Description:[001] The present invention relates to the field of power electronics and renewable energy systems, and more particularly to a solar photovoltaic and battery integrated power conversion system configured to generate, regulate, and supply electrical power for motor drive applications. The invention specifically pertains to a high voltage gain DC–DC converter employing switched-capacitor topology with ripple minimization, integrated with a battery energy storage system and intelligent control architecture for driving a brushless DC motor and associated direct current loads under varying environmental and operational conditions.
BACKGROUND OF THE INVENTION
[002] The global transition toward sustainable and environmentally friendly energy systems has accelerated the adoption of renewable energy technologies, particularly solar photovoltaic systems. Solar energy offers a clean and abundant source of power; however, its intermittent nature due to variations in irradiance and weather conditions poses significant challenges in delivering a stable and reliable power output for practical applications.
[003] In recent years, brushless DC motors have gained widespread acceptance in industrial automation, electric vehicles, and domestic appliances due to their high efficiency, compact structure, low maintenance requirements, and superior performance characteristics. Despite these advantages, the operation of BLDC motors requires a stable and regulated DC supply, which is difficult to achieve directly from fluctuating renewable energy sources such as solar photovoltaic systems.
[004] Conventional DC–DC converters, including boost converters, have been extensively used for stepping up low input voltages to levels suitable for motor drives and other applications. However, these converters suffer from inherent limitations such as restricted voltage gain at moderate duty cycles, high switching stress on semiconductor devices, and significant input current ripple, which adversely affect efficiency and reliability.
[005] To overcome these limitations, various high-gain converter topologies such as coupled inductor-based converters and interleaved converters have been proposed. While these approaches can achieve higher voltage gains, they introduce additional complexities such as increased component count, leakage inductance, electromagnetic interference, and lack of common ground, thereby limiting their practical applicability in compact and cost-effective systems.
[006] Switched-capacitor based DC–DC converters have emerged as a promising alternative due to their ability to achieve high voltage gain without relying on magnetic coupling. These converters utilize capacitor-diode networks to boost voltage levels efficiently; however, existing designs often face challenges such as increased switching losses, higher component stress, and insufficient reduction of input current ripple.
[007] Another critical aspect in renewable energy systems is the integration of energy storage solutions to ensure uninterrupted power supply. Battery energy storage systems are commonly employed to store excess energy during peak generation and supply power during low generation periods. However, efficient management of charging and discharging cycles through bidirectional converters remains a complex task, particularly when maintaining a stable DC bus voltage.
[008] Furthermore, existing systems often lack effective control strategies to manage dynamic variations in both source and load conditions. Inadequate control mechanisms can lead to poor voltage regulation, increased ripple, slow dynamic response, and reduced overall system stability, especially in applications involving motor drives with varying speed and torque requirements.
[009] In addition, many prior solutions do not adequately address the issue of source current ripple, which can lead to reduced lifespan of photovoltaic modules and decreased system efficiency. High ripple content also contributes to thermal stress and electromagnetic interference, thereby impacting the performance of the entire system.
[010] Therefore, there exists a need for an improved power conversion system that can provide high voltage gain, reduced ripple, efficient energy management, and stable operation while integrating solar photovoltaic energy with battery storage for reliable BLDC motor drive applications.
[011] The present invention addresses the aforementioned limitations by providing a solar-battery integrated system incorporating a high gain switched-capacitor DC–DC converter with ripple minimization and an advanced control strategy, thereby ensuring efficient, stable, and reliable operation under varying environmental and load conditions.
OBJECTS OF THE INVENTION
[012] The primary objective of the present invention is to provide a solar photovoltaic and battery integrated power conversion system capable of delivering a stable and regulated high voltage output suitable for driving a brushless DC motor and associated direct current loads.
[013] Another objective of the present invention is to provide a high voltage gain DC–DC converter employing a switched-capacitor topology configured to achieve enhanced voltage boosting capability while operating at moderate duty cycles.
