EE155/255 Green Electronics

Transcription

1 EE155/255 Green Electronics Embedded Software Power Devices 10/2/17 Prof. William Dally Computer Systems Laboratory Stanford University

2 EE155/255 F17 L3 2 Lab group assignments Logistics Go to Canvas and group yourselves or we will group you Homework 1 due Today by 9am in box outside Sue s office Sign up for Lab signoff time Lab 1 must be signed off this week Sign up for Piazza piazza.com/stanford/fall2017/ee155ee255 Discussion sections Fridays 4:30-5:50PM STLC 118

3 Course at a Glance No Date Topic HW out HW in Lab out Lab ck Lab HW 1 9/25/17 Intro (basic converters) 1 1 Intro to ST32F3 Periodic Steady State 2 9/27/17 Embedded Prog/Power Elect. 3 10/2/17 Power Electronics - 1 (switches) AC Energy Meter Power Devices 4 10/4/17 Power Electronics - 2 (circuits) 5 10/9/17 Photovoltaics PV MPPT Motor control Matlab 6 10/11/17 Feedback Control 7 10/16/17 Electric Motors Motor control - Lab/ Feedback 8 10/18/17 Isolated Converters 9 10/23/17 Solar Day 5/PP PS Isolated Converters 10 10/25/17 Magnetics 11 10/30/17 Soft Switching 6 5/PP 6 5 Magnetics Magnetics and Inverters 12 11/1/17 Project Discussions 13 11/6/17 Inverters, Grid, PF, and Batteries 6 P 6 Project 14 11/8/17 Thermal & EMI 15 11/13/17 Quiz Review C /15/17 Grounding, and Debugging Q 11/15/17 Quiz - in the evening 11/20/17 Thanksgiving Break C2 11/22/17 Thanksgiving Break 17 11/27/17 Wrapup 18 11/29/17 Guest Lecture C /4/17 Guest Lecture 20 12/6/17 No Class TBD Project presentations P 12/15/17 Project webpage due EE155/255 F17 L3 3

4 EE155/255 F17 L3 4 PSSA in One Slide Green energy systems are made from voltage converters PV systems, electric/hybrid cars, wind power, etc Power path + intelligent control Separate behavior into fast and slow Fast within switching cycle Slow f << f cy Within cycle solve for periodic steady state State variables the same at start and end of cycle. For slow transient response Write difference equations Buck/Boost Topologies b/a il V 2 (V) ip i tb t0 tb tcy ta ω =1e+06 ζ =0.2 f = 1.59e+05 Q = time (µs) I L (V) V a b L i L + - V 2 = V 1 D a V 2 V L i L a b V 1 = V 2 = D a + - V 1 V 2 ( 1 D b )

5 EE155/255 F17 L3 5 Real-time, Event driven Embedded Software in One Slide Timer schedules periodic events (make sure work is done before next event) I/O devices signal completion Integer and FP Arithmetic Scale your numbers, avoid divides Layered design UI avoid modes, label buttons, it should be obvious Control at different frequencies Monitoring and Housekeeping

6 EE155/255 F17 L3 6 Organization of Code Control User Input Display Monitoring Housekeeping

7 EE155/255 F17 L3 7 Layered Control: Example Battery Charger User Interface Battery V, I Input V Battery V, I Mode Status State Selection State Target Selection Current 3A Driver I PWM Control PWM to Buck

8 EE155/255 F17 L3 8 Layered Control: Example Battery Charger Battery V, I Input V User Interface 50ms (or foreground) Mode State Selection 50ms State Status Battery V, I Target Selection 1ms Current 3A Driver I PWM Control 10us FPGA 100ns - Comparator PWM to Buck

9 EE155/255 F17 L3 9 Mode selection Example Photovoltaic Controller Line test, Panel test, MPPT, etc Monitors Line (current, voltage, frequency, ) (anti-islanding) Internal operation (voltages, currents, temps) Panels (current, voltage) Maximum Power-Point Tracking Search algorithm for peak power point Inverter control Convert 400V DC to 240V AC in sync with line User interface Display status, serial output, network connections,

10 EE155/255 F17 L3 10 Power Electronics Part 1 Power Devices

11 EE155/255 F17 L3 11 Real Switches V R a b L i L C + V 2 inh inl V 1 V GH High-Side Gate Drive Low-Side Gate Drive G2 G1 M2 M1 X _ GND V GL

