A current sensorless drive system of a synchronous motor with a low‐resolution position sensor

High‐performance drive of synchronous motors such as a permanent magnet synchronous motor and a synchronous reluctance motor can be achieved by current vector control. In such drive systems, the armature current is controlled as a sinusoidal waveform based on rotor position information from a high‐resolution position sensor, and the current vector (d‐ and q‐axis currents) is suitably controlled by current feedback control. This paper proposes a current sensorless drive system with a low‐resolution position sensor in order to simplify the SM drive system. High‐performance current control is achieved in the proposed drive system, where the current sensors are eliminated and the simulated currents are used for current control. The low‐resolution position sensor is used instead of a conventional high‐resolution position sensor, and the higher position information is estimated. The steady‐state and transient characteristics are examined in several experiments with respect to the synchronous reluctance motor and the interior permanent magnet synchronous motor. It is confirmed that sinusoidal current drive, high‐performance current vector control, and speed control can be achieved by the proposed drive system. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(4): 34–43, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10072     

A new position‐sensorless position control method for high‐speed spindle systems

This paper proposes a new position‐sensorless position control method for high‐speed spindle drive systems. Mechanical vulnerability of position sensors such as an encoder mounted on a spindle motor is becoming a serious problem as required speed increases. For high speeds above 1500 rad/s, sensorless drive is preferred. It is possible for current technologies to control spindle motor in speed control mode without the sensor, but not in position control mode without the sensor. In the example of high‐speed spindle systems of automatic machine tools, implements must be automatically attached to and removed from the spindle at standstill. Automation necessitates position control, for which current technologies require a sensor. The proposed method makes it possible to realize pure sensorless high‐speed spindle systems performing in both speed and a position control modes. The method can attain a position control performance with quick settling from speed control and a repetitive positioning precision of 0.006 rad, 0.4°, which is comparable to that achieved by current sensor‐based methods. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(3): 58–69, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10059     

Experimental investigation of a speed‐sensor‐less IM drive system under Inverter fault‐tolerant control

This paper proposes an algorithm for fault tolerance of three‐phase, inverter‐fed, speed‐sensor‐less control of a three‐phase induction motor drive system. The fault tolerance of the inverter when one switch is open or one leg of six‐switch inverter is lost is considered. The control of the drive system is based on indirect rotor field‐oriented control theory. Also, the speed estimator is based on model reference adaptive system (using stator current and rotor flux as state variables for estimating the speed). The fault‐tolerant algorithm is able to adaptively change over from a six‐switch inverter to a four‐switch inverter topology when a fault occurs; also, it makes a smooth transition of the motor speed, torque, and current when changing over from a faulty condition to a new healthy status, which is four‐switch three‐phase inverter (FSTPI) topology; thus, the six‐switch three‐phase inverter (SSTPI) topology (pre‐fault status) is almost retained for the medium‐power range of induction motor applications. The proposed algorithm is simulated by using the MATLAB/SIMULINK package. Also, the proposed control system is tested experimentally using a digital signal processor (DSP1104). The obtained results from the simulation model and experimental system demonstrate the performance enhancement and good validity of the fault‐tolerance control for the speed‐sensor‐less induction motor drive system. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A novel quasi‐Z‐source indirect matrix converter

A new type of three‐phase quasi‐Z‐source indirect matrix converter (QZS‐IMC) is proposed in this paper. It uses a unique impedance network for achieving voltage‐boost capability and making the input current in continuous conduction mode (CCM) to eliminate the input filter. The complete modulation strategy is proposed to operate the QZS‐IMC. Meanwhile, a closed‐loop DC‐link peak voltage control strategy is proposed, and the DC‐link peak voltage is estimated by measuring both the input and capacitor voltages. With this proposed technique, a high‐performance output voltage control can be achieved with an excellent transient performance even if there are input voltage and load current variations. The controller is designed by using the small‐signal model. Vector control scheme of the induction motor is combined with the QZS‐IMC to achieve the motor drive. A QZS‐IMC prototype is built in laboratory, and experimental results verify the operating principle and theoretical analysis of the proposed converter. The simulation tests of QZS‐IMC based inductor motor drive are carried out to validate the proposed converter's application in motor drive. Copyright © 2013 John Wiley & Sons, Ltd.     

