Download Optimizing 1200V IGBT Modules for High Frequency Applications

Optimizing 1200V IGBT Modules for High Frequency Applications
Eric R. Motto*, John F. Donlon*
Yoshikatsu Nagashima**
* Powerex Incorporated, Youngwood, Pennsylvania, USA
** Power Device Division, Mitsubishi Electric Corporation, Fukuoka, Japan
Abstract - This paper presents a new 1200V 5th generation
IGBT module that has been optimized specifically for
applications requiring hard turn-on switching and
operating frequencies of 15KHz to 30KHz. The module
also features reduced turn-off losses compared to
standard industrial devices making it suitable pure hard
switching applications requiring high PWM frequencies
such as sinusoidal output inverters for alternate energy
utility interface and high precision industrial motor
drives.
I. INTRODUCTION
The fundamental trade-off between turn-off switching loss
(ESW(off)) and on state voltage drop (VCE(sat)) in IGBT chip
design is well known. Standard industrial IGBT modules are
typically optimized for motor drive and similar applications
in which the carrier frequency is typically 10KHz or less. For
these applications conduction losses tend to dominate so the
IGBT chip is primarily optimized for low VCE(sat). Other
high power industrial applications such as medical, laser,
telecommunication and induction heating power supplies
often require higher operating frequencies to improve
performance and reduce the size of magnetic components. In
these higher frequency applications dynamic losses become
dominant and often limit the usable capability of the IGBT
module. In 2002 a high frequency optimized 5th generation
IGBT module was developed specifically for high frequency
power supply applications [1]. The IGBT turn-off loss of the
new device was reduced to about 25% of the standard module
by adjusting the minority carrier lifetime. Unfortunately, one
side effect of the carrier lifetime adjustment is increased
saturation voltage which causes larger static losses. In
addition, the free wheeling diode used in these devices was
optimized primarily for low switching noise. These “super
soft” recovery diodes exhibit a recovery current tail that
produces a relatively large recovery loss (Err). The diode
recovery tail current also contributes to increased turn-on
losses in the opposing arm IGBT in hard switching
applications. As a result, the high frequency optimized
modules are most effective in applications having a soft turnon such that the turn-on and free wheel diode recovery losses
are minimized by the external circuit design and operation.
In high frequency applications requiring a hard turn-on the
high frequency optimized device offers only a modest
reduction in dynamic losses (ESW(on)+ESW(off)+Err) and because
of its increased static losses the total loss may be unimproved
or even larger than the standard speed module. This paper
presents a new high frequency optimized industrial IGBT
module designed for applications requiring hard turn-on.
II. DEVICE DESIGN AND CHARACTERISTICS
In the design of an IGBT chip it is possible to trade VCE(sat)
for lower switching losses by adjusting the minority carrier
lifetime. Figure 1 shows this trade-off for the 5th generation
Figure 1: EOFF -vs- VCE(sat) Trade-Off for 1200V, 200A module (Tj=125C)
30
EOFF (mJ)
25
Standard 5 th Generation Module
CM200DY -24NF
New
“NFM”
series
” series
New“NFM
20
15
High Frequency 5 th Generation Module
CM200DU -24NFH
10
5
0
1.6
1-4244-0714-1/07/$20.00 ©2007 IEEE.
2.6
3.6
Vce(sat)
1254
4.6
5.6
CSTBT chip. Standard industrial devices (NF-Series) are
optimized with low VCS(sat) and relatively high turn-off losses
while high frequency optimized devices (NFH-Series) have
very low turn-off losses and a somewhat higher VCE(sat).
Recognizing that the contribution of ESW(off) to total losses
will inevitably be smaller in applications having a hard turnon with substantial ESW(on) and Err losses leads to a somewhat
slower optimization point than the standard high frequency
device. The selected optimization for the new module (NFMSeries) is shown in figure 1. The new device has lower
ESW(OFF) than the standard speed device and lower VCE(sat) than
the high frequency optimized device. In addition, for hard
turn-on applications a new free wheeling diode was
developed to reduce the Err and ESW(ON) losses. The new
diode uses a shallow P-I-N junction structure formed using
epitaxial silicon wafer material to achieve fast recovery with
minimal tail current. A summary of the key characteristics of
Table 1: 300A, 1200V Module Characteristic Comparison (Tentetive Data)
Characteristic
Standard
CM300DY-24NF
Fast
New
CM300DU-24NFH CM300DC-24NFM
VCE(SAT) (V)
1.9
5.0
3.0
VEC (V)
2.1
2.4
1.8
ESW(ON) (mJ)
44
31
23
ESW(OFF) (mJ)
37
10
19
Err (mJ)
27
24
17
the former standard speed device (NF-Series), fast device
(NFH-Series) and the new NFM module is shown in table 1.
