This book focuses on the framework and implementation of energy integration systems with energy and smart-control technologies. It describes in detail We-Energy, a novel energy interaction mode based on a cyber-physical-economy-energy model, which can be adopted to solve the problem of energy supply and utilization. It then analyzes the key devices and technologies for developing the Energy Internet, such as converters, energy-conversion devices, system-level connection devices, optimization control strategies, cyber-physical system security, energy-system stability, communication technologies' operating modes and distributed optimization algorithms, to enable readers to gain a comprehensive understanding of the topic. Lastly, it offers an outlook on the development of the Energy Internet, providing a reference for cross-integration between different disciplines. The book is an indispensable resource for power enterprises, manufacturersin the power-supply industry, and researchers in the field of Energy Internet application. It is also useful for university and college teachers and students seeking to deepen their understanding of the Energy Internet, as well as for readers interested in the Energy Internet correlation techniques.