CN106374596A - Non-isolation type three-phase three-level V2G charge-discharge topological structure and control method therefor - Google Patents

Abstract

The invention discloses a non-isolation type three-phase three-level V2G charge-discharge topological structure. The non-isolation type three-phase three-level V2G charge-discharge topological structure comprises a main circuit module and a control circuit module, wherein the main circuit module comprises three parts in cascading manner, including a DC/DC part, an H bridge balance circuit and a DC/AC part; a vehicle-mounted power battery is connected to a direct current positive bus and a direct current negative bus through a bidirectional half-bridge converter; the H bridge balance circuit and two voltage-division capacitors C1 and C2 are arranged between the direct current positive bus and the direct current negative bus, and the direct current positive bus and the direct current negative bus are connected with the output end of the bidirectional half-bridge converter in parallel; the direct current buses are connected with a diode clamping type three-level PWM converter; a three-phase alternating current power supply live wire is connected to connecting places of upper and lower bridge arms of each phase of the bridge arms through a three-phase LC filter; the direct current buses are positioned in the H bridge balance circuit; according to the H bridge balance circuit, an IGBT switch tube Tb1 is in anti-parallel connection with a rapid recovery diode, or the switch tube Tb1 with an in-vivo parasitic diode is connected with a one-way conducive free-wheeling diode Db1 in series to form one side bridge arm, and a balance inductor Lb1 is connected in the middle thereof; the other end of the balance inductor is connected to a direct current side middle point; the bridge arms on the two sides are connected with a shared negative electrode and a shared positive electrode; and namely, the upper ends of the bridge arms are both connected to the direct current positive bus while the lower ends of the bridge arms are both connected to the direct current negative bus.

Description

A kind of non-isolation type three-phase tri-level v2g discharge and recharge topological structure and its control method

Technical field

The invention belongs to applied power electronics technical field, particularly to a kind of non-isolation type three-phase tri-level v2g charge and discharge Electric topological structure and its control method.Specifically under modern electric converter technique, it is suitable for distributed power source and AC network Realize energetic interaction, meet the non-isolation type v2g system topological of common-mode voltage suppression and neutral-point potential balance Collaborative Control demand Structure and control method.

Background technology

In the face of increasingly serious energy crisis, promote the development of ev industry, realize the two-way energy of vehicle and electrical network Amount interactive (vehicle-to-grid, v2g) has become trend of the times.The development of v2g technology tends to integrated at present.BYD The existing all kinds of external chargers of two-way contravariant discharge and recharge technological innovation, are directly integrated in electric machine controller, and being similar to will Whole charging cabinet reduces puts car into, realizes alternating current large-power and charges, the unidirectional current in battery reversely can be become alternating current again Realize electric discharge.The two-way contravariant multi-function motor controller of certain company's recent development domestic also achieves same function.

The integrated cascade structure having benefited from non-isolation type of v2g charge-discharge system.Two-way pwm changer is arranged in pairs or groups with two-way Half-bridge converter, eliminates the Industrial Frequency Transformer of heaviness or the high frequency transformer of complexity, while simplied system structure, effectively Improve inversion efficiency and power density.On the one hand, bi-directional half bridge topology is simple and practical, and energy conversion efficiency is high, switch element The voltage bearing, current stress are little with diode.On the other hand, cascade structure can be with effectively utilizes prime booster circuit to power Cell output voltage is boosted, stabilize the fluctuation of electrokinetic cell output voltage it is ensured that rear class inverter ac grid-connected to direct current The demand of busbar voltage.But non-isolation type v2g topological structure lacks direct electrical isolation due to vehicle mounted dynamic battery and electrical network, The common mode current being formed can increase grid current harmonic wave, or even brings potential safety hazard, also can affect the normal use of equipment, accelerates Ageing equipment.In the integrated charging/discharging apparatus that certain company develops at it, take the lead in filling technology soon using exchange, three-phase charge and discharge is High-power up to 40kw, much larger than the 3kw power level of traditional Vehicular charger.Although this achievement can be to existing industry standard Bring certain impact with specification, but the development trend following because there is disclosed industry, there is reasonability and the advance of its own.Cause , it is considered to the future in engineering applications of v2g technology high-power, suppression common mode electric current is for the development of non-isolation type v2g system for this More seem most important with safe handling.

