Power Semiconductors: Basic Operating Principles ..................................................... 1
1.1 Basics for the operation of power semiconductors ......................................................
1
1.2 Power electronic switches ............................................................................................ 5
2 Basics............................................................................................................................... 13
2.1 Application fields and current performance limits for power semiconductors.............. 13
2.2 Line rectifiers.............................................................................................................. 17
2.2.1 Rectifier diodes.................................................................................................... 17
2.2.1.1 General terms................................................................................................ 17
2.2.1.2 Structure and functional principle................................................................... 18
2.2.1.3 Static behaviour............................................................................................. 20
2.2.1.4 Dynamic behaviour........................................................................................ 20
2.2.2 Thyristors............................................................................................................. 22
2.2.2.1 General terms................................................................................................ 22
2.2.2.2 Structure and functional principle................................................................... 23
2.2.2.3 Static behaviour............................................................................................. 25
2.2.2.4 Dynamic behaviour........................................................................................ 26
2.3 Freewheeling and snubber diodes ............................................................................. 28
2.3.1 Structure and functional principle ........................................................................ 28
2.3.1.1 Schottky diodes ............................................................................................. 29
2.3.1.2 PIN diodes ..................................................................................................... 30
2.3.2 Static behaviour .................................................................................................. 32
2.3.2.1 On-state behaviour ........................................................................................ 32
2.3.2.2 Blocking behaviour ........................................................................................ 33
2.3.3 Dynamic behaviour.............................................................................................. 34
2.3.3.1 Turn-on behaviour ......................................................................................... 34
2.3.3.2 Turn-off behaviour.......................................................................................... 35
2.3.3.3 Dynamic ruggedness ..................................................................................... 43
2.4 Power MOSFET and IGBT ........................................................................................ 43
2.4.1 Structure and functional principle ........................................................................ 43
2.4.2 IGBT.................................................................................................................... 46
2.4.2.1 Static behaviour............................................................................................. 48
2.4.2.2 Switching behaviour....................................................................................... 49
2.4.2.3 IGBT – Concepts and new directions of development ................................... 54
2.4.3 Power MOSFET................................................................................................... 61
2.4.3.1 Static behaviour............................................................................................. 63
2.4.3.2 Switching behaviour....................................................................................... 66
2.4.3.3 Latest versions and new directions of development....................................... 69
2.5 Packaging .................................................................................................................. 72
2.5.1 Technologies ....................................................................................................... 73
2.5.1.1 Soldering ...................................................................................................... 73
2.5.1.2 Diffusion sintering (low-temperature joining technology)................................ 73
2.5.1.3 Wire bonding ................................................................................................. 75
2.5.1.4 Pressure contact............................................................................................ 75
2.5.1.5 Assembly and connection technology............................................................ 76
2.5.1.6 Modules with or without base plate ............................................................... 78
2.5.2 Functions and features ........................................................................................ 80
2.5.2.1 Insulation ...................................................................................................... 80
2.5.2.2 Heat dissipation and thermal resistance ........................................................ 82
2.5.2.3 Power cycling capability................................................................................. 91
2.5.2.4 Current conduction to the main terminals ...................................................... 91
2.5.2.5 Low-inductance internal structure .................................................................. 92
2.5.2.6 Coupling capacitances................................................................................... 93
2.5.2.7 Circuit complexity........................................................................................... 94
II
2.5.2.8 Defined and safe failure behaviour in the event of module defects................ 96
2.5.2.9 Environmentally compatible recycling............................................................ 96
2.5.3 Discrete devices .................................................................................................. 97
2.5.3.1 Small rectifiers ............................................................................................... 97
2.5.3.2 Stud-mounted diodes and stud thyristors....................................................... 98
2.5.3.3 Disk cells ....................................................................................................... 98
2.5.3.4 SEMiSTART® ................................................................................................ 99
2.5.4 Power modules.................................................................................................. 100
