CN105226987A - A kind of inverter control method - Google Patents

Abstract

The present invention discloses a kind of inverter control method, it is characterized in that, described inverter adopts insulated gate bipolar transistor as the switching device of main circuit, and described method comprises: compared with reference voltage by described inverter output voltage, obtains the first error signal; Described error signal is regulated through the first controller, as current inner loop reference value; Inductor current value is compared with described current inner loop reference value, obtains the second error signal; Described second error signal is regulated through second controller, obtains sine wave signal; Described sine wave signal is compared with triangle carrier signal, obtains SPWM ripple; Controlled the switch of described insulated gate bipolar transistor by described SPWM ripple, thus and inverter power take-off produce expection output voltage.The inverter controlled by inverter control method of the present invention can be applicable to the situation of multiple load, and can meet the voltage request in load, is widely used.

Description

A kind of inverter control method

Technical field

The present invention relates to power electronic equipment control technology field, particularly relate to a kind of net inverter control method.

Background technology

Along with improving constantly of the production-scale continuous expansion of the modernization of industry and people's living standard, electric energy imbalance between supply and demand becomes increasingly conspicuous, and saves energy has become current study hotspot, has social effect and the economic implications of particular importance.Energy crisis, for alleviation energy shortage and environmental crisis, ensures social sustainable development, safeguards that national energy security plays an important role.

And electric energy feedback is in recent years in order to the most effective method of saves energy.Therefore, people start the development more paying attention to energy feedback system.The power electronics interface carrying out energy conversion adopts inverter usually.The control performance of inverter directly determines power supply reliability and the robustness of grid-connected system.

Inverter is the transformer of a kind of DCtoAC, is a kind of process of voltage inversion with converter.Transducer the alternating voltage of electrical network is changed into stable 12V direct current to export, and inverter is the High Level AC Voltage 12V direct voltage that Adapter exports being changed into high frequency.Two parts equally all have employed pulse-width modulation (PWM) technology using often.Its core is all a PWM integrated manipulator.That Adapter is UC3842, and inverter then adopts TL5001 chip.Operating voltage range 3.6 ~ the 40V of TL5001, its inside is provided with an error amplifier, adjuster, oscillator, the PWM generator having dead zone function, low-voltage variation loop and a short-circuit protection circuit etc.

The input interface section of inverter has 3 signals, 12V direct current input VIN, work enable voltage ENB and Panel current controling signal DIM.VIN is provided by Adapter, and ENB voltage is provided by the MCU on mainboard, and its value is 0 or 3V, and as ENB=0, inverter does not work, and during ENB=3V, inverter is in normal operating conditions; And DIM voltage is provided by mainboard, different DIM values, between 0 ~ 5V, is fed back to PWM controller feedback end by its excursion, and the electric current that inverter provides to load is also by difference, and DIM value is less, and the electric current that inverter exports is larger.

Contravarianter voltage starting-up later time is generally: when ENB is high level, exports high pressure and removes the backlight fluorescent tube lighting Panel.

Inverter PWM controller is made up of following function: internal reference voltage, error amplifier, oscillator and PWM, overvoltage protection, under-voltage protection, short-circuit protection, output transistor.

Inverter DC converting forms voltage conversion circuit by MOS switching tube and energy storage inductor, the pulse of input is amplified rear drive metal-oxide-semiconductor through push-pull amplifier and is done switch motion, make direct voltage carry out discharge and recharge to inductance, the other end of such inductance just can obtain alternating voltage.

Inverter LC vibrates and output loop: ensure that fluorescent tube starts the 1600V voltage needed, and after fluorescent tube starts, voltage is down to 800V.

Inverter output voltage feeds back: when loaded work piece, feedback sample voltage, plays the effect that stable I contravarianter voltage exports.

Inverter, by control mode classification, can be divided into the control of voltage source voltage control, voltage source Current Control, current source voltage and current source current to control four kinds of methods.Current source inverter refers at its DC side series connection one large inductance, inputs to provide galvanic current stream.But owing to adopting the system dynamic response of large inductance poor, most combining inverter all adopts voltage source inverter.

From the control mode of voltage, electric current, contravarianter voltage controls to be equivalent to inverter is equivalent to a voltage source, controls the phase place of its output voltage, frequency, amplitude reach system requirements.Current Control inverter inverter is equivalent to a current source, its electric current exported carried out to the control of amplitude, frequency, phase place.