[014] A further objective of the present invention is to minimize input current ripple and reduce voltage stress on switching devices, thereby improving overall efficiency and reliability of the power conversion system.
[015] Another objective of the present invention is to integrate a battery energy storage system with a bidirectional converter configured to enable efficient charging and discharging operations based on power availability and load demand.
[016] Yet another objective of the present invention is to provide an intelligent control strategy comprising a dual-loop control architecture for maintaining stable DC bus voltage and ensuring fast dynamic response under varying operating conditions.
[017] A further objective of the present invention is to ensure uninterrupted power supply to the BLDC motor and connected loads during fluctuations or absence of solar irradiance.
[018] Another objective of the present invention is to enhance system stability, reduce switching losses, and improve overall performance of renewable energy-based motor drive systems.
[019] Still another objective of the present invention is to provide a compact, efficient, and scalable power conversion architecture suitable for applications in electric drives, microgrids, and distributed energy systems.
SUMMARY OF THE INVENTION
[020] The present invention provides a solar photovoltaic and battery integrated power conversion system configured to deliver a stable and high voltage DC output for driving a brushless DC motor and associated direct current loads. The system is designed to overcome limitations associated with conventional renewable energy-based power systems, particularly in terms of voltage gain, ripple reduction, and energy management.
[021] In accordance with the invention, a solar photovoltaic source is employed as a primary energy generator, wherein the output of the photovoltaic source is regulated using a maximum power point tracking mechanism based on an Incremental Conductance algorithm. The tracking mechanism dynamically adjusts operating parameters to extract maximum available power under varying irradiance and environmental conditions.
[022] The regulated output from the photovoltaic source is supplied to a high voltage gain DC–DC converter employing a switched-capacitor topology. The converter comprises an input inductor, switching elements, and a network of capacitors and diodes configured in a voltage-lift arrangement to achieve enhanced voltage gain while minimizing switching stress and input current ripple.
[023] The converter operates by storing energy in the inductor during an active switching interval and transferring the stored energy to the capacitor network during a non-conducting interval, wherein the capacitors are arranged to cumulatively increase the output voltage. The inclusion of the inductor at the input stage reduces ripple content and stabilizes current drawn from the photovoltaic source.
[024] The system further comprises a battery energy storage unit coupled to the DC bus through a bidirectional DC–DC converter configured to operate in both buck and boost modes. During conditions of excess solar power generation, the converter operates in a charging mode to store energy in the battery, whereas during low irradiance or increased load demand, the converter operates in a discharging mode to supply power from the battery to the DC bus.
[025] A dual-loop control strategy is implemented to ensure stable operation of the system, wherein an outer voltage control loop maintains the DC bus voltage at a predetermined reference level, and an inner current control loop regulates the current flow within the system to achieve fast dynamic response and improved stability.
[026] The stabilized DC output is supplied to a brushless DC motor through an inverter, wherein the motor is controlled based on rotor position feedback to ensure proper commutation and efficient torque generation. The system is further configured to support additional DC loads connected to the same DC bus.
[027] The integrated configuration of solar photovoltaic source, high gain DC–DC converter, battery energy storage system, and intelligent control architecture ensures continuous power supply, improved voltage regulation, reduced ripple characteristics, and enhanced overall efficiency.
[028] The invention thereby provides a reliable and efficient solution for renewable energy-based motor drive applications, particularly in scenarios involving fluctuating power availability and dynamic load conditions.
BRIEF DESCRIPTION OF THE DRAWINGS
[029] The accompanying drawings are included to provide a further understanding of the present invention and are incorporated herein to illustrate exemplary embodiments of the invention. The drawings, together with the description, serve to explain the principles, configuration, and operation of the disclosed solar-battery integrated power conversion system, and are not intended to limit the scope of the invention in any manner.
[030] Figure 1 illustrates the overall system configuration of the solar photovoltaic and battery integrated power conversion system for driving a brushless DC motor and supplying associated direct current loads.
