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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
Hi, There are ready to buy isolating solid state relays. Use one with zero cross acting. Klaus
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 zero crossing or current (...)
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 voltage across C1 and i (...)
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 term a
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 switching (ZVS) ? Does (...)
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 switching (ZVS) ? Does (...)
dear friends i m trying to implement 3pole 3 zero compensator for sinewave UPS i have transformer with leakage inductance of 31uH and output capacitor (AC) is 0.47uF i m not able to place the proper zeros due to very less switching frequency(17kHz) kindly help
hi, How zero-voltage and zero-current switching are achieved in resonant converters? what is the working principal?
This would appear to be fairly similar to your original proposition of 50/50% duty cycle at zero speed, switching diagonal pairs together. No. The original circuit was applying bipolar (two-level) pwm, 50 % anti-phase switching at zero speed. Other than unipolar (three-level) pwm, it involves a large ripple current with (...)
If this is 3GHz continuous / balanced (-ish) switching then it could be as simple as a blocking cap and a bias resistor network on the other side. zero delay and trivial loss are upsides, the need for some preamble period for the bias network to stabilize could be an application issue. Does it really need anything more elaborate, and if so, why?
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 across t
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 Lambda
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 battery, but both within the
how to make a ssr using triac to switch 5aurrent at 230v rating. please post any circuit diagram what is the term zero crossing detector in triac drivers such as moc3041 what is the use of it can i use moc3021 for switching application that is triggering triac please suggest some circuits regards kalyan
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
The observed circuit behaviour looks expectable. The comparator threshold is zero without a hysteresis, so it will be switching with no input signal. I have a different problem with the circuit, I don't understand it's purpose. Why would we send the output of a comparator, amplified by another transistor stage to an ADC?
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
Page 7 (LHS) of the following (below) article is totally wrong, do you agree? It says that regarding active clamp forward converters, ?With sufficiently fast gate drive, the turn off of Q1 can be virtually lossless.? (Q1 being the main power mosfet). This is impossible, current cannot suddenly go to zero in Q1 and cannot immediately diver
I design a board with 3 triac output. The power supply is 220VAC and i want to give 150VAC to a load. The load i a switching AC/DC load with power max cons. 40VA. I detect zero cross and i trigger the MOC for 1ms only. The problem is that after some times a triac is "burned". I am using the below curcuit. Can you help me?
I am using a dc supply rectified output from the transformer to make my dc link for inverter circuit.I am using ir2113 and igbts for h bridge switching. when i powered on my ir2113 supplies,pwm for igbt is zero(no turn on state for igbt ) the dc link capacitor starts charging.i tried 2 pin connection to eliminate possible grounding current.but sti
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.
Hello, The Active clamp forward can certainly be arranged to have zero switch_on switching loss (by suitable sizing of the leakage inductance). Since at switch off, much of the FET drain current is diverted into the clamp capacitor, (ie rather than it going through the drain_source of the FET) can we also say that the switch_off (...)
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 :-(
If I have a switching quadrature demodulator with a differential input and I purposely set the H input at a slightly higher DC offset and the L input at a slightly lower DC offset then anytime my L.O.'s I and Q switching inputs are not each exactly 50% duty cycle it will cause my I and Q zero IF outputs to have a DC offset. If I integrate (...)
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 zero volt.
Hello, The switching loss of a DCM flyback is virtually zero at turn on (because theres no current flowing)...........however, it has high switching loss at turn off.......supposing I add an RCD snubber to the fet...............can I confirm that this doesn't make for overall efficiency increase, but does make dissipation in the fet less?
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 input v
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 to use the zvc optocoupler like moc3061 fo
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 voltage switching? Otherwise the other triac w
LED current is too low, refer to datasheet specifications. 10 nF doesn't involve much snubber effect. It may be problematic to use a zero crossing switch with mostly inductive loads like solenoids.
MOC3041 has inbuilt zero crossing detor ckt. it'll trigger the TRIAC when the supply crossing zero (zero volt switching). If u r trying for phase angle contro method u need to use MOC3021. Ref: use the ckt on pg no. 4 includes a capacitor which will act as snubber will give be
Hello, what is the formula for MOSFET switching losses & Rectifier diode losses? and please explain me how to calculate them? Hi Madhu.b switching loss of a mosfet will given by : 1/T integral over Rdson*Id^2 dt from zero up to ton . and fo a diode : 1/T integral over Vdon*id^2 dt Best Wishes Goldsmith
Hello, This is a really big problem in using triac for switching AC devices using microcontroller and optocoupler.I made a circuit which uses optocoupler MOC3041 and triac BTA16-600BWG.Due to the minor delay in switching of Triac there is a jitter at the zero crossing of the signal.This has resulted in burning of coil in my lower quality (...)
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 should have (...)
zero crossing optocoupler MOC3041 is suitable in this is not phase angle control but on/off with 3-5 degree hysteresis.
Thank you. Well, if I use that circuit, do I still need a zero crossing detection circuit?
Hi - I have a synchronous voltage mode boost converter design using the TI TPS43000 that is giving me headaches. Its stability seems to be fairly load dependent, which doesn't make a lot of sense to me. With my current compensation network, it oscillates at low loads, but not high loads. Can anybody suggest why the load current is affecting my stab
Dear VJKris Hi In fact as we know Vave of each square function will given by 1/T integral over Vs dt from zero up to ton . if we solve it , we will have Vave= VS*D.C ( D.C is duty cycle ) . so that inductor and capacitor will provide a 2nd order integrator circuit to take average from square wave , thus if you change the D.C the out put volta
The body diode has no role, it's just there by construction. You don't want to light it up, although there are some FETs that have made it fast-recovery and allow / feature it. Load dependent losses are conduction losses. Light-load losses are switching and housekeeping fixed losses, against a zero-ish numerator (Pout) in the efficiency calcula
I have been wondering why drain current decreases a little and then dramatically drops to zero after reaching the peak in class E power amplifier when the switching transistor is on. I understand that it is because the transistor is turned off so that the drain current starts dropping dramatically to zero. But what really causes the current (...)
I have been wondering why drain current decreases a little and then dramatically drops to zero after reaching the peak in class E power amplifier when the switching transistor is on. I understand that it is because the transistor is turned off so that the drain current starts dropping dramatically to zero. But what really causes the current (...)
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) suggests corr
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 switching. (...)
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. The trans