Abstract: It is presented a gate driver circuit for driving an electric switch, the switch being arranged to control a main current using a gate signal. The gate driver circuit comprises: a non-linear capacitor means having a lower capacitance when an applied voltage is under a threshold voltage and a higher capacitance when an applied voltage is over the threshold voltage, wherein the non-linear capacitor is arranged to be connected between a high voltage connection point of the switch and a connection point for the gate signal; a current change rate sensor, the current change rate sensor being configured to detect changes in a main current of the electric switch and to control a gate signal of the electric switch depending on the current change; a gate buffer; and at least one current source, arranged to drive the gate buffer. The current change rate sensor is connected to control the current source to thereby control the gate signal of the electric switch.

Abstract: It is presented a gate driver circuit for driving an electric switch, the switch being arranged to control a main current using a gate signal. The gate driver circuit comprises: a non-linear capacitor means having a lower capacitance when an applied voltage is under a threshold voltage and a higher capacitance when an applied voltage is over the threshold voltage, wherein the non-linear capacitor is arranged to be connected between a high voltage connection point of the switch and a connection point for the gate signal; a current change rate sensor, the current change rate sensor being configured to detect changes in a main current of the electric switch and to control a gate signal of the electric switch depending on the current change; a gate buffer; and at least one current source, arranged to drive the gate buffer. The current change rate sensor is connected to control the current source to thereby control the gate signal of the electric switch.

Abstract: The present invention relates to an electrical drive unit comprising a circuit board, a plurality of components, attached to a first side of the circuit board, a heat sink, arranged on the first side of the circuit board, a positioning assembly, arranged on a second side of the circuit board opposite the first side of the circuit board. The circuit board comprises a plurality of holes between the first and second sides, where through the positioning assembly has a plurality of protrusions arranged against the plurality of components, such that each component of the plurality of components individually is pressed against the heat sink by the positioning assembly.

Abstract: The invention relates to a method for manufacturing a permanent-magnet excited rotor for a high speed electric motor, according to which method a support sleeve (1) is mounted with a pre-tension around the rotor body (2), characterised in that the sleeve is expanded by a liquid that solidifies and is solid at the working temperatures of the rotor, said liquid is injected under pressure between the sleeve and the rotor body and held under pressure during solidification.

Abstract: An induction motor comprises a stator (10) and a rotor (20), which includes material essentially blocking magnetic flux at high frequencies. A difference in number of stator slots and rotor slots is chosen so that the inductance of a winding provided in a stator slot is different from the inductance of a winding provided in another stator slot. A sense means, such as stator winding or separate sense winding, is provided in at least one of the stator slots and the sense means is arranged to allow measuring of the inductance thereof. The sense means constitutes an integrated sensor, which is both inexpensive and reliable. A method of sensing the rotor position and/or speed of an induction motor is also described.

Abstract: This invention propose a way of controlling the flux density in a current transformer to keep the transformer core saturated between two consecutive measurements in a sampling measurement system. Saturation disables transformation of primary to secondary current, and thereby disables losses in the secondary circuit during this time. Both AC and DC currents are possible to measure. The use of saturation of the transformer core also permits the core to be designed physically very small. In order to get effective and accurate low power consuming measurements, both the magnetic fields originating from primary current flowing in the primary winding and external magnetic fields must be symmetrically physically spread in the transformer core. This greatly limits the possible physical arrangement of the primary winding.

Abstract: The invention relates to an electric motor, in particular for high speed operation, comprising a motor housing (4); inside the housing (4), a stator (2) having a core (8) and windings (9) toroidally wound on the core (8); and a rotor (1) inside the stator (2). The motor comprises an inductance controlling ring (3) in soft-magnetic material around the stator core (8), increasing for each phase the leakage inductance and forming for each phase an integrated filter inducatnce (L1, L2, L3) outside the core (8) of the stator (2) but still inside the motor housing (4).

Abstract: The invention relates to an electric motor, in particular for high speed operation, comprising a motor housing (4); inside the housing (4), a stator (2) having a core (8) and windings (9) toroidally wound on the core (8); and a rotor (1) inside the stator (2). The motor comprises an inductance controlling ring (3) in soft-magnetic material around the stator core (8), increasing for each phase the leakage inductance and forming for each phase an integrated filter inducatnce (L1, L2, L3) outside the core (8) of the stator (2) but still inside the motor housing (4).

Abstract: The invention relates to an electrical machine with a winding (5) comprising a wire (8) consisting of individually insulated conductors (9), these conductors being wires or strands, characterized in that the insulated conductors (9) extend in a zigzag pattern between the edges of the winding (5) said edges being in thermal conductive contact with a cooling medium.

Abstract: A rotor for a high speed permanent magnet motor comprises a central spindle (20), and a plurality of magnet discs (21) stacked on the spindle (20) and axially clamped by a clamping device (24-26, 28) on the spindle (20) to form an axially pre-tensioned disc packet core (16). Each magnet disc (21) has at least one electrically insulating layer, and a reinforcement disc (23) is provided between the magnet discs (21) and/or between at least one of the magnet discs (21) and the clamping device (24-26, 28). The reinforcement discs (23) are clamped such that a clamping force generated frictional engagement is obtained between the reinforcement discs (23) and the magnet discs (21) by which centrifugal forces are transferred from the magnet discs (21) to the reinforcement discs (23) during motor operation, thereby relieving the magnet discs (21) of tensile stress.

Abstract: The invention relates to a method for manufacturing a permanent-magnet excited rotor for a high speed electric motor, according to which method a support sleeve (1) is mounted with a pre-tension around the rotor body (2), characterised in that the sleeve is expanded by a liquid that solidifies and is solid at the working temperatures of the rotor, said liquid is injected under pressure between the sleeve and the rotor body and held under pressure during solidification.

Abstract: A method for restarting a three-phase synchronous permanent magnet motor in which the rotor is still rotating and in which the motor is connected to a drive unit having a DC-stage with voltage measuring means, a variable voltage and frequency output stage including power switching devices, and a means for determining the current in two of the output phases from the drive unit, wherein the motor with the output stage is momentarily short-circuited, the current magnitudes generated by the motor in the two output phases are measured during the short-circuiting moment, the phase angle generated by the motor during the short-circuiting moment is calculated, the rotor speed is determined, and the drive unit is synchronized with the rotor to enable restarting of the motor.