Multi-channel weak-coupling wide voltage output dc-dc converter based on zero voltage switching

Abstract

The application discloses a multi-path weak coupling wide voltage output DC-DC converter based on zero voltage switching, which comprises a direct current input power supply V in and N output branches, wherein N is a positive integer and N is greater than or equal to 2; the multi-path weak coupling wide voltage output DC-DC converter can realize good cross regulation among output ports by using a small number of elements, can realize both step-up output and step-down output, can meet different voltage demands, has a wide output voltage range, is easy to realize zero voltage switching, and thus can ensure high system efficiency; the multi-path output voltages can be respectively adjusted by independent control variables, and the cross coupling effect among the multiple output ports is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of power electronics, and relates to power conversion technology, in particular to a multi-output weakly coupled wide voltage output DC-DC converter based on zero voltage switching. BACKGROUND

[0002] Compared with traditional power electronic converters, multi-output DC-DC converters have the advantages of low cost, small size and weight, and compact structure, and have been widely used in electric vehicles, portable electronic devices, LED drivers and other fields. Among them, a relatively convenient and low-cost solution to achieve multi-output is the single inductor multiple output (SIMO) converter. However, there is often a serious cross-coupling problem between the multiple output ports of the SIMO converter, which endangers the stable operation of the system. Although other solutions can be taken to reduce the influence of cross-coupling effect, it undoubtedly increases the complexity of the system and brings defects in system performance. As the foundation of the entire power conversion system, the structure of the circuit topology is crucial to the multi-output converter, so it is imperative to study new topologies of reliable multi-output converters. SUMMARY

[0003] In order to overcome the shortcomings of the prior art, the present application provides a multi-output weakly coupled wide voltage output DC-DC converter based on zero voltage switching, which realizes good cross-regulation between output ports with fewer component counts, can meet the wide output voltage range of different voltage requirements, and is easy to realize zero voltage switching to improve system efficiency.

[0004] The technical scheme adopted by the present application is:

[0005] The multi-output weakly coupled wide voltage output DC-DC converter based on zero voltage switching comprises a DC input power supply V in and N output branches, N is a positive integer and N≥2;

[0006] The input power supply V in is connected to the source electrode of the first output branch switch tube S1 after connecting the inductor L1, the capacitor C1, the diode D and the capacitor C2 in the first output branch are connected in series and then connected in parallel between the source electrode of the switch tube S1 and the ground, the inductor L2 is connected in parallel between the diode D and the capacitor C2, and the load R1 is connected in parallel with the capacitor C2;

[0007] The inductor L i+1 , the capacitor C i+1 and the load R i in the remaining i output branch are connected in series and then connected in parallel between the source electrode of the switch tube S i and the ground, the source electrode of the switch tube S i is connected to the source electrode of the switch tube Si-1 Drain connected, S i Drain and input power V in Common ground, i∈[2, N].

[0008] Further, there are N+1 working modes in each switching cycle, and there are N duty cycles D1, D2, …, DN+1. N The output voltage V o1 , V o2 , …, V oN of each output branch can be adjusted by adjusting the size of the corresponding duty cycle.

[0009] Further, the switch tubes S1, S2, …, SN+1 N Use STP75NF75MOS tube.

[0010] Further, the switch tubes S1, S2, …, SN+1 N Use TMS320F28335 type digital signal processor to generate driving signal for driving, and the gate-source voltage of the switch tube is between-5V and 20V.

[0011] Compared with the prior art, the present application has the following advantages:

[0012] (1) The multi-output DC-DC converter of the present application adopts a new type of multi-output converter topology, which realizes good cross regulation between output ports with fewer components, can realize both step-up output and step-down output, can meet different voltage requirements, and has a wide output voltage range.

[0013] (2) The multi-output DC-DC converter of the present application is easy to realize zero voltage switching (ZVS), thereby ensuring high system efficiency.

[0014] (3) The multi-output voltage of the present application can be adjusted by independent control variables, effectively reducing the cross-coupling effect between multiple output ports.

