| 摘要 |
PURPOSE:To make an operation of motor always at a prescribed margin angle of commutation regardless of a value of armature current, by means of providing a position detecting signal correction circuit that comprises a multiplier for multiplying a signal, corresponding to the armature current, and a signal, for detecting a phase voltage. CONSTITUTION:A phase voltage of synchronous motor SM, driven by a power rectifier 1 and a power inverter 3, is detected by a transformer 4, being given to a position detecting signal correction circuit 9 through a filter 5, and the phase voltage and a current reference are multiplied by a multiplier 21, being fed to a positive-negative polarity detector 24 through an adder 23, and this output is to be made with a gate pulse given to a thyristor of the power inverter 3 through a logical signal conversion circuit 6 and gate logical circuit 7. Accordingly, a setting can be made by a variable resistor 22 so that a margin angle of commutation may be constant at both operations of no load and rated load, resulting in no more necessary margin angle of commutation taken at the time of light load, with a better output characteristic of the motor obtainable. |
