Optimization of a Cascaded H-Bridge Inverter for Electric Vehicle Applications Including Cost Consideration

Abstract

This paper presents a method to find the optimal configuration for an electric vehicle energy storage system using a cascaded H-bridge (CHB) inverter. CHB multilevel inverters enable a better utilization of the battery pack, because cells/modules with manufacturing tolerances in terms of capacity can be selectively discharged instead of being passively balanced by discharging them over resistors. The balancing algorithms have been investigated in many studies for the CHB topology. However, it has not yet been investigated to which extend a conventional pack can be modularized in a CHB configuration. Therefore, this paper explores different configurations by simulating different switch models, switch configurations, and number of levels for a CHB inverter along with a reference load model to find the optimal design of the system. The configuration is also considered from an economically point of view, as the most efficient solution might not be cost-effective to be installed in a common production vehicle. It is found that four modules per phase give the best compromise between efficiency and costs. Paralleling smaller switches should be preferred over the usage of fewer, larger switches. Moreover, selecting specific existing components results in higher savings compared to theoretical optimal components.

Trends and Challenges in Multi-Level Inverter with Reduced Switches

“…Proposed structure is named as cascaded switch-ladder inverter (CSLMLI). The output voltage of SLMLI (Vout) is equal to the sum of output voltages of all the SLMIs and it is given in Equation (1). In order to increase the number of levels further, using proposed switched ladder inverter, it leads to increase the component count which makes the system bulky, costly, and complex.…”

“…Nowadays, multilevel inverters (MLI) play a major role in various power applications such as Electric Vehicle [1], Photovoltaic systems [2], Low-Power Loads [3], Grid integration system [4]. It is more attractive because of very low harmonic distortion, low number of drivers, absence of filters, low installation area, reduction in voltage stress and switching losses.…”

Switching Frequency Effects on the Efficiency and Harmonic Distortion in a Three-Phase Five-Level CHBMI Prototype with Multicarrier PWM Schemes: Experimental Analysis

“…Among classical and new topology structures of MPIs, the CHBMI stands out in particular for its modular structure, high flexibility, and intrinsically fault-tolerant capability. Moreover, in many applications where the DC sources are naturally separated, e.g., Photovoltaic (PV) systems and vehicles propulsion, the CHBMI is particularly fascinating since it allows easy expansion and reconfiguration of the PV plant or the battery package, also in fault condition [13,14]. Furthermore, the CHBMI performance is a function of the modulation strategy employed, especially regarding the efficiency and the harmonic content in the output voltage and current waveforms [15,16].…”

Reconfigurable Cascaded Multilevel Converter: A New Topology For EV Powertrain

“…However, the possibility of using a single converter submodule for each battery cell has been very rarely considered because of the high number of switches required, which consequently leads to very large conduction losses. Indeed, in [10] the best number of submodules per phase is found to be between 3 and 4.…”