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Showing papers on "Maximum power point tracking published in 1992"


Patent
Yukio Kandatsu1
03 Jun 1992
TL;DR: In this article, a DC/AC inverter controlling system consisting of an inverter unit for inverting DC (direct current) power derived from the solar cell power source into AC (alternating current) energy to be supplied to an AC power line, and a power variation judging unit for judging whether or not a variation measured during a predetermined time period and occurring in the AC power outputted from the DC or AC inverter units, exceeds a predetermined value, thereby producing a power variance judging signal, while the power variation does not exceed the predetermined value.
Abstract: A DC/AC inverter controlling system controls a DC/AC inverter so as to continuously output maximum AC power thereof, taking account of solar energy generated from a solar cell. The DC/AC inverter controlling system comprises: a DC/AC inverter unit for inverting DC (direct current) power derived from the solar cell power source into AC (alternating current) power to be supplied to an AC power line; a power variation judging unit for judging whether or not a variation measured during a predetermined time period and occurring in the AC power outputted from the DC/AC inverter unit, exceeds a predetermined value, thereby producing a power variation judging signal; and a power controlling unit for controlling the DC/AC inverter unit so as to reduce the power variation to substantially zero in response to the power variation judging signal, while the power variation does not exceed the predetermined value. As a result, the AC power outputted from the DC/AC inverter unit becomes a maximum value thereof.

155 citations


Proceedings ArticleDOI
09 Nov 1992
TL;DR: In this article, a simplified MPPT control strategy based on the positive feedback of a maximum power point tracking (MPPT) converter output current was introduced to reduce the energy cost from renewable energy generators by optimizing the utilization of the renewable energy source.
Abstract: A novel simplified control strategy, based on the positive feedback of a maximum power point tracking (MPPT) converter output current, is introduced. Cost-effective MPPT reduces the energy cost from renewable energy generators by optimizing the utilization of the renewable energy source. MPPT for relative small photovoltaic (PV) systems, with battery back-up, is achieved by maximization of the output current to the battery by employing this simplified positive feedback control strategy. This strategy was tested by using a buck converter topology. Experimental verification of the operation of this controller is included. This controller can be utilized in small (one or two panel) as well as larger installations, so that the total MPPT converter cost may be a fraction of the solar panel cost. >

66 citations


Book
01 Jan 1992
TL;DR: In this paper, the authors describe the ways that ordinary families fail to develop self-esteem and self-acceptance in children, and suggest techniques for adults to do so on their own.
Abstract: Describes the ways that ordinary families fail to develop self-esteem and self-acceptance in children, and suggests techniques for adults to do so on their own.

61 citations


Journal ArticleDOI
TL;DR: In this article, a high-efficient power electronic converter, for converting the output voltage of a solar panel, or wind generator, to the required DC battery bus voltage has been realized.

52 citations


Journal ArticleDOI
TL;DR: In this article, typical strategies for battery charge regulation and load control in stand-alone photovoltaic (PV) systems are presented, along with terminology used by the PV industry for battery chargers.
Abstract: Typical strategies for battery charge regulation and load control in stand-alone photovoltaic (PV) systems are presented. Several charge algorithms (methods of controlling current to the battery) are presented, along with terminology used by the PV industry for battery charge controllers. Information gained from an extensive evaluation of commercially available charge controllers and data collected from tests on PV systems in the field are discussed. An overview of battery performance characteristics needed for the successful design and long-term operation of PV systems is presented with the intent of soliciting feedback on the information presented from the battery industry. >

52 citations


Proceedings ArticleDOI
04 Oct 1992
TL;DR: In this article, a novel means of obtaining sinusoidal, unity power factor input currents in switched mode power supplies using minimum additional components is presented, which is topologically equivalent to a boost converter cascaded by a forward power converter, but is realized using only a single power stage.
Abstract: A novel means of obtaining sinusoidal, unity power factor input currents in switched mode power supplies using minimum additional components is presented. The converter is topologically equivalent to a boost converter cascaded by a forward power converter, but is realized using only a single power stage. A detailed analysis of the operation is presented. A constant frequency current mode control provides excellent transient performance at the output and sinusoidal input currents at the input. Various tradeoffs involved in the design of the converter elements and control parameters are discussed in depth. All the results are backed up by experimental waveforms from a laboratory converter. >