Common mode current suppression is the key problem in technology that non-isolated v2g integrated system practical application needs to solve.From existing document See, the common mode current suppression approach being proposed substantially can be divided into: increase common mode impedance loop and improve modulation strategy two big class.Its In, increase common mode impedance loop and can be divided into increase common-mode voltage wave filter again, change common mode loop topology, circuit parameter coupling etc. Various ways, to realize common mode current shunting whereby.Or change common mode impedance loop, wherein, approach increases for a moment in various degree The number of devices of adding system and switching loss, but dependable performance, can simplify control strategy；Approach two by change modulation system Lai The common-mode voltage of reduction system, thus reducing the voltage pulsation in photovoltaic parasitic capacitance, reaching the purpose of suppression electric current, agreeing with non- Isolation structure is simply pursued to high power density and structure.

Neutral-point potential balance is the intrinsic problem of tri-level circuit, as the voltage reference points of whole system, midpoint potential Skew go to cause the common-mode voltage of system output to fluctuate for a moment, be further exacerbated by the harm of common-mode voltage.Solve problem Thinking be mostly to control neutral-point potential balance the action time changing positive and negative small vector from different angles.On the other hand, just Negative small vector simultaneously participates in the synthesis of reference vector, and system output common mode voltage can be led to have larger amplitude, therefore at present again It is difficult to find a kind of method that can take into account neutral-point-potential balance control and common-mode voltage suppression.

Content of the invention

The purpose of the present invention is to propose to a kind of topological structure of non-isolation type three-phase tri-level v2g system and its supporting control Method processed, meeting under high-power trend, non-isolated v2g integrated system is to common-mode voltage suppression and neutral-point potential balance Technical need.

The purpose of the present invention is achieved through the following technical solutions.

A kind of non-isolation type three-phase tri-level v2g discharge and recharge topological structure, including main circuit module and control circuit module, Wherein:

Described main circuit module, is made up of three part cascades, is dc/dc part (using bi-directional half bridge changer), h respectively Bridge balancing circuitry and dc/ac part (using diode-clamped three level pwm changer).Vehicle mounted dynamic battery (group) is through two-way Half-bridge converter, connects to direct current positive and negative busbar, is provided with h bridge balancing circuitry and two derided capacitors c between direct current positive and negative busbar₁ And c₂, it is in parallel with the outfan of bi-directional half bridge changer, meanwhile, dc bus connects diode-clamped three level pwm and becomes Parallel operation, three-phase alternating-current supply live wire accesses the upper and lower bridge arm junction of each phase brachium pontis through three-phase lc wave filter；Described dc bus Place's h bridge balancing circuitry, its h bridge balancing circuitry is by igbt switching tube t_b1Inverse parallel fast recovery diode (or there is endobiosis two The switching tube t of pole pipe_b1) and one-way conduction fly-wheel diode d_b1Series connection, constitutes side brachium pontis, connects balance inductance l in the middle of it_b1, The other end of balance inductance accesses DC side midpoint, both sides brachium pontis, and common cathode, common-anode connect, and that is, upper end is just all being connected to direct current Bus, lower end is all connected to direct current negative busbar, its role is to, and can select balancing circuitry according to the offset direction of midpoint potential Mode of operation.By adjusting electric capacity c₁And c₂The quantity of electric charge being carried, thus control the skew of midpoint potential；

Described control circuit module, including sector judge module, basic vector selecting module, output order optimization module and Svpwm generation module.

Further, the operation mode 1 of described h bridge balancing circuitry: DC side collection derided capacitors c₁And c₂Output voltage letter Number u_dc1And u_dc2, as u in circuit_dc1<u_dc2When, midpoint potential is higher, controls h bridge balancing circuitry to be operated in buck chopper mode, Switching tube t_b1Work, t_b2Disconnect, switching tube t_b1Conducting, electric current from dc bus out, flows successively through derided capacitors c₁, balance Inductance l_b1, switching tube t_b1, return to DC side through system front stage circuits dc/dc part anti-paralleled diode, make inductance l_b1Energy storage, As switching tube t_b1During shutoff, electric current is through balance inductance l_b1, diode d_b1With derided capacitors c₁Form loop, be stored in inductance l_b1On electric energy be recycled to dc bus, make midpoint potential reduce, until and c₂The voltage at two ends reaches in certain scope Balance；The operation mode 2 of described h bridge balancing circuitry: as u in circuit_dc1>u_dc2When, midpoint potential is low, controls h bridge balance electricity Road is operated in boost chopper mode, switching tube t_b2Work, t_b1Disconnect, switching tube t_b2Conducting, electric current flows out from dc bus, according to Secondary flow through switching tube t_b2, balance inductance l_b2, derided capacitors c₂, return to through system front stage circuits dc/dc part anti-paralleled diode DC side, to electric capacity c₂Charge, and make inductance l_b2Energy storage, as switching tube t_b2When shutoff, electric current is through balance inductance l_b2, derided capacitors c₂With diode d_b2Form loop, be stored in inductance l_b2On electric energy transfer to c₂On, make midpoint potential liter Height, until and c₁The voltage at two ends reaches balance in certain scope.

