Abstract: In order to be appropriately usable as an electric device for vibrating a panel attached to a housing, an electronic device including a piezoelectric element; a housing having a first principle plane having the piezoelectric element fixed thereto and a second principle plane opposite to the first principle plane; and a lid member having a joint portion for removably joining to the second principle plane; causes the housing to generate sound transmitted by vibrating a part of a human body, such that the piezoelectric element is provided on a first side in a first direction parallel to the first principle plane, and a joint position of the joint portion is provided on a second side opposite to the first side in the first direction.

Abstract: The electronic device including a piezoelectric element, a vibration plate having the piezoelectric element fixed thereto for generating air conduction sound by vibrating the piezoelectric element and sound to be transmitted by vibrating a part of a human body, a housing having the vibration plate fixed thereto, and an operation key provided to the housing, makes vibration of the vibration plate not likely to be transmitted to the operation key.

Abstract: A synchronous electric motor includes rotor having a plurality of radially-oriented magnetic dipoles and a stator. Stator teeth group with a plurality of sets of stator teeth are arranged in the same position in terms of an electrical angle with another stator teeth group to provide rotational symmetry about an axis of the rotor. In each of the stator teeth groups a predetermined number of stator teeth are arranged at intervals different from intervals of the rotor magnetic dipoles. A main coil is wound about a predetermined number of stator teeth with a sub-coil further wound around one or more a teeth. Phase and magnitude of a resulting magnetic field is adjusted by the number of loops of the main coil and sub-coil. A given stator tooth can produce maximum torque despite any difference between an alignment of the stator tooth and an inter-polar interval of the stator.

Abstract: A motor drive apparatus receiving power from a power source and driving a motor with independent polyphase systems of excitation coils, comprises: a control circuit and power converters each corresponding to one system, each including an inverter circuit, an interrupter circuit, and a temperature detector, the inverter circuits being connected in series to the power source and, while not short-circuited, supplying power to the excitation coil, wherein the control circuit detects an operating state of the motor, short-circuits the inverter circuits and interrupts the interrupter circuits for a subset of power converters defined according to the operating state, such that a source voltage is supplied to non-short-circuited inverter circuits, and, when a power converter exceeds a predetermined temperature, the control circuit short-circuits the inverter circuit and interrupts the interrupter circuit thereof, and, in another power converter not exceeding the predetermined temperature, operates the inverter circui

Abstract: The present invention provides a synchronous motor drive system designed to realize reduced vibration and noise along with high output. The system includes: inverters 101, 102, and 103 for converting a direct current to a three-phase alternating current; a current application control unit 52 that controls operations of the three-phase inverters; and a synchronous motor 41 driven by three-phase alternating currents supplied from the three-phase inverters. The current application control unit 52 determines, for each three-phase inverter, a current phase angle and a current amount of a three-phase alternating current to output, and each inverter supplies a three-phase alternating current having the determined current phase angle and current amount to a different one of three-phase coil groups 200a to 200c.

Abstract: A semiconductor element 100 including an MISFET according to the present invention is characterized by having diode characteristics in a reverse direction through an epitaxial channel layer 50. The semiconductor element 100 includes a silicon carbide semiconductor substrate 10 of a first conductivity type, a semiconductor layer 20 of the first conductivity type, a body region 30 of a second conductivity type, a source region 40 of the first conductivity type, an epitaxial channel layer 50 in contact with the body region, a source electrode 45, a gate insulating film 60, a gate electrode 65 and a drain electrode 70. If the voltage applied to the gate electrode of the MISFET is smaller than a threshold voltage, the semiconductor element 100 functions as a diode in which current flows from the source electrode 45 to the drain electrode 70 through the epitaxial channel layer 50.

Abstract: Provided is a synchronous motor including a rotor having magnetic poles distributed circumferentially along a rotation direction of the rotor at equal intervals, and a stator having stator teeth arranged circumferentially along the rotation direction of the rotor, each tooth wound with a stator coil by concentrated winding. Every M consecutive stator teeth belong to one of stator teeth groups arranged at equal intervals. The M consecutive stator teeth in each stator teeth group are arranged at intervals different from the intervals of the magnetic poles of the rotor. The stator coils wound around the M consecutive stator teeth are connected to separate terminals. A motor driver supplies currents of different phases to the stator coils via the respective terminals.

