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Aut o moti ve I GB T M odule BDTIC Applic atio n N ote Explanation of Technical Information AN 201 0 -0 9 Revison 1.0 Elect ric D rive T rain www.BDTIC.com/infineon BDTIC Edition Revison 1.0 Published by Infineon Technologies AG 81726 Munich, Germany © 2010 Infineon Technologies AG All Rights Reserved. LEGAL DISCLAIMER THE INFORMATION GIVEN IN THIS DOCUMENT IS GIVEN AS A HINT FOR THE IMPLEMENTATION OF THE INFINEON TECHNOLOGIES COMPONENT ONLY AND SHALL NOT BE REGARDED AS ANY DESCRIPTION OR WARRANTY OF A CERTAIN FUNCTIONALITY, CONDITION OR QUALITY OF THE INFINEON TECHNOLOGIES COMPONENT. THE RECIPIENT OF THIS DOCUMENT MUST VERIFY ANY FUNCTION DESCRIBED HEREIN IN THE REAL APPLICATION. INFINEON TECHNOLOGIES HEREBY DISCLAIMS ANY AND ALL WARRANTIES AND LIABILITIES OF ANY KIND (INCLUDING WITHOUT LIMITATION WARRANTIES OF NON-INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OF ANY THIRD PARTY) WITH RESPECT TO ANY AND ALL INFORMATION GIVEN IN THIS DOCUMENT. Information For further information on technology, delivery terms and conditions and prices, please contact the nearest Infineon Technologies Office (www.infineon.com). Warnings Due to technical requirements, components may contain dangerous substances. For information on the types in question, please contact the nearest Infineon Technologies Office. Infineon Technologies components may be used in life-support devices or systems only with the express written approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the failure of that life-support device or system or to affect the safety or effectiveness of that device or system. Life support devices or systems are intended to be implanted in the human body or to support and/or maintain and sustain and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other persons may be endangered. www.BDTIC.com/infineon Automotive IGBT Module Explanation of Technical Information Document Change History Date 12-08-2010 Version 1.0 Changed By T. Reiter Change Description Initial Version We Listen to Your Comments Is there any information in this document that you feel is wrong, unclear or missing? Your feedback will help us to continuously improve the quality of this document. Please send your proposal (including a reference to this document) to: [email protected] BDTIC Trademarks of Infineon Technologies AG AURIX™, BlueMoon™, COMNEON™, C166™, CROSSAVE™, CanPAK™, CIPOS™, CoolMOS™, CoolSET™, CORECONTROL™, DAVE™, EasyPIM™, EconoBRIDGE™, EconoDUAL™, EconoPACK™, EconoPIM™, EiceDRIVER™, EUPEC™, FCOS™, HITFET™, HybridPACK™, ISOFACE™, I²RF™, IsoPACK™, MIPAQ™, ModSTACK™, my-d™, NovalithIC™, OmniTune™, OptiMOS™, ORIGA™, PROFET™, PRO-SIL™, PRIMARION™, PrimePACK™, RASIC™, ReverSave™, SatRIC™, SIEGET™, SINDRION™, SMARTi™, SmartLEWIS™, TEMPFET™, thinQ!™, TriCore™, TRENCHSTOP™, X-GOLD™, XMM™, X-PMU™, XPOSYS™. Other Trademarks Advance Design System™ (ADS) of Agilent Technologies, AMBA™, ARM™, MULTI-ICE™, PRIMECELL™, REALVIEW™, THUMB™ of ARM Limited, UK. AUTOSAR™ is licensed by AUTOSAR development partnership. Bluetooth™ of Bluetooth SIG Inc. CAT-iq™ of DECT Forum. COLOSSUS™, FirstGPS™ of Trimble Navigation Ltd. EMV™ of EMVCo, LLC (Visa Holdings Inc.). EPCOS™ of Epcos AG. 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VERILOG™, PALLADIUM™ of Cadence Design Systems, Inc. VLYNQ™ of Texas Instruments Incorporated. VXWORKS™, WIND RIVER™ of WIND RIVER SYSTEMS, INC. ZETEX™ of Diodes Zetex Limited. Application Note Explanation of Technical Information 3 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Table of Contents Page 1 Abstract .......................................................................................................................................... 5 2 2.1 2.2 Introduction ................................................................................................................................... 5 Status of datasheets ....................................................................................................................... 5 Type Designations .......................................................................................................................... 6 3 3.1 3.2 3.3 3.4 3.5 3.6 3.6.1 3.6.2 3.7 3.7.1 3.7.2 3.7.3 3.8 3.9 3.10 3.11 Datasheet parameters IGBT ......................................................................................................... 7 Collector-emitter voltage VCES ......................................................................................................... 7 Total power dissipation Ptot ............................................................................................................. 7 Collector current IC .......................................................................................................................... 7 Repetitive peak collector current ICRM ............................................................................................. 8 Reverse bias safe operating area RBSOA ..................................................................................... 8 Typical output and transfer characteristics ..................................................................................... 9 IGBT device structure and difference in output characteristic of power MOSFETs and IGBTs. .... 