FIELD OF INVENTION:
The present invention relates to a solar charge controller with multiple arrays. More particularly, the present invention relates to a robust system for efficiently controlling the power output of multiple solar cell array string.
RELATED ART:
Solar cells, whether singly or connected in an array,"have been utilized to supply power in a wide variety of applications. Those applications, for which solar power may be utilized, encompass virtually any device or system which utilizes electric power and range from terrestrial uses in solar powered vehicles and hot water heaters to extraterrestrial uses in spacecraft. Because of the increasing importance and employment of solar generated power, it is necessary to make the most cost effective and efficient utilization of the power generated by a solar array.
Another known system controls a large number of solar array strings grouped together as one. Since each individual solar array string has its power output maximizing voltage determined by different factors, the best peak power point for the group of solar array strings is necessarily less than the peak power outputs of the individual strings when each string is operated at its own output maximizing voltage.
US patent no 5,923,100 describes a system for controlling power supplied by a solar array panel. The system includes a power stage for directing the solar array to discharge an appropriate amount of current, a signal conditioner for receiving and conditioning voltage and current signals from the solar array and determining the signs of the time derivatives of solar array voltage and power, a processor for evaluating the signs of the time derivatives of solar array power voltage and for directing operation of either a battery current control mode or a peak power tracking mode and a high gain amplifier for directing an appropriate voltage to the power stage according to the operating mode. The invention relates to single solar array power system for controlling power output from a solar array to at least a battery and a load.
US patent no 5,327,071 describes a method and an apparatus for efficiently controlling the power output of a solar cell array string or a plurality of solar cell array strings to achieve a maximum amount of output power from the strings under varying conditions of use. Maximum power output from a solar array string is achieved through control of a pulse width modulated DC/DC buck converter which transfers power from a solar array to a load or battery bus. The invention does not provide any protection of conditions such as high heat sink temperature and high surge current protection that may lead to failure of semiconductor devices.
US publication no 20080106921 describes an apparatus and a method of control for converting DC (direct current) power from a solar photovoltaic source to AC (alternating
current) power. DC-to-AC power converter topology and a control method are used. This combination of topology and control are very well suited for photovoltaic micro-inverter applications. The invention relates to an electrical power converter used with a solar photovoltaic source to convert the solar photovoltaic power to AC lines of an electricity utility.
US publication no 20060017327 describes a power and control architecture employing circuitry that sequentially regulate power flows from independent solar-array sources or a mixture of power sources providing power to a common load. The application uses DC-DC buck converter and control architecture to regulate power flow from multiple solar or other power sources.
US publication no 20080111517 discloses a charge controller that includes an input interface that receives input DC electrical signals. A converter section converts the input DC electrical signals to output DC electrical signals^ Control means is operable coupled to the converter section. This application describes the charge controller for a single PV array.
US publication no 20050139258 is directed to a solar cell array control device, which comprises a plurality of solar cell modules, a bidirectional DC converter, at least a voltage sensor and a control unit. The invention does not provide any protection of conditions such as high heat sink temperature and high surge current protection that may lead to failure of semiconductor devices.
US patent no 5,635,816 is related to an automatic photovoltaic controller which provides a fixed frequency, pulse width modulated charging current to charge and regulate a battery wherein the duty cycle of the charging current being controlled by the difference between the sensed battery voltage and a desired regulated voltage. This invention discloses battery charging control methods.
US patent no 6,678,176 and 6,351,400 are about solar power conditioner which converts DC electrical power provided by solar panels (or otherwise) to AC power and uses this to supplement main AC electrical power generated by a power utility (or otherwise) when required. Both the DC power and the main AC power are digitalized by analog to digital (A/D) converters and continuously monitored by a central processor (CPU). The invention deals with the conversion of PV power to AC power.
US patent no 5,270,636 describes a regulating circuit which controls current flow from a photovoltaic power source to a storage battery so as to improve the conversion of solar energy to electric energy. Two transistors are switched on and off at high frequency to regulate the average current flow to the battery. The invention describes a system using a single PV array control.
