This paper surveys some notable efforts on improvement of position sensorless control of interior permanent magnet synchronous motors and synchronous reluctance motors. These motors are widely utilized for saving energy and for their high power density, and the control techniques for these motors have advanced to address recent trends in motor development. This paper focuses particularly on the position estimation and current control techniques developed in Japan for motors with considerable magnetic non-linearity and demonstrates solutions that have been proposed for improvements in the performance of position sensorless control.

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This paper deals with the innovative application technologies on variable speed AC motor drive systems. These application technologies are categorized on the basis of the advantages of the AC variable speed motor drive systems, such as downsizing, packaging with high density, energy savings, better availability and maintenancebility, higher controllability of the torque and speed, load leveling. Various component technologies such as the power conversion technology, control technology, and motor technology are also mentioned along with their related application technologies. Future perspectives of the ac drive application technologies are discussed in the conclusion of the paper.

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This paper proposes a parameter measurement method for interior permanent magnet synchronous motors that uses an unknown input observer for maximum-torque-control-frame-based position sensorless control. In position sensorless control, accurate motor parameters are required for rotor position estimation. Hence, these parameters need to be tuned in prior to the realization of position sensorless vector control. Generally, the mathematical model in the d-q axes needs to hold for the parameter measurement. This model in the d-q axes cannot hold, however, since accurate position estimation is impossible even if any pre-proposed position observers with inaccurate parameters are applied. The authors have already proposed a rotor position estimation method that uses an unknown input observer, which can help to realize significant robustness with respect to parameter mismatches. This paper proposes a parameter measurement method with assistance of the robustness of the unknown input observer of the previously proposed method. Finally, some experimental results demonstrate the feasibility and effectiveness of the proposed method in terms of maximum torque development.

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A simplified sensorless vector control system is derived by using the extended electromotive force (EMF) model. By using a steady-state voltage equation approximately, the rotor speed and position are computed from the output voltage of a γ-axis proportional plus integral (PI) current controller with decoupling control. A linear model is proposed for the small perturbation around a steady-state operating point. The system stability is discussed in terms of the trajectories of the system matrix eigenvalues for speed estimation and control parameters. The comparison between the simulation results obtained using a nonlinear model and the experimental results validates the derived system.

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This paper presents a modeling approach for describing the dynamics from the fuel injection command of individual cylinders to the oxygen sensor output in spark-ignition multicylinder engines. In the presented approach, it is shown that the dynamics can be modeled as a single-input, single-output, periodic time-varying system, in which the periodicity is attributable to the cyclically physical phenomenon of the engine system. Furthermore, as compared to the conventional air-fuel ratio model, the proposed model provides the characteristics of the air-fuel ratio in a small-scale sampling rate under individual cylinder fuel injection. To demonstrate the effectiveness, numerical simulation results are presented, and finally, experimental validation is provided on the basis of the results of the identification tests conducted on a six-cylinder gasoline engine control test bench.

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This paper discusses a high-efficiency AC-DC converter developed for implementation under low-voltage and high-current conditions for sintering applications. First, the circuit configuration and the control principle for the proposed low-voltage, high-current AC-DC converter are described. The proposed system consists of four 2,500-A units of the AC-DC converter connected in parallel. The input current harmonics are suppressed by using multiple transformers on the input side. Further, imbalance issues in the transformer parameters and the output wiring are discussed. The proposed system demonstrates that each individual circuit yields a balanced 2,500-A output. In addition, loss analysis shows that the power loss on the secondary rectifier is 49% and is dominated by semiconductor loss. Furthermore, it is shown that by implementing a MOSFET synchronous rectifier, instead of a Schottky barrier diode, the loss reduces by 35%. Finally, the input current harmonics are reduced by using multiple transformers, and the validity of this result is demonstrated.

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This paper presents a design procedure for fractional-slot, three-phase tubular linear permanent magnet machines. The machine has a solid iron mover and stator core, concentrated prewound stator windings, and rare earth annular magnets with axial magnetization. The stator winding interacts with the mover magnets through the fifth harmonic of its magneto-motive force distribution. The proposed design procedure analytically determines the proper dimensions of basic geometry. A finite element method optimization of the air-gap flux density profile focusing on the shape of slots, teeth, and polar expansions completes the design procedure. The study evaluates the effectiveness of the solid iron fractional slot tubular machine for low-speed applications. Experimental verifications are included.

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In this paper, a novel force sensing method is proposed to achieve a wideband force control system with friction-free and noise-free observation. The effect of friction on force observation is eliminated owing to the addition of a periodic signal to the desired reference signal. A high-order disturbance observer and a Kalman filter are used for the force-sensing operation to reject the oscillatory disturbance and to suppress the noise in force estimation. In consequence of effective noise reduction using the Kalman filter, the force sensing bandwidth improves radically. Additionally, all the control algorithms are implemented in a field-programmable gate array (FPGA) with a high sampling rate; the FPGA enables the widening of the bandwidth of the force control system. The effectiveness of the proposed method is verified by experimental results.

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