Usefulness of a frequency‐hybrid vector control for a sensorless induction motor drive

This paper examines and demonstrates the usefulness of a frequency‐hybrid vector control scheme for sensorless induction motor drive through actual‐machine‐based performance evaluation tests. The new approach utilizes a new indirect orientation scheme and a stable‐filter‐embedded direct orientation scheme, and exploits their advantages. It is confirmed through extensive tests with small and large standard motors such as 0.3, 3.7, 30 kW and special low‐voltage motors dedicated to electric vehicles that the sensorless vector control scheme has the following potential usefulness: (1) it can make machines that produce more than 200% rated torque at standstill, (2) in both motoring and regenerating modes, the rated torque can be produced even in the very slow speed range, including zero speed and zero frequency, (3) for constant speed, good linearity of torque response is attained, (4) it has the ability to track variable speed acceleration commands up to ±5000 rad/s² in the mechanical frequency sense, (5) it can accept a zero‐speed command and settles the machines to a stable standstill with no vibration, (6) it accepts instant injection of rated load even for zero‐speed control, and (7) it accommodates a load with huge inertia. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(4): 44–58, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10073     

A new generalized high‐frequency voltage injection method and mirror‐phase estimation method for sensorless drive of salient‐pole PMSMSs

This paper proposes a new generalized high‐frequency voltage injection method for sensorless drive of salient‐pole permanent‐magnet synchronous motors. The injected high‐frequency voltage has a unique spatially‐rotating elliptical shape, with the amplitudes of both the major and minor axes varying with the motor speed, and can be designed by selecting a design parameter. The high‐frequency current caused by the injected voltage, which has information on the rotor phase to be estimated, is speed‐independent, that is, is not affected by the motor speed at all. Consequently, the rotor phase can be estimated in a wide speed range from zero to the rated speed. By selection of the design parameter, the properties of the high‐frequency current can be adjusted appropriately to the associated motor‐drive system consisting of a motor and an inverter. As a versatile phase estimation method for estimating rotor phase using the high‐frequency current, the “mirror‐phase estimation method” is reconstructed and reproposed. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(3): 67–82, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20803     

A three‐phase hybrid stepping motor drive system combined with position‐sensorless closed‐loop control

This paper proposes a drive system for a three‐phase hybrid stepping motor, combining sensorless closed‐loop control with conventional open‐loop control. It is characterized by sophisticated control providing both prevention of pulling out from synchronism and suppression of natural rotor oscillation, without any position sensor attached to the motor shaft. A switching technique in chopper control which can enlarge the speed range controllable in the sensorless closed‐loop control is described. Starting and stopping sequences are developed to reduce mechanical natural oscillation produced in the transient state. Finally, the proposed drive system is compared experimentally with a conventional constant‐current open‐loop drive system. It is shown that the proposed drive system can perform the switchover from starting to sensorless closed‐loop operation within 20 ms, and can reduce the natural oscillation caused just after positioning. © 2000 Scripta Technica, Electr Eng Jpn, 131(3): 80–90, 2000     

Trends of permanent‐magnet synchronous machine drives

This paper presents recent trends of permanent‐magnet synchronous motor (PMSM) drive technologies in Japan. Since the PMSM drives have many advantages over other drives, e.g. high efficiency, high power density, etc., many of the motor applications have been changing their power sources to the PMSMs. Particularly, interior permanent‐magnet synchronous motors (IPMSM) are epoch‐making and are intensively studied among researchers, scientists and engineers. According to the survey of the recent innovative technical trends, the PMSM drive technologies have been making a remarkable advancement in the fields of analysis‐and‐design techniques, various sensorless‐control techniques, power converter control techniques, and application specific drive systems. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Potentiality of a new minimum‐order back‐EMF state observer taking acceleration into account for sensorless vector control of permanent‐magnet synchronous motors

This paper proposes new sensorless vector control methods for permanent‐magnet synchronous motors (PMSMs), which are based on a new minimum‐order back‐EMF state observer taking acceleration into account, and examines potentiality of the improved back‐EMF observer through experiments. Conventional sensorless vector control methods for PMSMs using an estimate of back‐EMF are established under the assumption of constant speed or zero acceleration, and consequently cannot operate properly at modes requiring rapid speed change especially in low speed region. On the other hand, the proposed back‐EMF observer has the following features: (1) it is a new back‐EMF state observer taking acceleration into account and requiring no additional approximation to motor mathematical model; (2) it is a minimum‐order state observer; (3) it utilizes motor parameters in the simplest manner; (4) it can be applied to both salient‐pole and non‐salient‐pole PMSMs; (5) it can be realized in both rotor and stator reference frames. Detailed designs and analyses for the improved state observer and the sensorless vector control systems in both rotor and stator reference frames are given. In relation to the sensorless vector control systems, this paper newly proposes a double‐integral‐type PLL method and an integral‐feedback‐type acceleration/speed estimation method. Their potentialities are examined through experiments. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(4): 78–92, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/ eej.20630     

Walsh function‐based position sensorless control for interior permanent magnet motor drives using ripple‐current of high‐frequency triangular‐wave‐carrier PWM inverter

