| 摘要 |
PURPOSE:To eliminate the effect of the fluctuation of the primary winding power supply voltage and at the same time to obtain the voltage proportional to the speed, by applying the addition and subtraction to the voltage proportional to the secondary voltage of a motor and the voltage proportional to the primary winding power supply voltage. CONSTITUTION:The voltage proportional to the secondary voltage E2 of a wound-rotor type motor IM is detected by a transformer TR2 and then applied to an adder/subtractor circut AD after receiving the rectification through a rectifier D2. On the other hand, the voltage proportional to the primary winding power supply voltage Vs is detected by a transformer TR1 and rectified by a rectifier D1 to be supplied to the circuit AD as a bias via a variable resistor RB. The voltage E2 and the output voltage EDC of the rectifier D2 have the linear change to the change of the speed N but are not proportional to the speed. In this connection, the voltage EDC is converted to be proportional to the speed N. Accordingly the output voltage VD of the circuit AD becomes proportional to the speed N. |
