| 摘要 |
<p>The power supply apparatus serves to convert an electric direct voltage, acting as an input voltage, into an output voltage and comprises positive and negative input terminals (1, 3) which are arranged to receive the input voltage. The power supply apparatus also comprises a first series connection (7) of, at least a first coil (9) and a controllable switching element (11), which series connection interconnects the input terminals (1, 3), and a limiter circuit (29) which comprises a first capacitor (31) and a second series connection (33) of at least a second coil (35), a first rectifier element (37) and a second rectifier element (39), said second series connection being connected parallel to the first series connection in such a manner that the cathodes of the first and second rectifier elements are oriented towards the positive input terminal (1), one electrode of the first capacitor being connected to the anode of the second rectifier element and its other electrode to the junction (43) of the first coil and the switching element. The second series connection (33) also comprises an auxiliary voltage source (55) which is arranged to supply a direct voltage amounting to approximately half the input voltage and whose positive pole is oriented towards the positive input terminal (1). The presence of the auxiliary voltage source (55) prevents that upon switching off of the switching element (11) a voltage jump occurs across the switching element, which jump could cause an undesirably high energy dissipation in the switching element and also a disturbance (EMI).</p> |
