Is it harmful, If I supply 230V, 50Hz "square wave" power-input to a electronic device with SMPS (Such as TV,PC.. originally designed for 230V, 50Hz ) ? Or due to the SMPS wont it be a big problem ?
It's more about how the transformer will deal with higher frequencies. Power transformers are low frequency. Higher frequencies could cause humming, best case, or transformer failure in the worst case.In general very few SMPS based device are all that fussy about what sort of input power they get
Where does the OP mention anything about a transformer? You do know what a SMPS is right?It's more about how the transformer will deal with higher frequencies. Power transformers are low frequency. Higher frequencies could cause humming, best case, or transformer failure in the worst case.
Designed my first switching regulator about 40 years ago. That was long before you could buy a switching regulator IC that gave you examples of buck/boost applications, so you needed to understand the theory...Where does the OP mention anything about a transformer? You do know what a SMPS is right?
Trained engineer trying to help people for free. Retired and nothing better to do... How about you?Are you bored, inebriated, high or just looking to troll someone for something to do?
Papabravo said:
Is it harmful, If I supply 230V, 50Hz "square wave" power-input to a electronic device with SMPS (Such as TV,PC.. originally designed for 230V, 50Hz ) ? Or due to the SMPS wont it be a big problem ?
That would be my thinking. Devices like my home computer and my TV as well as cordless telephones have no problems at all with power from UPS units which output a "Modified Sine Wave" which pretty much looks like a square wave. Some devices with linear power supplies using some transformers may not care for the square wave or modified sine wave input. So in a simple nutshell it all comes down to the device. Some will and some won't. Never gave it much thought but some of my power tools that are mains operated (120 VAC 60Hz) may not operate well on a square wave and I am not about to try the microwave oven.It depends on the device and each one is different. Some might work, but no doubt others will be compromised.
Many off-line switching power supplies have power factor correcting front ends, and these care very much about the shape of the input voltage waveform. In this type of supply the bulk capacitor comes after the boost converter stage. The boost converter is relatively complex, as it shapes the input current to track the input voltage while maintaining a constant output voltage. The control loop bandwidth is not wide enough to handle the fast edge of a square wave.But do not forget that every off-line smps has a bridge rectifier and 400V bulk capacitor at the input. So who cares if the input voltage is a sine wave or square wave?
Thanks!! Mr. Young!!! It's a very clear answer for my question.I don't know about TV's. I know for sure that PC's today use line switching power supplies, and the first thing that they do is rectify the line voltage into high voltage DC. They will work fine off a square wave, modified sine, or even high voltage DC *. Every brick-type computer supply I've seen is the same way, as are the tiny, light phone chargers. Only the older "wall wort" adapters actually have a line transformer in them, and you can usually tell those simply by their heavier weight for their size.
I have heard, but have not personally verified, that AC motors will not run well off a square wave - that they can overheat, draw more power than expected, or even burn out.
* With the exception that if the supply uses discrete rectifiers for a full wave bridge, only two of the parts will carry the current, and could over heat if the supply is pushed to the extreme limit.
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