FIELD OF INVENTION
The invention relates to a heavy-duty three phase inverter particularly used for an application in the telecom industry.
PRIOR ART
A conventional three-phase inverter aims to transform DC power to three-phase AC power to drive a load. The three-phase AC inverter consists of a plurality of transistors coupled in parallel. These transistors are generally insulated gate bipolar transistors (IGBTs). The gates of the transistors are controlled by first PWM control signals, the upper and lower arm control signals corresponding respectively to R, S and T phases. Taking the R phase for an example, the transistors are driven by gate drivers.
Parallel coupling is accomplished and controlled by coupling two or more sets of IGBTs of the same make & model number. Only one gate control signal is required to drive two or more transistors that are coupled in parallel at the same time.
However, the inverter described above still associated with some technical problems, such as current distribution, malfunctioning, low efficiency and capacity. Details on these are elaborated as follows:
Since the static and dynamic characteristics of IGBTs are not always the same, controlling with direct parallel operation results in different current flowing through two or more IGBTs when turned on in a static condition or switching dynamically. As a result, current distribution in the IGBTs is not equal. In serious conditions, the IGBTs could overheat and burn out.
As the transistors use the same set of control signal to pass through gate control circuits and drive the IGBTs, therefore if one IGBT is opened or the actuation circuit is abnormal (such as signal interruption), in terms of the parallel structure, as long as one IGBT is turned on normally, the overall output actuation is not affected. The actual load current waveform is also the same as the normal signal. Hence, malfunctioning of the IGBT cannot be detected, and protection of the IGBT is difficult. Isolation of the malfunction is also not easy. Moreover, when one IGBT malfunctions, excessive current could flow through another IGBT. When the malfunction is not detectable, the other IGBT could burn out. Reliability is thus lacking.
The power loss of the general inverter can be classified as conduction loss and switching loss (including turn-on losses and turn-off loss). In general, a higher switching frequency of the IGBT has a more desirable output waveform, but the power loss is also greater, and the overall efficiency is lower. For an inverter of a greater capacity, to maintain a high switching frequency to achieve a desired waveform output is difficult.
In term of capacity, the safety current of the IGBT must be reduced as the switching frequency increases. Moreover, the dividing current is not equal when the IGBTs are coupled in parallel. Hence, the total safety current has to be reduced.

Pulse width modulator (PWM) inverters are used in three phase bridges, H-bridges, and half-bridge configurations. The bus capacitors, typically electrolytic, consist of two or more capacitors connected in series or parallel that is fed from a rectifier or actively switched front end section.
The existing inverters are not user configurable conveniently. When they change the battery, the charging & other settings are also required to be changed which require replacement of hardware & software. Keeping a track of these is not only difficult for the manufacturer but also cumbersome.
Some of the available inverters do not have monitoring & controlling software interface. The problem faced by using these inverters is that when the battery goes low it shuts down the system connected to it abruptly. This results in the failure of system & loss of revenue, which is not acceptable in a telecom site as the mobile network gets affected.
Some of inverters which claim to have monitoring & controlling software have the following drawbacks-
(a) Existing monitoring & controlling software interface is not real time. They do not
provide instantaneous values of the various parameters of the system. They cannot do
power audit. The product up-gradation is also not possible by these softwares.
(b) In the systems where remote monitoring and controlling is possible, an additional card
or hardware (SNMP and other like that) is required to be connected to the inverter
system. This increases the hardware as well as cost of the system.
Some of the available inverters for telecom applications do not meet the requirement for running telecom shelter sites with loads like Air conditioners, SMPS Power Plants, lighting loads etc. The main requirement of these systems is to provide uninterrupted power to telecom sites as they are very critical unmanned sites & also the best optimum usage of SMPS batteries & also to reduce /eliminate the run time of the backup generator for cost effectiveness. The prior art systems have short-comings as indicated and therefore, they do not adequately address the aforementioned problems.
OBJECTS OF THE INVENTION
The primary object of the present invention is to provide a customized & improved three phase power inverter and control method to facilitate high quality, low output total harmonic distortion operation of three phase power inverters, particularly when applied to non-linear, high harmonic content, and/or unbalanced loads, common in telecom sites.
Another object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry, which a very efficient, low cost and three phase power inverter for use in telecom application varying the connected load having high inrush current drawing needs or other very cost sensitive applications. Three phase power generation is through dual DSPs using PWM with space-vector modulation technique. The entire inverter function is controlled by the dual DSPs being used in the system.