2.5.4.1 Basics.......................................................................................................... 100
2.5.4.2 Module families with rectifier diodes and thyristors ...................................... 101
2.5.4.3 Module families with IGBT and freewheeling diodes.................................... 104
2.6 Integration of sensors, protective equipment and
driver electronics .......................................................................................................110
2.6.1 Modules with integrated current measurement ...................................................110
2.6.2 Modules with integrated temperature measurement...........................................111
2.6.3 IPM (Intelligent Power Module)...........................................................................114
2.7 Reliability...................................................................................................................115
2.7.1 MTBF, MTTF and FIT rate ..................................................................................115
2.7.2 Accelerated testing according to Arrhenius.........................................................116
2.7.3 Standard tests for the product qualification and postqualification .......................117
2.7.3.1 High Temperature Reverse Bias Test (HTRB), High Temperature Gate Bias
Test (HTGB), High Humidity High Temperature Reverse Bias Test (THB).....118
2.7.3.2 High and low temperature storage (HTS, LTS) .............................................118
2.7.3.3 Temperature cycling test (TC).......................................................................118
2.7.3.4 Power cycling test (PC) ................................................................................119
2.7.3.5 Vibration test.................................................................................................119
2.7.4 Additional tests for spring contacts ................................................................... 120
2.7.4.1 Micro-vibration (fretting corrosion) .............................................................. 120
2.7.4.2 Corrosive atmosphere (pollution gas test) .................................................. 121
2.7.4.3 Contact-to-PCB temperature cycling............................................................ 121
2.7.5 Failure mechanisms during power cycling ......................................................... 122
2.7.6 Evaluation of temperature changes regarding module lifetime .......................... 126
3 Datasheet Ratings for MOSFET, IGBT, Diodes and Thyristors................................... 131
3.1 Standards, symbols and terms ................................................................................. 131
3.1.1 Standards .......................................................................................................... 131
3.1.2 Letter symbols and terms .................................................................................. 131
3.1.3 Maximum ratings and characteristics ................................................................ 133
3.1.4 Component (type) designation system .............................................................. 133
3.2 Rectifier diodes and thyristors .................................................................................. 134
3.2.1 Temperatures..................................................................................................... 134
3.2.2 Thermal impedance and thermal resistance ..................................................... 136
3.2.3 Mechanical data ................................................................................................ 138
3.2.4 Rectifier diodes.................................................................................................. 138
3.2.4.1 Maximum ratings ......................................................................................... 138
3.2.4.2 Characteristics............................................................................................. 141
3.2.4.3 Diagrams ..................................................................................................... 145
3.2.5 Thyristors........................................................................................................... 146
3.2.5.1 Maximum ratings ......................................................................................... 146
3.2.5.2 Characteristics............................................................................................. 148
3.2.5.3 Diagrams ..................................................................................................... 156
3.2.6 Diode and thyristor modules .............................................................................. 157
3.2.6.1 Maximum ratings and characteristics........................................................... 157
3.2.6.2 Diagrams ..................................................................................................... 157
3.3 IGBT modules .......................................................................................................... 158
3.3.1 Maximum ratings ............................................................................................... 160
III
3.3.1.1 IGBT maximum ratings ................................................................................ 160
3.3.1.2 Maximum ratings of integrated inverse diodes (freewheeling diodes).......... 162
3.3.1.3 Maximum module ratings............................................................................. 163
3.3.2 Characteristics................................................................................................... 163
3.3.2.1 IGBT characteristics .................................................................................... 164
3.3.2.2 Characteristics of integrated hybrid inverse diodes (freewheeling diodes)... 170
3.3.2.3 Module layout characteristics ...................................................................... 172
3.3.3 Diagrams ........................................................................................................... 173
3.3.4 Safe operating areas during switching operation............................................... 181
3.3.4.1 Maximum safe operating area during single-pulse operation and periodic
turn-on (SOA) .............................................................................................. 181
3.3.4.2 Turn-off safe operating area (RBSOA)......................................................... 182
3.3.4.3 Safe operating area during short circuit ....................................................... 183
3.4 Power MOSFET modules ........................................................................................ 184
3.4.1 Maximum ratings ............................................................................................... 184
3.4.1.1 Maximum forward ratings of power MOSFET ............................................. 184
3.4.1.2 Maximum ratings of the inverse diodes (power MOSFET ratings in reverse
direction) ..................................................................................................... 185
