On-line dead time compensation technique for open-loop PWM-VSI drives

On-line dead-time compensation method using disturbance observer

“…The switching times and voltage drops of the power devices are varied with operating conditions such as the dc link voltage, phase currents, operating frequency, and motor speed [10]. Thus, it is difficult to compensate the dead-time effects perfectly by off-line manners.…”

“…Since both switching devices in each leg are off during the dead time and the output voltage is dependent on the direction of an output current, these cause a distortion of the inverter output voltage, which is called as "dead-time effects" [1]. The distortion of the inverter output voltage affects machine currents, which results in a phase current distortion, torque pulsations, and degradations of control performance [3]- [10].…”

“…Thus, it is difficult to compensate the dead-time effects perfectly by off-line manners. Although an on-line method is proposed in [10], this method needs additional hardware circuits such as a zero crossing detector and a time counter together with off-line experimental measurements to set up a look-up table.…”

“…Also, in the on-line PWM controller, this approach re- quires a minimal amount of software resource as compared to other techniques so that processing power can be reserved for other control scheme. The other is based on a feed forward approach, where the compensating voltages are fed to the voltage references in order to generate a modified voltage [7]- [10]. In [7], the compensating voltages are calculated using the dead time, switching period, current command, and dc link voltage.…”

Space vector analysis of dead-time voltage distortion in multiphase inverters

“…This is especially true around the zero-crossing where an accurate measurement is needed to correctly compensate for the dead-time. In [4] an online dead-time compensation technique is presented, acquiring the additional computation burden to determine the phase angle of currents.…”