[031] Figure 2 represents the equivalent electrical model of the solar photovoltaic module depicting its operational characteristics.
[032] Figure 3 illustrates the configuration of the high voltage gain switched-capacitor DC–DC boost converter employed in the system.
[033] Figure 4 depicts the flow chart of the Incremental Conductance maximum power point tracking algorithm used for extracting maximum power from the photovoltaic source.
[034] Figure 5 illustrates the configuration of the bidirectional buck-boost converter connected to the battery energy storage system.
[035] Figure 6 represents the control architecture for energy management of the battery energy storage system.
[036] Figure 7 illustrates the configuration of the brushless DC motor drive including inverter and control arrangement.
[037] Figure 8 depicts the speed control architecture of the brushless DC motor employing a control strategy.
[038] Figure 9 illustrates simulation results demonstrating dynamic performance of the system under varying irradiance and motor speed conditions.
DETAILED DESCRIPTION OF THE INVENTION
[039] The present invention provides a comprehensive solar photovoltaic and battery integrated power conversion system configured to supply a stable and high voltage DC output for driving a brushless DC motor and associated DC loads. The invention integrates advanced power electronic converter topology with intelligent control mechanisms to ensure efficient energy utilization, reduced ripple, and enhanced system stability under dynamic operating conditions.
System Overview
[040] The system comprises a solar photovoltaic module acting as the primary energy source, a maximum power point tracking controller configured to extract optimal power, a high voltage gain switched-capacitor DC–DC converter for voltage boosting, a battery energy storage system connected through a bidirectional converter, and a brushless DC motor drive supplied through an inverter. The components are interconnected through a regulated DC bus, which serves as the central energy distribution node.
[041] The system is designed to operate under varying solar irradiance conditions while maintaining a constant DC bus voltage. The integration of the battery energy storage system ensures uninterrupted power supply during periods of low or zero solar generation.
Solar Photovoltaic Configuration
[042] The solar photovoltaic module generates direct current electricity based on incident solar irradiance and temperature conditions. The output voltage of the photovoltaic module typically ranges from low voltage levels, making it necessary to employ a voltage boosting mechanism for practical applications.
[043] The photovoltaic module is modeled as a nonlinear source characterized by photogenerated current, diode current, and resistive losses. The output current of the photovoltaic system is dependent on parameters including temperature, irradiance, and internal resistances.
[044] The photovoltaic output is continuously monitored and controlled using a maximum power point tracking mechanism to ensure that maximum available energy is extracted under all operating conditions.
Maximum Power Point Tracking Control
[045] The system employs an Incremental Conductance-based maximum power point tracking algorithm, which determines the optimal operating point by evaluating the relationship between incremental conductance and instantaneous conductance of the photovoltaic output.
[046] The algorithm dynamically adjusts the duty cycle of the DC–DC converter to maintain operation at the maximum power point. This approach ensures accurate and fast tracking even under rapidly changing environmental conditions, thereby improving overall system efficiency.
High Voltage Gain Switched-Capacitor DC–DC Converter
[047] The photovoltaic output is supplied to a high voltage gain DC–DC converter employing a switched-capacitor topology. The converter comprises an input inductor, multiple capacitors, diodes, and switching elements configured to achieve a voltage-lift mechanism.
[048] During operation, when the switching elements are in an active state, energy from the photovoltaic source is stored in the input inductor while capacitors are charged through diode paths. When the switching elements transition to a non-conducting state, the stored energy in the inductor is transferred to the capacitor network and subsequently to the load.
[049] The capacitors are arranged in a cascaded configuration such that their voltages are added in series, thereby achieving a high voltage gain. This arrangement enables the system to convert low input voltage from the photovoltaic source into a significantly higher output voltage suitable for motor drive applications.
[050] The presence of the input inductor plays a critical role in reducing input current ripple, thereby improving the lifespan of the photovoltaic source and enhancing overall system efficiency.
