German Journal of Renewable and Sustainable Energy Research, Nov 4, 2013
This paper presents the analysis of a water pumping system from PV solar system using a current-f... more This paper presents the analysis of a water pumping system from PV solar system using a current-fed parallel resonant push-pull inverter, for residential applications in rural areas. The power structure is particularly simple and robust. It works in a ZVS commutation. Its main features are: one power processing stage, simple control strategy, lower harmonic distortion of the load voltage and natural isolation. The principle of operation, design procedure and experimental results are presented. Keywords: PV water-pumping system; push-pull inverter; current-fed parallel resonant inverter; single-phase system.
Several topologies have been researched in search of a structure which not only is able to fulfil... more Several topologies have been researched in search of a structure which not only is able to fulfil the requirements of the power factor and the amount of harmonics injected in a line foreseen in the norms, but which would also show the best ensemble of characteristics. Although being the most frequently employed and studied structure, the boost converter presents some limitations in its application, for it is not a naturally isolated structure and because it only operates as step up voltage. As an alternative to these limitations the Zeta converter operating in discontinuous mode applied to the power factor correction was proposed (D.C. Martins, 1994). The Zeta converter showed itself as very attractive because it operates as step up as well as step down voltage, beside the fact of being a naturally isolated structure and processing power at one single stage. But in applications which imply high power, the operation of a converter in discontinuous mode is not attractive because it results in high RMS values of the currents causing high levels of stress in the semiconductors. Aiming to extend the alternative by use of the Zeta converter in power factor correction to applications in higher powers, and having in mind the main characteristics and advantage of this converter in face of the limitations of the boost converter, this paper presents the study of the Zeta converter operating in continuous conduction mode for power factor correction by using the average current mode control.
The work presented in this paper concerns the analysis and implementation of a feedback algorithm... more The work presented in this paper concerns the analysis and implementation of a feedback algorithm applied to numerical simulation of static converters with closed loop control. The proposed method can be applied either PWM modulation or current-regulated modulation. In both cases the output signal of the converter is compared with a reference signal and the difference between them is used to drive a power static switch. The validity of the proposed algorithm is proved by computer simulation of a Zeta and Sepic converters, both employing the technique of power factor correction.
Construction d'un algorithme de resolution des equations d'etat, concu pour la simulation... more Construction d'un algorithme de resolution des equations d'etat, concu pour la simulation numerique des convertisseurs statiques avec un pas variable adaptatif permettant de tenir compte de la dynamique. Modelisation des transistors bipolaires en regime de commutation
This paper presents the computer simulations in software PSIM of a proposed system of integration... more This paper presents the computer simulations in software PSIM of a proposed system of integration of energy sources in which the TAB converter serves as interface. In TAB converter a transformer serves to magnetically link the converters. Besides the advantage of galvanic isolation, this topology easily affords different levels of voltages on its ports. This can be done by the proper choice of the turns ratio of transformer windings and suitable adjustment. The proposed system has a load, a main source of voltage and an auxiliary power source formed by a photovoltaic panel and a Sepic converter that is used as a transformer DC-DC. The converter is fed into voltage, and applies a method of decoupling loops for control of voltage. The MPPT of the PV panel is made with the method of voltage constant. It's observing a smooth exchange of power between the ports. The current in system has good behavior, even without control. The system presented can be used in UPS and micro-grids.
... Vo(t). (7) Vin( s) - Vref I s - Vref I s - Vo( s) - ZI z2 Where: Riz Z -Ri 1 - '+ Ri... more ... Vo(t). (7) Vin( s) - Vref I s - Vref I s - Vo( s) - ZI z2 Where: Riz Z -Ri 1 - '+ Riz.Ci.s+l Rf.Cf.s+l Cf.s 22 = lsolating Vo(s) in equation (6) , we arrive at: (9) Vref Let us define e(s) = -- Vin(s) . In this way S equation (1 5) takes on the following form ...
The photovoltaic (PV) conversion efficiency is affected by PV cell temperature and solar irradian... more The photovoltaic (PV) conversion efficiency is affected by PV cell temperature and solar irradiance modifications as they originate the vertical and horizontal displacement of the system Maximum Power Point (MPP), respectively. Maximum Power Point Tracking (MPPT) algorithms are responsible for guarantee MPP operation, which can be complex depending on the climatic alterations. However, if the PV cell temperature is kept constant climatic changes will only generate vertical displacement of the MPP. Therefore, in this paper, a cooling system for PV cells is presented and its influence as a facilitator of the MPPT both experimentally and theoretically is studied. The results show that the proposed cooling system allows a steadier PV cell temperature, which leads to a steadier MPP voltage while simultaneously producing thermal energy. Due to the smaller amplitude and a slower variation of the PV system MPP voltage, provided by the cooling system, a simplification of the MPPT is possible. Simpler MPPT algorithms can be use offering a similar efficiency to the more advanced MPPT methods while creating an economically viable cogeneration system.
A simple technique for overcoming the difficulties found in ZVS-QRCs (zero-voltage switching quas... more A simple technique for overcoming the difficulties found in ZVS-QRCs (zero-voltage switching quasi-resonant power converters), such as voltage stress, limited load range, and large switching frequency range is presented. The technique consists of replacing the linear resonant inductor with a nonlinear one, so that the inductance value decreases with increasing load current. The nonlinear resonant inductor is constructed with an
Abstract The analysis of a PV solar energy electronics processing system, operating at the maxim... more Abstract The analysis of a PV solar energy electronics processing system, operating at the maximum power point (MPP) for commercial refrigerator supply applications is presented in this paper. The refrigerator is fed from a battery bench using two electronics processing ...