US patent no 6,204,645 describes a controller for a solar electric generator that permits the generator to produce power substantially at its maximum capacity which also provides efficient charging at three charging stages; i.e., bulk charging, acceptance
charging and float charging. The invention describes a system using a single PV array control.
US patent no 7,319,313 describes an apparatus and method of control for converting DC (direct current) power from a solar photovoltaic source to AC (alternating current) power. DC-to-AC power converter topology and a control method are used which are well suited for photovoltaic micro inverter applications. This patent describes a system using a single PV array control.
US patent no 5,659,465 describes an electrical power conversion system that supplies the maximum available output power from a power source such as a solar array to a plurality of loads such as rechargeable batteries. The output power of the solar array peaks at an optimum current is less than the maximum available output current. This patent describes a system using a single PV array control.
US patent no 7,372,709 is about an apparatus for conditioning power generated by an energy source. The apparatus includes an inverter for converting a DC input voltage from the energy source to a square wave AC output voltage and a converter for converting the AC output voltage from the inverter to a sine wave AC output voltage.
US patent no 7,042,195 describes a photovoltaic power generation system control method that controls a photovoltaic output setting value to be an appropriate value by following up a variation in the solar irradiation. The method includes a genetic algorithm process of employing the photovoltaic output setting value as a gene and the output power as an evaluation value thereof;
US patent no 5,703,468 refers to a charge control apparatus and method for charging of
an electrical energy storage device, such as a rechargeable storage battery, by an
electrical energy source, such as a photovoltaic panel. The invention provides multiple
charge set point selection means. The electrical connection of one or more set point
control terminations to the three electrical potential contacts storage device "+", no
contact (NC), or common "-", produces a specific and predefined charge set point
condition, including charge termination and resumption voltage thresholds, from a
plurality of charge set point possibilities. This patent describes a system using a single
PV array control.
US publication no 20070024257 describes a control circuit for a switching DC/DC converter. The module includes a control circuit and a photovoltaic generator system comprising a plurality of such modules, each controlling a respective photovoltaic generator. This patent describes a system using a DC/DC converter single PV array control.
US publication no 20070044837 discloses a solar cell regulator in a nano-satellite. The regulator includes a pulse width modulated DC-DC boost converter and a peak power tracking controller. The controller controls the pulse width modulation operation of the converter for sensing solar cell currents and voltages along a power characteristic curve
of the solar cell for peak power tracking. This patent relates to the field of power system for nanosatellites and picosatelites. More particularly, it relates to solar cell regulator in ■ solar array power distribution system for small satellites.
Publication no JP2007330057 is about a charge controller for effectively controlling a peak of power supplied from a system power supply and distributing power generation output. This patent describes a system using a single PV array control.
Publication no CN101001025 is directed to a charging and discharging control device for solar lighting equipments, which is mainly composed of solar panels, a storage battery and lighting equipment. A loop switch is installed on the power-loop between the storage battery and the lighting equipment. This patent describes a system using a single PV array control.
Publication no JP60256825 describes a controller which attains the stable supply of power to a system without reducing the lifetime of a storage battery. It also decreases the power loss by using a power detector, a charge/discharge controller, a power limit control circuit and an upper/ lower limit setter. This patent describes a system using a single PV array control.
Publication no JP2095142 describes a charge controller for solar light generating system. A switch controller detects the terminal voltage of the battery and a charging current to control to average the opening and closing numbers of the relay switches Ryl-Ry4 connected to the cell groups PV1-PV4. This patent describes a system using a single PV array control.
Publication no JP4208035 describes a power controller for solar cell. A solar cell array is split into N parallel sub arrays 1-4 which are then connected with individual PWM control switching power converters 9-12 having outputs connected with a power supply bus connected in parallel with a battery and a load.
