Abstract: A motor driving circuit includes a three-phase inverter circuit 8, including three upper-arm switching elements 56a to 56c for driving upper arms of different phases of a three-phase motor 3, and three lower-arm switching elements 56d to 56f for driving lower arms of different phases. At least one of the upper-arm switching elements 56a to 56c and the lower-arm switching elements 56d to 56f is a semiconductor element that performs a diode operation. The diode operation is an operation in which a voltage less than or equal to a threshold voltage of a gate electrode G is applied to the gate electrode G with reference to a potential of a first ohmic electrode S, thereby conducting a current flow from the first ohmic electrode S to a second ohmic electrode D and blocking a current flow from the second ohmic electrode D to the first ohmic electrode S.

Abstract: A power conversion circuit includes a bidirectional switch 2. The bidirectional switch 2 has a first gate terminal G1, a second gate terminal G2, a first ohmic terminal S1 and a second ohmic terminal S2. The bidirectional switch 2 has four operation states. In the first state, the bidirectional switch 2 operates as a diode having a cathode as the first ohmic terminal S1 and an anode as the second ohmic terminal S2. In a second state, the bidirectional switch 2 operates as a diode having an anode as the first ohmic terminal S1 and a cathode as the second ohmic terminal S2. In a third state, the bidirectional switch 2 is bidirectionally conductive with via a diode between the first and second ohmic terminals S1 and S2. In a fourth state, the bidirectional switch 2 cuts off a bidirectional current between the first and second ohmic terminals.

Abstract: In a cooling system used in cooling of a heater housing box, the present invention presents an apparatus for stabilizing power supply of heater housing box cooling apparatus capable of changing over a plurality of taps provided in the winding of a power transformer before the output voltage exceeds an allowable voltage range when turning on alternating-current power supply. For this purpose, first resistor 1 for elevating slowly the output voltage of the power transformer when turning on the alternating-current power supply is provided at the secondary side of the power transformer, direct-current voltage V1 rectified and smoothed from the output voltage is delayed by the charging time of a first capacitor, and an electronic controller for operating a tap changeover relay for automatically changing over the plurality of taps provided in the power transformer is started before the output voltage exceeds the allowable voltage range.

Abstract: A heat exchange cooler capable of eliminating continuous radiation of high-frequency noise waves and reducing the man hour for the installation work, and a power circuit driving device used for it are provided. A commercial power transformer (311), which transforms commercial AC power (307) supplied from a heat generating element storing box to a specified range of voltage, is provided. Moreover, first relay (210) and second relay (212) are used for automatically switching a plurality of taps disposed at the coil of commercial power transformer (311) which keeps a wide range of commercial AC voltage from 200V to 250V in nominal voltage within a specified range of output voltage.

Abstract: A heat exchange cooler capable of eliminating continuous radiation of high-frequency noise waves and reducing the man hour for the installation work, and a power circuit driving device used for it are provided. A commercial power transformer (311), which transforms commercial AC power (307) supplied from a heat generating element storing box to a specified range of voltage, is provided. Moreover, first relay (210) and second relay (212) are used for automatically switching a plurality of taps disposed at the coil of commercial power transformer (311) which keeps a wide range of commercial AC voltage from 200V to 250V in nominal voltage within a specified range of output voltage.

Abstract: A power conversion circuit includes a bidirectional switch 2. The bidirectional switch 2 has a first gate terminal G1, a second gate terminal G2, a first ohmic terminal S1 and a second ohmic terminal S2. The bidirectional switch 2 has four operation states. In the first state, the bidirectional switch 2 operates as a diode having a cathode as the first ohmic terminal S1 and an anode as the second ohmic terminal S2. In a second state, the bidirectional switch 2 operates as a diode having an anode as the first ohmic terminal S1 and a cathode as the second ohmic terminal S2. In a third state, the bidirectional switch 2 is bidirectionally conductive with via a diode between the first and second ohmic terminals S1 and S2. In a fourth state, the bidirectional switch 2 cuts off a bidirectional current between the first and second ohmic terminals.

