Maximum Power Point Tracking Charge Controller with Coupled Inductor Multi-phase Converter

• US 20100264869A1
• Filed: 04/17/2009
• Published: 10/21/2010
• Est. Priority Date: 04/17/2009
• Status: Active Grant

• Current Assignee: Morningstar Incorporated
• Original Assignee: Morningstar Incorporated
• Inventors: Dubovsky, Stephen
• Granted Patent: US 8,164,299 B2
• Time in Patent Office: Days
• US Class Current: 320/102
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A maximum power point tracking (MPPT) charge controller for photovoltaic (PV) systems employs a maximum power point tracking algorithm for tracking the maximum power point voltage of a PV array at which the PV array produces maximum power voltage, and a buck converter for converting the maximum power voltage to the voltage required to charge one or more batteries. The buck converter includes multiple buck converter phase configurations phase shifted from one another. Each of the buck converter phase configurations has a phase inductor, and the phase inductors are combined on a single core to form a coupled inductor. One of the buck converter phase configurations is intentionally temporarily shut down when the output power is low. A first switch or a second switch of the buck converter phase configuration that is intentionally temporarily shut down is turned on to conduct electrical current when predetermined conditions are satisfied. A method of controlling battery charging in a photovoltaic system involves operating a coupled inductor multi-phase buck converter of a charge controller so that one of the buck converter phase configurations is intentionally temporarily shut down when the power output is below a predetermined value.

Claims

1. A maximum power point tracking charge controller for photovoltaic systems, comprising

a maximum power point tracking charge controller for electrical connection to a photovoltaic array including one or more photovoltaic modules and to a battery bank to control charging of the battery bank with electricity produced by the photovoltaic array, said charge controller having a maximum power point tracking algorithm for tracking the power point voltage of the photovoltaic array at which the photovoltaic array produces maximum power, said charge controller having a multi-phase buck converter for receiving voltage input from the photovoltaic array and for supplying voltage output from said buck converter to charge the battery bank, said buck converter converting the voltage input to a voltage output that matches the voltage required by the battery bank for charging, said buck converter storing electrical energy when the voltage input is greater than the voltage required by the battery bank for charging, said buck converter comprising multiple buck converter phase configurations phase shifted from one another, each of said buck converter phase configurations having a phase inductor and first and second switches, said phase inductors being combined on a single core to form a coupled inductor.

2. The maximum power point tracking charge controller recited in claim 1 wherein said buck converter comprises two buck converter phase configurations phase shifted 180°

from one another.

3. The maximum power point tracking charge controller recited in claim 2 wherein said buck converter is a 15 Amp buck converter and each of said buck converter phase configurations is a 7.5 Amp buck converter phase configuration.

4. The maximum power point tracking charge controller recited in claim 2 wherein one of said buck converter phase configurations is intentionally temporarily shut down when the current output is below a predetermined current output.

5. The maximum power point tracking charge controller recited in claim 4 wherein said buck converter has an equivalent leakage inductance and an equivalent magnetizing inductance, said one of said buck converter phase configurations that is intentionally temporarily shut down includes a first diode and a second diode, said first diode being turned on to conduct electrical current while said one of said buck converter phase configurations is intentionally temporarily shut down and when (voltage input/voltage output)>

2+(equivalent leakage inductance/equivalent magnetizing inductance).

6. The maximum power point tracking charge controller recited in claim 5 wherein said second diode is turned on to conduct electrical current while said one of said buck converter phase configurations is intentionally temporarily shut down and when 1<

(voltage input/voltage output)<

1+(equivalent magnetizing inductance/(equivalent leakage inductance+equivalent magnetizing inductance)).

7. The maximum power point tracking charge controller recited in claim 1 wherein said coupled inductor has a coupling ratio between said phase inductors, said coupling ratio being mid way between zero coupling and 100% coupling.

8. The maximum power point tracking charge controller recited in claim 1 wherein said charge controller includes a housing having an overall length substantially equal to 6.64 inches, an overall width substantially equal to 2.25 inches, and an overall height substantially equal to 2.86 inches.

9. The maximum power point tracking charge controller recited in claim 1 wherein said charge controller is capable of charging a 12/24 Volt system battery from any one of a 12 Volt, 24 Volt or 36 Volt photovoltaic array.