50 citations


Proceedings ArticleDOI
29 Jun 1992
TL;DR: In this article, the concept of modular power conditioning systems for photovoltaic (PV) applications is discussed, with particular reference to the battery as the load, and a MOSFET-based power conditioning unit (PCU) of 1 kW capacity is discussed in detail along with a control algorithm to track the maximum power point.
Abstract: The concept of modular power conditioning systems for photovoltaic (PV) applications is discussed, with particular reference to the battery as the load. A MOSFET-based power conditioning unit (PCU) of 1 kW capacity is discussed in detail along with a control algorithm to track the maximum power point. Maximum power from each PV array is extracted in spite of any mismatch in the array characteristics. One system controller is capable of handling several PCUs, simplifying the design and resulting in a lower cost of the system. It was observed that the maximum power point tracking (MPPT) increases the power output by abut 10% over a day as compared to the direct connection. >

30 citations


Patent
Stephen L. Knupp1
06 May 1992
TL;DR: In this article, the authors proposed a method to allocate a demanded amount of power to a plurality of power output apparatus, each of which has a cost curve associated therewith, such that each of the power output devices supplies a portion of the demanded power, and the total power outputted from the plurality of devices being optimally cost efficient.
Abstract: The method allocates a demanded amount of power to a plurality of power output apparatus, each power output apparatus having a cost curve associated therewith, such that each of the power output apparatus supplies a portion of the demanded power, and the total power outputted from the plurality of power output apparatus being optimally cost efficient. Data is entered for each of the power output apparatus into a controller. Solutions are generated for all possible output power demands using an optimization by parts technique within output power bounds of each of the power output apparatus. The solutions indicate the portion of power each power output apparatus is to supply to provide the total power demanded at the optimal cost efficient. The solutions are stored in tables within a storage unit of the controller. Upon receipt of a demand for power, a search is performed of the solution tables to obtain the amount of power each power output apparatus is to supply to meet the demand. Control signals are then outputted to each of the power output apparatus, the control signals being indicative of the amount of power to be supplied.

29 citations


Proceedings ArticleDOI
18 Oct 1992
TL;DR: In this article, a control scheme for parallel-connected converter systems that will transfer the maximum available power from a nonideal voltage source is presented, which can dynamically regulate the DC-DC converter system to track the peak power point of the source.
Abstract: A control scheme for parallel-connected converter systems that will transfer the maximum available power from a nonideal voltage source is presented. Monitoring the rates of change in both the average input current and the average input power from the source, the proposed control scheme can dynamically regulate the DC-DC converter system to track the peak power point of the source. The amplitude and the frequency of oscillation due to a limit cycle around the system peak power point are analyzed. >

25 citations


Proceedings ArticleDOI
D.B. Snyman1, Johan H. Enslin
09 Nov 1992
TL;DR: A novel maximum power point tracking (MPPT) converter topology, based on the parallel power conversion technique (PPCT), to enhance the energy conversion efficiency in photovoltaic (PV) systems is analyzed.
Abstract: A novel maximum power point tracking (MPPT) converter topology, based on the parallel power conversion technique (PPCT), to enhance the energy conversion efficiency in photovoltaic (PV) systems is analyzed. Extensive experimental verification of the operation of this converter topology, compared to other topologies, is included. Based on these results, the MPPT topologies are evaluated against each other for utilization in PV systems. The PPCT topology has the highest efficiency compared to the other power converters on the same basis. This increased efficiency is experimentally evaluated and analytically described. It is shown experimentally that the PPCT results in a meaningful enhancement of the basic converter efficiency, from 76% to 94% with a 12 V battery and from 85% to 95% with a 36 V battery. >

