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     

A new identity dimensional D‐state observer for sensorless drive of permanent‐magnet synchronous motors

A new identity dimensionless D‐state observer whose state variables are the stator reaction flux and rotor flux is proposed for the sensorless drive of permanent‐magnet synchronous motors. Furthermore, sufficient conditions are newly and analytically derived for the observer gains that guarantee stable convergence of state variable estimates. Additionally, two new methods for designing observer gain are presented; these methods, the constant and speed‐dependent gain methods, satisfy the derived analytical conditions. The observer gain conditions used in the design methods are validated through extensive numerical experiments. In addition, typical design examples of the observer gains using the proposed design methods are presented. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(1): 45–61, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21200     

New generalized D‐state observers for sensorless drive of permanent‐magnet synchronous motors. Impact of rotor flux harmonics to fundamental component estimate

This paper proposes new generalized D‐state observers as new minimum‐order flux state observers for sensorless drive of permanent‐magnet synchronous motors. The proposed generalized D‐state observers, which are established by a new approach using filters in the D‐module, contain the conventional D‐state observer as a special case, and the associated observer gain also contains the conventional one for the conventional D‐state observer as a special case. Consequently, the proposed generalized D‐state observers provide designers with a higher degree of design flexibility. In addition, for generalized D‐state observers, this paper presents a new analysis of the error in estimation of the rotor flux fundamental component due to rotor flux harmonics originating from nonsinusoidal magnetization, which has hitherto been an unsolved problem. It is analytically shown and verified by numerical experiments that harmonics appear in the flux estimate in a similar manner to the original rotor flux harmonics from the viewpoint of rotor phase error. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(2): 37–47, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20768     

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 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     

Sensorless salient‐pole PM synchronous motor drive in all speed ranges

This paper presents a position sensorless drive of salient‐pole PM synchronous motors in all speed ranges including zero speed. Two position and speed estimation algorithms using the current differences between the actual and the estimated currents are proposed. One is based on the back emf estimation in the medium‐ and high‐speed ranges. Another is based on the position dependency of the winding inductances in the low‐speed ranges including zero speed. The effectiveness of the proposed algorithm has been verified with a six‐pole, 1.5‐kW, 1500‐rpm test motor. Stable sensorless speed control from zero to 3000 rpm within ±100% load torque range was achieved. © 2001 Scripta Technica, Electr Eng Jpn, 135(3): 64–73, 2001     

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     

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     

A new method for estimating initial rotor phase of self‐excited hybrid‐field synchronous motors

This paper proposes a new method for properly estimating the rotor initial phase (i.e., the position) of the newly emerging self‐excited hybrid‐field synchronous motors (SelE‐HFSMs), which have the rotor held by both a permanent magnet and a diode‐shorted held winding. The proposed method injects a spatially rotating high‐frequency voltage and detects the rotor phase directly by evaluating the norm of the associated current. The method is very simple, but has a high degree of usability. 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(3): 49–58, 2010; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.21027     

A new three‐input/output characteristic‐varying filter in the D‐module for direct processing of three‐phase signals

This paper proposes a new three‐input and three‐output characteristic‐varying filter in the D‐module for direct processing of three‐phase signals, which are becoming indispensable for effective active compensation of three‐phase power such as harmonics current, negative phase current, reactive power, and varying voltage compensations. The filter in the D‐module can show different filtering characteristics to positive, negative, and zero phase components of three‐phase signals and can allow direct processing of the signals based on frequency polarities. The filter in the D‐module can also change dynamically its filtering characteristics by simply injecting a shift‐signal to itself. These filtering effects are obtained in a very simple manner using the D‐module. A new unified analysis of attractive general characteristics of the proposed filter in the D‐module is given for its easy designs and realizations as well. Effectiveness of the analysis and usefulness of the filter in the D‐module are newly examined and confirmed through experiments. The newly proposed filter in the D‐module has potential regarding a variety of three‐phase signal filtering applications. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(1): 28–38, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10170     

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