The invention does not provide any protection of conditions such as high heat sink temperature and high surge current protection that may lead to failure of semiconductor devices.
Publication no CN 1070290 is about multifunctional controller for solar electric generating equipment. The controller is composed of photovoltaic silicon array, automatic charge regulator circuit, automatic distribution circuit, automatic power supply controller circuit, voltage-stabilizing circuit, DC output and protecting circuit, alarm circuit, lagging battery treating and emergency power supply, inversion circuit, two sets of battery, casing, panel & rear cover. It does not provide protection against the wrong configuration of the system connection.
Publication no CN1797892 describes tracker and control method for maximum power of light-volt electric-power production by solar energy. At first, microprocessor obtains information of voltage and current of light-volt array by using algorithm for tracking
maximum power in order to determine operating point of light-volt array at next moment. It does not provide protection against the wrong configuration of the system connection.
Publication no JP 4208035 relates to suppress noise and to obtain a highly reliable power controller by splitting a solar cell array, connecting each of thus split array with a PWM control switching power stage or an ON/OFF switch and performing charge current control. A solar cell array is split into N parallel sub arrays 1-4 which are then connected, respectively, with individual PWM control switching power converters 9-12 having outputs connected with a power supply bus 5 connected in parallel with a battery 6 and a load 7. N PWM switching power converters 9-12 are then switched sequentially according to the charging current control range for the split battery 6 where the ON/OFF duty at the switching power converting stage is varied within 0%-100% within the control range at each stage.; According to the constitution, switching loss is reduced at the power stage and in the switch and noise is suppressed because the switching current is lower than a current generated from a single solar cell array. It does not provide protection against the wrong configuration of the system connection.
Publication no CN1988320 This invention relates to a control method for storage cells used in photovoltaic merging system including solar systems from the first path to n path, in which, each path system includes a photovoltaic array, the output of which is connected with a charge circuit, the output of which is connected with a storage cell, a sample circuit is set to be connected to a load, the CPU process unit controls the charge circuits from 1 to n, a voltage current double closed loop is applied to carry out parallel control with PRI, when the voltage or current of the cell reaches to the threshold, solar energy input of certain paths is cut off/closed one by one, and when the voltage or current of the cell reaches to the maximum or minimum threshold, all of them are cut off/closed. It does not provide protection against the wrong configuration of the system connection.
Through A/D converter, 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 and PWM control chip generates PWM wave with certain duty ratio to
control DC-DC converter. v
Publication no JP6315231 is about a charge controller and control method for battery and photovoltaic power generation system. Charging operation is started when the terminal voltage of a battery is lower than VL and when the terminal voltage rises to VH and the charging operation is sustained for a predetermined time before the charging operation is stopped. This patent relates to a simple solar battery charger and does not mention any protections incorporated in the system. It only utilizes one PV array for charging and does not provide multiple array control.
Publication no JP62154121 describes a charging device high in working efficiency by using a sun tracking device to obtain the maximum voltage from a solar voltage for charging in case the terminal voltage of an accumulator is set at a low level. This patent describes a system using a single PV array control.
Publication no KR20030084085 describes a controller of a power control unit for solar photovoltatic power generation that includes a charging portion, an output portion, a sensing portion and a control portion. The control portion receives the measured current value and the measured voltage value of the sensing portion in order to control the

charging portion and the output portion. This patent describes a system using a single PV array control.
Now, reference may be made to an article by Alternative Energy Store. The article describes Pulse Width Modulated (PWM) charge controllers. They tend to be less expensive than MPPT (Maximum Power Point Tracking) charge controllers and also less efficient than the MPPT type. It uses a single PV array in the system.
Reference may be made to an article by Xantrex. The article explains Solar Charge Controller PWM, series constant voltage 3-stages charging and full amps to bulk voltage. It tapers amps for absorption and then to lower float voltage. DC diversion regulators divert extra power not needed to charge the battery and make hot water or space heat. In this mode, controller is connected between battery and electric dump load. It uses a single PV array in the system.'
