Lecture 1 Introduction & Basic Switching. Electric Drives Control 2

Transcription

1 1 Power Electronics

2 Lecture 1 Introduction & Basic Switching Electric Drives Control 2

3 We want torque! We are mainly interested in the mechanical torque on the electrical machine shaft But, the torque is the result of a complex interaction of electric voltages and currents, magnetic fluxes and mechanical layout Our source is (usually) a DC Voltage, that... we convert to AC with PWM and feed to the electrical machine to... control the machine currents such that the mechanical torque becomes the one we want. Against us we have: A machine that require voltages that increase with speed A battery with limited and almost constant voltage A converter that needs to be controlled in a microsecond time scale Electric Drives Control 3

4 How we do it? We start knowing: The desired torque Lots of system states, like speed, DC link voltage, phase currents, battery SOC,... We calculate: The traction machine currents needed The voltages needed to set these currents The modulation pattern needed to set these voltages We modulate the swithes accordingly! Torque Ref Torque control Current refs Voltage refs Switch states Output Voltage Current Control Modulation This course DC Link Voltage feedback PEC Current, Speed and Position feedback Electric Drives Control 4

5 Why Power Electronics? The efficiency of a linear amplifier (converter) has a theoretical upper limit of 78.5 % This is sufficient in many low power applications, such as home audio In trains the rated power may be as high as 4-8 MW For an efficiency of 78.5 % the losses would be MW This means that huge amounts of power and money would be lost... but the main problem would be thermal management, i.e. handling the heat power Typically, the efficiency of a power electronic switch mode converter is >98 %

6 Simple low power amplifiers A B och AB Eff = 20 25% Eff = 60 % Electric Drives Control 6

7 Class D Audio Amplifiers

8 What is Power Electronics used for? All kinds of electrical drives where electrical power is transfered to mechanical and variable speed is required such as Traction applications such as trains, electrical vehicles and ship propulsion Pumps and fans All kinds of electrical drives where electrical power is transfered to mechanical and position control (servo) is required such as Robots, cranes Power system applications such as HVDC (up to 3000 MW), Transistor based HVDC Feeding and priming power from renewable energy sources (solar, wind,...) Active power filters, reactive power compensation,... Power supplies Computers, tv-sets,... Battery chargers for computers, mobile phones, hand-held tools,... - Back-up power, i.e. uninteruptable power supplies Many other applications

9 Electrical Motor Drives

10 Typical Motor Drive Applications - Except pumps, fans, cranes, Traction: for example trains and hybrid vehicles Robotics Series Hybrid Prallel Hybrid Series-Parallel Hybrid

11 Energy Conversion in Hybrid Vehicles Electric Drives Control 11

12 Torque Volvo s main system Diesel engine Electric motor 70 kw cont, 120 kw peak 400 Nm cont, 800 Nm peak AMT gearbox Energy storage 600 VDC Both Speed

13 Potential Fuel Saving Refuse Truck 20 % 5 % Long Haul Truck City Bus Wheel loader % %

14 Electric Drive is Good! Electric Traction Motors Are at least twice as energy efficiency as combustion engines Need almost no service, no sparkplugs, no oil changes.. Are quiet Let out no exhaust Are much smaller than a combustion engine for the same rating Can recover energy when slowing down or going downhill

15 But Storing Energy is a double problem... Time to charge 250 km Battery to store 250 km 5 minutes 150 kg diesel-tank 7 days 2500 kg battery 9 hours 2500 kg battery 4 hours 2500 kg battery

16 The Energy Path

17 Who needs an Automatic Charging Connection...? Commercial Vehicles May be Opportunity Charged up to times a day The power level is high! Automatic connection absolutely necessary!!! Autonomous private (?) vehicles Maybe a Spotify/Netflix/Uber kind of vehicle Must be able to autonomously arrange washing, charging, workshop visit,... Usually connected times per Future Charging Concepts day

18 The reinvented trolley reduce the need for batteries AND is automatic! Future Charging Concepts

19 Elonroad Elways -90 % battery size! Alstom/Volvo Future Charging Concepts

20 Vision Future Charging Concepts

21 Societal value... 4x ERS cost If ALL cars in Sweden were a Tesla : 472 meter 2 million m 3 batteries If ALL HDT were equipped fo 4h full electric mode 325 meter 0.2 millioner m 3 batteries IF we stack these as a cone...? With the same base as the Eiffel-tower...? m 47 meter 125 m Future Charging Concepts

22 Alternatives OFF Board High Power Charger High cost off board (currently 7 k /kw, excl installation) Low cost on board Robotic connector included ON Board High Power Charger Low cost off board (<< 1k /kw, excluding installation) Moderate cost On Board (Renault 150 for 43 kw by integration!!!) Robotic Connector To Be Developed