Abstract: A motor driving circuit includes a three-phase inverter circuit 8, including three upper-arm switching elements 56a to 56c for driving upper arms of different phases of a three-phase motor 3, and three lower-arm switching elements 56d to 56f for driving lower arms of different phases. At least one of the upper-arm switching elements 56a to 56c and the lower-arm switching elements 56d to 56f is a semiconductor element that performs a diode operation. The diode operation is an operation in which a voltage less than or equal to a threshold voltage of a gate electrode G is applied to the gate electrode G with reference to a potential of a first ohmic electrode S, thereby conducting a current flow from the first ohmic electrode S to a second ohmic electrode D and blocking a current flow from the second ohmic electrode D to the first ohmic electrode S.

Abstract: In a cooling system used in cooling of a heater housing box, the present invention presents an apparatus for stabilizing power supply of heater housing box cooling apparatus capable of changing over a plurality of taps provided in the winding of a power transformer before the output voltage exceeds an allowable voltage range when turning on alternating-current power supply. For this purpose, first resistor 1 for elevating slowly the output voltage of the power transformer when turning on the alternating-current power supply is provided at the secondary side of the power transformer, direct-current voltage V1 rectified and smoothed from the output voltage is delayed by the charging time of a first capacitor, and an electronic controller for operating a tap changeover relay for automatically changing over the plurality of taps provided in the power transformer is started before the output voltage exceeds the allowable voltage range.

Abstract: A heat exchange cooler capable of eliminating continuous radiation of high-frequency noise waves and reducing the man hour for the installation work, and a power circuit driving device used for it are provided. A commercial power transformer (311), which transforms commercial AC power (307) supplied from a heat generating element storing box to a specified range of voltage, is provided. Moreover, first relay (210) and second relay (212) are used for automatically switching a plurality of taps disposed at the coil of commercial power transformer (311) which keeps a wide range of commercial AC voltage from 200V to 250V in nominal voltage within a specified range of output voltage.

Abstract: A duplex voice communication radio transmitter-receiver according to the present invention is provided with a low-pass filter arranged before a time compressing device in a transmitter section for cutting off a higher frequency portion of the band of a voice signal thus to decreasing the maximum modulation frequency of the same to less than a half so that it can be operated with the use of an assigned, single frequency transmission radio wave of which frequency band is legally limited, improved in the utilization of frequencies, minimized in the delay of communication signals, and enhanced in the articulation and intelligibility of a reproduced voice sound.

Abstract: A part of a tube, through which a fluid passes, is cooled by means of an electronic cooling element and a flow rate of the fluid is measured on the basis of a temperature of a surface of the tube cooled. Not only can the flow rate of the liquid flowing through the tube be determined in a noncontacting manner and a very small flow rate of the liquid be determined, but also the tube is cooled so that no bubbles are generated, and thus the measurement of the liquid, which is apt to generate gases, such as low boiling point liquid, is possible. In addition, the measurement is not influenced by the gases dissolved in the liquid and merely the temperature difference resulting from the flow of the fluid, that is, the rise of the temperature of the fluid, is detected to prevent the measurement from being influenced by the installing posture of the flow meter, so that a highly accurate measurement is possible. Consequently, stable and sure controlling flow rate of liquid is possible.

Abstract: A numerically controlled apparatus wherein a tool can be returned by a high speed retrograding operation without damaging a chip of a tool or a work. The numerically controlled apparatus comprises a command executing block which decodes a working program for each of block commands and controls controlling driving of a tool to work a work. A retrograde command storage block extracts data necessary for the production of a retrograde block command from the working program and stores the extracted data therein. Upon reception of a retrograding signal, an escapement command producing block produces an escapement block command, and a retrograde block command producing means produces a retrograde block command. Then, an escapement/retrograde command execution controlling block causes the command executing block to execute the escapement block command and the retrograde block command.

Abstract: A part of a tube, through which a fluid passes, is cooled by means of an electronic cooling element and a flow rate of the fluid is measured on the basis of a temperature of a surface of the tube cooled. Not only can the flow rate of the liquid flowing through the tube be determined in a noncontacting manner and a very small flow rate of the liquid be determined, but also the tube is cooled so that no bubbles are generated, and thus the measurment of the liquid, which is apt to generate gases, such as low boiling point liquid, is possible. In addition, the measurement is not influenced by the gases dissolved in the liquid and merely the temperature difference resulting from the flow of the fluid, that is, the rise of the temperature of the fluid, is detected to prevent the measurement from being influenced by the installing posture of the flow meter, so that a highly accurate measurement is possible. Consequently, stable and sure controlling flow rate of liquid is possible.