CN-122001198-A - Current sharing control method of power conversion device and power converter

CN122001198ACN 122001198 ACN122001198 ACN 122001198ACN-122001198-A

Abstract

The application relates to a current sharing control method of a power conversion device and a power converter, wherein the current sharing control method is used for obtaining the current average apparent power of a plurality of parallel power converters, the instantaneous current, the instantaneous voltage and the instantaneous angular frequency of a first power converter; the method comprises the steps of determining composite virtual impedance according to current average apparent power, generating DQ axis voltage regulating signals based on the composite virtual impedance, instantaneous current DQ axis components and instantaneous voltage angular frequency, and generating output driving signals according to the DQ axis voltage regulating signals, the instantaneous voltage DQ axis components, the instantaneous current DQ axis components and preset voltage reference values. The corresponding reactance in the output impedance of the power converters is counteracted by the respective composite virtual impedance of the parallel power converters of the current average apparent power regulation parallel system of the power converters, so that the output impedance of the power converters is more close to the resistance, and the load sections meet the industry standard of uniform flow.

Inventors

LI JI
HUANG WEI
WANG LEI
CHEN XI

Assignees

深圳市正浩创新科技股份有限公司

Dates

Publication Date: 20260508
Application Date: 20250613

Claims (10)

1. A current sharing control method of a power converter, applied to a first power converter in a plurality of parallel power converters, the method comprising: Acquiring current average apparent power of the plurality of parallel power converters, instantaneous output current of the first power converter, instantaneous output voltage and instantaneous voltage angular frequency; Obtaining an instantaneous current DQ axis component and an instantaneous voltage DQ axis component according to the instantaneous output current and the instantaneous output voltage; Determining a composite virtual impedance according to the current average apparent power; generating a DQ axis voltage adjustment signal based on the complex virtual impedance and the instantaneous current DQ axis component, the instantaneous voltage angular frequency; And generating an output driving signal according to the DQ axis voltage regulating signal, the instantaneous voltage DQ axis component, the instantaneous current DQ axis component and a preset voltage reference value, wherein the driving signal is used for driving the power converter to output alternating current.
2. The method of claim 1, wherein said determining a composite virtual impedance from said current average apparent power comprises: and determining the composite virtual impedance according to the current average apparent power and the mapping relation between the load power of the first power converter and the composite virtual impedance, wherein in the mapping relation, the composite virtual impedance and the load power form a negative correlation relation.
3. The method of claim 1, wherein the composite virtual impedance comprises a virtual resistive impedance and a virtual inductive impedance, the determining the composite virtual impedance from the current average apparent power preceded by: And determining the amplitude modulation range of the virtual resistive impedance and the amplitude modulation range of the virtual inductive impedance according to the mapping relation between the load power of the first power converter and the composite virtual impedance, wherein the virtual resistive impedance and the load power form a negative correlation in the amplitude modulation range of the virtual resistive impedance, and the virtual inductive impedance and the load power form a negative correlation in the amplitude modulation range of the virtual inductive impedance.
4. A method according to claim 3, wherein said determining the amplitude modulation range of the virtual resistive impedance and the amplitude modulation range of the virtual inductive impedance from the mapping of the load power of the first power converter to the complex virtual impedance comprises: Determining an upper limit value of the virtual resistive impedance and an upper limit value of the virtual inductive impedance under the condition that the first power converter is empty based on the mapping relation; Determining a lower limit value of the virtual resistive impedance and a lower limit value of the virtual inductive impedance under a condition that the first power converter is fully loaded based on the mapping relation; And determining the amplitude modulation range of the virtual inductive impedance according to the upper limit value and the lower limit value of the virtual resistive impedance.
5. The method of claim 4, wherein said determining a composite virtual impedance from said current average apparent power comprises: When the current average apparent power is larger than a first preset power, determining that the virtual resistive impedance in the composite virtual impedance is a lower limit value in an amplitude modulation range of the virtual resistive impedance, and determining that the virtual inductive impedance in the composite virtual impedance is a lower limit value in the amplitude modulation range of the virtual inductive impedance; when the current average apparent power is smaller than a second preset power, determining that the virtual resistive impedance in the composite virtual impedance is an upper limit value in an amplitude modulation range of the virtual resistive impedance, and determining that the virtual inductive impedance in the composite virtual impedance is an upper limit value in the amplitude modulation range of the virtual inductive impedance; and when the current average apparent power is not smaller than a second preset power and not larger than a first preset power, the virtual resistive impedance and the virtual inductive impedance in the composite virtual impedance are in negative correlation with the current average apparent power.
6. The method of any of claims 1-5, wherein the transient current DQ axis component comprises a transient current D axis component and a transient current Q axis component, the composite virtual impedance comprises a virtual resistive impedance and a virtual inductive impedance, and the generating the DQ axis voltage adjustment signal based on the composite virtual impedance and the transient current DQ axis component, the transient voltage angular frequency comprises: Generating a first D-axis voltage adjustment amount from the virtual resistive impedance and the instantaneous current D-axis component; generating a second D-axis voltage adjustment amount according to the virtual inductive impedance, the instantaneous current Q-axis component, and the instantaneous voltage angular frequency; generating a first Q-axis voltage adjustment based on the virtual resistive impedance and the instantaneous current Q-axis component; and generating a second Q-axis voltage adjustment amount according to the virtual inductive impedance, the instantaneous current D-axis component and the instantaneous voltage angular frequency.
7. The method of claim 6, wherein the transient voltage DQ axis component comprises a transient voltage D axis component and a transient voltage Q axis component, wherein the preset voltage reference value comprises a Q axis voltage reference value and a droop control strategy based D axis voltage reference value, wherein the generating the output drive signal based on the DQ axis voltage adjustment signal, the transient voltage DQ axis component, the transient current DQ axis component, and the preset voltage reference value comprises: Generating a D-axis modulation voltage according to the first D-axis voltage adjustment amount, the second D-axis voltage adjustment amount, the instantaneous voltage D-axis component, the instantaneous current D-axis component and the D-axis voltage reference value; Generating a Q-axis modulation voltage according to the first Q-axis voltage adjustment amount, the second Q-axis voltage adjustment amount, the instantaneous voltage Q-axis component, the instantaneous current Q-axis component, and the Q-axis voltage reference value; the driving signal is generated according to the D-axis modulation voltage and the Q-axis modulation voltage.
8. The method of claim 1, wherein the D-axis voltage reference determined based on the droop control strategy comprises: and obtaining the D-axis voltage reference value according to the droop voltage and the rated output voltage determined by the droop control strategy.
9. The power converter is characterized by comprising a power conversion circuit and a controller connected with the power conversion circuit, wherein the controller is used for executing the current sharing control method of the power conversion device according to any one of claims 1-8 when the power converter is connected with other power converters in parallel.
10. A parallel power converter system comprising a plurality of parallel power converters, any one of the power converters comprising a power conversion circuit and a controller connected to the power conversion circuit, wherein the controller is configured to perform the current sharing control method of the power conversion device according to any one of claims 1 to 8.

