CN111934573B

CN111934573B - Current sharing control method and system

Info

Publication number: CN111934573B
Application number: CN202010688611.5A
Authority: CN
Inventors: 胡智勇; 陶旭东; 罗建鑫
Original assignee: Suzhou Weichuang Electrical Technology Co ltd
Current assignee: Suzhou Weichuang Electrical Technology Co ltd
Priority date: 2020-07-16
Filing date: 2020-07-16
Publication date: 2022-05-10
Anticipated expiration: 2040-07-16
Also published as: CN111934573A

Abstract

The application relates to a current sharing control method and a system, wherein the method comprises the following steps: acquiring a plurality of phase current instantaneous values corresponding to each inverter in the current period; obtaining expected voltage of the next period and voltage compensation values of all inverters according to a plurality of phase current instantaneous values corresponding to all the inverters, and obtaining input voltage vector values of all the inverters in the next period according to the expected voltage and the voltage compensation values of the next period; and controlling the corresponding inverter to work according to the input voltage vector value of the next period. The problem of non-uniform current caused by inconsistent current amplitude or phase of each inverter is solved; various risks caused by inconsistent temperature rise due to non-uniform current are reduced; the requirement of parallel operation of the inverters on the reactor is reduced.

Description

Current sharing control method and system

Technical Field

The present application relates to the field of electronic power technologies, and in particular, to a current sharing control method and system.

Background

The parallel operation of the inverters is an important way for improving the reliability of a power supply system and expanding the power supply capacity, and is widely applied to the fields of Uninterruptible Power Supply (UPS) power supply systems, photovoltaic power generation, wind power generation, motor driving and the like.

However, the driving signals are not uniform, the conduction voltage drops of the inverters are different, the output impedances are not uniform, and the load currents of the inverters are not uniform, and circulating currents are generated among the inverters.

In order to suppress such imbalance, a current equalizing reactor with a large inductance is generally connected in series at an output end, and the method of connecting the reactor in series can suppress high-frequency current such as current glitches, peaks, ripples and the like, but fundamental frequency and low-frequency current imbalance cannot be effectively suppressed, for example, effective current value imbalance cannot be suppressed, and long-time current effective value imbalance can cause faults such as inversion overheating of a load.

In order to make up for the defects of the series reactor, a method for adjusting the pulse width by using the difference value between the effective value of the phase current of each inverter and the average value of the effective values of the phase currents of all the inverters is also provided in the prior art, and the method solves the problem of uneven effective values to a certain extent. However, the scheme for adjusting the effective value has poor real-time performance, and the problem of inconsistent current phases cannot be solved.

Disclosure of Invention

In order to solve the technical problem of non-current sharing of the inverter, embodiments of the present application provide a current sharing control method and system.

In a first aspect, an embodiment of the present application provides a current sharing control method, where the method includes:

acquiring a plurality of phase current instantaneous values corresponding to each inverter in the current period;

obtaining expected voltage of the next period and voltage compensation values of all inverters according to a plurality of phase current instantaneous values corresponding to all the inverters, and obtaining input voltage of each inverter in the next period according to the expected voltage and the voltage compensation values of the next period;

and controlling the corresponding inverter to work according to the input voltage of the next period.

Optionally, obtaining an expected voltage of a next period and a voltage compensation value of each inverter according to a plurality of phase current instantaneous values corresponding to all the inverters, and obtaining an input voltage of each inverter in the next period according to the expected voltage and the voltage compensation value of the next period, includes:

respectively carrying out first processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter;

acquiring a current vector value of a target current;

and obtaining an expected voltage vector value of the next period and a voltage compensation value of each inverter according to the current vector values of all the inverters, and obtaining an input voltage vector value of each inverter in the next period according to the expected voltage vector value and the voltage compensation value of the next period.

Optionally, the first processing is performed on a plurality of phase current instantaneous values corresponding to each inverter respectively to obtain a target current in a target frequency band section of each inverter, and the method includes:

and respectively carrying out digital filtering processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter.

Optionally, obtaining a current vector value of the target current comprises:

acquiring a current coordinate system angle of each inverter in a current period;

and converting the target current from the current coordinate system to the target coordinate system through current coordinate transformation according to the angle of the current coordinate system to obtain a current vector value of the target current in the target coordinate system.

Optionally, when the current coordinate system is a three-phase stationary coordinate system and the target coordinate system is a two-phase orthogonal rotating coordinate system, the multiple phase current instantaneous values are multiple sets of three-phase instantaneous currents in the three-phase stationary coordinate system, and the target current is a three-phase current in the three-phase stationary coordinate system.