The control method of above-mentioned non-isolation type three-phase tri-level v2g discharge and recharge topological structure, has common-mode voltage suppression work( Can, voltage on line side current sample module extracts three phase network electromotive force signal e_a,e_b,e_cWith three-phase current on line side signal i_a,i_b, i_c, through voltage and current double closed-loop (outer voltage and current inner loop) module, generate reference voltage vector, send into control circuit mould Block, specifically comprises the following steps that

(1) determine big sector and little sector residing for reference vector, when selecting basic vector, reject output common mode voltage amplitude It is worth larger (>=u_dc/ 3) basic vector, in little sector that selection reference vector is located, distance reference vector is nearest and output common mode is electric Pressure amplitude value≤u_dc/ 6 three basic vector state synthesized reference vectors；

(2) determine the output order of three basic vector states, svm sends out ripple mode using five-part form, every time with positive small vector As start vector.Taking the first sector as a example, the output order of 1 and 2 little sector basic vectors is:

poo→ooo→oon→ooo→poo.The output order of 3 and 4 little sector basic vectors is:

poo→pon→oon→pon→poo；The output order of 5 little sector basic vectors is:

poo→pon→pnn→pon→poo；Every phase on off state is not in each switch periods by the saltus step of p to n Interior, have one mutually to switch and be failure to actuate, total switch switching times are 4 times；

(3) it is to ensure that reference vector, when changing sector (such as by 5 little Sector Transition to 6 little sectors), at most has one mutually to open Pass action, 6 little sectors, still using positive small vector as start vector, adopt asymmetric vector composite analysis simultaneously, pon → oon → Pon → ppn → pon, total switch switching times are similarly 4 times；

(4) other sector vector output order are analogized in accordance with the law.

The invention has the beneficial effects as follows: a kind of New Topological knot of non-isolation type three-phase tri-level v2g integrated system is proposed Structure and its supporting control method are it is achieved that non-isolated v2g integrated system common-mode voltage suppresses collaborative with neutral-point potential balance Control, filled up the blank in this field.Propose five-part form de-redundancy svm control strategy, propose output common mode voltage magnitude relatively Big redundancy small vector, fundamentally ensure that the inhibition of system common-mode voltage, basic vector output order is entered simultaneously Gone optimization it is ensured that reference vector, when changing sector, at most has a phase switch motion, thus suppressing the common mode electricity of amplitude Pressure spike.Meanwhile, after optimization, switch switching times are as little as possible, decrease switching loss；For coordinating above-mentioned control method, Realize the Collaborative Control of neutral-point potential balance simultaneously, devise the novel topological structure of v2g system: introduce at dc bus H bridge balancing circuitry (or single bridge arm balance circuit equivalent therewith), and give the concrete structure of system topological and the detailed of parameter Thin method for designing.Novel topological structure can be effectively ensured the balance of midpoint potential, have stronger reliability and robustness, be The suppression of common-mode voltage provides strong guarantee and support.It is achieved thereby that common-mode voltage suppression and neutral-point potential balance Collaborative Control, improves the Electro Magnetic Compatibility of system, ensure that energy in bidirectional flow characteristic and the unit power of v2g system simultaneously Factor, low harmony wave run.

Brief description

Fig. 1 is non-isolation type three-phase tri-level v2g system topology figure of the present invention.

Fig. 2 is non-isolated v2g system common-mode equivalent model schematic diagram.

Fig. 3 is DC side common mode equivalent model schematic.

Fig. 4 is AC common mode simplified model schematic diagram.

Fig. 5 is the svpwm modulation figure based on double-closed-loop control.

Fig. 6 is three level space voltage vector-diagrams.

Fig. 7 is spatiality vectogram.

Fig. 8 is selected basic vector figure after de-redundancy.

Fig. 9 is h bridge balancing circuitry topological diagram.

Figure 10 is applied to non-isolated v2g system diagram for h bridge balancing circuitry topology.

Figure 11 is single bridge arm balance circuit topology figure.

Figure 12 is that single bridge arm balance circuit topology is applied to non-isolated v2g system diagram.

Figure 13 flows through the map of current of balance inductance for h bridge circuit when working.

Specific embodiment

Below in conjunction with the accompanying drawings, the present invention is described in more detail.

