Abstract: A push-pull generator provided for supply of a medical instrument includes at least one capacitive branch connected to ground, preferably in a switchable configuration, in parallel to at least one of its two transistors. Such a capacitive switchable branch can consist of a series connection of one capacitor and one switch. Thereby one of the two half waves of the output voltage of generator can be specifically influenced and the other one of the two half waves can be left largely uninfluenced. If switchable branches comprising capacitors are connected in parallel to both transistors, both half waves of the output voltage of the generator can be influenced independently from one another. This arrangement allows the specific influence of half oscillations of a push-pull generator that is apart therefrom symmetric, whereby the application spectrum for supply of medical instruments with treatment current is enlarged.

Abstract: A generator includes a number of impulse generators that are individually controlled by means of a control device in a timely flexible manner. The RF voltage required for supply of a surgical instrument is thus composed of individual impulses. The same applies for the current flowing at the electrode of the instrument. Due to omitting resonance effects in the impulse generators and omitting of energy storage in a system that is able to oscillate (system of second order), the user has an increased degree of control of the wave forms of the voltage supplied to the instrument and the current flowing to the instrument.

Abstract: The electrosurgical instrument (11) according to the invention comprises at least one electrode (15, 16) for electrically acting on biological tissue. The electrode is coupled with a radio frequency generator (20) that is arranged in direct proximity of electrode (15) and/or (16). The radio frequency generator oscillates in a self-controlled manner with a frequency between 100 kHz and 10 MHz and is preferably supplied by a constant or timely varying direct voltage. The instrument (11) is thus connected via a line supplying a low frequency voltage or direct voltage with a supplying source, e.g. an apparatus (19).

Abstract: A power generator (22) according to the invention is configured in a self-oscillating manner. It comprises two cascode circuits (31, 32), the outputs (A1, A2) of which are connected with a parallel resonant circuit (23) in order to excite it in push-pull manner. The input transistors (33, 35) of cascode circuits (31, 32) are cross-coupled, whereas the control electrodes of the output transistors (34, 36) are connected with non-varying potential. The power oscillator (22) is self-controlled such that the transistors (33-36) comprise lowest switching losses.

Abstract: An electronically commutated motor (ECM) often employs a Hall sensor for reliable operation. Even when a Hall sensor is omitted from a motor having a plurality of stator winding phases (24, 26) and a permanent-magnet rotor (22), one can reliably detect direction of rotation of the rotor by the steps of: (a) differentiating a voltage profile obtained by sampling either (1) induced voltage in a presently currentless phase winding or (2) voltage drop at a transistor, through which current is flowing to a presently energized phase winding, and (b) using such a differentiated signal (du—24?/dt, du—26?/dt) to control current flow in an associated phase winding. In this manner, one obtains reliable commutation, even if the motor is spatially separated from its commutation electronics.

Abstract: An electronically commutated motor (ECM) often employs a Hall sensor for reliable operation. Even when a Hall sensor is omitted from a motor having a plurality of stator winding phases (24, 26) and a permanent-magnet rotor (22), one can reliably detect direction of rotation of the rotor by the steps of: (a) differentiating a voltage profile obtained by sampling either (1) induced voltage in a presently currentless phase winding or (2) voltage drop at a transistor, through which current is flowing to a presently energized phase winding, and (b) using such a differentiated signal (du—24?/dt, du—26?/dt) to control current flow in an associated phase winding. In this manner, one obtains reliable commutation, even if the motor is spatially separated from its commutation electronics.

Abstract: An electronically commutated motor (ECM) often employs a Hall sensor for reliable operation. Even when a Hall sensor is omitted from a motor having a plurality of stator winding phases (24, 26) and a permanent-magnet rotor (22), one can reliably detect direction of rotation of the rotor by the steps of: (a) differentiating a voltage profile obtained by sampling either (1) induced voltage in a presently currentless phase winding or (2) voltage drop at a transistor, through which current is flowing to a presently energized phase winding, and (b) using such a differentiated signal (du—24?/dt, du—26?/dt) to control current flow in an associated phase winding. In this manner, one obtains reliable commutation, even if the motor is spatially separated from its commutation electronics.

