| 摘要 |
<p>PURPOSE:To permit the proper switching of chopper frequency within whole range from a low notch to a high notch, by a method wherein the chopper frequency is determined based on a notch signal in accordance with a speed signal and a microcomputer notch command. CONSTITUTION:Operators 16a-16d input an electric car speed signal V and output notches for switching a chopper frequency (f) from 1/2f to 1/4f, from 1/4f to 1/2f, from (f) to 1/2f and from 1/2f to (f). Comparators 17a-17d output the signals of 'H' level when a notch command N is lower than the outputs of the operators 16a-16d. A selecting circuit 18 determines the chopper frequency in accordance with the combination of output signals of the comparators 17a-17d. A current rate operating circuit 10 outputs an ON pulse signal and an OFF pulse signal in accordance with the outputs of an ON pulse and OFF pulse generating circuit 20 and the selecting circuit 18.</p> |
