Current controlled end stage for electromagnetic drives, esp. for proportional magnets used as valve drive

摘要

The end stage determines the control magnitude actual value of a current through a magnetic coil of the drive, and applies to the coil a clocked voltage of specified clock pulse ratio. Between the earth-side switch (3) and the magnetic coil (1) is located a second measuring resistor (17), the first one (4) coupling the coil to earth. To the series circuit of the switch, the second measuring resistor, and the magnetic coil is parallel-connected a first diode (6), while a second diode (5) is parallel-connected to the series-connection of a switch (2), coupled to the supply voltage (Uv), and the magnetic coil. If the two switches are simultaneously actuated, the amount of voltage drop at the first measuring resistor is applied to the actual value input of the current control (10) as a rate of the current flowing through the magnetic coil.