10. A maximum power point tracking charge controller for photovoltaic systems, comprising

a maximum power point tracking charge controller for electrical connection to a photovoltaic array including one or more photovoltaic modules and to a battery bank including one or more batteries to control charging of the battery bank with electricity produced by the photovoltaic array, said charge controller having a maximum power point tracking algorithm for tracking the maximum power point of the photovoltaic array at which the photovoltaic array produces maximum power voltage, said charge controller having a multi-phase buck converter for receiving the maximum power voltage from the photovoltaic array as voltage input to said buck converter and for supplying voltage output from said buck converter to charge the battery bank, said buck converter converting the voltage input to a voltage output that matches the voltage required by the battery bank for charging, said buck converter storing electrical energy when the voltage input is greater than the voltage required by the battery bank for charging, said buck converter comprising multiple buck converter phase configurations phase shifted from one another, each of said buck converter phase configurations having a phase inductor, said phase inductors being combined on a single core to form a coupled inductor, one of said buck converter phase configurations being intentionally temporarily shut down when the power output is below a predetermined power output.

11. The maximum power point tracking charge controller recited in claim 10 wherein said one of said buck converter phase configurations is intentionally temporarily shut down when the power output is below 30 Watts for a 12 Volt system battery and below 60 Watts for a 24 Volt system battery.

12. The maximum power point tracking charge controller recited in claim 11 wherein said buck converter has an equivalent leakage inductance and an equivalent magnetizing inductance, said one of said buck converter phase configurations that is intentionally temporarily shut down includes a first diode and a second diode, said first diode being turned on to conduct electrical current while said one of buck converter phase configurations is intentionally temporarily shut down and when (voltage input/voltage output)>

2+(equivalent leakage inductance/equivalent magnetizing inductance).

13. The maximum power point tracking charge controller recited in claim 12 wherein said second diode is turned on to conduct electrical current while said one of said buck converter phase configurations is intentionally temporarily shut down and when one 1<

(voltage input/voltage output)<

1+(equivalent magnetizing inductance/(equivalent leakage inductance+equivalent magnetizing inductance)).

14. The maximum power point tracking charge controller recited in claim 13 wherein said buck converter comprises two buck converter phase configurations phase shifted 180°

from each other.

15. The maximum power point tracking charge controller recited in claim 14 wherein said buck converter is a 15 Amp buck converter and each of said buck converter phase configurations is a 7.5 Amp buck converter phase configuration.

16. A method of controlling battery charging in a photovoltaic system having a charge controller electrically connected to a photovoltaic array and to a battery bank, said method comprising the steps of

operating a maximum power point tracking algorithm of the charge controller to track the maximum power point voltage of the photovoltaic array at which the photovoltaic array produces maximum power;

supplying the maximum power voltage as voltage input to a buck converter of the charge controller that includes multiple buck converter phase configurations having phase inductors combined on a single core to form a coupled inductor;

operating the buck converter to convert the voltage input into voltage output that matches the voltage required by the battery bank for charging, said step of operating the buck converter including running the multiple buck converter phase configurations out of phase from one another when the voltage output is above a predetermined voltage output and intentionally temporarily shutting down one of the buck converter phase configurations when the voltage output is below the predetermined voltage output; and

supplying the voltage output from the charge controller to the battery bank to charge one or more batteries of the battery bank.

17. The method of controlling battery charging recited in claim 16 wherein said step of intentionally temporarily shutting down one of the buck converter phase configurations includes intentionally temporarily shutting down the buck converter phase configuration when the power output is below 30 Watts for a 12 Volt system battery and below 60 Watts for a 24 Volt system battery.

18. The method of controlling battery charging recited in claim 16 wherein said step of shutting down includes conducting electrical current across a first diode or across a second diode of the buck converter phase configuration that has been shut down depending on the value of voltage input/voltage output.

19. The method of controlling battery charging recited in claim 18 wherein the buck converter has an equivalent leakage inductance and an equivalent magnetizing inductance, and said step of conducting includes conducting electrical current across the first diode when (voltage input/voltage output)>

2+(equivalent leakage inductance) equivalent magnetizing inductance).

20. The method of controlling battery charging recited in claim 19 wherein said step of conducting includes conducting electrical current across the second diode and not the first diode when 1<

(voltage input/voltage output)<

1+(equivalent magnetizing inductance/(equivalent leakage inductance+equivalent magnetizing inductance)).