EE467-567'10_lect3-Fnl-3_1

# EE467-567'10_lect3-Fnl-3_1 - EE 467/567 INTEGRATED POWER...

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EE467/567 Integrated Power © 2010, D. C. Hopkins [email protected] EE 467/567 -- INTEGRATED POWER EE 467/567 -- INTEGRATED POWER ELECTRONICS ELECTRONICS Dr. Douglas C. Hopkins Dept. of Electrical Engineering University at Buffalo [email protected] EE467/567 Integrated Power © 2010, D. C. Hopkins [email protected] Digression into Digression into Gate Drivers and Miller Gate Drivers and Miller Capacitance Capacitance The electrical circuit include discrete and “parasitic” components. Current flow along a path encounters an inductance Voltages between two points encounter a capacitance NEED STUDENT TO DEVELOP THIS LECTURE MODULE

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EE467/567 Integrated Power © 2010, D. C. Hopkins [email protected] Rules for Sources Rules for Sources PT Krien Elements of Power Electronics Chapter 2 EE467/567 Integrated Power © 2010, D. C. Hopkins [email protected] V out V in I out I in Reality of Circuit Laws Reality of Circuit Laws KVL: ! v loop = 0 Unequal voltage sources cannot be interconnected. Attempts to connect unlike voltage sources yield extreme currents and failures. In the below circuit, the switch must be OFF so that KVL is not violated. KCL: ! i node = 0 Unequal current sources cannot be interconnected. Attempts to connect unlike voltage sources yield extreme currents and failures. In the below circuit, the switch must be ON, so that KCL is not violated .
EE467/567 Integrated Power © 2010, D. C. Hopkins [email protected] Energy storage is time-limited If we apply a continuous dc voltage to an inductor, then there is no time limitation on increasing current. An inductor should not have sustained dc voltage, unless “T” is limited! Implications for Storage Implications for Storage L V IN dt di L v L = i = 1 L v L dt + C 0 T "# \$ Energy storage is time-limited. If we apply a continuous dc current to a capacitor, then there is no time limitation on increasing voltage. A capacitor should not have sustained dc current , unless “T” is limited! I IN C i C = C dv dt v = 1 C i c dt + C 0 T "# \$ EE467/567 Integrated Power © 2010, D. C. Hopkins [email protected] Implications for Storage ( Implications for Storage ( con con ’d) The previous requirements imply that v L and i C must not have any dc component, i.e. the average : <v L > = 0, and <i C > = 0. These are key to circuit analysis: an inductor carries zero average voltage; a capacitor carries zero average current. We use these in “state equations” (which we will not learn about) to determine circuit operation. (Not all circuits have zero average - Pulse Circuits depend on a growing energy until the time of “firing” of the circuit. Think of the “Flash lamp” in a camera - the circuit voltage builds unbounded until the flash lamp bursts into light. Mother Nature’s lightning is a build up of charge in clouds until the withstand ability of the air is overcome, and a lightning bolt occurs.)

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EE467/567 Integrated Power © 2010, D. C. Hopkins
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EE467-567'10_lect3-Fnl-3_1 - EE 467/567 INTEGRATED POWER...

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