| 摘要 |
<p>PURPOSE:To eliminate the necessity of a voltage detecting transformer by calculating a DC output voltage and a phase control signal of a thyristor Leonard device and detecting the voltage of a main AC power source of the Leonard device. CONSTITUTION:A phase control circuit 14 inputs a current signal outputted from an automatic control circuit 10, a voltage signal VD and a phase control signal VPHC in response to the speed signal, calculates the cos<-1>, and applies the gate pulse signal 15 of phase delay alpha to a thyristor converter 2. A voltage detector 16 multiples VD/VPHC outputted from a divider 18 by a coefficient K, and applies the output to a memory 24. A current continuous detector 22 outputs a timing signal 12 of ''1'' when the current signal IA is the prescribed value or higher and the signal 12 of ''0'' when the prescribed value or lower, and the memory 24 outputs the signal 21 as it is when the timing signal 23 is ''0'', and the signal 21 immediately before becoming ''1'' from ''0'' when ''1'' as the voltage signal Va.</p> |