Optionally, each set of three-phase instantaneous currents includes a first instantaneous current, a second instantaneous current, and a third instantaneous current, and the target currents include a first target current, a second target current, and a third target current;

respectively carrying out digital filtering processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter, wherein the method comprises the following steps:

respectively carrying out digital filtering processing on all first instantaneous currents in a plurality of groups of three-phase instantaneous currents corresponding to each inverter to obtain a first target current of each inverter,

respectively carrying out digital filtering processing on all second instantaneous currents in the multiple groups of three-phase instantaneous currents corresponding to each inverter to obtain a second target current of each inverter,

and respectively carrying out digital filtering processing on all third instantaneous currents in the multiple groups of three-phase instantaneous currents corresponding to each inverter to obtain a third target current of each inverter.

Optionally, obtaining an expected voltage vector value of a next cycle and a voltage compensation value of each inverter according to the current vector values of all the inverters, and obtaining an input voltage vector value of each inverter of the next cycle according to the expected voltage vector value and the voltage compensation value of the next cycle includes:

obtaining an expected voltage vector value of the next period according to the current vector values of all the inverters;

acquiring a circulation vector difference value corresponding to each inverter according to the current vector values of all the inverters;

carrying out second processing on the circulating current vector difference value to obtain a voltage compensation value corresponding to each inverter;

and summing the voltage compensation value and the expected voltage vector value of the next period to obtain the input voltage vector value of the next period of each inverter.

Optionally, obtaining a circulating current vector difference value corresponding to each inverter according to the current vector values of all the inverters includes:

averaging the current vector values of all the inverters to obtain a current vector average value;

and taking the difference value of the current vector value of the inverter and the average value of the current vector as the circulating current vector difference value of the corresponding inverter.

Optionally, controlling the corresponding inverter to operate according to the input voltage of the next cycle, including:

and converting the input voltage vector value of the next period into a voltage driving signal, and sending the voltage driving signal to the corresponding inverter so as to control the corresponding inverter to work.

In a second aspect, an embodiment of the present application provides a current sharing control system, where the current sharing control system includes: the control device comprises a sampling module, a processing module and a driving module;

the sampling module is used for acquiring a plurality of phase current instantaneous values of each inverter in the current period;

the processing module is used for obtaining an expected voltage of a next period and a voltage compensation value of each inverter according to a plurality of phase current instantaneous values corresponding to all the inverters, and obtaining an input voltage vector value of each inverter in the next period according to the expected voltage and the voltage compensation value of the next period;

the driving module is used for controlling the corresponding inverter to work according to the input voltage of the next period.

Optionally, the processing module comprises: the current sharing control system comprises a first processing module, a current transformation module and a current sharing adjusting module;

the first processing module is used for respectively carrying out first processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter;

the current transformation module is used for acquiring a current vector value of the target current;

and the current-sharing adjusting module is used for obtaining an expected voltage vector value of the next period and a voltage compensation value of each inverter according to the current vector values of all the inverters, and obtaining an input voltage vector value of each inverter in the next period according to the expected voltage vector value and the voltage compensation value of the next period.

In a third aspect, embodiments of the present application provide a computer-readable storage medium, on which a computer program is stored, which, when executed by a processor, causes the processor to perform the steps of the method according to any one of the preceding claims.

In a fourth aspect, embodiments of the present application provide a computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor executing the program to perform the steps of the method according to any of the preceding claims.

Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:

according to the method, a plurality of phase current instantaneous values corresponding to each inverter in the current period are obtained; obtaining expected voltage of the next period and voltage compensation values of all inverters according to a plurality of phase current instantaneous values corresponding to all the inverters, and obtaining input voltage of each inverter in the next period according to the expected voltage and the voltage compensation values of the next period; and controlling the corresponding inverter to work according to the input voltage of the next period. The problem of non-uniform current caused by inconsistent current amplitude or phase of each inverter is solved, and unbalance of fundamental frequency and low-frequency current is effectively inhibited; various risks caused by inconsistent temperature rise of the inverter or overheating of the inverter with heavy load due to non-uniform current are reduced; the technical scheme of the application is good in real-time performance, the problem that current phases are inconsistent is effectively solved, and the requirement of parallel operation on the reactor is lowered; the inverter can be applied to a system for supplying power and generating power in parallel by two or more inverters. And each parallel inverter can realize rapid current sharing within ms-level time under various simulation working conditions of manual independent arrangement of cables with different lengths, insertion of different dead zones, different heat dissipation environments and the like.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.

