CN103532205B - A kind of modeling method of harmonic model of three-phase charger of electric vehicle - Google Patents

Abstract

The invention discloses a kind of modeling method of harmonic model of three-phase charger of electric vehicle, comprise according to the uncontrollable bridge rectifier equivalent electric circuit of three-phase, the time-domain expression of derivation electric automobile battery charger alternating current; According to charging current under two kinds of mode of operations of gained, build three-phase charger Harmonic coupling admittance matrix; Combined with the voltage of charger by time domain alternating current, propose the defining method of model parameter, this model considers the coupling of charger terminal voltage and harmonic current, and its matrix element does not change with charger harmonic voltage; According to described admittance matrix parameters computational methods, in conjunction with constructed by coupling admittance matrix, set up the harmonic-model of three-phase charger of electric vehicle, this model provides good theoretical foundation with the variation characteristic of charger number of units, charge power for the charging station harmonic current analyzed containing multiple stage charger, and the method directly can calculate the harmonic current of three-phase charger of electric vehicle effectively.

Description

A kind of modeling method of harmonic model of three-phase charger of electric vehicle

Technical field

The present invention relates to electric automobile field, particularly relate to a kind of modeling method of harmonic model of three-phase charger of electric vehicle.

Background technology

Along with the promotion and application of electric automobile, the scale of non-linear high-power charger access electrical network increases gradually, and this will bring load impact to electrical network, and produce on the quality of power supply, via net loss, utilization rate of equipment and installations etc. of electrical network the impact that can not be ignored.

Electric automobile battery charger adopts single-phase or rectified three-phase circuit usually, at american car engineering association (society of automotive engineers, SAE) be divided into Three Estate in charging inlet standard SAE J1772, the first order is the charging at a slow speed adopting single-phase uncontrollable rectification circuit; And other two-stages are routine (vehicle-mounted) and (non-vehicle-mounted) charging fast of adopting three phase rectifier, the charging interval scope of corresponding different capabilities charger is 0.2 to 6 hour, and wherein three-phase normal charge is the charging electric vehicle mode that application is the most general at present.Charger rectifier is typical harmonic-producing load, and its harmonic current, after electrical network transmits, will have a negative impact to other load, generator and the equipment such as monitoring and metering.Electric automobile battery charger harmonic source characteristic and the reciprocation with electrical network thereof, to assessment charger harmonic pollution, design Harmonic and braking measure most important.Therefore, the harmonic wave analytic modell analytical model furtheing investigate electric automobile battery charger is needed.

Existing analysis charger Characterization method mainly contains: time-domain-simulation, physical analogy etc.But these method amounts of calculation are large, be difficult to analytical Calculation.Have the literature research frequency domain analytic modell analytical model of single phase-controlled rectification circuit and uncontrollable rectification circuit at present, but consider that rectified three-phase circuit is different from single-phase rectifier, there is twice turn on process in its each diode, affect between turn on process may occur the situation that charging current is continuous and interrupted by DC load in half cycles.This makes the harmonic-model of three phase rectifier more complicated, and the modeling method of single-phase rectifier cannot be applied to electric automobile three phase rectifier charger.

Summary of the invention

For above shortcomings in prior art, the invention provides a kind of modeling method of harmonic model of three-phase charger of electric vehicle, consider the coupling of terminal voltage and harmonic current, AC individual harmonic current can be analyzed accurately and effectively.

In order to solve the problems of the technologies described above, present invention employs following technical scheme:

A kind of modeling method of harmonic model of three-phase charger of electric vehicle, according to the uncontrollable bridge rectifier equivalent electric circuit of described three-phase, consider the situation that different charge power causes charging current continuous and interrupted, the time-domain expression of derivation electric automobile battery charger alternating current;

According to charging current under two kinds of mode of operations of gained, build three-phase charger Harmonic coupling admittance matrix, wherein, it is equal to current harmonics number of times value time unequal that the element in described admittance matrix comprises terminal voltage harmonic number;

Combined with the voltage of charger by described time domain alternating current, propose the defining method of model parameter, this model considers the coupling of charger terminal voltage and harmonic current, and the element in its admittance matrix does not change with charger harmonic voltage;

According to described calculation method of parameters, in conjunction with constructed by coupling admittance matrix, set up the harmonic-model of three-phase charger of electric vehicle.

