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AN-9742
半桥焊机功率器件(IGBT与二极管)的选型指南
摘要
为了减小系统,提高效率,低压/大电流DC-ARC焊机中
使用了不同的拓扑结构,包括双开关正激、半桥和全桥
变换器;其中,在容量低于230A的焊机中,半桥变换器
由于其较小波形因数而被广泛使用。在额定功率下,与
全桥拓扑结构相比,半桥变换器需要更多的变压器绕线
和更大的逆变器电流容量,但是只需要较少的功率器
件。本文以飞兆半导体的评估板为例,给出了一种半桥
式焊机应用中器件选型指南。
焊机概述
一般地,可以根据焊机类型计算输出电压,如表1所
示。
Table 1. 焊机的输出电压
焊机 输出电压 范例
二氧化碳 0.04•IAC+15 0.04•200A+15=23V
钨极惰性气体
保护电弧焊 0.04•IAC+10 0.04•200A+10=18V
直流电弧 0.04•IAC+20 0.04•200A+20=28V
焊机的负载持续率
在焊接工业中,负载持续率是指在10分钟周期内,
保证未过热和电源未烧毁的情况下,焊机在最大额定输
出时的可运行分钟。比如,负载持续率为60%的140A的
焊机在以最大额定输出电流140A连续焊接6分钟后至少
需要休息4分钟。
允许的负载持续率
如果工作时的有效电流比额定输出电流小,焊机的
内部发热会降低。此时,焊机可以工作在比指定负载
持续率高的状态。它的允许负载持续率可以根据下式
计算:
machine weldingof cycleduty currentoutput using
currentoutput rated2
(1)
例如,由于焊接3.2的焊条时,只需要80A到130A的电
流,此时,负载持续率为60%的140A的焊机可以工作
更长。假设焊接3.2的焊条时的电流为100A,实际负载
持续率高于78.4%。
除了实际输出电流,温度也影响焊机的允许负载持续
率。不要使焊机过热。
Table 2. 焊机的可行焊接材料
焊机 气体 焊接类型钢
二氧化碳 二氧化碳 低碳,高张力
金属焊条惰性气体
(水下焊接) 氦+氩 铝,不锈钢,铝合金
熔化极活性气体保护焊 薄金属,低合金,高张力
直流钨极惰性气体保护焊 不锈,低碳,铜合金,镍合金,钛合金,低合金
交流钨极惰性气体保护焊 铝合金,镁合金,Bass
混合钨极惰性气体保护焊 轻合金,复合板
直流电弧 钢,有色金属
交流电弧 铝
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 2
飞兆半导体直流电弧焊机评估板
评估板特征
输入级:50A桥用二极管(600V/50A/方桥)
输入滤波级:设计时考虑到传导噪声和辐射噪
声
控制器:PIC16F716(8-位 ADC和10-位PWM)
逆变器电路:FGH40N60SMD(在Co-Pak二极
管内)单只或并联
输出整流器:FFA60UP30DN *6单元(三个超
快二极管并联)
门极驱动器:开关器件和控制器实施光电耦合
隔离,IGBT门极电压采用+15V、-5V双电源供
应
AUX电源供应:较低待机消耗的绿色集成PWM
芯片
输入电压和频率:220V VAC 60Hz
输出电压(VOUT)和输出电流(IWEL): 26VDC, 140A
效率:>80%
待机功率:< 4W
开关频率:20KHz
图2 给出了焊机评估板的主电路框图。DC-ARC焊机评
估板的输出电流和输出电压分别为26V和140A,构成了
3kW功率等级的焊机。焊机使用了一系列的飞兆半导体
器件完成设计要求。焊机的开关频率为20kHz。考虑到
尺寸,变压器和电感装在了电路板附近。还装有一个散
热用风扇。
Figure 1. 评估板
H
N
220VAC
Input
DC Link
Capacitor Half-Bridge Inverter
DC
Output~
~
+-
~
~
+-
Power Supply
N
Q
QSET
CLR
D
Bridge
Diode
Control
Output Rectifier
+
-
FSGM0465R
PIC16F716 (micro-controller)
40Khz20Khz
PWM
controller
Inverter Driver (Opto-Coupler)
EMI
Filter
Figure 2. 主框图
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 3
半桥逆变器设计