Still another object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry further comprising a rectifier section connected to a three-phase 4 wire source for generating the DC source for charging the battery bank connected.
Yet another object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry for generating a balanced, regulated AC output, comprising a AC-DC converter, an inverter section for generating the regulated AC output from the DC source, a DSP control section connected to the inverter section for pulse width modulating the inverter, wherein the control section has a voltage loop and a current loop for each phase of the AC output, and in which the control section has a means of processing.
Further object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry comprising IGBTs to provide AC wherein the regulated AC output is three-phase. Although isolated gate bipolar transistor (IGBT) power switches are the preferred embodiment in high voltage inverter applications, other power switches used in the lower voltage applications (for example FETs) are within the scope of the invention.
Yet further object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry further comprising a digital signal processor (DSP) in the control section.
Yet further object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry comprising of a driver section to drive the inverter IGBTs wherein driver is controlled by DSP.
Yet further object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry, further comprising a three-phase filter connected to the regulated AC source.
Yet further object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry supplying DC power supply to different sections and drivers.
Yet further object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry wherein the control printed circuit board (PCB) of the present invention acts as a digital signal processor (DSP) based digital PWM with space vector modulated AC voltage and/or current regulator, with independent phase voltage and current control loops. Independent voltage loops control the line to neutral voltage of each phase output. In one embodiment voltage feedback is provided by three individual resistances and integrator capacitors to boost DC gain and thereby enhance DC offset voltage rejection. Independent current loops control the output phase currents. Current feedback is also provided by resistors and filter capacitor circuits for optimum system tuning. Both the voltage and the current loops have digitally selected proportional and integral terms, and the feedback circuits have analog phase lead. Thus, precise closed loop transient performance is accomplished.
Yet further object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry having prolonged life of battery bank as well as longer backup.

Yet further object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry which is efficiently operable especially for non-linear, high harmonic content, and/or unbalanced loads.
Yet further object of the invention is to propose a heavy-duty three phase inverter particularly used for an application in the telecom industry which is cost effective.
SUMMARY OF THE INVENTION
The present invention devised in consideration of the aforementioned background.
The present invention controls the operation of air conditioner based upon the ambient temperature of the telecom shelter which results in optimum usage of inverter battery & long backup from inverter.
The present invention controls the operation of the SMPS power plant based upon the battery status of the SMPS power plant resulting in long backup from the inverter & also good life of SMPS power plant battery bank.
The present invention also has additional generator start facility by forwarding command to generator through DSP so as to optimize the use of generator available & also to make sure that the telecom site operation goes on uninterrupted.
The present invention diagnoses the problem in the inverter for example the status of the battery, battery life, overload, short circuit, generator started etc. & sends a SMS to the telecom site operator for remedial action.
According to the invention, the unbalanced dividing current resulting from different IGBT characteristics may be resolved and the abnormal signal of one power transistor or gate driver may be detected easily through the current waveform.
According to the principle and aspect of the invention, the switching loss of the power transistor may be reduced, the overall efficiency may increase, the failure rate of the inverter may be reduced and the total reliability may increase.
According to the principle and aspect of the invention, the parallel capacity may be increased and the cost of the elements may reduce.
The present invention also provides real time management using internet, for an inverter connected to a computer. As the same DSP, that is used to control the inverter communicates with the computer based software, the real time parameters are transferred to the computer.
This is through the dedicated communication protocol that is implemented inside the DSP and also in the monitoring software. The DSP technology provides faster and precise control of inverter system for effective and safe mechanism. Through the DSP the product up-gradation is also possible as the commands are directly sent to the DSP. This web based facility is without any additional hardware thus reducing the hardware and also the cost of the system. The inverter control section is connected to a computer via any serial port communication cable or the USB cable or RJ45 cable. The inverter installed anywhere in the world can be centrally monitored and controlled by the user, provided it is connected to the
internet. The present invention also provides facility to monitor & control the inverter via mobile and remote.
