直流的

On the base of roundly analyzing and studying phase relation of stator magnetometive force and rotor one of brushless DC motor,the main purpose of this paper is to analyze thoroughly positive and negative rotation logic layout of sensorless BLDCM,and explains the differences between BLDCM and sensorless BLDCM.

依据无刷直流电动机定转子磁势的相位关系，深入分析无位置传感器无刷直流电动机正反转控制的逻辑编排，并分析了无位置传感器和有位置传感器正、反转控制的不同。

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。

Some error sources of evaluation are discussed, including the errors of signal source, the measurement errors of the calibrated system, the influence of quantization error of calibrated system, the environment influence, and so on.

讨论了影响评价结果不确定度的几个主要误差来源，包括信号源误差、被校系统测量误差、被校系统量化误差的影响等等，给出了端基直流增益和直流偏移测量结果的不确定度。

The keystone of this device as follows : input three phase AC power supply of 380V±15%, become DC after primary full-bridge commutation wave filter, convert high frequency AC pulse of over 20KHZ using IGBT inverter module, become DC power supply for the usage of producing ozone after step-up of High Frequency Transformer and commutation of quickness rectifier tube and reactor.

高频高压臭氧发生装置的基本原理是：输入380V±15%三相交流电源，经初级全桥整流滤波成为直流，通过IGBT逆变部件，转换成20KHZ以上的高频交流脉冲，再经高频变压器升压，最后由快速整流管、电抗器整定为可供发生臭氧用的直流电源。

Direct current with the positive pole earthed and the negative pole connected to the test electrode by means of a low capacitance unscreened lead.

b直流电源的正极接地，负极由一根低电容的非遮罩电线与试验电极连接。电源输出电压应为脉动因数不大於5%的直流电压。

B Direct current with the positive pole earthed and the negative pole connected to the test electrode by means of a low capacitance unscreened lead.

b直流电源的正极接地，负极由一根低电容的非屏蔽电线与试验电极连接。电源输出电压应为脉动因数不大于5%的直流电压。

A DC-to-DC converter includes a pulse width modulation circuit cooperating with at least one power switch for supplying power from a source to a load over a range between a lower limit and an upper limit to thereby control an output voltage for the load.

一种直流-直流转换器，包括一个与至少一个的电源开关协作，以在一个上限和下限的范围内由电源向负载供电，从而为负载控制输出电压的脉宽调制电路。

The possibility for preparing nanocrystalline materials by jet-electrodeposition technique is also analyzed. Corresponding the research in the article, a set of unsubmerged single circular jets equipment was designed. In chapter 2, jet-electrodeposition was carried out both under direct current condition and pulse current condition. A series of samples for nanocrystalline nickel coating were prepared under different deposition parameters.

在第二章中，采用喷射电沉积技术分别使用直流和脉冲两种波形的电流进行电沉积，改变电沉积工艺参数制备了一系列的纳米晶镍镀层样品，使用X射线衍射、扫描电镜、透射电镜、维氏硬度计等仪器对镀层微观结构和性能进行了分析和表征，主要考察了在直流喷射电沉积和脉冲喷射电沉积方式下，沉积参数如电流密度、电镀液喷射速度等对镀层微观结构和显微硬度的影响。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。