23 citations


Patent
16 Jul 1992
TL;DR: In this paper, the authors proposed a method to prevent the operating voltage from being largely apart from a maximum power point by dispensing with control of the maximum power pint and keeping an unchanged state if generated power is changed by the change of the solar radiation quantity while judging the change cause of the generated power.
Abstract: PURPOSE:To prevent the operating voltage from being largely apart from a maximum power point by dispensing with control of the maximum power pint and keeping the operating voltage in an unchanged state if generated power is changed by the change of the solar radiation quantity while judging the change cause of the generated power. CONSTITUTION:A measuring device 4 measures the power generated by a solar battery 1 and stores the measured values in a memory device 5. A control circuit 3 decides whether the generated power is changed by the change of the operating voltage or the change of the solar radiation quantity. When the change of the solar radiation quantity is performed, a power converter 2 is instructed to dispense with tracking control of the maximum power point, and the maximum power point tracking control is performed only when the solar radiation is stable. That is, all the measured values of the measurement value W1 set before the change of the operating voltage, the measurement value W2 set after the change of the operating voltage, and the measurement value W3 set when the changed operating voltage before the change is restored are stored and then compared with each other. Then the operating voltage before the change is kept when W1 W2 and W2>W3 are satisfied respectively.

Patent
12 Mar 1992
TL;DR: In this article, a single power converter is used to convert power supplied from an external AC power source to a heating-energy radiator, which then radiates heating energy to the heating chamber.
Abstract: An electric cooking apparatus includes a single power converter section for converting power supplied from an external AC power source. A heating-energy radiator section receives the converted power from the power converter section and radiates heating energy to a heating chamber. A battery is also provided for supplying power to the power converter section such that a sum of the power from the external AC power source and the battery is converted by the power converting section when an instantaneous voltage of the external AC power source is smaller than a predetermined voltage level, which predetermined voltage level is smaller than a maximum instantaneous voltage of the external AC power source.

Patent
18 Nov 1992
TL;DR: In this article, the authors proposed a highly efficient operation device of an inverter which can efficiently operate the inverter, which is operated in parallel making a connection from a DC power supply such as a solar cell and a fuel battery to an AC power supply.
Abstract: PURPOSE:To provide a highly efficient operation device of an inverter which can efficiently operate the inverter which is operated in parallel making a connection from a DC power supply such as a solar cell and a fuel battery to an AC power supply. CONSTITUTION:This device is provided with a circuit detecting input or output current or power of an inverter by connecting a plurality of current-control type inverters to an AC power supply 8 for parallel operation and selects the number of inverters for the highest efficiency by switching the number of inverters and then operate them by judging the output using a level detector 21.

Proceedings ArticleDOI
29 Jun 1992
TL;DR: In this article, the authors describe a control method for a resonant DC-DC converter in a small-scale photovoltaic system linked up with storage batteries, which is suitable for tracking control of storage battery charging.
Abstract: The authors describe a control method for a resonant DC-DC converter in a small-scale photovoltaic system linked up with storage batteries. The converter is suitable for tracking control of storage battery charging. The control method and experimental results are presented. Optimum operation was achieved by the application of the improved control circuit presented. With this circuit, it is possible to implement tracking control for various intensities of solar radiation. >

Patent
02 Oct 1992
TL;DR: In this article, the authors proposed to prevent an erroneous operation of a controller by providing first power source means for supplying a voltage to a starter motor and second power source voltage of the controller.
Abstract: PURPOSE:To prevent an erroneous operation of a controller by providing first power source means for supplying a voltage to a starter motor and second power source means for holding a power source voltage of the controller. CONSTITUTION:A power capacitor 34 is connected as first power source means to a main battery 10 through a DC/DC converter 20. Further, an auxiliary unit battery 22 as second power source means, and EV-ECU 36 and E/G-ECU 38 as controllers are connected to the battery 10 through a DC/DC converter 20. Accordingly, at the time of driving a starter motor 24, driving power of the motor 24 is mainly supplied from the capacitor 34. The power source voltages of the EV-ECU 35 and EGG-ECU 38 is held constantly by the battery 22. Thus, an erroneous operation of the controller can be prevented.