[0015] (4) The circuit elements used in the present application have the characteristics of small size, simple structure, simple control and low cost. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is the topology structure diagram of N-way multi-output weak coupling wide voltage output DC-DC converter

[0017] Figure 2 It is the driving signal diagram of N-way multi-output weak coupling wide voltage output DC-DC converter

[0018] Figure 3 It is the topology structure diagram of double-output DC-DC converter

[0019] Figures 4a-4c The circuit modal diagram of a dual-output DC-DC converter in one switching cycle

[0020] Figure 5 The main waveform diagram of the dual-output DC-DC converter

[0021] Figure 6 The experimental waveforms of gate-source voltage and inductor current are shown in Figure 2.

[0022] Figure 7 Experimental waveforms of gate-source voltage and drain-source current

[0023] Figure 8 The experimental waveforms of the gate-source voltage, drain-source voltage, and drain-source current of the switch tube S2 are shown in Figure 2.

[0024] Figure 9 A partial enlarged view of the conduction process of the switch tube S2

[0025] Figure 10 Efficiency test curve of the dual-output DC-DC converter experimental prototype DETAILED DESCRIPTION

[0026] In order to more clearly understand the technical content of the present invention, the present invention is further described with reference to the accompanying drawings in the embodiments of the present invention.

[0027] The structure and working principle of the present invention will be described below with reference to the accompanying drawings.

[0028] The topology of the multi-channel weakly coupled wide voltage output DC-DC converter of the present invention is as follows: Figure 1 As shown, it specifically includes a DC input power supply V in , N-way DC load R1, R2, ..., R N , N switching tubes S1, S2, ..., S N , N+1 inductors L1, L2, ..., L N 、L N+1 , N+1 capacitors C1, C2, ..., C N 、C N+1 and a diode D. Wherein, N is a positive integer and N≥2.

[0029] The specific connection mode of the multi-output converter of the present invention is: input power supply V in After connecting the inductor L1, it is connected to the source of the switch tube S1. In the first output branch, the capacitor C1, diode D, and capacitor C2 are connected in series and then connected in parallel between the source of the switch tube S1 and the ground. The inductor L2 is connected in parallel between the diode D and capacitor C2. The load R1 is connected in parallel with capacitor C2.

[0030] The inductance L in the other i-th output branchi+1 With capacitor C i+1 and its parallel load R i After connecting in series, connect in parallel to the switch tube S i Between the source and the ground, the switch tube S i Source and switch tube S i-1 Drain connection, S i Drain and input power supply V in Common ground, i∈[2,N].

[0031] like Figure 2 As shown, the N-way multi-output DC-DC converter has N+1 operating modes in each switching cycle, and there are N duty cycles D1, D2, ..., D N The output voltage V of each branch can be adjusted by adjusting the corresponding duty cycle o1 、V o2 ,…,V oN .

[0032] Furthermore, at time t0, when switch S2 is turned on, its drain-source current (i ds2 ) is converted from an anti-parallel diode to a MOSFET. Therefore, there is no reverse recovery process, thus achieving ZVS. Furthermore, in this operating mode, S2 functions as a synchronous rectification switch. Both of these features reduce switching losses and help improve converter efficiency.

[0033] like Figure 3 As shown, the working principle of the converter proposed in the present invention is analyzed in detail by taking a dual-output DC-DC converter as an example. To simplify the analysis process, it is assumed that all components are ideal devices and the inductor current operates in continuous conduction mode (CCM). Figures 4a-4c The circuit equivalent diagram of the three operating modes of the dual-output DC-DC converter in one switching cycle. Figure 5 The main waveform diagram.

[0034] Working principle analysis:

[0035] Mode 1 [t0~t1]: At t0, switch S1 is off, S2 is on, and diode D is on. Inductors L1, L2, and L3 all release energy, and the current i across the inductor is L1 、i L2 and i L3 Linearly decreases. Therefore, the state equation of the system is:

[0036]

[0037] Mode 2 [t1~t2]: At t1, switch S1 is turned on, S2 remains on, and diode D is reverse biased. Input power supply V inand capacitor C1 provide energy for inductors L1 and L2, respectively, and the current i L1 and i L2 linearly increases, inductor L3 provides energy for the load, and the current i L3 linearly decreases. Therefore, the state equation of the system is:

[0038]

[0039] Mode 3 [t2-t3]: at time t2, switch S2 is turned off, S1 remains on, and diode D is turned on. Both inductors L1 and L2 release energy, and the current i L1 and i L2 linearly decreases, inductor L3 stores energy, and the current i L3 linearly increases. Therefore, the state equation of the system is:

[0040]

[0041] Through the above analysis, it can be known from the volt-second balance principle of inductors that:

[0042] V C1 = V in (4)

[0043]

[0044]

[0045] wherein M1 and M2 are voltage gains of the two output branches, respectively.