9 Transfer and output characteristics (IGBT datasheet) ..................................................................10 Parasitic capacitances ..................................................................................................................12 Measurement circuits ....................................................................................................................13 Gate charge Qg and gate current .................................................................................................14 Parasitic turn-on ............................................................................................................................15 Switching times .............................................................................................................................16 Short circuit ...................................................................................................................................18 Leakage currents ICES and IGES ......................................................................................................19 Thermal characteristics .................................................................................................................19 4 4.1 4.2 4.3 4.4 Datasheet parameters Diode......................................................................................................21 Forward current IF and forward characteristic ...............................................................................21 Repetetive peak forward current IFRM ............................................................................................21 Reverse recovery ..........................................................................................................................21 Thermal characteristics .................................................................................................................23 5 5.1 5.2 Datasheet parameters NTC-thermistor .....................................................................................24 NTC resistance..............................................................................................................................24 B-values ........................................................................................................................................24 6 6.1 6.2 6.3 6.4 6.5 Datasheet parameters Module ...................................................................................................25 Insulation voltage VISOL .................................................................................................................25 Stray inductance LS .......................................................................................................................25 Module resistance RCC’+EE’ ............................................................................................................26 Cooling circuit ................................................................................................................................27 Mounting torque M ........................................................................................................................28 7 References ...................................................................................................................................28 BDTIC Application Note Explanation of Technical Information 4 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Abstract 1 Abstract Note: The following information is given as a hint for the implementation of the device only and shall not be regarded as a description or warranty of a certain functionality, condition or quality of the device. This Application Note is intended to provide an explanation of the parameters and diagrams given in the datasheet of automotive IGBT modules. With the Application Note the designer of power electronic components requiring an IGBT module is able to use the datasheet in the right way and will be provided with background information. 2 Introduction Each parameter mentioned in the datasheet gives values which characterizes the module as detailed as possible. With this information the designer should be able on the one hand side to compare devices from different competitors with each other, on the other hand side the information should be sufficient to figure out where the limits of the device are. This document helps to understand the datasheet parameter and characteristics much better. It explains the interaction between the parameters and the influence of the conditions like temperature. Datasheet values that refer to dynamical characterization tests, e.g., switching losses, are related to a specific test setup with defined stray inductance, gate resistance, etc. .Therefore, these values can deviate from a final user application. BDTIC The attached diagrams, tables and explanations are referring to the datasheet of FS800R07A2E3 (rev.1.4 from 2009-04-20) as example. The shown values and characteristics are not feasible to use for design-in activities. For the latest version of datasheets please refer to our webpage (www.infineon.com/hybrid). 