Fig. 1 show the application non-isolation type three-phase tri-level v2g system topology figure.Described topological structure is applied to High frequency integrated v2g system, is vehicle mounted dynamic battery group, dc/dc part, DC side electric capacity of voltage regulation, dc/ac from left to right successively Partly, lc wave filter, electrical network, topological structure main body is made up of dc/dc part and dc/ac part two-layer configuration, described dc/dc portion Bi-directional half bridge changer use in sorting, dc/ac part from diode-clamped three level pwm changer, so configured topology Structure, it is possible to achieve the two-way flow of energy, that is, energy on-vehicle battery side can be flowed to by grid side, electrical network fills for electric automobile Electricity；Can also be from on-vehicle battery effluent to grid side, electric automobile is to electrical network back discharge.

Resolving ideas: the presence of common-mode voltage necessarily encourages common mode current, the property of common mode current by common-mode voltage and is returned Roadlock is anti-to be together decided on.In non-isolation type v2g cascade circuit, the high frequency change of switching device is the basic of common-mode effect generation Reason, sets up the key that common mode equivalent circuit is analysis common mode problem.Fig. 2, Fig. 3 and Fig. 4 enter to the common mode equivalent circuit of system Row analysis, the property of each point common-mode voltage in research and analysis v2g system.

In common mode equivalent circuit, DC bus capacitor c₁And c₂Presence it is achieved that the nature solution of DC side and AC Coupling, therefore, parasitic capacitance c_pvThe voltage at two ends, that is, the common-mode voltage of system is actual is DC side and AC two parts are contributed Superposition, for AC: had according to Kirchhoff's law:

$\left\{\begin{array}{c}{u}_{aq}={\mathrm{ri}}_a+l\frac{{\mathrm{di}}_a}{dt}+u_{cm1}\\ u_{bq}={\mathrm{ri}}_b+l\frac{{\mathrm{di}}_b}{dt}+u_{cm1}\\ u_{cq}={\mathrm{ri}}_c+l\frac{{\mathrm{di}}_c}{dt}+u_{cm1}\end{array}\right.---\left(1\right)$

Three equations in formula are added and, obtain:

$u_{cm1}=\frac{u_{aq}+u_{bq}+u_{cq}}{3}---\left(2\right)$

For DC side:

$u_{cm2}=\frac{c_{smp}}{c_{smp}+c_{pv}}{u}_{nq}---\left(3\right)$

About the explanation of symbol in formula: common reference point cut-off stream negative busbar (being designated as q), current transformer outfan a, b, c, N is designated as u respectively to the voltage of reference point q_aq、u_bq、u_cqAnd u_nq；L comprises pwm current transformer output inductor and line impedance, r For line resistance；u_cm1Represent AC common-mode voltage；c_smpThe parasitism to car body (including over the ground) for the representation switch device output end Electric capacity.

The total common-mode voltage of system is equal to the contribution sum of AC and DC side, u_cm=u_cm1+u_cm2.Motor driven systems Required power is larger, needs more power monomer to carry out connection in series-parallel.Larger monomer surface is amassed and is led to parasitic capacitance c_inValue Larger, typically in nf level；And the silicone grease between switching device and fin, its dielectric constant is more than vacuum, the face of switching device Amass less, therefore c_smpCapacitance less, typically in pf level.To sum up u_cm2It is less than ± 1v, i.e. the contribution of DC side can be ignored.

The amplitude of common-mode voltage and frequency are determined by DC bus-bar voltage and modulation strategy.The present invention is from svm modulation strategy Start with, based on non-isolation type v2g system topological, inquire into and meet the control strategy that common-mode voltage suppression requires.

The specific embodiment of control strategy:

The logical relation of control strategy is as shown in Figure 5.Describe in detail as follows: set three phase network electromotive force as e_a,e_b,e_c, warp Three-phase linear inductance l accesses the upper underarm junction of each phase brachium pontis, and three-phase current on line side is respectively i_a,i_b,i_c, ac/dc part adopts With the double-closed-loop control structure of outer voltage and current inner loop, obtain reference voltage vector signal through two close cycles, send into svpwm control Molding block, generates 12 tunnels and controls pulse, give ac/dc part 12 switching tubes, the control strategy of the present invention is to be directed to (the svpwm signal generation module see in Fig. 5) that svpwm control module proposes.

