选择题：在晶闸管触发电路中，若使控制电压 UC=0，改变　　的大小，可使直流电动机负载电压 Ud=0，使

题目内容：

在晶闸管触发电路中，若使控制电压 UC=0，改变　　的大小，可使直流电动机负载电压 Ud=0，使触发角α=90o。达到调定移相控制范围，实现整流、逆变的控制要求。

参考答案：

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