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IGBT Applications In HEV/EV
Renesas Electronics America Inc.
© 2012 Renesas Electronics America Inc. All rights reserved.
Renesas Technology & Solution Portfolio
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© 2012 Renesas Electronics America Inc. All rights reserved.
Analog and Power Automotive Products
30V - 1500V in Application
Optimized Processes
 Low voltage family optimized for
LEDQgd
Backlight
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 Separate family optimized for pure
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600V Discrete Devices
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Vce(on) optimized
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6 - 200mΩ Protected
High-side Drivers
 Scalable solutions for exterior lighting,
relays, solenoids…
 Ultra-low key-off leakage current
performance
 Robust protection against short-circuit
conditions
Products Addressing All
Major Vehicle Systems
 Crash-sensing chipset for airbag
applications
 Powertrain output load drivers,
direct gas injection…
 Battery management ICs, MOSFET
gate drivers
 Micro-isolator IGBT drivers for
high-voltage isolation
 Multi-chip Package devices for switch
input and load control
‘Enabling The Smart Society’
 Challenge:
Improve efficiency of HEV/EV automobiles.
 Solution:
Lower inverter losses by replacing MOSFET’s with IGBT’s in
high-current applications.
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© 2012 Renesas Electronics America Inc. All rights reserved.
Agenda
 The purposes of this presentation are:
 To discuss IGBT technology in general.
 To discuss the advances that have improved IGBT performance
and lowered costs.
 To discuss the definition and application of various IGBT
datasheet parameters.
 To discuss power losses in IGBT switching transistors.
 To discuss the use of IGBT transistors in HEV/EV applications.
 This presentation will focus on applying IGBT transistors in
3-phase inverters for PMSM motor applications.
 While the basic principles discussed in this presentation are
applicable to IGBT’s used in traction motor inverters, this
presentation will focus on lower power applications, which
predominantly use MOSFET’s at present.
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Switching Applications In HEV/EV
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Switching Applications In HEV/EV
Windshield
Wipers
Windshield
Washer
Fuel Pump
Battery Charger
A/C
Compressor
Traction Motor
Inverter
Cooling Fan
and Pump
Seat Adjust
Mirror Adjust
Motor/
Generator
Power
Steering
Regenerative Braking
Transmission Voltage Conversion
Oil Pump
 There are many applications in an HEV/EV that require switching
transistors:
 Inverter drives for PMSM motors.
 Switchmode DC-DC converters and battery chargers.
 Control of brushed DC motors.
 The move to a 48V on-board supply and technological advances in
IGBT design are making IGBT’s increasingly attractive in many of
these applications.
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© 2012 Renesas Electronics America Inc. All rights reserved.
IGBT Silicon Technology
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© 2012 Renesas Electronics America Inc. All rights reserved.
IGBT Silicon Structure
Symbol
Model
Structure
 Essentially, an IGBT is a PNP Darlington transistor in which the
bipolar input transistor has been replaced with a MOSFET.




An IGBT is applied like an NPN power transistor.
Does not conduct in the reverse direction (a MOSFET does).
Does not provide an inherent reverse diode (a MOSFET does).
Conducting voltage drop is like a diode – a fixed voltage plus a voltage
that is proportional to the log of the current.
– The conducting voltage drop for a MOSFET is like a resistor – a voltage that is
proportional to the current.
 Contains a parasitic thyristor structure that can latch “on”.
– Better control of geometries and doping levels has virtually eliminated this
potential problem.
– Still need to prevent narrow gate pulses to insure full switching transitions.
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© 2012 Renesas Electronics America Inc. All rights reserved.
IGBT Technology Advances – Field Stop
Drawing sizes reflect the relative wafer thickness of the technologies




