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424 Threads found on Voltage Smps
Hello, Here is two identical Full Bridge smps simulations in the free LTspice one has leakage inductance in the transformer, the other has perfect coupling (no leakage inductance). Notice how the one with leakage inductance has far less severe reverse recovery of the secondary diode. (attached are waveforms of secondary diode voltage (green) and
The effective gate charge that must be delivered by the gate transformer will considerably increase when the supply voltage is turned on. In addition, transformer inter-winding capacitance can have an effect. The first (no supply) waveform already suggests that the driver circuit is much too weak. It takes several microseconds to charge the gate
Yes you can simulate that to demo the point. Those diodes aren?t necessarily only for parallel smps, they can be used with a single smps. Its just that when an smps goes into no-load, its error amplifier tends to rail low?..the error voltage just plummets all the way down to the rail?..this is a problem when it is (...)
Presumedly the smps won't run with 24 V bus voltage, a typical wide range circuit has an undervoltage lockout threshold of 80 - 100 V. It may be possible to perform some functional tests with lower input voltage, bypassing the UVLO and startup circuit. But only at small fraction of rated output. Standard equipment for (...)
As a general rule switching power supplies have the - terminal referenced to earth ground. If you try to put two of these is series they will fight each other, as the minus terminal from the two supplies are both probably connected to case/earth ground. I share your concern FlapJack. But this particular supply has
You must find out why your hydro electric is upsetting the smpss. Is the voltage wrong or the frequency wrong. I have come across industrial size (250kW) maintained supplies which do not recognise the incoming mains if its more then 1% off frequency. Frank
How should I monitor the output voltage of a boost converter? for example I have a boost converter with output voltage of 60V +/- 5Vand I have a voltage sense that sense the change of these value, should my voltage sense monitor the levels above the its maximum or below its minimum level? anyway the (...)
you don't need "bleeder" ..voltage is too low at output to be dangerous, in any case, the leakage current of the electrolytics will bleed it down, - - - Updated - - - Hello, That?s a lot of secondaries that you?ve got there, and are you sure that the ee25 bobbin is actually deep enough to be able to ta
whatever value keeps the voltage at the mid point within say 1% of the nominal. Also, ensure no overly high ripple current in them.
firs of all do you think it's okay to feed two transformers from a single two switch half bridge ? given that the mosfets or IGBT's are powerful enough for the job? i could increase the startup capacitor on the SG3525, though even with this one the starting up is slow enough for me to see the voltage rise gradually over a sec or two on a simple
I am a beginning electronics hobbyist and I have never designed electronics. However, I'm somewhat familiar with power electronics from my work. I tell this that you can put my writing to proper context. Thanks, when I worked at an amplifier company, everybody was going on about igbts that can replace mofets, in 300w+ smps,
Reminds me of the adapters that come with a Universal Laptop charger coaxial plugs with a multi-wire interface. One of the wires to the smps charger was voltage sense and Gnd sense to regulate voltage at point of entry for loss in the wires.(remote sense) I modified the cable so I could adjust the output of the 19.2V 65W supply with pot, (...)
Hi folks , so I built an smps from a schematic found on the internet. it works that far it's okay but it worked when i had a 70w load light bulb attached to the output , after i tried going with a 500w bulb things just went bananas aka exploded , everything in the chain was dead and cracked open , both IRFP460 the IR2110 and also the SG3525 was dea
How to control the Magnetizing current..?? I have an toroidal transformer with ratio of 1:10 for 40 amp secondary at 15v. The transformer primary Resistance is in miliohms. I am trying to switching the transformer with triacs but the triac of 15 amp rating does not handling the Magnetising current at start up. Can anyone having solution
Ropt should be connected to d1 cathode really. Rc is too big value at 1.6megohms - - - Updated - - - These are often due to tripping some protection mechanism in the controller. Eg UVLO, output overload, overvoltage on bias coil etc
I have designed adjustable output voltage and curent smps having 500W output. I would like to share circuit schematic since there are many experienced people in smps and power electronics in this forum. Do you have any suggestion about this circuit ? or Do you see any critical fault ? This project may help to people who want to build a (...)
I am planning to design smps that has variable output voltage and current. Its voltage will change 0-50V and current will change 0-10A. 120251 Vout comes from output voltage up to 50V. Iout comes from output current up to 10A. Iout will be Rshunt x 10A. Rshunt is 0.05R, so Iout will be 0.5V as voltage. (...)
