﻿ 一种应用于直流配电网的隔离直流变换器软启动方法
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 山东大学学报(工学版)  2017, Vol. 47 Issue (4): 37-42  DOI: 10.6040/j.issn.1672-3961.0.2017.101 0

引用本文

PAN Yiwei, YUAN Shuai, CHEN Alian, ZHANG Chenghui. A soft starting method for the isolated DC/DC converter in DC distribution systems[J]. Journal of Shandong University (Engineering Science), 2017, 47(4): 37-42. DOI: 10.6040/j.issn.1672-3961.0.2017.101.

文章历史

A soft starting method for the isolated DC/DC converter in DC distribution systems
PAN Yiwei, YUAN Shuai, CHEN Alian, ZHANG Chenghui
School of Control Science and Engineering, Shandong University, Jinan 250061, Shandong, China
Abstract: To solve over current problem of the isolated DC/DC converter that commonly applied in DC distribution systems, a novel simple soft starting method was proposed. During the starting time, the dutycycle of the input side square wave voltage gradually changed from 0 to 0.5, while the DC voltage ramped from 0 to the final set value at the same time by phase shift control. By applying these two methods, current overshooting and capacitor voltage oscillation could be effectively suppressed. The system had a strong anti-disturbance capacity and do not require complex mode switching procedure as conventional soft starting method. Simulation results were provided to validate the effectiveness of the proposed soft starting method.
Key words: DC distribution system    DC/DC converter    phase shift control    soft start
0 引言

1 隔离型双向全桥变换器工作原理

 图 1 双有源桥拓扑 Figure 1 Topology of the dual active bridge converter
 图 2 双有源桥等效模型 Figure 2 DAB Equivalent model

 ${{\dot U}_{{\rm{pri}}}} = {U_{{\rm{pri}}}}\angle 0,\dot U{_{{\rm{sec}}}} = {U_{{\rm{sec}}}}\angle \varphi ,$ (1)
 ${{\dot I}_{L{\rm{s}}}} = \frac{{{U_{{\rm{pri}}}}\angle 0 - {U_{{\rm{sec}}}}\angle \varphi }}{{{\rm{j}}\omega {L_{\rm{s}}}}},$ (2)

 $P = {\rm{Re}}({{\dot U}_{{\rm{sec}}}} \cdot I_{Ls}^*) = \frac{{{U_{{\rm{pri}}}}{U_{{\rm{sec}}}}{\rm{sin}}\varphi }}{{\omega {L_{\rm{s}}}}}。$ (3)

2 提出的软启动方法

 ${U_{{\rm{pri}}}} = \frac{{4{U_{{\rm{dc}}1}}}}{{\rm{ \mathsf{ π} }}}{\rm{sin}}\left( {\frac{\theta }{2}} \right){\rm{sin}}\left( {\omega t} \right)。$ (4)

 ${i_{{L_{\rm{s}}}}}\left( t \right) = \frac{{{U_{{\rm{in}}}}}}{R}\left( {1 - {e^{\frac{{ - {R_{{L_{\rm{s}}}}}}}{{{L_{\rm{s}}}}}t}}} \right),{\rm{ }}t \in \left[ {\begin{array}{*{20}{c}} {0,}&{\frac{{{T_{\rm{s}}}}}{2}} \end{array}} \right],$ (5)

 ${i_{{L_{\rm{s}}}}}\left( t \right) = {U_{{\rm{in}}}}t/{L_{\rm{s}}}。$ (6)

2.1 输出侧开关闭锁启动策略与改进方法

 图 3 输出侧开关闭锁启动方法电压波形示意图 Figure 3 Voltage waveform diagram of starting method with output bridge off

 ${\varphi _1} = \frac{1}{2}({\rm{ \mathsf{ π} }} - d{\rm{ \mathsf{ π} }})。$ (7)
 图 4 t1时刻前方波电压与电感电流波形 Figure 4 Square voltage and inductor current waveforms before t1

 图 5 改进的输出侧开关闭锁启动方法流程图 Figure 5 Flow diagram of the improved soft starting method that output bridge is off
2.2 占空比和移相控制协同调节方法

 ${{\dot I}_{{L_{\rm{s}}}}} = \frac{{{U_{{\rm{pri}}}} - {U_{{\rm{sec}}}}{\rm{cos}}\varphi - j{U_{{\rm{sec}}}}{\rm{sin}}\varphi }}{{j\omega {L_{\rm{s}}}}}。$ (8)

 $I_{{L_{\rm{s}}}}^2 = \frac{{{{({U_{{\rm{pri}}}} - {U_{{\rm{sec}}}})}^2} + 2{U_{{\rm{pri}}}}{U_{{\rm{sec}}}}(1 - {\rm{cos}}\varphi )}}{{{\omega ^2}L_{\rm{s}}^2}}。$ (9)

 $I_{{L_{\rm{s}}}}^2{|_{\varphi = 0}} = {({U_{{\rm{pri}}}} - {U_{{\rm{sec}}}})^2}/({\omega ^2}L_{\rm{s}}^2)。$ (10)

 $\Delta {i_{{L_{\rm{s}}}}} = \frac{1}{{{L_{\rm{s}}}}}\int_0^{{T_{\rm{s}}}/2} {\left( {{U_{ab}}\left( t \right) - {U_{cd}}\left( t \right)} \right){\rm{d}}t} 。$ (11)

 图 6 输入输出侧H桥方波电压伏秒平衡示意图 Figure 6 Volt-second balance diagram of input and output side square voltage waveforms
 $\int_0^{{T_{\rm{s}}}/2} {{U_{ab}}{\rm{d}}t} = \int_0^{{T_{\rm{s}}}/2} {{U_{cd}}{\rm{d}}t} 即\int_0^{d'{T_{\rm{s}}}} {{U_{{\rm{in}}}}{\rm{d}}t} = \int_0^{{T_{\rm{s}}}} {{U_{{\rm{out}}}}{\rm{d}}t} ,$ (12)

dUin=Uout=dUin, d=d′, 可保证启动过程中UpriUsec。通过闭环控制追踪斜坡给定电压dUdc*, 使输出电容电压平稳上升, 并在充电过程中使φ不致饱和。故本研究提出的软启动方法为:在设定的软启动时间tstart内, 输入侧H桥输出方波电压占空比d′逐渐由0增加到0.5, 同时输出侧电压给定设定为dUdc*, 输出侧H桥输出方波电压占空比始终保持0.5。占空比和移相控制同时调节, 占空比和电压给定值按照相同的斜坡函数变化。控制框图如图 7所示。

 图 7 占空比与移相控制协同调节软启动方法控制框图 Figure 7 Control digram of soft starting method that ducycycle control and phase shift control are coordinitely regulated
3 验证结果

 图 8 方法一启动电压电流波形 Figure 8 Voltage and current waveforms of starting method Ⅰ

 图 9 方法二启动电压电流波形 Figure 9 Voltage and current waveforms of starting method Ⅱ

 图 10 改进的方法二启动电压电流波形 Figure 10 Voltage and current waveforms of the improved starting method Ⅱ

 图 11 本研究提出的方法启动电压电流波形 Figure 11 Voltage and current waveforms of starting method proposed in this paper

 图 12 稳态负载突变时电压电流波形 Figure 12 Voltage and current waveforms when load transients during steady state

4 结论

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