[0046] According to formula (5), for the first output branch, the output voltage V o1 may be higher or lower than the input voltage V in by adjusting the duty cycle D1, which means that the converter has a wide output voltage range. According to formula (6), for the second output branch, the output voltage V o2 is lower than the input voltage V in . Since the two output voltages can be adjusted by two independent control variables D1 and D2, respectively, good cross-regulation can be achieved by a simple control scheme.

[0047] Further, on the basis of the above analysis, an experimental prototype of the dual-output DC-DC converter is built. The parameters of the experimental prototype of the dual-output DC-DC converter are shown in Table 1.

[0048] Table 1 Parameters of experimental prototype of dual-output DC-DC converter

[0049] Variable Value / Model in ]]> ​ 20V Output voltage V o1 , V o2 ]] 24V, 12V Frequency f 20 kHz Power P 50W capacitors C1, C2, C3 47 μF, 100 μF, 100 μF inductances L1, L2, L3 1 mH, 1 mH, 470 μH switches S1, S2 STP75NF75 Diode D MBR20200

[0050] Wherein, the driving signal is generated by using a TMS320F28335 type digital signal processor, the gate-source voltage (V GS ) of the switch tube MOSFET varies between -5V and 20V, which can effectively control the off and on of the switch tube. Figure 6 is an experimental waveform diagram of the gate-source voltage and the inductor current; Figure 7 is an experimental waveform diagram of the gate-source voltage and the drain-source current; Figure 8 is an experimental waveform diagram of the gate-source voltage, the drain-source voltage and the drain-source current of the switch tube S2; Figure 9 is a partial enlarged view of the on process of the switch tube S2. Figure 9 It can be seen that the drain-source voltage of the switch tube S2 drops to zero before it is turned on, which proves that the ZVS operation is realized.

[0051] Figure 10 is an efficiency test curve of the experimental prototype of the double-output DC-DC converter. Figure 10 It can be seen that due to the realization of ZVS, the efficiency of the experimental prototype is as high as 89% in the whole test range, and the highest efficiency can reach 91.8%.

[0052] By increasing the number of output branches, the double-output DC-DC converter can be expanded into an N-way multi-output converter. The working principle of the double-output DC-DC converter is specifically analyzed above, and the working principle of the N-way multi-output DC-DC converter is the same as that of the double-output DC-DC converter.

[0053] The above is only the preferred embodiment of the present application, and does not limit the present application, any simple modification, change and equivalent structure change according to the technical essence of the present application to the above embodiment are still within the protection scope of the technical solution of the present application.

Claims

1. A multi-path weakly coupled wide voltage output DC-DC converter based on zero voltage switching, characterized in that: The direct current input power supply V in and N output branches, N is a positive integer and N≥2; Input power supply V in The switch tube S1 is connected with the inductor L1 and the first output branch. The capacitor C1, the diode D and the capacitor C2 are connected in series and then connected in parallel between the source of the switch tube S1 and the ground. The inductor L2 is connected in parallel between the diode D and the capacitor C2. The load R1 is connected in parallel with the capacitor C2. The inductor L in the rest of the i output branch i+1 With the capacitor C i+1 And its parallel load R i In series and parallel after the switch tube S i Between the source and the ground, switch tube S i The source and the switch tube S i-1 Drain connected, S i Drain and input power V in Common ground, i∈[2,N].

2. The zero-voltage-switching-based multi-lateral weakly-coupled wide- voltage-output DC-DC converter of claim 1, wherein: There are N+1 working modes in each switching cycle, and there are N duty cycles D1, D2, …, DN+1 N The output voltage V o1 of each output branch can be adjusted by adjusting the size of the corresponding duty cycle o2 . oN ​ 3. The zero-voltage-switching-based multi-lateral weakly-coupled wide- voltage-output DC-DC converter of claim 1, wherein: The switch tubes S1, S2,..., S N STP75NF75 MOS tubes are used.

4. The zero-voltage-switching-based multi-lateral weakly-coupled wide- voltage-output DC-DC converter of claim 1, wherein: The switch tubes S1, S2, …, S N The switch tubes S1, S2, …, S

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