Claims:WE CLAIM:

1. A method of maximum power point tracking (MPPT) in a power generator, comprising:
providing a processor coupled through at least one controller to control a gate driver circuit, wherein the processor is programmed to implement a MPPT process that comprising:
measuring a PV current and a PV voltage of a power generator;
measuring an output power when a Brushless DC (BLDC) motor is connected with the power generator without rotating the BLDC motor;
comparing the output power with a preset power sufficient to run the BLDC motor;
running the BLDC motor at slow speed in speed control loop to find Jam if motor not able to run at set point speed;
setting a first MPPT point voltage equal to 80% of the open circuit voltage of power generator;
running the BLDC motor till the PV voltage reaches the first MPPT point voltage;
determining a voltage change in the PV voltage of power generator when a change in PV power is observed;
determining a second MPPT point voltage by increasing speed of the BLDC motor If the voltage change is greater than a threshold change value;
determining a second MPPT point voltage by decreasing speed of the BLDC motor If the voltage change is less than the threshold change value; and
replacing the value of first MPPT point voltage with the second MPPT point voltage.
wherein the maximum power point of the power generator is tracked when the voltage change is less than the threshold change value.

2. The method as claimed in claim 1, wherein the MPPT process further comprises comparing the PV voltage of the power generator with a preset startup voltage.

3. The method as claimed in claim 1, wherein increasing or decreasing the speed of the BLDC motor comprises adjusting PWM duty cycle of the driver circuit by the controller.

4. A system for performing the method of maximum power point tracking (MPPT) in a power generator, comprising:
a measurement circuit connected to the power generator;
at least one controller connected with the measurement circuit generating PWM control signals;
a gate driver circuit connected with the controller and configured to receive the generated PWM control signals from the controller;
an H-bridge connected between the power generator and the gate driver circuit, wherein the H-bridge comprises a plurality of MOSFET switches receiving gating signals from the gate driver circuit;
a Brushless DC (BLDC) motor connected with the H-bridge; and
a feedback circuit connected between the BLDC motor and the controller, and configured to provide a voltage feedback to the controller.

5. The system as claimed in claim 4 further comprises an input filter connected between the power generator and the H-bridge.

6. The system as claimed in claim 4, wherein the power generator is a photovoltaic power generation device.

7. The system as claimed in claim 4, wherein the controller is a microcontroller.
, Description:TECHNICAL FIELD
[0001] The present disclosure generally relates to a method of maximum power point tracking (MPPT) of photovoltaic power generators for a BLDC solar pump.

BACKGROUND
[0002] Solar Pumping system is powered from Photovoltaic generator. Photovoltaic (PV) power generators convert the light energy in to electrical energy. The controller is used between PV generator and pump to enhance the power extraction from PV generator. This enhancing technic is basically called as MPPT. To implement the efficient MPPT algorithm load characteristics need to be considered. Here load is BLDC motor with pump. The cost and complexity of system is highly dependent on the choice of MPPT implementation.

[0003] Maximum power point tracking of a PV cell in particular is challenging due to the nonlinear current-voltage characteristic and ever-changing nature of the irradiation source. Conventional MPPT systems use a process that finds the best operating point and creates a reference signal, or logical and relational operators, and are based on trial and error or seek and find to get the best operating point. These may be implemented in software running on microprocessors. Such approaches may lead to oscillation around the optimum point, which adversely impacts overall efficiency of the system. Such approaches may also demand a requirement of high accuracy of voltage current measurement as well as closed loop control. Moreover, trial and error approaches degrade efficiency for fast changing conditions.

SUMMARY
[0004] In one aspect of the present disclosure, a method of maximum power point tracking (MPPT) in a power generator is disclosed. The method comprises providing a processor coupled through at least one controller to control a driver circuit. The processor is programmed to implement a MPPT process. The MPPT process comprises the steps of: measuring a PV current and a PV voltage of a power generator, measuring a PV power when a BLDC motor is connected with the controller, comparing the PV power with a preset power sufficient to run the BLDC motor, running the BLDC motor at slow speed in speed control loop to find Jam if motor is not able to run at set point, setting a first MPPT point voltage equal to 80% of the open circuit voltage of the power generator and running the BLDC motor till the PV voltage reaches the first MPPT point voltage. The MPPT process further comprises the steps of determining a voltage change in the PV voltage of power generator when a change in PV power is observed, determining a second MPPT point voltage by increasing speed of the BLDC motor If the voltage change is greater than a threshold change value, determining a second MPPT point voltage by decreasing speed of the BLDC motor If the voltage change is less than the threshold change value and replacing the value of first MPPT point voltage with the second MPPT point voltage. During the process of steering, PV voltage to the preset power is monitored and a PV voltage generating a maximum PV power of the power generator is monitored, and added as a new MPPT point voltage. Once the power generator is steered to the new MPPT point, the MPPT process waits for threshold change value to start again MPPT tracking.

BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The detailed description is described with reference to the accompanying figures.
[0006] Figures 1a -1b, illustrate a flow chart of a method of maximum power point tracking (MPPT) in a power generator in accordance with an exemplary embodiment of the present disclosure.
[0007] Figure 2, illustrates a block diagram of setup for performing the method of maximum power point tracking (MPPT) in a power generator in accordance with the present disclosure.

