23-Level inverter for electric vehicles using a single battery pack and series active filters. http://dx.doi.org/10.1109/TVT.2012.2186599

Abstract

Cascaded H-Bridge (CHB) multilevel inverters have been conceived as an alternative in the medium voltage drives to reduce THD. However, their main problem is the large amount of isolated power sources required for their operation. An improved variant, known as Asymmetrical CHB (ACHB) inverter, needs less isolated power sources than conventional CHB for the same number of voltage levels generated. Nevertheless, in some specific applications, such as battery powered electric vehicles (EVs), is very important to have only one power source. This work presents a solution to solve the problem, operating some of the H-bridges as series active power filters and using a very small High Frequency Link (HFL). With the solution proposed, only one dc source is required to feed the complete system. The proposed topology uses a 27-level ACHB, which is adjusted to work with only 23 levels. The dc source is of variable type, which permits to control the amplitude of the voltage at traction motor terminals. This work shows some simulations and experiments on a 2kW, 27-level ACHB working with only 23 levels. The concept is being implemented in an experimental, 15 kW, small EV.