半桥拓扑结构中,变压器的初级与次级匝数比的计算公
式为:
4
)(
1
SWe
MAXMININ
fAB
DVN
(1)
)(
)(
11
MININMAX
IFO
VD
NVVVN
(2)
式中,VI 即 VS,IWEL为输出电流,Id1 与Id2为二极管电
流(输出高端和输出低端)。
空载条件下的输出电压为:
MAX
IFOnolaod
D
VVVV
(3)
式中,
VO为输出电压;
VF为二极管跌落电压;
VI为电感跌落电压。
变压器初级和次级电流的计算公式为:
MAXWELrms DIN
NI 2
1
21 (4)
MAXWELrms DII 212
12 (5)
流过IGBT和次级整流二极管的电流为:
WELIN
IGBT 1
2D
NI :Current (6)
输出整流二极管的电压和电流为:
22
21)( ,
1
2ddWELMAXINr IIIV
N
NV (7)
焊机用IGBT选型
在众多的功率开关器件中,绝缘栅双极晶体管
(IGBT)由于其大电流能力和高开关速度,成为了焊
机最合适的器件。IGBT与功率MOSFET在机理和构造
上相似,是一种电压控制型功率晶体管。该器件具有比
双极晶体管更优越的性能。由于可在大功率和较宽的频
率范围内应用,使之成为了最为经济的选择。表3给出
了IGBT和BJT、MOSFET的特性比较。
Table 3. 器件特性的比较
特点 BJT MOSFET IGBT
驱动方法 电流 电压 电压
驱动电路 复杂 简单 简单
输入阻抗 低 高 高
驱动功率 高 低 低
开关速度 慢(µs) 快(ns) 中等
工作频率 低 快(低于1MHz) 中等
安全工作区 窄 宽 宽
饱和电压 低 高 低
IGBT的功率损耗包括导通损耗和开关损耗。导通损耗
取决于IGBT的Vce(sat)值和占空比。开关损耗取决于IGBT
开关瞬态时的开通和关断行为。IGBT在Vce(sat)具有特定
的平衡特性。当Vce(sat)高时,开关损耗低;反过来亦
然。因此,设计者应该基于系统结构和其开关频率选择
IGBT。IGBT的总损耗可以描述为:
总损
耗 =
单脉冲开关损耗
(EON + EOFF) X 开关频率 +
通态损耗(VCS(SAT) X
IC X 占空比) (8)
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 4
图3中的曲线给出了传统型(PT) IGBT和场截止型
(field-stop)IGBT的特性对比。PT IGBT具有负温度系
数特性:当温度升高时,Vce(sat)减小。Field-stop IGBT具
有正温度系数特性:当温度升高时,Vce(sat)增大。因
此,当IGBT单独使用时,具有负温度系数特性的PT
IGBT更加合适。当使用IGBT并联分流时,具有正温度
系数特性的Field-stop IGBT将更加合适。
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
0
10
20
30
40
50
60
70
80
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
Co
lle
cto
r C
urr
en
t, I
c[A
]
Collector-Emitter Voltage, Vce(sat)[V]
Tc=25deg.C
Vge=15V
Figure 3. HGTG20N60A4D(PT) vs. FGH40N60UFD/SFD (场
截止1代)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
0
10
20
30
40
50
60
70
80
Co
lle
cto
r C
urr
en
t, I
c[A
]
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
Tc=125deg.C
Vge=15V
Collector-Emitter Voltage, Vce(sat)[V]
Figure 4. FGH40N60SMD (场截止2代)
鉴于具有更好的热力性能,减少导通损耗和降低整体器
件成本,便于IGBT并联工作。无论如何,在这种应用
中需要考虑以下几点:
使用耐高温、正温度系数特性的IGBT
确保IGBT门极电阻误差≤1%
合适的门极PCB布局,确保获得对称的电流路径
IGBT具有完全相同的散热器规格和风扇
相同的阀值电压与饱和电压特性
下图给出了在25kHz以及更高的开关频率范围时,开关