Further, reference may be made to an article by Renewable Energy World, 2008. The article explains Apollo Solar T80 Turbo Charger which is a premium MPPT charge controller designed especially for larger power systems. A single unit can process up to 5300 watts of PV power. Patent-pending MPPT algorithm starts early and locks onto the peak power during rapidly changing insolation and temperature. The T80 includes a built-in energy monitor using TriMetric. Technology from Bogart Engineering and remote communications options includes monitoring via PC's, the internet and a full-featured wireless remote data display. Installers like the integrated energy monitor, the easy automatic set-up, the optimized MPPT energy harvest, the wireless remote display and especially the 80 Amps at higher temperatures. It uses a single PV array in the system.
Reference may be made to the product by Steca. The article explains charge controllers using pulse width modulation (PWM) for optimum battery charging and includes automatic battery gassing function. It uses a single PV array in the system.
Reference may be made to the product by Morning Star, Photo Voltaic Bulletin Volume 2003, Issue 9, Page 4. The article explains TriStar controller which is a three-function controller that provides solar battery charging, load control or diversion regulation._It uses a single PV array in the system.
Reference may be made to the product by Outback, 2007. The article explains Outback MX60 60 Amp charge controller. The outback MX60 allows to use a higher output voltage PV array with a lower battery voltage - such as charging a 24 VDC battery with a 48 VDC PV array. It uses a single PV array in the system
Reference may be made to the product by Solar Equipment. The article explains Sunsei 10a charge controller. Intelligent PWM charge control ensures batteries reach max capacity LED indicator instantly displays charging status screw terminal connections for
quick and easy installation auto-reset circuit breaker for reverse polarity and surge protection. It uses a single PV array in the system.
Reference can also be made to the article by RV Power Products Encinitas, USA. The article explains Solar Boost™ 3048 which is a 30 amp 24/48 volt Maximum Power Point Tracking (MPPT) photovoltaic (PV) charge controller. Through the use of patented MPPT technology, Solar Boost 3048 can increase charge current up to 30% or more.
Solar Boost 3048's sophisticated three stage charge control system can be configured to optimize charge parameters to precise battery requirements based on battery electrolyte type, battery size in amp-hours and battery temperature. It uses a single PV array in the system.
Reference is made to the article by ETA Engineering, Inc., Mesa, AZ, January 17, 2008. The article explains patented maximum power point tracking (MPPT) technology that allows Solar Boost 2000E to increase charge current up to 30% or more compared to the conventional charge controllers. The Splar Boost 2000E provides a precision multi-stage pulse width modulation (PWM) charge control system to ensure the battery is properly and fully charged, resulting in enhanced battery performance with less battery maintenance. There is a built in LCD digital display which monitors solar charge performance.Jt uses a single PV array in the system.
Reference is also made to the article by I.H. Altas, and A.M. Sharaf, Renewable Energy Volume 33, Issue 3, Pages 388-399, March 2008. The article explains a novel enhanced, cost-effective MPP detector (MPPD) and dynamic MPP tracking (MPPT) controller for a hybrid mix of electric loads.
Reference is also made to an article by Morning Star, Junuary 07, 2008. The article explains a PV Charge controller which connects between PV modules and the battery to prevent overcharge and night time loss. The controller has connection for battery voltage sensing wires for better accuracy, 9 volt minimum operation voltage, 125 volt maximum solar voltage, 20mA self-consumption, 7.5 mA meter self-consumption, protection for reverse polarity, short-circuit, over current, high temperature, transient voltage surges, 3 LEDs for status, faults, alarms, push button for manual reset, start/stop battery equalization or load disconnects, RS-232 computer connector for custom settings such as 36 volt, data logging and remote monitoring and control, conformal coated circuit board for humidity and insect protection. It uses a single PV array in the system.
