Abstract: A piston type compressor wherein the position of the piston highest pressure point is indicated and the rotor of the motor at the optimal starting angle aligned prior to the actual compression operation by providing a pre-pulse to rotate the rotor of the motor at least one full rotation at a certain frequency, during rotation measuring the load torque by the frequency converter as well as indicating the maximum load torque point and at the end aligning the rotor of the motor at the optimal starting angle of about 180° from the maximum pressure angle, and at the beginning of the actual compression operation setting the rotor position opposite to the maximum torque angle by feeding direct current to the stator winding and starting the motor by supplying maximum motor current to the motor to give the maximum torque and acceleration.

Abstract: Method and arrangement for determining the remaining lifetime of a component of a power electronics appliance, such as a frequency converter, in which the lifetime data that is dependent on the ambient conditions and operation as specified by the manufacturer of the component is used, in which method at least one magnitude connected to ambient conditions, such as temperature, is determined, at least one loading magnitude of the component, such as speed of rotation, is determined and the calculation of the remaining lifetime is performed on the basis of at least one magnitude connected to ambient conditions, such as temperature, and of at least one loading magnitude of the component, such as speed of rotation, as well as of the lifetime data that is dependent on these ambient conditions and loading as specified by the manufacturer of the component.

Abstract: Method and apparatus to start a frequency converter equipped with a direct current intermediate circuit, particularly when a permanent magnet motor whose rotor is rotating at the start-up time is connected to it, wherein the frequency converter has a network bridge (10) and load bridge (11), and the load bridge has controllable power semiconductor switches of the upper and lower branch (V1-V6) and parallel connected zero diodes (D1-D6), and a direct current intermediate circuit between them, and the said frequency converter uses a current transducer placed in the direct current intermediate circuit, and the analogue current signal composed by it features samples of the measured output currents, and the diverter switches of the frequency converter's upper branch are controlled using the bootstrap method, wherein start-up is initiated by controlling the controllable power semiconductor switch of the lower branch of at least one output phase to a conductive state for one or several periods of time, preferably of

Abstract: Method and arrangement for connecting an AC electric motor (M1, M2, . . . MN) to an AC electricity network (L) in a system which comprises a frequency converter (FC), with which the motor is started, and contactors (S11, S12, S21, S22, SN1, SN2), in which method the supply source is changed by means of the contactors from the frequency converter to a direct network supply, in which method the frequency converter is stopped before changing the supply source, and in which method in connection with changing the supply source the control of the contactors is started before stopping the frequency converter.

Abstract: The shape of the rising and falling edges of AC output voltage pulses of a PWM frequency converter is controlled by reducing a speed of change, and a height, of the AC output voltage pulse. The PWM frequency converter rectifies the alternating voltage of a supply network into a DC voltage which is filtered. A load bridge having power semiconductor phase switches forms an AC output voltage from the DC voltage for controlling the load. An average speed of voltage change of AC output voltage pulses is set using a phase switch to control at least one power component to be conductive and non-conductive in turn for a period of at least about one microsecond to change a pulse edge of the AC output voltage pulses into at least one micropulse, the width of which is controlled to increase towards a final state of the phase switch.

Abstract: Method and apparatus for measuring an earth fault current in an output circuit of an inverter (INU) operating on the PWM principle and forming alternating-current voltage from direct-current voltage, the output currents (iU, iV and iW) of which inverter are measured, and which inverter comprises at least two phase switches implemented with power semiconductor components (V1-V6, D1-D6), which switches, controlled by a control unit, connect their own output phases to a positive (+) pole and to a negative (?) pole of a direct-current voltage source such that the phase switches are repeatedly both in different positions and also in the same positions, wherein the results of current measurement during two opposite switch position combinations are recorded in memory, and the earth fault current is calculated by forming a difference of the measurement results of said combinations.

Abstract: Thermistor monitoring arrangement of an alternating-current electric motor controlled by a power transformer, such as a frequency converter, for at least one thermistor monitoring the temperature of the motor, in which is a power transformer (200), in which is a power stage (203) and a control unit (204), controlling an alternating-current electric motor (201) provided with a thermistor (202), and into which power transformer, such as a frequency converter, an input circuit connected to a thermistor located in the motor is integrated, to which input circuit a safety circuit (a so-called Safe Stop circuit) that prevents unexpected starting or ensures safe stopping of the frequency converter is connected.

Abstract: A polyphase filtering choke arrangement of a power electronics appliance, more particularly of a frequency converter. which arrangement comprises two separate magnetic cores, around both of which a polyphase winding is arranged, particularly for filtering the harmonics of a network current and the common-mode noise currents, wherein both the magnetic cores (1, 2, 101a-101c, 102a-102c, 130a-130d, 140a-140d) are shaped to form a closed magnetic circuit, the magnetic cores (1 and 2, 101a-101c and 102a-102c, 130a-130d and 140a-140d) are arranged one on top of the other, the magnetic cores are connected to each other with connecting pieces (11-13, 11a-13b, 111-113, 121-124), and the winding directions of the windings of the magnetic cores are opposing with respect to each other, in which case the fluxes produced in the magnetic cores of each current are of opposing directions, in which case the flux produced by the difference-mode current circulates via the connecting pieces from one magnetic core to another.

