The working principle, characteristics, and classification of electroplating rectifiers
1、 Working principle of electroplating rectifier
Apply voltage to the PN junction, that is, P-junction positive voltage and N-junction negative voltage. The current flows from the P junction to the N junction side, and holes and electrons move towards the interface, narrowing the space charge region, allowing the current to pass smoothly and conducting. If the N junction is connected to the positive electrode of the voltage and the P junction is connected to the loss electrode, the holes and electrons will move away from the interface, widening the space charge region, and the current will not flow, causing it to be cut off. This is the unidirectional conductivity of PN junctions. By utilizing this characteristic, forward voltage can be turned on and reverse voltage can be turned off, thereby completing the rectification of alternating current.
2、 Characteristics of Electroplating Rectifiers
1. Small size and light weight
The volume and weight are 1/5-1/10 of that of a thyristor electroplating rectifier, making it convenient for you to plan, expand, move, protect, and install.
2. Good energy-saving effect
Due to the use of high-frequency transformers in the switching power supply, the conversion power is greatly increased. In general, the power is more than 10% higher than that of thyristor devices, and it is more controllable when the load rate is below 70%. Silicon equipment improves efficiency by more than 30%.
3. High output stability
Due to its fast response speed (microsecond level) and strong adaptability to network power and load changes, the output accuracy can be better than 1%. The working efficiency of switching power supply is high, therefore the control accuracy is high, which is conducive to improving product quality.
4. The output waveform is easy to modulate
Due to its high working frequency, the processing cost of adjusting the output waveform is relatively low, making it easy to change the output waveform according to the user's process requirements. This has a strong effect on improving work efficiency on the job site and improving the quality of processed products.
3、 Classification of electroplating rectifiers
Electroplating rectifiers can be divided into thyristor power supplies (commonly known as silicon rectifiers) and high-frequency switching rectifiers (also known as switching power supplies).
Thyristor power supply (commonly known as silicon rectification): It uses a power frequency transformer to convert the AC input voltage into a lower (IOV~20V) AC voltage, and then stabilizes the voltage through thyristor rectification. The control mechanism controls the conduction angle of the thyristor through a control circuit to adjust the output voltage and current. The disadvantages of this power supply are its large size, heavy weight, high noise, high power consumption, and large ripple. With the increasing demand for coating quality and automatic control in the production process, as well as the increasing awareness of energy conservation and environmental protection among people in recent years, it has gradually been screened in PCB electroplating. Mainly used for high current industrial electroplating.
High frequency switching rectifier (also known as switching power supply): It directly rectifies and filters the AC power grid through EMI anti electromagnetic interference line filters, and converts the DC voltage into high frequencies of tens or hundreds of kHz through a converter. The frequency square wave is blocked by a high-frequency transformer, reduced in voltage, and then output DC voltage through high-frequency filtering. After sampling, comparing, amplifying, controlling and driving circuits, the duty cycle of the power transistor in the converter is controlled to obtain a stable output voltage (or output current).
