CN104218836A - Circulating current control method and device for parallel power converters - Google Patents

Abstract

The invention discloses a circulating current control method for parallel power converters. The method includes the steps of 1, calculating magnitude of circulating current of k moment according to a circulating current value of the k moment; 2, adjusting a phase position of a k moment carrier signal according to a phase shift; 3, calculating magnitude of circulating current of k+g (g>/=1) moment according to a circulating current value of the k+g moment; 4, determining changes in the magnitude of the circulating current before and after phase adjustment; 5, adjusting the phase position of a k+g (g>/=1) moment carrier signal according to the changes in the magnitude of the circulating current. The method has the advantages that circulating current caused by a phase difference among PWM (pulse width modulation) carrier signals of power converters in a parallel power conversion system can be suppressed effectively and reliably, the limitation on the quantity of the parallel power converters in parallel power conversion equipment is avoided, and circulating current suppression is convenient to implement. The invention further discloses a control device employing the circulating current control method for parallel power converters.

Description

Parallel power converting means circular current control method and control device thereof

Technical field

The present invention relates to power-converting device control field, particularly relate to a kind of parallel power convertor device circular current control method be made up of multiple power converter.The invention still further relates to a kind of control device for parallel power converting means.

Background technology

Power-converting device parallel technology expands power-converting device power, improves reliability, realizes the important technical that power-converting device power adjusts flexibly.Circulation is the problem that parallel power converting means must solve, and this makes circulation control technology become key and the core of power-converting device parallel technology.Chinese invention patent CN200810166314.3 (applying date: 2008.09.19) proposes to utilize the positive and negative busbar voltage difference of the inverter forming many power-converting devices and circulation detected value sum to control circulation.Chinese invention patent CN201110275998.2 (applying date: 2011.09.08) proposes by respectively producing a residual voltage at three-phase and being injected into this phase voltage command, by this to the correction of this phase voltage command, thus realizes the control to circulation.Chinese invention patent CN200710121110.3 (applying date: 2007.08.30) proposes the action time being regulated zero vector by the proportionate relationship between action time of zero vector ppp in control SVM and the action time of nnn, thus reaches the object of the zero sequence circulation between back-to-back converter.Document 1 (Analysis of parallel operation methods of PWM inverters sets for an ultra-high speed elevator, IEEE, 2000, P944-950) a kind of circular current control method based on controlling with spill current is proposed.Document 2 (adopts the shunt chopper control technology that reference voltage regulates, Electric Machines and Control, 2011 (2): P84-88) voltage compensation signal proposing to be exported by circulation controller compensates the torque voltage signal that motor current controller exports thus realizes loop current suppression.Document 3 (Distributed Control for AC Motor Drive Inverters in Parallel Operation, IEEE Tran.I.E., 2011:58 (12), 5361-5370) propose to utilize line synchro to realize the synchronous of modulating wave by synchronous control mode, asynchronous between eliminating because of each inverter output voltage with this.

Research shows, the phase difference situation formed between the carrier signal in each power converter PWM of parallel power convertor device has material impact to the circulation in parallel power convertor device: the phase difference between carrier signal is larger, and circulation is also larger.For the circulation in the parallel power convertor device that the phase difference by intercarrier causes, above-mentioned prior art or do not relate to, though or have and relate to, but its regulating object is modulating wave but not carrier signal (as document 3), the circulation in the parallel power convertor device that the phase difference between therefore cannot utilizing above-mentioned prior art to eliminate by carrier signal causes.For this problem, can utilize to adopt in engineering practice and carry out the PWM of each power converter based on same clock signal or eliminate the phase difference between carrier signal by bus mode, communication modes etc., and then eliminate the circulation in the parallel power convertor device that caused by the phase difference between carrier signal.But when in parallel power convertor device, the quantity of parallel power converter is too much, cannot be able to tackle because of the PWM port resource restriction of controller based on same clock signal method; Bus mode, communication modes etc. need to set up line synchro (synchronization line), communication line etc., and when line synchro, communication line easily cause phase difference variable between carrier signal large after receiving interference, and then larger circulation is caused to occur.In addition, even if after eliminating the phase difference between carrier signal based on same clock signal method or the method such as bus mode, communication modes, it is inconsistent that the pwm switching signal generated still may cause pwm switching signal to produce before and after drive amplification because of the nuance of drive amplification circuit self or external interference etc. before delivering to power model through the drive amplification of drive amplification circuit, thus cause parallel power convertor device person to occur larger circulation.

