89results about How to "Suppress harmonic current" patented technology

The invention relates to a permanent-magnet synchronous motor torque ripple suppression method based on coordinate transformation harmonic compensation. Three-phase current is acquired and converted into stator current in a two-phase static coordinate system; the stator current in the two-phase static coordinate system is transformed to fifth, seventh, eleventh and thirteenth harmonic rotating coordinate systems; direct-current component is extracted from fifth, seventh, eleventh and thirteenth harmonic current in the corresponding coordinate systems through a low-pass filter; a second-order low-pass digital filter based on speed adaptation is designed to extract harmonic of a specific order; and on the basis, a proportional integral current controller with cross coupling is designed to complete harmonic current suppression ultimately, thus suppressing torque ripple. Compared with the prior art, the harmonic content of output current can be reduced, and torque ripple, vibration noise and other negative effects of a permanent-magnet synchronous motor for electric vehicles can be reduced on the basis of permanent-magnet synchronous motor vector control.

The invention relates to a harmonic current suppression method for a magnetic suspension rotor system based on a self-adaptive repetitive controller. The harmonic current suppression method comprises the following steps: firstly establishing dynamical models for the active-passive magnetic suspension rotor system containing unbalance and sensor harmonic waves, secondly designing the self-adaptive repetitive controller, and giving out the harmonic current suppression method according to the characteristics of the active-passive magnetic suspension rotor system. The method is suitable for harmonic current suppression of an active magnetic bearing coil of the active-passive magnetic suspension rotor under the condition that unbalance mass and the sensor harmonic waves exist, and is high in precision and high in rate of convergence.

The photovoltaic and wind-power uniform interconnected equipment with reactive compensation and harmonic wave processing comprises: at least a clean energy power, at least one power modualtor, a dc busbar loop, a three- or four-phase multilevel inverter, one three- or four-phase interconnected reactor, a three- of four-phase breaker, and a data collection and logic controller. This invention can interconnect both the photovoltaic power and wind-power source, and every power can realize the maximal power point track. This invention can compensate the harmaci wave in 0-30 times.

A current control unit takes a deviation between a current command value and a current flowing through an inverter of a power conversion device, and controls the inverter based on the deviation. A harmonic sensing part receives input of an output current of an AC filter, and outputs a predetermined order harmonic of the input current in a direct current value form. A disturbance observer estimates the disturbance of the harmonic based on the output current and a coefficient defined as an inverse function of a transfer function from harmonic suppression current command value to filter output current detection value. A harmonic suppression control unit takes the deviation between the estimated harmonic disturbance and a disturbance command value that suppresses the disturbance, and calculates a harmonic suppression current command value. The harmonic suppression current command value is superimposed on the current command value of the current control unit.

The invention discloses a magnetic suspension rotor harmonic current suppression method based on an FIR filter and a fractional-order repetitive controller. The method comprises the steps: firstly, a magnetic suspension rotor dynamic model containing mass unbalance and sensor harmonic wave is established; then, the FIR filter is a low-pass filter with the linear phase characteristic, and the fractional-order repetitive controller can be obtained through approximation of a fractional delay filter. The method provided by the invention can achieve harmonic current suppression in a constant rotation speed through online updating of the fractional delay filter and is suitable for harmonic current suppression of a magnetic suspension rotor with mass unbalance and sensor harmonic wave; the FIR low-pass filter and the fractional-order repetitive controller are combined and used, and the harmonic current suppression can be achieved through the linear phase characteristic of the FIR filter and the online updating of the fractional-order repetitive controller.

The invention discloses a mixed induction type active electric power filter system. The mixed induction type active electric power filter system comprises a rectifier transformer, a filtering branch, a rectifier and the other filtering branch, wherein the other filtering branch comprises three passive filters and a voltage source inverter, the passive filters are connected to the voltage source inverter, the primary side of the rectifier transformer is connected to a three-phase power grid through connecting impedor, an epitaxy winding of the secondary side of the rectifier transformer is connected with the rectifier, and the passive filters are connected to three junction points between a delta winding and the epitaxy winding of the secondary side of the rectifier transformer in parallel respectively. According to the mixed induction type active electric power filter system, influence of frequency fluctuation of the power grid side and the high-capacity nonlinear load side on electric power filtering performance is eliminated; meanwhile, the problems that serious harmonic pollution, high additional loss of a master device, high vibration and noise, low system power factor and low system operation efficiency are caused by harmonic waves and idle work to an industrial power distribution and consumption system are effectively solved on the premise that electric power quality on the power grid side meets the national standard of China.

