A high-speed vector-controlled spindle motor drive with closedtransition between with encoder control and without encoder control

A 40000-r/min vector-controlled induction motor drive is introduced. The vector control of induction motors has been widely accepted in spindle drives of machine tools where they replace conventional DC motors because of the low maintenance requirements. Another important feature of the AC spindle drive is its high-speed capability. The magnetic encoder is most widely used as the speed detector because it is suited for use in an adverse environment. However, the magnetic encoder with high resolution and a high S/N ratio loses the output pulses at extremely high speed. In the drive system introduced, the conventional vector control is used in the low-speed range, and the vector control without the encoder is used in the high-speed range. Close transition between two modes is made without interrupting the operation     

Digital field-oriented control for dual three-phase induction motor drives

A direct rotor-field-oriented control of a dual-three phase induction motor drive is described in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees. The stator windings are fed by a current-controlled pulsewidth-modulation (PWM) six-phase voltage-source inverter. Three key issues are discussed: (1) the machine dynamic model is based on the vector space decomposition theory; (2) the PWM strategy uses the double zero-sequence injection modulation technique which gives good results with low computational and hardware requirements; and (3) to eliminate the inherent asymmetries of the drive power section, a new current control scheme is proposed. Experimental results are presented for a 10-kW dual three-phase induction motor drive prototype.     

Double-fed induction generator control for variable speed wind power generation

Vector control of a doubly fed induction generator drive for variable speed wind power generation is described. A wound rotor induction machine with back-to-back three phase power converter bridges between its rotor and the grid forms the electrical system. The control scheme uses stator flux-oriented control for the rotor side converter bridge control and grid voltage vector control for the grid side converter bridge. A complete simulation model is developed for the control of the active and reactive powers of the doubly fed generator under variable speed operation. Several studies are performed to test its operation under different wind conditions. A laboratory test setup consisting of a wound rotor induction machine driven by a variable speed dc motor is used to validate the software simulations.     

PERFORMANCE ANALYSIS OF LOAD COMMUTATED INVERTER FED CAGE INDUCTION MOTOR DRIVE

ABSTRACT

An approach, to analyse the performance of a variable speed cage induction motor drive fed from load commutated inverter (LCI), is presented. Induction motor with an appropriate capacitor across its stator terminals constitutes the load on the inverter. A fully controlled bridge converter, supplied by a variable dc voltage source, commutated with the back emf of the motor, acts as an inverter. An algorithm to compute the motor performance, is developed using equivalent circuit representation of the system. Strategies for the selection of control variables, in order to achieve the desired speed range for satisfactory performance of the drive are given. The performance of a 3-hp, cage induction motor fed from LCI is computed, using the developed algorithm for wide range of speed; and is verfied experimentally.     

电动车用感应电机磁场定向矢量控制研究

电动车用感应电机参数变化易引起电机振荡现象，文中以含微分运算的三相感应电机模型为基础，提出了一种具有转差频率控制的转子磁场定向矢量控制方法，给出了相关的理论推导及实验结果。该方法能够有效地抑制由于电机参数变化过大导致的电机振荡现象，能使电机可靠地运行于弱磁区域，可满足高功率密度、高转速电动车用感应电机的控制要求。实验结果验证了该方法的正确性及有效性。     

High Response Control of Stator Watts and Vars for Large Wound Rotor Induction Motor Adjustable Speed Drives

Extremely rapid control response (0.01 s) of stator watts and vars has been obtained on a 15 000-hp wound rotor induction machine with a cycloconverter controlled secondary by means of an orthogonal control scheme which linearizes the machine equations and combines both feedforward and feedback error signals. Leading and lagging power factor and positive or negative stator power flow can be smoothly and rapidly controlled over a speed range in excess of ±35 percent of the induction motor synchronous speed. This doubly fed drive may be termed a "Scherbiustat drive" because the wound rotor induction motor secondary power conversion equipment is the static equivalent of the Scherbius machine. This type of a drive does not employ a dc link in the motor secondary power conversion equipment. It should not be confused with a static Kraemer drive which employs a dc link in the frequency conversion process and was so named because of its similarity to the original Kraemer drive which uses a synchronous converter and a dc motor in the secondary power conversion process. Recently obtained field results have verified the original study results discussed herein.     

