Average Voltage Calculator

Average Voltage Formula:

\[ V_{avg} = \frac{V_{peak}}{\pi} \times (1 - \cos(\alpha)) \]

Average Voltage (V_avg):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Average Voltage?

Average voltage represents the DC equivalent value of an AC voltage waveform after rectification. For a half-wave rectified sine wave, it's calculated based on the peak voltage and firing angle of the thyristor or SCR.

2. How Does the Calculator Work?

The calculator uses the average voltage formula:

\[ V_{avg} = \frac{V_{peak}}{\pi} \times (1 - \cos(\alpha)) \]

Where:

\( V_{peak} \) — Peak voltage of the AC waveform (V)
\( \alpha \) — Firing angle in degrees (°)
\( \pi \) — Mathematical constant pi (approximately 3.1416)

Explanation: The formula calculates the average value of a half-wave rectified sine wave, where the firing angle α determines the portion of the waveform that is conducted.

3. Importance of Average Voltage Calculation

Details: Calculating average voltage is essential in power electronics for designing and analyzing rectifier circuits, motor speed controls, and power supplies. It helps determine the DC output from AC input after phase-controlled rectification.

4. Using the Calculator

Tips: Enter peak voltage in volts and firing angle in degrees (0-180°). The firing angle represents the delay in degrees from the zero-crossing point where the thyristor begins conduction.

5. Frequently Asked Questions (FAQ)

Q1: What is the range of valid firing angles?
A: For half-wave rectification, the firing angle typically ranges from 0° to 180°. At 0°, full conduction occurs, while at 180°, no conduction occurs.

Q2: How does firing angle affect average voltage?
A: As the firing angle increases, the conduction period decreases, resulting in lower average output voltage. The relationship follows a (1-cosα) pattern.

Q3: What is the maximum average voltage possible?
A: The maximum average voltage occurs at α = 0°, where V_avg = V_peak/π. For a standard 120V RMS supply (V_peak ≈ 170V), maximum V_avg ≈ 54V.

Q4: Does this formula work for full-wave rectification?
A: No, this formula is specifically for half-wave rectification. Full-wave rectification has a different formula: V_avg = (2×V_peak/π) × (1 + cosα).

Q5: What applications use phase-controlled rectification?
A: This technique is used in light dimmers, motor speed controls, battery chargers, and power supplies where variable DC output is required from AC input.