Abstract: An electronically commutated motor (ECM) often employs a Hall sensor for reliable operation. Even when a Hall sensor is omitted from a motor having a plurality of stator winding phases (24, 26) and a permanent-magnet rotor (22), one can reliably detect direction of rotation of the rotor by the steps of: (a) differentiating a voltage profile obtained by sampling either (1) induced voltage in a presently currentless phase winding or (2) voltage drop at a transistor, through which current is flowing to a presently energized phase winding, and (b) using such a differentiated signal (du—24?/dt, du—26?/dt) to control current flow in an associated phase winding. In this manner, one obtains reliable commutation, even if the motor is spatially separated from its commutation electronics.

Abstract: An electronically commutated motor (ECM) often employs a Hall sensor for reliable operation. Even when a Hall sensor is omitted from a motor having a plurality of stator winding phases (24, 26) and a permanent-magnet rotor (22), one can reliably detect direction of rotation of the rotor by the steps of: (a) differentiating a voltage profile obtained by sampling either (1) induced voltage in a presently currentless phase winding or (2) voltage drop at a transistor, through which current is flowing to a presently energized phase winding, and (b) using such a differentiated signal (du—24?/dt, du—26?/dt) to control current flow in an associated phase winding. In this manner, one obtains reliable commutation, even if the motor is spatially separated from its commutation electronics.

Abstract: A control circuit (150) for controlling the current supplied to a winding strand (102) in an electric motor (143). The control circuit comprises at least one semiconductor switch (106) and a control unit (108) for controlling the semiconductor switch(es). Each semiconductor switch (106) is connected to a respective winding strand (102), in order to control the current in said winding strand. The control unit (108) comprises an output (110) for applying a control signal (CTRL) to the semiconductor switch (106), and is configured to set the output (110), at least upon switch-off of the semiconductor switch (106), to high impedance in order to prevent a voltage at the control unit output from influencing, during the switch-off operation, a signal input at the semiconductor switch (106). The improved control circuit increases motor efficiency and reduces commutation noise.

Abstract: The invention relates to an electronically commutated motor (10) and to a method of controlling an electronically commutated motor (10). In order to reduce commutation noise, it is proposed to influence the working range of the power-stage transistors (20, 22) with the aid of a component (48), in such a way that each transistors produces, during energization of each respective stator winding, a substantially constant current through the stator winding (12, 14). Preferably, each power-stage transistor operates within a pinch-off range.

Abstract: The invention relates to an electronically commutated motor (10) and to a method of controlling an electronically commutated motor (10). In order to reduce commutation noise, it is proposed to influence the working range of the power-stage transistors (20, 22) with the aid of a component (48), in such a way that each transistors produces, during energization of each respective stator winding, a substantially constant current through the stator winding (12, 14). Preferably, each power-stage transistor operates within a pinch-off range.

Abstract: A control circuit (150) for controlling the current supplied to a winding strand (102) in an electric motor (143). The control circuit comprises at least one semiconductor switch (106) and a control unit (108) for controlling the semiconductor switch(es). Each semiconductor switch (106) is connected to a respective winding strand (102), in order to control the current in said winding strand. The control unit (108) comprises an output (110) for applying a control signal (CTRL) to the semiconductor switch (106), and is configured to set the output (110), at least upon switch-off of the semiconductor switch (106), to high impedance in order to prevent a voltage at the control unit output from influencing, during the switch-off operation, a signal input at the semiconductor switch (106). The improved control circuit increases motor efficiency and reduces commutation noise.

Abstract: A method of controlling synchronous running of a plurality of electronically commutated motors (22, 24, 26), each of which includes a stator having a stator winding (40, 42, 44), a permanent-magnet rotor (28, 30, 32), and at least one arrangement (34, 36, 38), associated with the respective motor, for sensing its rotor position and for generating a rotor position signal (H1, H2, H3). Also provided is an energization arrangement (46), to which the stator windings (40, 42, 44) of the motors are connected. The method includes the steps of detecting occurrence of a predetermined state of the rotor position signals (H1, H2, H3) and, in response thereto, triggering simultaneously commutation of the currents in all the motors.

