## 3 Various System Configurations Studied
### Configuration Type III: A Single DCB Source with an FC  
This configuration is similar to the one described in Section 3.1. However, a key difference is that, in this structure, the slave inverter is supplied by a floating capacitor (Type III) instead of a DCB source. This distinction is illustrated in Figure 12.  
In the DTLI with an FC, as illustrated in Figure 12, the voltage ratio between the DCB sources is defined as \(1:x\), where \(x\) is a constant coefficient. In this setup, the master inverter is supplied with a fixed DCB voltage \(V_{dc}\), while the Slave inverter is powered by a floating capacitor that provides a voltage of \(x*V_{dc}\). The capacitor is connected without a fixed reference point, and its voltage is naturally self-balanced based on the system configuration and the applied control strategy. Figure 11: Spatial vector diagram of a DTLI with asymmetrical sources: (**a**) source ratio \(2:1\) and (**b**) source ratio \(3:1\). During the modulation process, the phase currents can flow through the FC, resulting in voltage fluctuations across it. By convention, a current flowing into the Slave inverter is considered positive, and the switching states of the Slave inverter directly influence the current through the capacitor. Since a single modulation vector can be synthesized from multiple switching states, these vectors can be categorized based on their impact on the current flowing through the FC as follows:  
* Type 1 vectors: These vectors induce two opposite current flows within the same phase, such as positive and negative currents in phase \(a\), depending on the specific switching states. * Type 2 vectors: These vectors result in current flow in only one direction within a given phase, for example, only a positive current in phase \(a\). * Type 3 vectors: These vectors produce no current flow through the FC, regardless of the switching states. * Type 4 vectors: These vectors generate current flow in different phases, such as a positive current in phase \(a\) in one state and a negative current in phase \(c\) in another. This classification offers valuable insight into the interaction between modulation vectors and the dynamic behavior of the FC. A more detailed example of the application of these principles is provided in Section 5. This configuration combines the advantages of the other two setups, offering multi-level output voltage and voltage amplification capabilities, thanks to the elimination of ZSV circulation. Additionally, it eliminates the need for an isolation circuit, as one of the inverters is floating. In this DTLI configuration with an FC, the main challenge is regulating the FC voltage to the desired value. Likewise, in DTLI systems with isolated asymmetrical power supplies, a potential concern is that the capacitor on the low-voltage side may be overcharged due to energy flow from the high-voltage side. In summary, each of the three DTLI configurations presents distinct characteristics in terms of performance, complexity, and implementation requirements. The Type I configuration stands out for its structural simplicity and ease of implementation. However, it is affected by the generation of CMV and ZSV, which can degrade the output voltage quality and increase the overall system losses. The Type II configuration eliminates these undesirable effects and enhances modulation flexibility, especially when asymmet  
Figure 12: Configuration of a DTLI powered by a single DCB source with an FC. ric voltage sources are used. On the other hand, the need for galvanic isolation adds to the cost and increases the risk of capacitor overcharging on the lower voltage side. The Type III configuration offers a good compromise by combining the benefits of the two previous structures while eliminating the need for isolation. Nonetheless, it introduces a challenge in regulating the voltage across the floating capacitor, particularly in transient operating conditions.