2.1 Status of datasheets Depending on the status of the product development, the relating technical information contains: Target data Preliminary data Final data Target data describes the design goal of the future product. Preliminary data is based on components produced from series tools. The manufacturing is close to production, but partly in laboratory. Mechanical, thermal and electrical data can change slightly during the further development process. Reliability and lifetime partly, not finally approved for IGBT module. Final data is based on final components. Manufacturing is done under series conditions considering productive tooling for mass production. Mechanical, thermal and electrical data are fixed. Reliability and lifetime is approved and released. Application Note Explanation of Technical Information 5 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Introduction 2.2 Type Designations FS800R07A2E3 Chip Type Module Type Blocking Voltage Conducting Type Current Rating Module Topology Module Topology Designation Description FS SixPACK / B6-bridge FF Halfbridge (two IGBT’s and freewheeling diodes) FZ Single switch with IGBT and freewheeling diode F4 H-Bridge FD/DF Chopper or buck or boost-converter modules BDTIC Current Rating Designation Description 800 Implemented collector current [A] Conducting Type Designation Description R Reverse conducting T Bidirectional blocking switch Blocking Voltage Designation Description 07 Collector-emitter breakdown voltage in 100V. Value is rounded. Please refer to breakdown voltage in datasheet for real value. Module Type Designation Description Ax A: Automotive qualified package x=1: HybridPACK1 x=2: HybridPACK2 Wx W: Easy package x=1 EASY 1B x=2 EASY 2B Note: “A” as last character of the designation indicates an EASY Automotive power module Chip Type Designation Description EX Trench IGBT, fast switching and low Vce,sat x=1..n Internal reference Number Application Note Explanation of Technical Information 6 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT 3 Datasheet parameters IGBT 3.1 Collector-emitter voltage VCES The permissible peak collector emitter voltage is specified at a junction temperature of 25°C (see Figure 1). This value decreases for lower temperatures with a factor of approximately: . Figure 1 Collector-emitter voltage of the IGBT (datasheet) 3.2 Total power dissipation Ptot BDTIC This parameter describes the maximum feasible power dissipation over: the cooling fluid temperature (Figure 2), in case of power modules with a PinFin structure (RthJF). the module case temperature, in case of power modules with a flat base plate or without baseplate (RthJC). Therefore, the total power dissipation can be calculated in general with: (1) The considered HybridPACK™2 is a power module with a PinFin structure. The power dissipation is related to ∆T of junction and cooling fluid as well as thermal resistance between junction and cooling fluid (eq. (2)). Up to a cooling fluid temperature of 25°C, the power dissipation is specified at its maximum value (eq. (3)). With increasing cooling fluid temperature the power dissipation is decreasing. (2) (3) Figure 2 Maximum ratings for Ptot (datasheet) The feasible power dissipation of the diode chips can be calculated, respectively. However, thermal resistance of junction to cooling fluid of the diode has to be used for eq. (2), eq. (3). Please take note that the case temperature is higher than 25°C, if the fluid temperatue has a temperature of 25°C. Therefore, the current rating of a power module with PinFin structure seems to be lower in comparison to a module with a flat base plate. But since thermal resistance of case to heatsink is taken into account, the advantage of a PinFin structure becomes obvious. In chapter 3.11 you can find more detailed information about the thermal characteristic of a power module. 3.3 Collector current IC Based on total power dissipation the maximum permissible collector current rating of a module can be calculated with eq. (4). Thus, in order to give a current rating of a module, the corresponding junction and cooling fluid temperature has to be specified, as shown for example in Figure 3. Please note that current ratings without defined temperature conditions have no technical meaning at all. Application Note Explanation of Technical Information 7 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT (4) Since IC is not known in eq. (4), VCE sat @ IC is also not known, but can be found within few iterations [5]. The ratings of continous DC-collector current are calculated with maximum values for VCE sat to ensure the specified current rating, taken into account component tolerances. Figure 3 DC-collector current (datasheet) 3.4 Repetitive peak collector current ICRM BDTIC The nominal current rating can be exceeded in an application for a short time. This is defined as repetitive peak collector current in the datasheet (see Figure 4) for the specified pulse duration. In theory, this value can be derived from the feasible power dissipation and the thermal impedance Zth, if the duration of the overcurrent condition is defined. However, this theoretical value is not taken into account any limitations of bond wires, bus-bars, power connectors, etc. Therefore, the datasheet value is quite low compared to a theoretical calculated value, but it specifies a safe operation considering all practical limitations of the power module. Figure 4 Repetitive peak collector current (datasheet) 3.5 Reverse bias safe operating area RBSOA The reverse bias safe operating area describes safe operating conditions at turn-off for the IGBT of the power module. The chip can be driven within its specified blocking voltage up to twice its nominal current rating, since the maximal junction temperature defined for switching operation is not exceeded. The safe operating area of the power module is limited due to stray inductances. With increasing switching currents, the allowed collector-emitter voltage is decreased. Furthermore, this degradation strongly depends on system related parameters, like stray inductance of the DC-Link capacitor and the current commutation slope during the switing transitions. The DC-Link capacitor is assumed to be ideal for this operating area. The current commutation slope is defined via a specified gate resistance and gate driving voltage, as noted within the testparametes in the diagram of Figure 5. Application Note Explanation of Technical Information 8 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT BDTIC Figure 5 Reverse bias safe operating area (datasheet) 3.6 Typical output and transfer characteristics The data of typical output and transfer characteristics can be used to calculate conduction losses of the IGBT. In order to contribute to a much better understanding of these parameters, the IGBT device structure as well as difference in output characteristic to a power MOSFET is discussed briefly. After this, the datasheet parameters of the IGBT module are explained. 