162 results about "Maximum power principle" patented technology

The invention relates to a conditioning circuit that measures operating points of a power supply to deduce therefrom the current-voltage characteristic thereof and to determine directly the voltage corresponding to its maximum power point, without using any kind of tracking algorithm that causes the operating point of the power unit to oscillate about the maximum power point. The maximum power point voltage VMPP is supplied to a controller which regulates a power cell by slaving it to the input voltage until the output voltage of the supply is equal to the maximum power point voltage VMPP. The invention also relates to a solar generator and an associated conditioning method. One particular application is to high-power satellites.

A power system employs an outer voltage feedback loop and an inner current feedback loop to control a power converter, such as a DC to AC inverter for transferring electrical power between a power source, for example a photovoltaic array, and a load, for example a power grid. The outer loop accommodates variations in the output of the power source, for example accommodating anomalies in IV characteristics such as IV droop characteristic associated with photovoltaic cells. The outer loop may employ a first control regime or a second control regime, for example, dependent on whether a DC bus voltage or power is smaller than a value corresponding to measurement resolution or expected noise.

A detection voltage, which is obtained by dividing the voltage of a fuel cell 1 by resistors, is compared with a first reference voltage Vref 1 by a differential amplifier. The differential voltage is input to a control section. The control section performs PWM control for the circuit section according to the difference. The first reference voltage Vref 1 is set according to the dividing ratio of the resistors, based on the output voltage when the fuel cell generates power at the maximum power point. To determine the output voltage for maximum power generation, a characteristic curve representing a current-voltage characteristic is approximated by an approximating line within a range excluding an area in which the output voltage changes abruptly when the output current is nearly zero, and an extrapolated voltage is obtained on the extension line of the approximating line at an output current of zero. Fifty percent of the extrapolated voltage is then determined as the output voltage when the fuel cell generates power at the maximum power point. Thus, a fuel cell control system that identifies a highly precise output voltage for power generation at a maximum power point and controls power so that the maximum power point is not exceeded could be provided.

A tracking and control method for the hybridded maximum power point of the photovoltaic pumping system. It contains: a, the check and choice logo, it will turn to the step b if it is ture, or it will turn to the step d. b, the output frequency of the inverter will be adjusted the running of the multiple criteria. C, the choice logo will become untrue and the reference voltage Verf=V (n), and the real running time of the normal voltage method, tCV, will be reset, and turn to the step a, or turn to the step a. d, the output frequency of the inverter will be adjusted by the running of the normal voltage method. e, To add a control cycle into the running time of the normal voltage method, tvc, the choice logo will be true if the tvc >= TVC and turn to the step a, or it will turn directly to the step a. it adjust the output frequency by the alternative running of multiple criteria and normal voltage, it can adjust the output frequency in time and control the DC voltage effectively and assure the stable running of the system, the system owns rapid and dynamic tracking characteristics, and a good stable characteristics by taking advantage of this method .

Characters of the invention are that first, microprocessor obtains information of voltage and current of light-volt array; using algorithm for tracking maximum power in order to determine operating point of light-volt array at next moment; through A / D convertor, the information is converted to reference point Vref. After proportional integral PI adjusts difference value between Vref and sampled actual voltage of light-volt array, PWM control chip generates PWM wave with certain duty ratio to control DC-DC convertor. The method can implement coordinational operation of two branches and multiple branches in plug and play mode. Voltage control mode insensitive to maximum power point is adopted in the invention. Tracking effect is raised by method maximum power point instead of method of current tracking. Being in use for power supply for multiple DC loads, the system is applicable to independent light-volt system as well as to networked light-volt system.

The special point is the twin closed loop method for controlling rotary speed and power mutual independently. The control process includes 3 steps: during the original state, executes the power signal feedback control against the fan according to the original max power curve; during the smaller change of wind speed, executes mountain climbing method for controlling optimal power; via the rotary speed disturbance, obtains the max output power under the recent wind speed and the corresponding generator rotary speed. Then according to the original max power curve and the new added data points, obtains modified max power curve. During the larger change of wind speed, executes the power signal feedback control according to the mortified new max power curve. This method adapts the rapid change of the wind speed and is independent from the functions of the wind field and the fan. It can restrain the system disturb near the max power point effectively.

