66results about How to "Constant frequency" patented technology

The invention belongs to the field of wind generator power conversion device control, and relates to a constant-frequency direct power control method for a PWM converter under the condition of power grid voltage imbalance. The method comprises the following steps of: determining a sampling frequency; acquiring a three-phase power grid voltage, a three-phase power grid current and a direct-current side voltage, and calculating resultant vectors E and I of the power grid voltage and the power grid current in a three-phase static coordinate system respectively; calculating positive and negative sequence components of the power grid voltage and the power grid current; calculating an instantaneous power and an instantaneous power error; calculating a converter reference voltage, and performing inverse transformation on the converter reference voltage; performing amplitude limit on the converter reference voltage to obtain the resultant vector of the converter reference voltage after the amplitude limit; and modulating the resultant vector of the converter reference voltage after a space vector modulation algorithm is adopted for amplitude limit, and outputting the converter voltage. The method can inhibit the active power fluctuation of the system more effectively and greatly reduce the harmonic wave of the alternating-current side current; and the output converter voltage switch frequency is constant, so the output filter parameter design is simpler.

Fractional bit rate encoding in a discrete multi-tone (DMT) communication environment allows the transmission of fractional bit rates, thus maximizing the use of signal-to-noise ratio (SNR) available on each of the DMT carriers, or tones, while maintaining a constant power density over the entire frequency spectrum.

A switched mode power supply device comprising a power transistor periodically set to conduction and supplying a regulated voltage that comprises a ramp generation circuit controlled by a clock signal and periodically generating a ramp voltage. The device includes an amplifier error circuit between a reference voltage and said regulated output voltage and generates an error signal, and a comparator comparing the ramp voltage with said error voltage and providing an output signal for controlling said power circuit. The circuit is characterized in that it comprises a delay element delaying the setting to conduction of the power transistor so as to desynchronize the starting of the ramp and said setting to conduction.

The invention discloses an RC relaxation oscillator of a comparator offset, and is used for solving the technical problems that the stabilities of the frequency and the duty ratio of the prior RC relaxation oscillator are bad. The RC relaxation oscillator provided by the technical scheme comprises a reference voltage generating circuit, a capacitor charging-discharging circuit, a comparator and an inverter chain. A charge pump is used to generating two periodic triangular wave signals, the phase difference of which is 180 degrees; and, the comparator compares two triangular wave signals to generate a clock signal. Since the peak-to-peak value of the triangular wave signals is determined by a fixed reference voltage and is irrelevant to the offset voltage of the comparator, the charging or discharging time of the capacitor remains unchanged at each working state, so that the frequency of the oscillator is not changed. Due to the comparator offset, the frequency and the duty ratio of the oscillator are not affected by the offset voltage of the comparator; and, the stabilities of the frequency and the duty ratio are good. And moreover, only one comparator is used, so that the amount of the comparators is reduced by half.

The invention relates to a wind power generating technology and discloses a speed-self-regulating synchronous generating system. The speed-self-regulating synchronous generating system is characterized by comprising a shell and an exciter which is coaxially connected with the left side of the shell, wherein an electromagnetic torque coupler and a synchronous generator sleeved on the outer side of the electromagnetic torque coupler are arranged inside the shell; the electromagnetic torque coupler comprises an inner rotor shaft and an outer rotor shaft; an inner rotor is connected onto the inner rotor shaft; an outer rotor is connected onto the inner side of the outer rotor shaft; the synchronous generator comprises a generator rotor and a generator stator; the generator rotor is fixed on the outer side of the outer rotor shaft; and the generator stator is fixed inside the shell. The rotor of the synchronous generator is integrated with the outer rotor of the variable-frequency speed-regulating electromagnetic torque coupler, so that the rotation speed of the rotor of the synchronous generator is a synchronous rotation speed; and the exciting current is changed by regulating input of the synchronous generator exciter so as to ensure that the output voltage and the frequency of the generator are constant.

A handheld power tool, including a tool socket on a drive shaft for purposes of holding a tool, the drive shaft executing a rotating and partially tangentially striking movement using a tangential striking mechanism drivable by a drive. The tangential striking mechanism has an anvil associated with the drive shaft and a hammer associated with the drive, movable with respect to each other so as to strike each other axially when under the effect of the force of at least one first spring, and to strike each other tangentially when the anvil and the hammer are rotated. The hammer has a main mass, and an extra mass that is under the effect of a second spring couplable to the main mass.

Triangular wave oscillation circuits generate A-wave and B-wave with phases opposite to each other, and are capable of independently controlling oscillation levels of the A-wave and the B-wave. A slope switching circuit including an output voltage monitoring circuit, a slope switching control circuit, and an inverter, monitors output voltages of the triangular wave oscillation circuits, to switch an output voltage generation mode of one triangular wave oscillation circuit whose triangular wave reaches a high level, from an up-slope waveform mode to a down-slope waveform mode, and to switch an output voltage generation mode of the other triangular wave oscillation circuit, from the down-slope waveform mode to the up-slope waveform mode. An oscillation level control circuit controls an oscillation level of the other triangular wave oscillation circuit so that the output voltage of the other of the triangular wave oscillation circuit becomes a reference lower limit crest value during the switching.

