Pwm ac to dc converter

Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search. It uses a flyback transformer. This is the charger:. By taking a look at the datasheet's controller I found out the circuit is different than a smoothed rectifier with the output connected to a buck converter.

The typical application of the IC shows connections to a transformer winding and to an optcoupler. The display showed 2V,then the valued changed to 0V, then it changed again to 2V and so on. The time period was approximately 1s.

This resembled a square wave. These power adapters there is no battery charging circuit! The transformer also gives one additional but crucial benefit: isolation. The transformer isolates the low voltage output from the mains voltage at the input.

You do not what to get an electric shock every time you pick up your phone while it is charging now do you? That is why isolation is needed. It prevents current "escaping" from the mains and returing to earth through your body. Some means is needed to monitor the output voltage often 5V and adjust the mains-side swithing using a feedback loop.

This measuring is where the opto coupler comes in, it feeds back information about the output voltage to the chip. Using an optocoupler means that this is also isolated. In some other designs the feedback is done via the transformer but often this is less accurate than using an optocoupler.

You should not draw any conclusions about the response of your multimeter while it is on VAC. Depending on the implementation of the multimeter's circuits it might display 0 zero or anything else. You cannot conclude that the power adapter outputs a square wave just because your multimeter seems to think so.

Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Learn more. Asked 5 years ago. Active 5 years ago. Viewed times. There may be more ways to make what I'm speaking about, so I'll try to narrow the list down. This is the charger: By taking a look at the datasheet's controller I found out the circuit is different than a smoothed rectifier with the output connected to a buck converter.

How does this kind of topology, the one used for this charger, work using PWM? Community Bot 1. Daniel Tork Daniel Tork 1, 15 15 silver badges 33 33 bronze badges.

The DC voltage is back to V within 1. We can see that the DC voltage drops to V. A drastic change in the primary current waveform can also be observed.

When the pulses are blocked, the Three-Level Bridge block operation becomes similar to a three-phase diode bridge. If you modify this model, or change parameter values of power components, the initial conditions stored in the "xInit" variable will no longer be valid and Simulink will issue an error message.

To regenerate the initial conditions for your modified model, follow the steps listed below:. Double click on the Breaker block and temporarily disable the breaker closing by multiplying the "Switching time s " parameter by Temporarily disable pulse blocking by multiplying the " Time s " parameter by Change the Simulation Stop Time to 0. Note that in order to generate initial conditions coherent with the 60 Hz voltage source phase angle, the Stop Time must an integer number of 60 Hz cycles.

Start simulation. The final states which have been saved in the "xFinal" structure with time can be used as initial states for future simulations. Double click on the Breaker block and reset the "Switching time s " parameter back to 0.

Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select:. Select the China site in Chinese or English for best site performance.