The electromagnetic noise generated when the electronic ballast works conducts to the power grid by the input power cord, causes conduction disturbances, causes pollution on surrounding electromagnetic environment and affect the normal operation of other electronic devices or systems in the environment. The electromagnetic interference of electronic ballasts is mainly from the following aspects:
1) The inherent noise of components, including thermal noise, shot noise, and contact noise.
2) The electromagnetic noise generated by semiconductor diode during switching. The voltage and current changed instantaneously will form a strong electromagnetic noise, , while turn-on and turn-off quickly.
3) Power semiconductor devices will produce a large transient voltages or currents and cause parasitic oscillations in the switching process. The higher the switching frequency, the higher the switching current, and the greater the transient electromagnetic noise caused by. The conducted interference produced by semiconductor devices on the AC grid is the main source of conducted interference, which is divided into differential mode and common mode noise.
4) In the passive power factor correction circuit using high-frequency pump or double pump, the high-frequency switching signal of power switch applied to the input through the feedback element, go through the power line and go into the grid to form a conduction disturbances.