Abstract:
An enclosure, wherein the enclosure is at least partly formed of a layered material (3), the inner layer (1) of the layered material being formed of porous metal and the outer layer (2) of the layered material being formed of hygroscopic porous material.
Abstract:
An exemplary method for determining a flow rate of a pump, includes measuring and storing the flow rate (QMean) when the pump is in operation, storing rotational speed (nMean) and torque (TMean) of the pump during measurement of the flow rate (QMean), determining torque (TManufacturer) corresponding to the measured flow rate (QMean), calculating a bias value of the torque (TBias) by comparing the torque determined from the characteristic curve (TManufacturer) and the stored torque (TMean) of the pump, and determining an operating point of the pump based on the bias value of the torque (TBias).
Abstract:
An exemplary arrangement and method for a power semiconductor switch, where a first current between a first electrode and a second electrode can be controlled based on a control voltage between a third electrode and the first electrode. The arrangement includes an inductance connected in series with the power semiconductor switch, wherein a first end of the inductance is connected to the first electrode, first measuring source for generating a first measurement voltage based on the first end's voltage with respect to a reference potential, second measuring source for generating a second measurement voltage on the basis of the inductance's second end voltage with respect to the reference potential, a comparator for comparing the first measurement voltage with the second measurement voltage, and driver for generating the control voltage. The driver being configured to generate a first control voltage level and a second voltage level of the control voltage.
Abstract:
A method and device are disclosed for synchronizing an inverter with an alternating voltage source. The method includes measuring a current generated by the alternating voltage source and flowing through diodes of the inverter, determining a phase angle and angular velocity relating to the alternating voltage source from the measured current for enabling synchronization between the inverter and the alternating voltage source, and starting modulation of the inverter according to the obtained phase angle and angular velocity.
Abstract:
A method and arrangement for operating a pump system are disclosed, the pump system including a pump arranged to be rotated with an AC motor, an inverter, the output of which is electrically connected to the AC motor, and a photovoltaic panel system electrically connected to feed DC power to the inverter. The method can include setting a voltage limit, and determining continuously voltage obtained from the photovoltaic panel system. When the determined voltage of the photovoltaic panel system is below the set voltage limit, frequency of the inverter can be controlled such that the ratio between output voltage of the inverter and the output frequency is substantially constant. When the determined voltage of the photovoltaic panel system exceeds the voltage limit, the inverter frequency can be controlled for keeping voltage of the photovoltaic panel system substantially at the voltage limit.
Abstract:
A method of estimating a rotor angle of a synchronous reluctance motor, which includes a stator and a rotor. First, a stator flux and a stator current are determined. Two orthogonal stator flux components in a stator reference frame are calculated from the stator flux. Two orthogonal stator current components in the stator reference frame are calculated from the stator current. A rotor orientation vector is then calculated using a known rotor direct or quadrature axis inductance component, the stator flux components, and the stator current components. The rotor orientation is estimated on the basis of the rotor orientation vector.
Abstract:
A method and apparatus are disclosed for monitoring accumulation of dirt on an air filter of a ventilation system including the filter and a fan controlled by a frequency converter. An initial value for an operating parameter is determined. A present operating point is determined based on a characteristic curves, and the mechanical power and rotational speed of the fan. A present value for the operating parameter is determined based on the present operating point, and accumulation of dirt is determined on the air filter based on the initial and present values of the operating parameter.
Abstract:
A method is disclosed for controlling an IGBT component and a gate driver. An exemplary method includes producing, with two separate driver circuits, a gate voltage for controlling the IGBT component, the outputs of the driver circuits being connected to free ends of a series connection of resistive components. A location, such as a midpoint between the series connection, forms the gate voltage.