Pulse-width modulation signal generating device and method for generating pulse-width modulation signals

In a pulse width modulation signal generating method that generates a pulse width modulation signal formed continuously from a plurality of unit pulse signals while changing a duty cycle by a predetermined duty change rate, where a period of a unit pulse signal formed from a first level and a second level continuous with said first level is a fixed period Tc,

• a pulse width modulation signal generating method comprising the steps of:
• reading, for a phase to be generated, an initial duty cycle, a duty change rate, and a count of unit pulse signals forming said phase from a data storage device that stores a plurality of sets of data of an initial duty cycle, a duty change rate, and a count of unit pulse signals forming a phase for defining individual phases of a pulse width modulation signal;
• multiplying said selected initial duty cycle by said fixed period Tc to calculate a first level generating interval T1 of a first unit pulse signal;
• generating a unit pulse signal, wherein said first level generating interval T1 after said fixed period Tc begins is set to a first level, and a remaining interval in said fixed period Tc is set to a second level;
• and
• calculating first level generating intervals Ta for second and subsequent unit pulse signals by adding or subtracting said selected duty change rate to a duty cycle of an immediately preceding unit pulse and multiplying said duty cycle obtained by adding or subtracting to said fixed period Tc;
• wherein a pulse width modulation signal for one phase is generated by repeatedly executing, by a number corresponding to said selected unit pulse signal count, a step for generating signals that, after executing said reading step and said multiplying step, executes said generating step and then said calculations step.

In a pulse width modulation signal generating method that generates a pulse width modulation signal formed continuously from a plurality of unit pulse signals while changing a duty cycle by a predetermined duty change rate, where a period of a unit pulse signal formed from a first level and a second level continuous with said first level is a fixed period Tc,

• a pulse width modulation signal generating method comprising the steps of:
• reading, for a phase to be generated, an initial duty cycle, a duty change rate, and a count of unit pulse signals forming said phase from a data storage device that stores a plurality of sets of data of an initial duty cycle, a duty change rate, and a count of unit pulse signals forming a phase for defining individual phases of a pulse width modulation signal;
• multiplying said selected initial duty cycle by said fixed period Tc to calculate a first level generating interval T1 of a first unit pulse signal;
• generating a unit pulse signal, wherein said first level generating interval T1 after said fixed period Tc begins is set to a first level and a remaining interval in said fixed period Tc is set to a second level;
• and
• calculating first level generating intervals Ta for second and subsequent unit pulse signals by adding or subtracting said selected duty change rate to a duty cycle of an immediately preceding unit pulse and multiplying said duty cycle obtained by adding or subtracting to said fixed period Tc;
• wherein a pulse width modulation signal for one phase is generating by repeatedly executing, by a number corresponding to said selected unit pulse signal count, a step for generating a unit signal that, after executing said reading step and said multiplying step, repeats twice an execution of said generating step and then said calculating step.