直流

Firstly, this paper analyzes and summarizes the research situation of resonant soft-switching technique and main topologies. And it indicates the main advantages and disadvantages. Then it pays more attention to analyze the parallel resonant DC link circuit theory and operating modes. It also analyzes how the resonant circuit realizes the resonant process. This paper also simplifies the control part design of the parallel resonant DC link soft-switching inverter by DSP.

本文首先对谐振软开关技术的研究现状和各种主要的拓扑结构进行了分析、综合、总结，指出了各自的优缺点；着重对并联谐振直流环电路的工作原理、电路工作模式、软开关实现机理及谐振参数的确定等进行了深入详尽的分析；利用DSP的灵活调节特点，有效地简化了并联谐振直流环软开关逆变系统的控制环节设计。

The DC reactive power is the only parameter to be specified in calculation, and the partial differential formulas in Jacobian matrix do not change when the DC control model changes.

计算时，只需规定换流器直流侧的无功功率，而且当直流系统控制方式发生变化后不需重新推导Jacobian矩阵中的偏导公式。

A different test voltage must be used as compared with AC (1.414xAC RMS Voltage=DC Peak voltage).

同样的测试，与交流电压相比较﹐直流测试电压数值是不同的(1.414 X 有效值电压=直流峰值电压)。

The electric power generated by pithead power plants in Mongolia will be transmitted to load center of North China power grid, i.e., Beijing―Tianjin―Tangshan area, through China-Mongolia HVDC project. The isolated island operation mode is used for the AC power system at the sending end of HVDC system.

蒙古煤电资源通过中蒙直流输电工程直接送往我国华北电网京津唐负荷中心地区，直流输电系统送端采用"孤岛"运行方式。

The AC power supply unit provides AC voltage for the signal generating unit and the high voltage amplifying unit.

直流电源单元为信号发生单元和高压放大单元提供直流电压。

For large capacity of inverter, due to the dc bus voltage is higher, ac output generally do not need to boost transformer can achieve 220V, in medium and small volume of inverter, due to the low voltage dc 12V, such as, must design, 24V pressor circuit.

对大容量的逆变器，由于直流母线电压较高，交流输出一般不需要变压器升压即能达到220V，在中、小容量的逆变器中，由于直流电压较低，如12V、24V，就必须设计升压电路。

This paper proposes a novel zero-voltage and zero-current-switching pwm three-level converter, which introduces a block capacitor in series with the primary winding of the transformer to make the primary current to reduce to zero during zero state.

提出一种新颖的零电压零电流开关PWM三电平直流变换器，它是在基本的三电平直流变换器的变压器一次侧串入一个阻断电容，使一次电流在零状态时减小到零。

The flux hysteresis controller was ignored in the constant torque region and an improved method was proposed to make the estimation of torque easier.The proper stator voltage space vector was selected based on the output of the torque hysteresis controller and the sector which the current rotor flux locates in.

摘 要：针对无刷直流电机直接转矩控制中磁链观测困难、控制复杂等问题，提出了一种应用于无刷直流电机二二导通方式下的新型直接转矩控制方法：在电机基频以下调速时，略去了常规的磁链观测控制环节，改进了转矩计算方法，通过转矩滞环控制选择所施加的空间电压矢量。

A new brushless DC motor DTC scheme was studied to solve those problems associated with direct torque controlof brushless DC motor,such as difficulty to control flux and complexity to estimate torque.The flux hysteresis controller was ignored in the constant torque region and an improved method was proposed to make the estimation of torque easier.The proper stator voltage space vector was selected based on the output of the torque hysteresis controller and the sector which the current rotor flux locates in.

摘 要：针对无刷直流电机直接转矩控制中磁链观测困难、控制复杂等问题，提出了一种应用于无刷直流电机二二导通方式下的新型直接转矩控制方法：在电机基频以下调速时，略去了常规的磁链观测控制环节，改进了转矩计算方法，通过转矩滞环控制选择所施加的空间电压矢量。

Research and Design of Push-Pull Forward and Soft-Switching Circuit

本文结合推挽正激直流变换器和高频脉冲直流环节逆变器的优点，提出了一种适用于低压大电流输入场合的逆变器，并对构成这种逆变器的电路拓扑、SPWM控制策略、稳态原理特性进行了深入的分析研究。

I'm strongly against the death penalty — it's an eye for an eye.

我不赞成死刑——这是以牙还牙的报复行为。

And to get you the support you need, we're enlisting all elements of our national power: our diplomacy and development, our economic might and our moral suasion, so that you and the rest of our military do not bear the burden of our security alone.

并给你们所须的支援，我们正徵召国家所有各种的力量：我们的外交及发展，我们的经济力量与道德劝说，所以你们与其他军人不须要孤独地负起国家安全的责任。