As a preferred embodiment of the present invention, according to the uncontrollable bridge rectifier equivalent electric circuit of described three-phase, the time-domain expression of derivation electric automobile battery charger alternating current comprises:

According to the uncontrollable bridge rectifier of described three-phase, there is twice charging process in every phase charging current in half cycles;

According to the operation principle of three-phase charger of electric vehicle, different charge power will cause charger operate in charging current intermittently with continuous two kinds of operating modes;

By described charging process, introduce [α ₁, δ ₁] and [α ₂, δ ₂] represent that the conducting that in half cycles, alternating current is interrupted is interval, consider that charge power increases and charging current will be caused continuous, described two conducting intervals are modified to [α ₁, δ ₂]; Wherein α ₁be the 1st the charging process angle of flow, δ ₁be the 1st charging process angle of cut-off, α ₂be the 2nd the charging process angle of flow, δ ₂2nd charging process angle of cut-off;

By DC side circuit equivalent, according to the terminal voltage condition that three-phase charger is given, the time-domain expression of alternating current under different operating condition of deriving.

As another kind of preferred version of the present invention, according to charging current under two kinds of mode of operations of gained, build three-phase charger Harmonic coupling admittance matrix and comprise:

The harmonic number of charger three-phase symmetrical terminal voltage is designated as h, and h=2n+1, n are integer; According to being that DC side is powered by the line voltage that AC is maximum during each conducting of the uncontrollable rectification circuit of three-phase, the harmonic number pushing away wire voltage is h ', h '=6m+1 and h '=6m '-1, m is integer, m ' is natural number;

The harmonic number of charger charging current is designated as k, k=6b+1 and k=6b '-1, b is integer, and b ' is natural number; Respectively according to whether h ' and k be equal charging current under two kinds of working models carried out to Fourier transform and is organized into matrix form, building corresponding Harmonic coupling admittance matrix.

As a modification of the present invention scheme, combined by described time domain alternating current with the voltage of charger, the defining method proposing model parameter comprises:

According to the uncontrollable rectification circuit of three-phase of given circuit parameter, angle corresponding when being 0 by three-phase charger charging current is defined as angle of cut-off δ _n(n=1,2 represent the 1st, 2 charging respectively), makes temporal current i accordingly _at ()=0 obtains corresponding parameter;

$i_a({\mathrm{\δ}}_n/\mathrm{\ω})=0\⇒{\mathrm{\δ}}_n$

Direct voltage after terminating according to the electric discharge of DC side filter capacitor is equal with line voltage during lower a pair diode current flow determines angle of flow α;

δ is met according to the uncontrollable rectification circuit of three-phase the 1st, 2 charging process angles of flow and angle of cut-off ₂=δ ₁+ π/3 and α ₁=α ₂-π/3, the parameter of charger harmonic-model when acquisition charging current is interrupted;

By the model parameter correction of charging current consecutive hours, according to the angle of flow of the intersection point determination electric current of line voltage, when considering current continuity, often pair of diode current flow scope is π/3, then δ ₂=α ₂+ π/3 and α ₁=α ₂-π/3, obtain the parameter of charging current consecutive hours charger harmonic-model.