23 Renault Traction System Renault logic: Energy Infrastructure MUST be dense. DC connection for high power charging NOT the right way to go grid voltage, NOT battery voltage. Low Cost High Power AC infrastructure needed, with On Board Charger The Power level will increase Today 43 kw, tomorrow >80 kw Robotized Connection necessary

24 Frequency Conversion Japan East / West 50/60 Hz 600 MW

25 HVDC Japan: Hokkaido to Honshu / 600 MW

26 HVDC and Transistor Based HVDC

27 Camera with flash

28 Audio amplifiers Electric Drives Control 32

29 Renewable Energy Systems Converters Suitable for Solar Cells Without transformer With transformer

30 i Line i AF Active Filters i Load i Line [A] i Load i AF I h [A rms ] Load Line AF t [ms] h V 50 Hz L 2 L 1 C V dc C dc V batt Line side filter Line side converter DC link Battery side converter Battery side filter

31 Switch Mode Power Supplies - Forward Converter

32 Thank You!

33 The Course 2017 Lectures 2 times a week 2 3 exercises a week 6 labs with home assignments / simulation exercises: The Flyback Converter The H-bridge Speed Control with a DC Machine Control of an Active Power Filter Control of PM Machines Control of Induction Machines

34 Teaching Plan Week Who Date Time Lecture Content Who Date Time Lecture Content Who Date Time Lecture content Lab w ho 3 Mats Intro + Diode/Thyristor & Rectifier Hans Buck converter, sw itch, snubbers Hans Lab Flyback converter preparation Philip 4 Mats DC/DC conv +1 phase modulation Mats H-bridge + 2 phase modulation Mats Lab H-bridge preparation Philip 5 Hans DC Current Control Hans Position and Speed Control Hans Torque Generation Lab Flyback 6 Mats DC-machine theory Mats DC Machine Control Mats Lab DC-machine preparation Lab H-bridge Samuel/Max 7 Mats AC-pow er + 3 phase modulation Hans AC Current Control Hans Lab Active filter preparation Samuel/Max 8 Hans Pow er Systems Applications Hans Synchronous Machine and PMSM Mats Lab DC 9 Mats Control of PMSM Hans Induction Machine Modelling Hans Lab AF Samuel/Max Mats Control of Induction Machine Mats/Samuel? Self studies Exam w eek Lab PMSM preparation 13 Hans Semiconductor PN junction Hans Semiconductor Mos IGBT 14 Mats New materials, Silicon Carbide Mats / Gabriel? Lab Induction Machine preparation Lab PMSM Easter w eek Re-exam w eek? 17 Hans Passive components (Ind&Cap) Mats Losses, Temp, cooling 18 Hans Resonance and Multilevel converter Hans Guest Lecture - ESS (Carlos?) Lab IM 19 Hans EMC Hans Guest Lecture - ERS (Dan Z, Lars L?) 20 Mats Guest Lecture - Hybrid Mats Guest Lecture - ERS 21 Self studies 22 Mats Tentamen

35 Home Assignments Content as similar as possible to the labs Prepares you for the lab Diagnostic tests can be used before the labs You must pass!

36 Teachers Lectures: Mats Alaküla, professor, Senior Scientific Advisor Volvo Powertrain Hans Bängtsson, professor, Adjunct Professor Lund University, former Senior Specialist Power Electronics and EMC at Bombardier Course assistance, simulation exercises and Labs: Max Collins, PhD student Samuel Estenlund, PhD Student

37 Components

38 Components 1 : The transistor Works like a valve for electric current Compare to a water tap Control a big flow with a small movement Flow x Pressure drop = Power Heats the water (a little) A transistor Controls a big current with a small current The voltage drop across the transistor x the current = Power Heats the transistor (a lot)

39 Components 2: The Diode i Anod i + u Ledtillstånd Katod - Spärrtillstånd u Backriktning Framriktning

40 Components 3: The IGBT transistor i C Bottnad Kollektor Gate + u GE - Emitter i C + u CE - Symbol Strypt u GE3 u GE2 u GE1 Ökande u GE Effektgräns u CE

41 Components 4: The Capacitor Stores electric current with increasing voltage like a hydrophore stores a fluid or gas with increasing pressure du c dt i c + uc - 1 i C

42 Components 5: The Inductor Stores currrent into magnetic energy like a flywheel stores torque into speed and mechanical energy di dt L 1 L u L i L + u L -