Thus, most of the conventional system describes system using a single PV array control. DC-DC buck converter and control architecture are used in some systems to regulate power flow from single or multiple solar or other power sources. Some of the invention does not provide any protection of conditions such as high heat sink temperature and high surge current protection that may lead to failure of semiconductor devices or conditions such as wrong configuration of the system connections etc.
With all the above discussed restrictions or limitations, it is essential to have improved solar cell array controller. The present invention provides a solar charge controller system and method, which provides a robust design and modular structure to connect and control multiple PV arrays to charge the connected battery bank. A system which provides protection against various conditions mentioned above and also provides remote monitoring and control facility.
OBJECT OF THE INVENTION
The primary object of the present invention is to provide solar charge controller with capability of controlling multiple array of PV panels.
Another object of the present invention is to control the multiple arrays of PV panels simultaneously.
Yet another object of the invention is to charge batteries from the PV panels.
Yet another object of the present invention is to provide an efficient apparatus for performing battery equalization with a PV system controller.
Still another object of the invention is to provide a control system for maximizing the transfer of power from solar cells to-a load or battery bus in a simple and efficient manner.
Another object of the invention is to provide a control system for maximizing the transfer of power from solar cells to a load or bus which allows multiple solar cell array strings to be added to the system simply in a modular fashion.
Still another objective of the present invention is to provide short circuit protection for the charge controller.
Another object of the present invention is to reduce the losses in the wiring connected between the solar charge controller and PV panels.
Yet another object of the present invention is to provide protection against fault condition such as high current, high temperature etc in case of wrong configuration of the system connection.
Still another object of the present invention is to provide a modular structure of
controller.
Another object of the present invention is to provide a solar charge controller which can be extended to N number of PV arrays.
Yet another object of the present invention is to provide communication interface for the system.
Still another object of the present invention is to provide complete monitoring and controlling facility from local and remote location.
Another object of the present invention is to provide the visual indication for each individual PV array control.
Yet another object of the present invention is to provide the visual indication which can show the state of individual PV array voltage and current as well as charging state of the battery.
Another object of the present invention is to provide protection in case of high battery voltage.
Yet another object of the present invention is to provide protection in case of power device failure.
Still another object of the present invention is to provide reverse current flow protection from the battery to PV arrays.
STATEMENT OF INVENTION
According to this invention there is provided a the method and apparatus to control multiple PV array comprising of includes PV array input section, battery bank input section, power supply section to provides the supply to control section, control section to control the isolated supply with a PWM signal, PV array voltage & current sense section interfaces PV voltage, battery voltage and current signals to control section, battery voltage & current sense section, user configurable boost float voltage & equalization settings section, switching device/ Power Module section having the switching devices power connected between the PV arrays and battery bank controlled by the PWM signals from the main controller through gate driver section i.e. PWM driver section, display interface section & communication interface section is connected through communication port.
SUMMARY OF THE INVENTION
In order to overcome the above mentioned problems and to achieve the said objects, the present invention provides a system and method for controlling the power output of a solar array string which includes a peak power tracker unit coupled between a solar array string and a load or battery bus. The invention provides a method and apparatus to control multiple PV array. The charge controller is based on advance microcontroller/ digital signal controller. The main controller is responsible for complete operation and control of the charge controller. The system comprises of different blocks such as PV array input, battery input, switching device / Power Module section, main controller section, PV and
battery current and voltage sensing, isolated DC supply section, boost & float setting for the charge controller, display and communication interface section.
In one aspect of the present invention, the main controller senses the PV voltage/current, battery voltage/current and the settings for the charge controller and temperature. Based on these sense signals, it controls the battery charging with the help of pulse width modulation (PWM) scheme. The main controller senses the PV voltage for each of the connected PV arrays to find out how many arrays are connected there after, based on the battery state and settings, the main controller operates the switching devices for each individual PV array through PWM. The main controller monitors the PV voltage and current for each individual array to control the charging. The battery charging process is a multistage charging control with manual and automatic equalization options.