As another kind of improvement project of the present invention, according to described calculation method of parameters, in conjunction with constructed by coupling admittance matrix, the harmonic-model setting up three-phase charger of electric vehicle comprises:

The Harmonic coupling admittance matrix model of described three-phase charger is noted by abridging;

$I_K=Y^{+}{U}_h+Y^{-}{U}_h^{*}$

Wherein: I _kfor AC harmonic current vector, U _hand U _h ^*for input harmonics voltage and conjugate vector thereof, Y ⁺and Y ^-be Harmonic coupling admittance matrix;

Described Harmonic coupling admittance matrix model considers the coupling of charger terminal voltage and harmonic current, and every order harmonics voltage all can cause the generation of individual harmonic current;

According to given three-phase charger terminal voltage condition, this Harmonic coupling admittance matrix model is utilized directly to obtain AC individual harmonic current by algebraic operation.

Compared with prior art, contemplated by the invention electric automobile battery charger discontinuous current and continuous print two kinds of mode of operations under different charge power, tool has the following advantages:

1, as DC side filter inductance L _fwhen being less than 14.3mH, under the two kinds of patterns adopting this model to calculate, the error of calculation of charger harmonic current is less than 10%, can obtain result comparatively accurately.

2, this Harmonic coupling admittance matrix model considers the coupling of charger terminal voltage and harmonic current, and every order harmonics voltage all can cause the generation of individual harmonic current; Matrix element does not change with it independent of charger harmonic voltage situation, only relevant with angle of cut-off with the angle of flow introduced.

3, the terminal voltage condition of given charger, directly can be calculated amplitude and the phase place of the individual harmonic current being injected into electrical network, calculate easy by this model.

4, this model is applied widely, for the nonlinear rectification load of three-phase, this modeling method all can be adopted to revise accordingly Harmonic coupling admittance matrix, to meet the demands.

5, this model is that the Harmonic characteristic analysis of three-phase charger of electric vehicle provides model foundation, is the basis of the total harmonic current decay of charging station and enlarge-effect analysis.

Accompanying drawing explanation

Fig. 1 is a kind of block diagram of modeling method of harmonic model of three-phase charger of electric vehicle;

Fig. 2 is three-phase charger of electric vehicle equivalent electric circuit time domain analysis block diagram;

Fig. 3 is the frequency-domain analysis block diagram of three-phase charger of electric vehicle.

Embodiment

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

A kind of modeling method of harmonic model of three-phase charger of electric vehicle, according to the uncontrollable bridge rectifier equivalent electric circuit of three-phase, the time-domain expression of derivation electric automobile battery charger alternating current, wherein, this electric current considers the situation that different charge power causes charging current continuous and interrupted, on this basis, Fourier transform is carried out to charging current under two kinds of mode of operations of gained, build three-phase charger Harmonic coupling admittance matrix, and this admittance matrix to comprise terminal voltage harmonic number equal to current harmonics number of times value time unequal, consider the combined-voltage of three-phase charger, the defining method of model parameter is proposed according to temporal current, in conjunction with constructed by coupling admittance matrix, set up the harmonic-model of three-phase charger of electric vehicle, model of the present invention considers the coupling of charger terminal voltage and harmonic current, its matrix element does not change with charger harmonic voltage, for analysis contains the charging station harmonic current of multiple stage charger with charger number of units, the variation characteristic of charge power provides good theoretical foundation, directly effectively can calculate the harmonic current of three-phase charger of electric vehicle.

Show a kind of flow chart of embodiment 1 of harmonic model of three-phase charger of electric vehicle with reference to Fig. 1, Fig. 1, described method can comprise:

Step 1: according to the uncontrollable bridge rectifier equivalent electric circuit of described three-phase, the time-domain expression of derivation electric automobile battery charger alternating current.

Wherein, described charging current expression formula considers the continuous and interrupted situation of charging current that different charge power causes.

It should be noted that, the uncontrollable rectification circuit of three-phase charger has capacitor charging, electric discharge two kinds of operating states, in the capacitor charging state in each cycle, the maximum line voltage of AC is that DC side is powered, and every phase charging current exists twice charging process in half cycles.Because in twice turn on process of half cycles when charger underloading or heavy duty, charging current there will be interrupted and continuous.By α ₁, α ₂and δ ₁, δ ₂be designated as conducting and the angle of cut-off of diode the 1st, 2 charging process in half cycles.Along with the increase of charge power, charging current by being intermittently changed to continuously, twice charging process in every half cycle just 1/4 the cycle place link up.

