CN101882882A - Inverter device and control method thereof - Google Patents

Abstract

The invention discloses an inverter device, comprising a serial-parallel multilevel inverter of sine pulse width modulation (SPWM) single-phase full-bridge inverters (FBI), wherein the SPWM-FBI application connection modes comprise single application, serial application, parallel application and serial-parallel application. The invention has the beneficial effects that the multilevel inverter directly in serial connection and superposition with the SPWM-FBI with an independent power supply has simple control, good output waveform and easy modularization as all the FBI have the same output power, and can use an IGBT as a switching element. Due to the above advantages, the topology can be widely used.

Description

DC-to-AC converter and control method thereof

Technical field

The present invention relates to a kind of DC-to-AC converter and control method thereof, relate in particular to the basic functional principle and the control method of the series-parallel multi-electrical level inverter of a kind of sinusoidal pulse width modulation (SPWM) single-phase full bridge formula inverter (FBI).

Background technology

Traditional diode clamp multi-electrical level inverter and control system thereof or striding capacitance clamping multi-level inverter and control system thereof, usually because complex structure, install problem such as compatibility not too with other and not convenient on occurring operating and producing, for example: (1) is when the output-voltage levels number is identical, there is the problem of all pressing, and employed number of elements is many, the many unpredictable problems of easier appearance, and cannot serviceability preferably IGBT make switch;

(2) power output has nothing in common with each other, and is difficult for realizing modularization, also is not easy to realize soft switch, does not meet modern high brief informationalized trend aborning, and wasting space and resource;

(3) control circuit complexity be difficult for realizing on electricity and circuit design, and error rate is higher;

(4) to output voltage waveforms to improve effect also not fully up to expectations.

Therefore, just because of above-mentioned various reasons, traditional DC-to-AC converter and control method thereof have exposed too many drawback, and the invention of a kind of novel DC-to-AC converter that overcomes above-mentioned defective and control method thereof is imperative.

Summary of the invention

At problem related in the background technology, through regular meeting following consequence appears promptly in the design of conventional inverter device and control method thereof, (1) when the output-voltage levels number is identical, exist and all press problem, and employed number of elements is many, (2) power output has nothing in common with each other, be difficult for realizing modularization, also be not easy to realize soft switch, (3) control circuit complexity, and error rate is higher; (4) to output voltage waveforms to improve effect also not fully up to expectations.

For overcoming above-mentioned defective, the present invention has adopted a kind of new technical scheme, a kind of DC-to-AC converter, it comprises: the series-parallel multi-electrical level inverter of sinusoidal pulse width modulation (SPWM) single-phase full bridge formula inverter (FBI): the application connecting mode of described SPWM-FBI includes: application separately, series connection are used, the in parallel application and the connection in series-parallel application; Described SPWM-FBI can adopt IGBT to make switch; The independent application of described SPWM-FBI is equivalent to a three phase full bridge formula inverter in three-phase inverter circuitry, its output voltage u is the phase voltage of three-phase inverter; The series connection of a described N SPWM-FBI is used, and forms an A phase inverter in three-phase circuit, and it adopts the mode of direct overlapped in series to obtain to eliminate the many level outputs of SPWM of the harmonic wave below NF in the phase voltage ± 1 time; When using, the parallel connection application of a described N SPWM-FBI and connection in series-parallel must adopt interphase reactor.

A kind of control method of DC-to-AC converter, it adopts the series-parallel multi-electrical level inverter overlapped in series of N sinusoidal pulse width modulation (SPWM) single-phase full bridge formula inverter (FBI) and the converter circuit of phasor calculation V/f control mode to utilize the equation of basic mathematical equation (stable state or dynamic) the derivation speed of motor to perform calculations, and provides the electric current set-point component Id* and the exciting current set-point component Ip* of reaction motor torque; Inverter is input to motor stator winding, comprises three-phase current ia, ib, the ic of excitation current component and rotor current component, the detection by current transformer also utilizes formula (10) that it is carried out the coordinate transform of three-phase to two-phase; Stator current is resolved into actual torque component Id and excitation component Iq, compare, obtain deviate Δ Id, the Δ Iq of torque and exciting current with Id, Iq and set-point Id*, Iq*; This deviate is transformed into voltage given value Vd* proportional with it, Vq* through pi regulator, and Vd*, Vq* are carried out the coordinate transform of two-phase to three-phase by following transform, obtains set point uA*, uB*, the uC* of stator voltage; Use Va*, Vb*, Vc* as the sinusoidal modulation wave signal then,, remove the drive controlling inverter, realize the V/f of motor is coordinated control by just can generate the SPWM drive signal of multi-electrical level inverter to the comparison of carrier wave triangular wave; Described when inverter adopts parallel connection or series-multiple connection stack, can realize also that with same circuit the V/f of motor coordinates control.

