CP Signal with Optimized Frequency Function and Initial Phase

Lithium-ion batteries are increasingly used in electric vehicles and energy storage systems owing to their superior performance. Monitoring battery status is crucial for ensuring safe operation and prolonging the battery life. Electrochemical impedance spectroscopy (EIS) is a common method for studying the internal processes of batteries; however, traditional EIS methods require long measurement times, making them unsuitable for real-time applications. Researchers have proposed various broadband signals to reduce measurement time. Some researchers used different types of chirp signals as excitation signals, However, the pros and cons of existing types of chirp are not analyzed. In this letter, the characteristics of different chirps are compared with their drawbacks. Then, the relationship between the chirp rate and the amplitude-frequency characteristics of different chirps are analyzed. Based on the analysis, a new type of chirp with optimized frequency has been proposed, which ultimately overcomes the drawbacks of existing chirps. Finally, the effect of the initial phase on amplitude-frequency characteristics of the proposed cubic frequency chirp is investigated and find a relatively optimal initial phase.