| 摘要 |
PROBLEM TO BE SOLVED: To output an AC voltage faithful to a command, without changing a switching frequency, also when a voltage command of O vicinity at a low frequency continues. SOLUTION: A gate pulse generating circuit 3 has single phase gate pulse generating circuits wherein each phase is the same constitution. A triangular wave CARL and a triangular wave CARLL whose amplitude and frequency are two times those of CARL are generated. The respective triangular waves are compared with a command value VU. Intermediate pulse commands SUU1, 2 and SUL1, 2 are outputted which are 1 when VU is large and 0 when VU is small. An output pulse command SUU which becomes 1 by the quicker rise out of SUU1, 2 and becomes 0 by the quicker fall out of them. Similarly an output pulse command SUL is outputted from SUL1, 2. SUU and SUL pass gate drive circuits, and four gate pulses containing SUU, SUL and the respective inversion signals ignite/extinguish four ignition control elements of U phase of a main circuit, and executes dipole control when the command is 0 vicinity. |