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 a block diagram of the three phase inverter of the invention;
FIG. 2 shows the circuit diagram of three phase charger;
FIG. 3 shows the circuit diagram of SCR section;
FIG. 4 shows the circuit diagram of the DC/DC converter circuit;
FIG. 5 shows the circuit diagram of the DSP control card-Master;
FIG. 6 shows the circuit diagram of the DSP control-Slave;
FIG. 7 shows the circuit diagram of driver card;
FIG. 8 shows the circuit diagram of inverter IGBT section;
FIG. 9 shows the circuit diagram of switching circuit;
FIG. 10 shows the circuit diagram of the LCD interface with DSP;
F1G.11 shows the circuit diagram of front display (bar graph);
FIG. 12 shows the circuit diagram of front display (indicator);
FIG. 13 shows circuit diagram of RS-232 interface with DSP;
FIG. 14 shows the circuit diagram of RS-232 cable connection;
FIG. 15 shows a pictorial diagram of power management system controlled by web monitoring software using computer system;
FIG. 16 shows a pictorial diagram of power management system controlled by web monitoring software using mobile or remote;
FIG. 17 shows a pictorial diagram of GSM connectivity to the inverter;
FIG. 18 shows the flow of the software program pertaining to the operation of the invention for monitoring the system;
FIG. 19 shows the flow of the software program pertaining to the operation of the invention for controlling the various parameters of the system;
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
FIG. 1 is a block diagrammatic overview of one of the three phase power inverter and control method for generating a balanced and regulated AC output, comprising a three phase charger, AC-DC converter, an inverter section for generating the regulated AC output from the DC source, a DSP control section connected to the inverter section for pulse width modulating the inverter and DC/DC converter system supplying DC power supply to different sections and drivers.
This is useful in AC distributed power systems, typically in pulse width modulation (PWM) with space-vector technique, inverter power generation and/or conditioning applications. These are especially designed for telecom sites application to run loads like Air- conditioners, SMPS power plant and lighting loads etc. The three phase telecom inverter of the present invention is designed through dual DSPs using PWM with space vector modulation technique and with IGBT as power devices. These are three Phase input & three Phase output inverters.
The three phase power inverter and control method is illustrated as a system showing a power source, such as a three-phase configured AC source that connects to the charger section.
Referring to FIG. 2 the three phase charger provides isolation from the AC line through input transformer, as well as being a regulating source by sensing current of the SCR section.
Referring to FIG. 3 SCRs are true rectifiers and thus they only allow current through them in one direction. SCR-SCR modules are used to charge the battery from the mains power available. The charging is being controlled by the charger card which has- settings for battery charging voltage & charging current. Heavy-duty charger with charging current ranging from 20A - 200A is provided to charge the batteries. The charger will be sensing the battery voltage and have current limiting capabilities. The rectified AC then passes through the battery bank.
Referring to Fig. 4 the SMPS power supply cards takes battery voltage as input & provides isolated +5V & +15V supplies, which are used by DSP cards & IGBT driver cards to drive the inverter IGBTs.
Fig. 5 and Fig. 6 refer to DSP control card master and slave respectively. The dual DSPs carry out the entire inverter function. One processor may be referred to as. a DSP slave, or simply a slave, and the other may be referred to as a DSP master, or simply a master. The master is configured to monitor data regarding status of parameters of the inverter and to implement control commands so as to control operation of the inverter. The slave is configured to relay information between the communication port and the master processor. The DSP control card senses the input voltage, output voltage, output current and battery voltage and gets ambient temperature feedbacks. It generates three phase PWM with Space vector Modulation. Dual DSPs are used in these products to communicate with each other & exchange information. The output PWM signal is transmitted to the output inverter power switches via gate driver circuits.
Referring to Fig. 7 IGBT driver cards provide protection & increase current capability of PWM signals. The IGBT driver cards receive input signals from inverter control circuit (DSP) and provide output drive signals to inverter module IGBT. The two complementary PWM signals generated by the DSP cannot be high simultaneously thus this is controlled by the logic gates. IGBT driver card provides isolation between DSP side and IGBT side with the help of opto-couplers. If there is any short circuit or voltage drop in the IGBT side and VCE becomes greater than the specified value then the driver takes protection by isolating the DSP side and IGBT side. Since DSP does not have the sufficient current to drive the inverter, IGBT driver card increases the current capability of DSP.
Referring to Fig. 8 wherein inverter module includes multiple of IGBTs and capacitors depending on the capacity of the system. IGBTs provide faster speeds, better drive and output characteristics than power BJTs and offer higher current densities than equivalent high-powered MOSFETs. This type of circuit provides enhanced inrush current withstand capability. Module can double the modulation frequency of the inverter, reduce the switching loss and improve the system efficiency with minimum noise, leading to performance improvement and cost reduction of system. The inverter module IGBTs receive the DC power and provide regulated AC power at the power output. Control of the circuit is achieved by controlling the IGBTs by pulse width modulated (PWM) signals generated by the inverter DSP controller, via the isolated gate driver circuits.