From fig. 6, it can be seen that showing 27 groups of on off states, orderly monogram with the alphabetical in order combination table that p, o and n are constituted In three letters represent the output level of a, b, c three-phase respectively.For example: the p in pnn represent a phase output level, first N represents the level of b phase output, and second n represents the level of c phase output.27 groups of on off states of three-level inverter are actual corresponding Only 19 voltage vectors, these vectors are known as the basic voltage vectors of three-level inverter.This 19 fundamental voltage arrows Amount spatially constitutes a planar regular hexagonal, and regular hexagon contains 36 little trianglees, the top of each little triangle Point represents a vector, and some of which vector represents multiple switch state.19 basic voltage vectors of in figure use v respectively₀ ～v₁₈Represent, 19 basic voltage vectors are divided into four classes, are followed successively by by the big I according to its mould length: big vector, middle vector, little Vector zero vector.The mould length of big vector is the longest, positioned at orthohexagonal six summits, the v in Fig. 6₁₃～v₁₈, have 6； The mould length of middle vector is taken second place, the v on the angular bisector of big triangle, in Fig. 6₇～v₁₂, have 6；The mould of small vector is long For the half of big Vector Mode length, internally positioned hexagonal summit, the v in Fig. 6₁～v₆, have 6, each small vector corresponding two Group on off state, referred to as positive small vector and negative small vector；The mould a length of zero of zero vector, the v in initial point, Fig. 6₀, correspond to Three groups of on off states.Regular hexagon is divided into six sectors by six big vectors, referred to as one, orthohexagonal every 60 degree of regions fan Area, 0～60 degree of referred to as first sector, the rest may be inferred for other sectors.

Each big sector is further divided into 6 zonules, zonule numbering is as shown in Figure 7.In vector space, Each basic vector and its corresponding common-mode voltage are shown in Table 1.Traditional three level svm algorithms, when choosing basic vector, cover institute 19 vectors having, by table 1 it is seen that, lead to the common-mode voltage amplitude of system reality output to be up to u_dc/3.

Table 1 basic vector state and corresponding common-mode voltage

By judging big sector and the zonule residing for reference vector, in the present invention select output common mode voltage magnitude≤ u_dc/ 6 vector state synthesized reference vector.Namely when selecting basic vector, give up the corresponding basic arrow of four row after in table 1 Amount.Fig. 8 taking the first sector as a example, illustrates and gives up common-mode voltage amplitude equal to u_dcSelected basic after/3 redundancy small vector Vector.Traditional seven segmentations send out the paired appearance that ripple mode depends on redundancy small vector, and therefore, seven segmentations are not suitable for rejecting redundancy Vector control method after small vector.In the present invention, svm sends out ripple mode using five-part form, defines five-part form de-redundancy svm and calculates Method.

So, the common-mode voltage amplitude maximum (u that non-isolated v2g system produces_dc/ 6) calculate than traditional three level svm Method (u_dc/ 3) decrease half, effective suppression common mode voltage amplitude, high-frequency pulsation.In synthesis v_refVector select on, Inventive algorithm is identical with traditional suppression common mode voltage svm algorithm, except that, optimize on off state herein further and turn Change order.

Compared to traditional suppression common mode voltage svm algorithm, five-part form de-redundancy svm algorithm every time using positive small vector as rise Beginning vector.Ensure that reference vector, when changing sector, at most has a phase switch motion (can realize " seamless in the little sector of 1-5 Switching ", that is, threephase switch is all not required to action), thus suppressing the common-mode voltage spike of amplitude.Meanwhile, on off state is cut Change and carry out between neighbouring vectors state, every time an only phase switch motion, effectively prevent traditional suppression common mode voltage in table 4 Svm algorithm is by-u_dc/ 6 arrive u_dc/ 6 saltus step；After optimization, switch switching times are as little as possible, to reduce switching loss, as table 4 institute Show, in 5 little sectors, on-off times are reduced to 4 times by 6 times.

It is noted that following above-mentioned optimization principles, in order to obtain preferable effect, 6 little sectors adopt asymmetric arrow Amount synthetic method, with respect to table 2 algorithm, on-off times is reduced to 4 times by 6 times.Meanwhile, started with middle vector pon, rather than Negative small vector oon, effectively prevent vector mutation when reference vector sector changes, and concrete switch state order is shown in Table 3 Shown.

Traditional suppression common mode voltage svm switch state table (i sector) of table 2

3 five sections of de-redundancy modulation switch State Transferring sequence list (i sector) of table

Taking the first sector 5 zonule as a example, under analysis conventional suppression common mode voltage svm modulation and the modulation of five-part form de-redundancy Common-mode voltage variation and switch switching times, concrete outcome is shown in Table 4:

Table 4 and the comparison of traditional suppression common mode voltage svm algorithm

From the point of view of above-mentioned analysis, the maximum of output common mode voltage magnitude is preferably limited by five-part form de-redundancy algorithm In u_dc/ 6, can effectively reduce the negative effect that common-mode voltage brings.