Seen from the above description α ₂> δ ₁and α ₂≤ δ ₁the condition of discontinuous current and continuous operation mode respectively.Obtain line voltage according to known charger three-phase symmetrical terminal voltage, by DC side load equivalent, obtain the time-domain expression of charger electric current.

With i _afor example, in every half cycles, the conducting interval of charging current is designated as: the 1st charging conducting interval [α ₁, δ ₁] and [α ₁+ π, δ ₁+ π], the conducting interval [α of the 2nd charging ₂, δ ₂] and [α ₂+ π, δ ₂+ π].Actual electric network voltage comprises some odd harmonic components, if the AC terminal voltage of charger is,

In formula: h=2n+1, n be integer (h=1,3,5 ... be odd harmonic number of times), U _hwith for h subharmonic voltage effective value and phase place, H is the ceiling voltage harmonic number of research, and m=1,2,3 represent a respectively, b, c three-phase.

1st charging conducting interval [α ₁, δ ₁] and [α ₁+ π, δ ₁+ π] in, line voltage u _abfor DC side is powered; 2nd charging conducting interval [α ₂, δ ₂] and [α ₂+ π, δ ₂+ π] in, line voltage u _acfor DC side is powered, by DC side load equivalent, the time-domain expression of derivation charger electric current is,

1), when charging current is interrupted, alternating current is expressed formula and is:

In formula: U _hwith for charger terminal voltage effective value and phase place, G _hand θ _hfor amplitude and the phase place of DC side equivalent admittance.

2) charging current is continuous

Charging current consecutive hours i _aexpression formula constant, but its alternating current conducting interval is [α ₁, δ ₂] and [α ₁+ π, δ ₂+ π].

Step 2: according to charging current under two kinds of mode of operations of gained, builds three-phase charger Harmonic coupling admittance matrix.

Wherein, it is equal to current harmonics number of times value time unequal that described admittance matrix element comprises terminal voltage harmonic number.

It should be noted that, the uncontrollable rectification circuit of three-phase bridge only contains k=1, and 5,7 ... (k=6b+1 and k=6b '-1, b is integer, b ' is natural number) secondary current harmonics, and number of times h '=1 of line voltage, 5,7,11,13....(h '=6m+1 and h '=6m '-1, m is integer, m ' is natural number) be odd number, thus h ' ± k is even number.Whether equal with k for h ', by a phase current i _at () be fourier expansion in one-period, obtain its k primary current harmonic phasor for,

${\stackrel{\·}{I}}_{\mathrm{ak}}=\frac{\sqrt{2}}{T}{\∫}_0^T{i}_a\left(t\right)e^{-\mathrm{jk\ωt}}\mathrm{dt}$

As h ≠ k, k primary current harmonic wave is,

As h=k, k primary current harmonic wave is,

1) coupling admittance matrix

By described I _akbe organized into matrix form,

2) matrix element:

1. matrix element when charging current is interrupted

$Y_{k,h}^{+}=\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{j(\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}\frac{e^{j(h-k){\mathrm{\δ}}_1}-e^{j(h-k){\mathrm{\α}}_1}}{j(h-k)}+\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{j(-\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}\frac{e^{j(h-k){\mathrm{\δ}}_2}-e^{j(h-k){\mathrm{\α}}_2}}{j(h-k)},h\≠k$

$Y_{k,h}^{+}=\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{j(\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}({\mathrm{\δ}}_1-{\mathrm{\α}}_1)+\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{j(-\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}({\mathrm{\δ}}_2-{\mathrm{\α}}_2),h=k$

$Y_{k,h}^{-}=-\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{-j(\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}\frac{e^{-j(h+k){\mathrm{\δ}}_1}-e^{-j(h+k){\mathrm{\α}}_1}}{j(h-k)}-\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{-j(-\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}\frac{e^{-j(j+k){\mathrm{\δ}}_2}-e^{-j(h+k){\mathrm{\α}}_2}}{j(h+k)}$

In formula: r=1 (h=1,7,13 ...) and-1 (h=5,11,17 ...), subscript+,-represent and voltage, admittance matrix element that voltage conjugation is relevant.