损耗超过导通损耗,成为主要损耗因素。
10 20 30 40
0.0
0.5
1.0
1.5
2.0
Test Condition :
Vcc=400V, Rg=10 ohm, Vge=15V
Tc=25deg.C
Tc=125deg.C
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
To
tal S
wit
ch
ing
Lo
ss
[Eo
n+
Eo
ff],
Ets
[mJ
]
Collector Current, Ic[A]
Figure 5. 总开关损耗Ets vs. 集电极电流IC
20.0k 40.0k 60.0k 80.0k 100.0k
0
50
100
150
200
250
Test Condition :
Vcc=400V, Rg=10 ohm,
Vge=15V, Ic=40A, Tc=125deg.C
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4DT
ota
l p
ow
er
los
s o
f IG
BT
, P
d [
W]
Switching Frequency, Fsw[KHz]
Conduction loss
Switching lo
ss[ Eon+ Eoff]
Total power lo
ss
Figure 6. IGBT的总功率损耗Pd vs. 开关频率
对于开关损耗,门极电阻是非常关键的。较大门极电阻
会导致较高开关损耗。另一方面,由于较大门极电阻时
开关瞬态di/dt更低,故可提高EMI性能。适当的门极电
阻应该在满足系统EMI性能要求的前提下,具有最小的
开关损耗。
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 5
下图给出了JIG测试中测得的IGBT关断特性。在相同的
条件下,比较采用先前技术的器件——PT和FS平面一
代IGBT 相比,FS平面二代IGBT FGH40N60SMD表现出
了更快的开关特性、更低的Vce(sat)和惊奇的低关断损
耗。
5 10 15 20 25 30
0.2
0.4
0.6
0.8
1.0
Test Condition :
Vcc=400V, Ic=40A, Vge=15V
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
Tc=25deg.C
Tc=125deg.C
Sw
itc
hin
g L
os
s, E
off[m
J]
Gate Resistance, Rg[ohm]
Figure 7. 关断损耗EO vs. 门极电阻Rg
1.6 1.8 2.0 2.2 2.4
8
12
16
Tc=25deg.C
FGH40N60SMDFGH40N60SFD
HGTG20N60A4D
FGH40N60UFD
Collector-Emitter Voltage, Vce(sat)[V]
Sw
itc
hin
g lo
ss
, E
off / A
[uJ
]
Figure 8. 关断损耗 EOFF vs. 集电极-发射极电压 Vce(sat)
图9和图10给出了评估板在电阻负载和焊接负载下得
IGBT工作波形。这些波形说明,焊接负载消耗的电流
为电阻负载的3倍。因此,需要选择具有合适参数Icm的
IGBT,避免在峰值电流条件下出现饱和,这点是非常
重要的。
Vge_H : 5V/div
ID : 20A/div
Vge_L : 5V/div
Vce_L : 100V/div
4µs/div
Figure 9. 在IOUT=14A下的电阻负载测试
Vge_H : 5V/div
ID : 50A/div
Vge_L : 5V/div
Vce_L : 100V/div
4µs/div
Figure 10. 3.2 Pie型焊条下的焊接负载测试 Pie型
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 6
图11到图16给出了焊机负载和电阻负载下测得的关断开
关损耗EOFF。考虑到漏感和电容的因素,与JIG测试结果
相比,EOFF的测量结果具有很大的不同。根据测试,
FGH40N60SMD的EOFF表现出了最低的损耗。
Eoff: 5.03mJ
ID : 20A/div
Vge_L : 5V/div
Vce_L : 100V/div
400ns/div
Eoff: 5.476mJ
ID : 20A/div
Vge_L : 5V/div
Vce_L : 100V/div
