36results about How to "Small harmonic distortion" patented technology

The invention discloses a large-scale electric vehicle trunking system based on MMC and a control method thereof. The large-scale electric vehicle trunking system is characterized in that three phase elements composed of an electric reactor, an H-bridge module and a sub-module are connected to an alternating current power grid through an LC filter to form a topological structure of the large-scale electric vehicle trunking system based on MMC, virtual electrical charge states are calculated through the initial electrical charge state, user set standing time and expected electrical charge state of each electric vehicle, the sub-module of the electric vehicle corresponding to a driving signal generated by each carrier signal is determined according to the ranking of the virtual electrical charge states, the differentiation control for electric vehicle charging and discharging power connected to the sub-modules according to user requirements is realized, and the control for three-phase power balance and unit power factors on a power grid side is realized. The system is high in integration degree, high in modularization degree, high in efficiency, little in harmonic distortion, low in switching loss and high in fault-tolerant capacity, and independent control for the sub-modules in each-phase bridge arms can be realized.

The present invention relates to an SVPWAM modulation method based on a three-level direct matrix converter. The method comprises the following steps: (1) determining input phase current space vectors and output phase voltage space vectors desired by a three-level direct matrix converter; (2) performing virtualization of the three-level direct matrix converter to a serial circuit model comprising a virtual rectification stage and a virtual inversion stage; (3) employing SVPWAM modulation for the virtual rectification stage to determine switching signals of each switch tube of the virtual rectification stage; (4) employing the SVPWAM modulation for the virtual inversion stage to determine switching signals of each switch tube of the virtual inversion stage; and (5) converting the switching signals of each switch tube of the virtual rectification stage and the switching signals of each switch tube of the virtual inversion stage to switching signals of each two-way switch of the three-level direct matrix converter. Compared to the prior art, the number of off and on times is maximally reduced, switching loss is reduced, the harmonic wave content of an input current is reduced, and the quality of a power grid is improved.

The invention belongs to the field of power converter control, and discloses a three-phase current transformer model prediction control method free from a voltage sensor. The method comprises the following steps: 1, sampling AC-side currents and DC-side voltages of a current transformer; 2, performing integration on network-side voltages of the current transformer under an alpha-beta coordinate system, then after a low-pass filtering link, together with power grid currents i<alpha> and i<beta>, observing AC network-side virtual magnetic linkages (phi<alpha>, phi<beta>); 3, according to the observed virtual magnetic linkages phi<alpha> and phi<beta>, reconstructing power grid voltages and calculating magnetic linkage space angles; 4, based on a voltage outer loop, by use of model prediction control, through a solving algorithm of secondary planning, calculating optical voltage instructions (v<d><*>,v<q><*>); and 5, obtaining driving signals of a power switch tube after the voltage instructions pass through dq/alpha beta and then is subjected to an SVPWM algorithm. According to the invention, under the condition that an AC-side voltage transducer is omitted, the provided current transformer model prediction control algorithm performs searching optimization by use of a secondary planning solving algorithm, such that the system reliability is improved, the computational complexity is reduced, the difficulty of parameter setting is reduced, and the realization is easy.

A variable-gain amplifier with a differential input and differential output, including an attenuator block, receiving an input voltage and providing, on several outputs, voltages, each of which is equal to the attenuated input voltage; differential transconductor elements, each having a first input connected to a respective output of the attenuator block, and generating first and second positive currents and first and second negative currents; a current source assembly adapted to controlling the transconductance of each differential transconductor element according to an analog control signal; and an output block converting first and second input currents into a differential output voltage and providing a second input of each differential transconductor element with a feedback voltage depending on the output voltage.

The invention discloses a power regulation device based on controlled silicon. According to the required power, a conduction angle alpha is regulated to be varied in the range of 0-pi, thus the output voltage can be continuously regulated in the range of a second-level voltage and a first-level voltage. The invention can realize continuous regulation of the load voltage value by using the power regulation device based on the controlled silicon and reduce the system oscillation. The fact that the invention can generate smaller harmonic distortion (THDu) compared with the phase-shift power regulation can be discovered by Matlab emulation. The small harmonic distortion (THDu) indicates that harmonic component is restrained and power factors are improved, thereby reducing pollution to power grid.

The invention provides a digitalized three-phase system power factor correction apparatus and a correction method. The digitalized three-phase system power factor correction apparatus comprises a power factor correction main circuit, a PFC controller, a PFC driver and an LCD display screen, wherein the power factor correction main circuit comprises an LCL three-phase filter, a three-phase six-switch full-bridge rectification circuit and a DC filtering capacitor, and the PFC controller comprises a simulation voltage and current signal acquisition module, an algorithm processing module and a digital modulation pulse output module. The algorithm processing module employs a digitalized mode to realize full-decoupling control, the digital modulation pulse output module generates spatial vector modulation pulses according to the output result of the algorithm processing module by using a digitalized pulse-width modulation method to complete driving of three-phase six switches. The power factor is high, the input current harmonic wave distortion is small, the efficiency is high, bidirectional transmission of power can be realized, and the digitalized three-phase system power factor correction apparatus is suitable for large-power occasions.