This paper proposes the Walsh function‐based position sensorless drive method of a PM motor by using high‐frequency 20‐kHz triangular‐wave‐carrier PWM inverter ripple current. The proposed method uses the Walsh harmonic of PWM inverter ripple current to estimate the motor rotor position. By using the high‐frequency switching ripple current, the period of the rotor position estimation has been decreased and improves the step response of PM motor. The Walsh function makes it possible to use a definite integrator as the Walsh harmonic detector that can separate the small ripple‐current signal from the motor drive‐current signal. The Walsh harmonic detector circuit consists of less parts than the Fourier harmonic detector circuit. The validity of the proposed method was clarified by several experimental results. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(3): 80–88, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10205     

A new high‐frequency voltage injection method for sensorless drive of permanent‐magnet synchronous motors with pole saliency

This paper proposes a new sensorless vector control method for salient‐pole permanent‐magnet synchronous motors. In regard to rotor phase estimation, the sensorless vector control method is characterized by a new high‐frequency voltage injection method distinguished from the conventional ones by a unique ellipse shape of the spatial rotation, and by a new PLL method whose input is a high‐frequency current autocorrelated signal. The new vector control method established by two innovative technologies can have the following high‐performance and attractive features: (1) it can allow 250% rated torque at standstill; (2) it can operate from zero to the rated speed under the rated motoring or regenerating load; (3) it accepts instant injection of the rated load even for zero‐speed control; (4) it accommodates a load with huge moment of inertia; (5) phase estimation is very robust against inverter dead time; (6) the computational load for estimating rotor phase is very small, would be the smallest among the methods with comparable performance. This paper presents the new vector control method by focusing on two innovative technologies from its principles to design rules. Usefulness of the new vector control method is verified through extensive experiments. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(4): 62–77, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20632     

A sensorless drive system for brushless DC motors using a digital phase‐locked loop

This paper proposes a sensorless drive system for Brushless DC (BLDC) motors using a Digital Phase‐Locked Loop (DPLL). The Back Electromotive Force (BEMF) voltage is measured from the motor winding to determine the permanent magnet rotor position using the DPLL, and Pulse Width Modulation (PWM) limits the motor current to control the speed of BLDC motors. The proposed method can drive BLDC motors using an open‐loop control without stepping out. Also, the proposed method is compared experimentally with a control method that uses Hall sensors. Experimental results for the BLDC motor show the effectiveness of the proposed method. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(1): 57–66, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10074     

A new current control method for energy‐efficient/wide‐speed‐range drive of permanent magnet synchronous motor

This paper proposes a new current control method for energy‐efficient and/or wide‐speed‐range drive of salient‐pole permanent magnet synchronous motors. The proposed method is distinguished from conventional ones by the following features. (1) The original command is a signed current norm. (2) The exact d‐axis and q‐axis current commands that perform energy‐efficient and/or wide‐speed‐range drive are analytically and simply determined from the singed current norm command. (3) For speed control mode, the system turns out to be nonlinear, but its stability can be guaranteed based on Popov's stability theorem. (4) It can be applied for a mode similar to torque control. (5) Current limitation can be carried out accurately but very simply. Concrete analytical d‐axis and q‐axis current commands are presented, which satisfy exactly one of three optimum current control codes such as maximum torque, maximum power factor, and voltage limitation. A design method for PI speed controller that guarantees system stability is also presented. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(3): 66–77, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20305     

Energy‐Saving Technologies for Inverter Air Conditioners

Almost all residential air conditioners in Japan are inverter air conditioners in which a permanent magnet synchronous motor (PMSM) is driven by a PWM inverter. The inverter technology can reduce the energy consumption to less than half that of air conditioners driven by a constant‐speed induction motor (IM). This paper reviews the trends and the latest energy‐efficient technologies for the motor and the power converter that achieve considerable energy saving. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Principle and basic characteristics of a hybrid variable‐magnetic‐force motor

Reducing the power consumed by motors is important for energy conservation in the case of electrical appliances and electric vehicles (EVs). The motors used for operating these devices operate at variable speeds. Further, the motors operate with a small load in the stationary mode and a large load in the starting mode. A permanent magnet motor can be operated at rated power with high efficiency. However, the efficiency is low under a small load or at high speeds because the large constant magnetic force results in substantial core loss. Furthermore, the flux‐weakening current that decreases the voltage at high speeds leads to significant copper loss and core loss. Therefore, we have developed a new technique for controlling the magnetic force of a permanent magnet on the basis of the load or speed of the motor. In this paper we propose a novel motor that can vary the magnetic flux of a permanent magnet and clarify the principles and basic characteristics of the motor. The new motor has a permanent magnet that is magnetized by the magnetizing coil of the stator. The results of analysis show that the magnetic flux linkage of the motor can be changed from 37% to 100% and that a high torque can be produced. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(2): 47–57, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22309     

