Most everything we use of convenience and need these days is electrically powered. Most often we have access to a source of voltage at one, or maybe two particular values. Unfortunately in many cases the very items we use and need internally have components that do not run at the voltages available to us.
Many of the important electronics, such as BJT’s, FET’s and decision making items such as microprocessors actually run, or are biased with, lower level DC voltages…
So how do you get the lower DC voltages needed from a higher available AC voltage? This is known as AC to DC conversion and the process involves voltage transformation, rectification, and filtering….
Voltage transformation is what we here at CET specialize in. Our products cover a wide range of power levels, voltage levels as well as spanning great ranges in frequency with a multitude of interfacing options.
At low frequency, the best choice of core material is known as the silicon-steel core. These cores are highly permeable and act to channel lines of magnetic flux. The flux is what carries the energy from the primary side to the secondary side. When lines of flux break over a wire they induce a voltage. If your secondary has more wires or windings than your primary, the voltage induced will be greater than that applied at the primary. Likewise, if your secondary has fewer windings than your primary, the voltage induced will be lower than the applied primary voltage.
Once a voltage is transformed from something higher to something lower it is then rectified, often by what is known as a bridge rectifier and then filtered to yield a smooth DC voltage. This is an easy process but it is not an efficient process.
A more efficient process is to first rectify and filter your line voltage. Then using a chipset and a FET for instance, you can quickly switch, by turning on and then off, the DC voltage into the primary side of a switching transformer. The output voltage of your switching transformer is still a function of the turns ratio but it is also a function of what is known as the duty cycle. The duty cycle is how long per switching period the voltage is applied with respect to the total switching period.
A higher frequency switching transformer allows for more power to be delivered in a given unit of time for the same input voltage. It’s like trying to move a box across a room by periodically pushing it. The more often you push it with the same force the quicker it gets to the other side and the greater the power you are using. The energy used is the same though. Power is the rate of energy used per unit time and this is
why the power is more while the energy used is the same.
High frequency switching transformers are often smaller, lighter and more efficient than low frequency silicon-steel transformers. Much of this is because when the load is not consuming power the duty cycle can be made low enough to just keep the output voltage level. It’s a “use it when you need it” type process.
Whatever the route you choose to take, when a lower voltage is required, be it AC or DC, having only a higher level AC voltage available, a transformer of some kind is required in the voltage transformation process.
Please reach out to us here at CET if you have such a requirement. We have been designing and manufacturing transformers of all kinds for decades. We have the expertise to get you what you need and with US based sales and engineering support, we’ll always be nearby to answer any questions you may have.
