Abstract: The direct torque control (DTC) principle is used to control the torque of a wound ring rotor slip induction machine, also known as a doubly fed or cascade machine, by utilizing a solid state inverter on the rotor side. In addition, the DTC principle is used to control the power factor at the stator terminals of the doubly fed machine to a desired level and also to perform the task of synchronization of stator voltage to the grid voltage. An integrated controller is used to implement these three functions.

Abstract: Non-linear inductor(s) are used to reduce the percent total harmonic distortion of the harmonics in the line currents in the input side rectifier system of an ac drive system. Several constructions for the non-linear inductor(s) are described. The non-linear inductor(s) may be constructed from E and I laminations. The gap depends on the construction of the middle leg of the E laminations and may have a step with a constant spacing or a variable spacing which depends on the stacking of the laminations. Alternatively the non-linear inductor(s) may be constructed from a toriodal core that either has a step gap or a variable type gap.

Abstract: The invention relates to a method for forming a duct, to a duct, and to a duct component intended to form the duct, by means of which it is possible to form, for example, cooling systems for electronic components. In the method, in such a duct intended to conduct a flowing pressurized substance such as a cooling liquid, a heating liquid, or a gas, which has a base component formed from a stiff material and a duct component formed from a more flexible material than the base component, a sealing lip is formed, which protrudes towards the opposite wall of the duct component in such a way that the sealing lip runs round all the duct walls that are in contact with the stiff material, i.e. parallel to the longitudinal axis in elongated ducts, is formed.

Abstract: The direct torque control (DTC) principle is used to control the torque of a wound ring rotor slip induction machine, also known as a doubly fed or cascade machine, by utilizing a solid state inverter on the rotor side. In addition, the DTC principle is used to control the power factor at the stator terminals of the doubly fed machine to a desired level and also to perform the task of synchronization of stator voltage to the grid voltage. An integrated controller is used to implement these three functions.

Abstract: The direct torque control (DTC) principle is used to control the torque of a wound ring rotor slip induction machine, also known as a doubly fed or cascade machine, by utilizing a solid state inverter on the rotor side. In addition, the DTC principle is used to control the power factor at the stator terminals of the doubly fed machine to a desired level and also to perform the task of synchronization of stator voltage to the grid voltage. An integrated controller is used to implement these three functions.

Abstract: The object of the invention is a sampling apparatus in a continuous industrial process for taking a sample of the substance to be monitored. The sampling apparatus is located on the wall of the pulp tank and it includes a sample chamber, which is equipped with a cover, and a filter. The sample chamber includes a closing device, by means of which the connection from the pulp tank to the sample chamber can be closed, as a result of which the filter remains in the sample chamber in the space between the cover and the closing device. The filter can be pulled out of the sample chamber for cleaning after the cover of the sample chamber has been opened. Another object of the invention is a sampling method and a cleaning method for the sampling apparatus presented.

Abstract: An inverter arrangement which comprises two inverter units which comprise an intermediate voltage circuit and phase-specific switch components. The inverter arrangement also comprises phase-specific one-phase autotransformers, the first poles of which are connected to the phase-specific outputs of the first inverter unit and the second poles to the phase-specific outputs of the second inverter unit, and thus the output voltage of the inverter is obtained from the third poles of the autotransformers.

Abstract: The invention relates to a method of correcting the flux midpoint in flux-controlled alternating current systems, the method comprising the steps of determining a stator flux estimate (&psgr;s,est) and determining the magnitude of stator current (is).

Abstract: A method and arrangement for adaptively compensating for load changes, particularly in connection with an electric motor drive which comprises a motor, the shaft of the motor being connected to a load (3) having a known moment of inertia; a device (2), such as an inverter, to control the motor, a torque controller being arranged in connection with the device; and a speed controller (1) arranged to control the speed of the motor. The method comprises steps of determining, during the load change, an estimate (Mh) for an external torque disturbance which causes load changes, and employing the torque disturbance estimate (Mh) determined during the previous load change for compensating for the external torque disturbance in controlling the torque of the motor.

Abstract: A method for controlling an inverter which comprises the switching components to be controlled, the method comprising the steps of determining a current vector ({overscore (i)}olo) for the inverter output; determining a flux vector ({overscore (&psgr;)}) for the inverter load; determining an angular speed (&ohgr;) for the inverter load; determining a resistance (R) for the inverter load.

Abstract: A method for manufacturing cooling elements for power electronic components and other cooling devices for electronic appliances, wherein molten metal is fed into a closed mould including a core part and a mould part. The metal is allowed to become solid whereafter the finished casting is removed from the mould. An insert package is assembled of lamellas made from a material which at least essentially corresponds to the casting material by pressing together several lamellas arranged next to one another such that an air slot remains between the lamellas arrranged next to one another such that an air slot remains between the lamellas. This insert package is machined such that it fits into a recess in the core part and the insert and the insert package is placed in the recess in the core part before closing the mould, whereby the package is fastened to the casting once the mould has been filled.

