366 results about "Ac frequency" patented technology

Featured are methods for regulating the AC frequency of the electrical power be supplied on an electrical distribution system or grid. Such a method includes electrically coupling an energy storage sub-system to the electrical distribution network, where the energy storage sub-system includes one or more flywheel energy storage systems. Also featured as devices, systems and apparatuses embodying such methodologies or for use in implementing such methodologies of the present invention.

The present invention relates to a method and system for evaluating the quality of encoded video data without gaining access to the source data or the compressed video bitstream. The system is configured to decode compressed video data using an MPEG decoder to produce decompressed video data. The decoded data is analyzed to determine whether the decompressed video data is intra-coded. If so, a discrete cosine transform (DCT) is performed to produce a set of DCT coefficients for at least one AC frequency band in the decompressed video data. At the same time, quantization matrix data of a frame of the decompressed video data as well as a quantizer scale for each block of the decompressed video data are extracted. Thereafter, the variance of the converted DCT coefficients is obtained, and then an average quantization error for each set of said DCT coefficients is determined based on the variance, the quantization matrix, and the quantizer scale. Lastly, a peak signal to noise ratio (PSNR) is calculated based on the resultant average quantization error.

A marine power distribution arrangement includes a turbine-driven AC generator which supplies AC power at a frequency of 240 Hz through a switchgear unit to a transformer and a first power converter by which the power is converted to a variable frequency, variable voltage AC output for ship propulsion and to a second power converter by which the AC power is converted to a fixed voltage, fixed AC frequency or DC power to supply the ship service loads. A battery backup power supply may be switched in an emergency. In another embodiment four turbine-driven AC generators and two emergency power supplies are provided to drive two propulsion shafts as well as to supply the ship service loads.

A method and apparatus are provided for plasma-based processing of a substrate based on a plasma source having at least two adjacent electrodes positioned with the long dimensions parallel to define a first gap minimum between the two electrodes of from 5 millimeters to 40 millimeters. A second gap minimum is defined between the two electrodes and the substrate. AC power is provided to the two electrodes through separate electrical circuits from a common supply with the phase difference therebetween. A first gas and a second are injected into the plasma-containing volume between the two electrodes are different positions relative to the substrate. A lower electrode with a lower electrode width that is less than the combined width of the two electrodes is powered from a separately controllable ac power supply at an ac frequency different from that supplied to the two electrodes.

A switching power device uses a non-capacitor flyback converter circuit not provided with a smoothing input capacitor having a large capacity. Therefore, a power harmonic can be suppressed and a rush current preventing element is not required. A fluctuation in an output current to be supplied to a load is fed back to the non-capacitor flyback converter circuit by a feedback circuit at a lower speed than an input AC frequency. Therefore, it is possible to improve a power factor by causing an input AC current to be proportional to an input AC voltage. A voltage control circuit controls an output voltage so as to have a constant voltage, and the output voltage is dropped in proportion to an output current when the output current exceeds a threshold. Therefore, it is possible to have the same output characteristic as a power device comprising a low frequency power transformer.

A peer-to-peer approach is used for the transfer of electrical power between devices (10,30). A communications link (24) is used for negotiation of the details of a desired power-supply transaction between a power-supplying device and a power-receiving device, including the electrical specification of the power to be transferred. When the transaction details are settled, a power supply link (23) is used for implementing the agreed transfer of power. The negotiated electrical specification can include one or more of: the voltage, the waveform (ac or dc), the ac frequency, the power factor, the maximum current, and the total power for the proposed transfer.

The invention relates to an electrical subsystem to power a vehicle refrigeration system. The electrical subsystem includes an AC drive electrically coupled to a high voltage DC bus. The AC drive provides “refrigeration compressor AC power” responsive to a cooling demand. The electrical subsystem also includes a “low voltage DC bus”. The low voltage DC bus powers a plurality of low voltage refrigeration components including refrigeration fans. A microcontroller sets the compressor AC voltage and the compressor AC frequency. A method of preventing vehicle refrigeration system compressor stall includes the step of limiting the electrical AC power to the compressor such that the AC voltage does not droop causing a compressor stall. Also, an electrical subsystem for powering a compressor in a vehicle refrigeration system includes “V/f” operating information for the compressor, and a microcontroller commands the AC voltage and the AC frequency to the compressor.

A clock or other display component has a user input to a controller configured to control a mechanical display unit, and it may also control a digital display unit. The controller controls the display unit(s) as a function of input from the user. User input can change the display in predefined increments, for example in the case of a clock in 5, 10, 15, 30 and 60 minute increments, or in other predefined increments greater than 1 minute. The user inputs can be on the back of the unit, leaving the front of unit freely visible. The clock, and also the separate mechanical and digital display units of the clock, can be synchronized using an AC frequency signal from an external power supply. Also, a system and method controls mechanical pointers, such as clock hands, in such a way that the exact positions of the pointers are known to the control electronics so that the pointers and digital displays show the same information.

The invention discloses an AC-DC hybrid micro grid bidirectional power converter virtual synchronization motor control method, and relates to the AC-DC hybrid micro grid virtual synchronization motorcontrol field; the bidirectional power converter is a three-phase voltage source type PWM converter formed by IGBT switch tubes; the AC side is connected to a AC bus via a LC filter and a line impedance Z ac; the DC side is connected to a DC bus via a DC capacitor Cdc and an line impedance Zdc; the energy bidirectional transmission can be realized respectively via a frequency control unit, a virtual excitation control unit and a bidirectional power transmission control unit; the AC frequency and DC voltage can be directly controlled so as to keep AC-DC subnet load balancing; throughput characteristics of various types of power supplies and loads of the AC-DC subnet can be fully utilized so as to provide inertia for the AC frequency and DC voltage, thus enabling the bidirectional power converter to present sagging characteristics under a stable state, and building a bidirectional power converter closed loop system small signal model so as to provide a key parameter design method.