Therefore, how reliably and effectively suppress the circulation caused because of the phase difference between the PWM carrier signal of each power converter in parallel power changer system just to become of power-converting device parallel technology by the restricted number of parallel power converter in connection power converter apparatus and have important technological problems to be solved.

Summary of the invention

The technical problem to be solved in the present invention proposes a kind of parallel power converting means circular current control method, the method effectively, reliably can suppress the circulation caused because of the phase difference between the PWM carrier signal of each power converter in parallel power changer system, and by restricted number, the loop current suppression realization convenience of parallel power converter in connection power converter apparatus.

For solving the problems of the technologies described above, the technical solution of parallel power converting means circular current control method of the present invention is comprise the steps:

Step 1: the circulation size calculating the k moment according to the circulation value in k moment;

Step 2: utilize phase-shift phase to adjust k moment carrier signal phase;

Step 3: the circulation size calculating the k+g moment according to the circulation value in k+g moment, wherein g >=1;

Step 4: the situation of change determining circulation size before and after phase place adjustment;

Step 5: according to the carrier signal phase in the situation of change adjustment k+g moment of circulation size, wherein g >=1.

That monotonic increasing function f realizes by circulation value to be expressed as with circulation value be independent variable for the calculating of circulation size in described step 1 and step 3.

Described step 5 adjusts carrier signal phase according to following arbitrary rule:

Rule 1: if f ₁>f ₂, i.e. △ f<0, then keep Ph (k+g) currency constant, otherwise Ph (k+g) ← Ph (k), △ Ph ←-△ Ph;

Rule 2: if f ₁>f ₂, i.e. △ f<0, then keep Ph (k+g) currency constant, otherwise Ph (k+g) ← Ph (k)-△ Ph;

Rule 3: if △ is f≤α, keep Ph (k+g) currency constant, if α < △ f< is β, Ph (k+g) ← Ph (k), if β≤△ f, then Ph (k+g) ← Ph (k)-△ Ph;

Wherein, f ₁for the circulation size in k moment in step 1; f ₂for the circulation size in k+g moment in step 3; △ f=f ₂-f ₁; Ph (k) is the carrier signal phase in k moment; The carrier signal phase that Ph (k+g) is the k+g moment; △ Ph is phase-shift phase, ← be assignment operator; α, β are respectively preset value, and α < β.

Described phase-shift phase △ Ph meets following condition:

0<△Ph≤0.5×T _car×ω _e

Wherein T _cardescribed year wave period, ω _eelectrical angle speed.

Described phase-shift phase △ Ph is a steady state value preset.

Or, the function that described phase-shift phase △ Ph is is independent variable with circulation size function f or circulation size variation amount △ f; Phase-shift phase △ Ph is according to following arbitrary formulae discovery:

△Ph=ζ×f×△Ph ₀；

△Ph=ζ×△f×△Ph ₀；

△Ph=ζ×f×△Ph ₀+δ×△f×△Ph ₀

In formula, benchmark phase-shift phase △ Ph ₀be the steady state value preset, ζ and δ is constant.

Described circular current control method continues to carry out for the adjustment of carrier phase; Or perform s time according to some cycles or when circulation size function f exceedes the threshold value preset, wherein s >=1; Or perform until circulation size function f stops after being no more than the threshold value preset again continuously.

Steps A is performed: the circulation value calculating the k moment according to the current value in k moment before described step 1;

Step B is performed before step 3: the circulation value calculating the k+g moment according to the current value in k+g moment after described step 2.

The present invention also provides a kind of control device for parallel power converting means, and described control device comprises:

Current controller; Current controller controls according to the current feedback values of current instruction value and each parallel power converting means, exports modulation signal;

Carrier signal generator; Carrier signal generator generates the carrier signal needed for PWM unit;

PWM unit; The modulation signal that PWM unit exports according to current controller and the carrier signal that carrier signal generator generates carry out pulse-width modulation, export the switching signal for controlling power model;

Also comprise:

Calculation of circulating current device; Calculation of circulating current device is according to the testing result ring flow valuve of current detector;

Circulation size counter; Circulation size counter calculates circulation size according to the result of calculation of described calculation of circulating current device;

Phase regulator; The circulation size that phase regulator exports according to circulation size counter, utilizes aforesaid method to adjust the carrier signal phase that described carrier signal generator generates.

