This paper proposes a current control method based on the state space model for magnetically coupled double three-phase interior permanent magnet synchronous motor (IPMSM). The proposed independent current control method modifies voltage reference using the calculated coupled components between the axes and between the windings by using the state space model. When the voltage reference saturates due to a sudden change in current reference, decoupling control between windings becomes insufficient. The proposed voltage limit method and anti-windup control then reduce the coupled components between windings even under voltage saturation. The effectiveness of the proposed control method was verified by conducting dynamic experiments. The proposed current control method has no overshoot and can effectively reduce oscillatory current due to magnetic coupling.

Microwave ovens (MOs) are commonly used for cooking and heating food; it uses microwaves with frequency in the 2.4GHz band, which is one of the ISM band. However, discharge could occur inside the MO due to the formation of the high electric field by the microwaves when the tableware made of metal or decorated by metal paint, or when aluminum foil is placed inside a MO under operation. In addition, if there is food residue or food that generates flammable gas, the discharge may trigger severe ignition or combustion. Therefore, the discharge signal should be detected during the MO operation to avoid fires or accidents caused by the discharge. From this safety viewpoint, this paper described the detection properties of discharge-emitted electromagnetic (EM) waves leaked from inside the MO by using a Horn antenna placed outside the MO with a low pass filter (LPF) for eliminating the leaked microwaves. The light emission properties of the discharge, including ignition and combustion during the MO operation, were also investigated along with the discharge-emitted EM waves. As a result, it was confirmed that the discharge-emitted EM waves can be detected with the first light emission in all the tests by using the antenna with the LPF.

In noise suppression control that switches between two inverters with opposite phases, the synchronization accuracy of switching limits the noise reduction and bandwidth. To improve the noise suppression control, this paper proposes a control method that detects the rise and fall of the inverter output voltage and compensates for the synchronization error between two inverters. The effectiveness of the proposed method was verified by applying it to the double-three-phase motor drive system; the synchronization error was reduced to 10ns.

A power flow controller (PFC) that realizes flexible power flow control in DC power networks is investigated herein. In previous studies, an additional node called a compensation node was introduced in PFC. This compensation node is necessary for regulating the link voltage that decreases owing to circuit loss. However, as the compensation node is not directly related to the power flow control, adding the compensation node may increase the cost. In this paper, we propose a link voltage control method for PFC without the compensation node. Adding the current command for the link voltage control to the current command for the power flow control makes it possible to realize flexible power flow control and constant link voltage control without the compensation node. The effectiveness of the proposed method is verified experimentally.

Actuators with characteristics such as light weight, a high torque/weight ratio, and a high torque control performance are desired for contact tasks using robots. Although electromagnetic motors with gears have these features, friction in gears degrades the torque control performance. Therefore, in this study, the load torque control performance is improved by utilizing motor/load side angle information. Both the torque controller and the load torque observer in the proposed control system utilize motor/load side encoders and the spring model, which includes a dead zone. The dead zone model represents the backlash between the motor output shaft and the reducer output shaft. A simulation and experiment show the efficacy of the proposed control system.

Permanent magnet synchronous motors (PMSMs) are widely used in various applications as high-power-density and highly efficient drive sources. However, a PMSM generates electromagnetic vibration because of the space and time harmonics. In this paper, we propose a synchronous PWM control method for shifting the carrier wave phase against the modulated wave. As the proposed control matches the ripple frequencies caused by the spatial and time harmonics, the ripple caused by the space harmonics is canceled by that caused by the time harmonics, with the phase shift of the carrier wave. The phase shift of the carrier wave is confirmed experimentally. In addition, it is experimentally verified that the vibration of the proposed method at a specific frequency is reduced by 46%@7,900r/min and 53%@19,500r/min.

This paper carries out the efficiency and power density evaluations of a bidirectional non-isolated dc-dc converter based on flying-capacitor converters using Pareto optimization method. The converter consists of a main converter with four power devices and an auxiliary converter which is formed by cascaded chopper cells. A converter design method is proposed, and the relationship between the carrier frequencies of the main and auxiliary converters, the number of chopper cells, and the efficiency and power density of the converter are analyzed quantitatively based on Pareto optimization method. Consequently, it is revealed that the maximum power density can be achieved when the number of cells is four. The validity and effectiveness of the design method presented in this paper are verified using a 200-V, 1-kW down-scale model. Further, the efficiency and power density evaluations of an actual dc-dc converter system rated at 100kW are carried out using numerical analysis based on the “MATLAB” software package and computer simulation using the “PSCAD/EMTDC” software package.

Because the interior permanent magnet synchronous motor (IPMSM) is one of the most efficient motors, it is applied to many industrial machines. The electromagnetic characteristic of IPMSM is dependent on many design parameters such as the position and shape of flux barrier, the magnetization angle of permanent magnet, the current phase angle and so on. The topology optimization (TO), which is an attractive method due to the wide design range with high degree of freedom, has been applied to the rotor design of IPMSM. In this paper, two stage TO method is proposed. Firstly, to widely search the rotor structure, the density method (DM) which handling gray scale is carried out. Next, the obtained structure is set to the initial structure of level-set method (LSM), the local search is carried out. The performance of proposed TO method composed of DM and LSM is compared with the single TO method (DM or LSM) in the design problem in which the object is the determination of the rotor structure composed of permanent magnet, rotor core and flux barrier to improve the torque characteristics and the magnet demagnetization.

This paper proposes a passivity-based stabilization control of a converter in a DC power supply system using feedforward control to improve output frequency impedance characteristics that satisfy the Nyquist stability criterion. The principle is that the output impedance is designed to be passive, and the system is sufficiently stable for any filter impedances. The new design principle for the proposed stabilization method consists of four steps. First, the state feedback control gains with a mitigated integral compensator are designed to possess a good response characteristic according to the optimal control. The designed characteristic of the output impedance may not be passive at a lower frequency band due to an essential characteristic of an integral compensator. Second, the integral characteristic is modified and a resistive characteristic is added to the band by a new feedforward control design based on a fitting method to make the total characteristic passive and to ensure stability. Third, the correction coefficients are tuned to eliminate a deviation between the measured and reference output voltage values at transient operations. Finally, the system passivity is re-checked, and a resistive characteristic is re-added using the feedforward control design if a non-passive band exists. The effectiveness of the proposed method to render the system passive and stable is investigated and validated using simulated and experimental results.

A power conditioning system (PCS) with a single-phase power supply requires a large-capacity electrolytic capacitor in the DC link to keep the input current of the PV panel constant. In addition, the PCS requires an isolated transformer for system safety because of the stray capacitance of PV panels. This paper describes an active power decoupling method using a small-capacity film capacitor. The proposed 3-leg circuit does not require a transformer for isolation, because the input terminal can be connected the output terminal. The experimental results show that twice the grid-frequency components of the input current, which is a power pulsation, is reduced by 91.2%.