| 摘要 |
In a flow inverter with several output voltages and subsidiary current control (current mode control), the sum of the flows through the storage choke is detected by measuring the transformer current (ip) on the primary side. In this primary current measurement that part of the signal must be suppressed which corresponds to the reverse currents (iR) of the free-wheeling diodes (D2, D4). To this end, a time-variant filter (V2, R4, C3) consisting of the series connection of a switching arrangement and a first-order linear low-pass is fitted on the secondary side of the flow inverter. By means of a differential component (C4, R5), the switching arrangement of the time-variant filter (V2, R4, C3) is conductively controlled throughout the blocking delay time of the free-wheeling diodes (D2, D4) and thus suppresses the signal component in the detection of the actual value of the current arising from the reverse currents (iR). At the end of the blocking delay time, the information on the choke flow may be taken via the linear low-pass to the pulse width modulator which controls the on/off ratio of the power switch on the primary side in the conventional manner. |