400ns/div
Eoff: 5.927mJ
ID : 20A/div
Vge_L : 5V/div
Vce_L : 100V/div
400ns/div
Figure 11. 电阻负载下的EOFF的比较
(FGH40N60SMD)
Figure 12. 电阻负载下的EOFF的比较
(FGH40N60UFD)
Figure 13. 电阻负载下的EOFF的比较
(FGH40N60SFD)
Eoff: 36.13mJ
ID : 50A/div
Vge_L : 5V/div
Vce_L : 100V/div
1us/div
Eoff: 37.81mJ
ID : 50A/div
Vge_L : 5V/div
Vce_L : 100V/div
1us/div
Eoff: 42.88mJ
ID : 50A/div
Vge_L : 5V/div
Vce_L : 100V/div
1us/div
Figure 14. 焊接负载下的EOFF的比较
(FGH40N60SMD)
Figure 15. 焊接负载下的EOFF的比较
(FGH40N60UFD)
Figure 16. 焊接负载下的EOFF的比较
(FGH40N60SFD)
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 7
焊机用整流二极管
飞兆半导体为不同的应用提供五种二极管。低Vf、Irr和
Trr特性的二极管为焊机应用中最理想选择;但是一般的
P_N理论指出,Vf越低,Trr越长,反之亦然。设计者选
择二极管时,应找到Vf、Trr的平衡点,来使得系统效率
最大。下图给出了每一种飞兆半导体二极管技术的
600V/8A二极管的性能比较。
0 20 40 60 80
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
Stealth2 Ulrafast
Hyperfast
Hyperfast2
Stealth
Stealth2
Stealth
Hyperfast2Hyperfast
Ultrafast
Tc=25deg.C
VF
[V
]
Qrr [nC]
FCS Rectifier Diode Vf vs Qrr, 600V 8A
Figure 17. VF vs. Qrr 权衡考虑
-80.0n -40.0n 0.0 40.0n 80.0n 120.0n 160.0n-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
Tc=125deg.C
IF [
A]
Time [sec]
Ultrafast
Hyperfast
Hyperfast2
Stealth
Stealth2
FSC Rectifier performance @ 600V, 8A
Figure 18. 反向恢复特性
L
RG
Vge
DUTCURRENT
SENSE
IGBT
Test Circuit and Waveforms
VDD
Figure 19. 测试电路和波形
rrrrrr tIQ 2
1 (9)
一般的,焊机的整流二极管的导通损耗高于反向恢复损
耗。因此,焊机应用中,二极管的VF值更加关键。鉴于
此,评估板使用了超快二极管FFA60UP30DN(30A双
二极管)。变压器的每个抽头并联三个二极管来降低
VF。
下图给出了单个使用和并联使用的二极管的特性。尽管
反向恢复损耗有所增加,并联使用可以获得较低的VF,
并且具有更好的散热性能。对于二极管并联应用,鉴于
温度升高时,二极管的VF会降低,因此设计者应该确保
气流不会引起电流不均衡条件。
0.0 0.6 1.2 1.8
0
20
40
60
80
100
Tc=25deg.C
Tc=125deg.C
VF, Forward Voltage [V]
FFA60UP30DN-Dual
FFA60UP30DN-single
IF, F
orw
ard
Cu
rre
nt
[A]
Diode I-V charateristic
Figure 20. 二极管I-V特性曲线
100 200 300 400 500
0
60
120
180
240
300
360FFA60UP30DN Qrr charateristic
Tc=25deg.C
Tc=125deg.C
Sto
red
Re
co
ve
ry c
ha
rge
Qrr [
nC
]
di/dt [ A/us]
VR = 150V
IF = 30A
Single
Dual
Figure 21. 存储恢复电荷 Qrr vs.