The main controllers also monitor the temperature of the switching devices so as to avoid the failure of devices due to excessive temperature. The charge controller gives audio visual alarms in case of abnormal conditions such as high temperature and current. All the system parameters such as PV voltages, battery voltages, currents and battery charging state are displayed on the LCD. Communication interface is also provided for monitoring and controlling of the charge controller. The controller provides protection in the case of PV array voltage or battery voltage reverse connections and high current from PV array to the batteries. In the case of high current, the charge controller limits the current to protect the connected battery bank and the system itself.
All the information of the charge controller can be accessed through a PC via monitoring and controlling software. The data can also be logged on the PC to view and analyze the system performance.
The charge controller can control up to N channels of PV array wherein one of the embodiment N is equal to four and because of the modular structure the configuration can be extended to any number by using multiple modules together. All the modules can be connected through communication channel to share information and data monitoring and control.
In another embodiment of the present invention, display devices can be liquid crystal display (LCD), light emitting diode (LED), computer and touch screen
In other embodiment of the present invention, Communication interface can be RS232, USB, CAN, Ethernet or any other communication interface.
In still another embodiment of the present invention, the number of panels can be 1 to
N in the string.
In other embodiment of the present invention, the charge controller provides display for all the system parameters such as but not limited to connected PV array voltages and currents, battery voltage and current along with battery charging state.
In still another embodiment of the present invention, the system can have common positive configuration.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Fig 1 shows the block diagram for the charge controller
Fig 2 shows the block diagram of the system with multiple PV array connected with the charge controller.
Fig 3a, 3b, 3c, 3d and 3e shows flow chart for the operation multiple PV array based charge controller.
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS:
Reference may be made to fig 1 which'shows the block diagram for the charge controller 100. The various section of the system include PV array input section 101, battery bank input section 102, power supply section 103, control section 104, PV array voltage & current sense section 105, battery voltage & current sense section 106, user configurable boost float voltage & equalization settings section 107, switching device / Power Module section 108, PWM driver section 109, display interface section 110 & communication interface section 111. Communication interface section 111 connects PC 112 to the controller for monitoring and data logging. The power supply section 103 comprises of an isolated power supply derived from the battery bank 102 voltage. This section 103 provides the supply to control section 104 and switching section / Power Module 108 along with various other sections of the system 100. The main controller 104 controls the isolated supply 103 with a PWM signal. The PV voltage, battery voltage and current signals are interfaced to the main controller 104 through PV sense section 105 and battery sense section 106 respectively. The switching device / Power Module section 108 contains the switching devices / Power Module connected between the PV arrays 101 and battery bank 102 controlled by the PWM signals from the main controller 104 through gate driver section 109.
The bulk/ float voltage of the battery can be set through the programmable user setting provided in the boost float voltage and equalization section 107 with the help of variable resistors. Heat sink temperature along with ambient and battery temperature are monitored by the main controller 104 with the help of temperature sensors 113. The battery connect/disconnect unit 115 is used to isolate a PV array during some kind of problem such as semiconductor failure, High temperature and high charging current conditions etc. The reverse current flow protection unit 114 protects the system in the night from the current from battery to the PV array which can damage the PV array.
The main controller 104 senses the PV voltage/current, battery voltage/current and the settings for the charge controller 104 and temperature. Based on these sense signals, it controls the battery charging with the help of pulse width modulation (PWM) scheme. The main controller 104 senses the PV voltage for each of the connected PV arrays 101 to find out how many arrays are connected. Thereafter, based on the battery 102 state and settings, the main controller 104 operates the switching devices / Power Module 108 for each individual PV 101 array through PWM. The main controller 104 monitors the PV voltage and current for each individual array to control the charging. The battery 102 charging process is a multistage charging control with manual and automatic equalization options.
