BI-DIRECTIONAL ENERGY CONVERTER WITH MULTIPLE DC SOURCES

• US 20150357940A1
• Filed: 05/29/2015
• Published: 12/10/2015
• Est. Priority Date: 12/16/2011
• Status: Active Grant

• Current Assignee: Sungrow Power Supply Co., Ltd.
• Original Assignee: Empower Micro Incorporated
• Inventors: Ilic, Milan, Nuotio, Mika, Bonanno, Jon
• Granted Patent: US 10,707,782 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems
• CPC Class Codes: H02M 1/0077 Plural converter units whose outputs are connected in series
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H02M 7/125 Avoiding or suppressing excessive transient voltages or currents
• CPC Class Codes: H02M 7/49 Combination of the output voltage waveforms of a plurality of converters
• CPC Class Codes: H02M 7/5387 in a bridge configuration
• CPC Class Codes: H02M 7/72 using discharge tubes with control electrode or semiconductor devices with control electrode

Abstract

A multiple dc sources bi-directional energy converter includes a plurality of direct current (DC) power sources; one alternating current (AC) power source; at least one stacked alternating current (AC) phase, each stacked alternating current (AC) phase having at least two or more full bridge converters, each respectively coupled to one of the direct current power sources, each full bridge converter having an inductor electrically coupled thereto; and a local controller coupled to each full bridge converter controlling the firing sequence of the switching devices in said full bridge converter to generate an approximately nearly sinusoidal voltage waveform when operated as a voltage source inverter in one direction or generate an approximately nearly constant direct current (DC) output when operated as a full-wave active rectifier in the opposite direction.

Claims

1. A multiple dc sources bi-directional energy converter, comprising:

a plurality of direct current (DC) power sources;

one alternating current (AC) power source;

at least two or more full bridge converters, each having a primary node and a secondary node, each full bridge converter having a positive and negative node, each full bridge converter having a voltage supporting device electrically connected in a parallel relationship between said positive node and said negative node, each full bridge converter having an inductor electrically connected between primary and said first leg of full bridge converter, and a direct current (DC) power source connected between said positive and negative nodes;

at least one stacked alternating current (AC) phase, each stacked alternating current (AC) phase having a plurality of said full bridge converters, each of said full bridge converters in each stacked alternating current (AC) phase interconnected in a series relationship with said secondary node of one of said full bridge converters connected to said primary node of another full bridge converter, said series interconnection defining a first full bridge converter and a last full bridge converter, each alternating current (AC) phase having an input node at said primary node of said first full bridge converter and an output node at said secondary node of said last full bridge converter;

an alternative current (AC) power source connected across said alternating current (AC) phase;

a local controller coupled to each full bridge converter controlling the firing sequence of the switching devices in said full bridge converter to generate an approximate sinusoidal voltage waveform when operated as a voltage source inverter in one direction or generate an approximate constant direct current (DC) output when operated as a full-wave active rectifier in the opposite direction; and

a system controller communicating to each local controller, the system level controller generating a system control signal for configuration activation, deactivation and operating mode selection of said local controller.

2. The bi-directional energy converter of claim 1, comprising three stacked inverter phases.

3. The bi-directional energy converter of claim 2, comprising a wye (Y) connection or a delta (Δ

) connection.

4. The bi-directional energy converter of claim 1, comprising

a two pole switch;

a motor coupled to the first pole of the switch; and

an AC power source coupled to the second pole of the switch.

5. The bi-directional energy converter of claim 4, comprising a controller connecting stacked output phase to AC power source to charge a DC source or to provide driving power to an electrical motor.

6. The bi-directional energy converter of claim 1, wherein each full bridge converter incorporates a switch electrically connected in parallel to its primary and secondary node, where said switch can be controlled by the local controller associated with said full bridge converter or by the system controller to short the primary and secondary nodes, allowing the remaining series connected full bridge converters to operate.

7. The bi-directional energy converter of claim 1, wherein each full bridge converter comprises a first switching pair and a second switching pair, each of said switching pairs having a plurality of switching means for controllably regulating electrical current flow.

8. The bi-directional energy converter of claim 7, comprising a capacitor attached across said primary node and said secondary node.

9. The bi-directional energy converter of claim 7, wherein said switching means comprises a gate turn-off device and an anti-parallel device connected in parallel and oppositely biased with respect to one another.

10. The bi-directional energy converter of claim 9, wherein said gate turn-off device comprises a component selected from the group consisting of:

a gate turn-off thyristor, an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET), a metal semiconductor field effect transistor (MESFET), a junction gate field-effect transistor (JFET), a MOSFET controlled thyristor, a bipolar junction transistor (BJT), a static induction transistor, a static induction thyristor and a MOSFET turn-off thyristor.

11. The bi-directional energy converter of claim 9, wherein the antiparallel device is a diode.

12. The bi-directional energy converter of claim 1, comprising a buck or boost voltage regulation circuit between the direct current DC power source and the full bridge converter.

13. The bi-directional energy converter of claim 1, comprising a variable number of full bridge converters for configuration within a given or across different alternating current (AC) phase voltages.

14. The bi-directional energy converter of claim 1, where each stacked full bridge converter operates with different power.

15. The bi-directional energy converter of claim 1, comprising a variable number of stacked full bridge converters for each alternating current (AC) phase.

16. The bi-directional energy converter of claim 1 where dc power source can be any device that can store energy and supply energy such as any battery, capacitor or flying wheel.

17. The bi-directional energy converter of claim 1, where the positive and negative nodes of each full bridge converter is connected to one or more direct current (DC) battery cells, where the local controller of each said full bridge converter regulates the battery charge or discharge based on a defined charge and discharge profile, where such profiles can be static or dynamically determined by the system controller.

18. The bi-directional energy converter of claim 4, wherein the system controller drives a motor by having a master module to generate a reference frequency and other modules lock to the reference frequency.

19. The bi-directional energy converter of claim 4, wherein the system controller controls a motor by dynamically controlling power and drive reference frequency.

20. The bi-directional energy converter of claim 8, wherein each of said switching means having a first end and a second end, said first switching pair having a plurality of switching means electrically connected at said first end at said positive node of said full bridge inverter, said second end of one of said switching means of said first switching pair electrically connected to one end of an inductor-capacitor low pass filter and second end of the inductor-capacitor low pass filter is connected to said primary node, said second end of another of said switching means of said first switching pair electrically connected to said secondary node, said second switching pair having a plurality of switching means electrically connected at said second ends at said negative node of said full bridge inverter, said first end of one of said switching means of said second switching pair electrically connected to said primary node, said first end of another of said switching means of said second switching pair electrically connected to said secondary node.

21. A method for providing energy from one or more DC sources, comprising:

detecting grid AC voltage levels where a stacked phase is connected to a grid network;

calculating AC start up voltage for stacked full bridges;

generating a first error signal from said comparison of calculated power with a reference power and generate a reference DC current;

rectifying and averaging output AC current comparing said average output current level with a reference DC current;

generating a second error signal from said comparison of said average with said reference DC current level;

detecting an AC line voltage having a period;

generating a phase reference signal directly related to said period of said AC line voltage;

limiting phase reference signal per configuration limits provided by system controller determining a modulation index;

providing a reference table for said modulation index; and

generating a plurality of firing reference signals for a plurality of full bridge inverters using said phase reference signal and said sum of said phase shift offset signal and said average phase shift signal.