3.4.1.3 Maximum module ratings............................................................................. 185
3.4.2 Characteristics................................................................................................... 186
3.4.2.1 Power MOSFET characteristics ................................................................... 186
3.4.2.2 Characteristics of inverse diodes (power MOSFET in reverse direction) .... 189
3.4.2.3 Mechanical module data.............................................................................. 190
3.4.3 Diagrams ........................................................................................................... 190
3.5 Supplementary information on CI, CB and CIB power modules ............................... 196
3.6 Supplementary information on IPMs ........................................................................ 198
3.6.1 Maximum ratings of the power section .............................................................. 201
3.6.2 Maximum ratings of a SKiiP driver..................................................................... 201
3.6.3 Characteristics of the SKiiP power section ........................................................ 203
3.6.4 SKiiP driver characteristics ............................................................................... 205
4 Application Notes for Thyristors and Rectifier Diodes............................................... 209
4.1 Thyristor and Rectifier Dimensioning and Selection ................................................. 209
4.1.1 Reverse voltage................................................................................................. 209
4.1.2 Rectifier diodes.................................................................................................. 210
4.1.2.1 Thermal load in continuous duty .................................................................. 210
4.1.2.2 Operation with short-time and intermittent load ............................................211
4.1.2.3 Load at higher frequencies .......................................................................... 212
4.1.2.4 Rated surge forward current for times below and above 10 ms .................. 212
4.1.3 Thyristors........................................................................................................... 213
4.1.3.1 Load in continuous duty .............................................................................. 213
4.1.3.2 Operation with short-time and intermittent load ........................................... 215
4.1.3.3 Maximum surge on-state current for times below and above 10 ms ............ 216
4.1.3.4 Critical rate of rise of current and voltage ................................................... 216
4.1.3.5 Firing properties .......................................................................................... 217
4.1.4 Thyristor diode modules ................................................................................... 217
4.1.5 Bridge Rectifiers ................................................................................................ 219
4.1.6 SemiSel dimensioning software......................................................................... 219
4.2 Cooling rectifier components .................................................................................... 222
4.2.1 Cooling low-power components ........................................................................ 222
4.2.2 Cooling plates ................................................................................................... 222
4.2.3 Heatsinks........................................................................................................... 225
4.2.4 Enhanced air cooling ......................................................................................... 227
4.2.5 Disc cells: water cooling .................................................................................... 230
4.3 Drivers for thyristors ................................................................................................. 230
4.3.1 Drive pulse shape.............................................................................................. 230
IV 4.3.2 Driving six-pulse bridge circuits ......................................................................... 233
4.3.3 Pulse transformers ............................................................................................ 233
4.3.4 Pulse generation................................................................................................ 234
4.4 Fault behaviour and diode / thyristor protection........................................................ 234
4.4.1 General voltage surge protection....................................................................... 234
4.4.2 Overvoltage protection using resistors and capacitors ...................................... 235
4.4.2.1 Snubbers for single switches ...................................................................... 235
4.4.2.2 AC side snubber ......................................................................................... 240
4.4.2.3 DC side snubber circuits.............................................................................. 244
4.4.3 Overvoltage protection using varistors............................................................... 245
4.4.4 Snubber circuits based on siIicon avalanche diodes ......................................... 246
4.4.4.1 AvaIanche rectifier diodes featuring self-protection .................................... 246
4.4.4.2 Avalanche diodes as protection for other components ................................ 247
4.4.4.3 Restrictions in application range ................................................................. 247
4.4.4.4 Case types .................................................................................................. 248
4.4.5 Overcurrent protection for diodes and thyristors................................................ 248
4.4.5.1 Devices for protection from overcurrents .................................................... 248
4.4.5.2 Protective devices for malfunctions in the cooling device ........................... 249
4.4.5.3 Devices that respond to both overcurrent and cooling unit malfunctions .... 249
4.4.6 Short-circuit protection for diodes and thyristors................................................ 250
4.4.6.1 Semiconductor fuses: terms and explanations............................................. 251
4.4.6.2 Dimensioning semiconductor fuses ............................................................. 254
4.5 Series and parallel connection of diodes and thyristors............................................ 260
4.5.1 Parallel connection of thyristors......................................................................... 260
4.5.2 Series connection of thyristors........................................................................... 260
4.5.3 Parallel connection of rectifier diodes ................................................................ 260
4.5.4 Series connection of rectifier diodes.................................................................. 260
