88 results about "Perturbation and observation" patented technology

The present invention focuses on the development of a high-performance solar photovoltaic (PV) energy conversion system. The power circuit of the invention is made of a two-stage circuit, connecting a step-up DC-DC converter and a full-bridge inverter in serial. The present invention uses an adaptive perturbation and observation method to increase tracking speed of maximum power position and at the same time reduces energy loss. In addition, the full-bridge inverter's output has to have the same phase with the utility power in order to achieve unit power factor and increase the system efficiency. The present invention uses voltage type current control full-bridge inverter to achieve the goal of merging into utility grid. The present invention provides an active Sun tracking system, by utilizing the character of changing in open circuit output voltage with Sun radiation strength to follow the Sun, and decreases the system cost and increases system effectiveness.

A maximum power point tracking system, named flash supercapacitor-solar power device, and method for a solar power system, which mainly adds a pulse-power supercapacitor for being operated in a dynamic equilibrium are disclosed. The duty ratio D is changed and the voltage variance of the supercapacitor is observed to determine the next adjusting direction of the duty ratio D of the DC/DC converter. In the present invention, only a voltage value of the supercapacitor is needed to be monitored and no current-detection is needed. The output power of the solar power system can be actually estimated. The maximum power is traced in an oscillatory way. Therefore, the operation process of the perturbation and observation method, which is generally implemented currently, is simplified. By utilizing the steady-state equilibrium of the supercapacitor, only the voltage of the supercapacitor needs to be detected, and there is no need to measure and calculate the voltage and current values. The system is simple and easily accessible, which is a maximum power point tracking system and method with high efficiency for a solar power system.

The invention discloses a wireless charging circuit and a control method thereof. The circuit is characterized in that the magnetic coupling type wireless power transmission technology is adopted. The circuit mainly comprises a DC power supply, a primary side high-frequency inverting unit, a primary side series-compensative unit, a power emitting coil, a power receiving coil, a secondary side series-compensative unit, an uncontrolled rectifying unit and a load and power controller unit. According to the wireless charging circuit and the control method, the primary side current is used as the feedback quantity, the maximum power tracking control method based on the variable step size perturbation and observation mode is adopted to automatically adjust the working frequency of the circuit, thus the circuit can work in a circuit frequency splitting point on real time, and as a result, the stable output of the transmission power can be realized; when the deviation distance of a power transceiving coil is within a certain transmission range, the load end of the wireless power transmission circuit can obtain the maximum stable power and is not influenced by the deviation position on the premise that the primary side and the secondary side do not communicate; the requirements on the real-time communication of the primary side and the secondary side are saved; the control method is simple and reliable; the stability of the transmission power can be effectively improved; the wireless charging circuit like an electric car or a mobile charging circuit and the like with requirement on a certain deviation distance apply.

The invention relates to a compound control method of photovoltaic maximum power point tracking on the condition of partial shadow. The method includes the following steps: (1) obtaining an output voltage and output current data array of a photovoltaic array on the condition of the partial shadow; (2) adopting particle swarm optimization to search an initial maximum power working point according to the voltage and current data array; (3) obtaining a corresponding initial duty ratio according to the initial maximum power working point searched by the particle swarm optimization; (4) adopting a self-adaption perturbation and observation method to carry out variable-step duty ratio disturbance control according to the initial duty ratio, and outputting an obtained final duty ratio control signal to a maximum power point control circuit; and (5) according to the final duty ratio control signal, the maximum power point control circuit controlling the photovoltaic array to work and enabling the photovoltaic array to stably work at the maximum power point. Compared with in the prior art, the compound control method of the photovoltaic maximum power point tracking on the condition of the partial shadow has the advantages of being high in searching accuracy, suitable for the photovoltaic maximum power point tracking on the condition of the partial shadow and the like..

An apparatus for tracking a maximum power point includes a converter unit for converting a first power, outputted from a solar cell module, into a second power and a maximum power point control unit for searching for a maximum power point voltage and an open-circuit voltage corresponding to a temperature and solar radiation of the solar cell module, decreasing voltage of the first power from the open-circuit voltage to the maximum power point voltage in a soft-start manner, and then performing Maximum Power Point Tracking (MPPT) control according to a Perturbation and Observation (P&O) algorithm.

