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44 Threads found on Zero Voltage Switching
hi, I need explanation of zero voltage switching in Induction Heating devices. Is there any special circuit used to achieve ZVS? or it is achieved via coil and matching network design? Regards
hello I am in confusion about when to use the signal of current zero crossing and voltage zero crossing. I am sure that when I switch on a relay, it is best to fire it at voltage zero crossing, but regarding switching off the relay, should I switch off it at voltage (...)
Do you mean that coil current should drop to zero before a new cycle begins? Find the proper point where you can monitor voltage (or current). Tap at that point, and it can serve as a feedback signal. This simple boost converter is a good example how to do that. It takes feedback from the node between inductor and switch. It applies it as a contro
What you probably want, is to measure each shunt at two timepoints, one where the result is "zero" (like, switch is off, right before next turnon) and then another where the voltage is significant and most stable (dead quiet in a switcher, ain't gonna happen - but pick the best, perhaps right before switch turnoff). There exist integrated shunt-a
Dear All, i am trying to simulate following circuit. When i switch on the MOSFET momentarily at zero crossing of the Iin, and measure voltage across the capacitor(C1), am i not supposed to get response resembling a square wave? I think momentarily switching the inductor at zero crossing of Iin, should flip the (...)
Well i have an assignment to make inverter using ZVS topology. i have made it before using this design. pic microcontroller will generate oscillations . ir2110 driver will be used for mosfet driver and that's all. i have made it before without zero voltage switching . I have read a lot of webste's but i have not understand this (...)
Hi, I was wondering whether switches in an inverter get rid of ringing completely by utilizing soft switching techniques. For instance suppose I have a full-bridge series-loaded resonant converter using Mosfet switches . Is it possible to eliminate ringing at the turn on and turn off instant by using zero voltage (...)
Hi, I was wondering whether switches in an inverter get rid of ringing completely by utilizing soft switching techniques. For instance suppose I have a full-bridge series-loaded resonant converter using Mosfet switches . Is it possible to eliminate ringing at the turn on and turn off instant by using zero voltage (...)
hi, How zero-voltage and zero-current switching are achieved in resonant converters? what is the working principal?
If you have a DC supply for a motor being controlled by a SCR or thyristor then switching the device off would have no effect until the current through it falls to a low value (Ihold). This would occur naturally if the DC supply was unfiltered since the voltage would fall to zero between every half cycle. If you connected a second device (...)
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 (...)
Hi, i'm designing and realizing on prototype board a full bridge class D amplifier. The switching losses of mosfets are higher than those provided by the calculations. The DC voltage is 250V and Fswitching=50KHz Pout=150Wrms. My question is: is there in literature a ZVS class d amplifier example? Is it possible to realize it? I
Generally one uses a "diode OR" function. Connect a diode from each source to the load. Whichever source is supplying a higher voltage turns on its diode and supplies the circuit. Any sources that are not active generally supply zero voltage. In your case set the AC supply to provide a little higher voltage than the (...)
Hi all, Designed Flyback Topology based SMPS.Now want to convert SMPS in to zero voltage switching Flyback SMPS. How to design ZVS Flyback Converter? Thanks & waiting For Knowledge Enhancement,:thinker: Sachin
Power Supplies for PC's are cost reduced so much that there is no excess storage energy to sustain a missing power cycle or two, so DC drops like a brick.I dont know the dead time on your UPS AC power transfer switch.A synchronous SSR transfer switch may help reduce the glitch by switching at a zero current crossing of the generator, but not cheap
Do you have an idea of the expectable switching delay and delay skew of mechanical contactors? Review data sheets and reconsider the idea of switching electromechanical relays synchronous to zero crossing.
I need to switch between 0v to 20kv. I was fooling around the internet, but I am not sure what to use. I need a short pulse, like for 1 second it should be ON and then goes to zero. Not more then 1 second. Can anyone suggest me something what to use? Of course I dont have budget for $300-400 devices :-(
I am making a solid state relay using mox3040 zero cross detection and BTA12-600 Triac, The purpose of this Project is to switch the power source on failure in minimum possible time, For failure detection, I am using ADC of 18f452, by sampling whether the power is fail or not , In general we know that its best to switch On triac when voltage
switching off a DC current powered by a high voltage source produces an electric arc much stronger than in case of AC. In case of AC, the strength of this high electric field that is built between the switch contacts (to cut off the current) is reduced automatically when the AC voltage (its absolute value) decreases and crosses (...)
Hello, I am hoping that somebody can help me out. I am trying to simulate a power supply in Ltspice and I am having a problem This power supply is a zero voltage switching isolated full bridge converter. It take 18-30Vdc in and outputs 165V at 120W (0.7A) The problem that I am having is that the regulation poor. Also when the (...)
Dear friends , I m working on a project : zero voltage switching ...relay based stabilizer..... Please suggest any design challenges faced.... So far i have to sense the ac mains voltage ...and based on the voltage , i have to switch the tapping of autotransformer through relay.. Now i am planning (...)
The circuit operation mode is still partly unclear. How about load current, voltage induced in the primary winding by the load current? How do you assure that the primary voltage doesn't exceed the maximum triac voltage? Regarding triac triggering, what's the trigger circuit, do you perform zero (...)
