单相全控桥电阻性负载电路中,晶闸管可能承受的最大正向电压为()<br>·<img src="https://zk.995w.com/lqwvjeImg/04/0489a3690b322a1dbb1c93a17b4d775e.GIF"style="width:23px;height:20px;">U2<br>·2<img src="https://zk.995w.com/lqwvjeImg/04/0489a3690b322a1dbb1c93a17b4d775e.GIF"style="width:23px;height:20px;">U2<br>·<img src="https://zk.995w.com/lqwvjeImg/3e/3edf20ee527cfeb7c69dcaa130aa0f6e.GIF"style="width:15px;height:35px;"><img src="https://zk.995w.com/lqwvjeImg/04/0489a3690b322a1dbb1c93a17b4d775e.GIF"style="width:23px;height:20px;">U2<br>·<img src="https://zk.995w.com/lqwvjeImg/b2/b22a0c4c45d607840afdfc75a820f4a2.GIF"style="width:21px;height:20px;">U2