A method for controlling a magnetic valve and particularly a method for dispensing and/or aspirating a volume of liquid as well as a corresponding dispenser/pipetting apparatus is disclosed. The method for controlling a magnetic valve has measuring a capacitance at the magnetic valve and determining a position of a plunger based on the measured capacitance. The method for dispensing or aspirating a volume of liquid has controlling a flow of a system fluid by a magnetic valve located between a pressure source and a dispenser/pipetting tip, dispensing or aspirating a volume of liquid through an exterior opening of the tip dependent on the flow of the system fluid, wherein controlling the flow and determining a flow time in dependence of the volume of liquid to be dispensed or aspirated, and controlling the magnetic valve is held open for the duration of the flow time.

A method for determining a switching point of a solenoid valve. A solenoid coil is energized to raise a solenoid armature to unblock a flow opening. For a signal profile characteristic of a current profile in the solenoid coil, multiple periods each different from one another and each having the same predefined temporal length are determined. Within each period, a minimal and a maximal value of the signal profile and associated points in time are ascertained and a product of a difference between the maximal and minimal value and a difference between the associated points in time are ascertained. On the basis of the points in time of the minimal and maximal value of that period, which corresponds to a maximal value of the product, the switching point is determined.

The invention relates to an electromagnetic positioning device (10) having energizable stationary coil means (1), a magnetic guide element (2) associated thereto and having a core section (2a) and an anchor unit (3) moveable in relation to the guide element (2) and along an axial movement direction (L) as a reaction to an energization of the coil means (1), wherein the guide element (2) is a hollow cylinder that partially surrounds the anchor unit (3). The positioning device (10) has an ultra-wide-band sensor unit (4) which is preferably integrated in the guide element (3) and is designed for measuring the position and/or the displacement of the anchor unit (3) in the guide element (2).

Disclosed herein are reluctance actuators and methods for feedback control of their applied force. Embodiments of the reluctance actuators include an electromagnet positioned to deflect a metallic plate to provide a haptic output. The control of the force is provided without force sensors (sensorless control) by monitoring voltage and/or current (V/I) applied during an actuation. For a given intended force output, an electrical parameter value (flux, current, or other parameter) is read from a look up table (LUT). The LUT may store a present value of the inductance of the reluctance actuator. The feedback control may be a quasi-static control in which the LUT is updated after actuation based on the monitored V/I. The feedback control may be real-time, with a controller comparing an estimated electrical parameter value based on the measured V/I with the value from the LUT.

The invention relates to a method for preventive function control in an electromagnetic spring pressure brake for a simpler and more accurate determination of the critical operating state. The spring pressure brake comprises at least one coil, and an armature disk, a coil carrier having compression springs distributed thereon, a control module, and a monitoring module having at least one semiconductor component, a current measuring device, and a voltage measuring device, wherein the method comprises the following steps: Initially, the spring pressure brake is controlled by the control module by means of a voltage. Next, the state variables current (I) and voltage (U) at the electromagnetic spring pressure brake are measured by the monitoring module. Subsequently, a determination variable (T; F) of the electromagnetic spring pressure brake is determined by the monitoring module. Said determination variable (T; F) is summed over a range (a), which extends from the starting point of the actuation to a point (W), at which the armature disk begins to move. At the point (W), a current value is detected, at which the movement of the armature disk begins. The determination variable (T; F) is additionally summed over a range (b), which extends from the point of actuation, when the current (I) again reaches the value detected above, up to the point, at which a constant current is reached. Subsequently, a ratio (X) is calculated from the sum of the determination variable over the range (a) to the sum of the determination variable over the ranges (a) and (b). Upon reaching or exceeding a predetermined value (Y) by the value of the ratio (X), a state signal relating to the spring pressure brake is output.

A method for controlling a part movable with a coil. In this case, a current flowing through the coil and/or a voltage applied to the coil is/are scanned in order to generate a coil signal. In a further step, at least one movement parameter representing an oscillatory movement of the part is ascertained by using the coil signal. Finally, at least one signal parameter of a dither signal is optionally changed to generate the oscillatory movement by comparing the movement parameter to the at least one setpoint value to adapt the oscillatory movement to the setpoint value.

The invention relates to a device for controlling armature solenoid provided with a DC voltage source (14), at least one buffer capacitor (18), which is connected in parallel to the DC voltage source (14) and has a known capacitance (C), and a first switch (28), which is arranged between the DC voltage source (14) and the buffer capacitor (18). The exciter coil (16) and a second switch (30) arranged in series therewith are connected in parallel to the buffer capacitor (18). A control and evaluation unit (22), when the buffer capacitor (18) is charged, opens the first switch (28) and closes the second switch (30) in order to determine, on the basis of the measurement voltage (20), the frequency of the resonant circuit having the capacitance (C) of the buffer capacitor (18) and the inductance (L) of the armature solenoid (12). The inductance (L) of the armature solenoid (12) is determined on the basis of the frequency, and the air gap width (h) of the armature solenoid (12) is determined on the basis of the inductance. The PWM control signal with which the armature solenoid (12) is operable in order to generate a predefined force to be applied by the armature solenoid (12) is applied to the second switch (30) on the basis of a look-up table or a mathematical modelling of the electromagnetic behavior of the armature solenoid (12).

According to an embodiment of the present invention, there is provided a method of diagnosing an abnormal state of a valve including: applying a current having a predetermined intensity to a valve; estimating a resistance value of the valve on the basis of an intensity of a feedback current from the valve according to the application of the current and a voltage between both terminals of the valve; and when a difference between a resistance value of the valve estimated at a first time point and a resistance value of the valve estimated at a second time point is greater than or equal to a threshold, determining that abnormality has occurred in the valve.

A method for estimating a property of an electrical switching device includes: measuring the electric current flowing through the coil; measuring the supply electrical voltage of a control circuit for the actuator; injecting an electric current pulse into the coil; identifying a first time corresponding to the time for which the current flowing through the coil reaches a predetermined threshold value when the current increases following the injection of the pulse; identifying a second time corresponding to the time for which the current flowing through the coil again reaches the predetermined threshold value when the current decreases after the spike; and estimating the resistance of the coil on the basis of the ratio of the sum of the values of the voltage that are measured between the second time and the first time, to the sum of the values of the current that are measured between the second time and the first time.

A system may include an armature configured to move between a first position that electrically couples the armature to a first contact and a second position that electrically couples the armature to a second contact. The system may also include a coil configured receive a current, such that the current conducting in the coil is configured to magnetize a core. The magnetized core may cause the armature to move from the first position to the second position. The system may also include a control system configured to detect a position of the armature based on an inductance of the coil.