PUBLICATIONS

 This paper analyzes the overvoltage based on a reflected voltage in a motor drive system. The reflected voltage caused by impedance mismatch in the motor drive system results in overvoltage. The double pulsing effect occurs when the oscillation of overvoltage caused by reflected voltage has not decayed before the next pulse arises. The double pulsing effect induces a higher overvoltage than a single pulse, causing electrical stress that leads to insulation breakdown on the motor. The reflected voltage caused by impedance mismatch in the motor drive system is analyzed based on transmission line theory in this paper. The oscillation of reflected voltage is investigated through cable modeling, which considers the impedance and length of the cable. The double pulsing effect caused by reflected voltage is calculated using various factors, including modulation index (MI), modulation schemes, and switching frequency. The region of overvoltage caused by the double pulsing effect is normalized using the voltage vector diagram according to modulation schemes. The overvoltage in a motor drive system is verified through simulation and experimental results.