Fig. 1 is an application scenario diagram of a current sharing control method in an embodiment;

FIG. 2 is a flow chart illustrating a current sharing control method according to an embodiment;

FIG. 3 is a schematic diagram of PWM modulation according to one embodiment;

FIG. 4 is a graph of an unprocessed sampled current waveform in one embodiment;

FIG. 5 is a graph of current waveforms after a first process in one embodiment;

FIG. 6 is a three-phase voltage time domain expression;

FIG. 7 is a schematic diagram of spatial positions of three-phase voltages;

FIG. 8 is a three-phase voltage vector diagram;

FIG. 9 is a waveform diagram of three phase voltages;

FIG. 10 is a schematic diagram of a three-phase stationary coordinate system and a two-phase orthogonal rotating coordinate system;

FIG. 11 is a block diagram of a current share control system in one embodiment;

fig. 12 is a block diagram of a current sharing control system in another embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Fig. 1 is an application scenario diagram of a current sharing control method in an embodiment; referring to fig. 1, the current sharing control method is applied to a current sharing control system. The current-sharing control system comprises a control device 100 and a plurality of inverters connected with the control device 100, the inverters form an inverter group 200, and the inverter group 200 comprises an inverter 201 and an inverter 202. The control device 100 executes the steps of acquiring a plurality of phase current instantaneous values corresponding to each inverter in the current period; obtaining expected voltage of the next period and voltage compensation values of all inverters according to a plurality of phase current instantaneous values corresponding to all the inverters, and obtaining input voltage of each inverter in the next period according to the expected voltage and the voltage compensation values of the next period; and controlling the corresponding inverter to work according to the input voltage of the next period.

FIG. 2 is a flow chart illustrating a current sharing control method according to an embodiment; referring to fig. 2, the current sharing control method includes the following steps:

s100: and acquiring a plurality of phase current instantaneous values corresponding to each inverter in the current period.

In particular, phase current transients may be sampled for each inverter by an oversampling technique. During a cycle, there are multiple phase current transients associated with each inverter. The sampling of each inverter is not interfered with each other.

Wherein, a period specifically refers to a control period.

S200: and obtaining the expected voltage of the next period and the voltage compensation value of each inverter according to the plurality of phase current instantaneous values corresponding to all the inverters, and obtaining the input voltage of each inverter in the next period according to the expected voltage and the voltage compensation value of the next period.

S300: and controlling the corresponding inverter to work according to the input voltage of the next period.

Specifically, the next cycle specifically refers to the next control cycle.

According to the phase current instantaneous values of all the inverters sampled in the current period, the expected voltage of the next period and the voltage compensation value of each inverter can be obtained, the expected voltage of the next period refers to the expected state of all the inverters in the next period, and the voltage compensation value refers to the voltage difference value from the current period state to the expected state of each inverter.

According to the expected voltage of the next period and the voltage compensation value of each inverter, the input voltage of each inverter in the next period can be obtained, which is equivalent to forming a feedback mechanism. And acquiring the input voltage of the next period by using the phase current instantaneous value of the current period, wherein the input voltage of the next period is the control signal of the next period of the inverter. The input voltage of the next period of each inverter is determined by the instantaneous values of the phase currents of the last period of all the inverters, and the input voltage of the next period is the result of current equalization.

The control device 100 controls the corresponding inverter to operate in the next period according to the input voltage of the next period corresponding to each inverter generated after current sharing.

In a specific embodiment, the driving module corresponding to the inverter receives an input voltage corresponding to a next period, and converts the input voltage of the next period into a voltage driving signal, and the driving module controls the corresponding inverter to operate according to the voltage driving signal.

In a specific embodiment, step S200 specifically includes the following steps:

respectively carrying out first processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter; acquiring a current vector value of a target current; and obtaining an expected voltage vector value of the next period and a voltage compensation value of each inverter according to the current vector values of all the inverters, and obtaining an input voltage vector value of each inverter in the next period according to the expected voltage vector value and the voltage compensation value of the next period.

Specifically, the first process may be a digital filtering process. And respectively carrying out digital filtering processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter.

FIG. 3 is a schematic diagram of PWM modulation according to one embodiment. Referring to fig. 3, a basic theoretical basis of a voltage modulation method commonly used in variable frequency motor control, power supply, and the like in the prior art is as follows: the narrow pulses with equal impulse but different shapes are applied to the links with inertia, and the effect is basically the same. The realization mode is as follows: the on-off of the switching device of the inverter circuit is controlled, so that a series of pulses with equal amplitude and variable width are obtained from the output, and the series of high-frequency pulse waves can be equivalent to required sine-wave voltage. Referring to fig. 3, the sine wave and the PWM wave in fig. 3 may be equivalent according to the high frequency area equivalent principle (width instead of height).