The invention has the beneficial effects as follows: the multi-electrical level inverter with direct overlapped in series of SPWM half-bridge converter (SPWM-FBl) of independent DC power supply is controlled simple, good output waveform, because the power output of each FBI is identical, thereby is easy to modularization, available IGBT makes switching device.These advantages will make this topology obtain extensive use.

Embodiment

The present invention has introduced a kind of basic functional principle and control method of series-parallel multi-electrical level inverter of new employing sinusoidal pulse width modulation (SPWM) single-phase full bridge formula inverter (FBI).Described SPWM half-bridge converter (SPWM-FBI) is the multi-electrical level inverter of overlapped in series directly, is another multi-electrical level inverter that develops after diode clamp and the many electricity of striding capacitance clamp inverter.It is compared with preceding two kinds of multi-electrical level inverters, has the following advantages.

(1) when the output-voltage levels number is identical, employed element is minimum, and does not exist and all press problem, can make switch with IGBT;

(2) power output of each FBI is identical, realizes modularization easily, also realizes soft switch easily; (3) control circuit is simple; (4) effective to the improvement of output voltage waveforms.

The output voltage of described SPWM-FBl is represented as described below: modulating wave is for sinusoidal wave, and carrier wave is a triangular wave, can adopt synchronous modulation (F is constant) and asynchronous modulation (F is variable).There is not repeatability being used for asynchronous when modulation .SPWM umber of pulse and pattern that system each cycle of ripple comprised of withering, thereby can not be that benchmark is analyzed with the modulating wave angular frequency, and it is proper to be that benchmark is analyzed its sideband distribution situation with carrier wave triangular wave angular frequency, just adopts dual Fourier series analytic approach.Compare with sinusoidal modulation wave and carrier wave triangular wave.For the positive half cycle of sinusoidal modulation wave, in the part of sine wave, obtain the positive pulse of positive half cycle SPWM waveform greater than triangular wave, in the part of sine wave, obtain the zero level of positive half cycle SPWM waveform less than triangular wave; For the negative half period of sine wave, in the part of sine wave, obtain the negative pulse of negative half period SPWM waveform less than triangular wave, in the part of sine wave, obtain the zero level of negative half period SPWM waveform greater than triangular wave.

For easy analysis, the carrier wave triangular wave is represented with piecewise linear function the slope of its two linear functions is respectively

With

Initial value is respectively zero-sum Uc, and Uc is the amplitude of carrier wave triangular wave.The angular frequency of supposing triangular wave is ω c, and the first phase parallactic angle is α, and then the mathematical notation formula of carrier wave triangular wave is

$u_c=\left\{\begin{array}{c}-({\mathrm{\ω}}_{c}t+\mathrm{\α}-2\mathrm{\πk})\frac{U_c}{\mathrm{\π}}+U_c,2\mathrm{\πk}\≤{\mathrm{\ω}}_{c}t\≤2\mathrm{\πk}+\mathrm{\π}\\ ({\mathrm{\ω}}_{c}t+\mathrm{\α}-2\mathrm{\πk}-\mathrm{\π})\frac{U_c}{\mathrm{\π}},2\mathrm{\πk}+\mathrm{\π}\≤{\mathrm{\ω}}_{c}t\≤2\mathrm{\πk}+2\mathrm{\π}\end{array}\right.---\left(1\right)$

K=1 wherein, 2,3 ...

