Influence of multilevel sinusoidal PWM schemes on the performance of a flying-capacitor inverter

Abstract

Multilevel inverters, including the flying-capacitor topology require more complex control due to the additional flexibility offered by the multiple output voltage levels. One such control method is based on the conventional sinusoidal pulse width modulation (SPWM) scheme and uses multiple triangular carriers. There are a number of SPWM variants that achieve the desired inverter control. This paper presents the results of an investigation into these different schemes and their influence on the power quality and efficiency of a flying-capacitor inverter.

Multilevel space vector PWM control schemes for a flying-capacitor inverter

“…If the sum of the conducting periods over several inverter cycles for each intermediary switching state is equal, then balanced operation is achieved. One method for achieving this is to use a BALANCING CLOCK which has a period which is a prime number multiple of four operating cycles in the four level inverter case [8]. The logic block diagram is shown in Figure 10.…”

Carrier-based sinusoidal pulse-width modulation techniques for flying capacitor modular multi-level cascaded converter

“…Currently, MMCCs are mainly controlled by sine-triangle PWM [22,23,24,25,26,27,28,29,30,31,32] schemes because of their simplicity in implementation and good waveform quality. Typical ones include the phase shifted PWM (PS-PWM), the phase disposition PWM (PD-PWM) and their variants such as phase opposition disposition (POD), alternative phase opposition disposition (APOD) PWMs [33]. Extensive work has been done in applying the basic two methods for MMCCs having either 2L-HB or 3L-FB as the basic sub-modules, and it has been established that PD-PWM is the most preferred technique due to its resultant low power losses and good waveform quality [31].…”

Investigation of sensorless capacitor voltage balancing technique for modular multilevel converters

“…Different control schemes, and modulation strategies for MMC are also presented in [7]- [9], and [10] respectively. The most popular modulation strategies for MMC are phase-disposition (PD) [1], shifted-carriers [11], and selective harmonic elimination [12].…”

“…In [11], a self-balancing technique for flying capacitor multilevel converters is introduced for PD and shifted-carrier modulation techniques. This was achieved by adding a simple logic circuit between the PWM generation block and the gate drivers.…”