The actual inverter system is a sine wave equivalent to high-frequency pwm (pulse Width modulation) pulse Width modulation, and a sampling noise is added, and although the motor is originally an inductive load and a filter inductor is added (the inductor current cannot change suddenly), the current actually sampled is a mixed current obtained by a fundamental wave current (sine wave) + harmonic current + sampling glitch at the fundamental frequency shown in fig. 3, and the waveform of the mixed current is not smooth and is mixed with many glitches as shown in fig. 4. Sampling glitches can be filtered by a first process (for example, a digital filtering process), the current waveform after the first process is as shown in fig. 5, and the target frequency band interval is a frequency band around the fundamental frequency. The fundamental frequency is the output frequency of the inverter.

The nearby frequency band is associated with the fundamental frequency. The digital filtering process can adopt low-pass filtering or band-pass filtering, the cut-off frequency of the filtering can be dozens of times to dozens of times of the fundamental wave frequency, signals smaller than the cut-off frequency can pass through, and signals larger than the cut-off frequency can be basically filtered. The cutoff frequency of the filtering is selected comprehensively, and the cutoff frequency is neither too high so as not to well filter burrs and harmonic waves, nor too low, otherwise, amplitude and phase deviation can be caused.

And when the first processing is digital filtering processing, the plurality of phase current instantaneous values corresponding to each inverter are respectively processed through the digital filtering processing to filter high-frequency waves, so that the target current of each inverter target frequency band section is obtained.

Each phase current transient may be one of a single phase current transient, a two phase current transient, a three phase current transient, and a multi-phase current transient (multi-phase is greater than three phase). The target current obtained after the digital filtering processing is carried out on the plurality of phase current instantaneous values corresponding to each inverter has the same phase as the phase current instantaneous values before the processing.

The target currents of different phases are conveniently calculated by uniformly converting the current vector values.

The current vector values of all the inverters are participated in the calculation of the input voltage vector value of the next period, specifically, the expected voltage vector value of the next period and the voltage compensation value of each inverter are obtained according to the current vector values of all the inverters, so that the input voltage vector value of the next period of each inverter is calculated from the current vector values obtained by the previous period of all the inverters, and current sharing is realized.

In one embodiment, obtaining a current vector value for a target current comprises:

acquiring a current coordinate system angle of each inverter in a current period; and converting the target current from the current coordinate system to the target coordinate system through current coordinate transformation according to the angle of the current coordinate system to obtain a current vector value of the target current in the target coordinate system.

Specifically, the target current is a current in a current coordinate system, the current coordinate system angle of the inverter in the current period is an angle relationship between the current coordinate system where the target current of the inverter is located and the target coordinate system to be converted, and the target current can be mapped to the target coordinate system to be converted according to the target current and the current coordinate system angle to obtain a current vector value of the inverter.

For example: the current coordinate system may be one of a multi-phase stationary coordinate system, a three-phase stationary coordinate system, and a two-phase rectangular stationary coordinate system, and the target coordinate system may be a two-phase orthogonal rotational coordinate system.

In one embodiment, when the current coordinate system is a three-phase stationary coordinate system and the target coordinate system is a two-phase orthogonal rotating coordinate system, the plurality of phase current instantaneous values are a plurality of sets of three-phase instantaneous currents in the three-phase stationary coordinate system, and the target current is a three-phase current in the three-phase stationary coordinate system.

Specifically, the current coordinate system of the target current is a three-phase stationary coordinate system. The voltage output by the frequency converter is three-phase voltage, and similarly, the phase current instantaneous value of the frequency converter is three-phase current. The three-phase currents are spatially 120 degrees different from each other and temporally 120 degrees different from each other.

In modern motor control, three-phase currents with 120-degree spatial difference and 120-degree temporal difference are generally represented by a vector. At any time, the spatial relation of the output current is fixed (the structure is fixed), the waveform of the output current has a certain relation, and the relation can be uniformly expressed by the amplitude and the angle of the vector current. The formula expression of the three-phase current is specifically shown in fig. 6. The spatial relationship of the three-phase currents is shown in fig. 7, the vector relationship of the three-phase currents is shown in fig. 8, and the waveform diagram of the three-phase currents is shown in fig. 9.

Referring to fig. 6 and 9, at any time, as long as the amplitude of the voltage vector and the current angle 2 pi ft are obtained, the respective instantaneous values of the three-phase currents can be obtained.

In a specific embodiment, the target current is converted from the current coordinate system to the target coordinate system through current coordinate transformation according to the current coordinate system angle, and a current vector value of the target current in the target coordinate system is obtained.

Specifically, the current coordinate transformation refers to converting a current vector in one coordinate system from one coordinate system to another coordinate system.