The invention provides a system for achieving dynamic wireless constant power charging and a control method for the system. The system comprises an energy transmitting module, an energy receiving module and a constant power tracking control module, wherein the energy transmitting module is used for converting a primary direct current power supply into high-frequency alternating current electrical energy and transmitting the high-frequency alternating current electrical energy in a high-frequency magnetic field coupling manner; the energy receiving module is used for receiving electrical energy and supplying the electrical energy to a load; the constant power tracking control module is used for obtaining a reference control signal according to charging current collected in real time, and adjusting voltage of a rectifying port into a reference control signal to achieve a constant power tracking control. With direct current output by a DC/DC converter at a secondary side as feedback quantity, direct current voltage of an uncontrollable rectifier terminal is disturbed by a perturbation and observation method-based constant power tracking control method; and a transmission voltage gain from the primary side to the secondary side always works on a voltage gain point corresponding to a transmission power extreme point, so that the condition that the system transmits the electrical energy at constant power is ensured, and the output power is kept stable.

The invention provides a maximum power point tracking method based on efficient adaptive perturbation and observation. By the aid of the maximum power point tracking method, the problem that the step size used in a traditional perturbation and observation method in the photovoltaic-battery maximum power point tracking technology is difficult to balance, completely adaptive perturbation can be realized, and tracking speed, stability precision and universality of a system are high. The maximum power point tracking method with a basic principle includes that computing continuous output power values of a photovoltaic array according to filtered voltage and current signals; generating error signals according to changes among power signals; generating adaptive perturbation voltage values via a PI (proportional plus integral) controller; and finally generating a reference value of voltage of the photovoltaic array according to the basic principle of perturbation and observation. An error signal of an actual value and the reference value of the voltage of the photovoltaic signal is computed, and a duty cycle signal d required by a DC/DC converter is generated by another PI controller, so that on and off time of each power switch tube of a phase-shift full-bridge converter is controlled, power outputted by the photovoltaic array is adjusted, and the maximum power output point of the photovoltaic array can be tracked.

The invention provides a photovoltaic power generation system maximum power tracking method and apparatus considering the factor of haze. The method includes the following steps: a. acquiring photovoltaic cell open-circuit voltage, short-circuit current, and cell temperature, and PM 2.5 concentration in air; b. inputting acquired data into a BP neural network prediction model improved based on a harmony search algorithm to obtain a MPP voltage predicted value; c. adjusting the PWM control signal duty factor of a DC-DC converter through a PI controller to enable the actual work voltage of the photovoltaic cell to reach the MPP voltage predicted value; and d. taking the MPP voltage predicted value as an initial value and tracking the maximum power of the photovoltaic cell at a specified disturbance step by means of a perturbation and observation method. The invention further provides a corresponding tracking device. Through the combination of the perturbation and observation method and the model forecasting method and the full consideration of the influence of haze weather to photovoltaic generation, the MPPT tracking precision can be effectively improved, the power loss of a static state is reduced, and the MPPT tracking speed can be improved.

The invention discloses an analogy control circuit capable of achieving photovoltaic cell maximum power point tracing, and belongs to the technical field of power electronic application. The analogy control circuit comprises an analogy multiplier, two differentiators, two comparators, an XNOR and a D trigger. According to the analogy control circuit, based on a perturbation and observation method, the change rate of output currents of a photovoltaic cell and the change rate of the output power of the photovoltaic cell are compared, the simple and practical analogy control circuit is used, the output currents and voltages of the photovoltaic cell only need to be sampled, charging-discharging of output end capacitance of the photovoltaic cell is controlled based on on/off, the output currents (or voltages) of the photovoltaic cell are made to achieve maximum power point currents (or voltages), and the maximum power point tracing in the real sense is achieved. The analogy control circuit capable of achieving photovoltaic cell maximum power point tracing is applied to a solar photovoltaic power generating system, and has good engineering application value.