III. DEVICE PERFORMANCE
Figure 2 shows a typical resonant-mode switching circuit.
Figure 2: Resonant Mode Switching Circuit Operation
a. Resonant Switching with Hard Turn-Off
b. Resonant Switching with Hard Turn-On
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Figure 3: Loss Comparison for 300A, 1200V modules switching as shown in figure 2.
Standard
NF-Series
Standard
NF-Series
New
NFM-Series
Fast
NFH-Series
New
NFM-Series
Fast
NFH-Series
a. Resonant Switching with Hard Turn-Off
b. Resonant Switching with Hard Turn-On
Depending on the design and control technique this circuit
can be operated with hard turn-off or hard turn-on switching.
Figure 3 shows a comparison of losses between the standard
speed, high frequency and new device for both switching
modes at 30KHz. From this drawing it is clear that for the
case of soft turn-on the high frequency optimized device (NFH-
Series) has the lowest total losses while the new device (NFMSeries) has the lowest losses for the case of hard turn-on. The NFM
module has lower total losses under the hard turn-on case because its
conduction losses, turn-on loss and diode recovery losses are lower
than the NFH device. On the other hand, if a soft turn-on is used the
turn-off losses become the dominant loss component and the NFH
device provides the lowest loss.
Figure 4: Hard Switched Sinusoidal Output Inverter Losses
600A,1200V Module (Nominal Rating), IO=400ARMS, VBUS=600V, PF=0.8
1800
1600
Power Loss (W)
1400
1200
1000
800
Standard (NF-Series)
600
New (NFM-Series)
400
Fast (NFH-Series)
200
0
0
5
10
15
20
25
PW M fre que ncy (KHz)
1256
30
35
Figure 4 shows total losses versus PWM frequency for a
sinusoidal output inverter having both hard turn-on and hard turn-off
switching. In this figure it can be seen that new module becomes
the lowest loss device above about 12KHz switching frequency.
The former high frequency device (NFH-Series) is of little practical
use in this application because its low turn-off losses can not
compensate for its increased static losses.
IV. CONCLUSION
[13] E. Motto, et al., "Evaluating the Dynamic Performance
of High Current IGBT Modules", PCIM/PQ 1994
[14] E. Motto, "Protecting High Current IGBT Modules
From Over Current and Short Circuits", HFPC Conference
1995
[15] Eric R. Motto, et al., “New Process Technologies
Improve IGBT Module Efficiency”, IEEE Industry
Applications Society Conference 1995
[16] Eric R. Motto, “A New Low Inductance IGBT Module
Package”, PCIM Conference 1996
A new 1200V high frequency optimized CSTBT module
has been presented. The module features an optimized 5TH
generation CSTBT chip with lower Vce(sat) than
conventional high frequency types and lower switching losses
than standard speed devices. The new module also includes
an optimized epitaxial free wheeling diode to provide reduced
turn-on and recovery losses. The new module provides
reduced losses in high frequency applications having hard
turn-on switching conditions.
REFERENCES
[1] J. Yamada, et al., “A Fast Switching 1200V CSTBT”
IEEE Industry Applications Society Conference 2002
[2] H. Takahashi, et al., “Carrier Stored Trench-Gate Bipolar
Transistor (CSTBT) - A Novel Power Device for High
Voltage Application”, The 8th International Symposium on
Power Semiconductor Devices and ICs 1996
[3] E. Motto, et al., “Characteristics of a 1200V PT IGBT
With Trench Gate and Local Life Time Control”, IEEE
Industry Applications Society 1998
[4] H. Iwamoto, et al., “A New Punch Through IGBT Having
A New N-Buffer Layer”, IEEE Industry Applications Society
1999
[5] H. Nakamura, et al., “Wide cell pitch 1200V NPT CSTBTs
With Short Circuit Ruggedness”, International Symposium on
Power Semiconductor Devices and ICs 2001
[6] G. Majumdar, et al., "A New Generation High Speed Low
Loss IGBT Module", International Symposium on Power
Semiconductor Devices and ICs 1992
[7] J Yamashita, et al., "A Study on the Short Circuit
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[8] Powerex "IGBTMOD and IntellimodTM Application and
Technical Data Book" PUB# 9DB-100, March 1998
[9] Majumdar, et al., "Enhancing SOAs of IGBT Modules for
Hard Switching Applications", PCIM 1990
[10] Yamada, et. al., "Next Generation Power Module",
International Symposium on Power Semiconductor Devices
and ICs 1994
[11] M. Harada, et al., "600v Trench IGBT in Comparison
with Planar IGBT", International Symposium on Power
Semiconductor Devices and ICs 1994
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