There are many conversion modes for the current coordinate transformation, and the current coordinate transformation in the embodiment of the present application is to transform the current from a three-phase stationary coordinate system to a two-phase orthogonal rotating coordinate system, which is also called Park transformation. Referring to fig. 10, the current vector Is can be projected (equivalently transformed) onto a three-phase stationary coordinate system shown consisting of Ia, Ib, Ic, where Ia, Ib, Ic are 120 degrees from each other; it can also be projected onto a two-phase orthogonal rotating coordinate system shown consisting of Id, Iq, where Id, Iq are orthogonal. The principle of the voltage vector and the current vector is the same. In the embodiment of the application, a current vector Is under a three-phase static coordinate system Is converted into a two-phase orthogonal rotating coordinate from the three-phase static coordinate system to obtain a corresponding current vector value, and the current vector value consists of Id and Iq.

The core purpose of the current coordinate transformation is to transform sinusoidal three-phase static alternating current into rotary two-phase orthogonal direct current, so that decoupling and control are facilitated. The three-phase ac voltage is converted into the two-phase dc voltage to prepare for the subsequent calculation of the next-beat voltage output value, because the calculation of the next-beat voltage is generally based on the calculation in the two-phase rotating coordinate system in the three-phase ac motor control. Wherein the next beat is the next period or the next control period.

In a specific embodiment, each set of three-phase instantaneous currents comprises a first instantaneous current, a second instantaneous current and a third instantaneous current, and the target currents comprise a first target current, a second target current and a third target current.

Respectively carrying out first processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter, and specifically comprising the following steps:

Specifically, a reference table of three-phase instantaneous current versus target current such as shown in the following table

Table 1: reference table for relation between three-phase instantaneous current and target current

	First instantaneous current	Second instantaneous current	Third instantaneous current
				Group
1	Ia1	Ib1	Ic1
				Group 2	Ia2	Ib2	Ic2
Group
	3	Ia3	Ib3	Ic3
Group 4					Ia4	Ib4	Ic4
	Group
5		Ia5	Ib5	Ic5
	Group 6				Ia6	Ib6	Ic6
Group 7		Ia7	Ib7	Ic7
	Group 8				Ia8	Ib8	Ic8
Group 9		Ia9	Ib9	Ic9
	Group
10		Ia10	Ib10	Ic10
	Target current				Ia	Ib	Ic

Table 1 is a reference table of the relationship between the instantaneous value of the phase current and the target current of an inverter in a specific embodiment. The inverter corresponds to 10 groups of three-phase instantaneous currents, and each group of three-phase instantaneous currents comprises a first instantaneous current, a second instantaneous current and a third instantaneous current. All first instantaneous currents Ia1-Ia10 in the 1 st to 10 th groups of three-phase instantaneous currents are subjected to digital filtering processing to obtain a first target current Ia of the inverter; all second instantaneous currents Ib1-Ib10 in the 1 st to 10 th groups of three-phase instantaneous currents are subjected to digital filtering processing to obtain second target currents Ib of the inverter; and performing digital filtering processing on all the third instantaneous currents Ic1-Ic10 in the three-phase instantaneous currents of the groups 1-10 to obtain a third target current Ic of the inverter. The first target current Ia, the second target current Ib, and the third target current Ic constitute a target current of the inverter. The target current of the inverter is also a three-phase current.

The three-phase instantaneous currents Ia1-Ia10, Ib1-Ib10 and Ic1-Ic10 of the inverter are collected without interference. Table 1 is merely a reference table of relation between three-phase instantaneous currents of inverters and target currents, and in a specific practical operation, three-phase instantaneous currents collected by each inverter are not limited to 10 groups.

Specifically, the first instantaneous current is an A-phase instantaneous current, the second instantaneous current is a B-phase instantaneous current, the third instantaneous current is a C-phase instantaneous current, and each set of three-phase instantaneous currents comprises an A-phase instantaneous current, a B-phase instantaneous current and a C-phase instantaneous current. Since each single inverter corresponds to a plurality of sets of three-phase instantaneous currents, the single inverter corresponds to a plurality of a-phase instantaneous currents, a plurality of B-phase instantaneous currents, and a plurality of C-phase instantaneous currents.

Similarly, the first target current is an a-phase target current, the second target current is a B-phase target current, and the third target current is a C-phase target current. The target currents corresponding to the single inverter include an a-phase target current, a B-phase target current, and a C-phase target current.