A marine power distribution arrangement utilizes generators driven at standard or higher than normal speeds and/or having a number of poles to produce electric power at a standard 50/60 Hz frequency or substantially higher than the standard 50/60 Hz frequency, such as 400 Hz. Each generator is a multi-phase, multi-circuit generator supplying isolated outputs on a plurality of lines to a propulsion power converter having isolated inputs to provide variable frequency, variable voltage power to a ship propulsion motor and to a service power converter to provide ship service power at a standard AC frequency or DC and at standard voltage for a service load. With this arrangement, power conversion transformers can, for the most part, be eliminated, thereby reducing the size and weight of the distribution system.

A method, device and system for responsive load management using frequency regulation credits. The method includes using an AC frequency measuring device, measuring a current AC frequency on an AC power line; using a power consumption measuring device, measuring a current power consumption on the AC power line over a period of time equal to a sampling interval; calculating a power consumption moving average of a last N power current power consumptions measured, where N is a positive integer greater than 1; generating credits or debits based on the current power consumption, the current AC frequency and the power consumption moving average; adding the credits or debits to a frequency regulation credit; and for each next sampling interval repeating measuring the current AC frequency, measuring current power consumption, calculating the power consumption moving average, generating the credits or debits, and adding the credits or debits to the frequency regulation credit.

An electrical potential difference between a slider body and a hard disk of a hard disk drive is eliminated based on the flying-height spacing of the slider body between the slider body and the hard disk. A predetermined bias voltage is applied between the slider body and the hard disk that includes a DC component and an AC component and that is based on the detected flying-height spacing of the slider body. The flying-height spacing can be detected based a minimum slider-to-disk clearance change from a design flying height of the slider at a frequency of the AC component as the DC component of the predetermined bias voltage is varied. Alternatively, the flying-height spacing can be detected based on a minimum electrodynamic response of the slider to a first harmonic of the AC frequency of the AC component as the DC component is varied.

The present disclosure is concerned with a power supply system for railway traction applications including a multilevel AC/DC converter. The converter comprises a plurality of series-connected single-stage cycloconverters or direct AC frequency converters connected between an AC supply line and a traction transformer. The transformer is operable at a transformer nominal frequency below 3 kHz and above the AC line frequency. On the secondary side of the transformer, more than one parallel-connected secondary converter are provided and connected to a DC link. In case of failure of one of the secondary converters, the multilevel AC/DC converter may continue to operate with reduced power delivered by the remaining operating levels.

A method for recognizing defects on inner and outer walls by magnetic flux leakage detection based on AC/DC combined magnetization is used for determining whether a defect is present on inner or outer wall of a material to be detected, which belongs to nondestructive detection field. The method is characterized in that the method comprises three basic steps of: (1) subjecting the material to magnetic flux leakage detection by AC/DC combined magnetization; (2) subjecting the magnetic flux leakage signals detected by a sensor to spectral analysis to obtain the magnitude of the frequency component of an AC magnetic flux leakage signal of a defect portion; and (3) setting the threshold of an AC frequency component and comparing the AC frequency component of the magnetic flux leakage signal with the threshold to determine whether the defect is present on the inner wall or on the outer wall of the material. The invention can conveniently determine the defect position and simultaneously execute inner/outer wall recognition by one-step magnetic flux leakage detection, thus facilitating the development of defect quantization after magnetic flux leakage detection.

The invention relates to an aluminum foil corrosion process for an electrolytic capacitor. The process comprises the following steps: preliminary treatment, AC pre-corrosion, intermediate treatment, subsequent corrosion and post-treatment. The process is characterized in that: the subsequent corrosion adopts a process of alternating multilevel low frequency AC corrosion and chemical corrosion; the adopted AC frequency is less than or equal to 30 Hz; the chemical corrosion is adopted after each level of AC corrosion; and the number of levels is usually 2 to 4. The aluminum foil corroded by the process has a square structured pore shape, less surface dissolution, and a specific volume improved by more than or equal to 10 percent. The process improves the corrosion efficiency and the face extension rate.

High efficiency conversion of heat energy to electrical energy is achieved using a ring of metallic components and anodically sliced, reduced barriers, high purity n-type and p-type semiconductor wafers. Energy produced by heating one set of fins and cooling another set is extracted from a ring of bismuth telluride based n-type wafers and antimony telluride based p-type wafers using make-before-break control of MOSfet switch banks. Standard AC frequencies and DC output result from rectification of make-before-break high frequency switched very high currents in the ring and a DC to AC converter. Solar energy stored in porcelain fragments extends the time that solar energy can be used as the heat source for the thermoelectric generator device.

An illumination device includes one or more LED's and a power supply configured to convert energy from a commercial AC power source and drive said LED's. The power supply includes a rectifier circuit, a phase detection circuit receiving an output voltage from the rectifier circuit and a switching element. A circuit includes the one or more LED's, an inductive element and a diode, and is coupled on a first end to the rectifier circuit and coupled on a second end to ground through the switching element. A current sensor is positioned to detect a current flowing to the light-emitting diode. A control circuit is coupled to receive the detected current and the detected phase of the rectified output voltage, and further coupled to the switching element and configured to generate a PWM signal for driving the switching element at a frequency higher than a commercial AC frequency. The PWM signal has a pulse width determined in accordance with one or more of a feedback control based on a current detected by the current sensor and a feed-forward control based on a phase of the pulsating voltage detected by the phase detection circuit.