Abstract. In consideration of low power density of electric excitation claw-pole synchronous alternator (EECA) and some difficulties in magnetic field regulation of permanent magnet claw-pole synchronous alternator (PMCA), a novel hybrid excitation brushless claw-pole alternator (HEBCA) is proposed in this paper. Its structure and field control principle are described. Three dimensional finite element analysis is used to obtain the no-load magnetic field distributions and field control capability under different field currents. The result shows that the flux of the prototype machine can be adjusted over a wide range with a relatively low field current.

No abstract

This paper provides designers with a useful efficiency design methodology during DC-DC converters system design. Comprehensive power loss analysis for step-up DC-DC converters is presented and a new calculation method of switching loss is proposed. The efficiencies are directly calculated from converter specifications and device parameters. Based on power loss calculation, we have derived optimum design including rectification mode and switching transistor width. The efficiencies after optimum design have been calculated for pulse width modulation (PWM) and pulse frequency modulation (PFM) control. A step-up converter is designed to verify the calculation method.I.