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AN-9742
Device Selection Guide for Half-Bridge Welding Machine
(IGBT & Diode)
Summary
Duty Cycle of a Welding Machine
Various topologies; including two SW-forward, half-bridge
and full-bridge, have been used for low-voltage / highcurrent DC-ARC welding machines for system minimization
and efficiency improvement. Of these topologies, halfbridge is the most commonly used for small form factor, less
than 230A capacity welding machines. Compared to fullbridge topology with the same power rating, half-bridge
requires more transformer wiring and higher current
capacity of inverter; but requires fewer power devices.
Taking a Fairchild evaluation board as the example, this
article presents a device selection guide for a half-bridge
welding machine application.
In the welding industry; duty cycle refers to the minutes out
of a 10-minute period a welder can be operated at maximum
rated output without overheating or burning up the power
source. For instance, a 140A welder with a 60% duty cycle
must be “rested” for at least 4 minutes after 6 minutes of
continuous welding at maximum rated output current 140A.
Allowable Duty Cycle
If actual current in use is smaller than a rated output current,
the welder internal heating decreases. The welder then can
be used at a higher rate than the specified duty cycle. Its
allowable duty cycle can be calculated as:
2
Description of Welding Machine
 rated output current 
 × duty cycle of welding machine
= 
 using output current 
Generally, based on the type of welding machine, the output
voltage can be calculated as shown in Table 1.
For example, since only 80A to 130A current would be
required to weld a 3.2 welding rod, a 140A welder with a
60% duty cycle can operate for a longer time for this
application. Assuming 100A is used to weld a 3.2 welding
rod, actual duty cycle is more than 78.4%.
Table 1.
Welding Machine Output Voltage
Welding
Machine
Output Voltage
Example
CO2
0.04•IAC+15
0.04•200A+15=23V
TIG
0.04•IAC+10
0.04•200A+10=18V
DC ARC
0.04•IAC+20
0.04•200A+20=28V
Table 2.
(1)
Besides the actual output current, the temperature also
affects the allowable duty cycle of a welding machine.
Do NOT overheat welder machines.
Feasible Welding Materials by Welding Machine
Welding Machine
Gas
Welding Type Steel
CO2
CO2
Mild, High Tensile
MIG
He + Ar
Aluminum, SUS, Aluminum Alloy
MAG
Sheet Metal, Low Alloy, High Tensile
DC-TIG
Stainless, Mild, Copper Alloy, Nickel Alloy, Titanium Alloy, Low Alloy
AC-TIG
Aluminum Alloy, Magnesium Alloy, Bass
Mixed TIG
Light Alloy, Clad Plate
DC-ARC
Steel, Nonferrous Metals
AC-ARC
Aluminum
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
www.fairchildsemi.com
AN-9742
APPLICATION NOTE
Fairchild DC-ARC Welding Machine Evaluation Board
Input Voltage and Frequency: 220VAC 60Hz
Evaluation Board Features
Output Voltage (VOUT) and Output Current (IWEL):
26VDC, 140A
Input Stage: 50A Bridge Diode (600V, 50A, SquareBridge Type)
Efficiency: > 80%
Input Filter Stage: Designed Under Consideration of
Conductive Noise and Radiation Noise
Idle Power: < 4W
Switching Frequency: 20KHz
Figure 2 shows the main block diagram of the welding
machine evaluation board. The output current and output
voltage of the DC-ARC welding machine evaluation board
are 26V and 140A, which constitutes a 3kW-class welding
machine. Various Fairchild Semiconductor components are
used to meet the design requirements. The switching
frequency of the machine is 20KHz. Due to their size; the
transformer and inductor are installed beside the board. An
air fan is attached for cooling.
