Measurement method and measurement device for a DC actuator

摘要

In the case of this measurement method for detecting the load current of a DC actuator, a current measurement resistor (R1) is arranged between a main connection of an electronic switch (S1) and that terminal (2) of a DC voltage source (1) which is also connected to the control device of the actuator. During the ON phases of the electronic switch (S1), the voltage (U2) representing the actual current value is picked off the current measurement resistor (R1) via a second electronic switch (S2), which is controlled in synchronism with the first switch (S1), and said voltage is supplied to the control device. At the same time, a capacitor (C1) is charged to this voltage level (U2). During the OFF phases of the switches (S1, S2), the voltage level (U2), which is stored with the aid of the capacitor (C1) is used for simulation of the load current behaviour in the freewheeling phase. In consequence, a gap in the voltage (U2) representing the actual current value during the OFF phases is prevented. Preferred fields of application of the invention are battery chargers for electric cars and motor controllers. <IMAGE>