Glossary of Motor Terms
Trapezoidal wave
Voltage and current, which change with time, do not always make sinusoidal waveforms, they sometimes take on forms like those that can be seen in the figure below. (a) and (b) in the figure below are trapezoidal waves that are leading or lagging behind each other by 120 degrees, i.e, (a) is leading (b), or (b) is lagging behind (a). By taking this difference （subtracting b from a）, we get the trapezoidal wave seen at (c).