12 EE155/255 F17 L3 12 Real Switches Finite switching time Finite voltage blocking Non-zero on resistance Parasitic L and C Need gate-drive supplies V R a b L i L C + V 2 inh inl V 1 V GH High-Side Gate Drive Low-Side Gate Drive G2 G1 M2 M1 X V GL _ GND

13 Quick Summary in a Few Pictures EE155/255 F17 L3 13

14 50A 45A 40A 35A 30A DC I-V Characteristics of On Switches 60V FET IRLB3036 Diode and IGBT Resistive at high Current 400V Diode STTH20R04 Ix(m:1) Ix(h:2) Ix(i:C) I(Dd) 600V IGBT FGH40N60 25A 20A 15A 10A 5A FETs Characterized By R ON 600V FET FCB36N60 HV FET has high RON R ~ kv 2 0A 0.0V 0.1V 0.2V 0.3V 0.4V 0.5V 0.6V 0.7V 0.8V 0.9V 1.0V 1.1V 1.2V 1.3V 1.4V 1.5V 1.6V 1.7V 1.8V 1.9V 2.0V V(d) IGBT Like a Diode Little Current Until ~0.7V EE155/255 F17 L3 14

15 EE155/255 F17 L KW 9KW 8KW 7KW 6KW 5KW 4KW 3KW 2KW 1KW 0KW 550V 500V 450V 400V 350V 300V 250V 200V 150V 100V 50V 0V 550V 500V 450V 400V 350V 300V 250V 200V 150V 100V 50V Transient Response of FET and IGBT ix(i:c)*v(di) ix(h:2)*v(dm) 36µJ 92µJ 36µJ 428µJ Instantaneous Power V(dm) 600V FET FCB36N60 V(di) 0V 0ns 40ns 80ns 120ns 160ns 200ns 240ns 280ns 320ns Turn On 600V IGBT FGH40N60 Turn Off Ix(h:2) Ix(i:C) 20A 15A 10A 5A 0A 20A 15A 10A 5A 0A

16 Boost Configuration for Transient Test EE155/255 F17 L3 16

17 EE155/255 F17 L3 17 Diode Reverse Recovery i D (Amps) I 1 t rr t 1 t a Q rr t b t 3 t (sec) I RM t 2

18 EE155/255 F17 L3 18 Diode Reverse Recovery 180A 40A I(D1) I(D2) I(D3) I(D4) I(D5) I(D6) I(D7) I(D1) I(D2) I(D3) I(D4) 20A 90A 0A 0A -20A -90A -40A -180A -60A -270A -80A -360A -100A -120A -450A -140A -540A -160A -630A -180A -720A -200A 400V Diode STTH20R04 Medium Speed Diode Area under curve (Charge) is approximately constant Q RR -810A -220A 0ns 10ns 20ns 30ns 40ns 50ns 60ns 70ns 80ns 90ns 100ns 110ns 120ns 0ns 3ns 6ns 9ns 12ns 15ns 18ns 21ns 24ns 27ns 30ns

19 Power MOSFETs EE155/255 F17 L3 19

20 Power MOSFETs are your friends EE155/255 F17 L3 20

21 EE155/255 F17 L3 21 Fast switching time 10-50ns Low switching losses MOSFET Properties Low conduction losses at low voltages V 2 /R of 1-2MW e.g., at 20V R = 0.4mOhm (4mV drop at 10A) Typically better than IGBT up to ~400V Easily paralleled for lower R on, More I, or easier cooling Integral body diode in DMOS FET Avalanche breakdown can be used to snub overshoot

22 EE155/255 F17 L3 22 MOSFETs are Switches Gate Drain Source (a) Gate R on (b) Drain Source D body

23 EE155/255 F17 L3 23 How do they Work + + V DS V DS V GS I DS gate gate n n n n p p g I DS =0 g I DS s d s d g=0 g=1 (a) (b)

24 EE155/255 F17 L3 24 Power MOSFET (DMOS) Structure source channel gate source p+ n+ n+ p+ n- n+ drain

25 Gate Charge vs V GS V GS (V) Q G (nc) EE155/255 F17 L3 25

26 EE155/255 F17 L3 26 Parasitics drain L D C DG gate R G L G C GS C DS 600V 0.1W FET TO220 Package L S source Symbol Value Units Description C DS 200 pf Drain-source capacitance C DG 70 pf Drain-gate (Miller) capacitance C GS 3600 pf Gate-source capacitance Q G 86 nc Total gate turn-on charge Q GD 35 nc Gate-drain turn-on charge L S 7 nh Source inductance L D 3 nh Drain inductance L G 7 nh Gate inductance R G 1.5 Gate resistance

