| 摘要 |
<P>PROBLEM TO BE SOLVED: To dissolve the demerit of a conventional system that two detection systems are required to detect step out, since the system judges step out in case that the arithmetic value of the quantity of axial slippage from a revolution command is over a reference value and that the system is provided with a function of judging the existence of step out of a motor by calculating the reactive power of the motor from the applied voltage of the motor and the detected value of the current, and the control becomes very complicated and it requires a very high-performance microcomputer and a large quantity of memory. <P>SOLUTION: When driving an inverter by outputting such a voltage vector that a d-axis current being the exciting current component of a current flowing to a motor may come to the target value without using a position sensor for detecting the position of a rotor, this unit changes the target value of the d-axis current periodically and detects the step out by the response of the q-axis current. Moreover, it applies braking torque to a rotor in rotation by outputting a voltage vector which brings on three-phase short circuit at start so as to decelerate the rotor and fix the rotor position, and in case that the current generated at that time reaches the level of demagnetization, it quickly stops the current application. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