The main controllers 104 also monitor the temperature of the switching devices / Power Module 108 so as to avoid the failure of devices due to excessive temperature. The charge controller 104 gives audio visual alarms in case of abnormal conditions such as high temperature and current. All the system parameters such as PV voltages, battery voltages, currents and battery charging state are displayed on the display such as but not limited to LCD 110. Communication interface 111 is also provided for monitoring and controlling of the charge controller 100.
In the case of high heat sink temperature, the main controller 104 starts operating the semiconductor switches 108 in PWM mode with reduced duty cycle and continuously monitors the temperature. If the temperature still increases, the duty cycle further reduces to zero. After the temperature again reaches below a threshold then the main controller again turns on the switches to charge the batteries from the PV array 101.
All the charge controller modules work independently of each other. In case of a fault event in one of the operating modules, only the module having problem is removed from the group by the main controller 104 of that module. As soon as the fault is recovered, the module is automatically connected back to the group of all other charge controller 100 modules.
The charge controller also provides protection in the case of PV array 101 voltage or Battery 102 voltage reverse connections and of high current from PV array 101 to the batteries 102. In case of high current, the charge controller 100 limits the current to protect the connected battery bank 102.
The charge controller 100 can also switch on semiconductor 108 devices in case of
failure of the devices such as shorting etc. In such a condition, the main controller 104
detects the condition even when the duty cycle of the devices is reduced to zero and the
charging current still flows from PV array 101 to the batteries .102. The main controller
104 operates the contractors in the battery 102 and connects/ disconnects block to isolate
the batteries 102 from the system. ,
The PV 101 current and the battery 102 current are measured using the shunt resistances on the high side. The output of the shunts is provided to the operational amplifier. The current sense signal for the solar charge controller 100 is provided by converting the
voltage drop across the shunts to a proportional current by driving a transistor connected at the output of the rail to rail operational amplifier. This current is converted to sense voltage by dropping it across a resistance. This signal is then forwarded through the operational amplifier buffers to the analog to digital channels. The battery high current signal is generated through the comparator attached at the output of the battery current sense 106.
All the information of the charge controller 100 is accessed on the PC 112 through monitoring and controlling software. The data is also logged on the PC 112 to view and analyze the system performance. This method provides fault tolerant and robust design to the user.
Fig 2 shows the block diagram of the system with multiple PV array connected with the
charge controller 200. Multiple solar cell arrays (1 N) 101 are connected in parallel to
power a load or battery 102. The modularity of the system is provided.. Additional solar array strings 101 can be added to the system. Interface connects and allows the controller
104 to output control signals such that each solar cell array string (1 N) 101 may be
controlled individually.
Battery charging control is a fuzzy logic based multiple stages charging control with temperature compensation and auto/ manual equalization to keep the battery 102 charged. When the battery 102 voltage is below the boost voltage setting, the charge controller 103 operates in the bulk-charging mode. In this mode the charge controller 103 supplies the maximum available charging current to the battery 102. Once the boost voltage is achieved, the charge controller 103 operates in the absorption mode. In this mode the charge controller 103 maintains the battery voltage at the boost voltage level for a fixed interval of time and the current to the batteries is reduced in order to maintain the battery voltage 102.
After the fixed interval is completed, the charge controller 104 comes into float charging mode. In this case, the battery voltage is dropped to the float voltage level of the battery 102 and then regulated at that voltage. When the battery voltage drops below float voltage for a specified time, the charge controller again comes into bulk charging mode and the cycle repeats again.
The charge controller 104 provides a display 110 for all the system parameters such as connected PV array 101 voltages and currents, battery voltage 102 and current along with battery charging state on LCD display 110.
The charge controller 104 also provides the communication interface 111 for complete monitoring and controlling of the charge controller 104. The charge controller 104 can be connected to the PC 112 or any intelligent device through communication port 111 and all the parameters such as PV voltages and current of the array connected with the system, battery voltage, current and battery charging status etc can be read with the help
of monitoring and controlling software. The data can be logged to keep the record of the performance of the system over a period of time. The different settings such as boost voltage settings, equalization control etc for the batteries can be done through the monitoring software.