Job analysis under New Topological:

Neutral-point potential balance is an important research problem of three level pwm converters.Switching device characteristics are inconsistent, control The factor such as algorithm processed and load all can cause midpoint potential uneven, leads to inverter output voltage wave distortion, switching device Bear voltage unbalanced it is also possible to the problems such as lead to three level to deteriorate to two level.And common-mode voltage is load neutral point to straight The mid-point voltage of stream bus, therefore midpoint potential are uneven to produce impact, the harm of aggravation common-mode voltage to common-mode voltage.

As shown in Fig. 1 (system topology figure) it is assumed that midpoint potential shifts δ u, the voltage of DC bus capacitor c1 For u_dcThe voltage of/2+ δ u, DC bus capacitor c2 is u_dc/2.Inverter exports the voltage of each phase alignment o at any one time It is changed into u_dc/ 2+ δ u, 0 or-u_dc/2.The common-mode voltage that after mid-point potential offset, three level non-isolated v2g systems produce is shown in Table 5.

The common-mode voltage that after table 5 mid-point potential offset, three level v2g systems produce

It can be seen that in three-phase tri-level v2g system, midpoint potential is uneven really to produce impact, limit to common-mode voltage Make common mode current inhibition.For coordinating above-mentioned control strategy, realize system common-mode voltage suppression simultaneously and midpoint potential is put down The Collaborative Control of weighing apparatus, the present invention proposes a kind of novel topological structure of non-isolation type three-phase tri-level v2g integrated system.Circuit is opened up Flutter structure as shown in Figure 10, introduce h bridge novel Circuit for Neutral-Point Voltage Balance at dc bus, because of likeness in form capitalization ' h ', therefore referred to as H bridge balancing circuitry.T in this topological structure_b1And t_b2For igbt switching tube, d_b1And d_b2For fly-wheel diode, l_b1And l_b2For balance Inductance, c₁And c₂For DC side derided capacitors.H bridge balancing circuitry is by igbt switching tube t_b1Inverse parallel fast recovery diode (or tool There is the switching tube t of endobiosis diode_b1) and one-way conduction fly-wheel diode d_b1Series connection, constitutes side brachium pontis, connects in the middle of it Connect balance inductance l_b1, the other end access DC side midpoint of balance inductance, both sides brachium pontis, common cathode, common-anode connect, i.e. upper end All it is connected to direct current positive bus, lower end is all connected to direct current negative busbar.

System modulation strategy adopts above-mentioned five-part form de-redundancy svm algorithm, on this basis, when circuit reaches stable state, DC bus-bar voltage v_dcConstant, the mode of operation of balancing circuitry according to the offset direction of midpoint potential, can be selected.By adjustment Electric capacity c₁And c₂The quantity of electric charge being carried, thus control the skew of midpoint potential.

DC side gathers derided capacitors c₁And c₂Output voltage signal u_dc1And u_dc2, as u in circuit_dc1<u_dc2When, midpoint Current potential is higher, controls h bridge balancing circuitry to be operated in buck chopper pattern.Therefore, switching tube t_b1Work, t_b2Disconnect, switching tube t_b1 Conducting, electric current from dc bus out, flows successively through derided capacitors c₁, balance inductance l_b1, switching tube t_b1, through system front stage circuits Dc/dc part anti-paralleled diode returns to DC side, makes inductance l_b1Energy storage, current loop by Figure 10 without arrow dotted line mark Go out；As switching tube t_b1When shutoff, electric current is through balance inductance l_b1, diode d_b1With derided capacitors c₁Form loop, storage In inductance l_b1On electric energy be recycled to dc bus, make midpoint potential reduce, until and c₂The voltage at two ends is in certain scope Inside reach balance, current loop is as shown in band arrow dotted line in Figure 10.

Conversely, as u in circuit_dc1>u_dc2When, midpoint potential is low, controls h bridge balancing circuitry to be operated in boost chopper mould Formula.Therefore, switching tube t_b2Work, t_b1Disconnect, the device of work is made up of with outer portion h bridge dotted line, switching tube t_b2Conducting, electricity Stream flows out from dc bus, flows successively through switching tube t_b2, balance inductance l_b2, derided capacitors c₂, through system front stage circuits dc/dc portion Anti-paralleled diode is divided to return to DC side, to electric capacity c₂Charge, and make inductance l_b2Energy storage, as switching tube t_b2When shutoff, Electric current is through balance inductance l_b2, derided capacitors c₂With diode d_b2Form loop, be stored in inductance l_b2On electric energy transfer to c₂ On, so that midpoint potential is raised, until and c₁The voltage at two ends reaches balance in certain scope.