The invention provides a segmentation self-adapting hill climbing method and a system thereof applied for tracing maximum power of a photovoltaic cell. The method comprises: finding the zone of the current power by partitioning the output power of the photovoltaic cell and comparing power difference of two adjacent moments with a set value; then, adjusting duty cycle to measure the power of the next moment until the maximum power point is found. The system of the invention comprises a photovoltaic cell, a DC / DC converter and a plumbic acid storage battery which are connected by circuits in sequence, wherein, a circuit between the DC / DC converter and the plumbic acid storage battery is provided with a voltage detecting module and a current detecting module, the output ends of the voltage detecting module and the current detecting module are respectively connected with a microprocessor, and the output end of the microprocessor is connected with the DC / DC converter via an isolation / driving circuit. The invention quickens the tracing speed of the maximum power point, improves the anti-interference performance of the system, quickens the self-optimizing process of the maximum power point of the system and decreases the oscillation of the system at the maximum power point.

A photovoltaic power generation controller, in which minute power change is detected even with a low-resolution AD converter, thereby being capable of performing maximum power point tracking control with high accuracy, is provided. In the photovoltaic power generation controller of the invention, a control circuit 44 shifts switches 41 to respective output A sides of a voltage detector 8 and a current detector 9; gives a low-frequency ripple component to an operating voltage of a solar cell 1 while increasing modulation factor D by predetermined variation width d, to start maximum power point search from an open circuit voltage side; confirms a maximum power point passage when: an operating point oscillates in the vicinity of the maximum power point; and a power value, which is output by a power detector 43, after update of the modulation factor becomes smaller than a power value before update of the modulation factor; and switches the switches 41 to respective output sides of amplifiers 23 and 24 to continue the maximum power point tracking control.

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.

An energy harvesting system includes: an energy harvesting unit for converting energy from a natural energy source into an electrical power signal; a power point tracking unit including a current tracing module capable of detecting a current of the electrical power signal, and a boundary control module; a microcontroller including a voltage detecting module capable of detecting a voltage of the electrical power signal, and a computing module for determining a maximum power point with reference to the voltage and the current of the electrical power signal, the boundary control module generating a switch control voltage signal with reference to the maximum power point; a storage unit capable of storing energy; and a pulse frequency modulation regulator for converting the electrical power signal into an intermediate signal with reference to the switch control voltage signal for subsequent storage of energy of the intermediate signal in the storage unit.

The invention discloses a variable step size disturbance maximum power point tracking method based on power forecasting. The control method combines a power forecasting method and a variable step size method, leads the voltage value of the theoretical maximum power point of a photovoltaic cell at the current time into a modulating pulse generation process to perform maximum power tracking of the photovoltaic cell through dual-functions of the two methods. By means of the control method, the problem of erroneous judgment and tracking failure when the external environment changes remarkably can be solved, the contradiction existing between the maximum power tracking speed and accuracy can be effectively solved, the maximum power point can be tracked fast, and the theoretical maximum power point voltage can be ensured when the actual working pressure changes along with the environment factors.

The invention relates to a compound control method for the fast and accurate tracking control of the maximum power of a photovoltaic power generation system The photovoltaic power generation system samples the output voltage upv, the current ipv and the working temperature T of the current time of a photovoltaic battery array in real time; photovoltaic output power Ppv (k) is calculated on line and compared with the power Ppv (k-1) of previous time; and if power deviation is larger than a set error range e, a controller fast regulates the output voltage upv by adopting a constant voltage improvement control method till the output power deviation is smaller than the set error range e and then carries out the further accurate tracking control of the maximum power by adopting an admittance incremental method till power error is approximately equal to zero, therefore the purpose of the fast tracking control is achieved. The compound control method can be applied to a photovoltaic power generation MPPT (Maximum Power Point Tracking) control system controlled by adopting an MCU (Microprogrammed Control Unit) or DSP (Digital Signal Processor) chip and has the characteristics of fast response and accurate control.

A method of operating a cascaded multilevel inverter of photovoltaic system to transfer electrical power from a plurality of photovoltaic cells onto an electrical power distribution grid. Power switches in the inverter are operated in a manner effective to combine a block voltage output from each selected photovoltaic blocks series-wise to output an inverter voltage substantially equal to the grid voltage. A selected photovoltaic block may be pulse width modulated to incrementally adjust a current or voltage output by the system. The photovoltaic blocks selected to contribute to the current or voltage output by the system are selected based on a desire to operate solar panels formed by the photovoltaic cells at a maximum power point (MPP) of each solar panel in a photovoltaic block. Shuffling of which blocks are selected may occur at any time during synthesizing a sinusoidal output signal.