二极管电流斜率 di/dt
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 8
图22给出了电路板工作频率为20kHz时的二极管开关损耗。通
态损耗约为336µJ,反向恢复损耗仅为4µJ左右。
10µs/div
IWEL: 50A/div
V1 : 2V/div
Econ=368.8uJ
VD1 : 10A/div
Figure 22. 焊接过程中的二极管导通损耗
200ns/div
IWEL: 50A/div
V1 : 50V/div
Econ=3.908uJ
VD1 : 1A/div
Figure 23. 焊接过程中的二极管反向恢复损耗
当某一二极管反向电压超过指定Vr值时,二极管将发生
雪崩现象,电流急剧增加。二极管并未失效的区域
(Vr(AVL)*Isa)称为雪崩能量,其方程为:
])(
[2
1
)(
)(2
DDAVLr
AVLr
saAVL
VV
VILE
)()( )(1 AVLrces VDUTBVIGBTQ
(10)
如方程所示,雪崩能量由第二电感提供。其抗扰能力与
电感量成正比。焊机电感一般设计值小到几µH,二极
管的这种抗扰能力属于选择器件的一个重要因素。
焊机的次级整流可能发生雪崩现象,尤其当焊机已经工
作结束且电感反向导通时。图24给出了抗扰能力测量电
路,图25给出了雪崩能量测试结果波形。
Q1
DUT(FFA60UP30DN)
Current
Sense
L=50µH
+
-
Figure 24. UIS 测试电路
4µs/div
Isa: 116.8A
Vr(AVL): 432.0V
EAVL=314.8mJ
Figure 25. FFA60UP30DN 抗扰能力
隔直电容
对于半桥拓扑结构,如果两种直流电容或者IGBT
的开通时间不匹配,变压器中会出现直流磁通。直
流磁通累积会导致变压器饱和。这将引起电流急剧
增大,并烧毁IGBT。为了抑制变压器铁芯的直流
磁通,可以在变压器初级串联一个较小的隔直电
容。隔直电容的计算公式为:
swP
D
blocking
FV
IDC
max
(11)
式中, PV 为初级电压中允许的电压跌落,该电压由隔
直电容引起。
下图为变压器初级电流波形。直流偏置将引起变压器
饱,并导致电流突然增大。
Vce_H: 50V/div
Vce_L : 50V/div
ID : 20A/div
100µs/div
* saturation current
Figure 26. IGBT 的饱和电流
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 9
Figure 27. IGBT 饱和电流的放大效果
电源结构与设计
电源中使用了集成MOSFET芯片FSMG0465R。外围电
路简单,开关频率为66kHz,这样大大减小了PCB和变
压器尺寸。另外,待机模式(230VAC输入,0.5W负载
下的功率<1W)下的功耗较低,使得待机耗电量较小,
从而获得了最大的电源效率。也可以采用变压器类型和
开关电源(SMPS)类型做为替代电源。与线性变压器
类型的电源相比,即使在输入电源出现间断、跌落或者
噪声时,SMPS类型电源仍然具有稳定的输出功率,并
且可设计出最小尺寸和重量。此外,变压器类型需要固
定的输入电压,但是SMPS输入电压可在80VAC~264VAC
范围内变化,这使得它可用在各种焊机中,而无需额外
操作。不管怎样,开关噪声将会影响主逆变器,因此需
要考虑防止干扰措施。关于飞兆半导体开关(FPS™)的
更多信息,请参考应用笔记AN-4150,浏览地址:
http://www.fairchildsemi.com/an/AN/AN-4150.pdf.