The first phase parallactic angle of sinusoidal modulation wave is zero, and then the expression formula of μ s is

u _s＝U _asinω _st (2)

Carrier wave ratio

Modulation degree

The sampled point of SPWM ripple is at u _sWith u _sThe intersection point place, promptly at u _s=u _NThe place.

At sampled point a:

Make ω _sT=Y; ω _cT=X, then

X＝2πk+π-α-πMsinY

At sampled point b, the same can in the hope of:

X＝2πk+π-α+πMsinY

As can be known: X=ω ct to 2 π (k+1)+α interval, obtains the positive pulse of up at 2 π k+ α between a, b point, so can obtain the function of time of the SPWM waveform of up is

$Y=\frac{{\mathrm{\ω}}_s}{{\mathrm{\ω}}_c}X$

Function of time formula u _P(X, Y) can represent with two Fourier seriess of holding:

In the formula

Formula (3) substitution following formula is got

Get by Bessel function

$\frac{1}{\mathrm{\π}}{\∫}_0^{\mathrm{\π}}{e}^{\mathrm{jmM\π}\sin Y}{e}^{\mathrm{jnY}}\mathrm{dY}=J_n\left(\mathrm{mM\π}\right)\frac{e^{\mathrm{jn\π}}-1}{2}$

$\frac{1}{\mathrm{\π}}{\∫}_0^{\mathrm{\π}}{e}^{-\mathrm{jmM\π}\sin Y}{e}^{\mathrm{jnY}}\mathrm{dY}=J_n\left(\mathrm{mM\π}\right)\frac{1-e^{\mathrm{jn\π}}}{2}$

So A _Mn+ jB _Mn

When n is zero or even number, 1-e ^Jmn=0, A _Mn+ jB _Mn=0, when n is odd number, 1-e ^{Jm π}=2, so

$A_{\mathrm{mn}}=-\frac{2E}{\mathrm{m\π}}{J}_n\left(\mathrm{mM\π}\right)\sin m(\mathrm{\π}-\mathrm{\α})$

$B_{\mathrm{mn}}=\frac{2E}{\mathrm{m\π}}{J}_n\left(\mathrm{mM\π}\right)\cos m(\mathrm{\π}-\mathrm{\α})$

When m=0, e ^{Jmn (π-α)}=1, then

$A_{\mathrm{on}}+j{B}_{\mathrm{on}}=\frac{1}{{2\mathrm{\π}}^2}{\∫}_{-\mathrm{\π}}^{\mathrm{\π}}{\∫}_{-\mathrm{\π}}^{\mathrm{\π}}{u}_p(X,Y)e^{\mathrm{jnY}}\mathrm{dXdY}$

Because u _P(X Y) sees it is odd function from waveform, thus A _On=0

$B_{\mathrm{on}}=\frac{1}{{\mathrm{\π}}^2}{\∫}_0^{\mathrm{\π}}{\∫}_{-\mathrm{\π}}^{\mathrm{\π}}{u}_p(X,Y)\sin \mathrm{nYdXdY}$

$=\frac{E}{{\mathrm{\π}}^2}{\∫}_0^{\mathrm{\π}}{\∫}_{2\mathrm{\πk}+\mathrm{\π}-\mathrm{\α}-\mathrm{\π}M\sin Y}^{2\mathrm{\πk}+\mathrm{\π}-\mathrm{\α}+\mathrm{\π}M\sin Y}\sin \mathrm{nYdXdY}$

When n=1, Bol=ME; When n ≠ 1, BolO, so the dual Fourier series expression of SPWM waveform of up, that is the output voltage of SPWM-FBI represents that formula is

Calculate the frequency spectrum of SPWM-FBI output voltage up by formula (5), will eliminate the harmonic wave below F ± 1 time in up, the amplitude of up increases along with the increase of M is linear.Up is three level voltage waveforms.

The application connecting mode of described SPWM-FBI is: the application connecting mode of SPWM-FBI has 4 kinds: the application of promptly using separately, connect, the in parallel application and the series-multiple connection application.

The independent application of SPWM-FBI is equivalent to a three phase full bridge formula inverter in three-phase inverter circuitry, its output voltage up is the phase voltage of three-phase inverter, i.e. ua=up.