The invention discloses a control method for tracking maximum power point of photovoltaic grid-connected generation, which comprises the steps of: taking the iteration initial values of duty cycle D, with Dm equal to 0.2 and Dn equal to 0.9; computing an iteration variable Dy of a maximum power point from an upper line and an iteration variable Dx of a maximum power point from a lower line; computing maximum power Py of Dy according to the iteration variable Dy of the maximum power point from the upper line and detected voltage Uy and Iy thereof; computing maximum power Px of Dx according to the iteration variable Dx of the maximum power point from the lower line and detected voltage Ux and Ix thereof; and computing the maximum duty cycle Dmax by using a golden section method. The controlmethod can realize the computation of the maximum power point and is particularly applicable to the effective tracking of the maximum power point when solar power photovoltaic equipment is started orrestarted.

The invention relates to a solar charging system, a device and a method for tracking a maximum power point thereof. In the method, first-side regulation comprises: performing first change on the output voltage of a current solar battery array and carrying out second-side regulation if the power after the first change is judged to be lower than that before the first change; or setting current dutycycle as the duty cycle of a maximum power point and repeating first-side regulation if the power after the first change is judged to be not lower than that before the first change; and the second-side regulation comprises: performing second change on the output voltage of the current solar battery array and carrying out the first-side regulation if the power after the second change is judged to be lower than that before the second change; or setting the current duty cycle as the duty cycle of the maximum power point and repeating second-side regulation if the power after the second change isjudged to be not lower than that before the second change. The technical scheme of the invention has good steady-state performance and dynamic performance of tracking the maximum power point.

The present invention relates to power supplies, and more particularly, to a power supply having a maximum power point tracking function that controls power switching so that a detected power value is within a reference range having a maximum power point in a predetermined current-voltage curve. A power supply having a maximum power point tracking function according to an aspect of the invention includes: a converter section switching input power and converting the switched input power into predetermined DC power; and a maximum power point tracking section detecting a power value determined according to a switching operation of the converter section among power values included in a predetermined power-voltage curve, and controlling the switching operation of the converter section so that the detected power value is located within a predetermined reference range having a maximum power value among the power values included in the power-voltage curve.

A power converter includes a plurality of converters which are connected in parallel to a DC power supply in which an operating point is changed in accordance with an output current or an output voltage. The plurality of converters include maximum power point tracking units for performing maximum power point tracking calculations of the DC power supply. Results of the maximum power point tracking calculations of the plurality of converters are unified between the plurality of converters and the plurality of converters are controlled based on the unified calculation result.

The invention relates to a method for tracing a maximum power point of a photovoltaic miniature grid-connected inverter. When the output power of a photovoltaic cell is high, the traditional continuous operating mode and a maximum power point tracing method are adopted; and when the output power of the photovoltaic cell is low, intermittent operating mode is adopted, namely operation is continuously performed for a plurality of periods with set power, then operation is stopped for a while to store energy to a capacitor, and simultaneously maximum power point tracing is performed with voltage change rate in the energy storage period, so as to ensure that the photovoltaic cell is operated at maximum power point voltage. The method can effectively solve the problems that the efficiency of a traditional inverter is low when the illumination intensity is low, grid-connected current harmonic wave is large, and the like.

The invention discloses a maximum power point tracking controller for a three-phase photovoltaic power generation system. The controller mainly comprises a BOOST type DC / DC converting circuit, a three-phase inversion circuit, a control circuit and a power circuit. The technical scheme includes that a variable-structure fuzzy control method is applied to MPPT (maximum power point tracking) of photovoltaic power generation so that tracking precision can be improved, and the method can effectively realize maximum power point tracking when illumination and temperature vary. By means of variable-structure fuzzy control, different fuzzy sub-controllers are designed according to different working conditions, the discourse domain range, control rules, parameters and the like of the fuzzy sub-controllers are different, the fuzzy sub-controllers form a variable-structure fuzzy controller, and accordingly one fuzzy sub-controller constantly enables the system to achieve the optimal control quality in system running.