Wide range drive of hybrid stepping motor with flux‐weakening control

Because the application range of motors for position control is extending in industry, hybrid stepping motors that can realize position control easily have become popular. However, stepping motors have some disadvantages: the possibility of pull‐out under certain load conditions, and low efficiency due to iron loss. Consequently, a system designer must choose the motor‐driver combination very carefully. This paper proposes high‐efficiency drive of a hybrid stepping motor in a wide speed range by vector control, without the occurrence of pull‐out. It is shown that lead angle control is equivalent to flux‐weakening control, and that the maximum torque depends on the maximum inverter voltage at high speed. The effect of iron loss suppression by flux‐weakening control is verified experimentally. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(4): 68–74, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21022     

Characteristics evaluation of a CO2‐capturing power generation system with reheat cycle utilizing regenerative oxygen‐combustion steam‐superheater

A new CO₂‐capturing power generation system is proposed that can be easily realized by applying conventional technologies. In the proposed system, the temperature of medium‐pressure steam in a thermal power plant is raised by utilizing an oxygen‐combusting regenerative steam‐superheater. The CO₂ generated by combusting the fuel in the superheater can be easily separated and captured from the exhaust gas at the condenser outlet, and is liquefied. The superheated steam is used to drive a steam turbine power generation system. Using a high‐efficiency combined cycle power generation system as an example, it is shown that the proposed system can increase the power output by 10.8%, and decrease the CO₂ emissions of the entire integrated system by 18.6% with a power generation efficiency drop of 2.36% compared with the original power plant without CO₂ capture, when the superheated steam temperature is 750 ^°C. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(1): 35–41, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20575     

New sensorless vector control methods based on a new minimum‐order flux state observer in the “D‐module” for permanent magnet synchronous motors

This paper proposes new sensorless vector control methods that can be applied to both salient‐pole and non‐salient‐pole permanent magnet synchronous motors (PMSM). The proposed method estimates the phase of rotor flux by the “D‐module observer,” which is newly developed for sensorless vector controls of PMSM. The “D‐module observer” has the following attractive features. (1) It is a new state observer requiring no additional approximation to the motor mathematical model. (2) It is a minimum‐order state observer. (3) Observer gain guaranteeing proper estimation in a wide operating range except for singular zero‐speed can be a simple constant, and can be easily designed. (4) It utilizes motor parameters in the simplest manner. (5) Its structure is very simple and is realized at the minimum computing cost. (6) It can be applied to both salient‐pole and non‐salient‐pole PMSM. (7) It can be realized in both rotor and stator reference frames. Detailed designs and analyses for the “D‐module observer” and “D‐module observer”‐based sensorless vector control systems in both rotor and stator reference frames are given. Their validity and usefulness are examined and confirmed through extensive experiments. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(2): 46–62, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20046     

Development of Y‐branch joint for 275‐kV XLPE and fluid‐filled cable

When a new UHV substation is built in an urban region, generally, an existing underground transmission line will be diverted and drawn into the new substation. Compared with the latter construction method, enormous cost reduction of switching facilities and cable construction is expected when applying a Y‐branch joint (YJ) which is able to serve as a three‐way joint. The YJ has already been applied for 154‐kV‐class circuit, but it has not been investigated for 275‐kV‐class circuit. Since both XLPE and oil‐filled cable are presently used in 275‐kV‐class underground cable line, a universal design YJ for both cables has been investigated. The YJ was applied in a compact design which was based on our sophisticated electrical stress control technology for 500‐kV prefabricated‐type joint. Furthermore, the design was based on its prefabricated assembling technology. The YJ was verified as to its electrical and mechanical performance as 275‐kV cable joint by completion of its assembling test and a long‐term electrical test. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(2): 18–24, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20514     

Power factor improvement of single‐phase diode rectifier circuit by field‐weakening of inverter‐driven IPM motor

This paper proposes a novel inverter drive system to improve the input power factor of single‐phase diode rectifier. Conventional rectifiers need a high‐frequency switching device and a reactor to improve the input power factor. However, the proposed power converter does not need the switching device, electrolytic capacitor, or reactor. By making many ripples across the DC‐bus voltage, the input power factor can be improved. The proposed system consists of only a single‐phase diode rectifier, small film capacitor, three‐phase inverter, and motor. The proposed system adopts an interior permanent magnet (IPM) synchronous motor. The IPM motor is well known as a high‐efficiency motor and can realize field weakening. The basic ideas of the inverter control method are based on the following operations: the inverter's controlled synchronous with the DC‐bus ripple voltage by field‐weakening method, and direct active power feeding from the source side to the motor without smoothing the DC‐bus voltage. This paper describes that the proposed method can obtain an input power factor of 97.3% by experimental tests, and realizes the goals of small size and long life of the system. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(2): 66–73, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20047