Abstract: A converter includes a converter bridge (101) adapted to transfer electrical energy between the AC terminal (102) and the DC terminal (103) of the converter. The converter also includes electrical paths bypassing the converter bridge for conducting overvoltage transients occurring in the AC terminal around the converter bridge to the DC terminal. Each electrical path includes a unidirectionally conductive semiconductor component (104a, 104b, 104c), such as a diode, and a voltage-limiting component (105) for which the ratio of voltage change to current change is small when the voltage of the voltage-limiting component is greater than a predetermined threshold voltage. Because of the overvoltage protection thus achieved, AC chokes can be omitted from the AC terminal or at least they can be designed smaller, reducing the load-dependent voltage drop of the DC terminal.

Abstract: An enclosure arrangement, with protection against touch, of a power electronics appliance, more particularly of a frequency converter (31, 51) and its additional devices (12, 13), which solution contains an enclosed power electronics appliance and one or more enclosed additional devices installed in connection with it, which enclosed power electronics appliance and additional devices are modules, which can be fitted to be installed in combination one above the other such that the protection against touch of the appliance entity formed is as great as or higher than the protection against touch of the separate appliances.

Abstract: A method and a parallel connection arrangement for equalizing the output powers of power converter units (INU11, INU12), in which power converter units is a semiconductor switch bridge controlled with pulse width modulation, and in which is a control unit arrangement (CU1, CU2) for forming control pulses, with which the semiconductor switches are controlled. The control unit arrangement delays the falling edge of the control pulses of at least one semiconductor switch of at least one power converter unit.

Abstract: An arrangement and method for placing a frequency converter in a cabinet, wherein the frequency converter is fitted in an instrument cabinet having a frame and walls, wherein the frame (101) of the instrument cabinet is of modular construction, and wherein the frequency converter is integrated in the instrument cabinet to form one or more frequency converter modules, each of which comprises a frame part and electric components in such manner that the electric components of the frequency converter are ready installed in the instrument cabinet frame at least mainly before being brought to the site of utilization.

Abstract: Three-phase AC or two-phase DC choke arrangement of a frequency converter, in which is a magnetic core, in which are the phase-specific pillars of the AC choke arrangement or the branch-specific pillars of the DC choke arrangement (1a, 1b), around which are arranged the phase-specific windings of the AC choke arrangement or the branch-specific windings of the DC choke arrangement (Ldc1+, Ldc1?) to filter difference-mode currents, and in which an additional pillar (3) for damping common-mode currents is arranged in the magnetic core of the choke. The additional pillar (3) is arranged without the phase-specific or branch-specific windings fitted around it, in which case damping of the common-mode currents is achieved by means of the common-mode impedance formed by the windings arranged around the additional pillar and around the phase-specific or the branch-specific pillars.

Abstract: Method and apparatus to start a frequency converter equipped with a direct current intermediate circuit, particularly when a permanent magnet motor whose rotor is rotating at the start-up time is connected to it, wherein the frequency converter has a network bridge (10) and load bridge (11), and the load bridge has controllable power semiconductor switches of the upper and lower branch (V1-V6) and parallel connected zero diodes (D1-D6), and a direct current intermediate circuit between them, and the said frequency converter uses a current transducer placed in the direct current intermediate circuit, and the analogue current signal composed by it features samples of the measured output currents, and the diverter switches of the frequency converter's upper branch are controlled using the bootstrap method, wherein start-up is initiated by controlling the controllable power semiconductor switch of the lower branch of at least one output phase to a conductive state for one or several periods of time, preferably of

Abstract: A method and a corresponding appliance for measuring the output current of a frequency converter, the frequency converter including a network bridge that can be connected to an AC network, a controllable three-phase load bridge that can be connected to an AC load, and a DC intermediate circuit between them, the DC intermediate circuit including a filter capacitor that includes controllable semiconductor switches in each phase and that are controlled by pulse-width modulation, and in which the currents of the output phases are determined based on measured samples of the current of the filter capacitor of the DC intermediate circuit.

Abstract: Method for synchronizing inverter units (INU11, INU12) that are connected in parallel and supply a motor, and a parallel connection arrangement, in which motor is either one winding, which is supplied by inverter units connected in parallel, or a plurality of parallel windings, in which each winding is supplied by its own inverter unit, in which parallel connection one inverter unit functions as a master and the others as slaves, in which method a telecommunications bus is arranged between the units, and in which each inverter unit has its own modulation cycle counter, which are synchronized with each other on the basis of telecommunications messages, preferably serial telecommunications messages.

Abstract: A method and an apparatus for measuring the output currents of a frequency converter, preferably a vector-controlled frequency converter, which comprises a mains bridge (10) connectable to an alternating-current network and a load bridge (11) connectable to an alternating-current load and between these a direct-voltage intermediate circuit, by using current samples obtained from a current measuring sensor in the intermediate voltage circuit, wherein a sample is taken from the signal of the current measuring sensor substantially simultaneously with a point of change of the output voltage vector and upon the lapse of a predetermined delay after the point of change after the switching effects have settled.

Abstract: An arrangement and method for monitoring a frequency converter, the frequency converter being a voltage-controlled PWM frequency converter provided with a control unit and having an uncontrolled or a main-frequency controlled main bridge connectable to an alternating-current source (UL1, UL2, UL3), a direct-voltage intermediate circuit and a controlled load bridge for producing a variable-frequency multi-phase output voltage (UU, UV, UW), which direct-voltage intermediate circuit of the frequency converter is provided with a small-capacitance direct-voltage capacitor, the main bridge being connected to the load bridge directly without a large-capacitance direct-voltage capacitor functioning as an intermediate energy storage, and the arrangement includes a measuring unit for measuring the direct voltage of the intermediate voltage circuit.