3.6.1 IGBT device structure and difference in output characteristic of power MOSFETs and IGBTs. Figure 6 Structure of Trench-Field-Stop IGBT and two-transistor equivalent circuit (a). Comparative output characteristics of a power MOSFET and IGBT (b).Figure 6a shows the structure of a trench-field-stop IGBT with a simplified two-transistor equivalent circuit. The pn-junction of the pnp bipolar transistor, which is located on the collector side of the IGBT, leads to a diode voltage drop, when IGBT is in conducting mode. The intrinsic bipolar transistor of the IGBT is driven by a MOSFET. Therefore, the gate driving characteristic is quite similar to a power MOSFET. But the output characteristic is different, which is illustrated in Figure 6b schematically. It shows the characteristic of turned-on devices at two two different junction temperatures. As shown in Figure 6b, the MOSFET is reverse conducting for negative drain-to-source voltages due to its intrinsic body diode. The IGBT has no body diode and thus an anti-parallel diode has to be used, when this operating mode is required. The advantage is that the external diode can be optimized separately to the IGBT. In conducting state (i.e. positive drain-to-source or collector-emitter voltage), the main difference of these devices is, that the MOSFET is an unipolar device and leads to an output characteristics, which can be modelled as an ohmic resistance (Rds(on)). In contrast to the MOSFET, the IGBT has a diode voltage drop. As a result, at very light load conditions (indicated with 1 in Figure 6b) the MOSFET always has lower conduction losses than an IGBT. Both output characteristics depend on the junction temperature. The Rds(on) of a MOSFET typically increases of a factor of about two, when the junction temperature increases from 25°C to 150°C. In contrast to this, the temperature coefficients of an IGBT are much lower. At light load conditions, the conduction losses even decreases with increasing temperature, due to the lower voltage drop of the pn-junction (see curves at currents below the indicated operating point with 2 in Figure 6b). At higher currents, the increase of Application Note Explanation of Technical Information 9 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT the ohmic resistance is dominant. Due to this, a parallel connection of several IGBTs is possible and is commonly required for high current IGBT power modules. a) b) Emitter IGBT Gate ICE IDS IC Tj1 Tj2 VCE + + nn p+ p+ MOSFET ID VDS 2 Tj2 Tj1 1 BDTIC n- n Collector (substrate) Tj1 (fieldstop) Tj2 Tj1 < Tj2 VCE VDS p+ Figure 6 Structure of Trench-Field-Stop IGBT and two-transistor equivalent circuit (a). Comparative output characteristics of a power MOSFET and IGBT (b). 3.6.2 Transfer and output characteristics (IGBT datasheet) The transfer characteristic shows, that the turn-on threshold voltage decreases with the junction temperature Figure 7. Since the turn-on threshold voltage is far from zero, high junction temperature will not self turn-on the IGBT even if zero gate drive voltage is used. Application Note Explanation of Technical Information 10 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT BDTIC Figure 7 Typical tansfer characteristic (datasheet). As discussed in chapter 3.6.1, the output characteristic of the IGBT depends on the temperature of the junction. Figure 8a shows the collector current in conducting state characterized over the collector-emitter voltage at different junction temperatures. For currents lower than about 300 A, the conduction losses decrease with inceasing temperature. For higher currents, the conduction losses increase slightly. In the considered case an increase in conduction losses of about 15% at nominal current rating (800 A) and a temperature increase from 25°C to 150°C can be oberserved. Application Note Explanation of Technical Information 11 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT a) b) BDTIC Linear mode Figure 8 Typical output characteristics over temperature (a) and gate-emitter voltage variation (b) (datasheet) Figure 8b shows the typical output characteristic for different gate-emitter voltages. The IGBT should not be operated in linear mode, as this causes excessive conduction losses. If the power dissipation is not limited in value and time, the device might be failing. Using 15 V as typical gate drive voltage, such a linear mode only occurs for short periods at the switching transitions, which is a normal operating condition for the IGBT. 3.7 Parasitic capacitances The dynamical characteristics of an IGBT is influenced by parasitic capacitances. A common behavioural model with three capacitances is shown in Figure 9. The shown input capacitance Cies and the reverse transfer capacitance Cres are useful for an adequate dimensioning of the gate driving circuit. The output capacitance Coss limits