current and torque at l200 rpm. (16) Explain in detail, the v/f control of induction motor drives. (16) Explain in detail, the principle of operation and drive strategy of constant air gap flux control of induction motors. (8) A 3 phase, 56 kW, 4000 rpm, 460 V, 60 Hz, 2 pole star connected induction motor has the following parameters: Rs = 0, Rr = 0.28 Xs = 0.23 Xr = 0.23 and Ω, Ω, Ω Xm = 11 The motor is controlled by varying the supply frequency. If the break down Ω. torque requirement is 70 Nm. Calculate the supply frequency and the speed at the ωm maximum torque. (8) A 3 star connected, 60 Hz, 4 pole induction motor has the following parameters for the per phase equivalent circuit. Rs = Rr = 0.024 and Xs = Xr = 0.12 The motor is Ω Ω. controlled by the variable frequency control with a constant (v/f) ratio. For an operating frequency of 12 Hz, calculate the breakdown torque as a ratio of its value at the rated frequency for both motoring and braking. (8) Compare CSI drive with VSI drives. (8) Explain in detail, the vector control of Induction motor drives. (16) Explain in detail, the principle of operation of Scherbius system. (16) Explain in detail, the closed loop speed control of VSI fed and CSI fed induction motor drives. (16) UNIT 5 Part-A When is a synchronous motor said to be self-controlled? Why self-controlled synchronous motor is free from hunting operations? Define Self-control Technique of synchronous motor – Which type of control can be used for constant torque operation in synchronous motor? What are the different types of controls used in Synchronous motor drives? What are the characteristics of self-controlled mode operated synchronous motor?
current and torque at l200 rpm. (16) Explain in detail, the v/f control of induction motor drives. (16) Explain in detail, the principle of operation and drive strategy of constant air gap flux control of induction motors. (8) A 3 phase, 56 kW, 4000 rpm, 460 V, 60 Hz, 2 pole star connected induction motor has the following parameters: Rs = 0, Rr = 0.28 Ω, Xs = 0.23 Ω, Xr = 0.23 Ω and Xm = 11 Ω. The motor is controlled by varying the supply frequency. If the break down torque requirement is 70 Nm. Calculate the supply frequency and the speed ωm at the maximum torque. (8) A 3 star connected, 60 Hz, 4 pole induction motor has the following parameters for the per phase equivalent circuit. Rs = Rr = 0.024 Ω and Xs = Xr = 0.12 Ω. The motor is controlled by the variable frequency control with a constant (v/f) ratio. For an operating frequency of 12 Hz, calculate the breakdown torque as a ratio of its value at the rated frequency for both motoring and braking. (8) Compare CSI drive with VSI drives. (8) Explain in detail, the vector control of Induction motor drives. (16) Explain in detail, the principle of operation of Scherbius system. (16) Explain in detail, the closed loop speed control of VSI fed and CSI fed induction motor drives. (16) UNIT 5 Part-A When is a synchronous motor said to be self-controlled? Why self-controlled synchronous motor is free from hunting operations? Define – Self-control Technique of synchronous motor Which type of control can be used for constant torque operation in synchronous motor? What are the different types of controls used in Synchronous motor drives? What are the characteristics of self-controlled mode operated synchronous motor?
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