Method for Distributed Power Harvesting Using DC Power Sources
A system and method for combining power from DC power sources. Each power source is coupled to a converter. Each converter converts input power to output power by monitoring and maintaining the input power at a maximum power point. Substantially all input power is converted to the output power, and the controlling is performed by allowing output voltage of the converter to vary. The converters are coupled in series. An inverter is connected in parallel with the series connection of the converters and inverts a DC input to the inverter from the converters into an AC output. The inverter maintains the voltage at the inverter input at a desirable voltage by varying the amount of the series current drawn from the converters. The series current and the output power of the converters, determine the output voltage at each converter.
1 . An apparatus comprising:
a direct-current (DC)/direct-current power converter,
wherein the DC/DC power converter comprises converter inputs and converter outputs,
wherein the converter inputs are configured to be coupled to a DC power source,
wherein the converter outputs are configured to be coupled in series with a plurality of other DC/DC power converters thereby forming a serial string, and
wherein the DC/DC power converter is configured to adjust a voltage across the converter outputs according to an input power received at the converter inputs and voltage regulated across the serial string using an overvoltage protection circuit.
2 . The apparatus according to claim 1 , comprising an external sensor interface configured to receive data from an external sensor.
3 . The apparatus according to claim 2 , wherein the external sensor interface is configured to receive the data from at least one of an ambient temperature sensor, a solar radiance sensor, and a sensor from a neighboring solar panel.
4 . The apparatus according to claim 1 , wherein the DC power source comprises at least one solar panel.
5 . The apparatus according to claim 1 , wherein the DC power source comprises at least one battery.
6 . The apparatus according to claim 1 , wherein the DC/DC power converter is configured to receive the input power from the DC power source.
7 . The apparatus according to claim 1 , wherein the DC/DC power converter comprises a control loop that receives a feedback signal.
8 . The apparatus according to claim 1 , comprising a controller configured to:
monitor at least one of voltage and current at the converter inputs; and
determine a pulse width modulation (PWM) that extracts maximum power from the DC power source.
9 . The apparatus according to claim 1 , wherein the serial string is configured to output power to an inverter.
10 . The apparatus according to claim 1 , wherein the overvoltage protection circuit is configured to regulate the voltage across the serial string from increasing above a regulated level.
11 . The apparatus according to claim 1 , wherein the DC/DC power converter comprises one of: a buck converter, a boost converter, a buck plus boost converter, a flyback converter, or a forward converter.
12 . The apparatus according to claim 1 , comprising a controller configured to limit power output from the DC/DC power converter to a preset safe level until the controller detects a release signal.
13 . A system comprising:
an inverter comprising:
inverter inputs,
inverter outputs,
a direct-current (DC)/alternating-current (AC) converter, and
an overvoltage protection circuit,
wherein the inverter inputs are configured to be coupled across a serial string of a plurality of DC/DC power converters, each DC/DC power converter is configured to convert a DC input from a different one of a plurality of DC power sources to a DC output, wherein the overvoltage protection circuit is configured to set a regulated voltage across the inverter inputs, and wherein each DC/DC power converter of the plurality of DC/DC power converters is configured to adjust a voltage provided to the serial string according to an input power received by the DC/DC power converter and the voltage regulated by the overvoltage protection circuit.
14 . The system of claim 13 , wherein the plurality of DC power sources comprises at least one solar panel.
15 . The system of claim 13 , wherein the plurality of DC power sources comprises at least one battery.
16 . The system of claim 13 , wherein the overvoltage protection circuit comprises a control loop using a feedback signal to determine the regulated voltage.
17 . The system of claim 13 , wherein the DC/AC converter is configured to receive an input string power from the serial string using the inverter inputs.
18 . The system of claim 13 , wherein the overvoltage protection circuit is configured to prevent voltage across the serial string from increasing above the regulated voltage.
19 . The system of claim 13 , comprising a controller configured to limit power output from each DC/DC power converter to a preset safe level until a predetermined condition is reached.
20 . The system of claim 13 , comprising a controller configured to receive temperature data from a temperature sensor, wherein the temperature data is indicative of an overheating condition of one of the plurality of DC power sources, and transmit at least one communication indicative of the overheating condition to a central analysis station.