The invention provides an alternating current (AC) hybrid active power filter system for high-voltage direct current (DC) transmission, and a control method of the AC hybrid active power filter system. The AC hybrid active power filter system is applied to a high-voltage DC transmission system, and comprises a passive power filter and an active power filter which are connected with each other, wherein an output end of the passive power filter is directly connected with AC sides of convertor stations at two ends of a high-voltage DC output power system; the passive power filter comprises three groups of single-tuned passive filters, wherein each group of single-tuned passive filter is correspondingly connected with one phase of the AC sides of the convertor stations; the single-tuned passive filter groups have a series resonance characteristic; the active power filter comprises a modular multi-level converter and a controller connected with the modular multi-level converter; a DC end of the modular multi-level converter is connected with a capacitor in parallel. After the AC hybrid active power filter system and the control method of the system are adopted, the equipment investment and the operation and maintenance cost are effectively reduced, the electric energy loss generated by unit capacity can be reduced, and the economy of a high-voltage DC transmission AC filtering device can be improved.

The invention discloses a power supply method and a charging device for a super capacitor energy storage type trolley car, the power supply is that when a tram with on-board supercapacitors arrives atthe station, The pantograph is powered from the DC / DC chopper to the on-board supercapacitor. DC energy is output to DC / DC chopper after AC / DC converter rectifies 380V three-phase AC input from powergrid, and DC energy is output to DC / DC chopper by ground supercapacitor. The vehicle-mounted supercapacitor is charged after pantograph is fully charged. The DC / DC chopper stops charging the vehicle-mounted supercapacitor when the vehicle-mounted supercapacitor is fully charged or when the tram leaves the station. The output switch of the DC / DC chopper is turned off and the pantograph is loweredback. The AC / DC converter switches to the ground supercapacitor to charge the ground supercapacitor so as to obtain the continuous replenishment of the pre-stored DC energy. The invention has the advantages of improving the survival rate of the trolley, reducing the capacity dependence on the power supply network and the impact on the power supply network, and reducing the construction and operation cost.

The invention discloses a second-order-odd-repetitive-controller-based odd harmonic current suppression method of a magnetic levitation rotor. A magnetic levitation rotor kinetic model including rotor mass unbalance and sensor harmonic is established; and a second-order-odd-repetitive-controller(SOORC)-based odd harmonic current suppression method of a magnetic levitation rotor is employed. The SOORC has a second-order inner membrane structure for odd harmonic frequency suppression, so that the harmonic suppression capability on a harmonic frequency changing or uncertain condition can be improved and thus the control robustness of the system for the harmonic frequency changing or uncertain condition can be improved. With phase hysteresis-lead compensation, the steady performance and dynamic performance of the system are improved, so that odd harmonic current components generated by a magnetic bearing coil in a magnetic levitation rotor can be suppressed. The method is suitable for suppression of odd harmonic current components of the magnetic levitation rotor system with rotor mass unbalance and sensor harmonic.

The invention discloses a multi-step model forecast control-based circulation control method of a modular multilevel converter (MMC). The circulation control method comprises the following steps of firstly, performing dead beat control by an AC output current of the MMC to obtain reference input module numbers of an upper bridge arm and a lower bridge; secondly, performing single-step circulation forecast by combining a circulation current discrete state equation; thirdly, selecting the input module number conforming to a single-step forecast effect, and performing multi-state circulation forecast; and finally, solving an optimal solution of the bridge arm input module number, and achieving multi-step optimal control of a circulation current so that a harmonic current in the circulation current is effectively suppressed. The circulation control method comprises AC dead beat control, circulation single-step forecast and circulation multi-step forecast. Aiming at the circulation harmonic current of the MMC, a multi-step forecast finite control set is built by a multi-step model forecast control method according to the optimal solution obtained by single-step forecast, the cycle forecast frequency required by multi-step forecast can be substantially reduced, and the calculation quantity of a controller is effectively reduced.

