MOSFET AS HV SWITCH.
in most of applications we need to use use mosfet as switch. because mosfet is powerful device which can handle large amount of current. here i will discuss how we can design mosfet switch above 20 voltages.
in present time mosfet use almost in all power and control systems. where we use voltages above the 20. as you know mosfet work under 20 voltages without any problem . the reason is Vgs.(voltage gate source).in most of applications we use 24 , 48 , 60 , 72 and so on . these voltages are above the common mosfet Vgs which can damage the mosfet. in electric bikes electric cars we use 48 , 60 and 72 dc voltages respectively . here we discuss how to manage proper Vgs.
Pic from google.
in our discussion we will chose IRFP260 mosfet . which is 200v mosfet . it can carry huge current upto 50A. the Vgs of IRFP260 is 20V. if we use this mosfet under 20 volts we don,t need any extra circuit to minimize Vgs.
1) First method is using zener diode we can acquire Vgs level.
In figure there is a 12v zener diode as voltage regulator . here zener diode give fixed 12v . which we use as Vgs . at gate terminal we used a BJP transistor as input switch . apply input signal at Rb . calculate the value of Rz. This circuit can work upto 100v. this switch can be use in solar applications .
P CHANNEL MOSFET AS SWITCH .
In some applications we need p channel mosfet as switch. We can use same method for vgs . the IFRP5210 is p channel mosfet which is 100v and and -40A mosfet
Pic from google .
we are using p channel mosfet as switch . zener diode is using as voltage regulator . in this circuit we use a capacitor which minimize the amount of inrush current
This switch is very useful in solar application special MPPT . Buck converters and so on .
Mosfet as switch using voltage regulator.
There is another way we can use voltage regulator . there are several kind of Voltage regulator . which can regulate the voltage from 10VDC to 450VDC . this method is very easy to acquire the Vgs level .
constant Vgs level . LM317HV can regulate volatge upto 60. this switch can be use in motor applications.
There are many types of voltage regulator,s for high voltage for example TL783. it,s maximum input range voltages are 125v . another is LR8 . there is LM317 voltage regulator. It,s provide er HV regulate . which input voltage range is 13.3v to 450 v.
APPLICATIONS.
1) MOTOR CONTROLLERES.
2) INDUSTRY HEATERS.
3) SOFT START.
4) SOLAR APPLICATIONS.
5) MPPT.
6) SMPS.
7) INVERTERS .
By usman umer
