Abstract:
This thesis proposes a new high power-factor and high efficiency singlestage electronic ballast for fluorescent lamp. The proposed electronic ballast is modified from single-stage class D electronic ballast having efficiency of 89.4 percent at full load. This thesis is included capacitor parallel with each power switch and set the circuit parameter to operate under class DE inverter condition. By using this proposed method the DC bus voltage can be reduced approximately 50 percent compared with conventional class D inverter circuit. Due to the operation of power switch at zero voltage switching condition and low dv/dt of class DE switching, less power loss can be obtained. To verify the theoretical derivation, a prototype circuit with the switching frequency of 62 kHz, the constant duty cycle of 25 percent, 110 volt input voltage are designed and constructed. The experimental results show that the efficiency of the prototype ballast increase to 93 percent at full load.