The design of balance inductance

It is located in a controlling cycle of balancing circuitry, electric charge q is flowed out at midpoint_pqBy the average afterflow electricity flowing through balance inductance Stream i_pqDetermine, the switch periods of switching tube are t, and the wherein turn-on and turn-off time is respectively t_onAnd t_off, then have:

$q_{pq}={\&integral;}_0^t{i}_{pq}dt=i_{pq}\&centerdot;t---\left(4\right)$

Dc-link capacitance is c_l=c₁+c₂, the electric charge now flowing into midpoint is:

$q_{pq0}=\frac{c_l\&centerdot;(u_{c1}-u_{c2})}{2}---\left(5\right)$

Control neutral-point potential balance, make the electric charge at inflow and outflow midpoint in each cycle equal.I.e. | q_pq|=| q_pq0|, can Obtain i_pqExpression formula be:

$i_{pq}=\frac{c_l\&centerdot;(u_{c1}-u_{c2})}{2\&centerdot;t}---\left(6\right)$

Assume that switching tube works in an ideal case, do not consider tube voltage drop.When being operated in the buck chopper mould shown in Figure 10 During formula, switching tube t_b1Conducting, inductance l_b1Both end voltage can be expressed as:

$u_{l_{b1}}=u_{c2}=l_{b1}{\mathrm{\&delta;i}}_{l_{b1}\max }/t_{on}---\left(7\right)$

In formula (7),It is as switching tube t_b1Inductance l is flow through during conducting_b1Maximum current.

In the same manner, work as t_b1During shutoff, electric capacity c₁The voltage at two ends can be expressed as:

$u_{c1}=l_{b1}{\mathrm{\&delta;i}}_{l_{b1}\max }^{\&prime;}/t_{off}---\left(8\right)$

In formula (8),It is as switching tube t_b1Inductance l is flow through during shutoff_b1Maximum current.

Due to ideally, the electric current in inductance can not be mutated it can be assumed thatSetting h bridge balance The dutycycle of circuit is k, and from above formula, if k=50%, the charging and discharging of balance inductance is symmetric process.Assume electricity The linear change of inducing current, then flow through the maximum current of balance inductance when having switching tube conductingThus obtain The precise calculation of balance inductance is:

$\begin{array}{c}{l}_{b1}=u_{c2}\&centerdot;t_{on}\&centerdot;t/c_l\&centerdot;(u_{c1}-u_{c2})\\ =k\&centerdot;u_{c2}\&centerdot;t^2/c_l\&centerdot;(u_{c1}-u_{c2})\end{array}---\left(9\right)$

When balancing circuitry is operated in boost chopper pattern, still carry out according to the method described above deriving calculating.In order to simple For the sake of can be by inductance l_b1And l_b2It is designed to same parameter.Now, h bridge balancing circuitry can simplify and is equivalent to single brachium pontis band balance Induction structure, referred to as single bridge balancing circuitry, concrete topological structure such as Figure 12:

In single bridge arm balance circuit, as shown in figure 12, idiographic flow repeats no more work process corresponding with Figure 10.Single The topological structure with balance inductance for the brachium pontis only needs to the switching tube of a balance inductance and two inverse parallel fast recovery diodes, phase Ratio, in h bridge balancing circuitry, saves number of devices and hardware investment, but balance inductance has electric current stream in controlling cycle all the time Cross, that is, in running order all the time, design and selection to balance inductance are put forward higher requirement.

When particular hardware is realized, for avoiding balancing circuitry excessively frequently start and stop, can using stagnant chain rate compared with control strategy, Gather DC side derided capacitors c₁And c₂Output voltage signal u_dc1And u_dc2, and calculate the deviation of midpoint potential | u_c1-u_c2|, By setting a hysteresis of voltage δ u_setIf, the actual deviation of midpoint potential | u_c1-u_c2|>δu_setWhen, start balance Circuit, thus mid-point potential offset is controlled within the specific limits.

When v2g system works, in the present invention, the switching frequency of h bridge balancing circuitry is taken as 2.0khz, and dutycycle takes k= 50%, the switching frequency of h bridge balancing circuitry can be adjusted flexibly according to actual needs.Figure 13 is operated in blood pressure lowering for h bridge balancing circuitry Balance inductance l is flow through during chopping mode_b1Electric current, it can be seen that its work process is consistent with theory analysis.

As long as be described in detail it is clear that essentially without departing from the inventive point of the present invention and effect above to the present invention Really, will be readily apparent to persons skilled in the art deformation, is also all contained within protection scope of the present invention.