高速无位置传感器无刷直流电动机控制系统

高速无刷直流电动机超过10 000 r/min,换相时间极短,对无位置传感器的控制系统的设计和实现提出了更高的要求。针对无位置传感器的高速无刷直流电动机控制进行研究,采用一种基于反电动势过零点检测换相技术的改进方法。在程序控制方面采用多中断嵌套、滤波算法来提高电机反电动势过零点检测的精度和抗干扰性能;在硬件设计方面将电机三相合成电压分压值与母线分压值进行比较来检测过零点。该设计电路简单,成本低,动态性能好。实验结果表明,该方案有效可行,能够保证电机在较高的额定转速下稳定运行。     

Design and Control Techniques for Extending High Frequency Operation of a CSI Induction Motor Drive

An investigation of the maximum speed capability of a current source inverter (CSI) drive in both a three-and a six-phase connection is presented. It is shown that a six-phase configuration has distinct advantages over a three-phase connection in high speed capability for the same peak motor spike voltages. In addition, with proper control of the firing pulses fed to the inverters supplying the six-phase machine, the speed range can be substantially extended beyond the maximum limit predicted using conventional control. Predicted analytical results are correlated with results obtained by a detailed hybrid computer simulation.     

变频调速异步电动机的电磁计算及设计探讨

本文主要为变频调速异步电动机的设计提供一条思路。首先 ,对特定逆变电源供电的三相 (变频调速 )异步电动机进行实验 ,取得可靠实验数据。然后 ,确定电磁计算方法 ,并编制出与实验结果相符合的电磁计算程序。在此基础上 ,调整电动机参数 ,进行合理设计     

炒菜机直流电机控制器设计与实现

针对滚筒式炒菜机的锅体、叶片和倾倒动作的快速响应和平稳运行,设计了一种以STM32F767IGT6为主控制器的多电机协同控制器。采用74HC244隔离电路和双BTN7960芯片电机驱动电路实现电机控制,增量式编码器和光电耦合器测速电路实现速度反馈,PID算法实现速度的整定。试验表明,设计的多电机协同控制器能够实现电机的快速响应,电机在0.04～0.06 s稳定到预设速度,锅体、锅铲、倾倒控制电机可以实现同步和独立工作模式,并且相互影响可以忽略,满足炒菜机的动作需求。     

Using corona inception voltage for motor evaluation

Failures of the interturn insulation system of induction motors fed by PWM variable speed controllers have plagued the industry since the introduction of fast-switching, IGBT-based drives. The majority of these failures are attributed to high voltage stresses imposed upon the motor by the drive. Here, the author describes how the corona inception voltage can be used for evaluating the state of variable speed induction motor drive insulation     

Performance Improvement of Current Source Inverter-Fed Induction Motor Drives

A high performance variable speed drive system using current source inverter fed induction motor is described. The principle of the drive control is based on the field-orientation method, where the stator current is used as the vector quantity. To improve the system response and to operate smoothly at low speed, a current pulsewidth modulation (PWM) control is provided by means of a feedback loop. This system operates stably and shows a high dynamic performance in a wide range, from zero to rated speed. Dual current source inverter is applied to this drive system which results in a remarkably low copper loss of the motor, even in PWM operation.     

A Cycloconverter?Synchronous Motor Drive for Traction Applications

An electric drive suitable for traction is described consisting of a cycloconverter and a synchronous motor. Essentially, the same system can be used with either single-phase or three-phase input with frequencies around 50-100 Hz. The motor speed range is not limited by the input frequency. The cycloconverter thyristors are commutated by the source voltage at low motor speed and by the motor electromotive force (EMF) at higher speed. The transition between the two regions is smooth and automatic. Only 16 low- switching speed thyristors are required for the single-phase input system. The short time overload capability of this drive at low speed is excellent, and full range regenerative, as well as dynamic braking, is readily accomplished. Compared to dc motors occupying the same space, three-phase ac motors, both synchronous and induction, offer higher output power, higher efficiency, and the elimination of brush and commutator maintenance. Compared to inverters, cycloconverters have higher efficiency and lower cost and weight.     

Dual three-phase induction motor drive with digital current control in the stationary reference frame

Among different multiphase motor drive solutions, one of the most widely discussed is the voltage source inverter (VSI) fed dual three-phase induction machine. Over the years, various topics pertinent to this specific motor drive system have been investigated in considerable depth and, more recently, various reports on real-world applications have emerged. In this paper, a drive system that has been developed specifically for electrical vehicles is described. For vector control purposes, the drive was modeled using an approach that is based on the vector space decomposition technique since it directly leads to the proposed current control method in the stationary reference frame.     