控制器设计
评估板控制电路使用了PIC16F716。该控制器包括4个8-
位AD转换器端口和1个9-位40kHz分辨率的PWM定时器
端口。为了从一路PWM信号中获得两路PWM脉冲,内
部使用了一个D触发器和一个与门,将40kHzPWM脉冲
分频为20kHz的PWM脉冲(参见图28)。
Low Side Gate PWM (20KHz)
Controller PWM(40KHz)
High Side Gate PWM (20KHz)
Figure 28. PWM 40kHz分频为20kHz
门极驱动器设计
门极驱动器可以使用变压器、光电耦合器或者HVIC。
不同类型的门极驱动所需电源电压列表如下
HVIC驱动器:+15V, 0V(高电平与低电平),
+ 24V, 0V(输出检测),+5V, 0V(控制器)
光电耦合驱动器:+15V, 0V, -5V(高端门极)
+15V, 0V, -5V(低端门极),+24V, 0V(输出检测),
+5V, 0V(控制器)
脉冲变压器:+24V, 0V(输出检测)+5V, 0V(控制器)
光电耦合和变压器可以在控制电路和IGBT提供电气隔
离。然而,由于门极脉冲死区时间电路出现的偏差电
压,变压器可能会导致半桥电路出现交叉导通。通过使
用集成高压MOSFET,HVIC可以在控制电路和高压侧
IGBT之间建立绝缘。这在负电源电压时是行不通的。
在快速换流中,HVIC需要负电源电压,可以防止dv/dt
变化引起的直通。直通的出现与两个IGBT中的任意一
个快速电压变化有关。由于米勒效应,当IGBT关断
时,流经集电极-发射极间电容的电流会引起IGBT门极
电压上升,并引发桥臂出现交叉导通。
C11
10uF/10V
C19104
C20104
D1
1N4937
D2
1N4937
D3
1N4937
-15V
C21104
D4
1N4937
C822P
+15V
+15V
C22104
-15V
J2
Output 12
RD2
ERR
Y1
WLD
C3104
J1
Current Limit
123
C23104
R8
10k R91k
VR35k
VR15k
C6
105
G3
PWR
R6
1K
R13 330
R12 330
Temp
+5V
+5V
J3
CT 12
C4104
R11 330
D5
1N4937
U2A
7474
CLK3
CLR
1
D2
PR
E4
Q5
Q6
U1 PIC16C711
GN
D5
VD
D14
OSC2/CLKOUT15
MCLR/VPP4
OSC1/CLKIN16
RA0/AN017
RA1/AN118
RA2/AN21
RA3/AN3/VREF2
RA4/TOCKI3
RB0/INT6
RB17
RB28
RB39
RB410
RB511
RB612
RB713
J1
TH 12
R110 ohm/3W
X1
20Mhz
C1
22uF/10V
U5
PS25012
35
8
4
6
U6
PS25012
35
8
4
6
VR25k
R20330
ZD!
1N4099
12
R2
27k
U3A
7409
1
23
R3
1k
U4B
7409
4
56
C2104
R19330
R101K
C7104
+5V
C922P
+5V
+5V
+5V
R16 330
R15 330
R14 330
+5V+5V +5V
C12104
+5VBD1
1
2
Gate2_1
C15104
C16104
gate2_2
+5V
RD1SD
G2
Cont-
G1
Cont+
+5V
gate1_2
Gate1_1
R18 1K
R17 1K
C13470P
C14470P
R71K
LVD
R4
36k
C5104
+5V
+5V
R5
560
Q2
2n3904d/ON
Q1
2n3904d/ON
Temp
C10104
PC1PC817
12
43
Figure 29. 控制电路
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 10
IGBT
CCG
CGE
RG
C
E
dtdVGI CGCG /
ICG
dv/dt
dV/dt
Vce
ICG
VgeCGgge IRV
CGCG CdtdvI /
Figure 30. dV/dt 对VGE的影响
Low side gate
High side gate
Current
Figure 31. dV/dt 对门极波形的影响
基于以上基本考虑,本焊机评估板采用了光电耦合器。
图32和图33给出了不同类型驱动的门极波形。显然,本
焊机采用光电耦合器属于最佳选择。
Low Side Gate wave
High Side Gate wave
Figure 32. HVIC 门极波形
Low Side Gate wave
High Side Gate wave
Figure 33. 变压器门极波形
Figure 34. 光电耦合器门极波形
直流电抗器设计
直流电抗器有助于稳定焊机运行中的弧电流。随着直流
电抗器的增大,电弧变小。相反地,如果电弧灵敏度降
低,LDC又太大,就很难产生电弧。因此,选择合适的
电抗器很必要。如果将VOPEN作为空载输出电压,VWEL
和 IWEL 作为额定输出电压和额定输出电流,可得LDC最
大值为:
:
)1( RV
IIn
tRL
open
WEL
R
DC
(12)
式中,R为焊机负载的等效电阻,Tr 为输出电流由零升
到额定电流的上升时间。一旦得到LDC最大值,则可以
通过实验最终确定最佳的LDC取值。
Figure 35. 焊机工作过程中软启动
IWEL: 50A/div
ID : 50A/divVge_L : 5V/div
Vce_L : 50V/div
100us/div
Figure 36. 焊机工作
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 11
结论
根据逆变器拓扑和开关频率,一旦逆变器的功率器件得
到正确选型,DC-ARC焊机可以获得更好的性能。本文
给出了半桥焊机应用的功率器件选型指南。
当选用IGBT时,设计者应该注意其Vce(sat)、Eoff关断损
耗、门极驱动电阻以及Icm特性等关键因素。
选择次级整流二极管时,需要关注Vf 和反向恢复损耗之
中哪一个为主导因素,这取决于系统的开关频率。本评
估板在变压器的每一个抽头上并联了三个超快速二极管
(FFA60UP30DN),用来降低Vf,同时带来导通损耗降
低。
参考文件
[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.