Controller: PIC16F716 (8-Bit ADC and 10-Bit PWM)
Inverter Stage: FGH40N60SMD (within Co-Pak Diode)
Single or Parallel
Output Rectifier: FFA60UP30DN * Six Units (Three
Ultra-Fast Diode in Parallel)
Gate Driver: Opto-Coupler for the Isolation between
Switching Devices and Controller Dual Power Supply
+15V, -5V for IGBT Gate Voltage
AUX Power Supply: Lower Standby Consumption Green
Integrated PWM IC
Figure 1. Evaluation Board
Figure 2. Main Block Diagram
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
www.fairchildsemi.com
2
AN-9742
APPLICATION NOTE
Half-Bridge Inverter Design
IGBT Selection for Welding Machine
The turn ratio of the primary and secondary of the
transformer in a half-bridge topology can be obtained from
the equation:
Among various power switching components, Insulated Gate
Bipolar Transistor (IGBT) is the most suitable device for
welding machines thanking for its high current handling
capability and high switching speed. IGBT is a voltagecontrolled power transistor, similar to the power MOSFET
in operation and construction. This device offers superior
performance to the bipolar-transistors. It is the most costeffective solution for high power and wide frequency-range
applications. Table 3 shows the characteristics comparison
of IGBT with BJT and MOSFET.
N1 =
N1 =
VIN ( MIN ) × DMAX
4 × B × Ae ∗ f SW
(VO + VF + VI ) × N1
DMAX × VIN ( MIN )
(2)
(3)
where VI = VS, IWEL = output current, Id1 & Id2 = diode
current (output high side & output low side).
Table 3.
Output voltage under no load condition is given by:
Vnolaod =
(VO + VF = VI )
DMAX
(4)
where:
VO=output voltage;
VF=diode drop voltage; and
VI=inductor voltage drop.
Transformer’s primary and secondary current can be
obtained by:
I1rms =
N2
× IWEL ×
N1
1
I 2rms = × IWEL ×
2
(2 × DMAX )
(5)
(1 + 2 × DMAX )
(6)
N2
× IWEL
N1
(7)
Output rectifier diode voltage and current:
Vr =
N2
× VIN ( MAX ) , IWEL = I d12 + I d 2 2
N1
Features
BJT
MOSFETS
IGBT
Drive Method
Current
Voltage
Voltage
Drive Circuit
Complex
Simple
Simple
Input Impedance
Low
High
High
Drive Power
High
Low
Low
Switching Speed
Slow(µs)
Fast(ns)
Middle
Operating
Frequency
Low
Fast
(less than 1MHz)
Middle
S.O.A
Narrow
Wide
Wide
Saturation
Voltage
Low
High
Low
Power losses of an IGBT include conduction loss and
switching loss. The conduction loss is determined by
IGBT’s Vce(sat) value and the duty rate. The switching loss is
determined by turn-on and turn-off action during IGBT’s
switching transient. For IGBTs, there are technical trade-off
characteristics between the Vce(sat) and the switching loss. If
Vce(sat) is high, switching loss becomes low and vice versa.
Therefore, the designer should select an IGBT based on the
system configuration and its switching frequency. The total
loss of an IGBT can be expressed as:
Current running through the IGBT and secondary-side
rectifier diode can be calculated by:
IGBT Current : I D =
Device Characteristics Comparison
(8)
Total 1 Pulse Switching
Switching
Conduction Loss
=
X
+
(9)
Loss Loss (EON + EOFF) Frequency
(VCS(SAT) X IC X Duty)
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
www.fairchildsemi.com
3
AN-9742
APPLICATION NOTE
Figure 3 curves show the characteristics comparison
between PT IGBT and field-stop IGBT. PT IGBT has NTC
temperature characteristic: as temperature rises, Vce(sat)
decreases. Field-stop IGBT has PTC temperature
characteristic: as temperature rises, Vce(sat) increases.
Therefore, PT IGBT with NTC characteristic is more
suitable for the application where IGBT is operated solely.
However, if parallel operation of IGBTs is required for
current sharing, field-stop IGBT with PTC characteristic
would be more appropriate.
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
70
Collector Current, Ic[A]
2.0
Total Switching Loss[Eon+Eoff], Ets[mJ]
80
The following figures show that the switching loss becomes
the dominant factor over conduction loss in 25kHz and
above switching frequency area.
