Yuji Kudoh

Single to two-phase matrix converter using GaN-based monolithic bidirectional switch for driving symmetrical two-phase motor

In this paper, we present a single to independent two-phase matrix converter (iS2MC) consisting of eight Gallium Nitride (GaN) based monolithic bidirectional switches for the first time. The modulation algorithm for the switches in the iS2MC was designed more easily than that in the three-phase matrix converter. So far, common emitter back-to-back Insulated Gate Bipolar Transistor (IGBT) configuration was used for one bidirectional switch in the conventional iS2MC to drive a symmetric two-phase induction motor. The GaN based bidirectional switches have high breakdown voltage and low specific on-state resistance. The experimental results show that the power conversion efficiency of the GaN-based iS2MC is higher than that of the IGBT-based iS2MC for all the conditions and 7.2 % higher at maximum.

30.5 A GaN 3×3 matrix converter chipset with Drive-by-Microwave technologies

In this paper, we describe a GaN 3x3 matrix converter chipset, which are composed of a GaN integrated bidirectional switching chip and a GaN integrated gate drive transmitter chip using 5.0GHz Drive-by-Microwave technology. The extremely compact three phase AC-AC matrix converter such as a 25x18mm2 is realized by these GaN/Si integrated chips and novel isolated dividing couplers, which duplicate the gate signal with different references for dual-gate bidirectional switches and reduce gate lines and gate drive components by half. The proposed GaN 3x3 matrix converter is significantly more compact than the conventional one that requires numerous power switches, flywheel diodes, photo-couplers, isolated power supplies and gate drivers.

A novel single to two-phase matrix converter for driving a symmetrically designed two-phase induction motor

We propose a novel single to two-phase matrix converter (iS2MC) for driving a symmetrical two-phase induction motor. Matrix converter (MC) technology is already used in industrial applications, but is limited to three-phase induction motor with three-phase power line. The iS2MC, which consists of 8 bi-directional switches, enables a two-phase induction motor to be driven by single-phase power line without smoothing capacitors for the first time. The iS2MC generates independent two-phase voltages controlled by a simple switching algorithm, which is designed to hold the switching state for a period of the output source to decrease switching loss. The two-phase motor driven by iS2MC eliminates start-run capacitors and generates more torque than the three-phase motor. The performance of the iS2MC system with symmetrical two-phase induction motor was confirmed by both simulation and experiment.

Integrated power design platform based on modeling dynamic behavior of GaN devices

We present a novel integrated design platform for power electronics applications with models that well simulate the dynamic behaviors of devices such as current collapse phenomena in GaN devices and impedance-shifts of motors. The platform utilizes five commercial EDA tools and performs multi-physics simulation for power applications by taking inductance and reactance parasitics in PCB into account. Accuracy of the simulation was evaluated on general IPM motor applications and AC/DC converters. The measured and simulated values showed good agreement in both applications. This platform contributes to the reduction of the tremendous amount of trial and errors in designing power electronics applications, especially when introducing new power devices.

Fast simulation of power electronic systems by partitioning, segmentation and caching

This paper describes an implementation and experimental results of a simulation framework for accelerated simulation of power electronic systems. The proposed method for accelerating the simulation exploits the differences in time-constants for different parts of the system by applying partitioning, time-segmentation and caching techniques. The framework is built around industry-standard simulation engines. The acceleration techniques are evaluated on a industrial IPM motor system with driver and controller. The driver includes an electronic circuit consisting of more than one hundred components, which is modelled in SPICE with full accuracy. The experimental results indicate that a significant speed-up can be achieved by the proposed techniques, but results depend heavily on the parameters of the simulation and the required accuracy. For the benchmark simulation scenario, a speed-up of a factor 45 was obtained.

Development of multilayer conducting polymer actuator for power application

In late years many kinds of home-use robot have been developed to assist elderly care and housework. Most of these robots are designed with conventional electromagnetic motors. For safety it is desirable to replace these electromagnetic motors with artificial muscle. However, an actuator for such a robot is required to have simple structure, low driving voltage, high stress generation, high durability, and operability in the air. No polymer actuator satisfying all these requirements has been realized yet. To meet these we took following two approaches focusing on conducting polymer actuators which can output high power in the air. (Approach 1) We have newly developed an actuator by multiply laminating ionic liquid infiltrated separators and polypyrrole films. Compared with conventional actuator that is driven in a bath of ionic liquid, the new actuator can greatly increase generated stress since the total sectional area is tremendously small. In our experiment, the new actuator consists of minimum unit with thickness of 128um and has work/weight ratio of 0.92J/kg by laminating 9 units in 0.5Hz driving condition. In addition, the driving experiment has shown a stable driving characteristic even for 10,000 cycles durability test. Furthermore, from our design consideration, it has been found that the work/weight ratio can be improved up to 8J/kg (1/8 of mammalian muscle of 64J/kg) in 0.1Hz by reducing the thickness of each unit to 30um. (Approach 2) In order to realize a simplified actuator structure in the air without sealing, we propose the use of ionic liquid gel. The actuation characteristic of suggested multilayered actuator using ionic liquid gel is simulated by computer. The result shows that performance degradation due to the use of ionic liquid gel is negligible small when ionic liquid gel with the elasticity of 3kPa or less is used. From above two results it is concluded that the proposed multilayerd actuator is promising for the future robotic applications because it has advantages of high work/weight ratio and in-the-air operation, in addition to advantages of conventional polymer actuators.