Experiment on Inverter System - Renewable and Power Electronics Lab | ECEN 4517, Study notes of Electrical and Electronics Engineering

Download Experiment on Inverter System - Renewable and Power Electronics Lab | ECEN 4517 and more Study notes Electrical and Electronics Engineering in PDF only on Docsity! ECEN 4517 1 Lecture 8 ECEN 4517/5517 Step-up dc-dc converter with isolation (flyback) Feedback controller to regulate HVDC Experiment 4: inverter system DC-AC inverter (H-bridge) 12 VDC HVDC: 120 - 200 VDC AC load 120 Vrms 60 Hz Battery DC-AC inverter H-bridge DC-DC converter Isolated flyback +– d(t) Feedback controller Vref Digital controller d(t) + vac(t) – ECEN 4517 2 Due dates Right now: Prelab assignment for Exp. 4 Part 2 (one from every student) Due within five minutes of beginning of lecture This week in lab (March 4-6): Experiment 3 report due (one per group). Next week in lecture (March 11): Preliminary project proposal due (one from every group) The following week in lecture (March 18): Midterm examination ECEN 4517 5 PWM Inverter Average vac(t) has a sinusoidal waveform Inverter transistors switch at frequency substantially higher than 60 Hz • Choose VHVDC larger than desired Vac,peak • Can regulate waveshape and value of Vac,RMS by variation of d(t) • Can achieve sinusoidal waveform, with negligible harmonics • Higher switching frequency leads to more switching loss and need to filter high-frequency switching harmonics and common- mode currents t vac(t) ECEN 4517 6 The IR3101 half-bridge module Module contains power MOSFET and diodes, gate drivers, bootstrap power supply • MOSFET ratings 450 V, 1.8 A • Use VCC = 12 V • Connect 100 μF 25 V bootstrap capacitor between VB and Vo • Logic signals Hin and Lin control upper and lower MOSFET drivers. These signals must not both be high at the same time! Need deadtime of at least 200 nsec. ECEN 4517 7 Controlling the inverter MSP430 generates logic signals to control the four gate drivers • Control MSP430 Timer B IR3101 IR3101 vHVDC AC load 120 Vrms 60 Hz + vac(t) – MSP430 iac(t) 12V 12V P4.1 to P4.4 P6.0Vref to flyback controller DAC1 Timer B Q1 Q2 Q3 Q4 Your goal: adjust Vref and inverter duty cycle to obtain Vac = 120 V rms DC/DC converter (peak power tracker) Vb Io + _ Vg Feedback controller Ig Vg Voc Isc Battery Solar panel Q peak power point IgQ VgQ 12-15V DC 200V DC DC/AC inverter vo(t) Feedback controller + _ load 120Vrms 60Hz AC power flow DC/DC converter (step up) Feedback controller 120Vrms 60Hz Utility AC line or 3-phase wind-powered generator AC/DC low-harmonic rectifier single-phase or 3-phase Feedback controller Variable-speed DC drive Feedback controller DC motor Vm + _ 5-30V DC speed ω power flowpower flow High-frequency DC/AC resonant inverter (Fluorescent lamp ballast) Audio Switching Amplifier (DC/AC) Basic non-isolated converters + – Q1 L C R + V – D1Vg iL(t) iD(t) Buck converter • M(D) = D • Step-down • Requires floating gate drive + – Q1 L C R + v(t) – D1 Vg i(t) + vL(t) – iD(t) iC(t) Boost converter • M(D) = 1/(1 – D) • Step-up • Ground-referenced gate drive M(D) = V/Vg Basic non-isolated converters Buck-boost converter • M(D) = – D/(1 – D) • Step up or down • Inverting • Requires floating gate drive H-bridge converter • M(D) = 2D – 1 • Step-down • Bipolar output • Requires floating gate drives + – L C R + V – Vg Q1 D1 i(t) R + –Vg D1Q1 D2 Q2 D3Q3 D4 Q4 L C + V – More isolated converters Flyback converter • M(D) = nD/(1 – D) • Ground-referenced gate drive • Based on buck-boost Push-pull boost converter • M(D) = n/(1 – D) • Alternating gate drive; current mode control • Ground-referenced gate drive + – LM + V – Vg Q1 D11:n C +– Vg C R + V – L D1 D2 1 : n Q1 Q2 + vL(t) – – vT(t) + – vT(t) + io(t) i(t) More isolated converters Isolated SEPIC • M(D) = nD/(1 – D) • Ground-referenced gate drive • Based on SEPIC Isolated Cuk + – D1L1 C2 + v – Q1 C1 RVg 1 : n ip isi1 + – D1 L1 C2 R + v – Q1 C1a L2 Vg C1b 1 : n • M(D) = nD/(1 – D) • Ground-referenced gate drive • Based on Cuk Low harmonic rectifiers Can employ boost, flyback, SEPIC, Cuk, and other converters having boost capability, to control and regulate ac input current to follow ac voltage. Boost example: • Controller varies d(t) such that ig(t) = vg(t)/Re • Re = emulated resistance Boost converter Controller Rvac(t) iac(t) + vg(t) – ig(t) ig(t)vg(t) + v(t) – i(t) Q1 L C D1 d(t) Controller approaches: • Average current control • Critical conduction mode control • Current mode control • Discontinuous conduction mode