® ® Florin Lungeanu Power & Control Development Engineer, Danfoss Drives A/S Marian Lungeanu Hardware Development Engineer, Danfoss Drives A/S © 2008 The MathWorks, Inc. Temperature Estimation in Power Modules, via Power Loss Calculation ® What is a Variable Frequency Drive? ® part 1 www.wikipedia.org variable frequency equals variable shaft speed 2 ® ® What is a Variable Frequency Drive? part 2 www.wikipedia.org 3 x 400 V 50 Hz 1 x 560 V DC 3 x 0…400 V 0…1000 Hz 3 ® What is a Variable Frequency Drive? ® part 3 4 ® ® How does a VLT® Look Like? Danfoss Drives Standard Products Danfoss Drives Customised Products 5 ® ® What is a Power Module? Classic IGBT Power Module with: - three-phase passive rectifier; - three-phase inverter; - brake chopper; - temperature sensor. 6 ® Dynamic Simulation, Simulink / PLECS 700 In ® part1 Out is_abc w_ref is_abc PI control 0 pulses PLECS v bc Circuit Relay RRF->3ph Tm m Constant Circuit pi/2 Tm 4 v_bc Demux Gain1 4 we Gain2 Te Jost Allmeling, Plexim GmbH 7 ® Dynamic Simulation, Simulink / PLECS ® part2 8 ® ® Steady State Modelling - Conduction per unit The current flowing through semiconductors will generate heat via conduction loss. The switching of the current through semiconductors will also generate heat via switching loss. 9 ® ® Steady State Modelling - Switching 10 ® ® 50 TransCondLoss TransTotLoss DiodeCondLoss DiodeTotLoss 40 30 PLossAvgT = 11.397 [W] PLossAvgD = 1.2964 [W] PLossRecD = 3.1124 [W] PLossCondAvgT = 9.5931 [W] PLossCondAvgD = 0.96453 [W] 20 10 0 0 0.005 0.01 0.015 0.02 110 78 77 105 Tchs - igbt = 70 [ oC] TjcIgbt = 95 [oC] 100 Ths- igbt = 69 [oC] o maxTjcIgbt = 109 [ C] minTjcIgbt = 93 [oC] 76 Tchs -fwd = 70 [ oC] TjcFwd = 74 [ oC] Ths- fwd = 69 [oC] maxTjcFwd = 77 [ oC] 75 minTjcFwd = 74 [ oC] 95 90 0.025 74 73 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 11 ® ® The Idea make database with power modules and motors solve modulation/pulse patterns in steady state calculate on-time pulses distribute voltage and current for each switching period calculate power loss per switching cell integrate the thermal model in Simulink, import results show the results in GUI save the results in files 12 ® ® Switching Cell Concept, T+D i > 0, current through transistor i < 0, current through diode i > 0 & gate turns ON, switch ON event i > 0 & gate turns OFF, switch OFF event i < 0 & gate turns OFF, diode RR event 13 ® ® event Steady-State Inverter Model 14 ® ® Power Loss on Upper Cell, Phase U if (i PH < 0 ): PlD = v D ⋅ i PH + E RR ⋅ FSW if (i PH > 0 ): PlT = vT ⋅ i PH + (EON + EOFF ) ⋅ FSW Pcell = PlD + PlT Fsw – switching frequency E – switching energy 15 ® ® Total & Conduction Power Loss / Inverter 16 ® ® Solving Thermal Model in Simulink Foster thermal model, with four elements PtotFwd TjFwd Scope2 Repeating Sequence: PLossSwPerD Thermalmodel_Fwd Ptot Scope TjIgbt -CRepeating Sequence: PLossSwPerT Thermalmodel_Igbt Scope1 Scope3 Tc 17 ® ® Thermal Model & Temperature, T+D 18 ® ® 50 TransCondLoss TransTotLoss DiodeCondLoss DiodeTotLoss 40 30 PLossAvgT = 11.397 [W] PLossAvgD = 1.2964 [W] PLossRecD = 3.1124 [W] PLossCondAvgT = 9.5931 [W] PLossCondAvgD = 0.96453 [W] 20 10 0 0 0.005 0.01 0.015 0.02 110 78 77 105 Tchs - igbt = 70 [ oC] TjcIgbt = 95 [oC] 100 Ths- igbt = 69 [oC] o maxTjcIgbt = 109 [ C] minTjcIgbt = 93 [oC] 76 Tchs -fwd = 70 [ oC] TjcFwd = 74 [ oC] Ths- fwd = 69 [oC] maxTjcFwd = 77 [ oC] 75 minTjcFwd = 74 [ oC] 95 90 0.025 74 73 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 19 ® ® Conclusions Matlab is a superior tool for steady state analysis of electrical circuits in general, and power electronics involved in electrical drives in particular – compared to Spice/Saber like programs. The hardware, software, and control professionals can better handle the practical challenges in VFD with Matlab. Running the developed program outside Matlab environment will increase usability even further. Future dynamic analysis may be added to support and complement the actual steady-state results. 20