5 Application Notes for IGBT and MOSFET Modules .................................................... 261
5.1 Selecting IGBT and MOSFET modules .................................................................... 261
5.1.1 Operating voltage .............................................................................................. 261
5.1.1.1 Blocking voltage .......................................................................................... 261
5.1.1.2 Co-ordination of insulation ........................................................................... 265
5.1.2 On-state current ................................................................................................ 268
5.1.3 Stress conditions of freewheeling diodes in rectifier and inverter mode............. 269
5.1.4 Switching frequency ......................................................................................... 271
5.2 Thermal dimensioning for power transistor modules ................................................ 273
5.2.1 Individual and total losses ................................................................................. 274
5.2.1.1 DC/DC converters........................................................................................ 275
5.2.1.2 PWM voltage inverter .................................................................................. 277
5.2.2 Junction temperature calculation ....................................................................... 279
5.2.2.1 Thermal equivalent circuit diagrams ............................................................ 279
5.2.2.2 Junction temperature during stationary operation (mean-value analysis) .... 282
5.2.2.3 Junction temperature during short-time operation........................................ 283
5.2.2.4 Junction temperature at fundamental frequency .......................................... 285
5.2.3 Calculation of power dissipation and temperature using SemiSel ..................... 287
5.2.3.1 Possible solution for temperature and power dissipation calculation ........... 287
5.2.3.2 Circuit selection ........................................................................................... 288
5.2.3.3 Electrical operating conditions ..................................................................... 288
5.2.3.4 Component selection ................................................................................... 289
5.2.3.5 Thermal operating conditions....................................................................... 290
5.2.3.6 Results......................................................................................................... 292
5.3 Cooling power modules............................................................................................ 294
5.3.1 Thermal model of the cooling system ................................................................ 294
5.3.2 Factors influencing thermal resistance .............................................................. 295
5.3.2.1 Number of heat sources............................................................................... 295
V
5.3.2.2 Heat spreading ............................................................................................ 296
5.3.2.3 Position of heat sources in relation to direction of cooling flow .................... 297
5.3.2.4 Measuring points for determining Rth .......................................................... 297
5.3.3 Natural air cooling (free convection).................................................................. 298
5.3.4 Forced air cooling ............................................................................................. 298
5.3.4.1 Cooling profiles............................................................................................ 299
5.3.4.2 Pressure drop and air volume...................................................................... 300
5.3.4.3 Fans (ventilators, blowers)........................................................................... 301
5.3.4.4 Operating height .......................................................................................... 302
5.3.5 Water cooling .................................................................................................... 303
5.3.5.1 Pressure drop and water volume, test pressure........................................... 305
5.3.5.2 Coolant, cooling cycle and chemical requirements ...................................... 306
5.3.5.3 Mounting direction and venting .................................................................... 308
5.3.5.4 Other liquid cooling possibilities................................................................... 309
5.3.6 Heatpipes .......................................................................................................... 312
5.3.7 Thermal stacking ............................................................................................... 313
5.3.7.1 Determining an additional thermal impedance............................................. 313
5.3.7.2 Calculating pre-heating for air cooling ......................................................... 314
5.3.7.3 Calculating pre-heating for water cooling..................................................... 315
5.4 Power design, parasitic elements, EMC................................................................... 316
5.4.1 Parasitic inductances and capacitances ............................................................ 316
5.4.2 EMI and mains feedback ................................................................................... 318
5.4.2.1 Energy processes in converters................................................................... 318
5.4.2.2 Causes of interference currents................................................................... 319
5.4.2.3 Propagation paths........................................................................................ 321
5.4.2.4 Other causes of electromagnetic interference (EMI).................................... 323
5.4.2.5 EMI suppression measures ......................................................................... 323
5.5 STACKs.................................................................................................................... 325
5.5.1 Definition of the term "STACK" .......................................................................... 325
5.5.2 Platforms ........................................................................................................... 325
5.5.2.1 Platform SEMIKUBE with IGBT standard modules ...................................... 326
5.5.2.2 STACK platforms with SKiiP IPM modules................................................... 327
5.5.2.3 Examples of platform solutions for line-commutated circuits using
thyristors or diodes ...................................................................................... 330
5.5.3 SKAI: System assemblies for vehicle applications............................................. 332
5.6 Driver ....................................................................................................................... 333
5.6.1 Gate current and gate voltage characteristics ................................................... 333
