| 摘要 |
PURPOSE:To make a current concentration not to occur even for a thyristor motor operating both positive and reverse directions by controlling an armature current selecting either sum or difference of an exciting frequency and a revolving frequency corresponding with a revolving speed. CONSTITUTION:A frequency instruction circuit 31 outputs signal corresponding with a revolving speed signal output from a tachogenerator 5 and an oscillator 13 outputs sinusoidal wave signals S1,S2 of either +omegaf or -omegaf corresponding with an output signal of the frequency instruction circuit 31 and of 90 degrees phase different each other. This signal becomes to be a frequency standard of a field current in field windings F1,F2 of a synchronous machine 3. A freqeucny addition circuit 30 processes a sum frequency of an output signal frequency of a position detector 4 and an output signal frequency of an oscillator 13 and its output signal is made to be a frequency standard of an output current of a cyclo-converter 2. By doing in this manner, an armature current frequency is made not to become either zero or a vicinity to zero and a current concentrating phenomenon to a particular thyristor can be prevented. |
