| 摘要 |
A resonant converter comprises switching circuitry (1) for supplying pulses, at a controllable frequency, to a resonant circuit so as to power the primary circuit (3, 12) of a transformer (4). The secondary winding (5a, 5b) of the transformer (4) delivers an AC signal which is rectified and then produces a load current. On the primary side, the converter has a resistor (13) for deriving a first electrical signal representative of the current in the primary circuit (3, 12), and an auxiliary winding (14) which is closely coupled to the secondary winding (5a, 5b) and across which an auxiliary voltage is induced as a consequence of the close coupling of the winding (14) to the secondary winding (5a, 5b). A resistor/capacitor combination (16, 17) integrates the auxiliary voltage with respect to time to derive a second electrical signal. Computational circuitry (19) combines the first and second signals so as effectively to subtract the second signal from the first signal to derive a difference signal which is representative of the load current reflected onto the primary side of the transformer (4) and is accordingly representative of the actual load current. |