The invention discloses a thirteen-segment carrier pulse width modulation method and system and related components, relates to the field of carrier pulse width modulation, is applied to a three-level converter, and comprises the following steps: sorting three instantaneous voltage values of a three-phase sine wave; according to the maximum voltage value, the intermediate voltage value and the minimum voltage value, determining a dual-modulation wave parameter of the corresponding phase; determining an upper modulation wave and a lower modulation wave of the corresponding phase according to the dual modulation wave parameter of each phase; and comparing the upper modulation wave, the lower modulation wave and the triangular carrier wave of each phase to generate a driving signal of the corresponding phase. The driving signal output by the modulation method can ensure that the phase voltage pulse width of a low modulation degree region is greater than the minimum switching time of a device, so that narrow pulses are effectively eliminated, the target voltage is accurately output, and the effects of reducing current harmonic distortion and improving neutral-point voltage self-balance of the three-level converter are achieved. In addition, only amplitude calculation is needed, and the method has the advantages of being simple in calculation and easy to implement.

The invention discloses a grading frequency conversion type multipath series resonance inverter power supply. The grading frequency conversion type multipath series resonance inverter power supply comprises a rectification transformer, a three-phase full bridge phase control rectifier, an LC filter, an H-bridge inverter, a matching transformer, a load coil and n parallelly-conected grading frequency conversion units, wherein each grading frequency conversion unit comprises a charge bleeder, a resonant capacitor and a switching switch, the charge bleeder is in parallel connection with the resonant capacitor, one end of the charge bleeder is connected with the matching transformer, and the other end is connected with the load coil. The inverter power supply is advantaged in that through switching different grading frequency conversion units and matching the corresponding H-bridge inverter driving frequency, grading frequency conversion operation of the power supply is realized; residual charges in the resonant capacitor can be released in the quite short time, DC bias borne by the switching switch is timely eliminated, and over-voltage burning of the switching switch can be prevented; the switching switch is controlled through employing a synchronization triggering strategy and a synchronization switching strategy, the control strategies are simple, seamless switching of output current frequency of the power supply is guaranteed, and current harmonic distortion is small.

The invention belongs to the LED driving field and discloses a bluetooth color-temperature-adjusting LED driving power supply. An input end is in forward connection with a diode V1 and a diode V2; theoutput ends of the diode V1 and the diode V2 are connected with the drain electrode of a field-effect tube V1; each light-emitting LED group is provided with light-emitting LEDs connected in series in sequence; the TXD pin of a bluetooth module is connected with the P3.0 pin of a single-chip microcomputer, and the RXD pin is connected with the P3.1 pin; the output pins P1.0, P1.1, P1.2 and P1.3 of the single-chip microcomputer are connected with the same-phase input end of a corresponding amplifier; the same-phase input end of the amplifier is connected with the control electrode of a corresponding field effect transistor V2; the source electrode of the field effect transistor V2 is grounded through a resistor R1; each group of light-emitting LED group is connected with the output end ofan inductor L1; and the output end of each group of light-emitting LED group is connected with the drain electrode of the field effect transistor V2. The driving power supply is high in circuit stability and high in driving power supply efficiency, realizes wireless remote adjustment through a bluetooth, is convenient and fast and is high in practical value.

The invention discloses an SVPWM (Space Vector PWM) control method, system and device for eliminating a dead zone effect, which are applied to an NPC multi-level converter. The method comprises the steps of: obtaining three sub-vectors used for synthesizing a target voltage vector, determining the action time proportion of the three sub-vectors and the corresponding switch state thereof, and obtaining an initial comparison value of each phase in three phases according to the action time proportion and the switch state; according to the current direction of each phase in the three phases and the slope of a triangular carrier, correcting the initial comparison value by using a preset correction amount to obtain a corrected comparison value; comparing the corrected comparison value of each phase in the three phases with the triangular carrier to obtain a corresponding comparison result; and logically processing each phase according to the comparison result of each phase to generate the SVPWM pulse. By using the SVPWM pulse obtained by the invention, a relatively ideal sine wave output voltage can be obtained, the total harmonic distortion of the output current is obviously reduced, and the impact on a load or a power supply network is avoided.

A circuit arrangement for operating a discharge lamp with a high frequency current comprising input terminals for connection to a source of low frequency supply voltage, a rectifier bridge coupled to the input terminals for rectifying the low frequency supply voltage, and an inverter shunting a first capacitor for generating the high frequency current. The circuit arrangement incorporates two power feedback loops to feed power back to an output terminal of the rectifier bridge. As a result the circuit arrangement has a relatively simple configuration, causes only a very limited amount of harmonic distortion and can be realized with relatively cheap and simple components.\!

The invention discloses a PWM (Pulse-Width Modulation) rectifier control method and a PWM rectifier control device based on model prediction control. The PWM rectifier control method comprises the following steps: calculating and predicating active power and reactive power of the next moment; combining the model prediction control and direct current control; taking a negative value conjugated with complex power in a prediction model as a variable, and judging a sector of the variable for one time by adopting a rapid vector selection method to obtain an optimal voltage vector; dividing the judged sector into two small parts by taking the position of a reference complex power vector as the standard; selecting a suboptimum voltage vector according to the position of the reference complex power vector; and calculating acting time of the optimal voltage vector and the suboptimum voltage vector in a control period to obtain a driving signal of a switching tube. The invention further discloses a PWM rectifier control method based on the model prediction control. The PWM rectifier control method and the PWM rectifier control device provided by the invention have the characteristics of small calculation amount, easiness in realization, rapid dynamic responses, good stable-state performance and the like.