The invention discloses a direct power control method for inhibiting voltage fluctuation of a DC-side bus of a photovoltaic grid-connected inverter, and belongs to the technical field of converter control. The method comprises the steps of establishing a photovoltaic power generation system, determining instantaneous active components v<alpha> and i<alpha> and instantaneous reactive components v<beta> and i<beta> of a power grid, realizing the maximum power point tracking of a photovoltaic array by adopting a fixed-step perturbation and observation method, determining the disturbance power Pswith a short wavy line thereon by a disturbance observer through a correction link; respectively taking output signals [nu]<^>P and [nu]<^>Q of two PI controllers as the input of a feedforward decoupling controller to construct a feedforward decoupling model, obtaining voltage control signals e<alpha> and e<beta> by combining the output uP and uQ of the feedforward decoupling system based on voltage v<alpha> and v<beta> of the power grid, and carrying out [alpha][beta]/abc conversion on the voltage control signals e<alpha> and e<beta> to obtain an SPWM control signal e<a, b, c> of the inverter. According to the invention, the feedforward disturbance is introduced into the voltage outer loop, and the zero steady-state error tracking of the DC bus voltage can be ensured by adopting a simpleproportional controller; it does not need to obtain phase information of the power grid voltage and does not need to perform synchronous rotation coordinate transformation, so that the stability problem caused by the use of a phase-looked loop (PLL) is avoided.

The invention discloses a maximum power point tracking method for a photovoltaic power generation system under non-uniform illumination. The method comprises the following steps of: detecting the output voltage U[k] and current I[k] of a photovoltaic array at the current moment, judging whether non-uniform illumination exists in the photovoltaic array through a maximum power point tracker, performing a variable step size perturbation and observation method to obtain the maximum power point if the illumination is uniform, and calculating the first reference voltage V0 if the illumination is non-uniform; obtaining the first local maximum power point by the variable step size perturbation and observation method, and recording corresponding voltage V1 and power P1; obtaining the second local maximum power point by the variable step size perturbation and observation method, and recording corresponding voltage V2 and power P2; by parity of reasoning, obtaining the voltage Vn and Vp, comparing n local maximum power points, extracting the maximum local maximum power point and taking the corresponding voltage as reference voltage Vnf+ output by the maximum power point tracker; and finally, calculating to obtain a duty ratio through a controller according to the Vnf+, and tracking the local maximum power point. The maximum power point tracking method has the advantages that the power loss brought by non-uniform illumination in the photovoltaic array in the system is reduced.

The invention discloses a maximum power tracking device for a mini permanent magnetic direct drive wind power generation system and a control method in the technical field of wind power generation, wherein the maximum power tracking device comprises a fan, an MPPT (maximum power point tracking) controller, a rectifier, n air velocity transducers, a revolution speed transducer, a voltage transducer, a current transducer, a DC-DC (direct current to direct current) converter, a driver module, a first capacitor, a second capacitor and a load; the control method comprises the following steps of acquiring air velocity vectors by utilizing the air velocity transducers arranged at different positions, collecting a large number of air velocity vector-optimal revolution speed practical samples, establishing an air velocity-optimal revolution speed prediction model by utilizing a support vector machine, and carrying out the maximum power tracking by combining the prediction model with a small-step perturbation and observation method. The maximum power tracking device for the mini permanent magnetic direct drive wind power generation system and the control method, disclosed by the invention, have the advantages that the tracking speed is increased, and the power loss of a perturbation process is effectively reduced; after the characteristics of a fan changes, the prediction precision is ensured by repeatedly collecting samples and training a new prediction model.

The invention discloses a method for tracking the maximum power of a high-accuracy single-stage photovoltaic power generation system. According to the method disclosed by the invention, a two-stage maximum power tracking method combining a constant voltage method with a variable step size conductance increment method based on power difference disturbance is proposed, the constant voltage method is utilized to fast track to a position near the maximum power point of a photovoltaic system at a first stage, the constant voltage method is switched into the variable step size conductance increment method based on the power difference perturbation to accurately track the maximum power point of the photovoltaic system at a second stage, therefore the fast tracking of the maximum power point and the high-accuracy operation of the maximum power point are realized. The method disclosed by the invention can be used for effectively solving the problems of oscillation near the maximum power point, erroneous judgment, and the like of the conventional perturbation and observation method and realizing the fast and high-accuracy tracking of the single-stage photovoltaic power generation system on the operation of the maximum power point.

The invention discloses a perturbation and observation method for tracking a maximum power point of a photovoltaic grid-connected generating system, which is characterized in that reference current amplitude value signals of a grid-connected inverter serve as alternative signals of output power of the grid-connected inverter, and a controller is used for perturbing photovoltaic array reference voltage in real time and determining the direction of perturbing photovoltaic array reference voltage for next time according to reference current amplitude value signal change before and after the photovoltaic array reference voltage is perturbed. By means of ring closure of a PI regulator, reference current amplitude value signals of the grid-connected inverter for next time can be also obtained while practical output voltage of a photovoltaic array tracks the reference voltage in real time. Repeatedly, a maximum power point tracking function of the photovoltaic array can be realized by perturbing the voltage, observing the reference current amplitude value signal change and regulating reference voltage of the photovoltaic array and the reference current amplitude value signals of the grid-connected inverter for next time. By the aid of the method, voltage collapse of a direct-current bus and incapability of correctly tracking in weak sunlight are avoided, hardware cost is reduced, and generating power of the photovoltaic array is improved.

