Exercise 3.1 Figure 29: Rotor position of Exercise 3.1. Note that the north pole is on top at angle zero position. 1. Which switches (S1-Se) in Fig.29 are conducting when the rotor is at the given position? Assume rotor is accelerating in CCW direction. Explain. 2. Find and sketch the induced voltages and phase currents of three-phase ECM for one rotation in terms of 8, when the machine is operating at a speed of 1800rpm and the load torque is INm in steady-state. Motor parameters are as follows: number of turns in each phase is 100, magnetic flux density from the rotor permanent magnet is 0.17, rotor length is 0.1m, and rotor radius is 0.25m. SAM (a) (b) (c) (d) Figure 30: Torque generation with concentrated windings. (a) Stator with windings (inside) and rotor with permanent magnet (outside), (b) 8 = 0, (c) 8 60, (d) 8 = 120. (Source: www.patreon.com/LearnEngineering) e 1 EN 2.1 1 1 Pec 1 1 2. 8 1 MP 1 1 Figure 31: Back-EMF of BLDC rotating in CW direction in Fig. 30 case. Note that the north pole is on top at angle zero position. Compare with Fig. 23b. Exercise 3.1 Figure 29: Rotor position of Exercise 3.1. Note that the north pole is on top at angle zero position. 1. Which switches (S1-Se) in Fig.29 are conducting when the rotor is at the given position? Assume rotor is accelerating in CCW direction. Explain. 2. Find and sketch the induced voltages and phase currents of three-phase ECM for one rotation in terms of 8, when the machine is operating at a speed of 1800rpm and the load torque is INm in steady-state. Motor parameters are as follows: number of turns in each phase is 100, magnetic flux density from the rotor permanent magnet is 0.17, rotor length is 0.1m, and rotor radius is 0.25m. SAM (a) (b) (c) (d) Figure 30: Torque generation with concentrated windings. (a) Stator with windings (inside) and rotor with permanent magnet (outside), (b) 8 = 0, (c) 8 60, (d) 8 = 120. (Source: www.patreon.com/LearnEngineering) e 1 EN 2.1 1 1 Pec 1 1 2. 8 1 MP 1 1 Figure 31: Back-EMF of BLDC rotating in CW direction in Fig. 30 case. Note that the north pole is on top at angle zero position. Compare with Fig. 23b