CN100576713C - Power-converting device - Google Patents

Abstract

The invention provides a kind of power inverter, comprising: PWM control part (9), it is to three-phase ac signal (Vum ^*, Vvm ^*, Vwm ^*) and the triangular wave carrier signal compare production burst width modulated ripple; Power converter main circuit portion (3), it drives switch element according to this pulse width modulation ripple, and direct voltage is converted to three-phase alternating voltage; And current detecting part (5,6), its direct current input side in this electric power converter main circuit portion detects dc bus current and reappears phase current; This power inverter also comprises voltage instruction changing unit (8), to change the cycle as voltage instruction during the odd number unit more than 3, during the described unit triangular wave carrier pitch of signal note increase or dull the minimizing during, and be zero with the mean value of the correction in the voltage instruction change cycle or be approximately zero corrected signal and be added on the three-phase ac signal.Thus, detect dc bus current accurately, suppress the high order harmonic component composition.

Description

Power-converting device

Technical field

The present invention relates to dc bus current is detected the power-converting device of the current information that obtains AC side.

Background technology

In power-converting devices such as inverter or transducer, realize the function of DC-AC conversion or AC-DC conversion by pulse width modulation (hereinafter referred to as " PWM ").Inverter is used in the drive system of alternating current motor (hereinafter referred to as " motor ") of syncmotor or induction motor etc., and in addition, transducer is widely used as the supply unit of inverter etc.

When utilizing inverter that motor is driven,, need only to extract accurately the first-harmonic composition that comprises in the alternating current for the generation torque of High Accuracy Control motor.Generally, be superimposed with the ripple component of the high frequency that is caused by PWM in alternating current, therefore, for example method by utilizing AC current sensor etc. is only extracted first-harmonic composition (with reference to patent documentation 1)

In recent years, proposed a kind ofly not utilize AC current sensor but the dc bus current of power-converting device is detected and extracts according to detected value the technology (with reference to patent documentation 2, patent documentation 3, patent documentation 4, patent documentation 5 and non-patent literature 1) of the information of alternating current.According to these technology, need not to use converter (current transformer) AC current sensor such as (CT) of having utilized Hall element, thereby the formation of device is simple, can save the space, reduces manufacturing cost.

Patent documentation 1: the spy opens flat 6-189578 communique

Patent documentation 2: the spy opens the 2002-119062 communique

Patent documentation 3: the spy opens the 2004-64903 communique

Patent documentation 4: the spy opens the 2001-327173 communique

Patent documentation 5: the spy opens flat 10-155278 communique

Non-patent literature 1: Fu Benzhe, cross limit good fortune favour, shore root foreigner, Lin Yangyi: " the wave distortion method of revising based on the alternating current computing in the 1 shunt resistance mode and fluctuation of improvementing " semi-conductor electricity force transformation industry electric power electric application Research on Contract meeting, SPC-05-99, pp.1-6 (2005)

The method of patent documentation 4 is: 1 cycle that will generate the triangular wave carrier signal of pwm signal is divided into first-half period and between latter half, detects dc bus current in during any in during these.Because the ac output voltage of power converter is low more, therefore difficult more this dc bus current of detection, adds correction voltage at first-half period to ac output voltage, increases output voltage values itself and detects dc bus current.In addition, between latter half, deduct the correction voltage that adds at first-half period, make can not exert an influence first-half period and the average output voltage between latter half.

But, under the situation of utilizing this technology for detection alternating current, produce torque pulsation, precision deterioration sometimes.By applying correction voltage, can produce original unwanted electric current and change, this current change quantity becomes " error " current detection value is exerted an influence, and the result can cause torque pulsation generation, torque precision deterioration.Especially, under the situation that inductance is little or carrier frequency is low of motor, be easy to generate, cause going wrong by revising the current error that voltage causes.

And, only during first-half period and between latter half any, detect dc bus current and the deviation of the current detection value that produces also is listed as problem.This problem is owing to different the causing of timing that detects between first-half period when carrying out the detection of dc bus current with time division way and latter half.That is, the value of the current fluctuation that produces by the switch transition of PWM two regularly different, therefore, if the detection electric current then can produce deviation in only during the either party.This is especially obvious under the big situation of current fluctuation, can increase the current error that described correction voltage causes, therefore becomes problem.

In addition, about the alternating current distortion compensation of present worth again, the method for patent documentation 1 is arranged.But this method needs compensation operation when each the detection, may cause computational load to increase.In non-patent literature 1, the simple and easy penalty method that reduces computational load is also disclosed simultaneously.This method only limits to use under the timing that detects is fixed as the situation of the timing consistent with the maximum of triangular wave carrier signal and minimum value, is difficult under the regularly different modes use detecting.