the dV/dt at switching transistions, whereby Coss related power losses can be usually neglected in applications using IGBTs. CGC= Cres CCE= Coss-Cres CGE= Cies-Cres Figure 9 Parasitic capacitances of an IGBT. Application Note Explanation of Technical Information 12 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT 3.7.1 Measurement circuits The values of the parasitic capacitances strongly depend on the operating point of the IGBT (i.e. voltage dependent). In order to measure these capacitances at biased gate or collector-emitter voltages, following measurement circuits are applied (see Figure 10). Input capacitance Cies (Figure 10a): The input capacitance Cies is measured at a biased collector-emitter voltage of typically 25V. The gateemitter voltage is typically set to zero. An inductor is used to keep AC-currents from the gate-emitter voltage source away from the capacitance bridge. Output capacitance Coss (Figure 10b): The output capacitance Coss is measured at biased collector-emitter voltages. An inductor is used to keep AC-currents from the collector-emitter voltage source away from the capacitance bridge. Reverse transfer capacitance Cres (Figure 10c): The reverse transfer capacitance Cres is measured at a biased collector-emitter voltage of typically 25V. The gate-emitter voltage is typically set to zero. Inductors are used to keep AC-currents from the gate-emitter and collector-emitter voltage source away from the capacitance bridge. BDTIC Application Note Explanation of Technical Information 13 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT a) DUT C1 Capacitance bridge E.g. HP4280A VCE L C2 VGE b) BDTIC DUT C3 L VGE C1 C2 c) Capacitance bridge E.g. HP4280A VCE DUT R1 L2 ID R2 L1 C2 VGE C1 VCE Capacitance bridge E.g. HP4280A Figure 10 Basic circuit diagram for measuring the input capacitance C ies (a), output capacitance Coss (b), and reverse transfer capacitance Cres (c). 3.7.2 Gate charge Qg and gate current The value of the gate charge is useful to design the gate driving circuit. The average output power that the gate driving circuit has to deliver can be calculated with data of the gate charge, gate drive voltages and switching frequency (eq.(5)). (5) Using for example 10 kHz and 15 V positive and negative gate driving voltages, the required output power of the gate driving circuit can be calculated with eq.(6) (Figure 11). (6) Application Note Explanation of Technical Information 14 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT Figure 11 Gate charge and internal gate resistor (datasheet). The theoretical gate drive peak current can be calculated with data of the gate drive voltages and gate resistances, which is the sum of external and internal gate drive resistance (eq. (7), Figure 11): (7) In practice this peak current will not be achieved, because it is limited by stray inductances and non-ideal switching transitions of a real gate driving circuit. BDTIC 3.7.3 Parasitic turn-on With the parasitic capacitances of the IGBT, characterized in the datasheet, dV/dt induced parasitic turn-on phenomena can be discussed. The cause of a possible parasitic turn-on is based on the intrinsic capacitive voltage divider between collector-gate and gate-emitter (see Figure 9). In consideration of high voltage transients across collector-emitter, this intrinsic capacitive voltage divider is much faster than an external gate driving circuit, which is limited by parasitic inductances. Therefore, even if the gate driver switches the IGBT off, i.e., zero gate-emitter voltage, transients of collector-emitter voltage lead to gate-emitter voltages, which are unequal to the driving voltage. Neglecting the influence of the gate driving cicuit, the gate-emitter voltage can be calculated with: (8) As a result, the quotient Cres/Cies should be as low as possible in order to avoid a parasitic dV/dt induced turn-on (quotient is about 35, see Figure 12). Furthermore, the input capacitance should be as low as possible to avoid gate driving losses. Figure 12 Parasitic capacitances of the IGBT (datasheet). The parasitic capacitances are characterized at a constant collector-emitter voltage of 25 V (see Figure 12). The gate-emitter capacitance can be approximated as constant over the collector-emitter voltage (eq. (9)). The reverse transfer capacitance strongly depends on the collector-emitter voltage and can be estimated with eq. (10) (see Figure 13): (9) (10) Application Note Explanation of Technical Information 15 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT 102 CGE C [nF] 101 CGE 100 10-1 0 25 100 200 300 400 VCE [V] 500 600 700 BDTIC Figure 13 Approximation of input and reverse transfer capacitance over collector-emitter voltage according to eq. (9) and (10). Consequently, the robustness against dV/dt induced parasitic turn-on increases with the collector-emitter voltage (see eq. (8)). A low impedance (i.e. low stray inductance) gate driving circuit also minimizes the risk of parasitic turn-on events. 