| 摘要 |
PROBLEM TO BE SOLVED: To prevent the inverter gain from increasing even if the command voltage is saturated by varying the voltage bias to sustain a specified ratio of the half period mean command voltage before and after voltage saturation processing. SOLUTION: When a modulation factor S(Mi) is determined, an adder 206 produces the difference (2-Mi) between a modulation factor Mi outputted from a modulation factor calculating means 201 and a value 2 from a circuit 206. A limit voltage calculating means 207 calculates the product of a maximum voltage Vlimit 204b and the difference (2-Mi) and delivers the product, as a limit voltage Vtm, to a three-phase command voltage-limit voltage decision unit 208. The three-phase command voltage-limit voltage decision unit 208 makes a decision whether the instantaneous level of each phase voltage overflows the limit voltage Vtm usinq the Vtm as a reference level. According to the arrangement, a current overshoot phenomenon due to an overcorrection voltage can be avoided. |