Or described control device comprises:

Current controller; Current controller controls according to the current feedback values of current instruction value and each parallel power converting means, exports control voltage moment components;

Calculation of circulating current device; Calculation of circulating current device is according to the testing result ring flow valuve of current detector;

Circulation controller; The circulation value that circulation controller exports according to circulation command value and described calculation of circulating current device controls, and exports control voltage loop current suppression component;

Carrier signal generator; Carrier signal generator generates the carrier signal needed for PWM unit;

Modulation signal maker; The control voltage moment components that modulation signal maker exports according to described current controller and the control voltage loop current suppression component that described circulation controller exports generate modulation signal;

PWM unit; The modulation signal that PWM unit exports according to described modulation signal maker and the carrier signal that carrier signal generator generates carry out pulse-width modulation, export the switching signal for controlling power model;

Wherein, also comprise:

Circulation size counter; Circulation size counter calculates circulation size according to the result of calculation of described calculation of circulating current device;

Phase regulator; The circulation size that phase regulator exports according to circulation size counter, utilizes aforesaid method to adjust the carrier signal phase that described carrier signal generator generates.

The difference based on the methods such as same clock signal, bus mode, communication modes (follow-up be called engineering method) in parallel power converting means circular current control method of the present invention and engineering practice is:

A, the inventive method utilize software algorithm to implement completely, cannot increase additional hardware resources, and the enforcement of engineering method then depends on line synchro, communication line etc.;

B, the present invention are the circulation directly being suppressed parallel power converting means person by the phase place of adjustment parallel connection converter carrier signal, and engineering method is then indirectly suppress the circulation of parallel power converting means person (therefore cannot tackle pwm switching signal and produce this situation inconsistent before and after drive amplification) by eliminating based on same clock signal, line synchro, communication line etc. by the phase difference between carrier signal;

The closed-loop fashion that c, the inventive method adopt for the suppression of the circulation caused by the phase difference between carrier signal, and engineering method adopts for the elimination of phase difference between carrier signal is open loop approach, suppression for the circulation caused by the phase difference between carrier signal is open loop approach equally, and obvious closed-loop fashion of the present invention is better than the open loop approach of engineering method.

The beneficial effect that the present invention can reach is:

A, when without the need to increasing additional hardware resources completely depended software to control effectively to suppress by carrier signal between phase difference indirectly suppress the circulation of parallel power converting means person;

B, can there is reply pwm switching signal before and after drive amplification, produce inconsistent and this particular application of circulation that is that cause;

C, directly judge that whether phase place adjustment is suitable with loop current suppression effect, therefore loop current suppression effect is more direct, rapid, accurate.

Accompanying drawing explanation

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail:

Fig. 1 is a kind of structural representation that the parallel power transformation system applying parallel power converting means circular current control method of the present invention is applied to electric machine speed regulation;

Fig. 2 is the another kind of structural representation that the parallel power transformation system applying parallel power converting means circular current control method of the present invention is applied to electric machine speed regulation.

Embodiment

The application of parallel power converting means circular current control method of the present invention---parallel power transformation system comprises control device two parts of parallel power converting means and parallel power converting means, wherein parallel power converting means is made up of at least two power converters be connected in parallel and corresponding reactor, here power converter can be two-phase, three-phase or even more heterogeneous inverter or PWM rectifier, the corresponding of AC of power converter is connected after the corresponding reactor of serial connection, be connected to load or power supply (electrical network or Blast Furnace Top Gas Recovery Turbine Unit (TRT)) afterwards again, be connected with common DC power supply or Equivalent DC power supply (DC side as diode rectifier) again after all anodes of power converter DC side are connected respectively with all negative terminals, or power converter DC side is connected with respective independently DC power supply (or Equivalent DC power supply) respectively, or be connected with common DC power supply or Equivalent DC power supply (DC side as diode rectifier) again after the DC side anode of some electrical power converter is connected respectively with negative terminal, the DC side of all the other power converters is connected with respective independently DC power supply (or Equivalent DC power supply) respectively, the control device of parallel power converting means comprises current-order generator, current controller, PWM unit, carrier signal generator etc.

Next for the parallel power converting means shown in Fig. 1 to parallel power converting means circular current control method of the present invention be described for the control device of parallel power converting means.It is pointed out that the application of parallel power converting means circular current control method of the present invention is not limited to the parallel power converting means of the particular type in Fig. 1, and the power converter forming parallel power converting means can be 2 or multiple.

For simplifying follow-up describing, in subsequent embodiment with the parallel power converting means being formed, with motor be load by 2 inverters of same DC power supply as shown in Figure 1 for application is described parallel power converting means circular current control method of the present invention.