At present, voltage control mode is mainly used in the inverter of independent operating, to meet the needs of load end.Especially a lot of voltage of load to superimposed has higher requirement, and therefore the voltage that adopts carries out closed-loop control as controlled quentity controlled variable more in this case.

And current control mode is mainly used in combining inverter, directly controls its output current and reach grid-connected requirement.The combining inverter control mode application of direct control grid-connected current tracing preset electric current is more extensive.Its control strategy is simply easy to design, as long as convert different controller, just can carry out cutting-in control in different ways.Concrete mode only needs the output current of control inverter to follow the tracks of line voltage, sets the size of output current simultaneously, can reach the object be incorporated into the power networks.Because its control method is relatively simple, effect is also relatively good, therefore uses extensively.

Summary of the invention

The present invention based on above one or more problem, provides a kind of inverter control method just, in order to solve voltage waveform in the single-phase inverter load that exists in prior art because of load changing, changes large problem.

Wherein, described inverter adopts insulated gate bipolar transistor as the switching device of main circuit, and described inverter control method comprises:

Described inverter output voltage is compared with reference voltage, obtains the first error signal;

Described error signal is regulated through the first controller, as current inner loop reference value;

Inductor current value is compared with described current inner loop reference value, obtains the second error signal;

Described second error signal is regulated through second controller, obtains sine wave signal;

Described sine wave signal is compared with triangle carrier signal, obtains SPWM ripple;

Controlled the switch of described insulated gate bipolar transistor by described SPWM ripple, thus and inverter power take-off produce expection output voltage.

Further, described first error signal is the difference of described inverter output voltage and reference voltage.

Further, described second error signal is the difference of inductor current value and described current inner loop reference value.

Further, described first controller is PI controller.

Further, described second controller is PI controller.

Preferably, described inductor current value is:

$i_L\left(s\right)=\frac{K_{PWM}(K_P+\frac{K_i}{s})}{(T_{S}s+1)(Ls+r)+K_{PWM}(K_P+\frac{K_i}{s})}{i}_{ref}\left(s\right)-\frac{1}{(T_{S}s+1)(Ls+r)+K_{PWM}(K_P+\frac{K_i}{s})}{u}_0\left(s\right);$

Wherein, K _pWMfor inverter multiplication factor, T _sfor the cycle of insulated gate bipolar transistor, r is inverter load, L _sfor filter inductance, K _pfor PI controller scale parameter, K _ifor PI controller integral parameter.

A kind of inverter control method provided by the invention, when load changing, the voltage waveform in the single-phase inverter resistive load of independent operating keeps stable, and the waveform of load current disturbance does not occur, and whole system has good anti-interference.The inverter that the method controls can be applicable to the situation of multiple load, and can meet the voltage request in load.Be widely used.

Accompanying drawing explanation

Fig. 1 is the flow chart of a kind of inverter control method of the embodiment of the present invention one;

Fig. 2 is the inverter system control block diagram of the embodiment of the present invention two;

Fig. 3 is the controller chassis of the current inner loop of the embodiment of the present invention two.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in detail.It should be noted that, if do not conflicted, each feature in the embodiment of the present invention and embodiment can be combined with each other, all within protection scope of the present invention.

Embodiment one

The embodiment of the present invention one provides a kind of inverter control method, and wherein, described inverter adopts insulated gate bipolar transistor as the switching device of main circuit, and PWM wave modulation mode is SPWM ripple.As shown in Figure 1, the method comprises:

101, described inverter output voltage is compared with reference voltage, obtain the first error signal;

Wherein, described first error signal is the difference of described inverter output voltage and reference voltage.Described first controller is PI controller.

102, described error signal is regulated through the first controller, as current inner loop reference value;

Wherein, described second error signal is the difference of inductor current value and described current inner loop reference value.Described second controller is PI controller.

103, inductor current value is compared with described current inner loop reference value, obtain the second error signal;

In the present embodiment, described inductor current value is:

$i_L\left(s\right)=\frac{K_{PWM}(K_P+\frac{K_i}{s})}{(T_{S}s+1)(Ls+r)+K_{PWM}(K_P+\frac{K_i}{s})}{i}_{ref}\left(s\right)-\frac{1}{(T_{S}s+1)(Ls+r)+K_{PWM}(K_P+\frac{K_i}{s})}{u}_0\left(s\right);$

Wherein, K _pWMfor inverter multiplication factor, T _sfor the cycle of insulated gate bipolar transistor, r is inverter load, L _sfor filter inductance, K _pfor PI controller scale parameter, K _ifor PI controller integral parameter.

