# US 2014/0192568 A1 · Inverter for a Distributed Power Generator

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- Number: US 2014/0192568 A1
- Document ID: US20140192568A1
- Status: Published application
- Kind: A1
- Application number: 14/173,439
- Filed: 2014-02-05
- Published: 2014-07-10
- Earliest claimed: 2009-02-20
- Assignees: Sparq Systems Inc.
- Applicants: SPARQ Systems Inc.
- Inventors: Ali Khajehoddin; Praveen K. Jain; Alireza Bakhshai
- Web page: https://patentgrep.com/patent/US20140192568A1

## CPC

- H02J 3/381: {Dispersed generators}
- G05F 1/67: to the maximum power available from a generator, e.g. from solar cell
- H02M 1/14: Arrangements for reducing ripples from DC input or output
- H02M 7/48: using discharge tubes with control electrode or semiconductor devices with control electrode
- H10F 77/955: {for photovoltaic devices}
- H02J 2101/24: Photovoltaics
- H02M 1/12: Arrangements for reducing harmonics from AC input or output
- Y02E 10/56: Power conversion systems, e.g. maximum power point trackers
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Provided is a maximum power point (MPP) tracker for a PV cell inverter, and a PV cell inverter. The MPP tracker decouples output power oscillations from the input power generation and extracts maximum available power from the PV cell. The PV cell inverter uses the MPP tracker and generates a sinusoidal output current from the MPP tracker output. The sinusoidal output current may be fed to a power distribution grid. The PV cell inverter may use a pulse width modulation technique to cancel harmonics in the sinusoidal output current. The circuits use a minimum number of components and avoid use of large electrolytic capacitors.

## Claims

### Claim at position 1

1-32. (canceled)

### Claim 33

A compensator, comprising:
an input that samples a voltage source inverter input voltage or a current source inverter input current;
a processor that modifies a pulse width modulation reference signal according to the voltage source inverter input voltage or the current source inverter input current; and
an output that provides the modified pulse width modulation reference signal to a pulse width modulator;
wherein the pulse width modulator controls the voltage source inverter or the current source inverter such that a harmonic in the voltage source inverter output current or current source inverter output current is substantially reduced;
wherein the harmonic arises from voltage source inverter input voltage oscillation or current source inverter input current oscillation.

### Claim 34 (depends on 33)

The compensator of claim 33, wherein the processor modifies the pulse width modulation reference signal in proportion to a ratio of average and instantaneous values of the voltage source inverter input voltage or the current source inverter input current.

### Claim 35 (depends on 33)

The compensator of claim 33, wherein:
the voltage source inverter output current or the current source inverter output current is connected to a power distribution grid having a grid frequency; and
wherein at least one harmonic that is substantially reduced is at a frequency that is twice the grid frequency.

### Claim 36 (depends on 33)

The compensator of claim 33, wherein the compensator is connected to a circuit comprising:
a high side input point and a low side input point for connection to a distributed power generator;
a parallel input capacitor connected across the high side input point and the low side input point; and
a first regulating circuit connected in parallel with the parallel input capacitor, the first regulating circuit having a high side output point connected to the voltage source inverter input so as to provide the voltage source inverter input voltage;
wherein the parallel input capacitor has a small value such that voltage source inverter input voltage oscillation is not substantially reduced.

### Claim 37 (depends on 36)

The compensator of claim 36, wherein the first regulating circuit comprises:
a switch connected between the high side input point and a node;
an output inductor connected between the node and the high side output point; and
a diode connected between the node and a low side output point.

### Claim 38 (depends on 36)

The compensator of claim 36, wherein the first regulating circuit regulates voltage across the parallel input capacitor between a lower limit and an upper limit;
wherein the upper limit is a reference voltage and the lower limit is selected so that a switching frequency of the switch and voltage oscillation across the parallel input capacitor do not exceed selected values.

### Claim 39 (depends on 38)

The compensator of claim 38, wherein the reference voltage is obtained from a maximum power point tracking (MPPT) algorithm.

### Claim 40 (depends on 33)

The compensator of claim 33, wherein the compensator is connected to a circuit comprising:
a high side input point and a low side input point for connection to a distributed power generator;
a series input inductor having a first terminal and a second terminal, the first terminal connected to one of the high side input point and the low side input point; and
a second regulating circuit connected between the second terminal of the series input inductor and the other of the high side input point and the low side input point, the second regulating circuit having a high side output point connected to the current source inverter input so as to provide the current source inverter input current;
wherein the series input inductor has a small value such that current source inverter input current oscillation is not substantially reduced.

