Variable Frequency PWM Circuit IRFP064N

R1,R6,R11 = 10K
R2,R9 = 1K8
R3 = 100 ohm
R4,R8 = 1K
R5 = 22K
R7 = 1M
*R10 = 0.003 ohm
R12 = 3K9
R13 = 100K
R14 = 10 ohm/1 Watt
P1 = 20K (Frequency adjust)
P2 = 10K (Duty Cycle)
P3 = 1K (Current Limiting)
C1 = 1000uF, 64V
C2 = 10nF, polyester
C3 = 100uF, 64V
C4 = 22nF
C5 = 47uF, 35V
D1,D2 = 1N4004
U1 = LM7810, volt regulator
U2 = LM324, Op-amp
Q1 = IRFP064N , IRFZ44, etc. MOSFet

12V Low side and High side PWM Motor/Light Controller IRFZ48N

 

 

Here these two schematics are variations on addition PWM circuit that I designed. The diagrams are for 12V operation alone and there are aerial ancillary (common ground) and low ancillary (common +12V) versions. The low ancillary adaptation of the ambit uses an N Channel FET, the aerial ancillary adaptation of the circuit uses a P Channel FET. N Channel accessories tend to handle added accepted than P Channel devices, they are additionally beneath expensive. The aerial ancillary adaptation of the ambit is advantageous back one ancillary of the bulk has to be grounded.

This Circuit can about-face a adequately aerial bulk of current, an IRFZ34N MOSFET can handle over 35 Amps if affiliated to a able calefaction sink. Higher ability FETs, such as the IRFZ48N or IRF1010Z can be commissioned if alike beyond currents are required. It is additionally accessible to affix assorted FETs in alongside for alike added accepted capacity. Always use thermally conductive grease amid the FET and the calefaction sink, and bethink that the calefaction bore is electrically live.

Inductive endless (motors) may crave appropriate affliction back they can accomplish ample voltage spikes that can accident the MOSFET. Replacing the 1N4002 with a fast accretion diode may advice blot the about-face voltage bang back active an anterior bulk such as a motor. If you use these circuits for abstracts with electric vehicles, be abiding to install a ambit breaker in alternation with the battery, the ambit breaker should be accessible to ability by the driver. This is abnormally important due to the actuality that back MOSFETs fail, they generally abbreviate out, abrogation the motor on at abounding speed.

Note that the pwm ascendancy has an adverse aftereffect on these two circuits, the low ancillary adaptation is on with a aerial pin 7 achievement voltage and the aerial ancillary adaptation is on with a low output.

The inductor on the aboideau ancillary of the ability MOSFET transistor can be a ferrite bean or a few turns of wire captivated about a 10 ohm, 1/4W resistor. The purpose of this allotment is to anticipate RF oscillations from occurring in the MOSFET circuitry.

When PWM is turned on - IRFP450

During the ON time of the cycle, the MOSFET turns on and starts conducting. Since inductor poses no resistance to DC current, large current flows through the MOSFET. This large current then becomes constant at some point during the ON time of the cycle. Due to the property of inductor, the energy is stored in its magnetic field around it.

During the OFF time of the cycle, MOSFET turns off and no conduction can take place. Due to the property of inductor it blocks any change in current. Because of this, the energy stored in its magnetic field is released. This creates high current. But since the MOSFET is turned off, the large current flows through the diode and charges the capacitor.

When the whole process is done fast enough, we are able to achieve a large voltage at the output.

In this experiment, I have used an old inductor from switch mode power supply that I found in the computer’s monitor. So I don’t know the value, but it is definitely greater than 200uH. IRFP450 MOSFET (HEXFET as they call it) can carry 14 amperes of current, and has a very very low drain to source resistance. The reason for using such a large MOSFET is, it does’t heat up. If you use a MOSFET with large drain to source resistance, you are going to get a lot of heat, this increases the possibility of destroying the transistor (I already destroyed like 4 expensive MOSFETs)

MOSFETs are very sensitive to heat and over voltage, so please take care that you do no exceed the specifications. My advice would be to obtain MOSFETs from old power supplies. You can also get a good number of high voltage fast response diodes from those old circuits.

I suggest you to build this circuit and try out different values of inductor and PWM. Here is a small arduino code used for generating PWM with On time of 50 uS and OFF time of 15 uS.

When this PWM configuration is used with my circuit it can yeild upto 394 V. I did not go beyond that, because the capacitors I have used are limited to 400V and so is the diode. So it is better to be safe below the range.