2. the matrix element of charging current consecutive hours

$Y_{k,h}^{+}=\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{j(\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}\frac{e^{j(h-k){\mathrm{\α}}_2}-e^{j(h-k){\mathrm{\α}}_1}}{j(h-k)}+\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{j(-\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}\frac{e^{j(j-k){\mathrm{\δ}}_2}-e^{j(h-k){\mathrm{\α}}_2}}{j(h-k)},h\≠k$

$Y_{k,h}^{+}=\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{j(\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}({\mathrm{\α}}_2-{\mathrm{\α}}_1)+\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{j(-\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}({\mathrm{\δ}}_2-{\mathrm{\α}}_2),h=k$

$Y_{k,h}^{-}=-\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{-j(\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}\frac{e^{-j(h+k){\mathrm{\α}}_2}-e^{-j(h+k){\mathrm{\α}}_1}}{j(h+k)}-\frac{\sqrt{3}{G}_h}{\mathrm{\π}}{e}^{-j(-\frac{\mathrm{\π}}{6}r+{\mathrm{\θ}}_h)}\frac{e^{-j(j+k){\mathrm{\δ}}_2}-e^{-j(h+k){\mathrm{\α}}_2}}{j(h+k)}$

Step 3: combined with the voltage of charger by described time domain alternating current, proposes model

Determination method for parameter.

Wherein, described model considers the interrupted and continuous print situation of charging current.

It should be noted that, the maximum pass range of each charging process of the uncontrollable rectification circuit of three-phase is π/3, and in addition, the intersection point of charging current consecutive hours line current determines the corresponding angle of flow and the angle of cut-off in its conducting interval.

1) charging current is interrupted

1. angle of cut-off δ ₁and δ ₂: in conducting interval, angle corresponding when capacitance charging current is 0 is angle of cut-off.

$i_a({\mathrm{\δ}}_n/\mathrm{\ω})=0\⇒{\mathrm{\δ}}_n$ Namely by i _a(δ _n/ ω)=0 derive δ _n;

In formula: n=1,2 represent the 1st, 2 charging process respectively.

2. angle of flow α ₁and α ₂: terminate rear direct voltage U according to capacitor discharge _dcequally with line voltage during lower a pair diode current flow determine the angle of flow.With angle of flow α ₂for example,

$u_{\mathrm{ab}}({\mathrm{\δ}}_1/\mathrm{\ω})e^{-({\mathrm{\α}}_2-{\mathrm{\δ}}_1)/\left(\mathrm{\ωRC}\right)}=u_{\mathrm{ac}}({\mathrm{\α}}_2/\mathrm{\ω})\⇒{\mathrm{\α}}_2$

Also δ is met for the uncontrollable rectification circuit of three-phase the 1st, 2 charging process angles of flow and angle of cut-off ₂=δ ₁+ π/3 and α ₁=α ₂-π/3, can obtain accordingly charging current interrupted time charger harmonic-model parameter.

2) charging current is continuous

Charging current consecutive hours can be directly interval by the conducting of the intersection point determination electric current of line voltage,

$u_{\mathrm{ab}}({\mathrm{\α}}_2/\mathrm{\ω})=u_{\mathrm{ac}}({\mathrm{\α}}_2/\mathrm{\ω})\⇒{\mathrm{\α}}_2$

Because now often pair of diode current flow scope is π/3, then δ ₂=α ₂+ π/3 and α ₁=α ₂-π/3, can obtain the parameter of charging current consecutive hours charger harmonic-model accordingly.

Step 4: according to described calculation method of parameters, in conjunction with constructed by coupling admittance matrix, set up the harmonic-model of three-phase charger of electric vehicle.

