# An Overview of Non-Isolated Hybrid Switched-Capacitor Step-Up DC-DC Converters
## 5 Hybrid SC Converters
### Traditional SC Converters Modified to Have Resonant Charge Interchange  
Several studies have been dedicated to the use of traditional SC topologies for power conversion with a resonant charge interchange. One example is the ladder converter with  
Figure 27: Other traditional converters and their multiplier version: (**a**) the Cuk converter, (**b**) multiplier Cuk converter [60], (**c**) the SEPIC converter, and (**d**) multiplier SEPIC converter [61].  
the resonant charge interchange shown in Figure 28. Figure 28a shows the 2\(\times\) multiplier (the output voltage is twice the input), while Figure 28b shows the 4\(\times\) converter.  
This converter has been used in several applications, mainly for voltage equalization in a series of capacitors or batteries [102; 103; 104; 105; 106]. The resonant charge interchange can be produced in a traditional SC converter by introducing small inductors in some parts of the circuit.  
The multilevel boost converter, see Figure 26, or multiplier boost converter has also been studied in their resonant charge interchange version [41], see Figure 29.  
A modified version of the converter in Figure 9 has been investigated in [107] (see Figure 30). It consists of a cascaded connection of two converters with convenient modifications to produce a resonant charge interchange.  
Figure 28: The resonant ladder SC converter, (**a**) 2\(\times\) version, (**b**) 4\(\times\) version.  
Figure 29: The Multilevel boost converter with resonant charge interchange [41].  
A modified version of the Series-Parallel converter, see Figure 10, was studied in [44], with a resonant charge interchange, as shown in Figure 31. Figure 31a shows the straightforward converter with thyristors and diodes, while Figure 31b shows a simplified version proposed in [44] with fewer switches but the same operation.  
Thyristors can be used to produce the resonant charge interchange and stop the current automatically when it tries to become negative, particularly useful in very large power applications, such as the one presented in [44] (see Figure 31).  
The Fibonacci SC topology, see Figure 11, was used in [40] with the resonant charge interchange. The contribution included a modified switching sequence that allows performing the resonant charge interchange with a single inductor.  
The Flying Capacitor topology, see Figure 13, has been used as a traditional dc-dc converter, with a stored energy inductor and PWM voltage regulation, and also a SC converter with a resonant charge interchange [30]. Another resonant charge interchange SC converter was recently studied in [108].  
The SC converter shown in Figure 6 was studied with a resonant charge interchange (with a single inductor) in [109], and the topology is shown in Figure 32.  
Figure 31: Thyristors-based implementations of the series-capacitor SC converter with resonant charge interchange, (**a**) straight forward realization, (**b**) a simplified version proposed in [44].  
Figure 30: A resonant version of the converter in Figure 9.  
The MMCC converter, see Figure 15, has been studied in their resonant charge interchange version [110; 111]. In this case, the authors proposed not to use physical inductors, but to use the distributed inductance on the circuit to produce the resonant operation. Other topologies which are different from the traditional have been studied to achieve SC power conversion with a resonant charge interchange [112; 113; 114; 115; 116].