1986 Volume 70 Issue 10 Pages 531-536
Numerical calculation is made for a transistor inverter which is suitable for discharge lamp ballast. The inverter is composed of a power transistor, two inductors, two capacitors, a diode and a trigger unit which drives the power transistor.
Power delivered to the load, distortion of the output waveform and peak voltage across the power transistor are calculated. Following results are obtained where f0=1/2π√L2C2, R0=√L2/C2 and RL is lamp resistance (lamp voltage divided by lamp current).
(1) Drive frequency f must be equal to or higher than f0.
(2) The power depends strongly on f/f0 and RL/R0, and weakly on L1/L2 and C1/C2.
(3) With small value of RL/R0(≅0.1), the output waveform is almost sinusnoidol. Increasing RL/R0 results large distortion in the output waveform.
(4) Peak voltage on the power transistor depeds on L1/L2 and /C2, and weakly on f/f0 and RL/R0.
These results are useful for designing the discharge lamp ballast and a procedure to determine the values of L1, L2, C1 and C2 is described.