相关资源
FGH40N60SMD — 600V, 40A Field Stop IGBT
FFA60UP30DN — 300V Ultrafast Recovery Power Rectifier
FSGM0465R — SMPS Power Switch, 4A, 650V (Green)
附件-电路图
C5110uF 630V
2
T1
TRANSFORMER CT
1 5
6
4 8
D3 FGA60UP30DN
D7 FGA60UP30DN
D16 FGA60UP30DN
D17 FGA60UP30DN
D18 FGA60UP30DN
D19 FGA60UP30DN
R6
10
- Output
C23
102
R39
10
C24
102
+ Output
ZD81N4744
ZD91N4733
R54.7k
Gate1
Gate2
C5210nF 630V
ZD71N4733
R44.7k
ZD31N4744
ZD41N4733
Z4
FGA40N60SMD
R9 10/3W
C5310nF 630V
Z2
FGA40N60SMD
R3 10/3W
GND1
ZD61N4744
C541uF M275V
C55472M
C62472M RV1
20D431K
RV220D431K
RV320D431K
P10
1
P11
1
P3
1
L6
L5
LF1RFILTER
L4 52uHC2
400V 560uF
Z3FGA40N60SMD
Z1FGH40N60SMD
R8 10/3W
R74.7k
R1 10/3WZD11N4744
ZD21N4733
R24.7k
- +
BD1
GBP5006
2
1
3
4C1
400V 560uF
- BUS
C61
630V
+ BUS
GND2FAN
1
Gate1
Gate2
C5010uF 630V
CT1
JF3250G
1 3
Figure 37. 主电路
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 12/2/11 12
L2 10uH
XY
4.7nF/1KV
R204
1K
F201 250V 2A
U201 FGM0465R
FB4
Drain1
GN
D2
Vstr6
Vcc3
R2011M/1W
C214
47nF
R217
1.2k
C216
1000uF 10V
D202
1N4007
D203
MBRF10H100
- +
BD201
2KBP06M3N25
2
1
3
4
R219
8K
R208
1k
C213
102
C224470uF 35V
R2051K
C207
47uF 50V
PC1
12
R215
10
U202TL431
23
1
D201
UF4004
LF201
30mH
D204
MBRF10H100
L1 10uH
R218
18K
C202275Vac 100nF
C215
470uF 10V
C2083.3nF 630V
R202
270K
PC2 817
12
43
C204
47nFD38
1N4744 1
2
D206
MBRF10H100
T101EER3940S
13
7
8
9
10
11
12
14
15
16
3
1
TNR10D471k
C209 102
R216
620
C210
102
L5
4.9uH
C203400V 100uF
R212
10
ZD2011N4745A
1
2
C223
470uF 35V
+15v
gnd
5v
AC220V H
AC220V N
-15V
GND2
C201275Vac 100nF
R20743K/1W
R20675K
C20533nF 100V
C206
100nF
R210
1W 5
R220
8K
R203150K
Q201
2N2222
R211 10
NTC
NTC1
5D-9
R209
100 ohm/0.5W
GND1
L4 10uH
D205
MBRF10H100C220
470uF 35V
D207
MBRF10H100
L3 10uH
C211102
C212102R214 10
C219470uF 35V
15+v
-15V
R21310
C217
470uF 35VC218
470uF 35V
C211470uF 35V
C222470uF 35V
Figure 38. 辅助电源
Figure 39. 控制器
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