60
Tc=25deg.C
50
Vge=15V
1.5
Tc=25deg.C
Tc=125deg.C
1.0
0.5
Test Condition :
Vcc=400V, Rg=10 ohm, Vge=15V
0.0
10
40
20
30
40
Collector Current, Ic[A]
30
Figure 5. Total Switching Loss Ets
vs. Collector Current IC
20
10
250
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Total power loss of IGBT, Pd [W]
0.0
Collector-Emitter Voltage, Vce(sat)[V]
Figure 3. HGTG20N60A4D(PT) vs. FGH40N60UFD/SFD
(Field-Stop Gen1)
80
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
70
Collector Current, Ic[A]
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
60
Tc=125deg.C
Vge=15V
50
200
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
s
los
er
w
po
Vcc=400V, Rg=10 ohm,
tal
150 Vge=15V, Ic=40A, Tc=125deg.C To
Test Condition :
100
ing
itch
Sw
50
E
n+
Eo
[
s
los
]
off
Conduction loss
0
20.0k
40
40.0k
60.0k
80.0k
100.0k
Switching Frequency, Fsw[KHz]
30
Figure 6. Total Power Loss of IGBT Pd
vs. Switching Frequency
20
The gate resistor is also very critical to the switching loss.
High gate resistance results in high switching loss. On the
other hand, high gate resistance improves EMI performance
as the di/dt is lower during the switching transient. A
properly selected gate resistor should minimize the
switching loss without sacrificing system EMI performance.
10
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Collector-Emitter Voltage, Vce(sat)[V]
Figure 4. FGH40N60SMD (Field-Stop Gen2)
Reduction of conduction loss and total device cost with
better thermal performance would be the advantage of the
parallel operation of IGBTs. However, for such kind
application, the following must be considered:
Using high-temperature PTC characteristic IGBT
Using gate resistor with ≤1% tolerance for each IGBT
Proper gate PCB layout for symmetrical current paths
Identical heat sink size and airflow for each IGBT
Same threshold voltage and saturation voltage
characteristics
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
www.fairchildsemi.com
4
AN-9742
APPLICATION NOTE
Below are the IGBT turn-off characteristics measurements
with JIG testing. Under the same conditions, FS Planar
Gen2 IGBT FGH40N60SMD shows faster switching
characteristic, lower Vce(sat), and tremendously lower turn-off
loss compared to previous technology devices - PT and FS
Planar Gen1 IGBT.
Figure 9 and Figure 10 show the IGBT operation waveforms
of the evaluation board with R-load and welding load. These
waveforms reveal that welding load consumes three times
the current that R-load consumes. Therefore, it is important
to select IGBT with suitable Icm parameter to avoid
saturation at peak-current condition.
1.0
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
Switching Loss, Eoff[mJ]
0.8
Tc=25deg.C
Tc=125deg.C
0.6
0.4
Test Condition :
Vcc=400V, Ic=40A, Vge=15V
0.2
5
10
15
20
25
30
Gate Resistance, Rg[ohm]
Figure 9. R-Load Test at IOUT=14A
Figure 7. Turn-Off Loss EO vs. Gate Resistance Rg
16
Switching loss, Eoff / A[uJ]
Tc=25deg.C
FGH40N60UFD
12
HGTG20N60A4D
FGH40N60SFD
FGH40N60SMD
8
1.6
1.8
2.0
2.2
2.4
Collector-Emitter Voltage, Vce(sat)[V]
Figure 10. Welding-Load Test at 3.2 Pie Welding Rod
Figure 8. Turn-Off Loss EOFF vs. Collector-Emitter
Vce(sat)
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
www.fairchildsemi.com
5
AN-9742
APPLICATION NOTE
Figure 11 through Figure 16 show turn-off switching loss
EOFF measurement with welding load and R-load. Due to the
leakage inductance and capacitor element, there is huge
difference in EOFF measurement compared with the JIG test
result. The EOFF of FGH40N60SMD shows the lowest loss
from the test.
Figure 11. EOFF Comparison Under
R-Load (FGH40N60SMD)
Figure 12. EOFF Comparison Under
R-Load (FGH40N60UFD)
Figure 13. EOFF Comparison Under
R-Load (FGH40N60SFD)
Figure 14. EOFF Comparison Under
Welding Load (FGH40N60SMD)
Figure 15. EOFF Comparison Under
Welding Load (FGH40N60UFD)
Figure 16. EOFF Comparison Under
Welding Load (FGH40N60SFD)
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
www.fairchildsemi.com
6
AN-9742
APPLICATION NOTE
Rectifier Diode for Welding Machine
Qrr =
Fairchild Semiconductor provides five kinds of diodes that
cater to different applications. Diodes with lower Vf, Irr, and
Trr characteristics are ideal for welding applications;
however, the common P_N theory dictates that the lower the
Vf, the longer the Trr and vice versa. A designer chooses a
diode with a trade-off point where Vf and Trr benefit the
system efficiency the most. The following figures show
performance comparisons for 600V/8A diodes from each
Fairchild Semiconductor diode technology.