Proceedings ArticleDOI
29 Jun 1992
TL;DR: The performance and dynamic characteristics of a solid-state power factor compensator which simultaneously eliminates line current harmonics and substantially reduce the harmonic content of the line current when the load is nonlinear are presented and analyzed.
Abstract: The performance and dynamic characteristics of a solid-state power factor compensator which simultaneously eliminates line current harmonics are presented and analyzed. Power factor compensation is achieved by controlling the magnitude and the phase angle (delta) of the transistorized PWM inverter output voltage. Fast response times are obtained by adjusting the amplitude of the PWM inverter output voltage through a modulation index control. The principal advantage of this scheme is that it can maintain a near unity mains overall power factor without sensing and computing the associated reactive components. It can also substantially reduce the harmonic content of the line current when the load is nonlinear. A time domain model is derived and used to accurately predict dynamic behavior and stability region, and to adjust system controllers. The transfer function of the power factor compensator is obtained. Experimental results confirm the operation characteristics obtained by computer simulation and analyses. >


Patent
22 Jan 1992
TL;DR: In this article, the maximum power point tracking (MPPT) is carried out by analogue means: measurement (4, 5, 7, 8) of the power (Vi), differentiation (9), and comparison (11) with zero in order to deduce therefrom the correction signal (13).
Abstract: Supply with MPPT device for low-orbit satellite. Regulators (R1, R2, R3) which are controlled by current rather than by voltage are provided. Moreover, Maximum Power Point Tracking, or MPPT, is carried out entirely by analogue means: measurement (4, 5, 7, 8) of the power (Vi), differentiation (9) of the latter, and comparison (11) with zero in order to deduce therefrom the correction signal (13).

Patent
30 Jan 1992
TL;DR: In this paper, a half-bridge inverter and a method for controlling such a welding inverter which has a nominal output power P n and a nominal operating angular frequency ω t, the inverter being comprised of a DC power source (E); of a capacitor configuration comprising at least one capacitor (C n ), the circuit being connected at its first end to one end of the DC power sources (E) and at its other end to a point A; of two switching elements (T 1, T 2 ) connected in series over the DC Power supply (E),
Abstract: The present invention concerns a half-bridge inverter and a method for controlling such a welding inverter which has a nominal output power P n and a nominal operating angular frequency ω t , the inverter being comprised of a DC power source (E); of a capacitor configuration comprising at least one capacitor (C n ), the circuit being connected at its first end to one end of the DC power source (E) and at its other end to a point A; of two switching elements (T 1 , T 2 ) connected in series over the DC power supply (E), the switching elements being capable of controlling the pulse width τ of the current to the welding load, and thus the power to the welding load, whereby τ max determines the nominal power output of the inverter; and of a transformer primary (L p ) connected at its first end to point A and at its second end to the center point of the switching elements (T 1 , T 2 ), and the current switched through the primary has a peak value I i . At output power levels which exceed the critical output power P k , the total capacitance ΣC of the capacitor circuit (C n ) is smaller than the product of the current I i and the pulse width τ divided by the voltage E of the DC power source (ΣC<(I i ×τ)/E), and the resonant angular frequency ω r (=1/√L p τC) determined by the total inductance L p of the transformer primary and the total capacitance of the capacitor configuration (C n ) is essentially lower than the operating angular frequency ω t of the inverter.

