AC voltage generation in rail applications (auxiliary services), usually employs optimized PWM feedforward schemes in order to control the inverter. In this kind of applications the THD reduction of the filtered output voltage together with the reduced weight of the static converters are the main goals to be reached. In order to achieve these objectives, the most commonly used optimized PWM techniques are going to be compared and an improved modulator is proposed. The theoretical comparison as well as the modulator performance has been validated experimentally.