The invention relates to an adaptive variable-step MPPT (maximum power point tracking) control method for coping with quick change of illumination intensity. Based on a perturbation and observation method, sampled direct-current voltage and direct current are detected and judged without adding any hardware detection devices by the aid of an existing hardware structure of a photovoltaic grid-connected inverter, large-step perturbation, small-step perturbation and zero-step perturbation (constant-voltage method) are correspondingly selected, so that tracking speed, steady accuracy and tracking efficiency simultaneously meet requirements, the shortcomings of an existing MPPT method are overcome, and energy loss caused by power fluctuation and low tracking efficiency is avoided.

The invention provides a direct current-direct current converting circuit uniform power control method suitable for a photovoltaic micro-grid system. By the adoption of the direct current-direct current converting circuit uniform power control method suitable for the photovoltaic micro-grid system, the MPPT function and the limiting power control function can be achieved, it can be guaranteed that the system stably operates during grid connection and grid disconnection and the output power is optimal, and a certain energy storage and management capacity can be achieved under the condition of grid disconnection. The uniform power control method is based on perturbation and observation. The achievement of a limiting power control method is changed according to the fact whether an energy storage device is full or exceeds a limiting current. In order to improve the rapidness of the limiting power control method, a variable-step-size perturbation and observation method is further introduced, and the steady-state performance and the dynamic performance are considered at the same time. According to the direct current-direct current converting circuit uniform power control method suitable for a photovoltaic micro-grid, the MPPT function and the limiting power control function can be combined organically, implementation is easy, and operation of the photovoltaic micro-grid system can be effectively expanded; in this way, the utilization efficiency of renewable energy power generation is improved easily, and high application value and good popularization prospect are achieved.

The invention provides a photovoltaic array multi-peak maximum power point tracking method. According to the method, a power curve of an array is rapidly sampled based on the characteristics of a photovoltaic cell, power of each peak value point is estimated, the region where a global peak value is located is determined, single-peak MPPT is conducted in the region, and then global multi-peak MPPT is achieved. The method mainly includes the following steps of firstly, changing an output voltage of the array, and rapidly sampling the power curve of the array; secondly, analyzing the peak value condition of the array and estimating the size of peak values according to the characteristic parameters of a cell panel and sampling data, and determining the region where the global peak value is located; thirdly, conducting single-peak MPPT of a variable step size perturbation and observation method in the region; fourthly, repeating the method regularly or repeating the method when the actual power much deflects from the calculated maximum power. By means of the method, only a plurality of points on the power curve of the photovoltaic array are sampled based on the characteristic parameters of the photovoltaic cell panel, estimation values of all peak values can be obtained through simple operation, the region where the global peak value is located is rapidly positioned, and the method has the advantages of being clear in concept, simple in control structure, easy to implement in engineering and the like.

The invention discloses a power distribution network voltage fluctuation out-of-limit inhibition method based on a flexible multi-state switch. The power distribution network voltage fluctuation out-of-limit inhibition method comprises the following steps: firstly, obtaining two intersecting shafts and the values of direct-axis components through static/rotary coordinate transformation by measuring the three-phase alternating current voltage of each port of the flexible multi-state switch, and then obtaining the resultant vector amplitude of the three-phase voltage of each port to obtain the average value of the voltage amplitude of each port as a regulated and control value of voltage; then, applying disturbance on the active power of the flexible multi-state switch, and obtaining the sensitivity of the voltage of each port of the flexible multi-state switch on active power according to a perturbation and observation method; and finally, obtaining an active power command of each portaccording to the regulated and control value of voltage and the sensitivity, and adjusting the active power of each port to reach the purpose of inhibiting voltage fluctuation out-of-limit. Based on the existing working mode of the flexible multi-state switch, the voltage fluctuation out-of-limit inhibition of a power distribution network is realized, and the power distribution network absorptivecapacity of a distribution power supply is promoted.

