| As a part of the exploratory research subject within the national high technology research and development program (863 program)-"design and manufacture of novel variable-speed constant-voltage permanent magnet wind generator", this paper persents a modular variable-speed constant-voltage permanent magnet wind generator of new type that is used in distributed DC grid. A series of key technological problems that will be confronted in the process of R&D are studied. Then a full set of design method for modular variable-speed constant-voltage permanent magnet wind generator is formed, which provided a new design technology of generator to exploid wind power in large scale.The contents of this paper can be divided into following parts.In first part, modular hybrid excitation generator is mainly studied. Firstly, the structure and principle of hybrid excitation generator are analyzed. Then, a novel modular single-tooth wound winding is proposed to solve the transport and hoisting problems of direct-drive or half direct-drive generator on account of weight and volume. The influence of modular installation gap on the motor's performance is also analyzed. Finally, analyses of pole-slot match for modular structure are carried out to summarize a principle choosing pole-slot match for this structure.In second part, different status of electricity excitation for hybrid excitation generator is analyzed using 3D FEM.The magnetic circuit is simplified.Some parameters are derived. Then, reactance parameter is researched for its structural particularity of modular single-tooth wound winding. The analytical formula of armature reaction reactance is deduced, and the curves of coefficient kpd and kpq are determined through FEM calculations of electromagnetic field. Meanwhile, the influence of fractional harmonic on harmonic leakage resistance for single-tooth wound permanent magnet motor is analyzed, and the harmonic leakage permeability coefficientΣs of common single-tooth wound motor is summed up. Finally, through the verification and improvement by experiment values and calculation results of electromagnetic field for lOkW simulation prototype, the software package of CAD design and calculation for modular arranged hybrid excitation wind generator is developed, which provided a design basis for motors of this type.In third part, technologies to increase power generation are studied. Firstly, the reason and mechanism for generating the cogging torque in modular hybrid excitation generator are researched, and the methods to decrease the starting resistance torque are summarized. Then, the formula of winding end for modular single-tooth wound hybrid excitation generator is deduced. By minished the length of winding ends, motor's loss is decreased, and the efficiency is enhanced. Finally, the generating reason of eddy-current loss in permanent magnet is analyzed, and the expression of the ratio of air gap to permeance for surface-mounted structure with pole shoes is derived. Based on the harmonic theory, the contents of space harmonic are analyzed combined with the calculation results of FEM. The calculation method of eddy-current loss in permanent magnet is summed up, and the decreasing method of eddy current loss is proposed.In fourth part, based on above achievements, a modular variable-speed constant-voltage permanent magnet wind generator of 100kW 100r/min and its voltage stabilizing control system are developed, and the general design criteria of such generator are summarized further. The experiment method of generators of this type is improved, and the experimental platform is built. Those all provided integrated design specification for system development of generators of this structure and larger power in future.
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