Fig. 9 refers the circuit diagram of switching circuit and Fig. 10 is the circuit diagram of the LCD interface with DSP. The dual DSP control card provides data to be displayed on the LCD. The processor is configured to perform its various functions by reading and executing computer-readable and computer-executable software instructions stored in the memory. The master can further receive commands/instructions from the computer via the network and the slave and control portions of the inverter to implement the commands.
Fig.l 1 and Fig. 12 refer to the circuit diagram of front display (bar graph) and circuit diagram of front display (indicator). The front panel display comprising of 20x4 lines LCD, mimic diagram to indicate the status of input mains, output phase and bypass mode. It also displays the loads on the 3 phases using a bar graph with overload indications too. It also displays the battery level using bar graph, battery voltage; short-circuit condition and output low/high condition.
Fig. 13 and Fig 14 refer to circuit diagram of RS-232 interface with DSP and RS-232 cable connection. The dual DSP control card also connects to any serial communication port (say RS232) to monitor the inverter status on local or remote location. Potential free contacts are provided with intelligent DSP control for generator start, battery low protection and mains/ on battery status.
The isolation transformer is used to increase or decrease the voltage of the AC power from the inverter power module IGBT and to provide isolation between a load and the inverter. The isolation transformer is typically system dependant, the capacity of which is typically dependent on inverter output power specifications. The isolation transformer separates the input neutral & output neutral, thus any disturbance or fault in input does not affect the output. It also blocks the noise in neutral and provides galvanic isolation. The transformer output is filtered and is then available as a balanced, regulated three phase, 4 wire AC power output.
Current feedback as well as voltage feedback is taken from the transformer output. The three phase current feedback is connected directly to the inverter DSP for A/ D conversion. The three phase voltage feedback signals are connected to the DSP via resistor divider and filter capacitor signal conditioning circuits.
After conversion, the voltage feedback terms are summed with the voltage set point commands, resulting in voltage error signals. The voltage error signals are multiplied by the voltage proportional and integral terms. The resulting output is compared to the current limit term, clamped if required and then sent to the current loop.
Current feedback is taken from the inverter output phase current sensors, scaled and filtered, and the resulting current feedback signals, are fed to the DSP A-D converters.
There are numerous variables (such as PWM filter circuit, DC link voltage, desired output impedance and PWM carrier frequency) that will impact feedback compensation, and gain selections. However, there are certain guidelines that provide a general method of approximation for selecting critical components and gain terms for a variety of PWM inverter applications.
The other basic constituents of the inverter are three phase front panel mimic display card, front panel load & battery bar graph card, contactors & relay, current transformers, power transformers, blower and temperature sensor.
Current transformers are used to measure the input & output currents & control the function of inverter depending on the currents. It provides signal to the DSP card to cater to overload conditions.
The system contains fuzzy logic algorithms for inverter operation to run the air-conditioners, SMSP power plants & other loads, which help in providing the long backup from the inverter. The system has auto SMS sending facility wherein the inverter sends an SMS to the operator of the telecom shelter to take corrective action in case of low battery, generator started or any other problem with the inverter etc. The system has auto generator start facility wherein the generator is started when the inverter battery reaches a predefined level well above the battery low level & if the generator does not start, it sends an SMS to the operator to take necessary actions.
The output generated by these inverter are pure sine wave with regulated voltage & frequency i.e. voltage regulation within 1% & frequency regulation within 0.1%. Even at 100% unbalanced load, the output voltage regulation is within 2%.
These inverters have very high inrush bearing capability as compared to generators e.g., 200% for 5 Sec & 300% for 2 sec. These inverters can be run at 100% load continuously whereas generators are to be run at 80% load only, hence for the same load requirement a smaller capacity of inverter is required than a generator.
Operation of blower is one of the novel features of the invention as it operates only when it is required. It is controlled using a temperature sensor mounted on the heat sink. It operates only when the temperature of heat sink reaches 55 deg C & switches off when temperature comes down to 45 deg C. Hence, the life of Blower is enhanced & also power saving. The
blower is so located that it takes fresh cold air from bottom & flushes the air through the heat sink. Hence, cooling to the maximum is possible in the shortest possible time.
