A method of treating a catalyst support comprises introducing onto andor into an untreated catalyst support which is partially soluble in an aqueous acid solution andor a neutral aqueous solution, Si, Zr, Cu, Zn, Mn, Ba, Co, Ni andor La as a modifying component. The cavity may generally extend from crown to sole or, in the alternative, extend only a partial amount of the distance from the crown to the sole. Namely, the same state quantity of the alternating-current motor is used in the motor control in both the rectangular-wave voltage control mode and the PWM control mode.