Proceedings ArticleDOI
22 Sep 1992
TL;DR: In this article, the authors discuss the power system requirements and propose solutions for power system design on board a low Earth orbit (LEO) microsatellite for communication and mapping purposes.
Abstract: The University of Stellenbosch is currently developing a low Earth orbit (LEO) microsatellite for communication and mapping purposes. Since this will be the first South-African-developed experimental satellite, the project will also be used to gain new technology for future aerospace and satellite applications. The authors discuss the power system requirements and propose solutions for the power system design on board the satellite. They discusss the simulation and analysis of the power system requirements of the orbiting satellite. Power electronic converters to be used will include maximum power point tracking, battery regulation, bus regulation, and distributed power conversion. The specification and designs of key components, i.e., the solar panels, battery, and regulators, are evaluated against the system requirements during a typical flight path. These simulations include all the different modes of operation of the power system in an orbit cycle.

Journal ArticleDOI
TL;DR: It is shown that the DC-AC converter has excellent tolerance for various faults which occur in a PV power system.
Abstract: Discusses transient operation of the orthogonal-core-type DC-AC converter for a grid-connection-type photovoltaic (PV) power system. In particular, they consider the transient operation when the converter is connected to and disconnected from the utility grid on the basis of simulation and experiment. Furthermore, they examine the converter behavior when a line-to-line fault occurs in the utility grid. It is shown that the DC-AC converter has excellent tolerance for various faults which occur in a PV power system. >

Proceedings ArticleDOI
D.B. Snyman1
22 Sep 1992
TL;DR: In this article, the authors proposed a decentralized energy storage in every house, with access restricted to the particular house, to encourage energy management by the individual households in rural areas, by charging remaining batteries at a higher rate when some of the batteries are fully charged.
Abstract: A novel technique for the reduction of the overall system cost of PV (photovoltaic) systems in rural areas is presented. This technique consists of centralized PV generation at a maximum power point voltage of between 90 V and 108 V, power distribution at around 85 V, and decentralized battery storage at 12 V (nominal). Maximum power point tracking (MPPT), single axis solar path tracking (daily), and reflectors are used to maximize the energy from the PV array. Decentralized energy storage in every house, with access restricted to the particular house, encourages energy management by the individual households. Load diversity is exploited by charging remaining batteries at a higher rate when some of the batteries are fully charged. Low distribution losses are obtained by charging the 12 V batteries in series, but access to the energy in the 12 V batteries is restricted to the individual households only. Experimental results are presented, including the power conversion efficiencies of the MPPT and the battery regulator, the energy conversion efficiency of a storage battery, and the increase in ampere hours from a PV panel using a three-stage solar path tracker.

Patent
30 Apr 1992
TL;DR: In this article, the authors proposed a distributed power system which can economically reduce unbalance in a three-phase or single-phase three-wire load by adjusting the output standard of a single-photon inverter based on the value of the current of the load.
Abstract: PURPOSE: To realize a distributed power system which can economically reduce unbalance in a three-phase or single-phase three-wire load. CONSTITUTION: In a distributed power system which is constituted of a dc supply 1, a single-phase inverter 3, current transformers 5, 7, etc., and is connected to a commercial power system 6 and then is connected to a load 8 in a small consumer such as a housing, three sets of single-phase inverter 3 are used when the commercial power system 6 is three-phase and two sets are used when the commercial power system 6 is single-phase three-wire and an output adjuster 9 is installed which supplies power to the load 8 and adjusts the output standard of the single-phase inverter 3 based on a value of the current of the load 8 and compensates for an unbalance between lines. COPYRIGHT: (C)1993,JPO&Japio

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a modified method of Prof. Boehringer's maximum power tracking technique to improve the operation in the region of high frequency, which was used to track the maximum power point of the solar array at the high frequency.
Abstract: Photovoltaic power can be generated even in small size installation. In a residential photovoltaic system the solar cell module array is mounted on the roof. In this case the controller for the maximum power tracking is required to be compact because the space of the control installation is not easily obtainable. For this reason the development of the high frequency operating controller is essential. However the e-i characteristics of the solar array at the frequency have hysteresis. In such frequency region the conventional controller based on no hysteresis can not be responsible for control of the power system. Therefore, it is necessary to develop a now control method to track the maximum power point of the solar array at the high frequency. In this paper the authors proposed a modified method of Prof. Boehringer's maximum power tracking technique to improve the operation in the region of high frequency. The distinguishing characteristic of this method is to be controlled by the estimated values which do not depend on the operating frequency. The experimental result of the power system controlled by the proposed method shows excellent performances.