The series connection of N SPWM-FBI is used, and the A phase inverter of forming in three-phase circuit adopts the mode of direct overlapped in series to obtain the many level outputs of SPWM, to eliminate the harmonic wave below NF ± 1 in the phase voltage time.Suppose that DC power supply voltage that each SPWM-FBl adopts is identical and all equal E, their carrier wave triangular wave amplitude is Uc, the first phase parallactic angle 2 π/N that lags behind successively.If the first phase parallactic angle of first triangular wave is α 1=0, then second, third ... the first phase parallactic angle of N triangular wave is followed successively by

Sine voltage with same A phase is controlled as modulating wave, can obtain output voltage up1～upn, and up1～upn should have identical fundamental voltage.

Can obtain the Fourier series of up1～upn according to the first phase parallactic angle of formula (5) and carrier wave triangular wave.

Because u _P1～u _PnHave identical fundamental voltage, then sinm (π-0)+

(N gets negative sign when m equals odd number, and N gets positive sign when m equals even number).

So, A phase output voltage u _AFor

As seen from formula (6), the overlapped in series of N SPWM-FBI can be eliminated the harmonic wave below NF ± 1 time, and makes output voltage amplitude increase N doubly.Work as N=5, switching frequency

The time, in the dual Fourier series equation of A phase output voltage, can eliminate the following harmonic wave in 5 * 120 ± 1=600 ± 1, and the amplitude of uA also increases to 5 times of original value.

The parallel connection of N SPWM-FBI is used, the A phase inverter of forming in three-phase circuit.Adopt the mode of stack in parallel to obtain the output of SPWM voltage with multiple levels, to eliminate the harmonic wave below NF ± 1 in the phase voltage time.Each SWPM-FBI adopts identical their carrier wave triangular wave first phase parallactic angle of the DC power supply voltage E. 2 π/N that lags behind successively.If the first phase parallactic angle of first triangular wave is α 1=0, then second, i ... the first phase parallactic angle of N triangular wave is followed successively by Positive trichord wave voltage with same A phase is controlled as modulating wave, can obtain output voltage up1～upn, and up1～upn should have identical fundamental voltage.Because the instantaneous value of up1`upn is inequality, so must adopt the interphase reactor parallel connection.

Can get according to the nodal method of analysis in the electrotechnics

$(\frac{1}{X_1}+\frac{1}{X_2}+...+\frac{1}{X_N})u_A=\frac{u_{p1}}{X_1}+\frac{u_{p2}}{X_2}+...+\frac{u_{\mathrm{pN}}}{X_N}$

$u_A=(\frac{u_{p1}}{X_1}+\frac{u_{p2}}{X_2}+...+\frac{u_{\mathrm{pN}}}{X_N})/(\frac{1}{X_1}+\frac{1}{X_2}+...+\frac{1}{X_N})$

Work as X ₁=X ₂=...=X _NThe time

$u_A=\frac{1}{X_1}(u_{p1}+u_{p2}+...+u_{\mathrm{pN}})/\left(N\frac{1}{X_1}\right)$

$=\frac{u_{p1}+u_{p2}+...+u_{\mathrm{pN}}}{N}---\left(7\right)$

Can get by formula (6)

This substitution formula as a result (7) can be got

By formula (8) as can be known, the parallel connection of N SPWM-FBI stack can be eliminated the harmonic wave below NF ± 1 time, but can not increase output voltage amplitude.Because the instantaneous value difference of up1～upn, must adopt interphase reactor during stack therefore in parallel, this is the difference with overlapped in series.

