Thyristor dimming circuit with lossless discharging circuit and method thereof

摘要

Thyristor dimming circuits and methods are disclosed herein. In one embodiment, a thyristor dimming circuit can include: (i) a thyristor and a rectifier bridge configured to receive a sinusoidal AC voltage, and to generate a phase-loss input voltage; (ii) a power stage circuit configured to have the phase-loss input voltage applied thereto, the power stage circuit having a main switch and being configured to drive a lamp load through electrical conversion; and (iii) a discharging circuit configured, during a first predetermined time interval, to control the main switch to operate with a fixed duty cycle at a fixed frequency, where the first predetermined time interval begins prior to an absolute value of the sinusoidal AC voltage being reduced to zero, the first predetermined time interval ending when the phase-loss input voltage is again applied to the power stage circuit.

主权项

1. A thyristor dimming circuit, comprising:
a) a thyristor and a rectifier bridge configured to receive a sinusoidal AC voltage, and to generate a phase-loss input voltage; b) a power stage circuit configured to have said phase-loss input voltage applied thereto, said power stage circuit having a main switch and being configured to drive a lamp load through electrical conversion; and c) a discharging circuit configured, during a first predetermined time interval, to control said main switch to operate with a fixed duty cycle at a fixed frequency, wherein said first predetermined time interval begins prior to an absolute value of said sinusoidal AC voltage being reduced to zero, said first predetermined time interval ending when said phase-loss input voltage is again applied to said power stage circuit.