104, described second error signal is regulated through second controller, obtain sine wave signal;

105, described sine wave signal is compared with triangle carrier signal, obtain SPWM ripple;

106, controlled the switch of described insulated gate bipolar transistor by described SPWM ripple, thus and inverter power take-off produce expection output voltage.

A kind of inverter control method provided by the invention, when load changing, the voltage waveform in the single-phase inverter resistive load of independent operating keeps stable, and the waveform of load current disturbance does not occur, and whole system has good anti-interference.The inverter that the method controls can be applicable to the situation of multiple load, and can meet the voltage request in load.Be widely used.

Embodiment two

Set up the control mode of inverter, first need the Mathematical Modeling determining inverter.If voltage is u in load _o, flowing through electric current is i _o, inverter output voltage is u _ab.Suppose that DC bus-bar voltage is steady, its value is constant, and switch is perfect switch, adopts State-space Averaging Principle to set up continuous print state averaging model.The condition of State-space Averaging Principle is adopted to be in discrete state when switch, when output fundamental frequency is far smaller than switching frequency, in a switch periods, adopt the mean value of state variable to replace its instantaneous value, obtain continuous print space State Average Model.

In inverter system, the value of r is usually very little, almost can ignore.Can find out, the inverter adopting LC filter is a type-Ⅱ system.When system institute bringing onto load is not purely resistive load, load-side can be equivalent to a current source.

At present, digital control is used to be applied more and more widely the mode that inverter controls.Because the switching frequency of system is very high, the sampling period is enough little, then can apply continuous space state model and directly design digitial controller.

But some control modes still need to adopt the separate manufacturing firms Mathematical Modeling of inverter to carry out digital design, as track with zero error, Repetitive controller etc. in the design process.Therefore use zero-order holder (ZOH-zeroorderhold) in systems in which, that is: using variable at the instantaneous value of sampling instant as its sampled value within this sampling period.Take " adding zero-order holder discretization " method, separate manufacturing firms model can be derived by inverter continuous model.

By in the process of continuous model discretization, the coefficient of state space equation is constant.Use x (n) respectively in the data of n-th sampling instant, y (n), u (n) represent, and the value in next sampling period adopts x (n+1) to represent.According to by the continuous state space equation of load equivalent in disturbance, the solution of this differential equation is:

$x\left(t\right)=e^{A(t-t_0)}x\left(t_0\right)+{\∫}_0^t{e}^{A(t-\mathrm{\τ})}Bu\left(\mathrm{\τ}\right)d\mathrm{\τ}.$

In addition, during inverter independent operating, following standard to be reached: the voltage in load is comparatively ideal sine wave, total harmonic distortion factor THD<3%, and can keep stable when load generation disturbance.Due to the high order harmonic component that the harmonic wave of single-phase independent operating inverter is mainly produced by switch on and off, therefore often adopt LC low pass filter in order to eliminate the high order harmonic component near switching frequency.The LC filter be made up of inductance capacitance has higher attenuation characteristic and lower output impedance, is generally used in independent operating inverter.

The cut-off frequency of LC filter be usually chosen as switching frequency 1/10 to 1/5 between, be far smaller than switching frequency, therefore filter can produce obvious attenuation to the high order harmonic component that on-off action produces.The relative LCL filter of computational methods of LC low pass filter is more simple, and effect is better than L filter.

First, filter inductance L is designed.The value of L has important effect to inverter system, and its reason is that inductance value is not only obvious on the static and dynamic performance impact of electric current loop, and can produce considerable influence to performances such as the power output of inverter, power factors.Specifically acting as of filter inductance: the effectively Resonance Wave Composition of filtering inverter output current; Inverter outlet side can be made to present the characteristic etc. of controlled current source; Realize the isolation of electrical network electromotive force and inverter output voltage, after making inverter output voltage after filtering, be substantially equal to line voltage.

