| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a low cost dynamic brake by connecting a nonlinear control resistor with the input connector for a synchronous motor and closing the stator winding thereof via the resistor. SOLUTION: In a frequency converter, where the rectified output from a power supply bridge 4 is connected with a motor bridge 5 via intermediate circuits 22, 24, the intermediate circuits 22, 24 are connected with a brake resistor 58 and a nonlinear brake resistor 60 in series with a brake transistor 62. Upon the occurrence of power interruption or an overspeed state, where an emergency governor is operated, a contact 64 is closed thus closing the stator winding circuit of a synchronous motor 2 via input connectors 38, 40, 42, diodes 52-57 in the motor bridge 5 and the nonlinear brake resistor 60. With such a constitution, dynamic braking of the synchronous motor 2 can be attained at low cost.</p> |
