Encender 3 LEDs con fuente trifásica regulable de 24V

jmromerocastellano wrote:

enceder 3 leds con una fuenter trifasica de 24v regulable

To power 3 LEDs using a 24V adjustable three-phase power supply, there are several important considerations and steps to follow. Here's a comprehensive guide:

1. Understanding the Power Supply
- Three-phase power: A three-phase power supply typically provides three AC voltages, each 120° out of phase with the others. However, LEDs require DC (direct current) to operate. Therefore, you will need to rectify the AC output to DC before powering the LEDs.
- Adjustable voltage: Since your power supply is adjustable, you can regulate the output voltage, but you must ensure that the voltage is appropriate for the LEDs and the current-limiting components.

2. LED Characteristics
- Forward voltage (Vf): LEDs typically have a forward voltage between 2V and 3.6V, depending on the color and type. For example, red LEDs usually have a Vf of around 2V, while blue or white LEDs may have a Vf of around 3.3V.
- Current requirements: Most standard LEDs operate at a forward current of around 20mA. Exceeding this current can damage the LEDs, so current limiting is essential.

3. Rectifying the Three-Phase Power
- To convert the three-phase AC to DC, you can use a three-phase bridge rectifier. This will provide a DC voltage that can be used to power the LEDs.
- After rectification, the DC voltage will be higher than the AC RMS voltage. For example, if your three-phase supply is 24V AC, the rectified DC voltage will be approximately 33.9V (24V * √2).

4. Current Limiting for LEDs
- Resistor-based current limiting: The simplest way to limit the current through the LEDs is by using resistors. The value of the resistor can be calculated using Ohm's law:
$$ R = \frac{V_{\text{source}} - V_{\text{LED}}}{I_{\text{LED}}} $$
Where:
- $V_{\text{source}}$ is the rectified DC voltage (e.g., 33.9V),
- $V_{\text{LED}}$ is the forward voltage of the LED (e.g., 2V for red LEDs),
- $I_{\text{LED}}$ is the desired current (e.g., 20mA or 0.02A).

Example: For a red LED with a forward voltage of 2V and a desired current of 20mA, the resistor value would be:
$$ R = \frac{33.9V - 2V}{0.02A} = 1595 \, \Omega $$
You can use a standard resistor value of 1.6kΩ.

5. LED Configuration
- Series connection: You can connect the LEDs in series, which means the total forward voltage will be the sum of the individual LED voltages. For example, if each LED has a forward voltage of 2V, the total forward voltage for 3 LEDs in series will be 6V. The resistor value will need to account for this total forward voltage.
- Parallel connection: If you connect the LEDs in parallel, each LED will need its own current-limiting resistor. The voltage across each LED will be the same, but the current will be divided among the branches.

6. Using a Constant Current LED Driver
- A more efficient and reliable solution is to use a constant current LED driver. These drivers regulate the current through the LEDs, ensuring consistent brightness and protecting the LEDs from overcurrent. They can also handle higher input voltages, making them ideal for use with a rectified 24V three-phase supply.
- Advantages: Constant current drivers are more efficient than resistors, provide better control over the LED brightness, and protect against voltage fluctuations.

7. Safety Considerations
- Isolation: Ensure proper isolation between the high-voltage AC side and the low-voltage DC side. Use optoisolators or other isolation methods if necessary.
- Heat dissipation: Resistors and other components may dissipate heat, so ensure adequate ventilation or heat sinking.
- Voltage regulation: If your power supply voltage fluctuates, consider using a voltage regulator or a constant current driver to maintain stable operation.

8. Step-by-Step Implementation
1. Rectify the three-phase AC: Use a three-phase bridge rectifier to convert the AC to DC.
2. Smooth the DC output: Optionally, add a smoothing capacitor to reduce ripple in the DC voltage.
3. Calculate and add current-limiting resistors: Based on the rectified voltage and the LED forward voltage, calculate the appropriate resistor values.
4. Connect the LEDs: Wire the LEDs in series or parallel, depending on your design.
5. Test the circuit: Adjust the power supply voltage and verify that the LEDs are operating within their specified current limits.

9. Alternative Approach
- If you are working with a larger-scale or industrial application, consider using LED drivers designed for three-phase power supplies. These drivers are specifically built to handle the power conversion and provide efficient, safe operation for LED lighting systems.

Conclusion
To power 3 LEDs with a 24V adjustable three-phase power supply, you need to rectify the AC to DC, calculate appropriate current-limiting resistors, and ensure proper safety measures. For more efficient and reliable operation, consider using constant current LED drivers. Always ensure that the voltage and current are within the safe operating limits of the LEDs to avoid damage.