### Claim 41 (depends on 40)

The compensator of claim 40, wherein the second regulating circuit comprises:
a switch connected between the second terminal of the series input inductor and the other of the high side input point and the low side input point; and
a diode connected in series between the second terminal of the series input inductor and a corresponding high side output point or low side output point.

### Claim 42 (depends on 40)

The compensator of claim 40, wherein the second regulating circuit regulates current through the series input inductor between a lower limit and an upper limit;
wherein the upper limit is a reference current and the lower limit is selected so that a switching frequency of the switch and current oscillation through the series input inductor do not exceed selected values.

### Claim 43 (depends on 42)

The compensator of claim 42, wherein the reference current is obtained from a maximum power point tracking (MPPT) algorithm.

### Claim 44 (depends on 36)

The compensator of claim 36, wherein the distributed power generator comprises a photovoltaic cell.

### Claim 45 (depends on 40)

The compensator of claim 40, wherein the distributed power generator comprises a photovoltaic cell.

### Claim 46

A method for controlling a voltage source inverter or a current source inverter, comprising:
sampling an input voltage of the voltage source inverter or an input current of the current source inverter;
modifying a pulse width modulation reference signal according to the voltage source inverter input voltage or the current source inverter input current; and
outputting the modified pulse width modulation reference signal to a pulse width modulator;
wherein the pulse width modulator controls the voltage source inverter or the current source inverter such that a harmonic in the voltage source inverter output current or current source inverter output current is substantially reduced;
wherein the harmonic arises from voltage source inverter input voltage oscillation or current source inverter input current oscillation.

### Claim 47 (depends on 46)

The method of claim 46, comprising modifying the pulse width modulation reference signal in proportion to a ratio of average and instantaneous values of the voltage source inverter input voltage or the current source inverter input current.

### Claim 48 (depends on 46)

The method of claim 46, comprising:
connecting the voltage source inverter output current or the current source inverter output current to a power distribution grid having a grid frequency; and
substantially reducing at least one harmonic at a frequency that is twice the grid frequency.

### Claim 49 (depends on 46)

The method of claim 46, further comprising:
using a first regulating circuit to provide the voltage source inverter input voltage, the first regulating circuit including:
a high side input point and a low side input point for connection to a distributed power generator; and
a parallel input capacitor connected across the high side input point and the low side input point; and
selecting a small value of the parallel input capacitor such that voltage source inverter input voltage oscillation is not substantially reduced.

### Claim 50 (depends on 49)

The method of claim 49, comprising:
operating the first regulating circuit to regulate voltage across the parallel input capacitor between a lower limit and an upper limit;
wherein the upper limit is a reference voltage; and
selecting the lower limit so that a switching frequency of a switch of the first regulating circuit and voltage oscillation across the parallel input capacitor do not exceed selected values.

### Claim 51 (depends on 50)

The method of claim 50, comprising obtaining the reference voltage from a maximum power point tracking (MPPT) algorithm.

### Claim 52 (depends on 46)

The method of claim 46, further comprising:
using a second regulating circuit to provide the current source inverter input current, the second regulating circuit including:
a high side input point and a low side input point for connection to a distributed power generator; and
a series input inductor connected in series with the high side input point or the low side input point; and
selecting a small value of the series input inductor such that current source inverter input current oscillation is not substantially reduced.

### Claim 53 (depends on 52)

The method of claim 52, comprising:
operating the second regulating circuit to regulate current through the series input inductor between a lower limit and an upper limit;
wherein the upper limit is a reference current; and
selecting the lower limit so that a switching frequency of a switch of the second regulating circuit and current oscillation through the series input inductor do not exceed selected values.

### Claim 54 (depends on 53)

The method of claim 53, comprising obtaining the reference current from a maximum power point tracking (MPPT) algorithm.

### Claim 55 (depends on 49)

The method of claim 49, wherein the distributed power generator comprises a photovoltaic cell.

### Claim 56 (depends on 52)

The method of claim 52, wherein the distributed power generator comprises a photovoltaic cell.