27 EE155/255 F17 L3 27 Parasitics drain gate R G L G C GS C DG L D L S C DS C DS CV 2 energy L D, L S I 2 L energy slows switching, overshoot, corrupts gate drive C DG slows turn on R G, L G slow device turn-on source

28 EE155/255 F17 L3 28

29 EE155/255 F17 L3 29 Typical MOSFETs GaN SiC Device 20V IRLB3036 IRFB4227 FCB36N60N EPC2010 C2M Units V DSmax V R on m Q G nc C oss pf I Dmax A I DM A E AS mj P max W V 2 /R MW V 2 /RQ G mv/s

30 Power MOSFETs should be ON or OFF EE155/255 F17 L3 30 They are not happy in between IRLB3036 Can handle 60V (when its off) Can handle 195A (when its on if you can cool it) I 2 R = (195) 2 (0.002) = 76W But it can t handle 60V and 195A at the same time P = VI = (60)(195) = 11.7kW At least not for very long Turn them on and off quickly Best circuits are soft switching Zero-current switching (ZCS) or zero-voltage switching( ZVS) or both.

31 Power Diodes EE155/255 F17 L3 31

32 EE155/255 F17 L3 32 Self-controlling switch Diode Properties Allows current in one direction Turns off when current reaches zero (in theory) Relatively fixed voltage drop independent of current 0.5 to 2.0V High losses at low voltages Care required to operate in parallel Current hogging Turn-off delay Must clear space charge out of junction Turn-on delay Negligible for most fast diodes, but some are problematic

33 EE155/255 F17 L3 33 Reverse breakdown voltage Key Parameters Maximum current Reverse recovery time Junction capacitance

34 EE155/255 F17 L3 34 Diode Reverse Recovery i D (Amps) I 1 t rr t 1 t a Q rr t b t 3 t (sec) I RM t 2

35 EE155/255 F17 L3 35 Diode Forward Recovery v D (Volts) V FP 1.1V F V F t fr t (sec)

36 EE155/255 F17 L3 36 Diode Forward Recovery Good Diode Bad Diode

37 EE155/255 F17 L3 37 Two 2A Diodes < One 4A Diode C i D (Amps) C 25 C V (Volts) D

38 EE155/255 F17 L3 38 Summary Power Devices Finite, non-zero Drain Switching time Blocking voltage Gate R on D body drain On-voltage (resistance) Source L D Parasitics L and C gate R G L G C DG C DS MOSFETs switches C GS Turn on/off as fast as gate can be charged i D (Amps) L S source R = kv 2 Diodes Self-controlled switches I 1 t 1 t rr t a Q rr t b t 3 t (sec) I RM Reverse recovery loss Q RR t 2

39 Power Circuits EE155/255 Lecture 3 - Power Devices

40 EE155/255 Lecture 3 - Power Devices Practical Buck Converter inh High-Side Gate Drive G2 M2 V 1 V GH X inl Low-Side Gate Drive G1 M1 GND V GL

41 EE155/255 Lecture 3 - Power Devices Simple Model V G2 M2 i G1 M1

42 EE155/255 Lecture 3 - Power Devices One Switch May be a Diode Lower switch for buck G2 M2 Upper switch for boost V i Other switch does most of the work G1 M1 Synchronous rectification may be used to reduce loss

43 EE155/255 Lecture 3 - Power Devices Turn-On Loss I P I D I L Q RR Q D s V DS t 1 t 2 t 3

44 EE155/255 Lecture 3 - Power Devices Turn-On Buck w/ Diode I D I P I L Q RR Q D s t 1 ramp current to I L t 2 diode reverse recovery t 3 discharge drain capacitance V DS Current waveform in t 2 and t 3 may vary t 1 t 2 t 3

45 EE155/255 Lecture 3 - Power Devices Turn-On Buck w/ Diode I D V DS I P I L Q RR Q D s t 1 = I L s E 1 = 0.5V DD I L t 1 = 0.5V DDI L 2 t 2 = 2Q RR s E 2 = V DD t 2 s I L + 0.5t 2 s ( ) t 1 t 2 t 3 t 3 2I P Q D T3 is upside down T3 = 2Qd/Ip E 3 = 0.5V DD Q D V DD I L t 3