2.6
2.4
Stealth
2.2
Hyperfast2
VF [V]
The figures below show the performance of diodes used in
single and parallel configuration. Although the reverse
recovery loss increases, Vf is reduced with parallelized
diodes and better thermal performance can be expected.
Designer caution is required for parallel diode application to
ensure that the air flow does not cause unbalanced current
conditions, as the Vf of diode tends to decrease when the
temperature rises.
Ulrafast
Hyperfast
Hyperfast2
Stealth
Stealth2
Stealth2
Hyperfast
2.0
(10)
Generally, the rectifier diode of welding machine has higher
conduction loss than reverse recovery loss. Therefore, the
diode VF value is more critical for a welding application.
For this reason, ultra-fast diode FFA60UP30DN (30A dual
diode) is used for this evaluation board. Three diodes are
used in parallel for each tap of transformer to lower the VF.
FCS Rectifier Diode Vf vs Qrr, 600V 8A
2.8
1
× I rr × t rr
2
Tc=25deg.C
1.8
Diode I-V charateristic
100
1.6
Tc=25deg.C
Tc=125deg.C
Ultrafast
1.4
80
IF, Forward Current [A]
1.2
1.0
0
20
40
60
80
Qrr [nC]
Figure 17. VF vs. Qrr Trade-Off
FSC Rectifier performance @ 600V, 8A
10
Ultrafast
Hyperfast
Hyperfast2
Stealth
Stealth2
Tc=125deg.C
8
6
4
IF [A]
2
60
40
FFA60UP30DN-Dual
20
FFA60UP30DN-single
0
0.0
0
0.6
1.2
1.8
VF, Forward Voltage [V]
-2
-4
Figure 20. Diode I-V Characteristic
-6
-8
FFA60UP30DN Qrr charateristic
-10
360
-12
-80.0n
-40.0n
0.0
40.0n
80.0n
120.0n
VR = 150V
IF = 30A
Single
Dual
160.0n
Stored Recovery charge Qrr [nC]
Time [sec]
Figure 18. Reverse Recovery Performance
300
Tc=125deg.C
240
180
120
60
Tc=25deg.C
0
100
200
300
400
500
di/dt [ A/us]
Figure 21. Stored Recovery Charge Qrr vs.
Diode Current Slop di/dt
Figure 19. Test Circuit and Waveforms
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
www.fairchildsemi.com
7
AN-9742
APPLICATION NOTE
Figure 22 shows the diode switching loss when the board is
operating at 20KHz. The conduction loss is about 336µJ,
while the reverse recovery loss is only about 4µJ.
Figure 24. UIS Test Circuit
Figure 22. Diode Conduction Loss During Welding
Figure 25. FFA60UP30DN Immunity Capability
Blocking Capacitor
For half-bridge topology; if the two series DC bank
capacitors or the turn-on time of IGBTs are not matched,
DC flux occurs in the transformer. The accumulated DC flux
eventually drives transformer into saturation. The IGBTs
can be destroyed by sharply increased current due to the
saturated transformer. To block the DC flux in the
transformer core, a small DC blocking capacitor is placed in
series with the transformer primary. The value of the DC
blocking capacitor is given by:
Figure 23. Diode Reverse Recovery Loss
During Welding
Cblocking =
Avalanche occurs in a diode with sudden current increase
when the voltage across a diode exceeds the specified Vr
value. Here, the area (Vr(AVL)*Isa) that diode does not fail is
called avalanche energy and the equation is:
1
Vr ( AVL )
]
EAVL = × L × Isa 2 × [
2
(Vr ( AVL ) − VDD)
D max× ID
∆VP × Fsw
(12)
where ∆VP is the permissible droop in primary voltage due
to the DC blocking capacitor.
Below is the waveform of the transformer primary current.
The current abruptly rise due to the saturated transformer
caused by DC bias.
(11)
∴ Q1 = IGBT ( BV ces ) > DUT (Vr ( AVL ))
Avalanche energy is occurred by the second output inductor,
as shown in the equation. The immunity capability is
proportional to the inductance. The inductance of a welding
machine is generally designed as small value as several µH,
and diode immunity capability value becomes an important
factor for choosing a device.