In a specific embodiment, obtaining an expected voltage vector value of a next cycle and a voltage compensation value of each inverter according to current vector values of all inverters, and obtaining an input voltage vector value of each inverter of the next cycle according to the expected voltage vector value and the voltage compensation value of the next cycle specifically includes: obtaining an expected voltage vector value of the next period according to the current vector values of all the inverters; acquiring a circulation vector difference value corresponding to each inverter according to the current vector values of all the inverters; carrying out second processing on the circulating current vector difference value to obtain a voltage compensation value corresponding to each inverter; and summing the voltage compensation value and the expected voltage vector value of the next period to obtain the input voltage vector value of the next period of each inverter.

In particular, different control objects, voltage and current, have an inherent relationship, i.e. applying a voltage will produce a corresponding current, and similarly, a desired voltage can be obtained based on the current and a desired state. In the embodiment of the application, the current vector of each inverter is known, and the expected voltage vector value of the next period which is the same for all the inverters can be obtained according to the current vectors of all the inverters.

The method for specifically acquiring the circulating current vector difference value corresponding to the inverter specifically comprises the following steps: averaging the current vector values of all inverters to obtain a current vector average value; and taking the difference value of the current vector value of the inverter and the average value of the current vector as the circulating current vector difference value of the corresponding inverter.

And performing second processing on the circulating current vector difference value to obtain a voltage compensation value corresponding to each inverter, wherein the second processing specifically comprises the following steps: and inputting the circulating current vector difference value into a PI controller, and obtaining an output value as a voltage compensation value of the corresponding inverter through proportional regulation and integral regulation.

In a specific embodiment, step S300 specifically includes: and converting the input voltage vector value of the next period into a voltage driving signal, and sending the voltage driving signal to the corresponding inverter so as to control the corresponding inverter to work.

Specifically, the input voltage vector value of the next period is sent to the driving module corresponding to the corresponding inverter, the driving module obtains a voltage driving signal according to the input voltage vector value of the next period, and the voltage driving signal is sent to the corresponding inverter to control the inverter to work.

It should be understood that, although the steps in the flowchart of fig. 2 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in fig. 2 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

In one embodiment, the present application provides a current share control system, referring to fig. 1, comprising: the control device 100 and the plurality of inverters 201-n connected to the control device 100, referring to fig. 11, the control device 100 includes a sampling module 110, a processing module 120, and a driving module 130;

the sampling module 110 is configured to obtain a plurality of phase current instantaneous values of each inverter in a current period;

the processing module 120 is configured to obtain an expected voltage of a next period and a voltage compensation value of each inverter according to a plurality of phase current instantaneous values corresponding to all inverters, and obtain an input voltage vector value of each inverter in the next period according to the expected voltage and the voltage compensation value of the next period;

and the driving module 130 is configured to control the corresponding inverter to operate according to the input voltage of the next period.

In one particular embodiment, the processing module includes: the current sharing control system comprises a first processing module, a current transformation module and a current sharing adjusting module;

In a specific embodiment, the first processing module is specifically configured to: and respectively carrying out digital filtering processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter.

In one embodiment, the current transformation module comprises:

the angle acquisition unit is used for acquiring the current coordinate system angle of each inverter in the current period;

and the transformation unit is used for transforming the target current from the current coordinate system to the target coordinate system through current coordinate transformation according to the current coordinate system angle to obtain a current vector value of the target current in the target coordinate system.

The first processing module is specifically configured to:

respectively carrying out digital filtering processing on all second instantaneous currents in the multiple groups of three-phase instantaneous currents corresponding to each inverter to obtain second target currents of each inverter,

In one embodiment, the current share regulating module specifically includes:

the current-sharing control system comprises a calculating unit, a current-sharing adjusting unit and an output unit, wherein the calculating unit comprises a first calculating unit and a second calculating unit.

The first calculation unit is used for acquiring an expected voltage vector value of the next period according to the current vector values of all the inverters;

the second calculation unit is also used for acquiring a circulating current vector difference value corresponding to each inverter according to the current vector values of all the inverters;

the current-sharing adjusting unit is used for carrying out second processing on the circulating current vector difference value to obtain a voltage compensation value corresponding to each inverter;

and the output unit is used for summing the voltage compensation value and the expected voltage vector value of the next period to obtain the input voltage vector value of the next period of each inverter.

In a specific embodiment, the second calculating unit specifically includes:

the first sub-calculation unit is used for averaging the current vector values of all the inverters to obtain a current vector average value;

and the second sub-calculation unit is used for taking the difference value of the current vector value of the inverter and the average value of the current vector as the circulating current vector difference value of the corresponding inverter.

In a specific embodiment, the driving module 130 is specifically configured to convert the input voltage vector value of the next period into a voltage driving signal, and send the voltage driving signal to the corresponding inverter to control the corresponding inverter to operate.

