A system for controlling operation of a contactor is provided. The system stops outputting a control signal to open the contactor, and then measures a low side sense signal from a low side sense circuit electrically coupled to a low side end of a contactor coil, or a high side sense signal from a high side sense circuit that is electrically coupled to a high side end of the contactor coil, to determine whether the contactor has a closed operational position, and if not, the system stops outputting another control signal to open the contactor.

A method of testing a solenoid of a directional control valve in a subsea hydrocarbon production system, the solenoid having a coil and an armature for operating the valve and the coil being energized by a drive voltage across it, the method comprises removing or reducing the drive voltage and sensing current through the coil to produce an indication of movement of the armature.

A solenoid driver may be provided for a solenoid with a coil selectively energized by a power supply in a first polarity. An energy storage device may be charged by the power supply. A circuit may be configured to connect the energy storage device to the coil in a second polarity that is a reverse of the first polarity whenever the power supply is selectively turned off or unexpectedly interrupted.

A solenoid drive device includes a first solenoid drive circuit, a second solenoid drive circuit, a selection circuit, and circuitry. The circuitry controls the first switching element and the second switching element with a duty control in a control cycle according to acquired values of the first drive current and the second drive current so that a first on/off switching direction of the first switching element at a start timing of the control cycle is opposite to a second on/off switching direction of the second switching element at the start timing. The circuitry determines whether a failure in at least one of the selector, the first solenoid drive circuit, and the second solenoid drive circuit occurs based on a change in the selection detection signal in a period during which an on/off state of the first switching element is different form an on/off state of the second switching element.

A method for controlling a current flowing through a consumer comprises the following steps, which are periodically traversed: determining a dither current based on a dither signal and a definite point in time, wherein the dither signal is determined by a frequency, an amplitude and a signal form and actuating a flow control valve to produce the sum of a target current and the determined dither current by the consumer. Furthermore, the method comprises determining an indication to the current flowing through the consumer; compensating the indication by the factor of the dither current; and providing the indication, wherein the determination of the dither current and the determination of the indication are synchronized with each other in a predetermined way.

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.

The magnetic coil driving circuit of the magnetic contactor according to the present invention comprises a semiconductor switch configured to open or close a circuit for magnetizing or demagnetizing a magnetic coil; a pulse width modulation unit configured to output a pulse signal as a control signal for turning on or off the semiconductor switch; a control unit configured to output a control signal for changing a pulse width of the pulse signal to the pulse width modulation unit; and a temperature detection and protection unit configured to detect a temperature inside the magnetic contactor, output an output signal for turning off the semiconductor switch when the temperature exceeds an allowable temperature, and control the semiconductor switch by the pulse signal from the pulse width modulation unit when the temperature is within the allowable temperature.

A control apparatus for controlling a linear solenoid by controlling a driving current supplied to the linear solenoid through a feedback control. The feedback control is executed by a feedback control system having parameters that are determined in accordance with an ILQ design method. In a frequency characteristic of a gain of a transfer function representing a ratio of an output to a disturbance in the feedback control system, the gain is lower than 0 [dB] throughout all frequency ranges.

A solenoid system and method can include: providing an energizing voltage to a coil of a solenoid; providing an AC signal superimposed onto the energizing voltage; detecting current through the coil including an AC current amplitude induced by the AC signal and including a DC offset current amplitude; determining the AC current amplitude is a low AC current amplitude based on an armature within the solenoid being in a retracted position or determining the AC current amplitude is a high AC current amplitude based on the armature being in an extended position with the control logic, and where the AC current amplitude is determined utilizing the AC signal for synchronous demodulation; and determining a temperature fault based on the DC offset current amplitude falling below a DC offset current amplitude threshold.

A method for determining a switching state of a valve that is actuated by a coil, wherein the method includes: respectively ascertaining a current flowing through the coil and a voltage applied to the coil at several times which follow one another with a prespecified time interval, calculating an inductance variable of the coil based on the currents, the voltage and the time interval, and determining the switching state based on the inductance variable. Also disclosed is a solenoid valve assembly.