The invention discloses a magnetic suspension rotor harmonic current inhibition method based on parallel FORC and phase lag-lead compensation, and the method comprises the steps: firstly building a magnetic suspension rotor dynamical model comprising quality imbalance and sensor harmonic; secondly employing a magnetic suspension rotor harmonic current inhibition method based on a parallel FORC structure. The structure enables internal models of a harmonic at all frequencies to be converted into a plurality of parallel units with the similar structures, and quickly improves the dynamic performances of a system. The method also employs the phase lag-lead compensation to improve the stability and dynamic performances of the system. The invention proposes a method for quickly and adaptively adjusting the controller gain for a specific harmonic signal. The method achieves the dynamic optimization of the dynamic performances and stability. The method achieves the inhibition of a harmonic component of a current of a magnetic bearing coil in a magnetic suspension rotor, and is suitable for the harmonic current inhibition of the magnetic suspension rotor system with the quality imbalance and sensor harmonic.

The invention discloses a space vector pulse width modulation method for a six-phase variable-frequency power source, which comprises the following steps 1), a six-phase / two-phase coordinate transformation matrix is used for mapping sixty-four switching states of a six-phase voltage source inverter to a dq sub-plane, a z1z2 sub-plane and an o1o2 sub-plane, and sixty-four fundamental voltage space vectors are obtained, wherein four zero vectors are included in the sixty-four vectors; 2), twelve vectors with the maximum amplitudes in the sixty-four vectors are selected from the dq sub-plane, and twelve new vectors are constructed according to a principle that voltseconds of the z1z2 sub-plane and o1o2 sub-plane are zero; 3), expected vectors are synthesized in the dq sub-plane by using the twelve new vectors and the zero vectors, and the action time of fundamental vectors corresponding to the new vectors is determined; and 4), action sequences of the fundamental vectors corresponding to the new vectors are determined according to a design principle that the switching times of the six-phase voltage source inverter is least and an output voltage waveform is in a 1 / 2 periodically symmetrical state. The method can be applied to modulation of the output voltage waveform of a multi-phase variable-frequency power source; the switching loss of the inverter can be reduced; load harmonic current can be inhibited.

The invention provides an AC-DC converter with bidirectional energy flow, belonging to the technical field of a transformer. The AC-DC converter comprises a voltage reduction circuit and a rectifier circuit, wherein an output terminal of the voltage reduction circuit is connected with an input terminal of the rectifier circuit; the high-voltage working-frequency alternating-current voltage is converted into the low-voltage working-frequency alternating-current voltage by the voltage reduction circuit; and the low-voltage working-frequency alternating-current voltage is converted into the low-voltage direct-current voltage by the rectifier circuit. The AC-DC converter can realize the conversion between the high-voltage alternating-current voltage and the low-voltage direct-current voltage, has four quadrant capability of an unit input power factor and the bidirectional energy flow, has a simple structure in whole, and enables the whole performance to be more perfect.

The embodiment of the invention discloses a control system and method for suppressing current harmonics of a permanent magnet synchronous motor. The control system comprises a current sampling modulewhich samples a three-phase current in real time; a current coordinate transformation module which is used for transforming current coordinates; a low-pass filtering processing module which is used for processing a DC component; a fuzzy control decision module which is used for performing calculating to obtain a harmonic compensation voltage; a voltage coordinate conversion module which is used for converting harmonic compensation voltage coordinates; a harmonic compensation voltage injection module which is used for superposing a reference voltage to obtain a final reference voltage signal; and an SVPWM module which modulates the final reference voltage signal and injects the final reference voltage signal into the motor. According to the method, a fifth harmonic component and a seventh harmonic component in a current fundamental wave can be detected in real time, the corresponding harmonic compensation voltages are calculated and injected into a final reference voltage vector, so theeffect of suppressing the current harmonic of the permanent magnet synchronous motor is achieved, the fuzzy control strategy has higher robustness for a nonlinear time-varying system, and the controlperformance of the motor is further improved.