Present invention also provides real time web based remote monitoring as well as multiple user local monitoring for inverter with the help of Power Management Software using internet as shown in the fig 15 & 16.
Power Management Software includes:
1. Web based monitoring Application.
2. Local Monitoring Application.
With the help of web based monitoring software, the inverter installed anywhere in the world can be centrally monitored and controlled by the user. It supports all operating systems such as Windows version & various Linux, Solaris versions. A licensed copy of the software is installed and run on the computer connected to the power system via any communication cable (say RS-232/ USB / RJ-45) through which it starts receiving data. The unique and fully validated software solution allows various parameters of the systems to check and the system can be upgraded, including load and status of each system. The novel feature of the software is that it does not require any additional hardware like SNMP card for web monitoring. Even local monitoring is done by using TCP/ IP. Use of computer instead of SNMP provides two way communication and product up-gradation possibility which was not possible by using SNMP hardware as seen in the existing monitoring software. The Power Management Software not only controls the start/shutdown of the inverter but also provides control for various parameters in inverter and system up-gradation. The software is very useful for unmanned locations or mission critical application where power backup systems are installed and where their assured availability is essential and mission critical. Some of the examples are ATMs, Telecom towers; Satellite based systems, online process control equipments, fully networked chain of retail stores, chain of multiplexes, their supply chain systems. Such inherent flexibility lends itself for condition based operational utilization of power backup systems thus adding considerable value and enhancing the maintainability and assured availability of systems.
Local power monitoring software requires a serial connection between a computer & the system via serial port communication cable. Inverter control section is connected to the computer via any communication cable (say RS232) as shown in fig 15 & 16.
Referring to Fig. 17, the inverter also has the connectivity through GSM device. It provides connectivity of the inverter to the internet without a computer. Using this, the user can monitor & control the product from a remote location using his mobile phone. This feature is very useful at those remote locations where the user does not have a computer and wants to check the status of the inverter. It is also advantageous to monitor the inverter in households where computer is not available. Additional advantage of this facility is that it reduces the cost of the inverter and does not require additional telephone lines. The data is recorded locally by the monitoring system and relayed to the server via the GSM network. Using the password, user can retrieve his unit's data at any time with the help of internet anywhere in the world. Fig.l shows the connectivity of the GSM device with the inverter. GSM device is connected to the inverter via DSP through the RS232/ RJ45/ USB cable and through GPRS connectivity, data is transmitted to the remote locations.
The web monitoring software facilitates checking of various parameters in the form of digital and graphical representation. Data logging of these parameters can be ensured at defined time intervals say every 10 or 15 seconds. The flow chart in fig 18 & 19 presents the functioning of the software for monitoring and controlling the system.
The inverter data is processed in a central database. User can access the data records at any time using protected internet access. The important parameters of the inverter like input voltage, input frequency, output voltage, frequency, power, current, battery voltage, battery level, number of power cuts & their duration can be monitored on the mobile phone. It is also possible to switch ON/ OFF the inverter from a remote location. Also the output voltage, battery low level and load can be changed from a remote location. Under various alarm conditions, the system sends SMS to the predefined numbers so that corrective action can be taken. This is a very useful feature which allows the remote monitoring & control of the product.
Chief components of the Power Management Software
The Power Management Software comprises of the following two components
(A) Local Server application
(B) Local Client Application
(A) Local Server application performs communication with the inverter, its shutdown as well as that of local clients, emailing and broadcasting of inverter events
Interpreting Main Panel
The main panel display provides node information and information on the status of the power, inverter battery system, system operations, and communications. The display automatically detects the configuration of the inverter and adjusts itself accordingly.
The main panel is a graphical representation of the operational status of the system. Input arid output voltage, input and output frequencies are shown with the help of analog meters. Battery voltage and load % along with output current, output power and inverter capacity are indicated with the help of bar graphs.
It provides detailed information regarding the present power situation and controls features such as orderly system shutdown and configuring alerts. It also provides system shutdown time, review of the power event, battery management logs and handles other tasks.
