13results about How to "Improve harmonics" patented technology

The invention discloses a new energy grid-connected three-level inverter midpoint potential balance modulation method and system, and the method comprises the steps: carrying out the sector judgment and reference voltage vector mapping of three-phase reference voltages va, vb and vc from a controller; calculating an optimal switching waveform and time parameters da1, db1 and dc1 thereof according to the mapped three-phase reference voltages va1, vb1 and vc1, the sampled midpoint potential deviation V1-V2 and the three-phase current iabc, and reflecting the time parameters da1, db1 and dc1 into time parameters da, db and dc of each phase waveform of an original voltage sector; and inputting the time parameters da, db and dc of each phase waveform of the original voltage sector into a modulator to generate a modulation signal so as to control the three-level inverter. The invention aims at suppressing the neutral-point potential fluctuation of the new energy grid-connected three-level inverter and reducing the current harmonic wave and the switching loss at the same time.

The invention provides a circuit structure, an air conditioning system and a control method, and the circuit structure comprises a bus circuit which is provided with a load; the voltage reduction assembly is connected with the bus circuit; the pressure reduction assembly comprises a control part; the control module is in signal connection with the control part, and the control module controls the bus circuit to be connected or disconnected through the control part; when the control part controls the bus circuit to be connected, the bus circuit charges the voltage reduction assembly; when the control part controls the bus circuit to be disconnected, the voltage reduction assembly supplies power to the bus circuit, and the circuit structure solves the technical problem that the voltage withstanding requirement of parts on the bus of the inverter circuit is high.

This invention relates to the field of inverter technology, and particularly to a heterogeneous power device hybrid inverter and its space vector modulation method. The heterogeneous power device hybrid inverter provided in this invention includes a first constant current source, a second constant current source, a main power inverter module, a secondary power inverter module, and a capacitive reactance module. The first constant current source is connected to the main power inverter module to provide current to the main power inverter module. The main power inverter module includes multiple silicon-based insulated-gate bipolar transistors (SBMTs) as main switching transistors, and the main power inverter module is connected to the capacitive reactance module. The second constant current source is connected to the secondary power inverter module to provide current to the secondary power inverter module. The secondary power inverter module includes multiple silicon carbide-based metal-oxide-semiconductor field-effect transistors (MOSFETs) as secondary switching transistors, and the secondary power inverter module is connected to the capacitive reactance module. The heterogeneous power device hybrid inverter and its space vector modulation method provided by this invention can balance high inverter frequency and low switching losses.

The invention belongs to the technical field of string adjustment, and particularly relates to a violin string tension adjustment control device which comprises an adjustment chamber, adsorption units are symmetrically arranged at one end of the adjustment chamber, positioning units are arranged on the sides, close to the adjustment chamber, of the adsorption units, an adjustment unit is arranged on one side in the adjustment chamber, and a feedback unit is arranged on one side of the adjustment unit. Through the lifting effect of the electric telescopic rod and the face-to-face or back-to-back movement between the idler wheels, lifting and sudden release of strings are achieved, then radial jumping of the strings is degraded and buffered through the multi-degree-of-freedom string roller, dominant impact between the lower electrode cap and the electrode ball is controlled through the prying roller short section, and therefore the electrode ball can be driven to move stably and stably. The high-frequency impact state between the strings and the long section of the prying roller is expressed, that is, impact feedback of the strings in a low-frequency state is explicitly and prominently expressed through an extended range, the change of tension is accurately sensed, excessive or insufficient adjustment is avoided, the overall tone balance is optimized, and the harmony degree and expressive force of the tone of the violin are improved.