Abstract: A power converter for effectively reducing switching noise is provided. The power converter comprises a capacitor 111; switching devices Q11a and Q11b connected to the capacitor 111 in parallel; and a controller 105 that controls each switching device individually to perform switching operations. Each of the switching devices Q11a and Q11b forms a closed circuit together with the capacitor 111. The controller 105 controls the switching devices Q11a and Q11b to perform switching operations of switching ON or OFF at different timings such that at least two closed circuits including the switching devices Q11a and Q11b mutually cancel ringing voltages occurring therein, each ringing voltage occurring due to the switching operations performed by a corresponding switching device and having a frequency defined by an inductance of a corresponding closed circuit and an output capacity of a switching device included in the corresponding closed circuit.

Abstract: A motor drive apparatus receiving power from a power source and driving a motor with independent polyphase systems of excitation coils, comprises: a control circuit and power converters each corresponding to one system, each including an inverter circuit, an interrupter circuit, and a temperature detector, the inverter circuits being connected in series to the power source and, while not short-circuited, supplying power to the excitation coil, wherein the control circuit detects an operating state of the motor, short-circuits the inverter circuits and interrupts the interrupter circuits for a subset of power converters defined according to the operating state, such that a source voltage is supplied to non-short-circuited inverter circuits, and, when a power converter exceeds a predetermined temperature, the control circuit short-circuits the inverter circuit and interrupts the interrupter circuit thereof, and, in another power converter not exceeding the predetermined temperature, operates the inverter circui

Abstract: In a power conversion circuit operating with high frequency, an off-voltage control circuit 101u of a lower-arm gate drive circuit 24u controls the output voltage of a gate drive power supply 103u to change the output voltage to a voltage lower than a predetermined off voltage during a time period from termination of turn-off operation of a lower arm 22u until start of turn-on operation of an upper arm 21u, and thereafter return the output voltage to the predetermined off voltage immediately after termination of the turn-on operation of the upper arm 21u. With this control, short-circuiting through the upper and lower arms occurring due to a high voltage change dv/dt can be avoided, and the life of a switching element constituting the power conversion circuit improves, increasing the reliability of the power conversion circuit.

Abstract: An inverter comprising: a circuit including arms connected in parallel, each of the arms including a first switch and a second switch connected in series; and a gate drive circuit configured to control, by pulse-width modulation using synchronous rectification, each of the first switch and the second switch to switch to an on-state or an off-state, wherein each of the first switch and the second switch includes: a channel region that is conductive in both a forward direction and a reverse direction in the on-state, and that is not conductive in the forward direction in the off-state; and a diode region that is combined as one with the channel region, and that is conductive only in the reverse direction, the diode region being unipolar, and the gate drive circuit synchronizes a timing at which the gate drive circuit outputs a signal for causing the first switch to switch to the on-state with a timing at which the gate drive circuit outputs a signal for causing the second switch to switch to the off-state, and

Abstract: A semiconductor element 100 including an MISFET according to the present invention is characterized by having diode characteristics in a reverse direction through an epitaxial channel layer 50. The semiconductor element 100 includes a semiconductor layer 20 of a first conductivity type, a body region 30 of a second conductivity type, source and drain regions 40 and 75 of the first conductivity type, an epitaxial channel layer 50 in contact with the body region, source and drain electrodes 45 and 70, a gate insulating film 60, and a gate electrode 65. If the voltage applied to the gate electrode of the MISFET is smaller than a threshold voltage, the semiconductor element 100 functions as a diode in which current flows from the source electrode 45 to the drain electrode 70 through the epitaxial channel layer 50. The absolute value of the turn-on voltage of this diode is smaller than that of the turn-on voltage of a body diode that is formed of the body region and the first silicon carbide semiconductor layer.

Abstract: A semiconductor element 100 including an MISFET according to the present invention is characterized by having diode characteristics in a reverse direction through an epitaxial channel layer 50. The semiconductor element 100 includes a semiconductor layer 20 of a first conductivity type, a body region 30 of a second conductivity type, source and drain regions 40 and 75 of the first conductivity type, an epitaxial channel layer 50 in contact with the body region, source and drain electrodes 45 and 70, a gate insulating film 60, and a gate electrode 65. If the voltage applied to the gate electrode of the MISFET is smaller than a threshold voltage, the semiconductor element 100 functions as a diode in which current flows from the source electrode 45 to the drain electrode 70 through the epitaxial channel layer 50. The absolute value of the turn-on voltage of this diode is smaller than that of the turn-on voltage of a body diode that is formed of the body region and the first silicon carbide semiconductor layer.

