# US 11,121,619 B2 · Bus voltage secondary ripple suppression method and device

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- Number: US 11,121,619 B2
- Document ID: US11121619B2
- Status: Granted
- Kind: B2
- Application number: 16/898,913
- Filed: 2020-06-11
- Published: 2020-09-24
- Granted: 2021-09-14
- Earliest claimed: 2017-12-13
- Assignees: SMA Solar Technology AG
- Applicants: SMA Solar Technology AG
- Inventors: Chengwei Shu; Jiayu Yao; Shijun Li; Jin Cheng
- Web page: https://patentgrep.com/patent/US11121619B2

## CPC

- H02M 1/14: Arrangements for reducing ripples from DC input or output
- H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M 1/15: using active elements
- H02M 3/155: using semiconductor devices only
- H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators
- H02M 7/537: using semiconductor devices only, e.g. single switched pulse inverters
- H02M 1/0022: {the disturbance parameters being input voltage fluctuations}
- 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)

## Abstract

The disclosure discloses a bus voltage secondary ripple suppression method and a bus voltage secondary ripple suppression device. The method includes: determining a current working mode of an inverter Boost circuit; wherein the working mode includes a continuous current mode (CCM) and a discontinuous current mode (DCM); calculating an output compensation amount according to the current working mode of the inverter Boost circuit; superimposing the output compensation amount on a control output amount of the Boost circuit; and controlling the Boost circuit by a control output amount superimposed with an output compensation amount. According to the scheme of this embodiment, the third harmonic in the output current of the inverter is reduced, and the current output quality of the inverter is improved.

## Claims

### Claim 1

A bus voltage ripple suppression method for suppressing a ripple of a DC bus voltage of a two stage photovoltaic (PV) inverter structure having a Boost circuit, comprising:
determining a current working mode of the Boost circuit, wherein the current working mode comprises one of a continuous current mode (CCM) and a discontinuous current mode (DCM);
calculating an output compensation amount according to the determined current working mode of the Boost circuit;
superimposing the calculated output compensation amount on a control output amount of the Boost circuit; and
controlling the Boost circuit through the control output amount superimposed with the output compensation amount,
wherein determining the current working mode of the Boost circuit comprises:
determining that the Boost circuit is in the CCM mode when the direct current (DC) bus voltage (Udc) and a DC input PV voltage (Upv) of the Boost circuit meet: Udc*(1−D0=Upv;
determining that the Boost circuit is in the DCM mode when the DC bus voltage (Udc) and the DC input PV voltage (Upv) of the Boost circuit meet: Udc*(1−D0)>Upv; wherein D0 is a duty ratio of Pulse Width Modulation (PWM), and
wherein calculating the output compensation amount according to the current working mode of the Boost circuit comprises:
obtaining respectively a DC amount Udc of the DC bus voltage when there is no voltage fluctuation on a DC bus at an output of the Boost circuit and the DC bus voltage Udc=Udc + when there is voltage fluctuation on the DC bus;
obtaining a PWM compensation duty ratio from the obtained DC amount Udc of the DC bus voltage when there is no voltage fluctuation on the DC bus at an output of the Boost circuit, and the obtained DC bus voltage Udc when there is voltage fluctuation on the DC bus; and
using the PWM compensation duty ratio as an output compensation amount.

### Claim 2 (depends on 1)

The bus voltage ripple suppression method according to claim 1, wherein when there is no photovoltaic PV voltage fluctuation of the DC input PV voltage (Upv) of the boost circuit:
in the CCM mode a first PWM compensation duty ratio includes:
Δ
⁢
⁢
D
⁢
⁢
1
=
U
dc
-
U
dc
_
U
dc
*
(
1
-
D
0
)
wherein Udc=Udc+ is the DC bus voltage; Udc is a DC magnitude of the DC bus voltage; is the alternating current (AC) magnitude of the DC bus voltage; and ΔD1 is the first PWM compensation duty ratio.

### Claim 3 (depends on 1)

The bus voltage ripple suppression method according to claim 1, wherein when there is a PV voltage fluctuation of the DC input PV voltage (Upv) of the Boost circuit:
Upv=Upv+;
in the CCM mode a first PWM compensation duty ratio includes:
Δ
⁢
⁢
D
⁢
⁢
1
=
(
U
dc
-
U
dc
_
)
*
(
1
-
D
0
)
-
(
U
pv
-
U
pv
_
)
U
dc
;
wherein, Upv is a DC magnitude of the PV voltage; an AC magnitude of the PV voltage, Upv is the DC input photovoltaic (PV) voltage; Udc=Udc+ is the DC bus voltage; Udc is the DC amount of the DC bus voltage; is the alternating current (AC) amount of the DC bus voltage; ΔD1 is the first PWM compensation duty ratio.

### Claim 4 (depends on 1)

The bus voltage ripple suppression method according to claim 1, wherein when there is no DC input PV voltage fluctuation of the DC input photovoltaic (PV) voltage (Upv) of the boost circuit in the DCM mode a second PWM compensation duty ratio includes:
Δ
⁢
⁢
D
⁢
⁢
2
=
(
U
dc
-
U
dc
_
)
*
Upv
*
D
0
2
*
(
U
dc
_
-
U
pv
)
*
U
dc
;
wherein Upv is the DC input PV voltage; Udc=Udc+ is the DC bus voltage; Udc is the DC amount of the DC bus voltage; is the alternating current (AC) amount of the DC bus voltage; and ΔD2 is the second PWM compensation duty ratio.

### Claim 5 (depends on 1)

The bus voltage secondary ripple suppression method according to claim 1, wherein when there is the DC input PV voltage fluctuation of the DC input PV voltage (Upv) of the Boost circuit:
Upv=Upv+;
in the DCM mode a second PWM compensation duty ratio includes:
Δ
⁢
⁢
D
⁢
⁢
2
=
(
U
pv
_
2
*
(
U
dc
-
U
dc
_
)
-
U
dc
_
2
*
(
U
pv
-
U
pv
_
)
-
(
U
pv
-
U
pv
_
)
*
(
U
dc
-
U
dc
_
)
*
(
U
dc
_
-
U
pv
_
)
)
2
*
U
pv
*
U
dc
*
(
U
dc
_
-
U
pv
_
)
*
D
0
;
wherein Upv is the DC amount of the PV voltage; is an AC amount of the PV voltage Upv is the DC input PV voltage; Udc=Udc+ is the DC bus voltage; Udc is the DC amount of the DC bus voltage; is the alternating current (AC) amount of the DC bus voltage; ΔD2 is the second PWM compensation duty ratio.

### Claim 6 (depends on 1)

A bus voltage ripple suppression device; configured to suppress the ripple of the DC bus voltage (Udc) of a two-stage photovoltaic inverter structure having the Boost circuit by the method according to claim 1, the bus voltage ripple suppression device comprising: a determination module configured to determine a current working mode of the Boost circuit, wherein the current working mode comprises the continuous current mode (CCM) and the discontinuous current mode (DCM); a calculation module configured to calculate the output compensation amount according to the current working mode of the Boost circuit; a compensation module configured to superimpose the output compensation amount on the control output amount of the Boost circuit; and a control module configured to control the Boost circuit through the control output amount superimposed with the output compensation amount.