Embodiment 1

As shown in Figure 1, parallel power transformation system comprises control device two parts of parallel power converting means and parallel power converting means, and wherein parallel power converting means comprises the 1# inverter that is connected in parallel and 2# inverter, 1 DC power supply, 1# current detector and 2# current detector further; Each inverter is controlled by the control device of parallel power converting means respectively; The control device of parallel power converting means comprises current-order generator (being speed control), current controller, calculation of circulating current device, circulation controller, modulation signal maker and PWM unit, carrier signal generator further herein; 1# inverter is connected with DC power supply after being connected with the identical polar end of the DC side of 2# inverter again, the corresponding reactor L be connected in series separately at warp of the AC of 1# inverter and 2# inverter ₁, L ₂connected to each other afterwards, be connected to its common load (in the present embodiment, common load is a motor) afterwards; The control device of parallel power converting means is used for carrying out switch control rule to the power model in 1# inverter in parallel power converting means and 2# inverter; In addition, control based on parallel control device needs, parallel power transformation system of the present invention also comprises for common load, namely the motor in the present embodiment, carry out the load sensor detected, as the speed detector in the present embodiment---encoder or other can realize rotate detect detector;

The motor speed that speed control detects according to speed detector and speed command control, output torque current-order; The alternating current i of the 1# inverter that the torque current command that current controller exports according to speed control and 1# current detector and 2# current detector detect and 2# inverter ac side ₁, i ₂control, export 1# control voltage moment components and 2# control voltage moment components respectively; The alternating current i of the 1# inverter that calculation of circulating current device detects according to 1# current detector and 2# current detector and 2# inverter ac side ₁, i ₂calculate respective circulation value (as: calculate the difference between each phase current of inverter and the current average of the corresponding phase in all inverter ac sides and it can be used as the circulation value of this inverter), the circulation value that circulation controller then calculates according to calculation of circulating current device and circulation instruction (being generally zero) control, and export control voltage loop current suppression component; The 1# control voltage moment components that 1# modulation signal maker exports according to current controller and the 1# control voltage loop current suppression component that 1# circulation controller exports generate the modulation signal of 1# inverter and deliver to 1#PWM unit, and the modulation signal of the 2# control voltage moment components that 2# modulation signal maker exports according to current controller and the 2# control voltage loop current suppression component generation 2# inverter that 2# circulation controller exports also delivers to 2#PWM unit;

Calculation of circulating current device is according to the current i of 1# inverter and 2# inverter ac side ₁, i ₂calculate the circulation value of k moment parallel power converting means; The electric current of 1# inverter herein and 2# inverter ac side can be the detected value of each phase current of 1# inverter and 2# inverter ac side that 1# current detector and 2# current detector detect, also can be the current value that described current detection value obtains after coordinate transform; The circulation value (the follow-up 2# of being referred to as circulation) of the 2# power converter that the circulation value (the follow-up 1# of being referred to as circulation) of the 1# power converter that 1# circulation size counter and 2# circulation size counter calculate according to 1# calculation of circulating current device respectively and 2# calculation of circulating current device calculate calculates the circulation size (follow-up be referred to as 2# circulation size) of the circulation size (the follow-up 1# of being referred to as circulation size) of 1# power converter and 2# power converter, and the 1# circulation size that 1# phase regulator and 2# phase regulator calculate according to 1# circulation size device and 2# circulation size device respectively and 2# circulation size export respective phase adjustment and deliver to respective carrier signal generator; The phase adjustment that 1# carrier signal generator and 2# carrier signal generator export according to respective phase regulator respectively adjusts the carrier signal phase that it exports;

The output of the carrier signal that 1#PWM unit and 2#PWM unit generate according to its carrier signal generator respectively and 1# modulation signal maker and 2# modulation signal maker generates 1# switching signal and 2# switching signal respectively, and 1# switching signal and 2# switching signal carry out switch control rule at the power model delivered to respectively in 1# inverter and 2# inverter after the necessary process such as drive amplification.

The method that the carrier signal phase that phase regulator exports carrier signal generator adjusts comprises the steps:

Step 1: circulation size counter calculates the circulation size in k moment according to the circulation value in k moment;

Circulation size counter is that monotonic increasing function f realizes by circulation value to be expressed as with circulation value be independent variable for the calculating of circulation size; Specifically, monotonic increasing function f can take any one in following form:

f(t)=∑ _j|i _{cir_j}(t)|； f(t)=max _j|i _{cir_j}(t)|；

$f\left(t\right)={\mathrm{\&Sigma;}}_j\left(i_{{\mathrm{cir}}_j}^m\left(t\right)\right);$ $f\left(t\right)={\max }_j\left(i_{\mathrm{cir}\_j}^m\left(t\right)\right);$