Fig. 12 is a block diagram of a current sharing control system in another embodiment. Referring to fig. 12, the sampling module 110 includes a plurality of sub-sampling units, and the processing module 120 includes a first processing module, a current transformation module, and a current-sharing adjustment module; the first processing module comprises a plurality of sub-processing units 1-n.

The current transformation module comprises a plurality of angle acquisition units and a plurality of transformation units, wherein one angle acquisition unit and one transformation unit form one sub-current transformation unit, namely, the current transformation module comprises a plurality of sub-current transformation units 1-n.

The current-sharing regulation module specifically comprises: the current-sharing control system comprises a computing unit, a current-sharing adjusting unit and an output unit, wherein the current-sharing adjusting unit comprises a plurality of sub current-sharing adjusting units 1-n, and the output unit comprises a plurality of sub output units.

The driving module 130 includes a plurality of sub driving units 1-n.

Each inverter is sequentially connected with one sub-sampling unit, one sub-processing unit and one sub-current conversion unit, the sub-current conversion units are commonly connected with a calculation unit, the calculation unit is connected with a plurality of sub-current-sharing regulation units, each sub-current-sharing regulation unit is sequentially connected with one corresponding sub-output unit and one corresponding sub-drive unit, and the sub-drive unit is connected with one inverter which is controlled correspondingly.

The sub-sampling unit is used for acquiring a plurality of phase current instantaneous values of the inverter correspondingly connected in the current period.

The sub-processing unit is used for carrying out digital filtering processing on a plurality of phase current instantaneous values corresponding to the corresponding inverters to obtain target current in a corresponding inverter target frequency range section.

The sub-current conversion unit is used for acquiring a current vector value of a target current of the corresponding inverter.

The computing unit comprises a first computing unit and a second computing unit.

and the second calculating unit is also used for acquiring a circulating current vector difference value corresponding to each inverter according to the current vector values of all the inverters.

And the sub-current-sharing adjusting unit is used for carrying out second processing on the circulating current vector difference value of the corresponding inverter to obtain a voltage compensation value of the corresponding inverter.

And the sub-output unit is used for summing the voltage compensation value of the corresponding inverter and the expected voltage vector value of the next period to obtain an input voltage vector value of the next period of the corresponding inverter.

And the sub-driving unit is used for controlling the corresponding inverter to work according to the input voltage of the next period of the corresponding inverter.

The technical scheme of this application can successfully be used at middling pressure high-power converter rectification side and contravariant side homoenergetic, and the actual measurement can all realize flow equalizing fast in ms level time under each contravariant unit of parallel machine artificially independently sets up different length cables respectively, inserts various blind areas, different heat radiation environment etc. various simulation operating mode.

In one embodiment, a computer device is provided, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor implementing the following steps when executing the computer program: acquiring a plurality of phase current instantaneous values corresponding to each inverter in the current period; obtaining expected voltage of the next period and voltage compensation values of all inverters according to a plurality of phase current instantaneous values corresponding to all the inverters, and obtaining input voltage of each inverter in the next period according to the expected voltage and the voltage compensation values of the next period; and controlling the corresponding inverter to work according to the input voltage of the next period.

In one embodiment, a computer-readable storage medium is provided, having a computer program stored thereon, which when executed by a processor, performs the steps of: acquiring a plurality of phase current instantaneous values corresponding to each inverter in the current period; obtaining expected voltage of the next period and voltage compensation values of all inverters according to a plurality of phase current instantaneous values corresponding to all the inverters, and obtaining input voltage of each inverter in the next period according to the expected voltage and the voltage compensation values of the next period; and controlling the corresponding inverter to work according to the input voltage of the next period.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for current sharing control, the method comprising:

obtaining an expected voltage of a next period and a voltage compensation value of each inverter according to a plurality of phase current instantaneous values corresponding to all the inverters, and obtaining an input voltage vector value of each inverter in the next period according to the expected voltage and the voltage compensation value of the next period, wherein the expected voltage of the next period is a state which all the inverters in the next period are expected to reach, and the voltage compensation value refers to a voltage difference value from a state of a current period to an expected state of the next period of each inverter;

obtaining an expected voltage of a next period and a voltage compensation value of each inverter according to a plurality of phase current instantaneous values corresponding to all inverters, and obtaining an input voltage vector value of each inverter in the next period according to the expected voltage and the voltage compensation value of the next period, wherein the method comprises the following steps:

respectively carrying out first processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter; the method for respectively carrying out first processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter comprises the following steps: respectively carrying out digital filtering processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band interval of each inverter; acquiring a current vector value of the target current;

