Abstract: In a three-phase induction motor, each of coils of three phases has a first coil unit and a second coil unit placed in 180-degree symmetry, each of the coil units has a first coil and a second coil, the first coil is formed by winding a winding once in an electrical angle range of 180 degrees during a two-pole operation, the second coil is formed by winding the winding twice in a range of a center third when the first coil is equally divided into three parts in a circumferential direction, in such a manner that a current flows in a direction opposite to a direction of current flowing in the first coil.

Abstract: A numeric value control unit outputs a connection diagnostic signal to a target position switching unit to place the three-phase motor in a position at an angle that causes no torque generation upon application of a diagnostic current to the three-phase motor, and thereafter, outputs a connection diagnostic signal to a current instruction switching unit to apply a diagnostic current. Then, in order to apply a diagnostic current to the other two phases, the three-phase motor is placed in a position at an angle that causes no torque generation upon second application of a diagnostic current, and a diagnostic current is thereafter applied. When a diagnostic current is applied twice and in the case where no defect in connection is detected in either application, it is determined that connection is normal. Meanwhile, in the case where connection is detected once or twice, it is determined that connection is defective.

Abstract: An inverter system includes a converter, an inverter, a first switch SW1 that connects between the converter and an AC power source, a capacitor that smooths a DC power in a DC bus, a resistor Rr connected from a positive voltage side of the DC bus to ground, a second switch SW2 that connects between the resistor Rr and ground, and a controller that controls drive of the inverter system. The controller is configured to: after charging the capacitor, while the first switch SW1 is in an OFF state, turn on the second switch SW2 and obtain a first across voltage ER1 of the resistor Rx; turn on an element, among semiconductor elements of the inverter, that is connected to the negative voltage side of the DC bus, and then obtain a second across voltage ER2 of the resistor Rx; and inspect insulation resistance of a motor based on the across voltages ER1, ER2.

Abstract: An inverter system includes a converter, an inverter, a first switch SW1 that connects between the converter and an AC power source, a capacitor that smooths a DC power in a DC bus, a resistor Rr connected from a positive voltage side of the DC bus to ground, a second switch SW2 that connects between the resistor Rr and ground, and a controller that controls drive of the inverter system. The controller is configured to: after charging the capacitor, while the first switch SW1 is in an OFF state, turn on the second switch SW2 and obtain a first across voltage ER1 of the resistor Rx; turn on an element, among semiconductor elements of the inverter, that is connected to the negative voltage side of the DC bus, and then obtain a second across voltage ER2 of the resistor Rx; and inspect insulation resistance of a motor based on the across voltages ER1, ER2.

Abstract: A numeric value control unit outputs a connection diagnostic signal to a target position switching unit to place the three-phase motor in a position at an angle that causes no torque generation upon application of a diagnostic current to the three-phase motor, and thereafter, outputs a connection diagnostic signal to a current instruction switching unit to apply a diagnostic current. Then, in order to apply a diagnostic current to the other two phases, the three-phase motor is placed in a position at an angle that causes no torque generation upon second application of a diagnostic current, and a diagnostic current is thereafter applied. When a diagnostic current is applied twice and in the case where no defect in connection is detected in either application, it is determined that connection is normal. Meanwhile, in the case where connection is detected once or twice, it is determined that connection is defective.

Abstract: In a controller of a machine tool having a converter that converts an AC power supply to DC and a plurality of inverters that drive a feed axis and a spindle, a power outage preparation mode is judged when an AC power supply voltage becomes lower than a predetermined value, and power outage is judged when the power outage preparation mode continues for a time period exceeding a predetermined time period or when a DC voltage which is output from the converter becomes lower than VAL1. During the power outage preparation mode, a threshold VAL2 of a low voltage alarm provided at each inverter is changed to a value lower than VAL1. In addition, when the power outage is judged, a stopping operation or a retracting operation of the feed axis is executed.