DETAILED DESCRIPTION
[0008] A method of maximum power point tracking (MPPT) in a power generator and a system for performing the same are disclosed. The power generator may be a photovoltaic or solar power generator having a plurality of panels. During start up, power availability of the power generator can be checked and power of the solar power generator is further then fed to the motor. A MPPT point voltage is determined and monitored, a new MPPT point voltage is determined upon a change of power of the solar power generator due to atmospheric conditions.

[0009] Referring to figures 1a – 1b, illustrates a flow chart of a method of maximum power point tracking (MPPT) in a power generator in accordance with an exemplary embodiment of the present disclosure. The method comprises providing a processor programmed to implement a MPPT process. The power generator may be a photovoltaic power generation device comprising a single photovoltaic (PV) panel or of a plurality of series-parallel interconnected photovoltaic (PV) panels. The MPPT process comprises the steps of measuring a PV current and a PV voltage of the power generator, measuring a PV power when a Brushless DC (BLDC) motor is connected with the power generator, comparing the PV power with a preset power sufficient to run the BLDC motor and running the BLDC motor at slow speed in speed control loop to find jam if the BLDC motor is not able to run at a set point speed. The measurement of PV power is performed with the Brushless DC (BLDC) motor connected as a DC load, if the PV voltage is greater than a preset startup voltage.

[0010] The MPPT process further comprises the steps of setting a first MPPT point voltage equal to 80% of the open circuit voltage of power generator and running the BLDC motor till the PV voltage reaches the first MPPT point voltage. When a change in PV power of power generator is observed, a new MPPT point voltage is determined by adjusting PWM duty cycle of a PWM control signal supplied to a driver circuit. A voltage change in the PV voltage of power generator is determined when a change in PV power is observed and a second MPPT point voltage is determined by increasing speed of the BLDC motor if the voltage change is greater than a threshold change value. A second MPPT point voltage is also determined by decreasing speed of the BLDC motor if the voltage change is less than the threshold change value. During the process of steering, PV voltage to the preset power is monitored and a PV voltage generating a maximum PV power of the power generator is monitored, and added as a new MPPT point voltage. Once the power generator is steered to the new MPPT point, the MPPT process waits for threshold change value to start again MPPT tracking. For example, the threshold change value is 2 V. During +/- 2V volt steering of the power generator, the PV power is monitored and the PV voltage yielding maximum power is found. The value of first MPPT point voltage is replaced with the second MPPT point voltage. The second MPPT point voltage is a new MPPT point voltage.

[0011] Referring to figure 2, illustrates a block diagram of a system 200 for performing the method of maximum power point tracking (MPPT) in a power generator in accordance with the present disclosure. The system 200 comprises the power generator 210, at least one controller 230, a gate driver circuit 240 and an H-bridge 250. The power generator 210 is a photovoltaic power generation device. The photovoltaic power generation device may comprise a single photovoltaic (PV) panel or of a plurality of series-parallel interconnected photovoltaic (PV) panels. The controller 230 generates PWM control signals of variable duty-cycle and provides to the gate driver circuit 240. The controller 230 may be a microcontroller having a memory unit stored with instructions to perform the MPPT process as mentioned in the embodiment and the motor running process. The system 200 further comprises a measurement circuit 260 connected with the photovoltaic power generation device, an input filter 220 (it maybe a capacitor filter for reducing ripple voltage) connected between the photovoltaic power generation device and the H-bridge, and a Brushless DC (BLDC) motor 280connected with the photovoltaic power generation device through the H-bridge 250 and the input filter 220. The measurement circuit 260 may comprise a plurality of resistors connected in series and parallel for measuring current and voltage. The measurement circuit 260 measures a PV voltage and a PV current of the power generator, and a PV power when the BLDC motor 280 is connected in the system as a DC load. The measured analog values may be converted into digital values using an analog to digital converter ADC (not shown). The digital measurement values are provided to the controller. The gate driver circuit 240 receives PWM control signals and provides gating signals to the H-bridge. The system may further comprise a feedback circuit 270 providing a voltage feedback to the controller 230, thereby comparison with the PV voltage is performed to deliver a maximum power point voltage at each cycle of operation.

[0012] The H-bridge comprises a plurality of power switches driven by gating signals from the driver circuit. The power switches are preferably a plurality of MOSFET switches. Further the processor is coupled through the at least one controller to control the driver circuit. The processor may comprise a memory unit configured to store a program of instructions. The processor is programmed to implement the MPPT process mentioned in the flow chart of figure 1. The speed of the BLDC motor is either increased or decreased by adjusting PWM duty cycle of PWM control signal provided to the driver circuit through a controller.

[0013] The present disclosure provides the MPPT process for tracking a maximum power point for the photovoltaic power generation device. Further the open loop operation of this method involves an easy implementation by using the simple hardware. The open loop operation moreover does not require very high accuracy of measurements as well as provides stable operation and does not produce any unnecessary oscillations. The MPPT process checks the output PV power with the preset power sufficient available for BLDC motor operation, Thus the power availability check without running the BLDC motor prevents BLDC motor running at low power and improves life time of the BLDC motor. Further the new MPPT point is searched on both directions of current or previous MPPT point.

[0014] Although the present disclosure has been described in the context of certain aspects and embodiments, it will be understood by those skilled in the art that the present disclosure extends beyond the specific embodiments to alternative embodiments and/or uses of the disclosure and obvious implementations and equivalents thereof. Thus, it is intended that the scope of the present disclosure described herein should not be limited by the disclosed aspects and embodiments above.