319828.fig.003a
(a)
319828.fig.003b
(b)
319828.fig.003c
(c)
319828.fig.003d
(d)
Figure 3: Experimental results of PI control system with mounted electric scooter at 1200 rpm: (a) command rotor speed 𝜔 , measure rotor speed 𝜔 𝑟 , and estimate rotor speed 𝜔 𝑟 ; (b) measure rotor position 𝜃 𝑟 and estimate rotor position ̂ 𝜃 𝑟 ; (c) command current 𝑖 𝑎 and measure current 𝑖 𝑎 in phase 𝑎 ; (d) command current 𝑖 𝑏 and measure current 𝑖 𝑏 in phase 𝑏 .