摘要:
A vector control system for an induction motor driven by a power converter which generates three phase ac currents containing harmonics. In the system, an exciting current command value and a torque current command value in a rotating magnetic field coordinate system are applied, induction motor primary currents in a stator coordinate system is detected at a period which is the same or integral multiple of that of the harmonic components by integration operation, the detected value of the integrated primary currents is subjected to definite integration over the same time interval as the period thereof thereby detecting fundamental wave components of the primary currents without the harmonic components, the fundamental wave components are transformed in the form of rotating magnetic field coordinate system thereby detecting an exciting current component and a torque current component, a deviation between the exciting current command value and the detected actual exciting current component and a deviation between the torque current command value and the detected actual torque current component are detected respectively, and producing and applying to the power converter three phase ac voltage command values in the stator coordinate system tending to reduce the deviations to zero.
摘要:
A parallel multi-inverter system including a plurality of inverters connected in parallel to each other through one or more parallel reactors, wherein output voltages of the inverters are controlled on the basis of the polarity of an output voltage command signal and a comparison result between a value obtained by converting the output voltage command signal into a positive one and a carrier signal to reduce harmonic components of the line-to-line voltages, and further two different switching modes to set the output voltage of the system zero are equally used to prevent a circulating current from flowing through the parallel reactors during each zero potential period of the output voltage of the system.
摘要:
A converter circuit includes three-phase unit converters connected in cascade in two stages for supplying electric power to a load. In a region in which the converter output voltage ratio is small, the firing phases of both converters are so set that a phase difference of 120.degree. makes appearance therebetween, while in a region in which the converter output voltage ratio is large, the firing phases are so set as to have a phase difference of 60.degree. therebetween, whereby an angular difference of 90.degree. to 30.degree. is caused to occur constantly between the phases of voltage ripple components of the unit converters. Power factor of a power supply source is improved while ripple in the output voltage of the converter circuit is reduced.
摘要:
A current-circulating cycloconverter includes a positive converter and a negative converter connected in anti-parallel with each other through a DC reactor. A load is connected to an intermediate tap of the DC reactor. When a load current flowing to the load is smaller than a predetermined value, a circulating current flowing through the positive and negative converters is held at a minimum required value. A circulating current is caused to additively flow for canceling a voltage drop produced across the DC reactor when the load current exceeds the predetermined value.
摘要:
In induction motor driven by a voltage-type inverter, the torque current component is determined by detecting a primary current flowing to the induction motor. On the basis of the torque current component determined, the output voltage and frequency of the voltage-type inverter are controlled. Additionally, the rotational speed of the induction motor is estimated on the basis of the detected torque current component and the speed of the induction motor is controlled such that the estimated speed signal coincides with a speed command signal.
摘要:
Disclosed herein is a method of manufacturing a semiconductor device. The method comprises forming a first silicon film on a semiconductor substrate, forming a second silicon film on the first silicon film, forming a third silicon film on the second silicon film, and forming a first diffusion barrier film on the third silicon film. The method further comprises performing a thermal treatment to diffuse an impurity included in the second silicon film into at least the first silicon film and the semiconductor substrate, respectively.
摘要:
A video output apparatus includes a video output unit which outputs a video signal while switching the format of the video signal between a first format and a second format for expressing color differently. The video output apparatus also includes a mute signal generation unit which generates, as a muting video signal, a specialized video signal expressing a color in which the difference between the color displayed when the specialized video signal is interpreted in its own format and the color displayed when the specialized video signal is interpreted in a different format is a minimum. The video output apparatus further includes a selection unit, which selects one of the video signal outputted by said video output unit and the mute signal generated by said mute signal generation unit and outputs the selected signal, and a control unit, which causes the selection unit to select the mute signal in a period including the switch performed by the video output unit.
摘要:
A video/audio encoding unit encodes an inputted video/audio signal in a format compliant with a predetermined technical standard. A differential signal output unit outputs the encoded data in the form of a differential signal defined by the predetermined technical standard. The differential signal output unit appends the data encoded by the video/audio encoding unit to a data transmission unallocated region of a communication line defined by the predetermined technical standard and then transmits the resulting data. Because the data transmission unallocated region, which is not directly used in normal data transmission, is thus effectively utilized in data transmission, a larger volume of information can be transmitted and received.
摘要:
An inter-record alteration detection code verification unit 36 calculates an inter-record alteration detection code by merging a record alteration detection code stored in a record to read from a database 34 and a record alteration detection code in the immediately previous record so as to generate a code and applying a predetermined hash operation to the generated code. The verification unit verifies whether the calculated inter-record alteration code coincides with the inter-record alteration detection code stored in the record to read. If they coincide with each other, data is determined to be not altered.
摘要:
A process for manufacturing a semiconductor device, comprising: preparing a substrate in which a silicon-containing resist pattern is formed on a processed-material layer, dry-etching the processed-material layer using the silicon-containing resist pattern as a mask to form a processed-material layer pattern, ashing the silicon-containing resist pattern to leave a silicon-containing residual resist, immersing the substrate on which the silicon-containing residual resist remains into pure water to swell and deform the silicon-containing residual resist, and immersing the substrate on which the swelled and deformed silicon-containing residual resist remains into diluted hydrofluoric acid to remove the silicon-containing residual resist.