A method of generating electricity by an alternator and a generator is disclosed. The method includes: connecting in series stator coils of two multi-pole permanent-magnet generators that can generate equiamplitude alternating currents of different frequencies to generate equiamplitude alternating currents of different frequencies that are superimposed to generate an amplitude-modulation alternating current with envelope lines having an amplitude that changes with a voltage difference between two equiamplitude alternating currents; rectifying the amplitude-modulation alternating current positively and negatively through a controllable rectifying circuit; and filtering to output an alternating current having frequency of the envelope lines. An alternator according to the present disclosure has not only all the advantages of the existing inverting generator, but also a manufacturing cost consumedly lower than the existing inverting generator, even lower than a general universal generator, without the high-frequency electromagnetic wave, thus meeting the existing European EMC certification requirements.