Abstract: A semiconductor element 100 including an MISFET according to the present invention is characterized by having diode characteristics in a reverse direction through an epitaxial channel layer 50. The semiconductor element 100 includes a silicon carbide semiconductor substrate 10 of a first conductivity type, a semiconductor layer 20 of the first conductivity type, a body region 30 of a second conductivity type, a source region 40 of the first conductivity type, an epitaxial channel layer 50 in contact with the body region, a source electrode 45, a gate insulating film 60, a gate electrode 65 and a drain electrode 70. If the voltage applied to the gate electrode of the MISFET is smaller than a threshold voltage, the semiconductor element 100 functions as a diode in which current flows from the source electrode 45 to the drain electrode 70 through the epitaxial channel layer 50.

Abstract: Enhancing torque while reducing torque rippling. A synchronous electric motor, comprising a rotor 2 and a stator 3, wherein a plurality of stator teeth 7 form stator teeth groups 8 with three stator teeth 7 lined up circumferentially forming one group; for the three stator teeth, a main coil is independently wound and sub-coil is further wound around at least one of the stator teeth; coils in one phase are constituted by, in series, the three main coils included in one of the stator teeth groups 8 and sub-coils included in other stator teeth groups, serially connected; and coils in another phase comprise the sub-coils included in one of the stator teeth groups 8 as well as three main coils included in other stator teeth groups.

Abstract: Provided is a small-sized load drive system which, even with three three-phase inverters, significantly reduces noise regardless of control duty ratio. The load drive system includes three-phase inverters 301 to 303, and first, second, and third control units 401 to 403. The inverters 301 to 303 are connected to loads 211 to 213, respectively. The first control unit 401 generates sawtooth wave voltage and controls the inverter 301 according to the sawtooth wave voltage. The second control unit 402 generates inverse sawtooth wave voltage and controls the inverter 302 according to the inverse sawtooth wave voltage. The third control unit 403 generates triangular wave voltage which has ramps respectively equal to the sawtooth/inverse sawtooth wave voltage and either has a same phase or is out of phase by half a period relative to the sawtooth/inverse sawtooth wave voltage, and also controls the inverter 303 according to the triangular wave voltage.

Abstract: A power conversion apparatus includes: a MOSFET (12) which includes a channel (12b) and a body diode (12a) connected in parallel, the channel (12b) becoming conductive according to a control signal (C1), so that a flow path of a regenerative current of an inductor (16) is formed, and the body diode (12a) having the regenerative current of the inductor (16) flow in a forward direction; a shunt resistor (2) and a voltage measuring unit (9) which measure an amount of a current (Imeas) flowing into the MOSFET (12); a threshold designating unit (7) which designates a threshold current amount (Ithresh); and a synchronous rectification prohibiting circuit (4) which prohibits supplying the control signal (C1) in the case where the amount of the current (Imeas) measured by the shunt resistor (2) and the voltage measuring unit (9) is greater than the threshold current amount (Ithresh) designated by the threshold designating unit (7).

Abstract: To aim to reduce ripple current flowing through a capacitor in a power converter apparatus including a converter, the capacitor and an inverter. A current sensor 6 is connected between a capacitor 5 and an inverter circuit 7 for detecting current Iinv flowing from the capacitor 5 to the inverter circuit 7. A frequency detecting subunit 11 performs fast Fourier transform on a waveform of the current Iinv to detect a frequency of a frequency component having the largest amplitude. Also, the frequency detecting subunit 12 detects a zero-cross point of the frequency component having the largest amplitude. Then a carrier signal control subunit 13 performs control such that a frequency and a rise time of a PWM carrier signal for driving the converter circuit 4 match the frequency and the zero-cross point that have been detected by the frequency detecting subunit 11 and the phase detecting subunit 12.

Abstract: Provided is a synchronous motor including a rotor having magnetic poles distributed circumferentially along a rotation direction of the rotor at equal intervals, and a stator having stator teeth arranged circumferentially along the rotation direction of the rotor, each tooth wound with a stator coil by concentrated winding. Every M consecutive stator teeth belong to one of stator teeth groups arranged at equal intervals. The M consecutive stator teeth in each stator teeth group are arranged at intervals different from the intervals of the magnetic poles of the rotor. The stator coils wound around the M consecutive stator teeth are connected to separate terminals. A motor driver supplies currents of different phases to the stator coils via the respective terminals.

Abstract: The present invention provides a synchronous motor drive system designed to realize reduced vibration and noise along with high output. The system includes: inverters 101, 102, and 103 for converting a direct current to a three-phase alternating current; a current application control unit 52 that controls operations of the three-phase inverters; and a synchronous motor 41 driven by three-phase alternating currents supplied from the three-phase inverters. The current application control unit 52 determines, for each three-phase inverter, a current phase angle and a current amount of a three-phase alternating current to output, and each inverter supplies a three-phase alternating current having the determined current phase angle and current amount to a different one of three-phase coil groups 200a to 200c.