The size of filter inductance is determined by inductive current ripple, generally gets the rated current of 15%-20%.If the inverter capacity of the present invention's research is 5kW, output rated voltage is 220V, then the size of rated current is: I=5000/220=22.7A.If inductive current ripple is 20% of load current value, then:

ΔI _max＝22.7×20％＝4.54A。

When supposing that current harmonics is maximum and grid-connected current peak value, PWM T period of wave that this peak point place is corresponding can be supposed, and when T is minimum, within this PWM cycle, line voltage is approximately constant and peak value u _net, T _sfor switch periods, T ₀for within this PWM period of wave, inverter output voltage equals the time of DC voltage.

SPWM ripple producing method of the present invention adopts unipolarity mode.Be far longer than the condition of fundamental frequency at switching frequency under, if duty ratio is D (t)=u _ab(t)/V _dc, then:

As t ∈ (0, T ₀) time, inverter output voltage u _ab=V _dc, now inductance L storage power, can obtain the electric current on L: ${\mathrm{\&Delta;i}}_1=\frac{V_{dc}-u_{net}}{L}\&CenterDot;T_0;$

As t ∈ (T ₀, T) time, inverter output voltage u _ab=0, now inductance L releases energy, and can obtain the electric current on L: ${\mathrm{\&Delta;i}}_2=\frac{-u_{net}}{L}\&CenterDot;(T-T_0).$

Due to when combining inverter works, continuous current mode without saturated, therefore Δ i ₁=-Δ i ₂, can obtain: $T_0=\frac{u_{net}}{V_{dc}}\&CenterDot;T_s,$

${\mathrm{\&Delta;i}}_1=\frac{V_{dc}-u_{net}}{L}\&CenterDot;T_0=\frac{V_{dc}-u_{net}}{L}\&CenterDot;\frac{u_{net}}{V_{dc}}\&CenterDot;T_s.$

Filter capacitor is designed.The cut-off frequency of LC filter is generally between 1/5 to 1/10 switching frequency, is assumed to be 1/10, that is: C=15 μ F.

Except adopting filter cutoff frequency to design, also can calculate according to electric capacity reactive power.Select to be need compromise at the numerical value of inductance and electric capacity.Electric capacity is larger, flows into the reactive current of electric capacity larger, then the electric current in inductance L and switching tube electric current also larger, thus the efficiency of reduction inverter system.Electric capacity is less, then consider that filtering performance inductance needs to increase, the pressure drop on inductance is increased.Large inductance also can cause higher cost simultaneously.Therefore, can calculate the size of electric capacity according to reactive power, generally get rated power 15% designs.In the design process, make inductance and capacitance all be in relatively reasonably interval, ensure filter effect and system effectiveness simultaneously.Still adopt inverter capacity to be 5kW, output rated voltage effective value is 220V, and fundamental frequency is that the parameter of 50Hz calculates: C=50 μ F.

According to above result of calculation, LC filter value is: L=3mH, C=20 μ F.

Amplitude-frequency characteristic, phase-frequency characteristic is worth according to above-mentioned L, C.By drawing the analysis of amplitude-frequency characteristic, phase-frequency characteristic, filter is 0 to low frequency signal gain, is-40dB to high-frequency signal gain, and decay is comparatively large, illustrates that the decay of filter to high order harmonic component is larger.Because LC filter directly accesses load, Bode diagram when system power is 5kW can be obtained.

Be more than the design principle of the present embodiment two inverter control method, the embodiment of the present invention two provides a kind of control method of inverter, and inverter wherein meets following condition:

1) select insulated gate bipolar transistor as the switching device of main circuit.Insulated gate bipolar transistor has multiple advantage, and as controlled simply, operating rate is fast, input impedance is large, drive circuit is simple, operating frequency is high, element volume is large.It is relatively long for reverse recovery time that it can overcome MOSFET, and when being applied in inverter, due to the existence of outputting inductance, time of afterflow is long, the defect easily burnt out.In the present embodiment, when selecting insulated gate bipolar transistor, the main selection considering its voltage quota and electric current quota.

2) for inverter PWM wave modulation mode, SPWM ripple is selected.Conclusion according in sampled-data control theory: the equal and variform burst pulse of momentum be added in there is inertia link on time, its effect is substantially identical, creates SPWM wave modulation method.The present invention is single phase model of building in MATLAB, all adopts SPWM ripple to control.Because Unipolar SPWM modulation system is compared with bipolar SPWM modulation system, there is lot of advantages: the frequency multiplication effect of switching frequency, DC voltage pulsation be little, reduce harmonic number etc., and the present invention adopts Unipolar SPWM modulation system.

