A Vector-Signal-Based Analysis for Salient Synchronous Motors Oriented to Energy-Efficient Current Controls

Electrical Engineering Japan

2006

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SUMMARYThis 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.

Section: ) Temperature Characteristics Are Ignoredmentioning

confidence: 99%

A new investigation of dynamic mathematical model of synchronous reluctance motor—A simple unified analysis of model characteristics

Electrical Engineering Japan

2006

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“…The control scheme to issue current commands based on the minimum total copper loss can be treated as an optimization problem of generating the desired torque τ/N p = c τ under the constraint that the exciting current and q-axis current must be set so as to minimize the total copper loss p w . Thus, consider the following Lagrangian with Lagrange coefficient λ [19]:…”

Section: Trajectories and Characteristics Of Current Solutions For MImentioning

confidence: 99%

“…Assuming that the squared limit voltage is c v 2 , determination of the maximum-torque current command may be treated as an optimization problem of maximizing the generated torque subject to the voltage limit [19]. Thus, consider the following Lagrangian with Lagrange coefficient λ…”

Section: Trajectories and Characteristics Of Optimal Current Solutionmentioning

confidence: 99%

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Optimal current control methods of a non-salient pole hybrid field-synchronous motor for energy-efficient and wide speed-range operation

Sagawa

2006

Elect. Eng. Jpn.

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SUMMARYThis 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 energyefficient 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.

“…An example of Trajectory Theorem I based relationship between an optimal trajectory, stator current, and reference frames. (58) (20) (57) PMSM 1 (20) PMSM (58) …”

mentioning

confidence: 99%

A New Unified Analysis of Estimate Errors by Model-Matching Phase-Estimation Methods for Sensorless Drive of Permanent-Magnet Synchronous Motors and New Trajectory-Oriented Vector Control, Part II

2007

IEEJ Trans. IA

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This paper presents a new unified analysis of estimate errors by model-matching extended-back-EMF estimation methods for sensorless drive of permanent-magnet synchronous motors. Analytical solutions about 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 realize directly quasioptimal strategy minimizing total losses with no additional computational loads by simply orienting one of 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 model-matching extended-back-EMF estimation methods.Some of main analytical results will be summarized as following theorems.Error Theorem I Let ∆R 1 , ∆L qd , ∆L q be stator parameter errors. If rotor phase is estimated using the stator parameters with errors by one of the model-matching extended-back-EMF estimation methods, then the following phase estimate error results in