Abstract: In a controller of a machine tool having a converter that converts an AC power supply to DC and a plurality of inverters that drive a feed axis and a spindle, a power outage preparation mode is judged when an AC power supply voltage becomes lower than a predetermined value, and power outage is judged when the power outage preparation mode continues for a time period exceeding a predetermined time period or when a DC voltage which is output from the converter becomes lower than VAL1. During the power outage preparation mode, a threshold VAL2 of a low voltage alarm provided at each inverter is changed to a value lower than VAL1. In addition, when the power outage is judged, a stopping operation or a retracting operation of the feed axis is executed.

Abstract: A stator includes: a core formed by laminating magnetic steel sheets; and an excitation coil and a detection coil which are wound around teeth provided at the core. The core includes a peripheral section which is disposed to surround the rotor and a detection section which is disposed at the interior of the peripheral section and has the teeth. When the magnetic steel sheets are laminated, each of the magnetic steel sheets forming the core includes a portion which constitutes the peripheral section and a portion which constitutes the detection section. The detection section is substantially U-shaped, and both sides of the U-shape become a pair of teeth which form one phase. A base portion of the substantially U-shape of the detection section connects with the peripheral section, and gaps are provided between the peripheral section and a part of the base portion which is the root of the teeth.

Abstract: Coils are formed into a coil group for a single phase by serially connecting a plurality of coils so that the resulting magnetic flux distribution is a sine wave distribution. The coil group for a single phase is constituted by a plurality of coil sets, formed from two coils that are wound around two adjacent magnetic pole teeth, connected in series. Each coil set includes coils of the two magnetic pole teeth constituting that coil set wound in opposite directions to each other looking from the inside of the stator. An electrical wire extending from an end winding of each coil is turned back so as to run in a direction opposite to an electrical wire connection to a start winding of that coil, and is connected to either a start winding of the next coil or a connection terminal.

Abstract: A stator includes: a core formed by laminating magnetic steel sheets; and an excitation coil and a detection coil which are wound around teeth provided at the core. The core includes a peripheral section which is disposed to surround the rotor and a detection section which is disposed at the interior of the peripheral section and has the teeth. When the magnetic steel sheets are laminated, each of the magnetic steel sheets forming the core includes a portion which constitutes the peripheral section and a portion which constitutes the detection section. The detection section is substantially U-shaped, and both sides of the U-shape become a pair of teeth which form one phase. A base portion of the substantially U-shape of the detection section connects. with the peripheral section, and gaps are provided between the peripheral section and a part of the base portion which is the root of the teeth.

Abstract: Coils are formed into a coil group for a single phase by serially connecting a plurality of coils so that the resulting magnetic flux distribution is a sine wave distribution. The coil group for a single phase is constituted by a plurality of coil sets, formed from two coils that are wound around two adjacent magnetic pole teeth, connected in series. Each coil set includes coils of the two magnetic pole teeth constituting that coil set wound in opposite directions to each other looking from the inside of the stator. An electrical wire extending from an end winding of each coil is turned back so as to run in a direction opposite to an electrical wire connection to a start winding of that coil, and is connected to either a start winding of the next coil or a connection terminal.

Abstract: A linear motor having a more preferable braking function is realized with a low cost. A linear motor has a slider and a stator. A driving winding is wound around the slider. A plurality of permanent magnets forming magnetic poles which invert at a predetermined period are provided on a surface of the slider opposing the stator. Teeth are formed on the stator with a predetermined spacing therebetween. The stator extends to a region outside of an effective movable range, and a braking winding is wound around the teeth in the extended portion. When the slider moves into a region outside of the effective movable range, an induced voltage is generated in the braking winding and a current flows. A thrust in a direction opposite to the movement direction of the slider is generated by the current.

