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參數(shù)資料
| 型號(hào)： | DSC-10510-514 |
| 英文描述： | Converter |
| 中文描述： | 轉(zhuǎn)換器 |
| 文件頁(yè)數(shù)： | 5/12頁(yè) |
| 文件大小： | 110K |
| 代理商： | DSC-10510-514 |
5
Data Device Corporation
www.ddc-web.com
DSC-10510
H-02/02-250
THERMAL CONSIDERATIONS
Power dissipation in D/S and D/R circuits is dependent on the
load, whether active (TR) or passive (CT or CDX), and the power
supply, whether DC or pulsating.With inductive loads virtually all
the power consumed will have to be dissipated in the output
amplifiers.This can require considerable care in heat sinking.
Example:
For illustrative purposes the following thermal calculations are
made using the DSC-10510
’
s specifications. The DSC-10510
has a 7 VA drive capability for CT, CDX, or TR loads.
Simplest case first:
Passive Inductive Load and ±15 Volt DC
power stage supplies (as shown in Figure 2)
. The power dis-
sipated in the power stage can be calculated by taking the inte-
gral of the instantaneous current multiplied by the voltage differ-
ence from the DC supply that supplies the current and instanta-
neous output voltage over one cycle of the reference. For an
inductive load this is a rather tedious calculation.Instead take the
difference between the power input from the DC supplies minus
the power delivered to the load. An actual synchro load is highly
inductive with a Q of 4-6; therefore assume that it is purely reac-
tive. The power out, then, is 0 Watts. As a worst case scenario,
also assume the load is the full 7 VA, the converter
’
s rated load.
The VA delivered to the load is independent of the angle but the
voltage across the synchro varies with the angle from a high of
11.8 Volts line-to-line (L-L) to a low of 10.2 V L-L.The maximum
current therefore is 7VA/10.2 V = 0.68 A rms. The output is L-L
push-pull, that is, all the current flows from the positive supply
out to the load and back to the negative supply.The power input
is the DC voltage times the average current or 30 V x (0.68 A x
0.635/0.707) [avg/rms] = 18.32 Watts.
The power dissipated by the output driver stage is over 18 Watts
shared by the six power transistors. Since one synchro line sup-
plies all the current while the other two share it equally, one will
dissipate 2/3 of the power and the other two will each dissipate
1/3. There are 2 transistors per power stage so each of the two
transistors dissipates 1/3 of the power and the other transistors
dissipate 1/6 of the power. This results in a maximum power in
any one transistor of 1/3 x 18.32 W = 6.04 Watts. The heat rise
from the junction to the outside of the package, assuming a ther-
mal impedance of 4
°
C per watt = 24.16
°
C. At an operating case
temperature of 125
°
C the maximum junction temperature will be
149.16
°
C.
The other extreme condition to consider is when the output volt-
age is 11.8 V.The current then will be 0.42 Amps and the power
will be 30 x (0.42A x 0.635/0.707) = 11.32 Watts. A similar cal-
culation will show the maximum power per transistor to be 2.3
Watts. This is much less than when the output voltage is 10.2 V.
For
Pulsating Supplies
the analysis is much more difficult.
Calculations for a purely reactive load with DC supplies equal to
the output voltage peak vs. pulsating supplies with a supply volt-
age equal to the output voltage yield
an exact halving of the
power dissipated
. At light loads the pulsating supplies approxi-
mate DC supplies and at heavy loads, which is the worst case,
they approximate a pulsating supply as shown in Figure 4.
Advantages of the pulsating supply technique are:
Reduced load on the regulated ±15 VDC supplies
Halving of the total power
Simplified power dissipation management
+15VDC
-15VDC
LIGHT LOAD
HEAVY LOAD
FIGURE 4. LOADED WAVEFORMS
REF IN
D/S
R2=1 1/3
R1=2/3
REF
ZSO=8.6
NOTES:
R1 + R2 ZSS
3-WIRE SYNCHRO
2-WIRE REF
ACTIVE LOAD
FIGURE 5. EQUIVALENT 2-WIRE CIRCUIT
FIGURE 6.TORQUE SYSTEM
R1
R2
R1
R2
REF
REF
TORQUE TRANSMITTER
TORQUE RECEIVER
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DSC-10510-514L | Converter |
| DSC-10510-514Q | Converter |
| DSC-10510-514S | Converter |
| DSC-10510-523 | Converter |
| DSC-10510-523L | Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DSC-10510-514L | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Converter |
| DSC-10510-514Q | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Converter |
| DSC-10510-514S | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Converter |
| DSC-10510-523 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Converter |
| DSC-10510-523L | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Converter |
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