Following are the utilities provided by the software and local server can configure the system accordingly
1. Data view
Data view uses bar graphs and text for each phase to show the power situation. The display is divided into sections as follows:
Output
Output information shows the actual output load on the inverter. The output section includes
the following:
• Status: Condition of the inverter battery
• % Load: Percentage of the inverter's calculated full load in use including overload
conditions
• Volts: Output voltage for the load including over voltage and under voltage conditions
• Hz: Output frequency for the load including high and low frequency conditions
Input
The input section is a green, yellow and red bar on a row below the output section showing
the utility power source voltage and limits. The colors on the display indicate whether the
power is within acceptable limits. If the voltage reading is in the green range it shows that the
inverter is operating on the utility power. Yellow or red range indicates that the work is to be
saved.
2. Battery Status and Load
Battery Status information provides description of .the status of the battery. Load feature gives the present load on inverter.
3. Secure Access
The Software provides secure access for a valid user to make changes in the Power Management Software Application.
4. Email Notification
User can configure Power Management software to send an email message to upto 4 people when an event occurs.
5. Data Log
Data Log provides the log of inverter parameters i.e. input and output voltage, input and output frequency, power, inverter status, output current, battery capacity, load and capacity at specified time interval.
6. Inverter Settings
Power Management Software provides the way to set some inverter settings like
• Output voltage/ output frequency as per requirement.
• Change in Battery low/ battery high protection.
• Disable/enable Buzzer.
• Change in high/ low cut level.
• Inverter Shutdown/ Restart.
7. Broadcasting Messages
User can configure Power Management Software to broadcast a notification message when an event occurs.
8. Customize Alerts
It can be used to change the text of an alert message or to change the response that system makes to alert.
9. Delay Times
User can change the delay time for message for e.g. 10, 20, 30, 40, 50 or 60 sec.
10. Client Connection
This option disables/ enables Client-Server communication.
11. Update User Information
Under this option user can update his/her personal information like name, company name, address, phone number etc.
12. Priority based Settings
Attached equipments to the inverter may be given two levels of priority namely Low and High. Time entered against this setting defines the time for low priority equipment to shutdown. The value for high priority equipment is double of this time.
13. Inverter Scheduler Settings
'Weekly shutdown schedule' can be used to shut down all or segments of the inverter load at a certain time each day. Periods when the system is scheduled to be ON are shown in orange. Periods when the system is scheduled to be off are shown in white.
14. Server Shutdown Settings
It sets the interval between the time the Power Management Application software begins to shut down of the Windows environment and the power from the inverter shuts off.
15. View Data Logged File
User can view the Logged file at any time. Data which is logged is as follows:
• Date
• Time
• Input and Output Voltage
• Input and Output Frequency
• Output Current
• Output Power
• Load percentage
• Total Units
• Ambient Temperature
• Capacity
• Battery Voltage
• Status
16. Connected Users List
Server lists the client's status, whether they are online or offline, client's name, priority and their IP addresses. Connected users show the number of clients online.
17. View Graphs
User can view 3 kinds of graphs
• Input & output voltage
• Input & output frequency
• Output power
This utility provides the following features-
• Auto and Manual saving of graph
• Plotting of input and output voltage, input and output frequency, output power
• Maximum and minimum value over a period of time
• Plotting of data from files
• Start and End Time at which user had actually started/ ended the plotting in graph
• Printing of the graph
(B) Local client application registers and communicates with the local server.
Interpreting Main Panel
The main panel displays node information and information on the status of the power, inverter battery system, system operations, and communications.
The main panel is a graphical representation of the operational status of the system. Input and output voltage, input and output frequency is shown with the help of analog meters. Battery voltage and load % are indicated with the help of bar graphs; besides output current, output power and inverter capacity.
It provides detailed information regarding the present power situation. It also provides system shutdown time, review of the power event and battery management logs.
Following are the utilities provided by the software and the local client can configure the system accordingly.
1. Data view
Data view uses bar graphs and text for each phase to show the power situation. The display is divided into sections as follows:
Output
Output information shows the actual output load on the inverter. The Output section includes the following:
• Status: Condition of the inverter battery
• % Load: Percentage of the inverter's calculated full load in use including overload
conditions
• Volts: Output voltage for the load including over voltage and under voltage conditions
• Hz: Output frequency for the load including high and low frequency conditions
Input
The input section is a green, yellow and red bar on a row below the output section showing
the utility power source voltage and limits. The colors on the display indicate whether the
power is within acceptable limits. If the voltage reading is in the green range it shows that the
inverter is operating on the utility power. Yellow or red range indicates that the work is to be
saved.
2. Battery Status and Load
Battery status information provides description of the status of the battery. Load feature gives the present load on inverter.
