Voltage source inverter control for unbalanced and nonlinear loads

Patent metadata

Field	Value
Publication number	US-12374888-B1
Application number	US-202418415227-A
Country	US
Kind code	B1
Filing date	Jan 17, 2024
Priority date	Jan 17, 2024
Publication date	Jul 29, 2025
Grant date	Jul 29, 2025

Abstract

An interface circuit to interface an energy source to a power bus of a microgrid includes a switching inverter circuit, an output filter circuit coupled between an output of the three-phase inverter circuit and the power bus, and a control circuit loop to control switching of the switching inverter circuit. The control circuit loop is coupled to the output filter circuit and the switching inverter and includes a proportional-integral oscillator-based repetitive (PIOR) controller.

First claim

What is claimed is:

1. An interface circuit to interface an energy source to a power bus of a microgrid, the interface circuit comprising:
a switching inverter circuit;
an output filter circuit coupled between an output of the switching inverter circuit and the power bus; and
a first control circuit loop to control switching of the switching inverter circuit, wherein the first control circuit loop is coupled to the output filter circuit and the switching inverter and includes a proportional-integral oscillator-based repetitive (PIOR) controller, wherein the PIOR controller includes proportional-integral controller elements and oscillator-repetitive controller elements.

2. The interface circuit of claim 1 , including:
a second control circuit loop that is an inner control circuit loop and wherein the first control circuit loop is an outer control circuit loop;
wherein the inner control circuit loop is coupled to the output filter circuit and includes a proportional (P) controller; and
wherein the output filter includes an inductor and a capacitor, and inner control loop is coupled to the inductor and the output control loop is coupled to the capacitor.

3. The interface circuit of claim 1 , including:
a second control circuit loop that is an inner control circuit loop and wherein the first control circuit loop is an outer control circuit loop; and
wherein the inner control circuit loop is coupled to the output filter circuit and includes a proportional-integral (PI) controller; and
wherein the output filter includes an inductor and a capacitor, and inner control loop is coupled to the inductor and the output control loop is coupled to the capacitor.

4. The interface circuit of claim 1 , wherein the filter circuit includes at least one inductor, and the PIOR controller is configured to control the switching of the switching inverter circuit to regulate current of the inductor.

5. The interface circuit of claim 1 ,
wherein the switching inverter circuit is a three-phase switching inverter circuit; and
wherein the filter circuit is an LCL filter circuit.

6. The interface circuit of claim 1 , wherein a frequency response of the PIOR controller has a pole at a fundamental frequency of the microgrid and at harmonics of the fundamental frequencies, and a flat response at frequencies less than the fundamental frequency.

7. The interface circuit of claim 2 , wherein the PIOR controller is a stationary reference frame controller.

8. The interface circuit of claim 1 , wherein the PIOR controller is configured to compute a discrete time domain transfer function PIOR (z) to control switching of the switching inverter circuit, wherein

PIOR
⁡
(
z
)

=

(

k
p

+

k
i

⁢

T
s

z
-
1

)

·

[

(

π

ω
0

⁢

T
s

⁢

z
-
1

z
+
1

)

·

(

1
+

z

-
2

⁢
π

ω
0

⁢

T
s

1
-

z

-
2

⁢
π

ω
0

⁢

T
s

)

-
0.5

]

.

9. The interface circuit of claim 1 ,
wherein the inverter circuit is a three-phase inverter circuit that includes insulated gate bipolar transistors (IGBTs) and switching of the IGBTs is controlled using pulse width modulation (PWM) to convert a direct current (DC) input of the three-phase inverter circuit to an alternating current (AC) output of the three-phase inverter circuit; and
wherein the first control circuit loop provides

Assignees

• Caterpillar Inc

Inventors

• Illindala Mahesh Sitaram
• Sunkara Varsha
• Han Seok-Hee
• Wai Jackson
• Gerdes Jesse R
• Yu Dachuan

Classifications

• H02J2101/24

  Photovoltaics · CPC title

• H02J2101/28

  Wind energy · CPC title

• H02J2105/10

  Local stationary networks having a local or delimited stationary reach · CPC title

• H02J2101/30

  Fuel cells · CPC title

• H02M7/53873

  with digital control · CPC title