The invention discloses a micromechanical gyroscope drive method, which comprises four steps of generating an AC (alternating current) signal, generating a static drive signal, detecting the signals and extracting amplitude and phase. Through the active accommodation to the disturbance inside a micromechanical gyroscope, the micromechanical gyroscope drive method can ensure that the frequency and the amplitude of a drive mode detection signal are kept constant and a phase difference between the drive mode detection signal and the AC drive signal is also kept constant. According to the invention, due to no need of tracking a resonant frequency of a drive mode, the influence to a micromechanical gyroscope system by modules such as a filter relevant to the frequency in the micromechanical gyroscope system is avoided, and the stability of the micromechanical gyroscope system can be enhanced.

A clock generator that outputs multiphase clocks comprises a ring oscillator that includes a plurality of inverter circuits connected in a circular pattern and outputs, from the inverter circuits, clocks provided with a delay time based on a delay control signal, a first frequency divider that divides an injection clock by a first value and outputs the clock as a reference clock, a second frequency divider that divides one of the multiphase clocks by a second value and outputs the clock as a comparison clock, and a frequency comparator that compares frequencies of the reference clock and the comparison clock and output the delay control signal based on a result of the comparison. The ring oscillator is configured to adjust the delay time based on the delay control signal.

The invention relates to the technical field of wind-driven power generator sets, and particularly discloses a hydraulic transmission system for transmitting the power generated by a wind wheel of a wind-driven power generator set to a power generator, wherein the hydraulic transmission system comprises a first hydraulic pump and a hydraulic motor; the power input end of the first hydraulic pump is connected with a wind wheel main shaft; the oil inlet of the first hydraulic pump is communicated with an oil tank, and the oil outlet of the first hydraulic pump is communicated with the oil inlet of the hydraulic motor; the oil outlet of the hydraulic motor is communicated with the oil tank; the power output end of the hydraulic motor is communicated with the power input end of the power generator; and an oil channel between the first hydraulic pump and the hydraulic motor is provided with a speed regulating valve. No matter how the wind speed changes, the transmission system can always enable the power generator to operate always at a constant speed, and can enable the power and frequency of electricity to be constant. The invention also discloses a wind-driven power generator set.

The invention discloses a magnetic field modulation principle-based double-rotor and double-winding cylindrical linear generator, belongs to the field of linear generators for wave power generation and aims at solving the problem that an existing direct-driven wave power generation system is relatively poor in power generation quality. The magnetic field modulation principle-based double-rotor and double-winding cylindrical linear generator comprises a casing, a double-winding stator, a permanent-magnet rotor, a modulation rotor, a permanent-magnet rotor output shaft and a modulation rotor output shaft, wherein the double-winding stator is fixed on the inner circle surface of the casing; the modulation rotor and the permanent-magnet rotor are sequentially arranged in the double-winding stator from outside to inside; the permanent-magnet rotor is fixed on the permanent-magnet rotor output shaft; the modulation rotor is located between the double-winding stator and the permanent-magnet rotor; two ends of the modulation rotor extend outside from end covers at two sides of the casing separately; the extension part at the left side is taken as the modulation rotor output shaft; and the axis of the modulation rotor output shaft overlaps with that of the permanent-magnet rotor output shaft.

The invention provides a dual-sliding mode control based speed regulating system and method for direct torque of a permanent magnet synchronous motor main axis. The speed regulating method comprises the following steps: calculating the torque of the motor main axis according to the difference value of the actual rotating speed of the permanent magnet synchronous motor main axis and the given rotating speed of the permanent magnet synchronous motor main axis as a given value of a PI regulator; detecting the stator current and voltage of the motor main axis by using a sensor, observing the fluxlinkage and torque of the motor main axis under a stator coordinate system, comparing observed values with the torque calculated by the PI regulator and the given flux linkage respectively, obtainingdirect axis voltage and quadrature axis stator voltage by using the difference value through a dual-sliding mode controller, acting on a power switch device on a main circuit inverter through coordinate conversion and SVPWM conversion, and thus realizing direct torque control of the permanent magnet synchronous motor main axis. The speed regulating system is simple in structure, easy to realize and good in robustness, and has the advantages of high torque response speed and small tracking error, so that the stability of the system and the machining precision of parts are improved.

A device for use in an air intake path of an internal combustion engine to improve the engine performance. The device body has a top surface, bottom surface and at least one air passage defined about an axis from the top surface-to the bottom surface, containing a chamfer at each end. The upper portion of the passage surface contains a plurality of V-shaped veins about the axis of the passage. The lower portion of the passage narrows in diameter to a point equal to or greater than the vein extension in the upper portion. The lower portion also defines a grooved surface starting at it's beginning having a 60 degree slope edge and a flat bottom major diameter spaced in such a manner as to have a helical shape and to circumscribe the passage wall terminating prior to the end of the lower passage.

The application relates to a microgrid frequency control method and a microgrid system. The method includes the steps: acquiring a power of a common connection point between a load and a power grid; calculating a feedforward power of each inverter in a micro network according to the power of the common connection point; connecting the common connection point between the load and the power grid with the micro network; issuing the feedforward powers for adjusting the output frequencies of the inverters to the corresponding inverters in the micro network. According to the invention, the micro network is connected with the common connection point between the load and the power grid; after the power of the common connection point between the load and the power grid is obtained, the feedforwardpowers of all inverters in the micro network are calculated based on the power of the common connection point; and then the feedforward powers are issued to the corresponding inverters in the micro network and the feedforward powers are used for adjusting the output frequencies of the inverters. The feedward powers are obtained by collecting the power of the common connection point and thus the inverters adjust the own outputs and the output frequencies are adjusted in real time, so that the constant frequency of the system is kept and the stability of the system is kept.