3. Update Server IP
Client has the permission to change the Server IP address. Connection gets closed as soon as user would change Server IP.
4. Update Priority
Client has, by default, priority 'Low', which can be changed. Clients are allowed to change their priority from 'Low' to 'High' and vice versa.
5. Update User Name and Password
Client can change his user name and password.
Now, if the user desires to monitor/ control the inverter system remotely he has to go through web monitoring. The web monitoring application includes -
1. Power Management Software that reads data from the DSP of inverter through RS-
232/RJ45/USB port.
2. Similarly live data of'N' number of inverter data are available on Server in every 3 to
10 seconds.
3. A valid user has to login on a specific website which will display list of all inverters.
4. "Details" link displays the live status and parameters of the product.
5. One can view the data log of product, date & time wise accordingly.
6. One can also view the summary of the product since installed. The summary contains
blackouts, brownouts, number of units drawn by load through inverter, review of grid
power in terms of fluctuations and number of outages.
7. Blackouts contains each and every moment when mains are not present.
8. Brownout contains duration of inverter mode when there is low voltage.

9. Other details can be viewed like:
• Input Voltage duration:
1. <180V
2. > 180V &< = 200V
3. > 200V &< = 230V
4. > 230V &< = 250V
5. > 250V &< = 270V
6. >270V
• Input Frequency duration:
1. < = 49.8 Hz
2. < = 49.5 Hz
3. < = 48Hz
4. > = 50.2 Hz
5. > = 50.5 Hz
• Output Power / Load duration:
1. < = 25%
2. 26%-50%
3. 51%-75%
4. 76%-100%
5. >*=101%
• Duration of Status i.e. duration of on mains/ on battery/ overload
conditions etc.
10. Charts of input voltage vs time, input frequency vs time, output voltage vs time,
output frequency vs time, battery voltage vs time, output power vs time, load vs time
and blackouts vs date are available for analysis.
11. One can send request code of particular product to retrieve live status of product
immediately.
12. Controlling can be done through web and mobile to-

• Set Output Voltage/ Output Frequency as per requirement.
• Change Battery Low/ Battery High protection.
• Disable/ Enable buzzer.
• Change High/ Low cut level.
• Shutdown/ Restart Inverter.
13. Local computers can also be controlled/ scheduled to shutdown by using TCP/ IP.
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 CLAIM:
1. A heavy-duty three phase inverter particularly used for an application in the telecom
industry comprising a three phase charger, AC-DC converter, an inverter section for
generating the regulated AC output from the DC source, a DSP control section
connected to the inverter section for pulse width modulating the inverter and DC/DC
converter system supplying DC power supply to different sections and drivers.
2. A heavy-duty three phase inverter as claimed in claim 1 comprising of dual DSPs
using PWM with space vector modulation technique with IGBT as power devices.
3. A heavy-duty three phase inverter as claimed in claim 1 or 2 comprising of DSP
control card master and slave and IGBT driver cards.
4. A heavy-duty three phase inverter as claimed in any of the preceding claims wherein
the IGBT power device is connected to an isolation transformer, output of which is
filtered to be available as a balanced, regulated three phase, 4 wire AC power output.
5. A heavy-duty three phase inverter as claimed in any of the preceding claims wherein
output generated by the inverter are pure sine wave with regulated voltage and
frequency with voltage regulation within 1% and frequency regulation within 0.1% in
which even at 100% unbalanced load, the output voltage regulation is within 2%.
6. A heavy-duty three phase inverter as claimed in any of the preceding claims wherein
the system also has the connectivity through GSM modem to monitor & control the
inverter from a remote location using mobile phone/internet.
7. A heavy-duty three phase inverter particularly used for an application in the telecom
industry as claimed in claim 1 further comprising auto generator start facility wherein
the generator is started when the inverter battery reaches a predefined level well
above the battery low level.
8. A heavy-duty three phase inverter particularly used for an application in the telecom
industry as claimed in claim 1 further comprising potential free contacts for sending
status of battery low protection, on mains/ on battery status and overload/short circuit
protection.
9. A heavy-duty three phase inverter particularly used for an application in the telecom
industry as claimed in claim 1 further comprising auto SMS sending facility wherein
the inverter sends an SMS to the operator of the telecom shelter to take corrective
action in case of low battery, generator start or any other problem with the inverter.
10. A heavy-duty three phase inverter particularly used for an application in the telecom
industry substantially as herein described with reference to the accompanying
drawings