Proceedings ArticleDOI
29 Jun 1992
Abstract: A resonant-type five-level pulse-width-modulated (PWM) inverter for small-scale photovoltaic systems is presented. The output waveform of this inverter has multiple levels of voltage, achieved by connecting two units of power source in series or parallel. The operation of and experimental results for this inverter are presented. An efficient circuit which uses two inductors with coupling is proposed to attain high efficiency with this inverter. The inverter also exhibits reduced low-order harmonics. >


Proceedings ArticleDOI
17 Feb 1992
TL;DR: A new type of PWM inverter, a resonant type five-level PWM Inverter, is presented, which has smaller harmonic contents and lower switching losses than those of a conventional P WM inverter.
Abstract: ABS TRACT This p a p e r descr ibes a small scaled photovoltaic generation system linked up with storage batteries. A new type of PWM inverter, a resonant type five-level PWM inverter, is presented. The waveform of the output voltage caused by this inverter has smaller harmonic contents and lower switching losses than those of a conventional PWM inverter. A resonant DC link circuit is introduced in order to realize the high efficiency of the system. The operation and experimental r e s u l t s o f t h i s i n v e r t e r are presented.

Proceedings ArticleDOI
22 Sep 1992
TL;DR: In this article, an improved digital method based on FFT (fast Fourier transform) techniques is used for active power measurement of an inverter-fed induction motor in a photovoltaic water pumping system.
Abstract: Active power measurement of an inverter-fed induction motor in a photovoltaic water pumping system is considered. An improved digital method based on FFT (fast Fourier transform) techniques is used. Measurement results show the advantages of this method over currently available power measurement apparatus. This technique is applied at the intermediate AC stage for inverter output power measurement corresponding to the power consumed by the motor. Thus, both motor and power converter behavior can be analyzed from the resulting power estimation according to efficiency or the electromechanical criterion. It is shown that the digital techniques used for the power measurement make it possible to obtain reliable results.

Journal ArticleDOI
TL;DR: In this article, experiments, analyses and reviews of three-phase inverters (frequency-divide type inverters) which combine a phase converter utilizing a frequency-Divide function with a single-phase square-wave inverter are presented.
Abstract: Ferro-resonant type power supplies are highly reliable, and are therefore used as power supplies for electronic devices. Recently a three-phase inverter (called a phase-conversion type inverter), a combination of a single-phase square-wave inverter and a phase converter utilizing the phase conversion function of a ferroresonant circuit, has been proposed. However, the use of a phase converter causes difficulties, in that the output voltages are not balanced and the efficiency remains at about 60%. This paper reports experiments, analyses and reviews three-phase inverters (frequency-divide type inverters) which combine a phase converter utilizing a frequency-divide function with a single-phase square-wave inverter. As a result, the device characteristics were determined, and a high output balance and high system efficiency were achieved.

01 Jan 1992
TL;DR: In this paper, the power conditioning unit (PCU) is built in a modular way and is controlled by a micro controller for maximum power point tracking (MPPT), where power MOSFETs are used as switching elements.
Abstract: This paper deals with some design issues involved in a photovoltaic power conditioning system. The power conditioning unit (PCU) is built in a modular way and is controlled by a micro controller for maximum power point tracking (MPPT). The choice o f the power converter and suitable pv_array configuration are also discussed. Power MOSFETs are used as switching elements. Experimental system of 1kW capacity is also explained, with battery charging as a specific application.