Fig 3 shows a control flowchart of the present invention. The charge controller starts after being powered up from the battery connected. In case the battery connections are reversed, the chare controller gives the indication for battery reverse protection. Once the battery is connected properly the main controller powers up. Various peripheral modules of the controller are initialized and different user configured settings are read. Then the system scans the number of PV arrays connected with the system. It also checks if any of the PV array are connected in reverse direction and gives the reverse PV connection indication. After detecting the number of channels of PV array connected, the main controller regulates each channel sequentially so as to charge the connected battery bank.
When the battery voltage is below bulk voltage setting, the main controllers operate the semiconductor switches to supply the batteries maximum available charge current from the PV array. As the voltage reaches above bulk voltage, the solar charge controller regulates the battery voltage at bulk level for specified time and this mode is called absorption mode. After the specified time, the battery voltage is reduced from bulk voltage to float voltage by reducing the duty cycle of the operating switches.
The high current condition and over heating of the semiconductor modules is also monitored for individual channel in case such an event takes place. The main controller takes corrective actions for example in case of high temperature the duty cycle is reduced to decrease the charging current and if the temperature still not decreases then that module is disconnected from the Battery through battery connect disconnect unit. As soon as the temperature reduces below a low threshold, the main controller automatically connects the battery to the system. Similarly, the high current for any particular connected PV channel is also monitored.
Conclusively, the present invention provides a solar charge controller with multiple solar cell array control, with advance fault .control in case of high current and high module temperature.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims: -

WE CLAIMS
A solar charge controller with multiple arrays comprising of PV array input section, battery bank input section, power supply section to provides the supply to control section, control section to control* the isolated supply with a PWM signal, PV array voltage & current sense section interfacing PV voltage, battery voltage and current signals to control section, battery voltage & current sense section, user configurable boost float voltage & equalization settings section, switching device/ Power Module section having the switching devices/power module connected between the PV arrays and battery bank controlled by the PWM signals from the main controller through gate driver section i.e. PWM driver section, display interface section & communication interface section connected through communication port wherein communication interface section connects PC to the controller for monitoring and data logging, and the PV voltage, battery voltage and current signals are interfaced to the main controller through PV sense section and battery sense section respectively.
1. A solar charge controller with multiple arrays as claimed in any of the preceding claims, comprising of means for sensing power output having a plurality of sensors for sensing the power output of respective solar array strings and producing respective sensed power output signals; and wherein the singular control circuit receives the sensed power output signals from each of the plurality of sensors.
2. A solar charge controller with multiple arrays as claimed in any of the preceding claims, wherein the battery charging is multistage charging control with manual and automatic equalization options.
3. A solar charge controller with multiple arrays as claimed in any of the preceding claims, wherein N number of array can be controlled by the system.
4. A solar charge controller with multiple arrays as claimed in any of the preceding claims, wherein said battery means comprises at least one battery of any capacity.
5. A solar charge controller with multiple arrays as claimed in any of the preceding claims, wherein said battery means comprises a plurality of batteries connected in parallel.
6. A solar charge controller with multiple arrays as claimed in any of the preceding claims, wherein monitoring and controlling software reads parameters such as but not limited to PV voltages and current of the array connected with the system, battery voltage, current and battery charging status.
7. A solar charge controller with multiple arrays as claimed in any of the preceding claims, wherein battery charging control is a fuzzy logic based multiple stages charging control with temperature compensation and auto & manual equalization.
9. A solar charge controller with multiple arrays as claimed in any of the preceding claims, wherein heat sink temperature is monitored by the main controller with the help of temperature sensor, the battery connect/disconnect unit is used to isolate a PV array with some kind of problem such as semiconductor failure or wrong configuration of system, high temperature and high charging current and the reverse current flow protection unit protects the system in the night from the current from battery to the PV array which can damage the PVarray.
10. A solar charge controller with multiple arrays substantially as herein described with reference to the accompanying drawings.