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This paper presents experimental results on a gridconnected inverter. The control of the inverter is based on a virtual synchronous generator model of algebraic type. When using the virtual synchronous generator model of algebraic type, there is no evidence for satisfactory operation with unbalanced load and nonlinear load, because the generator models are constructed under the assumption that the load is linear and balanced. By choosing the feedback control loop gain appropriately, satisfactory operation is achieved even if an unbalanced and nonlinear load is connected. Experimental results show that the power controls, active and reactive, are achieved preferably in grid-connecting mode. Smooth transitions are also achieved from the connected mode to the island mode. The inverter can operate satisfactorily when the unbalanced load is connected. Harmonic analysis is performed with a three-phase fullwave rectifier connected as a nonlinear load. The harmonic current is supplied by the inverter and its output LC filter. It is shown that the harmonic current is supplied mainly by the inverter and that the voltage waveform is acceptable for practical use.

We have developed a precise and high-speed arm applied to assembly processes in electrical product and machine industries. The arm is designed based on the requirement from Japanese major industries. The paper addresses the background of the development, the required specification for the robot arm, and the brief introduction of the prototype arm and evaluations of accuracy. We test the repeatability of parallel mechanism. Then we calibrate the kinematic model of parallel mechanism to improve its absolute accuracy using laser tracking coordinate measuring system.