Abstract: A linear motor having a more preferable braking function is realized with a low cost. A linear motor has a slider and a stator. A driving winding is wound around the slider. A plurality of permanent magnets forming magnetic poles which invert at a predetermined period are provided on a surface of the slider opposing the stator. Teeth are formed on the stator with a predetermined spacing therebetween. The stator extends to a region outside of an effective movable range, and a braking winding is wound around the teeth in the extended portion. When the slider moves into a region outside of the effective movable range, an induced voltage is generated in the braking winding and a current flows. A thrust in a direction opposite to the movement direction of the slider is generated by the current.

Abstract: To form magnetic poles P on a rotor, a plurality of slits extending along a radial direction in a region close to the magnetic poles P and extending along a circumferential or chord direction in mid areas between the magnetic poles P are formed. The width b of circumferential slit segments extending along the circumferential or chord direction is narrower than the width a of radius slit segments extending along the radial direction. Permanent magnets are disposed in the narrowed segments of the slits to suppress leakage of magnetic flux. Thus, in a motor in which magnetic paths separated by the slits are formed on the rotor to provide regions having different magnetic reluctances in a circumferential direction of the rotor, a structure in which a through hole penetrated by an output shaft of the motor can have a large diameter is provided.

Abstract: A plurality of projections are provided abutted with an outer circumference of a columnar axis inserted to an inner circumference of a rotor. The projections are provided in the direction of a magnetic pole in the rotor. When the rotor is fixed to the columnar axis, the projection parts are fixed by “plunge-in” and the other rotor inner circumference parts have an uniform clearance to the columnar axis. The clearance is filled with an adhesive agent, thereby fixing the rotor to the columnar axis.

Abstract: A plurality of projections are provided abutted with an outer circumference of a columnar axis inserted to an inner circumference of a rotor. The projections are provided in the direction of a magnetic pole in the rotor. When the rotor is fixed to the columnar axis, the projection parts are fixed by “plunge-in” and the other rotor inner circumference parts have an uniform clearance to the columnar axis. The clearance is filled with an adhesive agent, thereby fixing the rotor to the columnar axis.

Abstract: An induction motor controlling device realizes precise and discretional revolutional speed vector control without requiring a speed detector using an algorithm which is suitable for a system including a microcomputer.A three-phase-to-two-phase converter detects a torque current inside a motor as a DC quantity based on instantaneous values of motor currents. A slip frequency is estimated using the torque current, and the slip estimation is used to obtain a motor's revolutional speed. An error in revolutional speed estimation is compensated by a compensation value which is obtained by amplifying an excitation current common phase voltage command.

Abstract: A control unit for an induction motor continuously provides a precise output torque without being adversely affected by a magnetic saturation of an iron core, or varying precision of sizes of components constituting the motor or varying temperature of the motor. When a torque command value T* is smaller than a predetermined value Trf, an excitation inductance M is corrected in accordance with a torque voltage command Gq.multidot..DELTA.i1q which is calculated on the basis of a torque current command i1q* and a torque current i1q. Further, a secondary resistance r2 is corrected on the basis of the torque voltage command G.multidot..DELTA.i1q. A slip frequency is calculated on the basis of the secondary resistance r2, a magnetic induction command .phi.*, and torque current command i1q*. An angular frequency command .omega. is calculated. The magnetic induction command .omega.

Abstract: The drive control apparatus for a linear actuator according to the present invention uses fine actuators, such as an electrostrictive element, so that it is possible to manufacture a linear actuator drive control apparatus obtaining big driving force in spite of a size considerably smaller than the conventional magnetic motor and linear motors utilized electromagnetic force. In addition, since the fine actuator and the driving base repeats their fixings and seperatings, it is possible to make the driven stroke range of the driving base wide. Since the fixing operation and the separating operation are carried out when the speeds of the fine actuator and of the driving base are almost the same, generation of the shock due to sudden speed change of the fine actuator and the driving base at the same of their fixing and separating is prevented, and it is possible to obtain smooth driving of the driving base.