43 Never break an inductive current Never short a capacitive voltage u c i c i L u L du dt c 1 C i c di dt L 1 L u L

44 Basic Switching

45 Fundamentals of Switching U 0 I a U t Analogue P load = U load *I a P loss = U t *I a U t U load P loss P load 0 U load Switched On Off U t 0 U t = U 0 I a = I load I s = 0 P loss = 0 P loss = 0 I a t t Electric Drives Control 49

46 Never break an inductive current Never short a capacitive voltage Electric Drives Control 50

47 BASIC turn on current step, capacitive load. No problem i I du dt i C u u,i t Electric Drives Control 51

48 BASIC turn off current step, capacitive load. No problem i I u,i u du dt i C t Electric Drives Control 52

49 BASIC turn on voltage step with capacitive load. Problem! i i C du dt + U - u u,i t U u Electric Drives Control 53

50 BASIC turn off voltage step, capacitive load. No problem i i C du dt + U - + u - u,i U u t Electric Drives Control 54

51 BASIC voltage ramp, capacitive load. No problem + U - i i C du dt u,i t Electric Drives Control 55

52 BASIC turn on current step, inductive load. Problem i u di L dt u,i I + u - t I > i Electric Drives Control 56

53 BASIC turn on current step, inductive load. Counter measure with capacitor i u di L dt I + u - u,i t I > i Electric Drives Control 57

54 BASIC turn off current step, inductive load. Problem i u di L dt u,i I + u - t Electric Drives Control 58

55 BASIC turn off current step, inductive load. Counter measure with freewheeling diode i u,i I + u - t Electric Drives Control 59

56 BASIC current ramp, inductive load. No problem i u L di dt I + u - u,i t Electric Drives Control 60

57 BASIC turn on voltage step with inductive load. No problem i u,i U U u u L di dt t Electric Drives Control 61

58 BASIC turn off voltage step, inductive load No problem i du i C dt + U - + u - u,i t Electric Drives Control 62

59 Summary An inductance keeps a current constant u di dt u L i Electric Drives Control 63

60 Summary A capacitance keeps a voltage constant du dt i C i u Electric Drives Control 64

61 Single phase diode rectifier ideal

62 Single phase diode rectifier ideal Positive U0 1 0,5 0-0, ,5 0-0, Negaative

63 Single phase diode rectifier voltage 1 0,5 0-0, T/2 V dc 1 T 2 T eˆ LN 2 cos( t) dt eˆ LN cos( t) d( t) eˆ LN 2 2 E LN Line-to-neutral voltage and DC side voltage for a singlephase diode rectifier

64 Quadrants i i i i u u u u 1-quadrant 2-quadrant 2-quadrant 4-quadrant Power Electronic Converter i + u - Electric Drives Control 68

65 Classification Inversion DC-voltage conversion DC Voltage AC voltage AC voltage conversion Rectification Electric Drives Control 69

66 Some fundamental topologies

67 The Buck Converter (Step-Down Converter) Figure 1.16: Buck converter. S on V dc V load v L di L dt L i L V dc V L load DT sw S off dil V V load load vl L il 1 D dt L T sw Figure 1.17: Ideal waveforms of the Buck converter.

68 The Boost Converter (Step-Up Converter) Figure 1.18: Boost converter. S on di L dt L v L V in v S V in i L V L in DT sw S off di L dt L v L V in v D V out V in V out Vin Vout il 1 D L T sw Figure 1.17: Ideal waveforms of the Boost converter. Replace V dc and V load of the Buck converter with V out and V in

69 The Buck-Boost Converter (Half-Bridge) Figure 1.19: Buck-boost converter. S on V dc V load v L di L dt L i L V dc V L load DT sw S off dil V V load load vl L il 1 D dt L T sw Figure 1.17: Ideal waveforms of the Buck-boost converter.

70 General SMPS Figure 1.20: Principal schematic of a switch-mode power supply.

71 The Flyback Converter Figure 1.23: Principal schematic of a flyback converter. Only the devices needed to understand the operation are included.

72 The Laboratory Flyback Converter Flyback converter with input filter, inrush current limitation, diode rectifier, dc link capacitors, power MOSFET, transformer, output filter and three snubber circuits. The controller circuits are not included in the circuit.

73 Diode rectifier with capacitive DC link Figure 1.1: A single-phase diode rectifier with a capacitive DC link. Figure 1.2: Line-to-neutral voltage and DC side voltage for a single-phase diode rectifier with a capacitive DC link. V dc 1 T 2 T eˆ LN 2 eˆ LN cos( t) dt cos( t) d( t) eˆ 2 LN 2 2 E LN Figure 1.3: Line current (left) and its frequency spectrum (right), for a single-phase diode rectifier with a capacitive DC link.

74 That s all folks... Electric Drives Control 78