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 NPT Technology
PT Technology
Non-Punch Through
Punch Through
 E-field dissipates in drift
E-field “punches through”
region – lengthens tail
drift region to buffer –
current, raises EOFF.
shortens tail current.
 Thick drift region raises
Thin drift region lowers
VCE(SAT).
VCE(SAT).
 Injection layer realized
Expensive epitaxial layer
by ion implantation, no
+
grown on p substrate.
epitaxial layer.
© 2012 Renesas Electronics America Inc. All rights reserved.
 FS Technology
Field Stop
 E-field “punches through”
drift region to buffer –
shortens tail current.
 Thinnest drift region
yields lowest VCE(SAT).
 No epitaxial layer.
 Wafers as thin as 80µm.
IGBT Technology Comparison
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IGBT Technology Advances – Trench Gate
Planar Gate
Trench Gate
 The IGBT saturation voltage, VCE(SAT), is a key figure of merit.
 One factor contributing to the IGBT saturation voltage is the MOSFET
channel voltage.
– The channel voltage is directly proportional to the channel length and
inversely proportional to the channel width.
 By burying the gate structure in a vertical trench, the channel geometry
can be optimized to reduce the IGBT saturation voltage by as much as
0.2V – down as low as 1.35V (typ).
 This increases the Gate-Emitter capacitance, CGE, by as much as a factor
of 3, which in turn increases requirements on the gate drive circuit.
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© 2012 Renesas Electronics America Inc. All rights reserved.
Understanding An IGBT Datasheet
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IGBT Datasheet Parameters
 The basic voltage and current parameters hold no real surprises.
 The reverse collector-emitter breakdown voltage often is left off of IGBT datasheets.
 15V to 30Vis typical.
 Thermal considerations will limit the max current to something well below the
current the ratings stated in a datasheet.
 VCE(SAT) is high for an NPN power transistor and low for a PNP power Darlington.
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© 2012 Renesas Electronics America Inc. All rights reserved.
IGBT Datasheet Parameters
 Cies = CGC + CGE with C-E shorted.
 Coes = CGC + CCE with G-E shorted.
 Cres = CGC with E grounded. Also
known as the Miller capacitance.
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© 2012 Renesas Electronics America Inc. All rights reserved.
 Qg = Total gate charge transferred
during a switching transition.
 Qge = Charge transferred before the
gate plateau voltage is reached (CGE).
 Qgc = Charge transferred as VCE
changes during switching (CGC).
IGBT Datasheet Parameters






tDON = turn-on delay = t3 – t1
tR = rise time = t4 – t3
tON = switch-on time = t7 – t1
tDOFF = turn-off delay = t9 – t8
tF = fall time = t10 – t9
tOFF = turn-off time = t11 – t8
 EON =
 EOFF =
 ETOTAL = EON + EOFF
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© 2012 Renesas Electronics America Inc. All rights reserved.
IGBT Datasheet Parameters
 The tail current is the final
decay of IC, shown to the right
of the center line in this graph.
 The tail current decay time is
a principle component of the
switching “deadtime”.
 The tail current decay time
adds to the effective IGBT
turn-off time and increases
EOFF.
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IGBT Power Loss Calculations
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IGBT Switching Loss
 Switching Loss
 During each switching event, there are transition periods when
both IC and VCE are significantly non-zero.
 EON is the energy (in Joules) that is dissipated in the IGBT
during the turn-on transition.
 EOFF is the energy (in Joules) that is dissipated in the IGBT
during the turn-off transition.
 ETOTAL is the total energy (in Joules) that is dissipated in the
IGBT during one complete switching cycle (EON plus EOFF).
 The total switching loss (in Watts) is ETOTAL multiplied by the
number of switching cycles per second (PWM base
frequency).
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© 2012 Renesas Electronics America Inc. All rights reserved.
IGBT Conduction Loss
Motor Phase Current
High-Side / Low-Side IGBT Conduction Loss
 On-state current flow through an IGBT switch is a function of the
PWM duty cycle and the commutation angle of the motor drive
current.
 The IGBT conduction loss (in Watts) is the integral of VCE(SAT) x IC
over one commutation cycle (in Joules), multiplied by the number
of commutation cycles per second.
 The total IGBT power loss is the sum of the switching loss and the
conduction loss.
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© 2012 Renesas Electronics America Inc. All rights reserved.
IGBT / MOSFET Comparison
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IGBT vs MOSFET Comparisons
 IGBT
 Applied at higher voltages
where VCESAT is less significant.
 Lower conduction losses at
higher currents.
 Higher switching losses favor
low frequency switching
applications.
 MOSFET
 Applied at lower voltages
where RDSON is very low.
 Lower conduction losses at
lower currents.
 Lower switching losses favor
high frequency switching
applications.
 Rule of Thumb:
 If the supply voltage is less than 30V, the output power is less than
250W or the switching frequency is greater than 20kHz, use a MOSFET.
 If the supply voltage is greater than 200V or the output power is
greater than 1kW, and the switching frequency is 20kHz or less, use an
IGBT.
 The lower switching losses and lower VCE(SAT) of modern IGBT’s will
allow IGBT’s to displace MOSFET’s in many HEV/EV applications,
especially if the 48V on-board supply is adopted.
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© 2012 Renesas Electronics America Inc. All rights reserved.
IGBT vs MOSFET Comparisons
Critical IGBT Specs
 RJH60F7DPQ





