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The voltage regulation characteristic of autotransformer,external compensation of zero sequence current for three Y au .

论证自耦变压器的电压调整性能、三Y型自耦变压器的零序电流外补偿、自耦变压器继电保护整定的特殊问题。

In this paper the reason of rapid increase of single phase short circuit current in 500 kV substation is analyzed. Through the calculation it is proved that neutral grounding by small reactance is an effective measure to reduce the single phase short circuit current, and the calculation method of the zero\|sequence reactance after autotransformer neutral grounding by small reactance being applied is expounded.

文中研究了500kV变电站单相短路电流急剧增长的原因，计算了变压器中性点经小电抗接地对限制单相短路电流的作用，论证了经小电抗接地是限制单相短路电流的有效措施之一，并阐述了500kV自耦变压器中性点经小电抗接地后，其等值零序电抗的计算方法，可供工程参考。

The conclusion is most of developed country levying value-added tax, the consist way is give tax-free police to core financial operation, levying standard tax rate to auxiliary financial operation and levying zero tax to exit operation.

得出的结论是：目前大部分发达国家都对商业银行征收增值税，比较一致的做法是对银行从事的核心金融业务采取免税政策，附属金融业务按标准税率征税，对出口金融业务实行零税率。

If the average slip velocity is zero, there is no holdup of one phase relative to the other.

如果平均滑移速度为0，也就没有一相对另一相的滞留。

Put forward using axial symmetry model to calculate zero-sequence impedance of power transformer. The results comparing with the testing value are correct.

提出使用准三维轴对称物理模型计算变压器的零序阻抗，并用实际模型和实验数据验证了计算结果，其结果是合理的。

A sensorless BLDC motor system with novel rotor position detection method based on back electromotive force and zero crossing is presented.

通过仿真结果证明，实时的改变PID参数值能够提高电机控制的性能，适应高精度伺服系统的需求。

In addition, since the back electromotive force occurring in an inductance element is cleared to zero during a half wavelength of period of the cosine wave, speed electromotive force can be measured by immediate shifting from a setting period to a measuring period.

另外，由于在余弦波的周期的半波长期间，使在电感元件中产生的反电动势VL清零，通过立即从设置周期转移到测量周期，能测量速率电动势。

The simulation results show that the vector control system based on this improved scheme has better dynamic and static performance. It solves a lot of problems such as larger error in the MRAS based on the back electromotive force when the motor runs across the zero speed and the instability based on the instantaneous reactive power in the regenerating mode and has high estimating precision.

仿真表明基于该方法的矢量控制系统动静态性能好，能有效解决反电动势模型参考自适应方法在速度过零点辨识误差大以及瞬时无功功率模型参考自适应方法在转速给定为负阶跃时转速不稳定问题，转速估计精度高。

The key points of sensorless technology in PMBLDCM are to study a method which can detect rotor position accurately by simply method in whole speed range. After analyzing current sensorless methods of the PMBLDCM, it is found that those methods are successful at middle and high speed, but they often fail to detect rotor position at low speed when the back electromotive force is small or zero.

纵观目前的永磁无刷直流电机的无位置传感器控制方法，比较成熟而可行的方法多集中于电机在中高速区域运行时，能够较准确估计转子位置；电机处于低速、极低速、静止状态时电加热管，因为反电动势幅值较小或者为零，而无法正常工作。

Nintendo's 0.8 score is a marginal improvement on the dead-zero score they received back in 2007, but it keeps them squarely in last place.

任天堂的0.8分仅比他们07年得到的接近0分好了一点，这使他们排在最后的位置。

For the head-teacher of the class said that I had seriously broken the school rules,which led me to a three-day suspend class.

为什么呢？因为我的班主任说我严重的违反了校规，于是让我停课三天。

Many of them believe that the conversion of thousands of working-class folk in England spared that nation from the mass carnage and the tyranny that came with the revolution in France.

他们之中有许多人相信，在英国数以千计的劳工阶级之悔改信主使英国免於遭受如法国大革命所造成的大屠杀和专制暴政。