I got my simulation to work on multisim but would need to build the actual smps. The microcontroller I'm using is only capable of outputting 5V. I would need it to be 18V like it works at in my simulation. Is there a way to get the voltage up so it can drive the gate of my mosfet? I've thought about using a gate driver ic but don't know what to buy
Hello, We have had a 3kw offline (85-265VAC) battery charger made for us by a consultancy. They did not give us the schematic. The chargers are failing and we are wondering why. First of all we are trying to assess what topology it is. The schematic that we have determined so far, by using the DMM on the PCB is as in the pdf. However, when we
The zener clips the + base drive pulse to bypass the base current and drain the 0.004 cap to reduce the output voltage. Raising the Zener voltage increases the duration of pulse and saturate the core more.
Hi FvM, Thank you for your answer. but i have a remark, if i supply the opamp by the output voltage i inject many noise to my OPAMP. 2) the output voltage vary = supply OPAMP very !! (and the offset of OPAMP change !!) 3) is it possible to use an other solution for driving this inverter without negative supply ? Thank's Paul
The np/ns of the present design is that of a typical wide range off-mains smps. It's expected to work over a e.g. 90 - 240 or whatsoever input voltage range. I must confess that I don't understand what's the problem presently discussed in this thread. You have initially asked about snubber power dissipation, and it seems to me that the calculati
Hi there, I need some advice and guidance. I have this design specifications for the almighty smps :( 1)Input voltage : 24V-270V AC/DC (Universal Range) 2)Power Rating : 20W 3)Output voltage : 20VDC 4)Output Current : 1 - 2A 5) Isolated Add 1) I have troubles with this specification. Mainly ICs used in AC/DC converter (...)
Hello, The following two LTspice simulations are almost exactly the same (both full bridge smps?s)?They have the same NP/NS value, but slightly different primary and secondary inductance values. Everything else is the same about these smps's. So why does the one with lower primary inductance have a higher output voltage? (316V (...)
THe ground shield is normally connected to power ground pin, but in situations where ground faults or high return DC currents cause offset voltage or injected noise into the common mode ground, designers may choose different methods of grounding for special situations. EMC is a two way situation for smps ingress with switching frequency nois
Thanks, yes i saw that..on page 5 of the datasheet it does indeed say "2mA"....However, the minimum pull-up resistance to the VREF is 3kohms...and the reference voltage is 3.9V in such a case, the opto would have to drop (3.9-0.8) = 3.1V across the 3K internal pullup, so that?s a opto transistor current of 3.1/3000 = 1.3mA ,
I see your point, but isnt 418v a bit near the 450V "common" voltage of the electrolytics at the output of the you know, pfc's are slow and if suddenly no-loaded, the vout could go above 450V. Our transient protection is via a MOV which is after the emi filter, and just before the diode bridge. We put it there because we want it to las
Hello all, I would like to vary the output voltage for my buck converter by a vary between 0 to 3.3V V_HV vary between 0 to 100V Can you help me how calculate the relation between V_DAC and V_HV :bang: How i calculate R1, R2, R3 :?: 117186 Thank you
Hi everyone. i have an oven with an electronic board that not working this oven have three electronic boards. 1) power supply 2) power (with relais) 3) control (with buttons and display) what does not work is the power supply. in input there is 220 vac but in output there is not 9.5 vdc. i tryed to replace an
Neutral ( near ground ) has nothing to do with an isolated output, nor does a resistive load. But best test method is active load test with MOSFET bank and control voltage with current sense and step load tests, cross load regulation etc., water cooled. or external dummy heater load resistors ( ceramic heaters are cheap.) or use Nicrhome wire in
A better Bang for the Buck (intended pun) is to design a low voltage drop linear regulator after the buck smps which maintains the constant low voltage drop, while the linear regulator minimizes the ripple and has the benefit of current limit control down zero with wide BW ripple rejection and low step-load regulation error. In the old days (...)
Do you plan to connect or disconnect heavy loads from the secondaries? This will affect output voltage at the other secondaries, even if it is for a moment. It is an issue you need to factor into your calculations for voltage levels and how to regulate them.
