Zero cross control for inductive loads
An asynchronous machine —an induction motor— is a transformer with a weird rotating, shorted secondary. All the rules of the transformer apply.
And that means you want to turn on at maximum voltage, not on zero-cross. Because that way magnetization starts with a quarter-wave, and then counter-magnetization follows. And so on. If you started with zero voltage, you had doubled magnetization —voltage-time &quot;eaten&quot;— in the beginning.
That additional quarter-wave from voltage-zero to voltage-maximum evens out only after a few dozen full periods and leads to a current spike on turn-on, as the iron core of the machine is overexcited.