[051] The converter operates under continuous conduction mode and discontinuous conduction mode depending on load and operating conditions, ensuring flexibility and robustness in performance.
[052] The voltage gain characteristics of the converter demonstrate a quadratic relationship with respect to duty cycle, enabling high output voltage at moderate switching conditions.
Table 1: Key Features of High Gain Converter
Parameter Description
Voltage Gain High (Quadratic boost capability)
Input Ripple Reduced due to inductor filtering
Switching Stress Lower compared to conventional converters
Efficiency Improved through optimized topology
Ground Reference Common ground maintained
Battery Energy Storage System and Bidirectional Converter
[053] The system incorporates a battery energy storage unit to ensure continuous power supply. The battery is connected to the DC bus through a bidirectional DC–DC converter capable of operating in both buck and boost modes.
[054] During periods of high solar irradiance, excess energy generated by the photovoltaic module is directed to the battery for storage. In this mode, the converter operates as a buck converter, reducing the DC bus voltage to a suitable level for battery charging.
[055] During low irradiance or increased load demand, the battery supplies energy to the system. In this case, the converter operates as a boost converter, increasing the battery voltage to maintain a stable DC bus voltage.
[056] The bidirectional converter ensures smooth energy transition between charging and discharging modes, thereby maintaining system stability and reliability.
Control Strategy and Energy Management
[057] The invention employs a dual-loop control strategy comprising an outer voltage control loop and an inner current control loop. The outer loop maintains the DC bus voltage at a desired reference level by generating a reference current signal.
[058] The inner current loop regulates the actual current flow by comparing it with the reference current and adjusting the duty cycle of the switching devices accordingly.
[059] This hierarchical control architecture ensures fast dynamic response, accurate voltage regulation, and improved system stability under varying load and source conditions.
[060] The control system also manages energy flow between the photovoltaic source, battery storage, and load, ensuring optimal utilization of available energy resources.
BLDC Motor Drive System
[061] The regulated DC output is supplied to a brushless DC motor through an inverter. The motor operation is based on electronic commutation using rotor position feedback obtained through sensors.
[062] The inverter switches are controlled in a sequence to generate a rotating magnetic field in the stator, which interacts with the rotor magnets to produce torque.
[063] The motor exhibits trapezoidal back electromotive force characteristics, and the control system ensures proper synchronization between voltage supply and rotor position.
[064] The speed of the motor is controlled using a proportional-integral controller, which adjusts the current supplied to the motor based on the difference between reference speed and actual speed.
Mechanical and Electrical Dynamics of Motor
[065] The electrical behavior of the motor is governed by phase voltage equations incorporating resistance, inductance, and back electromotive force components.
[066] The mechanical dynamics are governed by torque balance equations, wherein electromagnetic torque drives the rotor against load torque and frictional forces.
[067] The control system ensures that the motor achieves desired speed and torque characteristics with minimal overshoot and steady-state error.
System Operation Under Dynamic Conditions
[068] The system is capable of operating under varying solar irradiance conditions. During high irradiance, the photovoltaic source supplies power to both the load and battery storage.
[069] As irradiance decreases, the battery compensates for the reduced power generation, ensuring continuous operation of the motor and connected loads.
[070] In the absence of solar power, the battery fully supports the system, maintaining stable operation without interruption.
[071] The system also supports dynamic speed variation of the motor, with the control strategy ensuring smooth transition between different speed levels.
Advantages of the Invention
[072] The present invention provides several advantages including high voltage gain with reduced component stress, minimized input current ripple, efficient energy management, improved voltage regulation, and enhanced system reliability.
[073] The integration of solar photovoltaic energy with battery storage and advanced control mechanisms enables continuous and stable operation suitable for renewable energy-driven motor applications.
[074] The invention is scalable and can be adapted for various applications including electric vehicles, microgrids, and distributed energy systems, thereby offering a versatile and efficient solution for modern energy requirements.