Controller apparatus with MPPT tracking for controlling an electric power generation system comprising two identical sub-sections of a photovoltaic field, connected to two respective identical switching power converters, the two converters being controlled by two respective periodic controlling signals and the outputs of the two converters being connected in parallel. The controller apparatus comprises a first and a second current sensor for detecting the output currents of the two converters, a subtractor capable to receive the two current detection signals and to generate a difference signal, an amplifier capable to amplify the difference signal by a constant gain k, and a low-pass filter capable to filter the amplified difference signal, a proportional-integral controller for controlling the filtered amplified difference signal.

The invention discloses a photovoltaic array maximum power point sliding mode tracking control method and system. The maximum power point tracking control method for obtaining a switch control signal according to the output voltage and current of a photovoltaic array comprises the steps of conducting moving average filtering pretreatment on voltage and current signals to reduce the influence of sampling measurement interference on maximum power point tracking control precision and increase maximum power point tracking speed, calculating the value of a sliding mode function S2 based on incomplete partial differential, and conducting hysteresis on the switch control signal and obtaining the switch control signal u of 0 or 1 according to the relation between the value of S2 and a set value delta. According to the system, an incomplete partial differential-based sliding mode surface function calculating program and a hysteresis processing program are stored in a single-chip microcomputer, the equivalent load of a DC-DC conversion circuit is adjusted and controlled to be matched with the internal resistance of the photovoltaic array, the maximum power of the photovoltaic array is tracked quickly and precisely, the structure is simple, cost is low, and implementation is easy.

The invention discloses a photovoltaic power generation system maximum power tracking method based on model identification. The method comprises the steps that firstly, parameter identification is conducted on a photovoltaic array reference mathematic model by adopting measurement information of a practical photovoltaic power generation system, and an identification model consistent with the practical object is obtained; secondly, a BP neural network is constructed, a series of output voltage and output current test data of the model under different illumination intensities and photovoltaic cell panel temperatures is generated by adopting the identification model, information such as output voltage and output power corresponding to the illumination intensities, the photovoltaic cell panel temperatures and the maximum power points is extracted to be used for training the BP neural network, and parameters of the BP neural network are obtained; finally, the trained BP neural network is used for maximum power tracking of the photovoltaic power generation system on line, and therefore the real-time property and the high efficiency of photovoltaic power generation system maximum power tracking are greatly improved. According to the method, the principle is easily implemented on line, and the flexibility is good.

The invention relates to a non-active disturbance maximum power tracking technology in a photovoltaic grid-connected inverting system, which achieves rapid and disturbance -free photovoltaic array maximum power tracking control according to natural fluctuation of the output power of a photovoltaic array. A working voltage of the photovoltaic array is sampled in a carrier cycle, and the current output power is calculated; a corresponding bus voltage value of the maximum power is searched in a voltage pulsation cycle, the voltage value is taken as a voltage instruction of the next cycle, and the working voltage of the photovoltaic array moves towards a maximum power point; a peak point of the array power variation is positioned in the midpoint of voltage pulse when the working voltage of the system moves to the maximum power point, and the bus working voltage is stabilized according to a maximum power tracking control strategy. The method can not generate the disturbance influence on a grid, has rapider maximum power tracking speed, and is unnecessary to select and set any parameter and suitable for the maximum power tracking control of the single-phase or three-phase photovoltaic grid-connected inverting system.

The invention discloses a two-level type single-phase grid-connected photovoltaic power generation control method aimed at a grid-connected photovoltaic power generation inverter circuit formed by a BOOST converter, a single-phase inverter circuit and a filter. The BOOST converter has two work modes which are a work mode of a BOOST non-work zone and a work mode of a BOOST work zone. The single-phase inverter circuit achieves the function that high-power-factor harmonic current is injected into a power grid through maximum power point tracing outer-ring control and inverter output current inner-ring control. According to the two-level type single-phase grid-connected photovoltaic power generation control method, the BOOST converter does not work for a part of time within a half power grid power frequency circle, so that switching consumption is avoided, and the power of the whole system is further improved.