In addition, in the method for patent documentation 5, be defined as " during the subordinate " about integer/one, in this period, carry out the mensuration (detection) and the compensation of dc bus current cycle of carrier frequency.Also same in this mode with the technology of patent documentation 4, during subordinate in, carry out the detection of correction, correction and the dc bus current of output voltage.As a result, will be to the consistent frequency content of cycle during voltage instruction value stack and the subordinate, the generation frequency content lower in the alternating current than the frequency content of carrier signal.This low-frequency component becomes its integer/one with respect to carrier frequency, therefore, is in audible range probably.For example, the semiconductor device that is equipped with as the inverter lockset is extensive use of IGBT, is limited to about 20kHz on its carrier frequency.Therefore, if its integer/one then is below the 10kHz, to be in audible range.The one-tenth of audible range is divided into electromagnetic noise becomes ear-piercing noise, in addition, if the frequency content of alternating current is consistent with the resonance frequency of mechanical system, then produces excessive vibration, may make device generation undesirable condition.

Summary of the invention

Problem of the present invention is, provides a kind of energy high Precision Detection dc bus current also can suppress the power-converting device of high order harmonic component composition.

In order to solve described problem, power inverter of the present invention comprises: the PWM control part, and it compares three-phase ac signal and triangular wave carrier signal, production burst width modulated ripple; Power converter circuit portion, it drives switch element according to this pulse width modulation ripple, and direct voltage is converted to three-phase alternating voltage; And current detecting part, its direct current input side in this electric power converter circuit part detects dc bus current and reappears phase current; This power inverter also comprises the voltage instruction changing unit, to change the cycle as voltage instruction during the odd number unit more than 3, during the described unit described triangular wave carrier pitch of signal note increase or dull the minimizing during, and the mean value of the correction in the described voltage instruction change cycle be approximately zero corrected signal be added on the described three-phase ac signal.

By the triangular wave carrier pitch of signal note is increased or dull reduce during as during the unit, with during the odd number continuous during three these units as one-period, on voltage instruction value, add correction, enlarged the width of the pulse type electric current that flows in the dc bus current thus, realized that current with high accuracy detects.In addition, the frequency content that voltage instruction value is superposeed not is the integral multiple for the cycle of triangular wave carrier signal.Therefore, the high order harmonic component composition is suppressed, and can reduce the generation of electromagnetic noise.

(invention effect)

According to the present invention, can detect dc bus current accurately, suppress the high order harmonic component composition.

Description of drawings

Fig. 1 is the pie graph of first embodiment of the invention;

Fig. 2 is the key diagram about the variation of the voltage instruction value of first embodiment of the invention;

Fig. 3 is the voltage instruction value of first embodiment of the invention and the graph of a relation of dc bus current;

Fig. 4 is the key diagram about the generation of the dc bus current pulse with minimum pulse width of first embodiment of the invention;

Fig. 5 is the pie graph of second embodiment of the invention;

Fig. 6 is the pie graph of third embodiment of the invention;

Fig. 7 is the key diagram about the variation of the voltage instruction value of four embodiment of the invention.

Among the figure: the 1-DC power supply; The 2-smmothing capacitor; 3-power converter main circuit portion (power converter circuit portion); The 4-alternating current motor; The 5-shunt resistance; The 6-current detecting part; 7-voltage instruction value generating unit; 8-voltage instruction changing unit; The 9-PWM control part; 9a-triangular wave carrier signal generating unit; The 10-rotor-position is inferred operational part; The 11-speed controlling portion; The 12-rotor-position sensor; 100,110,120-power-converting device.

Embodiment

(first execution mode)

Utilize the pie graph of Fig. 1, first execution mode of the present invention is described.The power-converting device 100 of Fig. 1 comprises: DC power supply 1, the smmothing capacitor 2 that is connected in parallel, by shunt resistance 5 with the both end voltage of smmothing capacitor 2 be applied to input side power converter main circuit portion (power converter circuit portion) 3, the alternating current motor 4 that is connected with the interchange output of power converter 3, be installed on alternating current motor 4 also rotor-position sensor 12, the microcomputer 8 of output rotor angle signal θ.

Microcomputer 8 possesses following function: current detecting part 6, and the dc bus current IDC that flows in the input shunt resistance 5 reappears phase current Iuc, Ivc, Iwc; Voltage instruction value generating unit 7, phase current Iuc, the Ivc that input reappears, Iwc and the current instruction value Id*, the Iq* that apply from the outside arbitrarily export the first voltage instruction value Vu*, Vv*, Vw* according to rotor angle signal θ; Voltage instruction changing unit 8 with the first voltage instruction value Vu*, Vv*, Vw* and voltage instruction change value Δ Vuc, Δ Vvc, Δ Vwc addition, is exported the second voltage instruction value Vum*, Vvm*, Vwm*; PWM control part 9 by being that the triangular wave carrier signal that the second voltage instruction value Vum*, Vvm*, Vwm* and triangular wave carrier signal generating unit 9a generate compares to three-phase ac signal, generates the switch transition signal.