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VCES = 600V, IC = 90A
VCESAT @50A = 1.75V
tr = 81ns, tf = 74ns
VFD @20A = 2.1V
trr = 90ns
© 2012 Renesas Electronics America Inc. All rights reserved.
Critical MOSFET Specs
 RJK2061JPE





VDSS = 200V, ID = +/-40A
RDSON @20A = 0.075 Ohm
tr = 7ns, tf = 10ns
VFD @40A = 1.17V
trr = 155ns
IGBT vs MOSFET Comparisons
 Description of system used for calculations
 48V on-board supply.
 Air-conditioning compressor powered by a
2.17HP, 3-phase PMSM motor.
 Max cooling: 5530 BTU/hr = 0.46 ton.
 Max motor phase current: 56APEAK / 40ARMS.
 20kHz sinusoidal PWM.
IGBT losses per half/bridge
 IGBT Conduction Loss = 56.0W
 IGBT Switching Loss
 EON = 0.218mJ
 EOFF = 0.120mJ
 PSW = (EON + EOFF) * 20000 = 6.76W
 Diode Conduction Loss = 16.8W
 Diode Switching Loss = 2.42W
 Total Power Loss = 81.98W
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MOSFET losses per half/bridge
 MOSFET Conduction Loss = 114.0W
 MOSFET Switching Loss
 EON = 0.019mJ
 EOFF = 0.016mJ
 PSW = (EON + EOFF) * 20000 = 0.70W
 Diode Conduction Loss = 2.34W
 Diode Switching Loss = 4.17W
 Total Power Loss = 121.21W
HEV/EV Applications
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© 2012 Renesas Electronics America Inc. All rights reserved.
HEV/EV Applications
 In an HEV/EV, many functions that run directly from engine
power in a conventional auto must now run from battery
power.
 Transmission oil pump (hydraulic pressure for the actuators).
 A/C compressor.
 Cooling fan (still needed for the A/C condenser coil, battery
cooling and traction drive inverter cooling).
 Coolant pump.
 Power steering.
 These are higher power applications that might better use
IGBT’s, especially the A/C compressor and power steering.
 Particularly for EV’s, the trend is to run these applications
directly from the traction drive battery. This is more
efficient and the higher voltage favors the use of IGBT’s.
 Traction drive inverters will always use IGBT’s.
 Low power body applications generally will use MOSFET’s.
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© 2012 Renesas Electronics America Inc. All rights reserved.
HEV/EV Applications
 Many HEV/EV body applications are switching to PMSM motors for
improved reliability (no brushes).
 Such applications often can use 6-step trapezoidal commutation, in which
one phase is driven (PWM), one phase is always grounded and one phase
is always open.
 For IGBT switches, it truly is necessary to generate PWM signals only for
the high-side switch. The low-side switch should remain off during PWM.
STEP 1
STEP 2
STEP 3
1 2 3 4 5 6
STEP 4
STEP 5
STEP 6
• Digital outputs low for switch on.
• Analog trace – Phase A current.
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Conclusion
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© 2012 Renesas Electronics America Inc. All rights reserved.
Conclusion
 The Trench Gate and Field Stop technologies used in the
newer IGBT transistors are allowing IGBT’s to displace
MOSFET’s in many HEV/EV applications.
 The move to a 48V on-board supply makes IGBT’s much
more attractive.
 When performing the system design on a new HEV/EV
application, it makes sense to perform power loss
calculations for both types of transistor.
 In an increasing percentage of applications, it will be found
that IGBT’s offer a more efficient, lower cost solution.
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© 2012 Renesas Electronics America Inc. All rights reserved.
Questions?
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© 2012 Renesas Electronics America Inc. All rights reserved.
‘Enabling The Smart Society’
 Challenge:
Improve efficiency of HEV/EV automobiles.
 Solution:
Lower inverter losses by replacing MOSFET’s with IGBT’s in
high-current applications.
 Do you agree that this solution is viable?
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© 2012 Renesas Electronics America Inc. All rights reserved.
Renesas Electronics America Inc.
© 2012 Renesas Electronics America Inc. All rights reserved.