$f\left(t\right)={\mathrm{\&Sigma;}}_j{\left(i_{\mathrm{cir}\_j}^2\left(t\right)\right)}^{(1/n)};$ $f\left(t\right)={\max }_j{\left(i_{\mathrm{cir}\_j}^2\left(t\right)\right)}^{(1/n)};$

$f\left(t\right)={\mathrm{\&Sigma;}}_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}\left|i_{\mathrm{cir}\_j}\left(t\right)\right|\mathrm{dt};$ $f\left(t\right)=\frac{1}{\mathrm{\&Delta;t}}{\mathrm{\&Sigma;}}_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}\left|i_{\mathrm{cir}\_j}\left(t\right)\right|\mathrm{dt};$

$f\left(t\right)={\max }_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}\left|i_{\mathrm{cir}\_j}\left(t\right)\right|\mathrm{dt};$ $f\left(t\right)=\frac{1}{\mathrm{\&Delta;t}}{\max }_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}\left|i_{\mathrm{cir}\_j}\left(t\right)\right|\mathrm{dt};$

$f\left(t\right)={\mathrm{\&Sigma;}}_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}{i}_{\mathrm{cir}\_j}^m\left(t\right)\mathrm{dt};$ $f\left(t\right)=\frac{1}{\mathrm{\&Delta;t}}{\mathrm{\&Sigma;}}_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}{i}_{\mathrm{cir}\_j}^m\left(t\right)\mathrm{dt};$

$f\left(t\right)={\max }_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}{i}_{\mathrm{cir}\_j}^m\left(t\right)\mathrm{dt};$ $f\left(t\right)=\frac{1}{\mathrm{\&Delta;t}}{\max }_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}{i}_{\mathrm{cir}\_j}^m\left(t\right)\mathrm{dt};$

$f\left(t\right)={\mathrm{\&Sigma;}}_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}{\left(i_{\mathrm{cir}\_j}^2\left(t\right)\right)}^{(1/n)}\mathrm{dt};$ $f\left(t\right)=\frac{1}{\mathrm{\&Delta;t}}{\mathrm{\&Sigma;}}_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}{\left(i_{\mathrm{cir}\_j}^2\left(t\right)\right)}^{(1/n)}\mathrm{dt};$

$f\left(t\right)={\max }_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}{\left(i_{\mathrm{cir}\_j}^2\left(t\right)\right)}^{(1/n)}\mathrm{dt};$ $f\left(t\right)=\frac{1}{\mathrm{\&Delta;t}}{\max }_j{\&Integral;}_t^{t+\mathrm{\&Delta;t}}{\left(i_{\mathrm{cir}\_j}^2\left(t\right)\right)}^{(1/n)}\mathrm{dt}$

In formula, | * | be signed magnitude arithmetic(al) symbol, m is positive even numbers, and n is any positive integer, and j is each electric current numbering of converter to be adjusted, and △ t is any arithmetic number; Or

f(k)=∑ _j|i _{cir_j}(k)|； f(k)=max _j|i _{cir_j}(k)|；

$f\left(k\right)={\mathrm{\&Sigma;}}_j\left(i_{{\mathrm{cir}}_j}^m\left(k\right)\right);$ $f\left(k\right)={\max }_j\left(i_{\mathrm{cir}\_j}^m\left(k\right)\right);$

$f\left(k\right)={\mathrm{\&Sigma;}}_j{\left(i_{\mathrm{cir}\_j}^2\left(k\right)\right)}^{(1/n)};$ $f\left(k\right)={\max }_j{\left(i_{\mathrm{cir}\_j}^2\left(k\right)\right)}^{(1/n)};$

$f\left(k\right)={\mathrm{\&Sigma;}}_j{\mathrm{\&Sigma;}}_{p=k-l}^k\left|i_{\mathrm{cir}\_j}\left(p\right)\right|;$ $f\left(k\right)=\frac{1}{l\&times;T_{\mathrm{car}}}{\mathrm{\&Sigma;}}_j{\mathrm{\&Sigma;}}_{p=k-l}^k\left|i_{\mathrm{cir}\_j}\left(p\right)\right|;$

$f\left(k\right)={\max }_j{\mathrm{\&Sigma;}}_{p=k-l}^k\left|i_{\mathrm{cir}\_j}\left(p\right)\right|;$ $f\left(k\right)=\frac{1}{l\&times;T_{\mathrm{car}}}{\max }_j{\mathrm{\&Sigma;}}_{p=k-l}^k\left|i_{\mathrm{cir}\_j}\left(p\right)\right|;$

