| MS Seminar

Name of the Speaker: Mr. SWAPNIL TRIPATHI (EE22S009)
Guide: Prof. Srirama Srinivas
Venue: ESB 234 (Malaviya Hall)
Date/Time: 9th October 2024 (Wednesday), 3:30 PM
Title: Capacitor Voltage Balancing PWM methods for a Single DC Source Driven Cascaded Three-level Inverter Drive

Abstract :

Variable frequency variable voltage supply is recommended for motor control for energy conservation. Inverter drives can output variable voltage variable frequency ac power. The quality of output voltage can be enhanced with the use of multilevel inverters. Three-level voltage space vector can be synthesized using two cascaded two-level inverters. Traditionally, the cascaded three-level inverter topology demands two isolated DC power sources for operation.

This talk introduces two carrier-based pulsewidth modulation methods for the cascaded three-level inverter supplied from a single DC power source by thoughtfully balancing the input DC-link capcaitor voltages of the drive system. The first method is a carrier-based pulse width modulation (CBPWM) technique that involves injecting a suitable offset voltage into the sinusoidal modulating signals. This approach is designed to effectively manage neutral-point voltage fluctuations and thus eliminates the necessity for two isolated DC power sources. Deviating from the traditional approach, the second method proposes the carrier-modified PWM approach wherein the carrier signals are adjusted using offset voltages according on the deviations in the DC-link capacitor voltages. The equivalence between the two PWM methods will also be discussed.

The talk also presents simulation and experimental results to demonstrate their efficacy in driving induction motor load across a wide speed range using a single DC source. The proposed PWM techniques simplify the power supply requirements and enhance load current performance, as evidenced by improved Total Harmonic Distortion (THD) profiles.