Maximum power tracking solar power system

• US 6,369,462 B1
• Filed: 05/02/2001
• Issued: 04/09/2002
• Est. Priority Date: 05/02/2001
• Status: Expired due to Fees

• Current Assignee: Aerospace Corporation
• Original Assignee: Aerospace Corporation
• Inventors: Siri, Kasemsan
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US09/847,496
• Time in Patent Office: 342 Days
• Field of Search: 307/82, 307/86, 307/58, 307/51
• US Class Current: 307/51
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: H02J 1/102 being switching converters H02J1/108, H02J1/12 take precedence
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A maximum power tracker maximizes the power deliverable from a power source, such as a solar array using increasing, decreasing and maintaining states controlled by a set point signal modulated by a dither signal for stabilized regular power tracking during under demand conditions and maximum power tracking during periods with over demand conditions of a load. Multiple converters and respectively maximum power trackers can be coupled in parallel using shared bus control signal for fault tolerant equalized power conversion through the converters.

Claims

1. A system for providing power from a plurality of sources providing respective source powers at respective source currents at respective source voltages to a load receiving respective load powers at respective load currents at a load voltage, the load having variable amounts of load demand for the load powers, the sources providing variable amounts of the respective source powers, the system comprising,

a plurality of converters respectively coupled between the sources and the load, the converters for converting the respective source powers into the respective load powers, and

a plurality of maximum power trackers respectively connected to the converters for respectively controlling the source powers and the load powers, the maximum power trackers sensing the respective load currents and source voltages and respectively controlling the converters for maximizing the respective source powers to respective peak power points at respective peak power source voltages when the load demand exceeds the source powers, maximum power tracker increasing the source voltage for increasing the source power toward the peak power point when the source power is below the peak power point and when the source voltage is below the peak power source voltage and when the load demand exceeds the source power, the maximum power tracker decreasing the source voltage for increasing the source power toward the peak power point when the source power is below the peak power point and when and the source voltage is above the peak power source voltage and when the load demand exceeds the source power, the maximum power tracker maintaining the source voltage constant at the peak power source voltage when the source power is at peak power point and when the load demand exceeds the source power, the maximum power tracker generating a control signal for controlling the converter to control the source voltage for operating the source at the peak power point when the load demand exceeds the source power, maximum power tracker controlling the converter for peak power tracking when increasing or decreasing or maintaining the source voltage when the load demand exceeds the source power, the maximum power tracker regulating the load voltage at a regulated load voltage when the source power available from the source exceeds the load demand.

2. The system of claim 1 wherein the converters are connected together through a bus signal for equalizing the respective load currents, each of the converters respectively comprise,

a power stage having a converter input signal for controlling the respective converter output current as part of the load current and load voltage to the load,

an error amplifier for sensing the load voltage and generating an error signal for regulating the load voltage to a regulation voltage when the source powers exceed the load demand, the error signal driving the converter input signal and the bus signal during load voltage regulation, and

a coupling means for coupling together the control signal and the converter input signal and the error signal, the converter input signal being the control signal when the control signal is lesser than the error signal during the peak power tracking when the load demand exceeds the source powers, the converter input signal being the error signal when the control signal is greater than the error signal during load voltage regulation when the source powers available exceed the load demand, the bus signal being the error signal when the control signal is greater than the error signal during load voltage regulation.

3. The system of claim 1 wherein,

the error signal from one of the converters drives the bus signal to remaining ones of the converters for providing respective equal load currents among the converters for equal load current sharing during voltage regulation, and

the converter input signal of a respective converter being the respective control signal when the respective control signal is less than the bus signal when a respective source power is operated at the peak power point during peak power tracking of the respective converter providing less than the equal load current when the remaining converters provide the equal load currents during output voltage regulation.

4. The system of claim 1 wherein,

the maximum power tracker serves to maximize the amount of source power converted into the load power when the load demands exceeds the source power.