The present invention discloses a photovoltaic cell MPPT simulation method based on fuzzy logic control. The method comprises design of a fuzzy logic controller and fuzzy logic control simulation; wherein the design of the fuzzy logic controller comprises: determining input/output amount and the structure of the controller, determining the fuzzy subset and the domain of the input/output amount, determining the subordinating degree function of the input/output amount and determining the fuzzy control rule, etc. Through combination of the control idea of the perturbation and observation method and the fuzzy logic control theory, the photovoltaic cell MPPT simulation method based on fuzzy logic control is provided; the simulation model is built to compared with and simulate the perturbation and observation method and the conductance increment method; according to the simulation result, the fuzzy logic control is very suitable for the MPPT control of the photovoltaic system so as to rapidly and accurately lock the MPP range, and the fluctuation is little after the system is stable.

The invention discloses a maximum power tracking method for a vehicle waste heat power generation system. The three-stage maximum power tracking method combines a constant voltage method and a small-step-size hysteresis comparison method; according to the first stage, the constant voltage method is used for rapidly tracking the position nearby the maximum power point of a temperature difference power generation system; according to the second stage, the small-step-size hysteresis comparison method is adopted for accurately tracking the maximum power point of the temperature difference power generation system; according to the third stage, a timer is applied for performing timing skipping, the system collects open-circuit voltage again for tracking the maximum power, and therefore rapid maximum power point tracking and high-precision maximum power point operation are achieved. The problem that oscillation, misjudgment and the like are caused near the maximum power point according to a conventional perturbation and observation method can effectively solved, the tracking speed is increased, the tracking precision is improved, and rapid high-precision maximum power tracking operation of the vehicle waste heat power generation system is achieved.

The invention provides a photovoltaic power supply. The photovoltaic power supply comprises a Boost circuit, a capacitor, a current detection circuit, a voltage detection circuit, a multiplying circuit, a first delay circuit, a second delay circuit, a first comparison circuit, a second comparison circuit, an inclusive-OR logic circuit and a driving circuit. According to the change rule of the output voltage and the output power of a photovoltaic cell, a logic control circuit is formed; on or off control on a power electronic device in a power conversion circuit can be realized; the circuit structure is simple; the tracking speed is rapid; the practicability is high; in a process of tracking the maximum power point, any control algorithm and control strategy is unnecessary; the problems, such as controller design and control parameter adjustment, in the traditional methods, such as a perturbation and observation method and an incremental conductance algorithm, can be avoided; and thus, the photovoltaic power supply is easy to implement.

The invention discloses a photovoltaic MPPT control method based on fuzzy PI two-way linear prediction. The method includes the following steps that first, a power-voltage characteristic curve of a photovoltaic cell is obtained, two-way linear prediction is performed through the tangent line of the characteristic curve to approach the maximum power point, and the approximate maximum power point is obtained through calculation; second, on the basis of the approximate maximum power point, the actual maximum power point is tracked with a perturbation and observation method, and the error e(k) and the error conversion delta e(k) are calculated, wherein delta e(k)= e(k)- e(k-1), the k represents the period, P represents the power, and u represents the voltage; third, the error e(k) and the error conversion delta e(k) serve as input of a fuzzy controller, the Mamdani fuzzy reasoning method is adopted for the fuzzy controller, a fuzzy control rule is established with the target that the output power can fast reach a given value, and maximum power point tracking is achieved. The method effectively solves the problem that the tracking speed and the calculating precision can not be taken into consideration at the same time with a traditional MPPT control method, the maximum power point can be tracked fast and accurately, and the method is simple and practical.

The invention provides a capture method for wave power generation system maximum output active power. The method comprises the steps that the motion state of a wave power generation system is subjected to frequency domain analysis, it is concluded that the output active power of the wave power generation system is related to a two-dimensional variable set [Rg, Kg], and Rg is resistance in electric generator equivalent impedance; Kg is capacitance in the motor equivalent impedance; according to the mathematic relation of the output active power of the wave power generation system and the two-dimensional variable set [Rg, Kg], a relation curve graph is drawn, different disturbance step sizes are set by zone according to the slope of points on the curve in the relation curve graph, alternate disturbance is applied to two dimensions of Rg and Kg on the basis of a variable step size perturbation and observation method to constantly and rapidly seek the maximum output active power operation point of the wave power generation system, and on the condition that no accurate parameters of the wave power generation system are known, equivalent impedance of the wave power generation system is adjusted, and therefore the wave power generation system can capture the maximum output active power all the time.