46 EE155/255 Lecture 3 - Power Devices Turn-Off Buck with Diode I L I D I 1 Excess current charges drain node. Integrate to get switching energy V DS t r t c! 1 E = V DD t r 6 I L I $ # 1& " %

47 EE155/255 Lecture 3 - Power Devices Turn-Off Buck with Diode I D I L If current ramps faster than voltage nearly ZVS t c E = 1 6 V 1I L t c V DS V 1 t r

48 EE155/255 Lecture 3 - Power Devices Parasitic Losses L P C L M 1 C 1 L 1 D 1 C 2

49 Switching Loss with SPICE EE155/255 Lecture 3 - Power Devices

50 EE155/255 Lecture 3 - Power Devices Boost configuration 40A, 50V IRLB V, 2mW FET Simulation Setup

51 EE155/255 Lecture 3 - Power Devices Ideal Diode, No Parasitics 22uJ turn-on 22uJ turn-off

52 EE155/255 Lecture 3 - Power Devices Body Diode of IRLB uJ turn-on 700A peak current

53 Gate Drive EE155/255 Lecture 3 - Power Devices

54 EE155/255 Lecture 3 - Power Devices Gate Driver drain S H R GH in V GH + - Control & Protection Gate-driver IC S L R GL M 1 source

55 EE155/255 Lecture 3 - Power Devices Effect of Miller Cap on Rise Time C DG M1 i G

56 EE155/255 Lecture 3 - Power Devices Effect of Miller Cap on Rise Time dv D dt = i G C DG C DG M1 Δt = ΔV DC DG i G i G Example: i = 0.5A, C = 100pF, DV = 400V

57 EE155/255 Lecture 3 - Power Devices Bootstrap Supply R B D B V inh C B High-Side Gate Drive G2 M2 V X i inl Low-Side Gate Drive G1 M1 GND V GL + -

58 Dead Time EE155/255 Lecture 3 - Power Devices

59 EE155/255 Lecture 3 - Power Devices Too Little Dead Time (11.6kW loss) 110KW ix(1:h:1)*(v(d)-v(m1)) ix(1:l:1)*v(m1) 100KW 90KW 80KW 70KW 60KW 50KW 40KW 30KW 4mJ 3.4mJ 3.7mJ 3.4mJ 20KW 10KW 0KW -10KW 3.0KA 2.5KA 2.0KA 2500A Ix(1:h:1) Ix(1:l:3) 1.5KA 1.0KA 0.5KA 0.0KA -0.5KA -1.0KA -1.5KA -2.0KA -2.5KA -3.0KA 16V V(p1l) v(p1h)-v(m1) V(1:gl) V(1:gh)-v(m1) 14V 12V 10V 8V 6V 4V 2V 0V 50V V(m1) 45V 40V 35V 30V 25V 20V 15V 10V 5V 0V -5V 1.6µs 1.7µs 1.8µs 1.9µs 2.0µs 2.1µs 2.2µs 2.3µs 2.4µs 2.5µs 2.6µs 2.7µs 2.8µs 2.9µs 3.0µs 3.1µs 3.2µs

60 v G (V) The Real Gate Signal v X (V) i M1 (ka) P M1 (kw) t (µ s) EE155/255 Lecture 3 - Power Devices

61 40KW 36KW Too Much Dead-Time (340W loss) ix(2:h:1)*(v(d)-v(m2)) (Still pretty good) ix(2:l:1)*v(m2) 32KW 28KW 24KW 20KW 16KW 12KW 8KW 0.27mJ 4KW 0KW -4KW 800A 700A 600A 500A 400A 300A 200A 100A 0A -100A -200A -300A -400A -500A -600A -700A 16V Ix(2:h:1) Ix(2:l:3) 740A V(p2l) V(p2h)-v(m2) V(2:gl) V(2:gh)-v(m2) 14V 12V 10V 8V 6V 4V 2V 0V -2V 50V V(m2) 45V 40V 35V 30V 25V 20V 15V 10V 5V 0V -5V 1.6µs 1.7µs 1.8µs 1.9µs 2.0µs 2.1µs 2.2µs 2.3µs 2.4µs 2.5µs 2.6µs 2.7µs 2.8µs 2.9µs 3.0µs 3.1µs 3.2µs 700mV diode drop EE155/255 Lecture 3 - Power Devices