A PV is essentially a lossy current source that has a zener like open circuit voltage, Voc that declines slightly with lower solar input. The maximum power point is approximately 80+/-5% of Voc when the VI product has a shallow peak in power about this centre. You can hunt for this peak using MPPT regulated current sinking smps or approximate it
Hello, Pages 14 and 15 of the NCP1217 PWM controller datasheet show that PWM controllers with an internal high voltage startup regulator have a definite chance of destroying themselves with destructive latch-up at power down. The NCP1217 datasheet shows how to add external components in order to prevent this from happening. (Eg with a flybac
Yes its possible. I have used an MCU as PWM regulator with voltage and current feedback loops and other interface as well. If you do it right you might be able to increase the overall efficiency. ATMEGA is relatively more expensive than other MCUs I used. Microchip's PIC16F18xx series can be considered and if are able you can use NXP's LPC11xx whic
I think it will be better if you share more on what information is available with you - so that others can help you faster. One option is - if you are able to scope out the voltage @ diode in secondary or the current through the diode - all before the capacitor in secondary, you can measure the switching frequency.
You need to understand Ohm's Law and basic electricity to see how much current is used. The rated current of a power supply is the maximum current it is allowed to provide. It does not provide that much current all the time. Ohm's Law says that the current is the voltage divided by the resistance. You have a load that uses 600mA when the
Hello, Please can you confirm that when the primary FET switches off, the voltage across the leakage inductor, which resets the leakage inductor, is the (RCD clamp voltage) minus the (voltage referred from secondary to primary)? ....and if these two voltages were equal then there would be no voltage (...)
In case of doubt, a solid ground plane won't be bad. The LED driver circuit can't work. The IR-LEDs have only 1.2V forward voltage each, so a simple series resistor from 5V would be the appropriate way to supply it, or a buck converter if minimal power consumption is a must.
Hii . I want to design smps based battery charger, that can charge the battery at constant current 1amp (adjustable) with 14.1volts(adjustable) and after full charge it gives the constant voltage 13.6volts to the battery... My battery specifications is 12v 7.2ah sla battery So how to proceed?
Hello, We wish to scope the voltage across the output diode in our offline , isolated flyback smps. (to see how high the ringing voltage goes) Should we use a differential probe, or will it be accurate enough to simply connect the actual scope probe directly?
I want to know the maximum voltage and current output of a desktop computer power supply.
So it not going to be in very harsh conditions... Will have to re-read the spec to get pollution level If the board develops cracks you are going to be the unluckiest designer in the world.... because it would be the layer to layer clearances that would be affected and if you have high voltages then the design should be done so that cracks etc. do
NOT quite. He states how it is more useful to skip the frequency domain simulation and start with time domain simulation to optimize stability of overshoot. He points out how to stay in "current-mode" so that it becomes inherently stable. Use variables are input voltage and output step currents. Design choices depend on priorities, cost, per
What are you using it for. If just basic scoping low frequency signals then almost anything will do. If you want to depict ringing and peak drain voltage spikes in smps's then you will need high bandwidth. Beware some of the Far eastern ones where the save_waveform feature doesn't work on windows 8. Do you need sample and hold....if so, don't buy a
You can use an isolated gate driver like TLP2200. Problem in any case is that you need a low voltage supply for the gate driver. Usual solution in regular smps: Startup circuit is deriving the supply voltage from input DC voltage by a series resistor + Z-diode, in operation an auxilary transformer winding is supplying (...)
Full Bridge smps primary DC blocking capacitor...(capacitor in series with primary) Does any reader know of a book that explains ...... 1. Whather or not this capacitor is needed in voltage mode control? 2. Whether or not this capacitor is needed in Current mode control? 3. Whether or not this capacitor is needed in Current mode control
it means that you have an smps where as soon as the inductor current falls to zero, the driving voltage is again forced across the inductor and the inductor current begins to build up again. So the inductor current falls to zero , but does not languish other words, the inductor current is triangular and not trapezoidal, and there are n
I could not find the proper spec sheet for transformer which determine the power or voltage current rating of transformer. I also could not find the turns ratio. If u know the cross sectional area of input and output coils with their length, the resistance of coils can be found. Using these values u can determine the VA rating and with power factor
Hi all I have some stupid question about ac-dc conversion. As you already know, diode-bridge is connected to AC line and rectified voltage is go through flyback stage in case of flyback ac-dc smps. - AC Plug -> Diode bridge -> Flyback stage Then let me write a stupid question. How about below construction? - AC Plug -> transformer