3.8 Switching times The switching times in the datasheet provides useful information in order to determine an appropriate dead time between turn-on and turn-off of the complementary devices in a half bridge configuration. Please refer to [1] for further information about setting appropriate dead times. The switching times in the datasheet are defined as follows and are shown in Figure 14, schematically: Turn-on delay time (td on): 10% of gate-emitter voltage to 10% of collector current Rise time (tr): 10% to 90% of collector current Turn-off delay time (td off): 90% of gate-emitter voltage to 90% of collector current Fall time (tf): 90% to 10% of collector current The switching times wil not give reliable information about switching losses, because voltage rise and fall times as well as current tail is not characterized. Therefore, energy losses per pulse are characterized separately. Application Note Explanation of Technical Information 16 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT VGE 90% VGE 10% VGE t IC 90% IC 90% IC 10% IC 10% IC BDTIC 2% IC t VCE 10% VCE 2% VCE td on tr td off t tf P Eoff Eon t Figure 14 Schematic switching waveforms with definion of switching times and energy losses. The characterized switching losses per pulse are defined for the datasheet as the integral: (11) , The integration limits t1 and t2 are: Turn-on energy loss per pulse (Eon): 10% of collector current to 2% of collector-emitter voltage Turn-off energy loss per pulse (Eoff): 10% of collector-emitter voltage to 2% of collector current Switching times and thus energy losses per pulse strongly depend on a variety of application specific operating conditions, like gate driving circuit, layout, gate resistance, switching voltages and currents as well as junction temperature. Therefore, datasheet values can only give an indication for the switching performance of the power module. For more accurate values detailed simulations, taken into account application specific parameters or experimental investigations are necessary. Typically, switching times and energy losses per pulse are characterized at nominal operating conditions for different temperatures (Figure 15). The characterization of energy losses per pulse over the collector current and over the gate resistance (Figure 16) gives an indication of the switching performace under typical operating conditions. Application Note Explanation of Technical Information 17 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT BDTIC Figure 15 Switching times and energy losses (datasheet) a) b) Figure 16 Energy losses per pulse over the collector current and the gate resistance (datasheet) 3.9 Short circuit The short circuit characteristic strongly depends on application specific parameters, like temperature, stray inductances, gate driving circuits and the resisance of the short circuit. For device characterization a test setup as shown in Figure 17a is used. One IGBT is short circuited while the other IGBT is driven with a single pulse. The corresponding typical voltage and current waveforms are illustrated in Figure 17b. The current in the conducting IGBT increases rapidly with a current slope, that is dependent on parasitic inductances and the DC-Link voltage. Due to desaturation of the IGBT, the current is limited to about 5 times the nominal current (in case of IGBT3) and the collector-emitter voltage remains on the high level. The chip temperature increases during this short circuit due to high currents and thus power losses. Because of the Application Note Explanation of Technical Information 18 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT increasing chip temperature the current decreases slightly while operating in short circuit condition. At a defined time tp the IGBT is switched off, to avoid a device failure. a) b) V, I VCE IC ISC VGE VCE BDTIC 10% IC 10% IC VGE IC tp t Figure 17 Short circuit test setup (a) and typical voltage/current waveforms during short circuit test (b). The data of the measured short circuit test and the applied parameters are noted in the datasheet (see Figure 18). Figure 18 Short circuit data (datasheet) 3.10 Leakage currents ICES and IGES Two major types of leakage currents have to be considered. The value of collector-emitter cut-off current garantees the upper limit of leakage current, when IGBT is in blocking mode. The gate-emitter leakage current is measured at maximum gate-emitter voltage. If this value is exceeded, the gate oxide has failures and the device will fail. Figure 19 Leakage currents (datasheet) 3.11 Thermal characteristics The values of power dissipation and current ratings as discussed in chapter 3.2 and 3.3 have no meaning without specification of temperatures as well as thermal resistance. Therefore, in order to compare different devices it is also necessary to compare thermal characteristics. Information about the definition of junction temperatures can be found in [3] and the thermal modeling is discussed in [2]. In following selected aspects are discussed in order to give a good understanding of the meaning of the datasheet parameters. When power modules with a flat baseplate or discrete devices are characterized, junction, case, and heatsink temperatures are noted. In this case, the power module has a baseplate with PinFin structure and is cooled via cooling fluid. Therefore, the cooling fluid temperature is the equivalent value to the common Application Note Explanation of Technical Information 19 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters IGBT defined heatsink temperature. As a consequence, the thermal resistance of junction to cooling fluid is specified in the datasheet (Figure 20), whereby this value is dependend on cooling mixture and flow rate (Figure 21a). Figure 20 Thermal resistance IGBT, junction to cooling fluid (datasheet) Please take note that the resistance of junction to cooling fluid or junction to heatsink have to be considered, when performance of different power modules are compared. b) a) BDTIC Figure 21 Thermal resistance (a) and transient thermal impedance junction to cooling fluid (b) (datasheet). The power module consists of different materials, which