AC SSR means that the load can't be disconnected before the capacitor is fully discharged. I guess that's no problem. Secondly the SSR must not have zero crossing switching logic, otherwise it would never trigger with DC voltage applied. Most AC SSR are equipped with zero crossing logic, however. Finally, the SSR (...)
Thank you. Well, if I use that circuit, do I still need a zero crossing detection circuit?
Where do you see dead times "eaten up" in your diagram? It's actually an unknown combination of transistor switching times and load dependent H bridge commutation behaviour. Without a load resistance, the output voltage (tp1) doesn't change before the load side switch is activated. Seeing Vgs dropping to about zero (first step in tp2) (...)
i am doing a project of boost converter using zero voltage switching (ZVS), the overall schematic shown in figure below. am using timer 555 to generate PWM to trigger the mosfet, the frequency about 600hz, Vin = 12v, Vo=47.5v, duty cycle = 58%, so my problem is how to calculate the resonant components (L2,C5) to achieve the soft (...)
Even humble 4066 CMOS switches are good to several MHz. I've use 74HC4351 CMOS switches at 60MHz without any problems. Provided you ensure the signal voltage falls within the switch supply rails it will keep it's zero point. Brian.
What's the input voltage switched to the 97V tap of the transformer? switching a transformer load at zero crossing effectively "guarantees" core saturation during the first AC cycles, unless the transformer is designed for a very low flux. The saturation current (probably > 500 A for a 7.5 kVA transformer) can easily destroy the triac. (...)
are you trying to control motor speed? if so it is not normally done with a zero-crossing switch, because the phase difference between voltage and current is not zero. So you switch off on zero voltage, but current still flowing - you are simply asking for a very big voltage spike across (...)
It's exactly what the name suggests. Something is switched when the voltage across it is zero. You usually find the term used in power switching applications, consider that in AC or rectified AC circuits the voltage is constantly changing. If you switched the power at peak voltage you risk arcing or large (...)
Power switching by FETs is preferable, if you need near to zero voltage drop. But FETs are conducting bidirectionally, so you they can't operate self-controlled.
As the main problem of the original circuit, the MOSFET will never turn off, because there's no means to pull down the gate voltage to zero. Actually, the motivation for the circuit design is completey unclear to me. What I would do: Use a zener diode to generate a voltag level within the MOSFET and photo transistor ratings, e.g. 10 to 15 V with
The zero mains voltage waveform is more or less meaningless, but it doesn't seem wrong anyhow. The 10V AC waveform shows the output transistor in operation. You must consider, that you won't see a squarewave at this high operation frequency rather than soft, resonant switching. Most likely the waveform shows regular behaviour.
Keith is absolutely right. There is another issue though, you want the output to go to zero when the input is zero. If you mean voltage, this will never happen in an inverting configuration. think of the transistor as being a switch between collector and emitter. To make current flow you close the switch, to stop it you open the switch. (...)
hello please can you tell me how the circuit on page four of this..... ...manages to give zero voltage switching (ZVS) of the two mosfets? is it due to the capacitor "CDC" which acts with the inductor "LRES" to make the bridge node (node between fets) slew such as to make th
hello, the offline CFL ballast on page one of ...does zero voltage switching of the fets (zvs). In fact, all Fluorescent ballasts of reasonable quality give zvs operation. so.....please could you tell why an engineer at a big lighting exhibition told me that the fets intri
The power MOSFET gate charge is shuttled once a cycle, ditto the loss-slug as the FET transitions through the dissipative region (zero voltage, zero current schemes are for this). More cycles per second, more joules per second (i.e. loss watts).
The IR2110 is meant to be used in a switching circuit, that is the output has to go to zero periodically. I suspect you are trying to apply power continuously to the load. If that is the case, then this will not work, because the IR2110 needs to charge up the bootstrap cap and that can only happen if the load voltage is allowed to (...)
I'm working on a project that will consist on switching a Vending machine on and off with a IR remote using a Microcontroller. The schematic for the circuit is attached. I need to know what other additional protection will I need when I switch on the relay, like for example switching it on when a zero of the voltage is (...)
"zero Crossing Detectors and Comparators" Regards, IanP
zero switching noise since the TRIAC's/SCR's are fired at zero crossing of the mains voltage. Cheers Ravi
It is too much question to answer and need too time to answer it,but I try: 1. DCM and CCM will effect effieciency,EMI,LOOP control,but it not simple difference. 2. soft-switch mostly is mean ZVS(zero voltage switching) and ZCS (zero current switching) 3. use resonant tech to realize zvs or zcs 4. (...)
ZVS is a technique used in switching power supplies to reduce switching losses. The idea is that switching losses occur whenever there is overlap of voltage and current through the devices. Therefore, switching the device when either the voltage or the current is zero will (...)
It is the rule called Volt-second balance (Vs). It is integral of voltage across inductor during switching period. That means that average energy through inductor is zero (also average voltage across it). This is used in buck , boost and buck/boost dcdc converters. Similar is for capacitor but there is Is balance that means (...)