Abstract: The object of the invention is a sampling apparatus in a continuous industrial process for taking a sample (16) of the substance to be monitored (11). The sampling apparatus is located on the wall (11) of the pulp tank and it includes a sample chamber (14), which is equipped with a cover (13), and a filter (15). The sample chamber includes a closing device (18, 24), by means of which the connection from the pulp tank to the sample chamber can be closed, as a result of which the filter remains in the sample chamber in the space between the cover and the closing device. The filter can be pulled out of the sample chamber for cleaning after the cover of the sample chamber has been opened. Another object of the invention is a sampling method and a cleaning method for the sampling apparatus presented.

Abstract: A galvanic isolation coupling of a current loop comprising an operational amplifier (A1) as a part of the current loop and an optoisolator (1) comprising two receivers.

Abstract: A method and arrangement for determining state information of a high-power semi-conductor, the power semiconductor comprising a collector (C), an emitter (E) and a gate (G), and a gate driver (3) comprising an auxiliary voltage input is connected to the gate of the power semiconductor. The method is characterized by steps wherein the auxiliary voltage (Vcc) of the gate driver (3) is used as reference voltage, saturation voltage (Vsat) of the power semiconductor (1) is compared with the reference voltage by using an optoisolator (4), and a detection signal of state information is generated depending on the magnitudes of the saturation voltage and the reference voltage.

Abstract: A stabilized gate driver which comprises a current source transformer (T) which comprises a primary and a secondary coil, and a gate driver unit (GD) which includes a positive auxiliary voltage input (Va+) and a negative auxiliary voltage input (Va−).

Abstract: A method of defining an instantaneous value of a current (i2e) of a pulse-controlled inductive load when the impedance of the load is known, the method comprising the steps of: measuring the output voltage (u1) of a pulsed voltage source, and measuring the output current (i1) of the pulsed voltage source. The method is characterized by further comprising the steps of: low-pass filtering the measured output current (i1) of the pulsed voltage source to produce a fundamental wave current (i1lp), defining a load current estimate (i2est) by computation on the basis of the measured output voltage (u1) of the pulsed voltage source and the impedance of the load, high-pass filtering the load current estimate (i2est), and defining the instantaneous value of the load current (i2e) by adding the high-pass-filtered load current estimate (i2hp) to the fundamental wave current (i1p).

Abstract: A control circuit for controlling a semiconductor component (2) comprising an emitter (E), a collector (C) and a gate (G), the control circuit comprising a gate driver (GD) the output of which is connected to the gate (G) of the semiconductor component to be controlled. The control circuit further comprises a resistance coupling (1) where two series connections of a diode (V1, V2) and a resistor (R1, R2) are in an antiparallel connection and connected between the emitter (E) of the semiconductor component (2) and the zero potential (Com) of the gate driver (GD), and a feedback capacitor (C1) connected between the collector (C) of the semiconductor component (2) and the end of the resistance coupling (1) connected to the zero potential (Com) of the gate driver.

Abstract: An electrical system for use in isolation, the electrical system comprising a main engine (14), such as a gas turbine or a diesel engine, a generator (13) driven by the main engine (14) for generating a first alternating voltage (19), a first rectifier unit (12) for converting the first alternating voltage (19) generated by the generator (13) into a direct voltage on a DC bus (18), and at least one inverter unit (10, 15) for converting the direct voltage of the DC bus (18) into a second alternating voltage (20). The generator (13) driven by the main engine (14) for generating the first alternating voltage (19) is an asynchronous machine coupled directly to the shaft of the main engine (14), and the first rectifier unit (12) also comprises an inverter part for converting the direct voltage of the DC bus (18) into an alternating voltage with an adjustable frequency to said asynchronous machine (13) so as to use the machine as a motor.

Abstract: A control circuit for controlling a power semiconductor, the control circuit comprising a gate driver comprising a control input, auxiliary voltage inputs and an output. The control circuit further comprises a first semiconductor switch comprising a control electrode and main electrodes, a first main electrode forming a positive input pole of the control circuit and a second forming an output of the control circuit; a second semiconductor switch comprising a control electrode and main electrodes, a first main electrode forming a negative input pole of the control circuit and a second being connected to the output of the control circuit; a first resistance, a second resistance, a first zener diode whose anode is connected to the output of the gate driver and whose cathode to the positive input pole of the control circuit; and a second zener diode whose cathode is connected to the output of the gate driver and whose anode to the negative input pole of the control circuit.

Abstract: An inverter has a direct voltage intermediate circuit having a positive (Udc+) and a negative (Udc-) voltage busbar, and an auxiliary voltage source (1) which generates auxiliary voltages (U1, U2, U3) referenced to the positive (Udc+) and the negative (Udc-) voltage busbar of the direct voltage intermediate circuit. The inverter also has for each phase an upper (2) and a lower (3) power semiconductor, connected in series between the positive and the negative voltage busbar. The point between the semiconductors forms the phase output (Uout) of the inverter. An upper (4) and lower (5) gate driver outputs (8,9) are connected to the control electrode (G) of the respective upper (2) and lower (3) power semiconductors which have a positive (6) and a negative (7) auxiliary voltage input and a zero potential point (Com) connected to the output electrode (E) of the power semiconductor to be controlled.