The power losses of transistor chopper system driving a dc shunt motor are considered, and the chopper frequency to maximize the system efficiency is referred. Additionally an inductance which make the ripple factor of the motor armature current the desired value at the optimal chopper frequency is shown.
In the chopper system, there are two types of power losses which depend on the chopper frequency. One type of loss (that is switching loss of power devices _??_≡
Psw_??_) increases, while the other type (that is AC component of copper loss _??_≡
PrAC_??_) decreases, as the chopper frequency increases. In this paper, the two types of losses are approximated to simple equations. When the losses depending on the chopper frequency is limited to above two types, the chopper frequency to maximize the system efficiency is provided by the next equation. (
Psw=2
PrAC) From this equation, a control-law of the chopper frequency and the desired inductance for chopper efficiency are obtained. The chopper frequency to maximize the system efficiency and the effect of the inductance are ascertained by experiments.
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