Singular Perturbation Theory-Based Qualitative Dynamics Investigation of Flywheel Energy Storage System in Discharge Mode

Table 1

Nomenclature for state variables.

State variables (with dimensions)	State variables (dimensionless)
Inductor current 𝑖𝐿	𝑋1(𝑖𝐿)
Load voltage 𝑢1	𝑋2(𝑢1)
Motor voltage 𝑢2	𝑋3(𝑢2)
Phase current 𝑖𝑎	𝑋4(𝑖𝑎)
Angular velocity 𝜔	𝑋5(𝜔)
Outer corrector output 𝑥1𝑐	𝑋6(𝑥1𝑐)
Inner corrector output 𝑥2𝑐	𝑋7(𝑥2𝑐)