solid state relay purchase XSSR-DA4840
The power switch is to use the circuit to control the switch tube for high-speed channel connection and cut-off. The direct current is transformed into high-frequency alternating current and supplied to the transformer for voltage transformation, so as to produce one or more groups of voltages required!
Function of power switch
1. DC input through rectifier; 2. The switch tube is controlled by high-frequency PWM (pulse width modulation) signal, and the DC is added to the primary of the switching transformer; 3. High frequency voltage is induced from the secondary of the switching transformer and supplied to the load through rectification and filtering; 4. The output part is fed back to the control circuit through a certain circuit to control the PWM duty cycle, so as to achieve the purpose of stable output.
There is a door in the power switch. The power will pass as soon as the door is opened, and the power will stop as soon as the door is closed. So what is the door? Some power switches use thyristors, and some use switching tubes. The performance of these two components is similar. They are turned on and off by adding pulse signals to the base electrode, (switching tube) control electrode (thyristor). The pulse signal is coming in half a week, and the voltage on the control electrode rises, The switch tube or thyristor is turned on, and the 300V voltage output after 220V rectification and filtering is turned on, which is transmitted to the secondary through the switching transformer, and then the voltage is increased or reduced through the transformation ratio for the work of each circuit. When the negative half cycle of the oscillation pulse comes, the voltage of the base of the power regulating tube or the control electrode of the thyristor is lower than the original set voltage, the power regulating tube is cut off, the 300V power supply is turned off, and the secondary voltage of the switching transformer is not available. At this time, the working voltage required by each circuit is maintained by the discharge of the filter capacitor after the secondary circuit is rectified. When the positive half cycle signal of the next pulse comes, repeat the previous process. This switching transformer is called high frequency transformer because its working frequency is higher than 50 Hz low frequency. Then, how to obtain the pulse to push the switch or thyristor? This requires an oscillation circuit. We know that the crystal triode has a characteristic, that is, the voltage between the base and the emitter is 0.65-0.7v, which is the amplified state, more than 0.7V is the saturated conduction state, and - 0.1v-0.3v works in the oscillation state. After its working point is adjusted, it relies on deep negative feedback to generate negative pressure to make the oscillation tube vibrate, The frequency of the oscillation tube is determined by the charging and discharging time of the capacitor on the base. When the oscillation frequency is high, the output pulse amplitude is large, otherwise it is small, which determines the output voltage of the power adjustment tube.