5.6.2 Driver parameters and switching properties ...................................................... 337
5.6.3 Driver circuit structures...................................................................................... 340
5.6.4 Protection and monitoring functions................................................................... 342
5.6.5 Time constants and interlock functions.............................................................. 343
5.6.6 Transmission of driver signal and driving energy............................................... 345
5.6.6.1 Driver control and feedback signals............................................................. 346
5.6.6.2 Driving energy ............................................................................................. 347
5.6.7 Monolithic and hybrid driver ICs ........................................................................ 348
5.6.8 SEMIDRIVER .................................................................................................... 349
5.7 Error behaviour and protection................................................................................. 352
5.7.1 Types of faults/errors ......................................................................................... 352
5.7.2 Behaviour in the event of overload or short circuit............................................. 355
5.7.3 Fault detection and protection ........................................................................... 359
5.7.3.1 Detection and reduction of fault currents ..................................................... 360
5.7.3.2 Overvoltage limitation .................................................................................. 362
5.7.3.3 Overtemperature detection .......................................................................... 370
5.8 Parallel and Series Connections .............................................................................. 370
5.8.1 Parallel connection ........................................................................................... 370
VI
5.8.1.1 Problems involved with current balancing.................................................... 370
5.8.1.2 Ways of improving current symmetry ........................................................... 378
5.8.1.3 Derating....................................................................................................... 380
5.8.1.4 Specifics of parallel connections for SKiiP modules .................................... 381
5.8.2 Series connection.............................................................................................. 382
5.8.2.1 The importance of voltage symmetry ........................................................... 383
5.8.2.2 Ways of improving voltage symmetry........................................................... 384
5.8.2.3 Conclusions ................................................................................................. 389
5.9 Soft switching as ZVS or ZCS / switching loss reduction networks (snubbers)......... 389
5.9.1 Aims and areas of application............................................................................ 389
5.9.2 Switching loss reduction networks / snubber circuits ......................................... 389
5.9.3 Soft switching .................................................................................................... 391
5.9.3.1 Load on power semiconductors ................................................................... 391
5.9.3.2 Semiconductor and driver requirements ...................................................... 395
5.9.3.3 Switching properties .................................................................................... 397
5.9.3.4 Conclusion................................................................................................... 402
6 Handling instructions and environmental conditions ............................................... 403
6.1 Sensitivity to ESD and measures for protection ...................................................... 403
6.2 Ambient conditions for storage, transportation and operation ................................. 403
6.2.1 Climatic conditions............................................................................................. 405
6.2.2 Mechanical environmental conditions ................................................................ 405
6.2.3 Biological environmental conditions................................................................... 407
6.2.4 Environmental impact due to chemically active substances .............................. 407
6.2.5 Environmental impact caused by mechanically active substances .................... 407
6.2.6 Notes on operation at high altitudes .................................................................. 408
6.2.7 Air humidity limits and condensation protection................................................. 410
6.2.8 Ramifications for design process........................................................................411
6.3 Power module assembly .......................................................................................... 413
6.3.1 Quality of the heat sink mounting surface.......................................................... 413
6.3.2 Thermal coupling between module and heat sink by means of thermal
interface material (TIM) ..................................................................................... 414
6.3.3 Mounting power modules onto heat sink ........................................................... 419
6.3.4 Electrical connections........................................................................................ 420
6.4 Mounting of capsule diodes and thyristors (disc cells).............................................. 421
7 Software tool as a dimensioning aid ........................................................................... 425
7.1 SemiSel ................................................................................................................... 425
7.1.1 Program functions ............................................................................................. 426
7.1.2 Using SemiSel................................................................................................... 426
7.2 Semiconductor models............................................................................................. 427
7.2.1 Static models..................................................................................................... 427
7.2.2 State models ..................................................................................................... 428
7.2.3 Physical models of semiconductor and behaviour models................................ 429
References ......................................................................................................................... 431
Abbreviations used in SEMIKRON Datasheets................................................................ 436
Index ................................................................................................................................... 449
