With the exception of simple battery powered devices, just about all electronic equipment requires power conversion solutions. In normal circuitry, the operation is via DC voltage sources and the power delivery to the system in AC. Magic? I think not. This is the work of power conversion solutions.
In the event that the system being powered uses DC power, there is no need for conversion although some advanced power conversion solutions may be needed to step up or step down the DC power to the exact voltage required by the system.
Linear Regulation and Switching Power
Linear regulation is achieved with one or several semiconductors. Linear regulation power supplies basically convert AC to DC to achieve functions like filtering and isolation. Linear regulation power supplies have an input voltage range of about +/- 10, which has a direct effect on the efficiency of the power supply.
On the other hand, switch-mode involves rapidly switching between on and off states of several semiconductors for voltage conversion.
Switch-mode is the more popular power conversion solution of the two, owing to the high efficiency and high-power density it offers. The output ripple is a lot higher than in linear regulation. This is because of the propagation of the higher frequency used.
As good as this is, it doesn’t bode well in low noise applications like instrumentation. You can subvert these shortcomings with output filtering circuitry. Switch-mode power supplies also have slower transient recovery times than linear power supplies but with longer output holdup times.
There is no problem of the input voltage having any effect with the efficiency of the power supply. The input range is usually 50-100% by use of universal line controls.
Up and Down Conversion
Regardless of whether you are dealing with indoor power supply, outdoor power supply, or any other type of power supply, the relationship between the input and output voltage determines if it’s up or down conversion. Outdoor power supply systems simply are rugged enough systems that can provide stable power for long periods of time under non-ideal conditions.
If the output voltage is lower than the input voltage, then the topology is referred to as down conversion. Down conversion also answers to ‘buck’.
If the output voltage is higher than the input voltage, the topology now becomes up conversion. Up conversion can also be referred to as ‘boost’.
Types of Power Converters
A power converter basically is a power conversion solution that converts electrical energy from one form into another. Here are the forms I speak of:
- AC to DC
- DC to DC
- DC to different DC voltage
- AC to different AC voltage
The converter also acts as a link to the power source and power supply output. Let’s dive right in to the converter types:
These converters convert alternating current to a direct, one directional current. The voltage needs to be in the operational range for the DC supply so a step-down or step-up transformer is needed.
The conversion of AC to DC is referred to as rectification and the converter itself can be referred to as a rectifier. The sinusoidal waveform of AC is converted into a series of positive peaks synonymous with DC supply by a series of diodes.
This conversion is not as common as the former and involves an inverter converting direct, one-directional current into an alternating, reversing current.
A couple of configurations can be tried out to achieve DC-AC conversion with one method being using an oscillator and a step-up transformer. An oscillator is an electronic circuit that uses transistors and other semiconductors to generate an alternating signal from a small DC voltage. If the output still doesn’t match the desired voltage, a step-up transformer can be used.
DC-DC converters are needed when you need to convert DC current to another voltage still of DC type.
These devices convert AC in one waveform to another using some advanced power conversion solutions like thyristors. The output voltage and frequency are managed with regard to the device’s usage and requirements.