Multiphase variable-speed drives supplied from two-level voltage source inverters (VSIs) are, at present, contenders for numerous industrial applications. Various pulsewidth modulation (PWM) methods for multiphase VSIs, aimed at sinusoidal output voltage generation, have been developed using both carrier-based and space-vector approaches. An increased number of voltage space vectors, available for the synthesis of the output voltage, offer greater flexibility for the PWM scheme development, compared to the three-phase case. This paper presents comprehensive analytical analysis and comparison of switching ripple characteristics of two continuous space vector PWM (SVPWM) methods for a five-phase two-level VSI. Considered SVPWM schemes select a different set of four active space vectors per switching period in order to generate sinusoidal output voltages. This paper also presents the evaluation of the flux harmonic distortion factors of the SVPWM techniques. Correlation with corresponding current ripple and total harmonic distortion is established in Part 2 of this paper, where theoretical considerations are verified by simulations and through experimental investigation on a five-phase VSI-fed induction motor drive.