$f\left(k\right)={\mathrm{\&Sigma;}}_j{\mathrm{\&Sigma;}}_{p=k-l}^k{i}_{\mathrm{cir}\_j}^m\left(p\right);$ $f\left(k\right)=\frac{1}{l\&times;T_{\mathrm{car}}}{\mathrm{\&Sigma;}}_j{\mathrm{\&Sigma;}}_{p=k-l}^k{i}_{\mathrm{cir}\_j}^m\left(p\right);$

$f\left(k\right)={\max }_j{\mathrm{\&Sigma;}}_{p=k-l}^k{i}_{\mathrm{cir}\_j}^m\left(p\right);$ $f\left(k\right)=\frac{1}{l\&times;T_{\mathrm{car}}}{\max }_j{\mathrm{\&Sigma;}}_{p=k-l}^k{i}_{\mathrm{cir}\_j}^m\left(p\right);$

$f\left(k\right)={\mathrm{\&Sigma;}}_j{\mathrm{\&Sigma;}}_{p=k-l}^k{\left(i_{\mathrm{cir}\_j}^2\left(p\right)\right)}^{(1/n)};$ $f\left(k\right)=\frac{1}{l\&times;T_{\mathrm{car}}}{\mathrm{\&Sigma;}}_j{\mathrm{\&Sigma;}}_{p=k-l}^k{\left(i_{\mathrm{cir}\_j}^2\left(p\right)\right)}^{(1/n)};$

$f\left(k\right)={\max }_j{\mathrm{\&Sigma;}}_{p=k-l}^k{\left(i_{\mathrm{cir}\_j}^2\left(p\right)\right)}^{(1/n)};$ $f\left(k\right)=\frac{1}{l\&times;T_{\mathrm{car}}}{\max }_j{\mathrm{\&Sigma;}}_{p=k-l}^k{\left(i_{\mathrm{cir}\_j}^2\left(p\right)\right)}^{(1/n)}$

In formula, | * | be signed magnitude arithmetic(al) symbol, m is positive even numbers, l and n is any positive integer, and nonnegative integer l≤k, j is each phase current numbering of power converter, T _carit is described year wave period.

Obviously, utilize function f, calculation of circulating current device can calculate the circulation size f of each power converter according to the current value of each power converter ₁and f ₂.

Step 2: phase regulator utilizes phase-shift phase to adjust k moment carrier signal phase;

Phase regulator increases or reduces a phase-shift phase in the carrier signal phase of power converter, and phase-shift phase is a non-zero real; Consider and increase positive phase-shift phase and reduce negative phase-shift phase equivalence, increase negative phase-shift phase and reduce positive phase-shift phase equivalence, simple for stating, be increase by phase-shift phase by the unification of above-mentioned four kinds of adjustment modes in follow-up explanation; The carrier signal phase in k+g (g >=1, under normal circumstances, g=1) moment can be expressed as:

Ph(k+g)←Ph(k)+△Ph

In formula, Ph (k+1) and Ph (k) is the carrier signal phase in k moment and k+1 moment respectively, and △ Ph is phase-shift phase, ← be assignment operator;

After obtaining the carrier phase in k+g moment, 1# and 2# carrier signal generator is namely according to the phase generated carrier signal after adjustment, 1# and 2#PWM unit is modulated according to the carrier signal after phase place adjustment.

Step 3: circulation size counter calculates the circulation size in k+g (g >=1) moment according to the circulation value in k+g moment;

Because of the modulation of k+g (g>=1) moment 2#PWM unit be based on phase place adjustment after carrier signal carry out, the circulation size f in the parallel power converting means after therefore circulation size computational methods utilize the circulation value in k+g (g>=1) moment can calculate carrier signal phase adjustment in follow procedures 1 ₂.

Step 4: the situation of change of circulation size before and after the adjustment of phase regulator determination phase place;

According to the f in step 1 ₁with the f in step 3 ₂, directly judge f ₁and f ₂between magnitude relationship, or first calculate phase place adjustment before and after circulation size variation amount △ f=f ₂-f ₁judge that circulation is increase or reduce after phase place adjustment before adjusting according to the symbol of circulation size variation amount △ f again, or judge the relation between circulation size variation circulation size variation amount △ f and preset value α and β (α < β), namely judge in △ f≤α, α < △ f< β, β≤△ f, which relational expression is set up.

Step 5: the carrier signal phase in situation of change adjustment k+g (g >=1) moment of the circulation size that phase regulator obtains according to step 4.