The series-multiple connection of N SPWM-FBI is used, the A phase inverter of forming in three-phase circuit.Adopt the mode of connection in series-parallel stack to obtain the output of SPWM voltage with multiple levels, to eliminate the harmonic wave below NF ± 1 in the phase voltage time.Each SWPM-FBT adopts identical DC power supply voltage E, their the carrier wave triangular wave first phase parallactic angle 2 π/N that lags behind successively.If the first phase parallactic angle of first triangular wave is α 1=0, then second, third ... the first phase parallactic angle of N triangular wave is followed successively by And with the sine voltage of same A phase as modulating wave, obtain output voltage up1～upn and will have identical first-harmonic.When A phase inverter is composed in parallel by K series arm, each series arm is during by N/K SPWM-FBI series connection, then the arrangement position of each SPWM-FBI in the A circuitry phase: putting in order of SPWM-FBI is 1 in first series arm, i+K,, N-(K-1)=N-K+1; Putting in order of SPWM-FBI is 2 in second series arm, 2+K ..., N-(K-2)=N-k+2 ..., putting in order of the series arm towel SPWM～FBI is K, K+K ..., N-(K-K)=N.The output voltage of supposing each series arm is followed successively by u1～uk and has identical fundamental voltage, but therefore their instantaneous value department mutually must adopt interphase reactor to carry out parallel connection and superpose.

Can get according to the nodal method of analysis in the electrotechnics

$(\frac{1}{X_1}+\frac{1}{X_2}+...+\frac{1}{X_k})u_A=\frac{u_{p1}}{X_1}+\frac{u_{p2}}{X_2}+...+\frac{u_{\mathrm{pk}}}{X_k}$

$u_A=(\frac{u_{p1}}{X_1}+\frac{u_{p2}}{X_2}+...+\frac{u_{\mathrm{pk}}}{X_k})/(\frac{1}{X_1}+\frac{1}{X_2}+...+\frac{1}{X_k})$

Work as X ₁=X ₂=...=X _kThe time

$u_A=\frac{1}{X_1}(u_{p1}+u_{p2}+...+u_{\mathrm{pk}})/\left(k\frac{1}{X_1}\right)=\frac{u_{p1}+u_{p2}+...+u_{\mathrm{pN}}}{k}$

According to formula (6), then

By formula (9) as can be known: the stack of the series-multiple connection of N SPWM-FBI, can eliminate the harmonic wave below NF ± 1 time, the amplitude of uA fundamental voltage is single SPWM-FBI output voltage up amplitude

Formula (6) when K=I up-to-date style (9) is used with series connection is identical; Formula (8) when K=N up-to-date style (9) is used with parallel connection is identical.When adopting the series-multiple connection stack to use, N should get the integral multiple of K.

Moreover the control mode when the various stacks of SPWM-FBI are used is as described below:

The principle control circuit of N SPWM-FBI series, parallel and series-multiple connection stack, it is made up of three parts: a part is to produce N hysteresis successively

The triangular wave carrier generator at phase angle; Another part is to produce the three phase sine wave producer frequently that can amplitude modulation withers: third part is to compare with sine wave signal and carrier wave triangular wave, produces the comparator of SPWM drive signal.This control mode can make inverter applications in frequency converter or inverter.When being used for frequency converter, can realize V/f regulation and control system, phasor control, direct torque control or the control of Speedless sensor phasor etc.

In concrete utilization, adopt the converter circuit of N SPWM-FBI overlapped in series and phasor calculation V/f control mode.Utilize the equation of basic mathematical equation (stable state or dynamic) the derivation speed of motor to perform calculations, provide the electric current set-point component Id* and the exciting current set-point component Ip* of reaction motor torque.Inverter is input to motor stator winding, comprises three-phase current ia, ib, the ic of excitation current component and rotor current component, the detection by current transformer also utilizes formula (10) that it is carried out the coordinate transform of three-phase to two-phase.

$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=$

$\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}\cos \mathrm{\ωt}& \cos (\mathrm{\ωt}-\frac{2\mathrm{\π}}{3})& \cos (\mathrm{\ωt}+\frac{2\mathrm{\π}}{3})\\ \sin \mathrm{\ωt}& \sin (\mathrm{\ωt}-\frac{2\mathrm{\π}}{3})& \sin (\mathrm{\ωt}+\frac{2\mathrm{\π}}{3})\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]---\left(10\right)$

Stator current is resolved into actual torque component Id and excitation component Iq, compare, obtain deviate Δ Id, the Δ Iq of torque and exciting current with Id, Iq and set-point Id*, Iq*.This deviate is transformed into voltage given value Vd* proportional with it, Vq* through pi regulator, and Vd*, Vq* are carried out the coordinate transform of two-phase to three-phase by following transform, obtains set point uA*, uB*, the uC* of stator voltage.Use Va*, Vb*, Vc* as the sinusoidal modulation wave signal then,, remove the drive controlling inverter, realize the V/f of motor is coordinated control by just can generate the SPWM drive signal of multi-electrical level inverter to the comparison of carrier wave triangular wave.

