What Is a Rectifier and What Does It Do?
A rectifier, also known as a current rectifier;
Devices that convert AC current into DC current with the help of one or more diodes are called rectifiers.
In addition, since rectifiers straighten the current, they are also known as current rectifiers.
Rectifiers are generally used in energy backup applications, in some electronic devices and in power supplies.
In addition to battery charging operations, rectifiers are also used in industrial applications.
To go into detail, they are used in electrolysis processes, DC lighting units, welding machines, DC motor supply and the telecom sector.
What is the working principle of a rectifier?
In the most basic terms, rectifiers consist of diodes; a diode is a semiconductor circuit element that allows electric current to flow in only one direction.
When positive voltage is applied to the anode of the diode, current flow is enabled. When voltage is applied in the opposite direction, it resists the current and does not let it pass.
There are two types of current: AC and DC. AC is alternating current and has a wave form. Therefore, AC current is a current that fluctuates over time. DC current, on the other hand, is direct current, that is, constant current, and does not oscillate.
When AC current is fed to a diode, the diode only allows current to pass in the positive direction, so it blocks the negative oscillations of the alternating current and thus rectifies the alternating current. As a result, DC current is produced.
When one diode is added to the circuit, a half-wave rectifier is formed; for a full-wave rectifier, two diodes are used and a smooth rectification is achieved.
What are the control types of battery charging rectifiers?
Battery charging rectifiers come in thyristor-controlled, variac-controlled, MOSFET-controlled (SMPS type) or uncontrolled diode-only rectifying varieties.
Working Principle of the Variac-Controlled Battery Charging Rectifier
In the variac-controlled battery charging rectifier, the output voltage is controlled with the help of a variac, ensuring that the output voltage remains stable.
Variac-controlled rectifiers are not widely preferred as they are heavy and bulky.
Working Principle of the Thyristor-Controlled Rectifier
Thyristor-controlled rectifiers are more widely preferred because they deliver higher-quality output than other rectifiers.
Since the DC current they deliver is of higher quality, batteries connected to a thyristor rectifier have a longer service life.
Likewise, devices connected to thyristor-controlled rectifiers operate more efficiently and last longer. In this type of rectifier, an Electronic Control board continuously monitors the output voltage and current, and the desired DC voltage is obtained by triggering the thyristors at the appropriate angle.
Working Principle of the Diode Rectifier
It is widely used on the market due to its low cost. Diode rectifiers consist of a transformer and a bridge diode. The output voltage is affected by mains voltage fluctuations or load changes. Since the output voltage is constantly variable, they pose a risk for the devices and batteries to be connected.
What should an advanced rectifier be like?
Rectifiers operating on the Constant Voltage and Constant Current principle are the most preferred. The sophistication of a rectifier is shown by the adjustability of its output values.
In an advanced rectifier device, the output voltage, output current, fast charge voltage and fast charge time can be adjusted. In addition, an advanced rectifier should have overheating, short circuit and overvoltage protections.
These points are important for rectifier safety. For this reason, microprocessor-controlled rectifiers should be preferred for use in sensitive and vitally important systems.
On the market, rectifier models are produced with three-phase and single-phase inputs and with 12 VDC, 24 VDC, 48 VDC, 110 VDC and 220 VDC rectifier outputs.
The standard output capacities of rectifiers are 10, 25, 50, 100 and 200 amperes.