| 摘要 |
<p>A dc-dc converter employs both half-bridge topology and current-mode switching control. The controller operates by sensing the current (1s) that flows through the transformer (T) that is interposed between the node (13) of two series switches (S11Sz) and the node (14) between the two split capacitors (C11C2). The controller develops gating signals to close and open the switches based on the rise of current to a predetermined command level (Vref). A gate signal for the second switch (S2) which is developed between actuations of the first switch (S1) , has its pulse width made equal to the period that the first switch was closed. This maintains a balanced voltage-time product, so that the series or split capacitors (C11C2) remain in balance. The controller (21) can include a sample gating circuit with a comparator (27) that receives the current sample signal and the command level. The track side signal which develops the gating pulse for the other switch can be developed with analog circuitry, i.e. by charging a capacitor (35), or else digitally, i.e. in clock pulse counters (51,53). <IMAGE></p> |