Claims (3)

1. a kind of non-isolation type three-phase tri-level v2g discharge and recharge topological structure is it is characterised in that described topological structure includes main electricity Road module and control circuit module, wherein:

Described main circuit module, is made up of three part cascades, is dc/dc part, h bridge balancing circuitry and dc/ac part respectively, car Carry electrokinetic cell through bi-directional half bridge changer, connect to direct current positive and negative busbar, between direct current positive and negative busbar, be provided with h bridge balancing circuitry With two derided capacitors c₁And c₂, it is in parallel with the outfan of bi-directional half bridge changer；Dc bus connects diode-clamped three Level pwm changer, three-phase alternating-current supply live wire accesses the upper and lower bridge arm junction of each phase brachium pontis through three-phase lc wave filter；Described H bridge balancing circuitry at dc bus, its h bridge balancing circuitry is by igbt switching tube t_b1Inverse parallel fast recovery diode, or there is body The switching tube t of endoparasitism diode_b1With one-way conduction fly-wheel diode d_b1Series connection, constitutes side brachium pontis, connects balance in the middle of it Inductance l_b1, the other end access DC side midpoint of balance inductance, both sides brachium pontis, common cathode, common-anode connect, and that is, upper end is all connected to Direct current positive bus, lower end is all connected to direct current negative busbar, by adjusting electric capacity c₁And c₂The quantity of electric charge being carried, thus control midpoint electricity The skew of position；

Described control circuit module, including sector judge module, basic vector selecting module, output order optimization module and Svpwm generation module.

2. according to claim 1 non-isolation type three-phase tri-level v2g discharge and recharge topological structure it is characterised in that described h bridge The operation mode 1 of balancing circuitry: DC side collection derided capacitors c₁And c₂Output voltage signal u_dc1And u_dc2, as u in circuit_dc1 <u_dc2When, midpoint potential is higher, controls h bridge balancing circuitry to be operated in buck chopper mode, switching tube t_b1Work, t_b2Disconnect, open Close pipe t_b1Conducting, electric current from dc bus out, flows successively through derided capacitors c₁, balance inductance l_b1, switching tube t_b1, through system Front stage circuits dc/dc part anti-paralleled diode returns to DC side, makes inductance l_b1Energy storage, as switching tube t_b1During shutoff, electric current warp Overbalance inductance l_b1, diode d_b1With derided capacitors c₁Form loop, be stored in inductance l_b1On electric energy to be recycled to direct current female Line, makes midpoint potential reduce, until and c₂The voltage at two ends reaches balance in certain scope；Described h bridge balancing circuitry Operation mode 2: as u in circuit_dc1>u_dc2When, midpoint potential is low, controls h bridge balancing circuitry to be operated in boost chopper mode, opens Close pipe t_b2Work, t_b1Disconnect, switching tube t_b2Conducting, electric current flows out from dc bus, flows successively through switching tube t_b2, balance inductance l_b2, derided capacitors c₂, return to DC side through system front stage circuits dc/dc part anti-paralleled diode, to electric capacity c₂Charge, and Make inductance l_b2Energy storage, as switching tube t_b2When shutoff, electric current is through balance inductance l_b2, derided capacitors c₂With diode d_b2Shape Become loop, be stored in inductance l_b2On electric energy transfer to c₂On, so that midpoint potential is raised, until and c₁The voltage at two ends is certain In the range of reach balance.

3. non-isolation type three-phase tri-level v2g discharge and recharge topological structure described in claim 1 control method it is characterised in that: Voltage on line side current sample module extracts three phase network electromotive force signal e_a,e_b,e_cWith three-phase current on line side signal i_a,i_b,i_c, warp Voltage and current double closed-loop module, generates reference voltage vector, sends into control circuit module, specifically comprises the following steps that

(1) determine big sector and little sector residing for reference vector, when selecting basic vector, reject output common mode voltage magnitude relatively Big basic vector, selects distance reference vector in little sector that reference vector is located nearest and output common mode voltage magnitude≤u_dc/6 Three basic vector state synthesized reference vectors；

(2) determine the output order of three basic vector states, svm sends out ripple mode using five-part form, every time using positive small vector as Start vector, the output order of 5 little sector basic vectors is:

poo→pon→pnn→pon→poo；Every phase on off state is not in by the saltus step of p to n, in each switch periods, Have one mutually to switch to be failure to actuate, total switch switching times are 4 times；

Be ensure reference vector change sector when, at most have a phase switch motion, 6 little sectors still using positive small vector as rise Beginning vector, adopts asymmetric vector composite analysis simultaneously,

Pon → oon → pon → ppn → pon, total switch switching times are similarly 4 times；

(4) other sector vector output order are analogized in accordance with the law.