Bài giảng Electrical and electronic principles: Chương 5 - ThS. Ngô Quốc Cường

Bài giảng Electrical and electronic principles - Chương 5 trình bày những nội dung chính sau: Magnetically coupled circuits, transformer, resonance. Mời các bạn cùng tham khảo để biết thêm các nội dung chi tiết.

TRƯỜNG ĐẠI HỌC SƯ PHẠM KỸ THUẬT TP HỒ CHÍ MINH ELECTRICAL AND ELECTRONIC PRINCIPLES WEEK Cuong Q Ngo Last classes • Maximum power transfer • MATLAB fundamentals • Single frequency AC analysis (MultiSim) CONTENTS (Today) • Magnetically coupled circuits • Transformer • Resonance 1.Magnetically coupled circuits • Mutual inductance – Mutual inductance is the ability of one inductor to induce a voltage across a neighboring inductor, measured in henrys (H) – If a current enters the dotted terminal of one coil, the reference polarity of the mutual voltage in the second coil is positive at the dotted terminal of the second coil 1.Magnetically coupled circuits • If a current leaves the dotted terminal of one coil, the reference polarity of the mutual voltage in the second coil is negative at the dotted terminal of the second coil • 1.Magnetically coupled circuits • Model 1.Magnetically coupled circuits • Example • Calculate the phasor currents I1 and I2 1.Magnetically coupled circuits • Answer I1  13.01  49.39 A I  2.9114.04 A Transformer Courtesy: Jensen Transformers Transformer • Ideal transformer – Coils have very large reactances – Coupling coefficient is equal to unity – Primary and secondary coils are lossless 10 Transformer • Typical circuits illustrating proper voltage polarities and current directions in an ideal transformer 11 Transformer • Input impedance • Complex power supplied by the source 12 Transformer • Example Find Vo and complex power supplied by the source 13 Transformer • Answer 14 Resonant circuits Series resonance • Resonance is a condition in an RLC circuit in which the capacitive and inductive reactances are equal in magnitude, thereby resulting in a purely resistive impedance • The value of 𝜔 that satisfies this condition is call resonant frequency 𝜔𝑜 15 Resonant circuits • Half-power frequencies • Relate the half-power frequencies with the resonant frequency • Bandwidth 16 Resonant circuits • Amplitude of current – At 𝜔 = 𝜔𝑜 – At 𝜔 = 𝜔1 17 Resonant circuits • The quality factor of a resonant circuit is the ratio of its resonant frequency to its bandwidth 18 Resonant circuits • Example • With R = Ω, L = mH, C = 0.4 àF Find the resonant frequency and half-power frequencies • Calculate the quality factor and bandwidth • Determine the amplitude of current at 𝜔𝑜 , 𝜔1 19 Resonant circuits • Answer • 50 krad/s; 25; krad/s; 10 A; 7.071 A 20 Resonant circuits Parallel resonance • Resonant frequency 21 Resonant circuits Parallel resonance • Half-power frequencies, bandwidth, and quality factor 22 ... frequency to its bandwidth 18 Resonant circuits • Example • With R = Ω, L = mH, C = 0.4 àF Find the resonant frequency and half-power frequencies • Calculate the quality factor and bandwidth • Determine... Answer • 50 krad/s; 25; krad/s; 10 A; 7.071 A 20 Resonant circuits Parallel resonance • Resonant frequency 21 Resonant circuits Parallel resonance • Half-power frequencies, bandwidth, and quality... condition is call resonant frequency