Abstract: A power conversion device includes a power conversion circuitry configured to convert DC power into AC power by switching on/off a plurality of switching elements to switch each of a plurality of phase voltages to a voltage level selected from one of three levels including a first voltage, a second voltage higher than the first voltage, and a third voltage higher than the second voltage. A control circuitry is configured to control the plurality of switching elements so as to convert DC power into AC power without producing a combination of the first voltage and the third voltage between any two phases of the plurality of phase voltages.

Abstract: A power conversion device includes a power conversion circuitry configured to convert DC power into AC power by switching on/off a plurality of switching elements to switch each of a plurality of phase voltages to a voltage level selected from one of three levels including a first voltage, a second voltage higher than the first voltage, and a third voltage higher than the second voltage. A control circuitry is configured to control the plurality of switching elements so as to convert DC power into AC power without producing a combination of the first voltage and the third voltage between any two phases of the plurality of phase voltages.

Abstract: A matrix converter includes a power converter circuit connectable on one side thereof with an alternating-current supply via a high- frequency filter and connectable on another side thereof with an alternating-current motor; a snubber circuit connected with a one-side line for connecting the high-frequency filter and the power converter circuit; a discharge switch discharging a charge accumulated in the snubber circuit depending on a voltage of the snubber circuit; and a control circuit configured to execute controlling the power converter circuit on the basis of a carrier frequency in test such that a test voltage is applied to the alternating-current motor, changing the carrier frequency in test on the basis of an operation state of the discharge switch, and determining constants of the alternating-current motor on the basis of a response state of the alternating-current motor at the time when the test voltage is applied.

Abstract: A matrix converter includes a power converter circuit connectable on one side thereof with an alternating-current supply via a high-frequency filter and connectable on another side thereof with an alternating-current motor; a snubber circuit connected with a one-side line for connecting the high-frequency filter and the power converter circuit; a discharge switch discharging a charge accumulated in the snubber circuit depending on a voltage of the snubber circuit; and a control circuit configured to execute controlling the power converter circuit on the basis of a carrier frequency in test such that a test voltage is applied to the alternating-current motor, changing the carrier frequency in test on the basis of an operation state of the discharge switch, and determining constants of the alternating-current motor on the basis of a response state of the alternating-current motor at the time when the test voltage is applied.

Abstract: There is provided an inverter device capable of simplifying the circuit structure, lowering the cast, and downsizing of the device. The inverter device detects a switching change of an inverter by a pulse and is equipped with a pulse signal detector capable of detecting a motor residual voltage or a phase and a detector for detecting a residual voltage or a phase. The inverter device includes a voltage detector, a circuit for detecting a pulse signal based on a comparison between a phase voltage detection value per one phase output from the voltage detector and a first reference voltage value, a circuit for detecting a line residual voltage based on phase voltage detection values of two phases output from the voltage detector, and a circuit for detecting a line phase based on a comparison between the line residual voltage and a second reference voltage value.

Abstract: There is provided an inverter device capable of simplifying the circuit structure, lowering the cast, and downsizing of the device. The inverter device detects a switching change of an inverter by a pulse and is equipped with a pulse signal detector capable of detecting a motor residual voltage or a phase and a detector for detecting a residual voltage or a phase. The inverter device includes a voltage detector, a circuit for detecting a pulse signal based on a comparison between a phase voltage detection value per one phase output from the voltage detector and a first reference voltage value, a circuit for detecting a line residual voltage based on phase voltage detection values of two phases output from the voltage detector, and a circuit for detecting a line phase based on a comparison between the line residual voltage and a second reference voltage value.

Abstract: A process for the production of polyethylene having a wide molecular weight distribution and good molding and good physical properties. It is produced using a catalyst consisting of components (A) and (B). Component (A) is a solid product prepared by reacting (i) the reaction product of a compound containing titanium, magnesium and halogen, and (ii) at least one compound selected from the group consisting of tetraalkoxyzirconium, zirconium tetrahalide and tetraalkoxytitanium, with an organoaluminum halide compound of the general formula: AlR.sup.1.sub.n X.sup.1.sub.3-n wherein R.sup.1 is an alkyl group, X.sup.1 is a halogen atom, and 0<n<3 or a halogen-containing titanium compound of the general formula Ti(OR.sup.2).sub.m X.sup.2 4-m, wherein R.sup.2 is an alkyl group, X.sup.2 is a halogen atom, and 0.ltoreq.m<4. Component (B) is an organoaluminum compound.

Abstract: A suppository base composition comprising 5-80% by weight of polyethylene glycol, 5-80% by weight of triglyceride of fatty acid having 6-22 carbon atoms and 5-80% by weight of a specifically limited alkylene oxide derivative has a melting point of 30.degree.-60.degree. C., a compatibility with both of a polar drug component and a non-polar drug component, and can provide suppositories having excellent moldability and storage stability.

Abstract: A suppository base composition comprising 5-80% by weight of polyethylene glycol, 5-80% by weight of triglyceride of fatty acid having 6-22 carbon atoms and 5-80% by weight of a specifically limited alkylene oxide derivative has a melting point of 30.degree.-60.degree. C., a compatibility with both of a polar drug component and a non-polar drug component, and can provide suppositories having excellent moldability and storage stability.

Abstract: A process for the production of polyethylene characterized in that the polymerization is carried out in the presence of an alcohol and in the presence of a polymerization catalyst prepared from (A) a solid catalyst component containing at least titanium, magnesium, and chlorine; (B) trialkylaluminum of the formula R.sup.1.sub.3 Al wherein R.sup.1 is an alkyl or cycloalkyl group; and (C) a chlorine-containing aluminum compound of the formula R.sup.2.sub.n AlCl.sub.3-n wherein R.sup.2 is an alkyl or cycloalkyl group, and n is a real number of from 1 to 2.

Abstract: Wood fibrous materials which are impregnated with one or more compounds selected from a group consisting of polyoxyalkylene glycol monoacrylates and polyoxyalkylene glycol, monomethacrylates, followed by curing the impregnated impregnant, are splendid in the dimensional stability and become good in other properties thereof.