# State-of-the-Art DC-DC Converters for Satellite Applications: A Comprehensive Review
## 3 Review of DC-DC Converters for Satellites
### Non-Isolated Topologies
#### 3.1.2 Boost-Derived Topologies  
A boost converter is predominantly used to implement MPPT on satellites. For instance, the Bepicolumbo mission to Mercury used a boost converter (12 kW, 100 V bus) for implementing MPPT [79]. Various boost-based topologies for satellite applications were compared and analyzed in [35] for MPPT applications, and based on the operating voltage range, power-handling capability, and output impedance of the solar array, the best topology was selected. Among these topologies, the conventional boost converter proved to be highly reliable due to its reduced device count. Nevertheless, the losses associated with the converter were high due to its reverse recovery diode. The switch-to-ground boost topology has a simple driving circuit and transfers energy directly from the input to the output. However, the topology has a high mass [35]. The topology was modified and proposed in [80] and is bidirectional with reduced mass and volume. The topology was specifically designed for high-power applications in LEO satellites. Another topology, the two-inductor boost topology proposed in [81], provides advantages like continuous input and output currents. However, the topology has two inductors and a poor dynamic response [35].  
The ripple cancellation-based boost converter proposed in [82] has an additional branch to cancel ripple in the input current. However, the number of components in the converter increases due to the additional branch added [35]. The common-damping two-inductor boost converter was derived from the two-inductor boost converter by adding a damping network, showing improved bandwidth and a complicated power structure. However, the converter leads to increased losses in the magnetic components [35]. Interleaving boost converters reduce the component count, provide a good transient response, and significantly reduce the output current ripple [83]. A boost-based multiple-input, multiple-output interleaved topology was proposed in [84] for spacecraft applications. The converter implements MPPT and provides a fixed voltage at the output and battery control. Figure 10 shows the various boost-derived topologies of DC-DC converters.  
Figure 10: Boost-derived topologies: (**a**) boost converter with a near switch ground, (**b**) 2-inductor boost converter, (**c**) ripple cancellation-based boost converter, (**d**) common damping 2-inductor boost converter, (**e**) interleaved boost converter, (**f**) 2-input multiple-output interleaved boost converter.  
Additionally, boost converters have also been proposed for battery discharge regulation in satellites, which regulate the bus voltage during eclipse periods. Ref. [85] proposed a family of 14 interleaved boost converters for BDRs in satellites. The converters demonstrated high efficiencies at output power ranging from 100 W to 1800 W. Due to the interleaved structure, all the converters showed good dynamic performance, no RHP zero effect, reduced filtering requirements, and low semiconductor device stresses. A similar application using a boost converter with an additional inductance was proposed in [86] for converting battery voltages between 55 V and 96 V to an average of 100 V output in satellites. An efficiency of about 97% was obtained with a reduced size. In general, boost converters have been mostly used for MPPT applications in small or large satellites, and their application as BDRs is also being studied.