62 2.7KW Just Right (310W loss) IX(4:l:1)*v(m4) ix(4:h:1)*(v(d)-v(m1)) 2.4KW 2.1KW 1.8KW 1.5KW 1.2KW 0.9KW 0.6KW 3uJ 0.19mJ 0.3KW 0.0KW -0.3KW 420A 350A 280A 210A 140A 70A 0A -70A -140A -210A -280A Ix(4:h:1) Ix(4:l:3) -350A 16V V(p4l) v(p4h)-v(m4) v(4:gh)-v(m4) V(4:gl) 14V 12V 10V 8V Slower gate rise 6V 4V 2V 0V -2V 50V V(m4) 45V 40V 35V 30V 25V 20V 15V 10V 5V Short duration diode drop 0V -5V 1.6µs 1.7µs 1.8µs 1.9µs 2.0µs 2.1µs 2.2µs 2.3µs 2.4µs 2.5µs 2.6µs 2.7µs 2.8µs 2.9µs 3.0µs 3.1µs 3.2µs Conduction loss is I 2 R = 50 2 x 1m ~ 25W EE155/255 Lecture 3 - Power Devices

63 Too much dead time is better than too little EE155/255 Lecture 3 - Power Devices

64 Snubbers EE155/255 Lecture 3 - Power Devices

65 EE155/255 Lecture 3 - Power Devices Dampen Ringing Nodes 40A C j D L D and C j resonate when M is on Parallel RS dampens tank L D R S Series C S limits dissipation G M C S V

66 EE155/255 Lecture 3 - Power Devices Inductance on Drain 42uJ turn-off 8uJ turn-on

67 EE155/255 Lecture 3 - Power Devices With Snubber (1nF, 5W) 2uJ in snubber 8uJ turn-on 42uJ turn-off

68 EE155/255 Lecture 3 - Power Devices Design Procedure C j Pick R S ~ 1/wC j 40A D Pick C S so t >= p/w Or E s = C S V 2 /2 L D R S G M C S V

69 EE155/255 Lecture 3 - Power Devices Move Turn-Off Dissipation to Passive Device 40A D R S D S G M C S V C S slows rise time of drain C S V 2 /2R S dissipated in R S when C S discharges Rarely used today Other forms slow fall time and rising/falling current

70 Summary Real switches have limitations Conduction losses (R ON for FETs, V CE for IGBTs, Diode drop) Switching losses (finite t on, t off, t rr ) With current source load, current ramps, then voltage falls And voltage rises before current falls May be dominated by reverse recovery time Complicated by inductance Power MOSFETs Switch quickly, have linear I-V, integral diode IGBTs Diode-like I-V, slower switching Diodes Have reverse recovery time Switches operate in pairs For one-way converters, one switch may be a diode Synchronous rectification make both switches FETs to reduce loss Need dead time to avoid shoot through current Gate-drive circuits control rise and fall times Bootstrap supply needed for high-side driver Snubbers dampen voltage and current transients

71 Course at a Glance No Date Topic HW out HW in Lab out Lab ck Lab HW 1 9/25/17 Intro (basic converters) 1 1 Intro to ST32F3 Periodic Steady State 2 9/27/17 Embedded Prog/Power Elect. 3 10/2/17 Power Electronics - 1 (switches) AC Energy Meter Power Devices 4 10/4/17 Power Electronics - 2 (circuits) 5 10/9/17 Photovoltaics PV MPPT Motor control Matlab 6 10/11/17 Feedback Control 7 10/16/17 Electric Motors Motor control - Lab/ Feedback 8 10/18/17 Isolated Converters 9 10/23/17 Solar Day 5/PP PS Isolated Converters 10 10/25/17 Magnetics 11 10/30/17 Soft Switching 6 5/PP 6 5 Magnetics Magnetics and Inverters 12 11/1/17 Project Discussions 13 11/6/17 Inverters, Grid, PF, and Batteries 6 P 6 Project 14 11/8/17 Thermal & EMI 15 11/13/17 Quiz Review C /15/17 Grounding, and Debugging Q 11/15/17 Quiz - in the evening 11/20/17 Thanksgiving Break C2 11/22/17 Thanksgiving Break 17 11/27/17 Wrapup 18 11/29/17 Guest Lecture C /4/17 Guest Lecture 20 12/6/17 No Class TBD Project presentations P 12/15/17 Project webpage due EE155/255 F17 L3 71