have a specific thermal capacitance and resistance. As a result, the resistance at higher frequency is lower than the statical resistance. The thermal impedance can be modelled as shown in Figure 22. The coefficients for this thermal model are characterized in the datasheet (Figure 21b), whereby the values of the capacitances can be calculated with: (12) r1 r2 r3 r4 r5 c1 c2 c3 c4 c5 Tvj TF Figure 22 Transient thermal model. Application Note Explanation of Technical Information 20 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters Diode 4 Datasheet parameters Diode 4.1 Forward current IF and forward characteristic The diode forward current can be calculated similar to IGBT current rating (see chapter 3.3), whereby RthJF of the diode has to be used: (13) Figure 23 shows the typical forward characteristic of the implemented diode at different junction temperatures. A negative temperature coefficient of the diode forward voltage drop can be observed, which is characteristic for minority-carrier devices. Therefore, the conduction losses of the diode decrease with increasing temperatures. BDTIC Figure 23 Forward characteristic of diode (datasheet). 4.2 Repetetive peak forward current IFRM The repetitive peak forward current of the diode is specified accordingly to the IGBT. Please refer to chapter 3.4 for more information. 4.3 Reverse recovery - When diode is in conducting state the p-n junction is forward-biased (Figure 24). Holes are injected in the nregion and become minority carriers, which finally recombine with electrons from the n region. Before the diode can turn into blocking mode, the stored minority charge in n- region has to be reduced by active means or by passive means, via recombination. Both mechanisms occur simultaneously. The actively removed minority charge is called recovered charge (Q r). This charge causes a current overshoot at turn-on transition of the complementary switch in the half-bridge and causes power losses. Application Note Explanation of Technical Information 21 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters Diode IF + - n- p n + + - + + + - + - Minority carrier injection Recombination Figure 24 Power diode under forward-bias condition. A schematic current and voltage waveform of a soft-recovery (Emitter Controlled) diode during turn-off transition is shown in Figure 25. The characterized peak reverse recovery current IRM in datasheet (Figure 26), is defined as difference between the absolute negative current peak and zero current. The recovered charge Qr as characterized in datasheet (Figure 26), is the integral: BDTIC (14) , The integration limits are between zero current of diode and 2% of reverse recovery current peak as shown in Figure 25. IF VR IF 10% VR Qr IF = 0 2% IRM t IRM VR Prec Erec t Figure 25 Schematic voltage and current waveform of a soft-recovery diode during turn-off transition. The losses due to reverse recovery can be calculated with the recovered energy per pulse. The energy is defined as the integral: (15) , The integration limits are between 10% of diode reverse voltage and 2% of reverse recovery current peak. Application Note Explanation of Technical Information 22 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters Diode Figure 26 Reverse recovery current, charge, and energy (datasheet) The recovered charge and thus energy losses caused by the reverse recovery of the diode strongly depend on junction temperature as well as commutation slope. In order to give an indication of application specific energy losses, the losses per diode turn-off pulse are characterized in the datasheet as a function of diode forward currents as well as gate resistance of the switching IGBT. The variation in gate resistance is an equivalent to a variation in current commutation slopes. BDTIC Figure 27 Reverse recovery energy loss per pulse over diode conducting currents and gate resistance (datasheet) 4.4 Thermal characteristics The thermal characteristic of the diode is characterized similar to the IGBT. Please refer to chapter 3.11 for more information. Application Note Explanation of Technical Information 23 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters NTC-thermistor 5 Datasheet parameters NTC-thermistor 5.1 NTC resistance One of the most important parameters in power electronic devices is the chip temperature. In most cases, the chip temperature is measured indirectly via a NTC-thermistor. The temperature of the chips can be calculated using a thermal model and measuring the temperature at the NTC. Please refer to [4] for information about thermal model and temperature measurement. The resistance of the NTC can be calculated as a function of the NTC temperature T2: (16) The resistance ( ) at temperature measurement of the actual NTC-resistance ( is specified in the datasheet (Figure 28). With ), the actual temperature can be calculated with: BDTIC (17) The maximum relative deviation of the resistance is defined at a temperature of 100°C (see in Figure 28). In order to avoid self heating of the NTC, the power dissipation has to be limited. The power dissipation, which heat up the NTC of 1 K is specified in the datasheet (see in Figure 28). With this value the Rth of the NTC (NTC to cooling fluid) can be calculated with: (18) In order to achieve a self heating of the NTC of lower than 1K, the current through the NTC has to be limited to the value: (19) Figure 28 Characteristic values of NTC-thermistor (datasheet). 