Avalanche can occur in the secondary-side rectifier of a
welding machine; especially when the welding work is
completed and the reverse pass occurs by inductor.
Immunity capability is measured using a circuit as shown in
Figure 24 with the graph in Figure 25 showing avalanche
energy test result waveform.
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
Figure 26. IGBT Saturation Current
www.fairchildsemi.com
8
AN-9742
APPLICATION NOTE
Figure 27. Zoom of IGBT Saturation Current
Figure 28. PWM Convert 40KHz to 20KHz
Power Supply Structure and Design
MOSFET integrated IC FSMG0465R is used for power
supply. Its simple peripheral circuit and 66KHz switching
frequency reduce the PCB and transformer size. In addition,
the efficiency of power has been maximized by the
minimization of idling power that can be achieved from low
power consumption in Standby Mode (<1W at 230VAC input
at 0.5W load). There are transformer type and SMPS type
for the substitute power supply. SMPS type, compared to
linear transformer type, has stable output power over the
influence of input serge, sag, and noise; and minimal design
of size and weight is possible. In addition, transformer type
has a fixed input voltage, whereas SMPS has a wide input
voltage range of 80VAC~264VAC, which can be used for free
voltage welding machine without additional operation.
However, it is necessary to consider counter measures for
noise as the switching noise may affect main inverter. For
further information about Fairchild Power Switches
(FPS™), refer to the application note AN-4150 found at:
http://www.fairchildsemi.com/an/AN/AN-4150.pdf.
Gate Driver Design
A transformer, opto-coupler, or HVIC can be used for a gate
driver. Necessary supply voltages for different gate drivers
are listed as:
HVIC Driver: +15V, 0V (High and Low Gate),
+ 24V, 0V (Output Detect), +5V, 0V (Controller)
Otpo-Coupler Driver : +15V, 0V, -5V (High-Side Gate),
+15V, 0V, -5V (Low-Side Gate), +24V, 0V (Output Detect),
+5V, 0V (Controller)
Pulse Transformer: +24V, 0V (Output Detect),
+5V, 0V (Controller)
The opto-coupler and transformer provide isolation between
the control circuit and IGBTs. However, a transformer may
cause half bridge cross-conduction due to the offset voltage
of gate-pulse dead-time stage. Through an by integrated
high-voltage MOSFET, the HVIC provides isolations
between the control circuit and the high-side IGBT. This
does not work with negative supply voltage. A negative
supply voltage is necessary for HVIC during a fast
commutation in a half-bridge topology to prevent dv/dt
shoot-through. The shoot-through is linked to a fast voltage
variation across one of the two IGBTs. A current flowing
through collector-emitter capacitor can bring the gate
voltage of an IGBT, when turned off, to rise due to Miller
effect and obtain a cross conduction into the leg.
Controller Design
The evaluation board uses PIC16f716 for the control
circuits. PIC16f716 controller consists of four ports of 8-bit
AD converter and one port PWM timer with 9-bit, 40KHz
resolution. To generate two PWM pulses from one PWM
signal, a D flip-flop and an AND gate are used to divide the
40KHz PWM into 20KHz PWM pulse (see Figure 28).
R2
+5V
R3
1k
C2
104
17
18
+5V
R19
330
RA0/AN0
C12
104
RA1/AN1
2
RB3
9
3
+5V
2
Temp
VR3
5k
+5V
3
2
1
+5V
C19 C20 C21 C22 C23
104 104 104 104 104
R6
1K
R11
MCLR/VPP
RB7
2
Temp
R8
C4
104
ZD!