Extended high-speed operation via electronic winding-change method for AC motors

In many applications, it is often needed to extend the speed range of an electric motor. In permanent-magnet ac motors (PMAC), the maximum speed is limited by the available voltage for a given counter electromotive force value. The extension of the speed range can be achieved to some extent by using the field-weakening principle, resulting in constant-power characteristics, but is limited by machine parameters and inverter rating. In an induction-motor-based spindle drive for machine-tool applications, the wye/delta switchover method remains popular for extending the constant-power range without sacrificing the torque capability at higher speeds. Conventionally, the wye/delta method employs mechanical contactors that have limited life and are associated with dead time in the range of tens to hundreds of milliseconds due to mechanical constraints. Power-electronic versions of the contactors have been proposed, but they are rather complicated and involve many switching devices. This paper describes a novel and simple switching technique involving only two three-phase diode bridges and two insulated gate bipolar transistor (IGBT) switches to extend the speed range of ac machines (induction as well as permanent-magnet type). The proposed method requires a center tap to be placed in each phase of the motor with access to the ends and the center tap, making the motor a nine-lead machine. Test results carried out on a nonsalient-type PMAC motor and an induction motor are given to support the idea.     

Application of Direct-Drive Wheel Motor for Fuel Cell Electric and Hybrid Electric Vehicle Propulsion System

This paper presents a gearless wheel motor drive system specifically designed for fuel cell electric and hybrid electric vehicle propulsion application. The system includes a liquid-cooled axial flux permanent-magnet machine designed to meet the direct-drive requirements. The machine design implements techniques to increase the machine inductance in order to improve machine constant power range and high-speed efficiency. The implemented technique reduces machine spin loss to further improve efficiency. The machine design also optimizes the placement of magnets in the rotor to reduce cogging and ripple torque. An original cooling system arrangement based on the use of high thermal conductivity epoxy joining machine stator and liquid-cooled aluminum casing allows the very effective removal of machine power loss. Design details and experimental results are presented.     

低损耗电压频率比控制的变频调速系统性能仿真研究

本文从满足调速范围及最小铜、铁耗总和出发，推导了考虑主磁路饱和的电机数学模型，研究了电压频率比的控制规律，同时对系统脉动转矩进行了准确分析，并利用改进后的电压频率比控制规律，对实际电机进行了调速性能的仿真计算。结果表明，采用电压频率比不为常数的控制，拓宽了调速范围，提高了电机在调速过程中的效率，降低了轻载低速时的转速脉动，对变频器控制规律与电机的配合提供了理论基础。     

Microcomputer Control of Variable Frequency Drives Using the Submersible Motor as an Instrument

The production of a submersible pump can be optimized with the use of a microcomputer-controlled variable frequency drive. A new approach to monitoring the pump and motor performance is presented. Instead of downhole sensors, pressure bomb, or acoustical wave method, the three-phase induction motor is used as a sensing instrument to determine downhole pressure, both static and flowing. A new electronic device, installed at the surface, has been developed and tested to monitor the actual revolutions per minute (r/min) of the downhole pump and motor. Using the basic induction motor equivalent circuit, the motor terminal voltage can be determined and thus controlled to meet the motor manufacturer's design criteria. The detailed analysis then permits calculation of the liquid level which can be used as the governing parameter for oil production. Also a method is discussed to prevent cavitation, determine specific gravity, and calculate downhole temperature.     

晶闸管控制的单相–三相变换器

提出一种单相电源供电时适用于异步电机传动的单相–三相变换器。由于仅采用7个晶闸管和1个移相电容,该变换装置具有造价低、结构简单的特点。分析该变换器的工作原理及开关过程,并提出一种基于开环变压变频(variable voltage variable frequency,VVVF)和变压恒频(variable voltage constant frequency,VVCF)控制的单相–三相离散跳频控制策略,用于电机的起动和稳态运行控制,一方面保证了电机在低频阶段足够大的起动力矩,另一方面可使电机稳步起动到额定转速。仿真和实验结果表明了该控制策略的有效性以及系统方案的可行性。     

Rotor resistance adaptation for sensorless vector-controlled induction machines

The vector control method is widely used for induction motor drives. In these applications, a rotational transducer such as a shaft encoder is used. A rotational transducer, however, cannot be mounted in some cases, such as motor drives in a hostile environment or high-speed motor drives. Several sensorless vector-controlled induction machine drive methods have been proposed. These methods have the disadvantage that rotor resistance variation causes errors in the estimation of the motor speed. It is difficult to estimate the motor speed and the rotor resistance simultaneously, because the equivalent rotor resistance is the ratio of the rotor resistance to the slip at steady state. Therefore, we have proposed a method of simultaneously estimating the motor speed and the rotor resistance of an induction motor by superimposing ac components on the field current command. This paper presents a modified method of the rotor resistance adaptation. The validity of the proposed method is verified by experiments. © 1998 Scripta Technica, Electr Eng Jpn, 125(2): 65–72, 1998