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This paper proposes a new sensorless vector control method for energy-efficient and wide-speed-range drives of permanent-magnet synchronous motors. The proposed sensorless method has the following features: 1) wide-speed-range drive under voltage limit; 2) current limitation; and 3) high efficiency. These features are realized in a very simple manner and can operate adaptively in all sensorless driving modes, including motoring/regenerating and steady/transient states. The usefulness of the proposed method is verified by extensive experiments. [ABSTRACT FROM PUBLISHER]

This paper investigates and proposes new system structures for vector control of permanent-magnet synchronous motors (PMSMs) with core loss. The proposed vector control systems have the following versatile features. (a) The systems employ the structures allowing control of the stator current through control of the load current. (b) The systems employ unique “stator voltage feedback-use” structures in order to accomplish simply the load current control. (c) The produced torque is directly related to the load current, and the precise torque control can be attained through the load current control. (d) The relation between produced torque and the load current is nonlinear for salient-pole PMSMs similar to the case of no core loss, and a variety of the load current commands can be selected from viewpoints of minimum loss and/or wide speed range drives. The system structures add no constraint to the selection of the load current commands. (e) In addition to the torque control, the speed control can be allowed, where linearity between output of the speed controller and produced torque is kept. The validity of versatile features is verified through the numerical experiments. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(3): 28–39, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20910 [ABSTRACT FROM AUTHOR]

This paper presents a new unified analysis of estimate errors by model-matching phase estimation methods such as rotor-flux state observers, back EMF state observers, and back EMF disturbance observers, for sensorless drive of permanent magnet synchronous motors. Analytical solutions for estimate errors, whose validity is confirmed by numerical experiments, are rich in universality and applicability. As an example of universality and applicability, a new trajectory-oriented vector control method is proposed, which can directly realize quasi-optimal strategy minimizing total losses with no additional computational loads by simply orienting one of the vector-control coordinates to the associated quasi-optimal trajectory. The coordinate orientation rule, which is analytically derived, is surprisingly simple. Consequently, the trajectory-oriented vector control method can be applied to a number of conventional vector control systems using one of the model-matching phase estimation methods. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(1): 52–65, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20801 [ABSTRACT FROM AUTHOR]

This paper proposes a new sensorless vector control method for salient-pole permanent-magnet synchronous motors. With regard to phase estimation, the sensorless vector control method is featured by a new high-frequency voltage injection method (i.e., carrier modulation method), which is distinguished from the conventional ones by a unique ellipse shape of spatially rotating high-frequency voltage, and by a new phase-locked-loop method as a demodulation method whose input is a high-frequency current component multiplied signal. The new vector control method established by two innovative technologies for modulation! demodulation can have the following high-performance and at- tractive characteristics. 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) Phase estimation is robust against inverter dead time, and proper phase estimate can be obtained even under circumstances where stator current crosses the zero at high frequency. 5) Computational load for estimating rotor phase is very small. Usefulness of the proposed new vector control method is verified through extensive experiments. [ABSTRACT FROM AUTHOR]

This paper presents a new characteristics analysis of a dynamic mathematical model for synchronous reluctance motors, which is recently attracting attention in conjunction with the problem of rotor phase selection and estimated based on the extended BEMF (back electromotive force) for sensorless drive. This paper gives the following new characteristic results in a simple unified analytical manner. (1) Change between positive and negative salient pole phases requires basically no modification to the dynamic mathematical model in the general reference frame. (2) Selection of positive or negative salient pole phase as rotor is no more than a preference of designers. (3) There exists a very simple method of deriving two stator flux models for explicit expression of the extended BEMF. (4) At least four circuit equations with the extended BEMF exist, which are equivalent to each other on the same reference frame. (5) There exists duality among the four circuit equations from the viewpoints of rotor phase selection. (6) The duality reinforces the above-mentioned five results. Main results of this paper correct or reinforce the results recently reported by others. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(1): 69–75, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20244 [ABSTRACT FROM AUTHOR]

This paper proposes new practical optimal current control methods for a newly emerging class of non-salient pole synchronous motors with hybrid rotor fields by both permanent magnet and winding. In practical situations with limited voltage, the extensively used permanent magnet synchronous motor hardly achieves an ideal performance that allows simultaneously both low-speed high-torque and wide speed-range operations, due to its constant magnet field. Hybrid field synchronous motors (HFSM) have recently emerged to achieve ideal performance as practical motors with controllable hybrid rotor field. For HFSM, the same torque can be produced by a variety of currents due to nonlinearity between torque and currents. Consequently, appropriate determination of a set of stator and rotor current commands plays a key role in achieving possible energy-efficient and wide speed-range operation. Proposed methods determine the current commands corresponding to a given torque command such that total winding copper loss due to stator and rotor currents can be minimized if the exact solution exists; the best approximate torque can be produced if no exact solution exists. The determined current commands are optimal in the sense of energy efficiency or degree of approximation in wide speed-range operation under voltage limit. New real-time recursive algorithms searching the optimal current solution are also given. The proposed methods are analytical but practical, and their usefulness is verified through experiments. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(1): 70–83, 2006; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20156 [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

This paper proposes new mathematical models of an induction motor that generates torque precisely under vector control. The proposed models for the controlled motor have desirable features in respect to preciseness and compactness. They guarantee the same relation between the stator voltage and current signals as does the conventional T-type model consisting of five parameters. The number of parameters forming the new models is reduced to four, such as stator resistance, inverse of rotor time constant, stator inductance, and stator total leakage inductance, or another set of four related uniquely to them. The parameters are uniquely determined by the stator signals, in terms of which all controller parameters of the vector control system can be designed. ©1998 Scripta Technica, Electr Eng Jpn, 126(2): 48–55, 1999 [ABSTRACT FROM AUTHOR]