1
RB6
1N4099
D5
RB5
2
10k
J2
Output
C5
104
RA3/AN3/VREF
RB4
R9
1k
1N4937
RB0/INT
2
1
LVD
7
8
4
1
C6
R10
1K
RB1
RB2
RA4/TOCKI
3
2
6
2
C15
104
7409
8
6
Gate1_1
5
4
gate1_2
3
3
2n3904d/ON
7474
C13
470P
-15V
+5V
R20
330
C9
22P
330
R12
330
R13
330
+15V
U6
2 PS2501
8
6
3
U4B
5
4
Q1
4
R18 1K
12
C16
104
Gate2_1
gate2_2
6
5
11
7409
R14
330
R15
330
R16
330
2n3904d/ON
-15V
C14
470P
10
6
3
G1
Cont+
PC1
PC817
105
Q
CLK Q
Q2
R17 1K
13
+5V
VR2
5k
D
1
GND
2
1
R7
1K
4
U3A
5
X1
20Mhz
15
C8
22P
560
U2A
U5
2 PS2501
16
5
J1
OSC2/CLKOUT
R4
36k R5
C3
104
Current Limit
TH
RA2/AN2
OSC1/CLKIN
J1
1
1
VR1
5k
BD1
+5V +5V +5V +5V +5V
4
14
C11
10uF/10V
C10
104
PRE
D4
1N4937
C1
22uF/10V
R1
10 ohm/3W
PIC16C711
C LR
D3
1N4937
U1
1
2
1
+5V
D2
1N4937
VD D
J3
CT
+15V
+5V
27k
D1
1N4937
G2
Cont-
RD1
SD
G3
PWR
Y1
WLD
RD2
ERR
C7
104
Figure 29. Controller Schematic
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
www.fairchildsemi.com
9
AN-9742
APPLICATION NOTE
ICG = dv/ dt × CCG
Q I CG = G CG × dV / dt
Vge = Rg × ICG
Figure 34. Opto-Driver Gate Waveform
Figure 30. Effect on dv/dt to VGE
DC Reactor Design
DC reactor helps stabilize arc current during welding
operation. As DC reactance grows, specter occurs smaller.
On the contrary, if the mobility of arc is lowered and the LDC
value gets too large, it is harder to create an arc. Therefore,
an appropriate reactor choice is necessary. If considering
VOPEN as output no-load voltage, VWEL and IWEL as rated
output voltage or current; the maximum LDC value can be
obtained from the equation:
: LDC ≤
Figure 31. Effect on dV/dt to Gate Wave
− R × tR
IWEL
In(1 −
× R)
Vopen
(13)
Based on the above considerations, an opto-coupler is used
for this welding machine evaluation board. Figure 32 and
Figure 33 present the gate waveforms captured with
different types of gate drivers. It is clear the opto-coupler is
the best choice for this welding application.
where R is the equivalent resistance of welding load and Tr
is the rising time of the output current from 0 to the rated
current. Once the maximum LDC value is obtained; the
optimum LDC value can be finalized through testing.
Figure 32. HVIC Gate Waveform
Figure 35. Soft-Start During Welding Operating
Figure 33. Transformer Gate Waveform
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
Figure 36. Welding Operating
www.fairchildsemi.com
10
AN-9742
APPLICATION NOTE
When to chose an IGBT, its Vce(sat), Eoff turn-off loss, gate
driver resistor, and Icm characteristics are the critical factors
that require a designer’s careful attention.
Conclusion
Better performance is expected for a DC-ARC welding
machine when the inverter devices are selected properly
based on the inverter topology and its switching frequency.
This article presents a power device selection guide for a
half-bridge welding machine application.
For the secondary -side rectifier diodes, it is important to
determine which is the dominant factor, Vf or reverse
recovery loss, based on system switching frequency. The
evaluation
board
uses
three
ultra-fast
diodes
(FFA60UP30DN) in parallel for each tap of the transformer
to lower the Vf and therefore the conduction loss.
References
[1]
Aspandiar, Raiyo, “Voids in Solder Joints,” SMTA Northwest Chapter Meeting, September 21, 2005,
Intel® Corporation.
[2] Bryant, Keith, “Investigating Voids,” Circuits Assembly, June 2004.
[3] Comley, David, et al, “The QFN: Smaller, Faster, and Less Expensive,” Chip Scale Review.com, August /
September 2002.
[4] Englemaier, Werner, “Voids in solder joints-reliability,” Global SMT & Package, December 2005.
[5] IPC Solder Products Value Council, “Round Robin Testing and Analysis of Lead Free Solder Pastes with Alloys of
Tin, Silver, and Copper,” 2005.
[6] IPC-A-610-D, “Acceptance of Electronic Assemblies,” February 2005.
[7] IPC J-STD-001D, “Requirements for Soldered Electrical and Electronic Assemblies.”
[8] IPC-SM-7525A, “Stencil Design Guidelines,” May 2000.