obtaining an expected voltage vector value of a next cycle and a voltage compensation value of each inverter according to current vector values of the target current of all inverters, obtaining an input voltage vector value of a next cycle of each inverter according to an expected voltage vector value and a voltage compensation value of the next cycle, wherein the obtaining of an expected voltage vector value of a next cycle and a voltage compensation value of each inverter according to current vector values of the target current of all inverters and the obtaining of an input voltage vector value of a next cycle of each inverter according to an expected voltage vector value and a voltage compensation value of the next cycle comprise: obtaining an expected voltage vector value of the next period according to the current vector values of the target currents of all the inverters; acquiring a circulating current vector difference value corresponding to each inverter according to the current vector values of the target currents of all the inverters; carrying out second processing on the circulating current vector difference value to obtain a voltage compensation value corresponding to each inverter; the second processing is performed on the circulating current vector difference value to obtain a voltage compensation value corresponding to each inverter, and the method specifically includes: inputting the circulating current vector difference value into a PI controller, and obtaining an output value as a voltage compensation value of a corresponding inverter through proportional regulation and integral regulation; summing the voltage compensation value and an expected voltage vector value of the next period to obtain an input voltage vector value of each inverter in the next period;

and controlling the corresponding inverter to work according to the input voltage vector value of the next period.

2. The method of claim 1, wherein obtaining a current vector value for the target current comprises:

and converting the target current from the current coordinate system to a target coordinate system through current coordinate conversion according to the current coordinate system angle to obtain a current vector value of the target current in the target coordinate system.

3. The method according to claim 2, wherein when the current coordinate system is a three-phase stationary coordinate system and the target coordinate system is a two-phase orthogonal rotating coordinate system, the plurality of phase current instantaneous values are a plurality of sets of three-phase instantaneous currents in the three-phase stationary coordinate system, and the target current is a three-phase current in the three-phase stationary coordinate system.

4. The method of claim 3, wherein each set of three-phase instantaneous currents comprises a first instantaneous current, a second instantaneous current, a third instantaneous current, and the target currents comprise a first target current, a second target current, a third target current;

5. The method of claim 1, wherein obtaining a circulating current vector difference value for each inverter based on current vector values of the target currents for all inverters comprises:

averaging the current vector values of the target current of all inverters to obtain a current vector average value;

and taking the difference value of the current vector value of the target current of the inverter and the average value of the current vectors as the circulating current vector difference value of the corresponding inverter.

6. The method of claim 5, wherein controlling the operation of the corresponding inverter according to the input voltage vector value of the next cycle comprises:

and converting the input voltage vector value of the next period into a voltage driving signal, and sending the voltage driving signal to a corresponding inverter so as to control the corresponding inverter to work.

7. A current share control system, the system comprising: the system comprises a control device and a plurality of inverters connected with the control device, wherein the control device comprises a sampling module, a processing module and a driving module;

the processing module is used for obtaining an expected voltage of a next period and a voltage compensation value of each inverter according to a plurality of phase current instantaneous values corresponding to all the inverters, and obtaining an input voltage vector value of the next period of each inverter according to the expected voltage and the voltage compensation value of the next period, wherein the expected voltage of the next period is a state which all the inverters in the next period are expected to reach, and the voltage compensation value refers to a voltage difference value from a current period state to an expected state of the next period of each inverter; the processing module comprises:

the first processing module is used for respectively carrying out first processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band section of each inverter; the first processing module is specifically configured to: respectively carrying out digital filtering processing on a plurality of phase current instantaneous values corresponding to each inverter to obtain a target current in a target frequency band interval of each inverter;

the current-sharing adjusting module is used for obtaining an expected voltage vector value of a next period and a voltage compensation value of each inverter according to the current vector values of the target currents of all the inverters, and obtaining an input voltage vector value of the next period of each inverter according to the expected voltage vector value and the voltage compensation value of the next period, wherein the current-sharing adjusting module comprises: a first calculation unit for obtaining an expected voltage vector value of a next cycle from current vector values of the target currents of all inverters; the second calculation unit is further used for acquiring a circulating current vector difference value corresponding to each inverter according to the current vector values of the target currents of all the inverters; and the current-sharing adjusting unit is used for carrying out second processing on the circulating current vector difference value to obtain a voltage compensation value corresponding to each inverter, wherein the current-sharing adjusting unit is specifically used for: inputting the circulating current vector difference value into a PI controller, and obtaining an output value as a voltage compensation value of a corresponding inverter through proportional regulation and integral regulation; summing the voltage compensation value and an expected voltage vector value of the next period to obtain an input voltage vector value of each inverter in the next period; the output unit is used for summing the voltage compensation value and the expected voltage vector value of the next period to obtain the input voltage vector value of the next period of each inverter;

and the driving module is used for controlling the corresponding inverter to work according to the input voltage vector value of the next period.