DIAGRAMA DE BLOQUES

DIAGRAMA DE BLOQUES

For the realization of this project, a block digram of each stage of the process, which was designed describre below:

• Transform and rectify the AC signal

At this stage a transformer transforms through the mains input 120V AC output signal to a 6V AC, it works with a low voltage because the circuto is not necessary to work with high voltages. After the signal tranform full wave rectification is applied through two diodes, since the transformer is to be considered for use with center tap. Due to the connection in the center of the secondary winding, the circuit is equivalent to two half-wave rectifiers.

Two diodes rectification works of sigueinte way: The upper rectifier operates with the positive half cycle of the voltage in the secondary, while the lower rectifier operates on the negative half cycle of voltage on the secondary. That is, D1 conducts during the positive half cycle, and D2 conducts during the negative half cycle. Thus the rectified load current flowing during the two half cycles.

• zero crossing detector stage

Here at this stage the rectified signal changes from positive to negative or vice versa. in this case the zero-crossing detector will allow adjusting the power level of electrical energy, can also be defined as the point where the instantaneous voltage is zero. Changing the sign transition of a signal is detected. Ideally, provides a small pulse which coincides with the time queel alternating signal voltage is zero.

• Sawtooth generator

The third stage corresponds to a sawtooth generator, comprising a transistor, a resistance which is responsible for charging the capacitor linearly through the collector of the transistor. The pulses from the zero crossing detector bias transistor, allowing the discharge of the capacitor. Once leaving the transistor, the capacitor is charged through the resistance gradually. Loading and unloading is what made the formation of the sawtooth.

• PWM stage

At this stage, the sawtooth is compared with a DC signal from a voltage divider to generate the pulses to control the intensity of the light bulb. This stage operates similarly to stage zero crossing detector means.

• Power stage

Finally in the fifth step, the above signals enter an optocoupler, a device driver with an optically isolated triac, this device contains a diode and a silicon bilateral switch activated light emitter, functioning as TRIAC. It is designed for the connection between electronic controls and power TRIAC control resistive and inductive loads for 240 VAC operation. This circuit is responsible for giving the power to the final implementation of this case is used to trigger a triac.

THEORETICAL

...