimposed on each other at the total output end, and the amplitudes canceling each other, thereby minimizing ripple in the total output signals lout, Vout.

[0044] Fig. 6 shows a graph of simulation results of the two-phase three-stage resonant converter of Fig. 5. This simulation takes a three-stage resonant tank voltage reduction as an example, assuming a dual-phase power of 1000 W, an output ripple voltage requirement of 0.15 V, a switching frequency equal to a resonant tank resonant frequency of 300 kHz, and a duty cycle of 50%. As shown in Fig. 6, by shifting the phase of two-phase output currents 11 and I2 by 90° (36072*2), the ripple in the total output current lout and the total output voltage Vout can be significantly reduced, and in this case an output capacitor Cout of 25 uF capacitance meets the output voltage ripple requirement of 0.15 V.

[0045] Fig. 7 shows a topology diagram of a three-phase three-stage resonant converter according to an exemplary embodiment of the present invention. As shown in Fig. 7, the resonant converter is formed by three-phase conversion circuits PH1 , PH2, PH3 connected in parallel, each phase conversion circuit comprising three-stage LC resonant tanks L1 C1 , L2C2, L3C3. Output currents of output circuits of these two-phase conversion circuits are assumed to be 11 , I2, respectively, wherein lout is the total output current of these two-phase converters. In order to achieve a minimization of ripple in the total output current lout and the corresponding total output voltage Vout, three-phase PWM control signals can be respectively supplied to the three-phase conversion circuits by means of a control module, the three-phase PWM control signals being 60° out of phase, so that three output signals 11 , I2, I3 of the three-phase conversion circuits are likewise 60° out of phase, the three output signals being superimposed on each other at the total output end, and the amplitudes canceling each other, thereby minimizing ripple in the total output signals lout, Vout.

[0046] Fig. 8 shows a graph of simulation results of the three-phase three-stage resonant converter of Fig. 7. This simulation takes a three-stage resonant tank voltage reduction as an example, assuming a three-phase power of 1500 W, an output ripple voltage requirement of 0.15 V, a switching frequency equal to a resonant tank resonant frequency of 300 kHz, and a duty cycle of 50%. As shown in Fig. 8, by shifting the phase between three-phase output currents 11 and I2 by 60° (36073*2), the ripple in the total output current lout and the total output voltage Vout can be significantly reduced, and in this case an output capacitor Cout of 25 uF capacitance meets the output voltage ripple requirement of 0.15 V.

[0047] The above simulations and experiments demonstrate the high performance achievable by the resonant converter of the present invention. For example, in a single-phase 500 W configuration, a stable output of 12 V can be achieved at a 48 V input voltage. In the dual-phase 1000 W and three-phase 1500 W configurations, a multi-phase parallel topology design can be used to maintain output ripple voltages as low as 0.15 V. Simulation results show that the multi-phase resonant converter of the present invention has a good load regulation capability and ripple suppression capability, and has a flexible gain regulation capability, and is suitable for high performance power source conversion applications.

[0048] The multi-phase resonant converter of the present invention can achieve a number of significant advantages by employing a multi-phase parallel topology design and a phase shift control strategy. First, the resonant converter of the present invention supports a parallel configuration of n-phase conversion circuits, and by shifting each phase by 36072n per stage, can effectively reduce output ripple, thereby maximally limiting a capacitance value of output capacitance; this design significantly improves the power density and overall performance of the converter. In addition, the topology of the present invention allows the parasitic inductance of the PCB board to be used as the resonant inductance, which reduces the reliance on external inductance, simplifying the circuit design, helping to reduce circuit costs and the physical dimensions thereof. Second, the multi-phase resonant converter of the present invention has a flexible gain regulation capability. For example, by turning on or off some LC resonant tanks, the converter can be adapted to different output voltage requirements, allowing the converter to be flexible in responding to input voltage variations and different load conditions.

[0049] Although the present invention has been disclosed above through preferred embodiments, the present invention is not limited to this. Various changes and modifications made by a person skilled in the art without departing from the spirit and scope of the present invention should be included in the scope of protection thereof. Thus, the scope of protection of the present invention shall be the scope defined by the claims.

Claims

Claims1. A multi-phase resonant converter, wherein the multi-phase resonant converter comprises: an input node, which is used for receiving a DC input signal (Vin) from an external power source; an output node, which is used for outputting an output signal (Vout) converted by the multi-phase resonant converter; at least two-phase conversion circuits (PH1 -PHn) arranged between the input node and the output node, any two-phase conversion circuits of the at least two-phase conversion circuits being connected to each other in parallel, each phase conversion circuit comprising a resonant circuit connected to the input node and a switching circuit connected between the resonant circuit and the output node, the resonant circuit comprising at least two-stage resonant tanks and multiple switching elements, the switching circuit having a bridge topology composed of multiple power transistors, one end of each stage resonant tank, by means of a corresponding switching element of the multiple switching elements, being connected to a previous stage resonant tank or to the input node, and the other end being directly connected to a corresponding bridge node in the bridge topology; and a control module, which is configured to selectively control the on / off of each power transistor and each switching element in the at least two-phase conversion circuits (PH1 -PHn), so as to achieve a predetermined phase shift between the output signals of the at least two-phase conversion circuit.

2. The multi-phase resonant converter as claimed in claim 1 , wherein the multi-phase resonant converter comprises N-phase conversion circuits, wherein N is an integer greater than 1 , and the control module is further configured to cause a sequential phase shift of 36072N between N output signals of the N-phase conversion circuits.

3. The multi-phase resonant converter as claimed in claim 1 or 2, wherein the multi-phase resonant converter comprises two-phase conversion circuits, and the control module is further configured to cause a phase shift of 90° between two output signals of the two-phase conversion circuits.

4. The multi-phase resonant converter as claimed in claim 1 or 2, wherein the multi-phase resonant converter comprises three-phase conversion circuits, and the control module is further configured to cause a phase shift of 60° between three output signals of the three-phase conversion circuits.

5. The multi-phase resonant converter as claimed in claim 1 or 2, wherein the control module is further configured to selectively turn on / off at least one of the multiple switching elements according to a required voltage gain of the multi-phase resonant converter, to turn on / off a corresponding number of resonant tanks.

6. The multi-phase resonant converter as claimed in claim 1 or 2, wherein each stage resonant tank of the at least two-stage resonant tanks is formed by a series connection of an inductor and a capacitor.

7. The multi-phase resonant converter as claimed in claim 6, wherein the multi-phase resonant converter is arranged on a PCB, and the inductor in each stage resonant tank is formed by parasitic inductance on the PCB.

8. The multi-phase resonant converter as claimed in claim 1 or 2, wherein each phase conversion circuit of the at least two-phase conversion circuits comprises an input capacitor (Cin1 -Cinn) arranged between the input node and the resonant circuit of said phase conversion circuit.

9. The multi-phase resonant converter as claimed in claim 1 or 2, wherein the multi-phase resonant converter further comprises an output capacitor (Cout) arranged between the at least two-phase conversion circuits and the output node.

Images