Improved active current sampling circuit

Abstract

The invention provides an improved active current sampling circuit. The circuit comprises a center tap transformer, a current transformer, an active current sampling resistor, a half-wave rectification circuit, polarized filter capacitors and a filter capacitor protection diode; after generators are connected in parallel, the center tap transformer reduces and isolates alternating current connected to a primary winding, and then two modulation voltages with the same voltage absolute value and opposite phases are formed at the two ends, opposite to the center tap, of a secondary winding; activecurrent is converted into a voltage signal U16 after passing through a sampling resistor R16, the voltage signal U16 is superposed with two modulation voltages of the secondary winding of the centertap transformer, the two superposed voltages are respectively subjected to half-wave rectification and then are filtered by a polar filter capacitor, and voltage Uab reflecting the magnitude and polarity of the active current is obtained. The cathodes of the two polarized filter capacitors are in butt joint for use, each polarized filter capacitor is connected with the filter capacitor protectiondiode in parallel, and the reverse voltage value of the polarized filter capacitors is clamped within a reverse withstand voltage index.

Description

technical field [0001] The invention belongs to the field of aviation electrics and relates to an improved active current sampling circuit. Background technique [0002] On a multi-engine aircraft, there are generally multiple alternators installed. The aircraft AC power system composed of multiple alternators can run in parallel. After the AC power system is connected in parallel, due to the differences in factors such as manufacturing process, working environment and working status, there will be an unbalanced distribution of active load of each generator when working in parallel. In order to make full use of the system capacity and distribute the active load in a balanced manner, an automatic active load balancing device must be installed in the parallel system. [0003] At present, after the constant speed and constant frequency AC power system driven by the constant speed transmission device is connected in parallel, the active current sampling circuit in the system c...

AI Technical Summary

Problems solved by technology

Filtering after rectification generally uses polarized capacitor filtering, but after the rectified voltage of the active current sampling circuit is compared with the active voltage of another product connected in parallel, the positive and negative DC voltage output by the rectification filter changes. At this time Polarized filter capacitors will withstand back pressure, and polarized capacitors have a very low backpressure resistance (generally no more than 1V), so polarized capacitors are extremely easy to damage; for this problem, some active current sampling circuits Non-polar capacitors will be used for filtering, but non-polar capacitors are large in size, heavy in weight, small in capacitance, poor in filtering effect, and cannot meet the requirements of aviation power supplies

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