When analytical system, need the drive circuit of inverter bridge and switching device to be used as a link.The input variable of this link is control voltage u, i.e. driving switch device, controls its break-make.The output variable of this link and inverter bridge output voltage u _ab.Generally will from u to u _abamplification coefficient regard constant as, be set to K _pWM, be called inverter multiplication factor.Its value K _pWM=V _dC/ V _tri, i.e. DC bus-bar voltage and triangular wave peak value ratio.In addition, there is hysteresis in inverter bridge modulation strategy, can be equivalent to the amplifying element K of a purely retarded _pWM/ T _ss+1, T _sfor switch periods.

For the inverter of independent operating, due to its voltage will be controlled, so adopt Voltage Feedback to control to improve systematic function.And current feedback has rapidity and accuracy, add to voltage close loop rapidity and the followability that current inner loop can improve system, improve very large to the performance of system.Therefore the present invention adopts load voltage outer shroud, the inverter control system of the control strategy design independent operating of inductive current inner ring.Controller adopts PI controller.Systematical control block diagram as shown in Figure 2.

Contrast Fig. 2, the inverter control method that the present embodiment provides, comprising:

1) outer shroud adopts instantaneous voltage value to control.Error signal after being compared with reference voltage level by output voltage regulates, as current inner loop reference value through PI controller.

2) inner ring adopts inductive current as variable.Inductive current instantaneous value and reference current are compared, the error of generation regulates through pi regulator, and the sine wave signal of generation compares with triangular wave carrier signal, produces SPWM ripple and controls IGBT.

In the present embodiment, filter parameter L=3mH, C=20 μ F.The control block diagram of current inner loop as shown in Figure 3.

The open-loop transfer function of system is:

Inductor current value is:

$i_L\left(s\right)=\frac{K_{PWM}(K_P+\frac{K_i}{s})}{(T_{S}s+1)(Ls+r)+K_{PWM}(K_P+\frac{K_i}{s})}{i}_{ref}\left(s\right)-\frac{1}{(T_{S}s+1)(Ls+r)+K_{PWM}(K_P+\frac{K_i}{s})}{u}_0\left(s\right);$

Wherein, K _pWMfor inverter multiplication factor, T _sfor the cycle of insulated gate bipolar transistor, r is inverter load, L _sfor filter inductance, K _pfor PI controller scale parameter, K _ifor PI controller integral parameter.

In control procedure, inductance inner ring needs to obtain good trace performance and dynamic response.When not considering voltage disturbance, system adopts PI controller can reduce steady-state error, according to typical PI controling parameters P while the increase stability of a system _kand i _k(design with the situation of 50 Ω ohmic loads, do not consider electric capacity).

When carrying out the design of inner ring PI controling parameters, because T is very little, can be close to and ignore.Only considering to design in the inner ring situation from inductance to load.

First the system open loop transfer function not adding controller is:

System corner frequency is: ω _c=L/r.

By the reset of PI controller at system corner frequency place, then have: K _i/ K _p=ω _c

In addition, inductive current inner ring needs the frequency characteristic reached to be: decline, through ω with-20dB/sec in low-frequency range _cafter decline with-40dB/sec.The decay to high band can be reached like this.Setting adds the cross-over frequency ω of the system open loop transfer function Bode diagram of PI controller _o, show that current inner loop is with or without the open-loop transfer function Bode diagram of PI link and closed loop step response diagram, can find out that the system adding PI link strengthens high band decay, steady margin is better.Namely the response that jumps reaches stable state at 0.018S, and system is dead-beat in the process reaching stable state, non-overshoot.Therefore, the system dynamic and static state performance adding PI controller is better.

Figure 3 shows that outer voltage control block diagram, during design outer shroud, because inductive current inner ring much larger than the tracking velocity of Voltage loop, will can be equivalent to 1 or an amplifying element by the tracking velocity of current inner loop.Outer voltage open-loop transfer function is:

Outer shroud needs good interference free performance, still adopts PI controller.Setting outer shroud corner frequency is 100Hz, and cross-over frequency is 10Hz.Solve: K _p1=7, K _i1=70.

Outer ring system is reaching the overlong time of steady-state response, and parameter is undesirable, needs to adjust.Suitable reduction K _p1, increase K _i1.In addition, in simulation process, also need to finely tune according to simulation result respectively two groups of PI parameters, in the hope of reaching better control effects.

