Solar drive system and method for tracking the maximum power point of a photovoltaic array

• US 10,581,340 B2
• Filed: 08/01/2016
• Issued: 03/03/2020
• Est. Priority Date: 07/31/2015
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Carter, Robert, Quinn, William John
• Primary Examiner(s): Ahmed, Yusef A
• Application Number:
  US15/744,118
• Publication Number:
  US 20180203478A1
• Time in Patent Office: 1,310 Days
• CPC Class Codes: F03G 6/001 having photovoltaic cells
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: Y02E 10/46 Conversion of thermal power into mechanical power, e.g. Rankine, Stirling or solar thermal engines
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A solar drive system, having: at least one photovoltaic array generating a DC current; at least one inverter electrically connected to the photovoltaic array for inverting the DC current into an AC current; at least one electric motor electrically connected to the inverter for supplying the electric motor with the AC current; and at least one device for determining a present rotational frequency of the electric motor; wherein the inverter is configured to track a maximum power point of the photovoltaic array by performing a Perturb and Observe Maximum Power Point Tracking method and to determine a step direction of the Perturb and Observe Maximum Power Point Tracking method using the determined present rotational frequency of the electric motor.

Claims

1. A solar drive system, comprising:

at least one photovoltaic array generating a DC current;

at least one inverter electrically connected to the at least one photovoltaic array for inverting the DC current into an AC current; and

at least one electric motor electrically connected to the at least one inverter which supplies the at least one electric motor with the AC current;

at least one sensor element for detecting a present rotational frequency of the at least one electric motor, the at least one sensor element being arranged on the at least one electric motor and being connected to the at least one inverter by wire or wireless;

wherein the at least one inverter is configured to track a maximum power point of the at least one photovoltaic array by performing a Perturb and Observe Maximum Power Point Tracking method and to determine a step direction of the Perturb and Observe Maximum Power Point Tracking method using the present rotational frequency of the at least one electric motor.

2. A solar drive system, comprising:

at least one photovoltaic array generating a DC current;

at least one inverter electrically connected to the at least one photovoltaic array for inverting the DC current into an AC current; and

at least one electric motor electrically connected to the at least one inverter which supplies the at least one electric motor with the AC current;

wherein the at least one inverter is configured to detect a present rotational frequency of the at least one electric motor from a frequency of the AC current of the at least one inverter using a frequency setpoint of the at least one inverter to detect the present rotational frequency from the frequency of the AC current supplied from the at least one inverter to the at least one electric motor;

wherein the at least one inverter is configured to track a maximum power point of the at least one photovoltaic array by performing a Perturb and Observe Maximum Power Point Tracking method and to determine a step direction of the Perturb and Observe Maximum Power Point Tracking method using the present rotational frequency of the at least one electric motor.

3. A method for tracking a maximum power point of a photovoltaic array driving an electric motor through an inverter, comprising:

detecting a present rotational frequency of the electric motor;

wherein detecting the present rotational frequency of the electric motor comprises direct measurement by a sensor;

performing a Perturb and Observe Maximum Power Point Tracking method to track the maximum power point of the photovoltaic array; and

determining a step direction of the Perturb and Observe Maximum Power Point Tracking method using the present rotational frequency of the electric motor.

4. The method according to claim 3, further comprising:

generating a DC current by the photovoltaic array;

inverting the DC current into an AC current by the inverter; and

supplying the electric motor with the AC current.

5. A method for tracking a maximum power point of a photovoltaic array driving an electric motor through an inverter, comprising:

detecting a present rotational frequency of the electric motor from a frequency of an AC current supplied from the inverter to the electric motor using a frequency setpoint of the inverter to detect the present rotational frequency from the frequency of the AC current supplied from the inverter to the electric motor;

performing a Perturb and Observe Maximum Power Point Tracking method to track the maximum power point of the photovoltaic array; and

determining a step direction of the Perturb and Observe Maximum Power Point Tracking method using the present rotational frequency of the electric motor.

6. The method according to claim 5, further comprising:

generating a DC current by the photovoltaic array;

inverting the DC current into the AC current by the inverter; and

supplying the electric motor with the AC current.