| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to generate PWM signals by simple calculations, to increase control accuracy and to improve the utilization factor of a DC power supply for a three-phase AC load by performing computation for generating PWM signals, based on a given combination of several kinds in total of voltage basic vectors including a zero vector. SOLUTION: When receiving voltage command signals Vm, Vt from a current control circuit, a rotation/standstill coordinate transforming circuit 7 converts the signals into Vα , Vβ , which are inputted into a PWM computing circuit 8 to make computations A, B, C. Then, it is judged whether they are positive or negative by referring to the contents of a table stored in a RAM 9. Based on this result, kinds of voltage basic vectors and pulse width, etc., are computed for every phase range. PWM signals generated based on the computation are outputted to each of switching elements G1 to G6 of an inverter circuit 1. The switching elements G1 to G6 are controlled with PWM to output phase voltages and line voltages from the inverter circuit 1. |
