CIRCUIT ARRANGEMENT FOR THE REGISTRATION OF THE CHARGE CURRENT OF A REVERSIBLE D. C. CHOPPER

摘要

In a reversible d-c controller, a current transformer having two primary windings as current measuring sensors is provided for determining the load current. The primary windings are connected with opposite winding sense into two diagonally disposed bridge arms of a controller bridge circuit. The secondary winding of the current transformer is coupled through a full wave rectifier and across a load resistor to the input of a sample-and-hold stage which is provided with an electronic sampling switch and at the output of which a signal proportional to the actual value of the load current is present. The bridge circuit comprises 4 bridge arms, each bridge arm having an electronic switch and a reverse biased diode shunted across the switch. Each pair of bridge arms connected to the same side of the power supply buss and coupled across the load form a bypass circuit. In order to evaluate the load current, the sampling switch is closed for a predetermined time whenever the load current circulates in a bypass circuit.