In order to verify the control effects of the present embodiment inverter control method to independent operating inverter, in MATLAB/SIMULINK, single-phase inverter system is emulated.System adopts the filter parameter L=3mH calculated above, and C=20 μ F and dicyclo PI parameter, power to 50 Ω resistive loads.

Drawn by emulation experiment: when the given reference voltage of outer shroud is amplitude 310V ideal sine wave, voltage current waveform in resistive load and harmonic analysis can draw, voltage stabilization in resistive load is at about 310V, steady-state error is very little, total harmonic distortion factor THD<3%, meet the requirement that inverter powers to the load, i.e. voltage stabilization, and total harmonic distortion factor is less than 3%.Illustrate that the inverter control method of this present embodiment is applicable to the situation of independent operating inverter band resistive load.

In order to verify the performance of the inverter control method of the present embodiment under other loading condition of independent operating inverter band, respectively at t=0.02S, (from 50 Ω to 25 Ω) are suddenlyd change to resistive load in system, system band resistance sense load (R=50 Ω, L=50mH) and the situation of Rectified DC load emulate.

Can be drawn by emulation, adopt the independent operating single-phase inverter of the inverter control method control of the present embodiment when load changing, the voltage waveform change in resistive load is little, and amplitude still remains on about 310V, its waveform kept stable.In addition, not there is disturbance in the waveform of load current substantially, and illustrative system has good Immunity Performance, meets the simulation result under frequency domain.When system is to resistance sense load supplying, THD increases, but still remains within 3%.When system is powered to Rectified DC load, because the periodicity break-make of the non-linear of load and rectifier bridge makes electric current contain a large amount of harmonic wave, the harmonic wave pressure drop caused by inverter impedance makes inverter output voltage wave distortion, and THD increases to 3.56%.More than emulate explanation, the independent operating inverter that the inverter control method of the present embodiment controls can be applicable to multiple loading condition, and can meet the needs of voltage in load.

A kind of inverter control method provided by the invention, when load changing, the voltage waveform in the single-phase inverter resistive load of independent operating keeps stable, and the waveform of load current disturbance does not occur, and whole system has good anti-interference.The inverter that the method controls can be applicable to the situation of multiple load, and can meet the voltage request in load.Be widely used.

The foregoing is only embodiments of the present invention; not thereby the scope of the claims of the present invention is limited; every utilize specification of the present invention and accompanying drawing content to do equivalent structure or equivalent flow process conversion; or be directly or indirectly used in other relevant technical fields, be all in like manner included in scope of patent protection of the present invention.

Claims (6)

1. an inverter control method, is characterized in that, described inverter adopts insulated gate bipolar transistor as the switching device of main circuit, and described method comprises:

Described inverter output voltage is compared with reference voltage, obtains the first error signal;

Described error signal is regulated through the first controller, as current inner loop reference value;

Inductor current value is compared with described current inner loop reference value, obtains the second error signal;

Described second error signal is regulated through second controller, obtains sine wave signal;

Described sine wave signal is compared with triangle carrier signal, obtains SPWM ripple;

Controlled the switch of described insulated gate bipolar transistor by described SPWM ripple, thus and inverter power take-off produce expection output voltage.

2. inverter control method as claimed in claim 1, it is characterized in that, described first error signal is the difference of described inverter output voltage and reference voltage.

3. inverter control method as claimed in claim 1, it is characterized in that, described second error signal is the difference of inductor current value and described current inner loop reference value.

4. inverter control method as claimed in claim 1, it is characterized in that, described first controller is PI controller.

5. inverter control method as claimed in claim 1, it is characterized in that, described second controller is PI controller.

6. the inverter control method as described in claim 4 or 5, is characterized in that:

Described inductor current value is:

$i_L\left(s\right)=\frac{K_{PWM}(K_P+\frac{K_i}{s})}{(T_{S}s+1)(Ls+r)+K_{PWM}(K_P+\frac{K_i}{s})}{i}_{ref}\left(s\right)-\frac{1}{(T_{S}s+1)(Ls+r)+K_{PWM}(K_P+\frac{K_i}{s})}{u}_0\left(s\right);$

Wherein, K _pWMfor inverter multiplication factor, T _sfor the cycle of insulated gate bipolar transistor, r is inverter load, L _sfor filter inductance, K _pfor PI controller scale parameter, K _ifor PI controller integral parameter.