German Journal of Renewable and Sustainable Energy Research, Nov 4, 2013
This paper presents the analysis of a water pumping system from PV solar system using a current-f... more This paper presents the analysis of a water pumping system from PV solar system using a current-fed parallel resonant push-pull inverter, for residential applications in rural areas. The power structure is particularly simple and robust. It works in a ZVS commutation. Its main features are: one power processing stage, simple control strategy, lower harmonic distortion of the load voltage and natural isolation. The principle of operation, design procedure and experimental results are presented. Keywords: PV water-pumping system; push-pull inverter; current-fed parallel resonant inverter; single-phase system.
Several topologies have been researched in search of a structure which not only is able to fulfil... more Several topologies have been researched in search of a structure which not only is able to fulfil the requirements of the power factor and the amount of harmonics injected in a line foreseen in the norms, but which would also show the best ensemble of characteristics. Although being the most frequently employed and studied structure, the boost converter presents some limitations in its application, for it is not a naturally isolated structure and because it only operates as step up voltage. As an alternative to these limitations the Zeta converter operating in discontinuous mode applied to the power factor correction was proposed (D.C. Martins, 1994). The Zeta converter showed itself as very attractive because it operates as step up as well as step down voltage, beside the fact of being a naturally isolated structure and processing power at one single stage. But in applications which imply high power, the operation of a converter in discontinuous mode is not attractive because it results in high RMS values of the currents causing high levels of stress in the semiconductors. Aiming to extend the alternative by use of the Zeta converter in power factor correction to applications in higher powers, and having in mind the main characteristics and advantage of this converter in face of the limitations of the boost converter, this paper presents the study of the Zeta converter operating in continuous conduction mode for power factor correction by using the average current mode control.
The work presented in this paper concerns the analysis and implementation of a feedback algorithm... more The work presented in this paper concerns the analysis and implementation of a feedback algorithm applied to numerical simulation of static converters with closed loop control. The proposed method can be applied either PWM modulation or current-regulated modulation. In both cases the output signal of the converter is compared with a reference signal and the difference between them is used to drive a power static switch. The validity of the proposed algorithm is proved by computer simulation of a Zeta and Sepic converters, both employing the technique of power factor correction.
Construction d'un algorithme de resolution des equations d'etat, concu pour la simulation... more Construction d'un algorithme de resolution des equations d'etat, concu pour la simulation numerique des convertisseurs statiques avec un pas variable adaptatif permettant de tenir compte de la dynamique. Modelisation des transistors bipolaires en regime de commutation
This paper presents the computer simulations in software PSIM of a proposed system of integration... more This paper presents the computer simulations in software PSIM of a proposed system of integration of energy sources in which the TAB converter serves as interface. In TAB converter a transformer serves to magnetically link the converters. Besides the advantage of galvanic isolation, this topology easily affords different levels of voltages on its ports. This can be done by the proper choice of the turns ratio of transformer windings and suitable adjustment. The proposed system has a load, a main source of voltage and an auxiliary power source formed by a photovoltaic panel and a Sepic converter that is used as a transformer DC-DC. The converter is fed into voltage, and applies a method of decoupling loops for control of voltage. The MPPT of the PV panel is made with the method of voltage constant. It's observing a smooth exchange of power between the ports. The current in system has good behavior, even without control. The system presented can be used in UPS and micro-grids.
... Vo(t). (7) Vin( s) - Vref I s - Vref I s - Vo( s) - ZI z2 Where: Riz Z -Ri 1 - '+ Ri... more ... Vo(t). (7) Vin( s) - Vref I s - Vref I s - Vo( s) - ZI z2 Where: Riz Z -Ri 1 - '+ Riz.Ci.s+l Rf.Cf.s+l Cf.s 22 = lsolating Vo(s) in equation (6) , we arrive at: (9) Vref Let us define e(s) = -- Vin(s) . In this way S equation (1 5) takes on the following form ...
The photovoltaic (PV) conversion efficiency is affected by PV cell temperature and solar irradian... more The photovoltaic (PV) conversion efficiency is affected by PV cell temperature and solar irradiance modifications as they originate the vertical and horizontal displacement of the system Maximum Power Point (MPP), respectively. Maximum Power Point Tracking (MPPT) algorithms are responsible for guarantee MPP operation, which can be complex depending on the climatic alterations. However, if the PV cell temperature is kept constant climatic changes will only generate vertical displacement of the MPP. Therefore, in this paper, a cooling system for PV cells is presented and its influence as a facilitator of the MPPT both experimentally and theoretically is studied. The results show that the proposed cooling system allows a steadier PV cell temperature, which leads to a steadier MPP voltage while simultaneously producing thermal energy. Due to the smaller amplitude and a slower variation of the PV system MPP voltage, provided by the cooling system, a simplification of the MPPT is possible. Simpler MPPT algorithms can be use offering a similar efficiency to the more advanced MPPT methods while creating an economically viable cogeneration system.
A simple technique for overcoming the difficulties found in ZVS-QRCs (zero-voltage switching quas... more A simple technique for overcoming the difficulties found in ZVS-QRCs (zero-voltage switching quasi-resonant power converters), such as voltage stress, limited load range, and large switching frequency range is presented. The technique consists of replacing the linear resonant inductor with a nonlinear one, so that the inductance value decreases with increasing load current. The nonlinear resonant inductor is constructed with an
Abstract The analysis of a PV solar energy electronics processing system, operating at the maxim... more Abstract The analysis of a PV solar energy electronics processing system, operating at the maximum power point (MPP) for commercial refrigerator supply applications is presented in this paper. The refrigerator is fed from a battery bench using two electronics processing ...
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