Described Harmonic coupling admittance matrix is combined with model parameter calculation, is the Harmonic coupling admittance matrix model of three-phase charger of electric vehicle:

$I_K=Y^{+}{U}_h+Y^{-}{U}_h^{*}$

In formula: I _kfor AC harmonic current vector, U _hand U _h ^*for input harmonics voltage and conjugate vector thereof, Y ⁺and Y ^-be Harmonic coupling admittance matrix.

It should be noted that, the harmonic-model of described three-phase charger of electric vehicle considers the interrupted and continuous print situation of charging current, charger terminal voltage and individual harmonic current are coupled together, matrix element does not change with it independent of terminal voltage, the terminal voltage of given electric automobile battery charger, directly effectively can calculate electric automobile battery charger under different charge power by this Harmonic coupling admittance matrix model and inject the individual harmonic current I of electrical network _k(k is current harmonics number of times, k=1,5,7 ...).

Show a kind of time domain analysis schematic diagram of three-phase charger of electric vehicle equivalent electric circuit with reference to Fig. 2, Fig. 2, can comprise:

Step 1: according to the equivalent electric circuit of three-phase charger of electric vehicle, given charger terminal voltage condition.

Wherein, described charger terminal voltage comprises odd harmonic.

Step 2: terminal voltage can be generated pulsating dc voltage in charger DC capacitor side after rectifier.

Wherein, described direct voltage is pulsed six times in a cycle, and the waveform of each pulsation is all the same.

Step 3: described direct voltage is acted on load and produce direct current, then be coupled with AC network through rectifier.

Step 4: according to the coupling of described alternating current-direct current side, causes rectifier alternating current generation harmonic distortion.

Show a kind of frequency-domain analysis schematic diagram of three-phase charger of electric vehicle with reference to Fig. 3, Fig. 3, can comprise:

Step 1: according to the equivalent electric circuit of three-phase charger of electric vehicle, given charger terminal voltage condition.

Step 2: according to described modeling method, build the Harmonic coupling admittance matrix of charger, Confirming model parameter, sets up the harmonic-model of three-phase charger of electric vehicle.

Step 3: amplitude and the phase place that described terminal voltage conditioning directly can be obtained the individual harmonic current of charger AC in this model.

Wherein, according to described charger terminal voltage and harmonic-model, individual harmonic current is tried to achieve by algebraic operation.

Inject except the harmonic current of electrical network except effectively calculating charger, described model is that the harmonic characterisitic analyzing three-phase charger of electric vehicle provides model foundation, can carry out quantitative analysis better to the total harmonic current decay of charging station and enlarge-effect.

What finally illustrate is, above embodiment is only in order to illustrate technical scheme of the present invention and unrestricted, although with reference to preferred embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that, can modify to technical scheme of the present invention or equivalent replacement, and not departing from aim and the scope of technical solution of the present invention, it all should be encompassed in the middle of right of the present invention.

Claims (3)

1. the modeling method of a harmonic model of three-phase charger of electric vehicle, it is characterized in that, twice turn on process is there is in each diode according to three-phase uncontrollable bridge rectifier equivalent electric circuit in half cycles, consider two kinds of mode of operation situations that different charge power causes charging current continuous and interrupted, the time-domain expression of derivation electric automobile battery charger alternating current;

According to charging current under two kinds of mode of operations of gained, build three-phase charger Harmonic coupling admittance matrix, wherein, it is equal to current harmonics number of times value time unequal that the element in described admittance matrix comprises terminal voltage harmonic number;

Combined with the voltage of charger by described time domain alternating current, propose the defining method of model parameter, this model considers the coupling of charger terminal voltage and harmonic current, and the element in its admittance matrix with the change of charger harmonic voltage, not comprising:

According to the uncontrollable rectification circuit of three-phase of given circuit parameter, angle corresponding when being 0 by three-phase charger charging current is defined as angle of cut-off δ _n, wherein n=1,2 represent the 1st, 2 charging respectively; Accordingly, temporal current i is made _at ()=0 obtains corresponding parameter;