The invention discloses a harmonic cancellation PWM generation method, and the method comprises the steps: dividing the modulation frequency into three parts in a variable frequency speed regulation range: first and second low-frequency operation stages and a middle-high frequency operation stage; respectively an SVPWM asynchronous modulation mode and an SVPWM synchronous modulation mode, which are fixed through employing carrier frequency, at the first and second low-frequency operation stages; carrying out the frequency point control of the above two modulation modes when the synchronous carrier frequency and the set asynchronous carrier frequency are consistent; enabling the second low-frequency operation stage to be carried out at a plurality of different synchronization multiples; employing a mode of dividing each cyclic wave into a plurality of executed harmonic waves equally to eliminate an SHEPWM mode at the middle-high frequency operation stage; reading a current angle before switching, and calculating the time delay when operating to 90 degrees or 270 degrees so as to achieve the switching between the synchronous modulation mode and a harmonic cancellation mode. The method is easier to implement a specific harmonic cancellation algorithm, and increases the response speed and precision.

The invention discloses a magnetic suspension rotor vibration harmonic suppression method and a magnetic suspension rotor vibration harmonic suppression system with multiple wave traps connected in parallel. The magnetic suspension rotor vibration harmonic suppression system comprises parallel phase-shift wave traps, a magnetic suspension controller and a magnetic bearing rotor which are connectedin sequence, wherein signal extraction points of the parallel phase-shift wave traps are placed at an input end of the magnetic suspension controller, and signal insertion points of the parallel phase-shift wave traps are placed at a position of a displacement error signal. The magnetic suspension rotor vibration harmonic suppression method and the magnetic suspension rotor vibration harmonic suppression system aim at the magnetic suspension rotor, considers the influence of rotor mass unbalance and sensor vibration, establish a magnetic suspension rotor dynamical model containing harmonic disturbance, effectively suppress different frequency disturbance components of a harmonic current under variable rotating speed frequency by connecting a plurality of differently phase-shifted wave traps in parallel, further effectively suppress the harmonic vibration while ensuring closed-loop stability of the system, and are of reference significance to the harmonic suppression problem under themagnetic suspension-rotor system under variable speed situation.

The invention discloses a three-phase four-switch APF switching control method based on Lyapunov. The method comprises the steps that a three-phase four-switch APF topological structure is analyzed first; a state equation of a switch function and the three-phase four-switch APF topological structure under a three-phase static coordinate system are established; a state equation of the three-phase four-switch APF topological structure under instruction currents is written, difference of the two state equations is achieved, an error state equation is obtained; voltages output in the three-phase static coordinate system under different switch modalities are converted into a two-phase static coordinate system; a controller is designed based on Lyapunov, on the basis of conversion of coordinates, the relationship between error currents and changing rate included angle thereof is analyzed under the two-phase static coordinate system, a switching rule which accords with the stability theorem is obtained; third, a control rule is obtained through the method, and connection and disconnection of a three-phase four-switch APF are controlled. Compared with a three-phase four-switch SVPWM algorithm, complex modulation processes are omitted through the method.

The invention provides a quasi-resonance converter adopting an LLCL-type filter and limiting a reverse recovery current. The quasi-resonance converter comprises an equivalent DC (Direct Current) power supply, a controllable capacitance branch circuit and a three-phase output converter, wherein an output end of the equivalent DC power supply is connected with an input end of a boosting converter, two ends of the three-phase output converter are connected with the output end of the boosting converter, one end of the controllable capacitance branch circuit is connected with a positive bus-bar end of the three-phase output converter, the other end of the controllable capacitance branch circuit is connected with a position output end of the equivalent DC power supply, and the three-phase output converter is provided with a filter in a connection manner and is communicated with a power grid or a load through the filter. According to the quasi-resonance converter provided by the invention, the problems of large DC voltage output range, softened switch, filtering output of the converter and the like of a renewable energy source power generation system during the application are comprehensively considered, the connection mode of the controllable capacitance branch circuit is changed, the withstand voltage of the controllable capacitance branch circuit can be greatly reduced, and thus the cost can be further lowered.

The invention discloses a six-phase motor harmonic current suppression method based on model predictive direct torque control, which includes the following steps: analyzing the vector requirements ofharmonic current suppression according to the characteristics of a voltage vector of a six-phase motor; making a vector selection table by considering the changes of torque and flux according to the vector selection rules of direct torque; selecting corresponding zero vectors according to the principle of minimum number of switching times, and making a zero vector correspondence table; deriving aprediction model of the motor from a mathematical model of the six-phase motor; and obtaining a simplified cost function according to the characteristics of model predictive direct torque control. Themodel predictive direct torque control method based on the scheme can suppress the harmonic current of the six-phase motor. The implementation process of the scheme is simple and easy, and the maximum voltage vector of the system can be fully utilized.