Description

Current sharing control method of power conversion device and power converter Technical Field The application belongs to the technical field of power electronics, and particularly relates to a current sharing control method of a power conversion device, a power converter and a power converter parallel operation system. Background The current equalizing characteristic of the parallel inverter has great influence on the overload capacity and the overall efficiency (circulation) of the system. The uneven flow between the inverters can reduce the stability of the system and the service life. In some scenarios, parallel inverter full load segment non-uniformity flow is required to be <5%. Droop control is a typical representative of communication-free current sharing, and is widely applied by virtue of simplicity and easiness in use. Droop control can be classified into inductive droop control and resistive droop control according to the difference in the output line impedance of the inverter. The output resistance of the common low-voltage micro-grid inverter is far greater than the sensitivity, so that resistive droop control is adopted for current sharing. However, since the inverter is not completely resistive in its actual impedance, it has some inductance, and the inductance varies with the size of the load. Therefore, it is difficult to ensure that the parallel inverters meet the current sharing requirement in the full load section and various load scenes by only relying on the traditional resistive droop. Disclosure of Invention The application aims to provide a current sharing control method, a power converter and a power converter parallel operation system, which aim to solve the problem that parallel output of an inverter is difficult to meet current sharing requirements under traditional resistive droop control. In a first aspect, an embodiment of the present application provides a current sharing control method of a power converter, which is applied to a first power converter in a plurality of parallel power converters, and the method includes: Acquiring current average apparent power of the plurality of parallel power converters, instantaneous output current of the first power converter, instantaneous output voltage and instantaneous voltage angular frequency; Obtaining an instantaneous current DQ axis component and an instantaneous voltage DQ axis component according to the instantaneous output current and the instantaneous output voltage; Determining a composite virtual impedance according to the current average apparent power; generating a DQ axis voltage adjustment signal based on the complex virtual impedance and the instantaneous current DQ axis component, the instantaneous voltage angular frequency; And generating an output driving signal according to the DQ axis voltage regulating signal, the instantaneous voltage DQ axis component, the instantaneous current DQ axis component and a preset voltage reference value, wherein the driving signal is used for driving the power converter to output alternating current. In some embodiments, the determining a composite virtual impedance from the current average apparent power comprises: and determining the composite virtual impedance according to the current average apparent power and the mapping relation between the load power of the first power converter and the composite virtual impedance, wherein in the mapping relation, the composite virtual impedance and the load power form a negative correlation relation. In some embodiments, the composite virtual impedance comprises a virtual resistive impedance and a virtual inductive impedance, the composite virtual impedance preceding the current average apparent power according to the current average apparent power comprising: And determining the amplitude modulation range of the virtual resistive impedance and the amplitude modulation range of the virtual inductive impedance according to the mapping relation between the load power of the first power converter and the composite virtual impedance, wherein the virtual resistive impedance and the load power form a negative correlation in the amplitude modulation range of the virtual resistive impedance, and the virtual inductive impedance and the load power form a negative correlation in the amplitude modulation range of the virtual inductive impedance. In some embodiments, the determining the amplitude modulation range of the virtual resistive impedance and the amplitude modulation range of the virtual inductive impedance according to the mapping relation between the load power of the first power converter and the composite virtual impedance includes: Determining an upper limit value of the virtual resistive impedance and an upper limit value of the virtual inductive impedance under the condition that the first power converter is empty based on the mapping relation; Determining a lower limit value of the virtual resistive impedance and a lower limit value of