$i_a({\mathrm{\δ}}_n/\mathrm{\ω})=0\⇒{\mathrm{\δ}}_n$

In formula: ω is the specified angular frequency of electrical network;

Direct voltage after terminating according to the electric discharge of DC side filter capacitor is equal with line voltage during lower a pair diode current flow determines angle of flow α;

δ is met respectively according to the uncontrollable rectification circuit of three-phase the 1st, 2 charging process angles of flow and angle of cut-off ₂=δ ₁+ π/3 and α ₁=α ₂-π/3, accordingly, the parameter of charger harmonic-model when acquisition charging current is interrupted;

By the model parameter correction of charging current consecutive hours, according to line voltage u _aband u _acthe angle of flow α of intersection point determination electric current ₂, when considering current continuity, often pair of diode current flow scope is π/3, then δ ₂=α ₂+ π/3 and α ₁=α ₂-π/3, accordingly, obtain the parameter of charging current consecutive hours charger harmonic-model;

According to described calculation method of parameters, in conjunction with constructed by coupling admittance matrix, set up the harmonic-model of three-phase charger of electric vehicle;

The Harmonic coupling admittance matrix model of described three-phase charger is noted by abridging;

$I_k=Y^{+}{U}_h+Y^{-}{U}_h^{*}$

Wherein: I _kfor AC harmonic current vector, U _hand U _h ^*for input harmonics voltage and conjugate vector thereof, Y ⁺and Y ^-be Harmonic coupling admittance matrix;

Described Harmonic coupling admittance matrix model considers the coupling of charger terminal voltage and harmonic current, and every order harmonics voltage all can cause the generation of individual harmonic current;

According to given three-phase charger terminal voltage condition, this Harmonic coupling admittance matrix model is utilized directly to obtain AC individual harmonic current by algebraic operation.

2. the modeling method of a kind of harmonic model of three-phase charger of electric vehicle according to claim 1, is characterized in that: according to the uncontrollable bridge rectifier equivalent electric circuit of described three-phase, the time-domain expression of derivation electric automobile battery charger alternating current comprises:

According to the uncontrollable bridge rectifier of described three-phase, there is twice charging process in every phase charging current in half cycles;

According to the operation principle of three-phase charger of electric vehicle, different charge power will cause charger operate in charging current intermittently with continuous two kinds of operating modes;

By described charging process, introduce [α ₁, δ ₁] and [α ₂, δ ₂] represent that the conducting that in half cycles, alternating current is interrupted is interval, consider that charge power increases and charging current will be caused continuous, described two conducting intervals are modified to [α ₁, δ ₂]; Wherein α ₁be the 1st the charging process angle of flow, δ ₁be the 1st charging process angle of cut-off, α ₂be the 2nd the charging process angle of flow, δ ₂2nd charging process angle of cut-off;

By DC side circuit equivalent, according to the terminal voltage condition that three-phase charger is given, the time-domain expression of alternating current under different operating condition of deriving.

3. the modeling method of a kind of harmonic model of three-phase charger of electric vehicle according to claim 1, is characterized in that: according to charging current under two kinds of mode of operations of gained, builds three-phase charger Harmonic coupling admittance matrix and comprises:

The harmonic number of charger three-phase symmetrical terminal voltage is designated as h, and h=2n+1, n are integer; According to being that DC side is powered by the line voltage that AC is maximum during each conducting of the uncontrollable rectification circuit of three-phase, the harmonic number pushing away wire voltage is h ', h '=6m+1 and h '=6m '-1, m is integer, m ' is natural number;

The harmonic number of charger charging current is designated as k, k=6b+1 and k=6b '-1, b is integer, and b ' is natural number; Respectively according to whether h ' and k be equal charging current under two kinds of working models carried out to Fourier transform and is organized into matrix form, building corresponding Harmonic coupling admittance matrix.