Abstract: A protective circuit, for reducing electrical disturbances or interference during operation of a DC motor, features a series transistor (62) arranged in a supply lead from a DC voltage source (12) to a DC motor; an auxiliary voltage source (52), associated with that series transistor, having a substantially constant auxiliary voltage which is configured to make the series transistor (62) fully conductive when a supply voltage furnished by the DC voltage source is substantially free of electrical interference; and an analyzer circuit (32, 34, 36) for analyzing the supply voltage, which analyzer circuit is configured, upon the occurrence of electrical interference in the supply voltage, to increase the resistance of the series transistor (62) correspondingly, in order to reduce the influence of that electrical interference on the operation of the DC motor.

Abstract: A method of controlling synchronous running of a plurality of electronically commutated motors (22, 24, 26), each of which includes a stator having a stator winding (40, 42, 44), a permanent-magnet rotor (28, 30, 32), and at least one arrangement (34, 36, 38), associated with the respective motor, for sensing its rotor position and for generating a rotor position signal (H1, H2, H3). Also provided is an energization arrangement (46), to which the stator windings (40, 42, 44) of the motors are connected. The method includes the steps of detecting occurrence of a predetermined state of the rotor position signals (H1, H2, H3) and, in response thereto, triggering simultaneously commutation of the currents in all the motors.

Abstract: A protective circuit, for reducing electrical disturbances or interference during operation of a DC motor, features a series transistor (62) arranged in a supply lead from a DC voltage source (12) to a DC motor; an auxiliary voltage source (52), associated with that series transistor, having a substantially constant auxiliary voltage which is configured to make the series transistor (62) fully conductive when a supply voltage furnished by the DC voltage source is substantially free of electrical interference; and an analyzer circuit (32, 34, 36) for analyzing the supply voltage, which analyzer circuit is configured, upon the occurrence of electrical interference in the supply voltage, to increase the resistance of the series transistor (62) correspondingly, in order to reduce the influence of that electrical interference on the operation of the DC motor.

Abstract: An electronically commutated motor (ECM) often employs a Hall sensor for reliable operation. Even when a Hall sensor is omitted from a motor having a plurality of stator winding phases (24, 26) and a permanent-magnet rotor (22), one can reliably detect direction of rotation of the rotor by the steps of: (a) differentiating a voltage profile obtained by sampling either (1) induced voltage in a presently currentless phase winding or (2) voltage drop at a transistor, through which current is flowing to a presently energized phase winding, and (b) using such a differentiated signal (du_24?/dt, du_26?/dt) to control current flow in an associated phase winding. In this manner, one obtains reliable commutation, even if the motor is spatially separated from its commutation electronics.

Abstract: An electronically commutated motor (ECM) often employs a Hall sensor for reliable operation. Even when a Hall sensor is omitted from a motor structure, one can assure reliable startup, in a preferred rotation direction, if the motor (20) is designed with an auxiliary reluctance torque (Trel) which, when the motor is running in the preferred rotation direction (DIR=1), has a driving branch (130) that is effective where a gap (136) exists in an electromagnetic torque (Tel) between two successive driving portions of that electromagnetic torque (Tel), and by using the steps of (a) upon starting, controlling application of electrical energy to the motor (20) in such a way that, in the event of a start in the wrong rotation direction, the motor cannot overcome the braking reluctance torque (130?) which is then effective; and (b) monitoring rotor movement to determine whether the rotor (22) is rotating in the desired rotation direction (DIR=1).

Abstract: The invention provides a radiofrequency surgical apparatus comprising a high frequency generator having at least one active electrode output and at least one neutral electrode output to which a part neutral electrode of a neutral electrode pair can be connected, with individual electrodes of the neutral electrode pair being connected to an auxiliary voltage with a significantly lower frequency than the high frequency. A monitoring circuit produces from the auxiliary voltage and the auxiliary current flowing between the part neutral electrodes an impedance signal representative for the impedance between the two part neutral electrodes and transmits a high frequency generator blocking signal and/or an alarm signal on exceeding a first fixed upper alarm limit and/or a lower second upper alarm limit for the impedance signal which can be matched to the actual value of the impedance signal. The adaptation of the second alarm limit is effected by pressing a SET key.