Abstract
The DC tests can predict the operational impedance of rotational machines by a simple standstill test. This paper presents a new DC test using a voltage-source PWM inverter, which does not require a specially assembled DC-power-source unit that is required to perform conventional DC tests. In this paper, three DC tests (DC decay, step response method, and pulse response methods) using the inverter as a power source are discussed. These tests are performed on an air-core reactor and 5.5kW semi-closed squirrel-cage induction machine to verify their validity. In addition, the authors propose an improved DC decay test that can consider the magnetic saturation of the main flux; this test is referred to as the two-step-voltage DC decay test. This test is also carried out on the tested induction machine. Using the test results, the authors demonstrate the calculation of not only no-load saturation performance by considering the magnetic saturation flux but also the starting performance. By comparing between these calculation results and actual measurement data, the authors validate the proposed two-step-voltage DC decay test.