$\left[\begin{array}{c}{V_A}^{*}\\ {V_B}^{*}\\ {V_C}^{*}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}\cos \mathrm{\ωt}& \sin \mathrm{\ωt}\\ \cos (\mathrm{\ωt}-\frac{2\mathrm{\π}}{3})& \sin (\mathrm{\ωt}-\frac{2\mathrm{\π}}{3})\\ \cos (\mathrm{\ωt}+\frac{2\mathrm{\π}}{3})& \sin (\mathrm{\ωt}+\frac{2\mathrm{\π}}{3})\end{array}\right]\left[\begin{array}{c}{V_d}^{*}\\ {V_q}^{*}\end{array}\right]$

When inverter adopts parallel connection or series-multiple connection stack, can realize also that with same circuit the V/f of motor coordinates control.

In sum: the multi-electrical level inverter with direct overlapped in series of SPWM half-bridge converter (SPWM-FBl) of independent DC power supply is controlled simple, good output waveform, because the power output of each FBI is identical, thereby is easy to modularization, available IGBT makes switching device.These advantages will make this topology obtain extensive use.

The above only is preferred embodiment of the present invention, is not the present invention is done any pro forma restriction.Any those of ordinary skill in the art are not breaking away under the technical solution of the present invention scope situation, utilize the method content of above-mentioned announcement that technical solution of the present invention is made many possible changes and modification, all belong to the scope of claims protection.

Claims (7)

1. DC-to-AC converter, it comprises: the series-parallel multi-electrical level inverter of sinusoidal pulse width modulation (SPWM) single-phase full bridge formula inverter (FBI) is characterized in that: the application connecting mode of described SPWM-FBI includes: application separately, series connection are used, the in parallel application and the series-multiple connection application.

2. DC-to-AC converter as claimed in claim 1 is characterized in that: described SPWM-FBI can adopt IGBT to make switch.

3. DC-to-AC converter as claimed in claim 2 is characterized in that: the independent application of described SPWM-FBI, in three-phase inverter circuitry, be equivalent to a three phase full bridge formula inverter, and its output voltage u is the phase voltage of three-phase inverter.

4. DC-to-AC converter as claimed in claim 2, it is characterized in that: the series connection of a described N SPWM-FBI is used, form an A phase inverter in three-phase circuit, it adopts the mode of direct overlapped in series to obtain to eliminate the many level outputs of SPWM of the harmonic wave below NF in the phase voltage ± 1 time.

5. DC-to-AC converter as claimed in claim 2 is characterized in that: the parallel connection application of a described N SPWM-FBI and series-multiple connection must adopt interphase reactor when using

6. the control method of a DC-to-AC converter is characterized in that:

1) adopts the series-parallel multi-electrical level inverter overlapped in series of N sinusoidal pulse width modulation (SPWM) single-phase full bridge formula inverter (FBI) and the converter circuit of phasor calculation control mode to utilize the equation of basic mathematical equation (stable state or dynamic) the derivation speed of motor to perform calculations, provide the electric current set-point component and the exciting current set-point component of reaction motor torque.

2) inverter is input to motor stator winding, comprises the three-phase current of excitation current component and rotor current component, carry out the coordinate transform of three-phase to two-phase by the detection of current transformer and with it.

3) stator current is resolved into actual torque component and excitation component, use with set-point to compare, obtain the deviate of torque and exciting current.

4) this deviate is transformed into voltage given value proportional with it through adjuster, will carry out the coordinate transform of two-phase to three-phase by transform, obtains the set point of stator voltage.

5) then by just can generate the SPWM drive signal of multi-electrical level inverter to the comparison of carrier wave triangular wave, remove the drive controlling inverter, realize coordination control motor.

7. the control method of DC-to-AC converter as claimed in claim 6 is characterized in that: described when inverter adopts parallel connection or series-multiple connection stack, can realize also that with same circuit the coordination of motor is controlled.