The adjustment of k+g (g >=1) moment carrier signal phase can take following arbitrary rule:

Rule 1: if f ₁>f ₂, i.e. △ f<0, then keep Ph (k+g) currency constant, otherwise Ph (k+g) ← Ph (k), △ Ph ←-△ Ph;

Rule 2: if f ₁>f ₂, i.e. △ f<0, then keep Ph (k+g) currency constant, otherwise Ph (k+g) ← Ph (k)-△ Ph;

Rule 3: if △ is f≤α, keep Ph (k+g) currency constant, if α < △ f< is β, Ph (k+g) ← Ph (k), if β≤△ f, then Ph (k+g) ← Ph (k)-△ Ph.

In fact rule 2 is equivalent to: Ph (k+g) ← Ph (k)-sign (△ f) × △ Ph, wherein sign (*) is sign function.

In above-mentioned adjustment law, phase-shift phase △ Ph is satisfied following condition:

0<△Ph≤0.5×T _car×ω _e

Wherein T _cardescribed year wave period, ω _eelectrical angle speed.

In addition, phase-shift phase △ Ph is a steady state value preset, the function also can be being independent variable with circulation size function f and/or circulation size variation amount △ f, and phase-shift phase △ Ph can according to following arbitrary formulae discovery:

△Ph=ζ×f×△Ph ₀，△Ph=ζ×△f×△Ph ₀，

△Ph=ζ×f×△Ph ₀+δ×△f×△Ph ₀

In formula, benchmark phase-shift phase △ Ph ₀be the steady state value preset, ζ and δ is constant.

Circular current control method of the present invention continues to carry out for the adjustment of carrier phase, or according to some cycles or perform s (s >=1) when circulation size function f exceedes the threshold value preset secondary, or perform until circulation size function f stops after being no more than the threshold value preset again continuously.

The phase place of carrier signal generator corresponding with all PWM unit in embodiment 1 all adjusts.

In addition, calculation of circulating current can take following method:

When in parallel power converting means during inverter quantity n >=2, circulation is the difference between each phase current of inverter and the current average of the corresponding phase in all inverter ac sides; When in parallel power converting means during inverter quantity n=2, circulation also can be reduced to the difference between the corresponding phase current of 2 inverters.Now, a calculation of circulating current device and a circulation size counter can be only set, 1# phase regulator and 2# phase regulator export respective phase adjustment according to the result of calculation of circulation size counter respectively, thus realize adjusting the carrier signal phase of respective carrier signal generator.

Embodiment 2

As shown in Figure 2, the present embodiment is similar to embodiment 1, and difference is only to have minused circulation controller and modulation signal maker, and namely the output of current controller be sent to PWM unit as modulation signal, and all the other are identical with embodiment 1.

The method that the carrier signal phase that its phase regulator exports carrier signal generator adjusts comprises the steps:

Step 1: calculation of circulating current device calculates the circulation value in k moment according to the current value in k moment;

Step 2: circulation size counter calculates the circulation size in k moment according to the circulation value in k moment;

Step 3: phase regulator utilizes phase-shift phase to adjust k moment carrier signal phase;

Step 4: calculation of circulating current device calculates the circulation value in k+g moment according to the current value in k+g moment;

Step 5: circulation size counter calculates the circulation size in k+g moment according to the circulation value in k+g moment, wherein g >=1;

Step 6: the situation of change of circulation size before and after the adjustment of phase regulator determination phase place;

Step 7: phase regulator adjusts the carrier signal phase in k+g moment according to the situation of change of circulation size, wherein g >=1.

Obviously, compared with embodiment 1, the method that the carrier signal phase that phase regulator in the present embodiment exports carrier signal generator adjusts has had more the calculation of circulating current of step 1 and step 3, all the other are identical with embodiment 1 method, and step 1 is identical for the calculation of circulating current method providing the calculation of circulating current device of circulation value to adopt to circulation controller with embodiment 1 with the calculation of circulating current of step 3.

Claims (9)

1. a parallel power converting means circular current control method, is characterized in that: described control method comprises the steps:

Step 1: the circulation size calculating the k moment according to the circulation value in k moment;

Step 2: utilize phase-shift phase to adjust k moment carrier signal phase;

Step 3: the circulation size calculating the k+g moment according to the circulation value in k+g moment, wherein g >=1;

Step 4: the situation of change determining circulation size before and after phase place adjustment;

Step 5: according to the carrier signal phase in the situation of change adjustment k+g moment of circulation size, wherein g >=1.

2. parallel power converting means circular current control method according to claim 1, is characterized in that: be that monotonic increasing function f realizes by circulation value to be expressed as with circulation value be independent variable for the calculating of circulation size in described step 1 and step 3.