A power conversion device is configured by parallel connecting of chopper circuits (3a, 3b) which each include a reactor (4a, 4b), a switching element (5a, 5b), and a backflow prevention element (6a, 6b) and chop and boost the output of a rectifier (2) that rectifies the AC voltage from an AC power source (1), the power conversion device comprising: an AC switch (12) arranged closer to the AC power source (1) than the chopper circuits (3a, 3b); an AC reactor (13) arranged closer to the AC power source (1) than the chopper circuits (3a, 3b) and connected in parallel with the AC switch (12); and a switching control unit (10) for controlling the operation of the switching elements (5a, 5b) and the AC switch (12). When the contacts of the AC switch (12) are open, the switching control unit (10) suspends the switching of the switching elements (5a, 5b).

The present invention discloses a method of restrain the harmonic current of large power AC motor and consists of a DC power supply circuit, a waveform rectification circuit, a power output set circuit, a single chip microprocessor and a two-way controllable silicon moving phase control circuit. In continuous semiwave that follows one by one to supply the AC motor with voltage, different moving phase angle is used for slightly increasing the circuit value of even-numbered resonance wave and to greatly reduce the current of odd-numbered resonance wave. The boundary is to keep the resonance current value within EMC standard; when controlling the two-way controllable silicon moving phase, the phase angel can be moved according to the output power of the motor. Three different phase shifting angles of large, middle and small are adopted and the odd-numbered resonance waveform current value that is produced by restraining the work of motor uses the method of equalizing the medium value of the three phase shifting angles and the needed phase shifting angle. The present invention can make the large power motor to achieve the requirement of resonance waveform current stipulated by the EMC standard by only increasing a small amount of control procedure and with the method of shifting phase and needless of alternating the common motor to achieve the aim of economically employing resources.

The invention provides a high power factor three phase rectification circuit comprising a three phase AC power grid, a filter circuit, a rectifier circuit, and a switch circuit; the three phase AC power grid is used for providing power for a whole three phase controllable rectification circuit, and comprises three live lines; the filter circuit is used for filtering AC current outputted by the three phase AC power grid, and comprises three filter inductors; the rectifier circuit is used for converting AC voltage inputted by the filter circuit to DC voltage, and comprises a diode rectifier bridge, two electrolytic capacitors and two stabilization resistors; the switch circuit is used for compensating harmonic wave current, so the harmonic wave current waveform can approach to a sine waveform, and comprises three bidirectional controllable switches and two reverse-conducting switches. The high power factor three phase rectification circuit can limit the harmonic wave current, and improves net side power factors.

The invention discloses a harmonic current control method of an asymmetric six-phase permanent magnet synchronous motor. The method comprises the steps of S1, carrying out decoupling on the voltage vectors in the six-phase permanent magnet synchronous motor to obtain current variables idq and idqz in a dqz coordinate system; S2, carrying out FCS-MPC control on the current variable idq to obtain aninstruction voltage signal V*dq; S3, enabling the current variable idqz to be subjected to PR regulator control to obtain an instruction voltage signal V*dqz; S4, carrying out dq inverse transformation and dqz inverse transformation on the V*dq and V*dqz to obtain instruction voltage signals V* alpha beta and V*xy under an xy coordinate system respectively; and S5, carrying out spatial vector coupling on the V* alpha beta and V*xy to obtain a coupled instruction voltage signal V*phs and then generating a control signal Dphs to carry out SPWM to be given to an inverter so as to control the motor. According to the control method disclosed by the invention, the minimum harmonic current control is realized, the structure is simple; compared with the classical FCS-MPC, only a proportional resonance regulator needs to be added in the xy subspace without affecting the alpha beta current, that is, the added PR regulator does not influence the original performance of the output torque.

The invention discloses a magnetic suspension rotor harmonic current suppression method based on a multi-order repetitive controller. According to the method, for a magnetic suspension control momentgyroscope, a magnetic suspension rotor dynamic model containing mass imbalance and sensor harmonic waves is established firstly, then signals of the first three periods are processed by adopting a multi-order repetitive controller so as to adjust the current, and effective suppression of the harmonic current under the fixed frequency is realized. The method can achieve the effective inhibition ofthe harmonic current at any fixed rotating speed, and is suitable for the inhibition of the harmonic current of the magnetic suspension rotor with mass imbalance and sensor harmonic waves. By applyingthe repetitive controller, the harmonic current is accurately suppressed, and the notch width at each frequency point is relatively wide, so that the frequency robustness of the control system is improved.

