Because of many attractive characteristics , such as low switch voltage stress , inherent anti - break - through capability , high reliability , two - transistor forward converter ( ttfc ) has become one of the most widely used topology 双管正激变换器具有开关电压应力低、内在抗桥臂直通能力和可靠性高等优点，已成为目前比较广泛应用的拓扑之一。
The four leg inverter with a neutral leg can control the zero sequence voltages and currents , suitable for the unbalanced loads , widely used in applications require a precise neutral current control , such as ups , aviation power , et al 四桥臂逆变器由于采用第四个桥臂作为四线制输出的中点,所以可以控制零序电压和电流,适用于ups ,航空电源等带不对称负载的场合。
According to the research of the converter s transient operation , the thesis presents the design of the resonant parameters and the dead - time setting range of the converters lead leg and lag leg , and i is confirmed by simulation 论文在对变换器暂态工作过程研究的基础上，给出了软开关谐振参数设计和变换器超前桥臂、滞后桥臂的死区时间设置范围，仿真验证了设计的有效。
Compared with full - bridge or half - bridge converter , a two - transistor forward converter has no risk of direct break - through in the two transistors of the same leg , it is suitable for high voltage input high power output application 另外,和全桥变换器或是半桥变换器相比,交错并联双管正激变换器不存在桥臂直通的缺陷,因而比较可靠。因此,它适合于高压输入大功率输出的应用场合。
Based on the research on one - cycle control theory , one - cycle control is applied to three - phase four - wire apf with four - leg in this paper . analysis for the average model of the apf in switching period is performed and the control equation is derived 本文在研究单周控制理论的基础上，将单周控制用于四桥臂三相四线制有源电力滤波器，通过分析其开关周期平均模型，推导出它的控制方程。
The main works and conclusions in this paper are as follows : for compensating unbalanced power system , through comparing accustomed structures of main circuit , the main circuit of asvg advanced in this paper is selected for the first time as a converter with four legs 本文的主要工作和结论如下：通过对现有asvg主电路结构的对比分析，针对不平衡电力系统的补偿要求，提出以四桥臂变流器作为asvg的主电路。
The voltage of bridge capacitor will become unbalanced , when inverter ' s input side is a single source . this phenomenon is inherent with the control of voltage feedback . a balance winding can overcome this shortcoming and widen the application of this circuit 采用单电源供电的半桥电路，如仅采用电压反馈控制方案无法克服桥臂电容电压的不平衡，通过加入平衡绕组可以克服这一缺陷，扩大电路的应用场合。
The dynamic model of asvg is established , which is regard as bases of transforming the reference currents to the reference voltage . principle of selecting main model parameters is discussed . based on the ip - iq method , the reference current signals are detected from load currents 本文建立了四桥臂asvg的动态模型，以此作为参考电流转化为参考电压的依据；讨论了模型主要参数的选取原则；确定了以ip - iq法作为参考电流的检测方法。
In the design of real - time control system , the paper takes three - phase full - bridge mosfet inverter as the real - time control main circuit , and adopts a control scheme with 120 ? switching mode combined with half - bridge pulse width modulation ( pwm ) , which would avoid straightthrough short of a certain bridge . phase current is detected by single current sensor ; three - phase position signals generated by position sensors could not only supply commutation information for inverter , but also be used for speed detecting based on signals " period measurement , which makes the speed sensor unnecessary . the whole control system adopts speed and current dual closed - loop control strategy in order to construct a high performance rare - earth permanent magnetic brushless dc motor ( repm bldcm ) full - digital real - time control system 在实时控制系统的设计中，本文以三相全桥mosfet逆变电路作为实时控制主电路，采用120导通方式结合半桥pwm调制的控制方案，从而有效地避免了桥臂的直通短路；本文用单电流传感器实现对相电流的检测，来自位置传感器的三相位置信号不仅为逆变电路提供换相信息，而且也用于基于信号周期测量的转速检测，这样就省去了速度传感器；系统采用的是速度、电流双闭环控制策略，力求构建高性能的稀土永磁无刷直流电动机全数字实时控制系统。
By compared with the simulation results and the experiment results , we come to the conclusions that : ( 1 ) circuit with assistant network can widen soft - switching extent in lagging arm , reduces duty - cycle loss on the secondary , diminishes switching dissipation of inverter spot - welding power source . ( 2 ) the range of resonant capacitor , the important factor to soft - switching process , not only affects zero - voltage turn - off of power switches , but also affects the range of zero - voltage turn - on of power switches . so resonant capacitors must be considered according to many aspects ; ( 3 ) it easily fulfils soft - switching condition in lagging arm as leakage inductance of power transformer increases , but bigger leakage inductance of power transformer increases opening dissipation of transformer and decreases efficiency of soft - switching inverter power source 通过仿真结果与软开关点焊逆变器试验结果的对比分析，得到了如下主要结论：采用辅助网络可以完全拓宽全桥软开关逆变器的滞后桥臂软开关范围，减小了次级占空比丢失，降低了逆变电阻点焊电源的开关损耗；谐振电容是影响软开关工作状态的重要因素，其大小不仅影响开关管的零电压关断，同时也影响开关管的零电压开通范围，因此，谐振电容应该综合考虑；功率变压器漏感越大，越容易满足滞后桥臂的软开关条件，但是大的漏感也使变压器的通态损耗增加，降低了软开关逆变器的效率。