3. parallel power converting means circular current control method according to claim 1, is characterized in that: described step 5 adjusts carrier signal phase according to following arbitrary rule:

Rule 1: if f ₁>f ₂, i.e. △ f<0, then keep Ph (k+g) currency constant, otherwise Ph (k+g) ← Ph (k), △ Ph ←-△ Ph;

Rule 2: if f ₁>f ₂, i.e. △ f<0, then keep Ph (k+g) currency constant, otherwise Ph (k+g) ← Ph (k)-△ Ph;

Rule 3: if △ is f≤α, keep Ph (k+g) currency constant, if α < △ f< is β, Ph (k+g) ← Ph (k), if β≤△ f, then Ph (k+g) ← Ph (k)-△ Ph;

Wherein, f ₁for the circulation size in k moment in step 1; f ₂for the circulation size in k+g moment in step 3; △ f=f ₂-f ₁; Ph (k) is the carrier signal phase in k moment; The carrier signal phase that Ph (k+g) is the k+g moment; △ Ph is phase-shift phase, ← be assignment operator; α, β are respectively preset value, and α < β.

4. parallel power converting means circular current control method according to claim 3, is characterized in that: described phase-shift phase △ Ph meets following condition:

0<△Ph≤0.5×T _car×ω _e

Wherein T _cardescribed year wave period, ω _eelectrical angle speed.

5. parallel power converting means circular current control method according to claim 3, is characterized in that: described phase-shift phase △ Ph is a steady state value preset; Or,

The function that described phase-shift phase △ Ph is one is independent variable with circulation size function f or circulation size variation amount △ f; Phase-shift phase △ Ph is according to following arbitrary formulae discovery:

△Ph=ζ×f×△Ph ₀；

△Ph=ζ×△f×△Ph ₀；

△Ph=ζ×f×△Ph ₀+δ×△f×△Ph ₀

In formula, benchmark phase-shift phase △ Ph ₀be the steady state value preset, ζ and δ is constant.

6. parallel power converting means circular current control method according to claim 1, is characterized in that: described circular current control method continues to carry out for the adjustment of carrier phase;

Or perform s time according to some cycles or when circulation size function f exceedes the threshold value preset, wherein s >=1;

Or perform until circulation size function f stops after being no more than the threshold value preset again continuously.

7. parallel power converting means circular current control method according to claim 1, is characterized in that: perform steps A before described step 1: the circulation value calculating the k moment according to the current value in k moment;

Step B is performed before step 3: the circulation value calculating the k+g moment according to the current value in k+g moment after described step 2.

8., for a control device for parallel power converting means, described control device comprises:

Current controller; Current controller controls according to the current feedback values of current instruction value and each parallel power converting means, exports modulation signal;

Carrier signal generator; Carrier signal generator generates the carrier signal needed for PWM unit;

PWM unit; The modulation signal that PWM unit exports according to current controller and the carrier signal that carrier signal generator generates carry out pulse-width modulation, export the switching signal for controlling power model;

It is characterized in that, also comprise:

Calculation of circulating current device; Calculation of circulating current device is according to the testing result ring flow valuve of current detector;

Circulation size counter; Circulation size counter calculates circulation size according to the result of calculation of described calculation of circulating current device;

Phase regulator; The circulation size that phase regulator exports according to circulation size counter, utilizes the method described in any one of claim 1 to 7 to adjust the carrier signal phase that described carrier signal generator generates.

9., for a control device for parallel power converting means, described control device comprises:

Current controller; Current controller controls according to the current feedback values of current instruction value and each parallel power converting means, exports control voltage moment components;

Calculation of circulating current device; Calculation of circulating current device is according to the testing result ring flow valuve of current detector;

Circulation controller; The circulation value that circulation controller exports according to circulation command value and described calculation of circulating current device controls, and exports control voltage loop current suppression component;

Carrier signal generator; Carrier signal generator generates the carrier signal needed for PWM unit;

Modulation signal maker; The control voltage moment components that modulation signal maker exports according to described current controller and the control voltage loop current suppression component that described circulation controller exports generate modulation signal;

PWM unit; The modulation signal that PWM unit exports according to described modulation signal maker and the carrier signal that carrier signal generator generates carry out pulse-width modulation, export the switching signal for controlling power model;

It is characterized in that, also comprise:

Circulation size counter; Circulation size counter calculates circulation size according to the result of calculation of described calculation of circulating current device;

Phase regulator; The circulation size that phase regulator exports according to circulation size counter, utilizes the method described in any one of claim 1 to 7 to adjust the carrier signal phase that described carrier signal generator generates.