5.2 B-values In order to calculate the actual NTC resistance as well as temperature of the NTC, B-values are required. The B-value dependends on the considered temperature range. Typically a range of 25 to 100 degree Celsius is of interest and thus B25/100 has to be used. In case a lower temperature range is in focus, the Bvalues B25/80 or B25/50 can be used, which leads to more accurate calculation of the resistance. Figure 29 B-values of the NTC-thermistor (datasheet). Application Note Explanation of Technical Information 24 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters Module 6 Datasheet parameters Module 6.1 Insulation voltage VISOL The insulation of all terminals together to the baseplate is designed to achieve at least the basic isolation according to IEC61140 (see Figure 30). Figure 30 Insulation test voltage (datasheet). The rated test voltage in the datasheet is tested before and after reliability tests of the power module and is furthermore part of failure criteria of such stress tests. BDTIC The insulation between NTC and other connectors is designed only for a functional isolation (typically with 1.5kV). In case of failures (e.g. the gate driving circuit) a conducting path can be formed by moving bond wires that change their position during the failure event or by a plasma path forming as a consequence of arcing during failure. Therefore, if isolation requirements higher than a functional isolation have to be achieved, additional isolating barriers have to be added externally. Please refer to [4] for more information about using the NTC inside a power module. 6.2 Stray inductance LS Stray inductances lead to transient voltages at the switching transients and are a major source of EMI noise. Furthermore, in combination with parasitic capacitances of the components, they can lead to resonant circuits, which can cause voltage and current ringing at switching transients. The transient voltage due to stray inductances can be calculated with: (20) As a result, the stray inductances have to be minimized in order to reduce voltage overshoot at turn-off transitions. A simplified equivalent circuit of the module stray inductances is shown in Figure 31. The stray inductance of the module is the sum of stray inductances of one phase-leg between the power terminals (see eq. (21). (21) Since a real power module is not ideal symmetric, the stray inductance of each phase-leg is measured and the maximum value is noted in datasheet (see Figure 32). Application Note Explanation of Technical Information 25 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters Module P3 P2 L31 L32 L35 L33 P1 L21 L11 L22 L25 3 L23 2 L12 L15 1 L13 BDTIC L34 N3 L24 L14 N1 N2 Figure 31 Equivalent circuit of a Six-Pack configuration with parasitic inductances. The stray inductances between power terminals as well as diode and IGBT are simplified. Figure 32 Stray inductance of module (datasheet). 6.3 Module resistance RCC’+EE’ The lead resistance of the module is a further contributor to voltage drop and power losses. The specified value in the datasheet characterizes the lead resistance beween the power terminals of one switch (Figure 33). According to the equivalent circuit shown in Figure 34, the module lead resistance is defined as: (22) Figure 33 Module lead resistance (datasheet) Application Note Explanation of Technical Information 26 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information Datasheet parameters Module P3 P2 P1 C’ RCC’ C E 3 2 E’’ REE’’ RE’’E’ 1 E’ BDTIC N3 N1 N2 Figure 34 Equivalent circuit of module lead resistance. 6.4 Cooling circuit The specified value of the preasure drop in the cooling circuit is an important parameter for the design of the cooling system (see Figure 35). This preasure drop is given for typical cooling conditions, since a cooler as specified in the datasheet is applied (see Figure 36). The specified maximum pressure in the cooling circuit, as shown in Figure 35, must never been exceeded, even for test procedures! Exceeding the maxium pressure may bend the baseplate and the risk is a leakage of the cooling circuit. Figure 35 Pressure drop in and maximum pressure in cooling circuit (datasheet) Application Note Explanation of Technical Information 27 www.BDTIC.com/infineon AN2010-09, 2010 Automotive IGBT Module Explanation of Technical Information References BDTIC Figure 36 Cooler for characterization of thermal performance and pressure drop in cooling circuit (datasheet). 6.5 Mounting torque M The torque for the mechanical mouning and electrical connection of the module is specified in the datasheet (see Figure 37). These values are important to ensure the right clamping force of the module to the heatsink and to ensure a reliable electrical connection of bus-bars to the module. Detailed information and recommendations about the mounting processes are discussed in [6]. Figure 37 Mounting torque requirements (datasheet) 7 References The referenced application notes can be found at http://www.infineon.com [1] Infineon Application Note AP99007, “Deadtime calculation for IGBT Modules”. [2] Infineon Application Note, “Thermal Modeling of Power-electronic Systems” [3] Infineon Application Note AN2008-1, “Definition of junction temperature” [4] Infineon Application Note AN2009-10, “Using the NTC inside a power electronic module” [5] Infineon Application Note ANIP9931E, “Calculation of major IGBT operating parameters” [6] Infineon Application Note AN2009-11, “Mounting Instructions for HybridPACK™2 Module” Application Note Explanation of Technical Information 28 www.BDTIC.com/infineon AN2010-09, 2010 BDTIC w w w . i n f i n e o n . c o m www.BDTIC.com/infineon Published by Infineon Technologies AG