This invention relates to the field of electric motors, and more particularly to an electric motor rotor. The electric motor rotor includes: a trapezoidal slot formed on the outer circumferential surface of the motor rotor, the trapezoidal slot having a base edge; a magnet slot, the axis of symmetry of the magnet slot passing through the center of the inner diameter of the motor rotor, the trapezoidal slot being formed on at least one side of the axis of symmetry of the magnet slot, the magnet slot having a first side line; and a magnetic stabilizing hole formed between the outer circumferential surface of the motor rotor and the magnet slot, the longitudinal axis of the magnetic stabilizing hole being perpendicular to the first side line, the magnetic stabilizing hole and the trapezoidal slot being on the same side of the axis of symmetry of the magnet slot, the axis of symmetry of the trapezoidal slot passing through the center of the inner diameter of the motor rotor, an angle α1 between the longitudinal axis of the magnetic stabilizing hole and the axis of symmetry of the trapezoidal slot, and an angle α2 between the longitudinal axis of the magnetic stabilizing hole and the axis of symmetry of the magnet slot, α1 and α2 satisfying 0.701≤(α1-α2) / α1≤0.958. This invention also relates to an electric motor. This invention can effectively reduce the no-load back EMF harmonics of the motor, improving motor efficiency and operational smoothness.

The invention discloses a PFC current feedback control method and device based on average current detection, and the method comprises the steps: obtaining a first inductive current ADC sampling value at a carrier zero point and a second inductive current ADC sampling value at a carrier vertex, calculating a current current difference value between the two sampling values, and determining a target current value interval corresponding to the current difference value; and obtaining a current target current control strategy corresponding to the target current value interval, determining a current average current in combination with the first inductive current ADC sampling value and the second inductive current ADC sampling value, and taking the current average current as a feedback quantity of a target control loop. According to the embodiment of the invention, the target current value interval and the corresponding current target current control strategy are determined by calculating the difference between the first inductive current ADC sampling value at the carrier zero point and the second inductive current ADC sampling value at the carrier vertex, and the more accurate current average current is determined based on the current target current control strategy. And input current harmonic increase is avoided.

The present invention relates to a dead zone compensation method for a three-level DC-AC converter considering an output filter, and its technical characteristics are: an IGCT three-level power device is considered together with a dv / dt filter connected to its AC side, so as to achieve more accurate compensation of the dead zone time. The specific method is to analyze a certain phase of the IGCT three-level converter, establish a frequency domain transfer function model and obtain a corresponding current time domain function according to the influence of the LCR filter circuit on the output phase voltage; calculate the maximum change value of the current; collect the load current in the equivalent topology, judge the relationship between the load current and the maximum change value of the current, calculate the dead zone equivalent area and obtain the dead zone compensation time, and introduce it into the output voltage to achieve compensation. The present invention is reasonably designed, takes into account the influence of the LCR filter circuit on the nonlinear dead zone effect, solves the problem that the conventional dead zone compensation method is poorly compensated at the current zero crossing, improves the accuracy of the dead zone compensation, and greatly improves the current harmonics on the AC side.

The utility model discloses a low-ripple and low-harmonic power supply charger. The internal circuit comprises a commercial power input and over-current protection circuit, an EMI filtering electromagnetic anti-interference circuit, a harmonic improvement circuit, a rectification filter circuit, a PWM control IC and MOSFET tube driving circuit, a high-frequency transformer conversion circuit, an output rectification filter circuit, an MCU protection and charging control circuit, a loop control circuit, a load short circuit prevention and reverse insertion circuit and an output low ripple and EMI circuit. According to the lead-acid battery power supply charger of the utility model, the EMI filtering electromagnetic anti-interference circuit, the harmonic improvement circuit, the output rectification filter circuit and the output low ripple and EMI circuit are designed, and the high-frequency transformer is adopted, so that the power supply charger is provided with a multi-stage ripple and harmonic suppression circuit, and therefore, ripple and harmonic generated in the charger can be improved and suppressed; working stability and power supply efficiency of the power supply charger are ensured.

