Power Circle And W Transform In Variable Frequency Drive System Of Double Motor

An AC variable frequency system of double motor, which adopts frequency converters of Danfoss VLT5000 series, is presented in this thesis. In this system, two Ac asynchronous motors are driven by those frequency converters respectively. The intermediate circuits are connected together, so the energy can flow in a circle. But the torque and speed of the shaft of motors cannot be tune at the same time. With the development of technology, computer is hoped to be used to complete the function of this control system. The controllability and the control method are now the problem. In order to analyze these kinds of system and answer these questions, POWER CIRCLE (PC) and POWER VECTOR(PV) were made. Based on that theory, W transform, that is used as a mathematical method in the computer controlled system, has been deduced.