[075] The present invention provides an integrated and efficient solution for renewable energy-based power conversion by combining a solar photovoltaic source, a high voltage gain switched-capacitor DC–DC converter, and a battery energy storage system for driving a brushless DC motor. The system effectively addresses the limitations of conventional converters by achieving high voltage gain at moderate operating conditions while minimizing input current ripple and reducing stress on switching devices.
[076] The implementation of an Incremental Conductance-based maximum power point tracking mechanism ensures optimal energy extraction from the photovoltaic source under varying environmental conditions. The integration of a bidirectional DC–DC converter with the battery storage system enables seamless energy management, ensuring uninterrupted power supply during fluctuations or absence of solar irradiance.
[077] The dual-loop control strategy employed in the system enhances voltage regulation and dynamic performance by maintaining a stable DC bus voltage and ensuring accurate current control. The coordinated operation of the converter, energy storage system, and motor drive results in improved efficiency, reliability, and operational stability.
[078] The invention demonstrates significant improvements in power quality, reduced ripple characteristics, and enhanced system responsiveness under dynamic load and irradiance conditions. The system is particularly suitable for applications requiring reliable and continuous power supply, including electric drive systems, renewable energy-based microgrids, and standalone power systems.
[079] In future implementations, the system may be further enhanced by incorporating advanced control techniques such as artificial intelligence-based predictive control, adaptive control strategies, or machine learning algorithms for improved energy management and fault detection.
[080] Additionally, the integration of Internet of Things-enabled monitoring systems may allow real-time performance tracking, remote diagnostics, and optimization of system parameters, thereby improving operational efficiency and maintenance.
[081] The converter topology may also be extended to multi-input and multi-output configurations to support hybrid renewable energy systems involving additional sources such as wind or fuel cells.
[082] Furthermore, advancements in semiconductor technologies, including wide bandgap devices, may be utilized to further reduce losses, improve switching performance, and enhance overall system efficiency.
[083] Thus, the present invention provides a robust, scalable, and future-ready platform for renewable energy-driven power conversion systems, addressing current challenges while offering significant potential for further technological advancements.
, Claims:1. A solar-battery integrated power conversion system comprising a solar photovoltaic source, a maximum power point tracking controller, a high voltage gain DC–DC converter, a battery energy storage system, and a brushless DC motor drive, wherein the system is configured to generate, regulate, and supply electrical power to a DC bus for driving the brushless DC motor and associated loads.
2. The system as claimed in claim 1, wherein the maximum power point tracking controller is configured based on an Incremental Conductance algorithm to dynamically extract maximum power from the solar photovoltaic source under varying irradiance conditions.
3. The system as claimed in claim 1, wherein the high voltage gain DC–DC converter comprises a switched-capacitor topology including at least one input inductor, a plurality of capacitors, diodes, and switching elements arranged to achieve a voltage-lift configuration for enhanced voltage gain.
4. The system as claimed in claim 3, wherein the input inductor is configured to reduce input current ripple and stabilize current drawn from the solar photovoltaic source.
5. The system as claimed in claim 1, wherein the battery energy storage system is connected to the DC bus through a bidirectional DC–DC converter configured to operate in a charging mode and a discharging mode.
6. The system as claimed in claim 5, wherein the bidirectional DC–DC converter operates in a buck mode during charging of the battery and in a boost mode during discharging to maintain a stable DC bus voltage.
7. The system as claimed in claim 1, wherein the system further comprises a dual-loop control architecture including an outer voltage control loop and an inner current control loop for regulating DC bus voltage and system current.
8. The system as claimed in claim 1, wherein the brushless DC motor drive comprises an inverter configured to supply controlled voltage to the motor based on rotor position feedback for electronic commutation.
9. The system as claimed in claim 1, wherein the high voltage gain DC–DC converter is configured to reduce switching device stress and improve overall system efficiency.
10. The system as claimed in claim 1, wherein the system is configured to provide uninterrupted power supply to the brushless DC motor and associated loads during variations or absence of solar irradiance.