The initial step in utilizing AC voltage from the city grid involves adjusting it to the desired level through a transformer. This process precedes the utilization of a rectifier circuit to convert the voltage into DC. Rectifier circuits are categorized into two types: half-wave and full-wave. The half-wave rectifier, while operational, does not suffice for a high-quality power supply design due to its low and pulsed output voltage. To design an efficient power supply, the full-wave rectifier circuit, specifically the bridge type or midpoint type, must be employed. Figure 1.2 illustrates a typical bridge-type rectifier circuit along with the waveform obtained from its output.
The signal waveform obtained from the rectifier output deviates significantly from the DC mark and includes multiple ripples. To reduce these fluctuations and attain a nearly constant DC voltage, filter circuits are employed. Different types of filter circuits, such as RC, C, LC, etc., exist.
Among these, capacitors offer the most practical and cost-effective filtration. Figure 1.3 visually depicts the signal and filtering process from the rectifier output. We won’t delve deeply into the workings and characteristics of the rectifier and filter circuits here. It’s presumed that you are familiar with these concepts beforehand.
Lastly, in figure 1.4, a sophisticated DC power supply circuit is presented, showcasing both the output signal waveform and its potential DC value. The capacitance of the capacitor employed for outlet filtering plays a crucial role. Opting for a capacitor with higher capacitance yields superior outcomes.
Applications and Uses of RectifiersThe primary application of the rectifier is to derive DC power from AC power. Rectifiers are used inside the power supplies of almost all electronic equipment. In power supplies, the rectifier is normally placed in series following the transformer, a smoothing filter, and possibly a voltage regulator. Below, we have discussed a few rectifier applications:
- Power Supplies:
- Rectifier and filter circuits are fundamental components of power supplies used in various electronic devices, including computers, televisions, and radios.
- Battery Chargers:
- Rectifiers convert AC from the mains to DC, and filter circuits ensure the charging current is smooth, enabling the charging of batteries for devices like smartphones and laptops.
- Power Inverters:
- Inverters convert DC power from batteries or solar panels into AC power for running household appliances during power outages or in off-grid situations.
- Welding Machines:
- Rectifier circuits are used in welding machines to convert AC power to DC power, providing a stable welding current.
- Electroplating and Anodizing:
- Rectifiers are utilized in electroplating and anodizing processes where controlled DC current is required for depositing metal or creating oxide layers on surfaces.
- Motor Drives:
- Rectifier and filter circuits are used in variable frequency drives to convert AC power to DC and then vary the frequency and voltage to control the speed of AC motors.