[9] JEDEC, JESD22-B102D, “Solderability,” VA, Sept. 2004.
[10] Syed, Ahmer, et al, “Board-Level Assembly and Reliability Considerations for QFN Type Packages,”
Amkor Technology, Inc., Chandler, AZ.
Related Resources
FGH40N60SMD — 600V, 40A Field Stop IGBT
FFA60UP30DN — 300V Ultrafast Recovery Power Rectifier
FSGM0465R — SMPS Power Switch, 4A, 650V (Green)
Appendix — Circuit Diagrams
C23
R6
10
102
+ BUS
Z1
FGH40N60SMD
ZD1
1N4744
BD1
C54
1uF M275V
1
4
+
-
1
C1
400V 560uF
RV3
20D431K
C2
400V 560uF
GBP5006
ZD3
1N4744
ZD6
1N4744
L6
GND2
FAN
2
R3
10/3W
ZD4
1N4733
10/3W
FGA60UP30DN
630V
Z4
FGA40N60SMD
ZD8
1N4744
ZD9
1N4733
R9
T1
1
Gate2
R8
D3
CT1
C61
R4
4.7k
ZD7
1N4733
R7
4.7k
C50
10uF 630V
Gate1
Z3
FGA40N60SMD
Gate2
RV1
20D431K
1
10/3W
GND1
3
LF1R
FILTER
C62
472M
R1
R2
4.7k
ZD2
1N4733
5
D7 FGA60UP30DN
6
3
2
RV2
20D431K
C55
472M
P11
1
Z2
FGA40N60SMD
Gate1
1
P3
1
L5
P10
JF3250G
4
L4
52uH
8
D16
C51
10uF 630V
R39
C24
10/3W
10
+ Output
FGA60UP30DN
TRANSFORMER CT
102
C52
10nF 630V
R5
4.7k
D17
- BUS
D18
D19
FGA60UP30DN
FGA60UP30DN
C53
10nF 630V
FGA60UP30DN
- Output
Figure 37. Main Circuit
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
www.fairchildsemi.com
11
AN-9742
APPLICATION NOTE
C209 102
R211 10
D203
T101
EER3940S
L1 10uH
+15v
9
MBRF10H100
C223
470uF 35V
1
C224
470uF 35V
10
R212
C208
3.3nF 630V
R207
43K/1W
3
R208
2
BD201
5D-9
LF201
30mH
+
-
C222
470uF 35V
L2 10uH
-15V
U201
6
R201
1M/1W
2KBP06M3N25
C211102
R21310
7
D205
FGM0465R
L3 10uH
1
Drain
15+v
Vstr
8
12
MBRF10H100
C203
400V 100uF
R203
150K
4
FB
D201
3
Vcc
2
AC220V N
PC1
Q201
2N2222
C205
33nF 100V
C217
470uF 35V
C218
470uF 35V
D206
L4 10uH
-15V
ZD201
1N4745A
1
C204 R205
47nF 1K
1K 2
14
2
R204
C220
470uF 35V
GND2
C212 102
1W 5
R209
100 ohm/0.5W
2
250V 2A
C219
470uF 35V
13
R210
R214 10
UF4004
1
C202
275Vac 100nF
1N4007
1k
R202
270K
1
3
C201
275Vac 100nF
4
GND
NTC
F201
C211
470uF 35V
MBRF10H100
NTC1
AC220V H
TNR
10D471k
GND1
C210
10 D204
102
11
D202
R206
75K
C206
100nF
MBRF10H100
C207
47uF 50V
R215
10
15
D38
1N4744
C213
D207102
L5
1
5v
4.9uH
MBRF10H100
C215
470uF 10V
16
XY
C216
1000uF 10V
gnd
4.7nF/1KV
R216
R219
1
4
620
2
3
3
1
R218
C214
18K
47nF
R220
8K
2
U202
TL431
8K
R217
1.2k
PC2 817
Figure 38. Auxiliary Power Supply
Figure 39. Controller
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS
HEREIN TO IMPROVE RELIABILITY, FUNCTION, OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE
APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS
PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS
WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION.
As used herein:
1.
Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, or (c) whose failure to perform
when properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to
result in significant injury to the user.
© 2011 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 9/9/11
2.
A critical component is any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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