The embodiment of the present invention discloses a method for suppressing the harmonic current of a refrigerator, a frequency conversion plate and a refrigerator refrigerating system, the method comprises: receiving a compressor target frequency transmitted by a main control board of the refrigerator and sending a starting command to the compressor if the target frequency of the compressor is greater than 0; calculating the power of the compressor according to the output voltage and the output current of the frequency conversion plate after the compressor is started; starting a power factor correction circuit if the power of the compressor is greater than or equal to a threshold; according to the input current phase and the voltage phase of the frequency conversion plate, adjusting the input current of the frequency conversion plate according to the power factor correction circuit, so that for the frequency conversion plate, the input current phase matches with the input voltage phaseand the harmonic current is suppressed. By adding the PFC circuit in the frequency conversion plate the modification cost is lower. The PFC circuit is started when the power of the compressor is greater than or equal to the threshold, the input current of the frequency conversion plate is adjusted, the input current phase matches with the input voltage phase, thereby suppressing the harmonic current, reducing standby power and improving the energy efficiency of the whole machine.

The invention discloses an electric network positive and negative reactive power compensation device which is applied to compensate the voltage and the reactive power of an electric network. The electric network positive and negative reactive power compensation device comprises a pressure regulator (2), one or a plurality of capacitors (9) and one or a plurality of reactors (6), wherein the line inlet end of the pressure regulator (2) is connected with a bus (7) by a circuit breaker (1); the capacitor (9) and the reactor (6) are connected with the line outlet end of the pressure regulator by one or a plurality of switches; after being connected with the reactor and the switch (4) connected in front of the reactor in parallel, the capacitor and the switch (3) connected in front of the capacitor are connected to the line outlet end of the pressure regulator (2); and the reactor is connected to the inside of a branch circuit of the capacitor in series. The invention provides a still reactive power compensation device which can supply capacitive compensation and inductive compensation, regulates the reactive power output of the capacitor and the reactor by regulating the output voltage of the pressure regulator, does not switch the capacitor at rated voltage, prevents serious overvoltage and inrush current and can realize finite order fine regulation in a total range from rated capacitive compensation capacity to rated inductive compensation capacity.

The invention discloses a control method for an active power filter based on double-side voltage information. The control method comprises the following steps of: carrying out phase locking on sampled power supply voltage to obtain a sine value of a phase angle and a starting point of power frequency cyclic waves by a digital phase-locked loop; comparing the sampled APF (Active Power Filter) direct-side capacitance voltage with a set value through a subtracter, sampling and storing and averaging according to the period of power supply voltage; carrying out PI (Proportional Integral) computation on an average value of the direct current side capacitance voltage at a starting point of the power frequency cyclic waves and outputting a fundamental wave active component amplitude of a load; multiplying the fundamental wave active component amplitude of the load with the sine value of voltage phase and outputting fundamental wave active current of the load; and subtracting the fundamental wave active current of the load from total current of the load, outputting compensation current required by the load and directly controlling a converter in a hysteresis comparison mode. According to the control method disclosed by the invention, start from a transmission angle of instantaneous active and reactive energy in the system, troublesome processes of detecting the active and reactive components are avoided and the suppression of harmonic current or compensation of reactive power is realized.

The invention discloses an alternating current-direct current (AC-DC) converter which comprises a converter based on a three-phase thyristor, a full-bridge converter based on a simplified insulated gate bipolar transistor (IGBT) and an inductor connected between the converter and the full-bridge converter, wherein in a driving mode, the converter based on the three-phase thyristor works in an AC-DC rectifier mode, and the full-bridge converter based on the simplified IGBT works in a boost chopper circuit mode and controls the inductor to suppress current harmonics of the power supply network so as to increase the power factor; and in a regenerative braking mode, the converter based on the three-phase thyristor feeds the regenerated energy back to the power supply system so as to realize energy recovery. The invention also discloses a frequency converter. By using the scheme, the power factor can be increased, energy recovery can be realized, and the implementation cost is low.