The invention discloses a photovoltaic power generation system control method for tracking through maximum power point spinning reserve capacity in the technical field of power electronic control. The method comprises the following steps: acquiring photovoltaic cell performance parameters, and converting a photovoltaic cell circuit into an equivalent circuit; determining an initial discriminant relation between output power and output voltage under the condition of tracking the maximum power point of the photovoltaic cell according to the condition that a photovoltaic array output characteristic curve is a single peak curve; changing the power tracking point according to the selection standard of the spinning reserve capacity of the system; simulating mechanical inertia of a synchronous generator, frequency modulator and excitation controller characteristics and a double closed loop control by taking inductive current as inner loop feedback by adopting a VSG power controller according to the relation between the external environment and the photovoltaic array output characteristic curve, and determining the PV-VSG inertia and damping parameters. The maximum power point of the power generation load of a real-time synchronous tracking system at the spinning reserve capacity and the real-time tracking function in a transient stable state can be realized.

Approximately one-half of the loss of delivered power from a solar panel having photovoltaic (PV) cells connected in series to form sub-panels due to shading is recovered at low hardware cost by connecting sub-panels in series and providing maximum power point tracking control in common for the series connected sub-panels such that the respective sub-panels produce equal voltages even in the presence of shading of a portion of one or more sub-panels. By doing so, the input voltage of respective power converters which control the voltage at which each sub-panel is operated can be placed close to the maximum power point of each sub-panel regardless of shading and maximum total power harvested even though the respective sub-panels are not operated at optimum voltages.

The invention relates to a modeling method of a mathematical model for silicon solar cell engineering, which is used for modeling according to the characteristic of large similarity of an I-V characteristic curve of a silicon solar cell and a particle-throwing motion locus curve. In the coordinate system of the particle-throwing motion locus curve, the coordinate system is divided into different gravitational fields by two demarcation points at a maximum-power point voltage position and a voltage position lower than the maximum power point, and then deducing and modeling are carried out according to the principle of kinematics. The invention not only can still meet the requirement of engineering precision well; through adjusting the position of the demarcation point in the voltage position lower than the maximum power point, the model of the invention can be close to actual measurement data in a zone nearby the maximum-power point voltage position well so as to be beneficial to the realization of a maximum power tracking algorithm; and the invention can also greatly improve the response speed of control units in controllers along with the changes of external environments comprising illumination, temperature and the like. When the model is calculated and controlled by adopting controllers comprising a single-chip machine or a DSP (Digital Signal Processor) and the like in engineering practice, the operating time of the model is greatly shortened.

The invention discloses a global maximum power point tracking method for a photovoltaic array. The global maximum power point tracking method for the photovoltaic array comprises the following steps: firstly, dispersing and arranging optical sensors in a photovoltaic array, setting the mounting position of an image collection device, conveying the image and irradiance measurement data synchronous with the image to a photovoltaic power generation system control center via a communication network, analyzing and processing a photovoltaic array operation image by the photovoltaic power generation system control center, distinguishing whether a local shadow exists, and distinguishing the distribution range of the local shadow; then, distinguishing the irradiance data of each position in the photovoltaic array by combining with the irradiance data synchronously measured by the optical sensors; and finally, obtaining the output power-voltage characteristic of the photovoltaic array under the current illumination condition by computer simulation analysis, finding voltage corresponding to the current maximum power point, resetting the reference voltage of MPPT (maximum power point tracking) if the deviation of the voltage and the practical operation voltage exceeds a threshold value, and then dynamically tracking the maximum power point with the traditional MPPT method. According to the global maximum power point tracking method for the photovoltaic array, which is disclosed by the invention, the MPPT accuracy of the photovoltaic array can be obviously improved, extra large-margin power oscillation can be prevented from being generated in the global maximum power point tracking process, and high-performance global maximum power point tracking can be realized.

The invention discloses a maximum power point tracking method based on disturbance observation. The method comprises the steps of firstly, sampling a photovoltaic array voltage, a grid voltage and a grid-connected current signal; then, establishing a dynamic model of a single-stage photovoltaic grid-connected generation system; finally, carrying out maximum power point tracking on the single-stage photovoltaic grid-connected generation system. According to the method, only the photovoltaic array voltage is detected, and a grid-connected reference current amplitude signal Iref is taken as an equivalent signal of output power of a grid-connected inverter, so that the influence on a maximum power point tracking algorithm caused by sampling quantization errors is lowered effectively, and the problems of the traditional disturbance observation methods that in the single-stage photovoltaic grid-connected generation system, the stability of the control strategy is poor and the bus voltage collapses or the output power oscillates are solved.