The utility model relates to the field of non-linear inductors, discloses an inverter inductor and an inverter, and aims to solve the problems that in the prior art, harmonic waves under light loads cannot be improved due to the fact that the inductance value under light loads is difficult to independently pull up under the condition that the inductance value under heavy loads is difficult to keep unchanged after materials of the inverter inductor are determined. According to the technical scheme, the secondary magnet yoke of which the magnetic flux density is smaller than that of the primary magnet yoke is added to be connected with the primary magnet yoke in parallel in the magnetic flux direction, so that the magnetic flux mainly passes through the secondary magnet yoke under the condition that the coil is connected with a light load, and as the magnetic resistance of the secondary magnet yoke is small, the coupling coefficient between the two windings formed by the coil and the middle column is large; therefore, the inductance value of the inversion inductor under the light load is greatly improved. Along with the increase of the load, when the secondary magnet yoke is saturated, the magnetic flux starts to pass through the primary magnet yoke, so that the inductance value of the inversion inductor can keep the nonlinear characteristic of the primary magnet yoke. According to the technical scheme, the sensing value during light load is increased under the condition that the sensing value during heavy load is not changed, and the THDI problem under the light load is effectively solved.

The present disclosure belongs to the technical field of permanent magnet synchronous motor control, and particularly relates to a kind of permanent magnet synchronous motor position sensorless control method and system, comprising: obtaining the stator current and stator voltage of permanent magnet synchronous motor, respectively calculate the first active flux linkage based on voltage model and the second active flux linkage under current model;The first active flux linkage and the second active flux linkage obtained are calculated to match error and inverter output voltage compensation term;According to the output voltage compensation term obtained, the driving signal of inverter is adjusted to realize the driving control of permanent magnet synchronous motor.The present disclosure identifies and compensates by constructing an adaptive observer, improving the running performance of the model method based on flux linkage at low speed.

The present invention discloses a PFC current feedback control method and device based on average current detection, which obtains the first inductor current ADC sampling value at the carrier zero point and the second inductor current ADC sampling value at the carrier vertex, calculates the current current difference between the two and determines the corresponding target current value interval; obtains the current target current control strategy corresponding to the target current value interval, and determines the current average current in combination with the first inductor current ADC sampling value and the second inductor current ADC sampling value, and uses it as the feedback amount of the target control loop. The embodiment of the present invention determines the target current value interval and the corresponding current target current control strategy by calculating the difference between the first inductor current ADC sampling value at the carrier zero point and the second inductor current ADC sampling value at the carrier vertex, and determines a more accurate current average current based on the current target current control strategy to avoid the increase of input current harmonics.

The invention discloses a PFC circuit and a control method thereof, a computer readable storage medium and refrigeration equipment, and the control method comprises the steps: controlling the PFC circuit based on an interval period control mode, so as to determine the duty ratio information of the PFC circuit in each control period; and when it is determined that the PFC circuit works in the discontinuous current mode according to the duty ratio information, the carrier control frequency of a switching tube in the PFC circuit is improved, so that the PFC circuit works in the continuous current mode. According to the method, when it is determined that the PFC circuit works in a discontinuous current mode according to duty ratio information of a control period, the PFC circuit works in a continuous current mode by improving the carrier control frequency of a switching tube in the PFC circuit, so that inductive current distortion is reduced, power factors and harmonic waves during light-load operation are improved, and the efficiency of the PFC circuit is improved.

The invention relates to the technical field of image enhancement, and provides an underwater image dual-path enhancement method based on wavelet domain diffusion and spatial domain collaboration, which comprises the following steps: acquiring and preprocessing an original underwater image, performing multi-stage discrete wavelet transform on each image, and decomposing to obtain a low-frequency component and a multi-layer high-frequency component; performing frequency domain enhancement on the low-frequency component and the multiple layers of high-frequency components, and outputting a frequency domain enhanced image; inputting the original underwater image into the spatial domain residual mapping network for color and contrast correction to obtain a spatial domain enhanced image; performing adaptive fusion on the original underwater image, the frequency domain enhanced image and the spatial domain enhanced image to generate a pixel-by-pixel weight and a global weight, performing weighted fusion on a frequency domain enhanced result and a spatial domain enhanced result based on the pixel-by-pixel weight and the global weight, and outputting a final enhanced image; and loading the trained model, and outputting a final enhanced image. According to the invention, high-quality integrated recovery of underwater image colors, illumination and details is realized.