Electric power variation device main circuit portion 3 carries out switch transition based on the switch transition signal to semiconductor element, thus the output three-phase alternating voltage, and three-phase current Iu, Iv, Iw flow.In addition, by the switch transition signal is also offered current detecting part 6, determine the detection timing of dc bus current IDC thus.

At first, the voltage instruction changing unit 8 that the feature as present embodiment is constituted is described.

As during the unit, be defined as 1 cycle (with reference to Fig. 2 (a)) during after the odd number that these are continuous (n) adds up to during the voltage instruction change cycle increases the dullness of triangular wave carrier or during dull the minimizing.In the voltage instruction change cycle, exist during the half period of n carrier cycle, specific for these half periods are carried out, definition as the ordinal number k of " k half period during " (k=1,2,3 ..., n).Fig. 2 is the sequential chart under the n=3 situation.Fig. 2 (a) is the waveform of triangular wave carrier signal, Fig. 2 (b) changes the time of the ordinal number k of the order during the expression half period, Fig. 2 (c) is voltage instruction change value Δ Vuc, and Fig. 2 (d) is the first voltage instruction value Vu*, Vv*, Vw* and the second voltage instruction value Vum*, Vvm*, Vwm*.

The final voltage instruction that carries out the PWM modulation is the second voltage instruction value Vum*, Vvm*, Vwm*, this is represented then become following formula with mathematical expression.

[mathematical expression 1]

$\left[\begin{array}{c}\mathrm{Vum}*\left[k\right]=\mathrm{Vu}*\left[k\right]+\mathrm{\ΔVuc}\left[k\right]\\ \mathrm{Vum}*\left[k\right]=\mathrm{Vv}*\left[k\right]+\mathrm{\ΔVvc}\left[k\right]\\ \mathrm{Vwm}*\left[k\right]=\mathrm{Vw}*\left[k\right]+\mathrm{\ΔVwc}\left[k\right]\end{array}\right.,(k=\mathrm{1,2,3}...,n)...\left(1\right)$

In addition, according to formula (2), voltage instruction change value time average in 1 cycle in voltage instruction change cycle is zero or is approximately zero.

[mathematical expression 2]

$\left[\begin{array}{c}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\left(\mathrm{\ΔVuc}\right[k\left]\right)=0\\ \underset{i=1}{\overset{n}{\mathrm{\Σ}}}\left(\mathrm{\ΔVvc}\right[k\left]\right)=0\\ \underset{i=1}{\overset{n}{\mathrm{\Σ}}}\left(\mathrm{\ΔVwc}\right[k\left]\right)=0\end{array}\right.,(k=\mathrm{1,2,3},...,n)...\left(2\right)$

This is the first voltage instruction value Vu*, Vv*, the Vw* that is exported for fear of voltage instruction value generating unit 7 and produces difference between the voltage that alternating current motor 4 applies.

In addition, in Fig. 2 (d), be the example that only adds voltage instruction change value Δ Vuc on mutually at U, V is not carried out any correction mutually with W mutually, become Vvm*=Vv*, Vwm*=Vw*.

Below, the addition method of the voltage instruction change value that has feature in the present embodiment most is described.For the purpose of simplifying the description, only add voltage instruction change value Δ Vuc on mutually at U.

At first, in order to detect dc bus current IDC, need add correction amount Euc (the definite method about Δ Euc is described in the back) to the first voltage instruction value Vu*.

In the present embodiment, n is that the odd number this point is very important, for example establishes n=3.In this case,

[mathematical expression 3]

$\left[\begin{array}{c}\mathrm{\ΔVuc}\left[1\right]=-\frac{\mathrm{\ΔEuc}}{2}\\ \mathrm{\ΔVuc}\left[2\right]=\mathrm{\ΔEuc}\\ \mathrm{\ΔVuc}\left[3\right]=-\frac{\mathrm{\ΔEuc}}{2}\end{array}\right....\left(3\right)$

Then, voltage instruction value is changed.The detection of dc bus current IDC is carried out during ordinal number k=2, at this moment, adds needed correction voltage Δ Euc.With carrier wave half period of this ordinal number k=2 as " between the full voltage validation period ".In addition, with add the ordinal number k=1 of Δ Euc/2 and ordinal number k=3 during as " between the half voltage validation period ".In addition, when ordinal number k=2, need Δ Euc, but the adding up to of the correction voltage of ordinal number k=1 and ordinal number k=3-Δ Euc gets final product, do not require stringency.

In modes such as patent documentation 4, for example, after adding Δ Euc during the dullness increase of triangular wave, detect dc bus current IDC, during ensuing dull the minimizing, add-Δ Euc (amount that will add deducts), thus the generation of the error of inhibition and primary voltage instruction.In the present embodiment, add in order to detect dc bus current IDC that to revise the voltage this point at first sight identical with patent documentation 4, but be divided into half correction voltage after also will cutting apart and distinguish difference on the addition this point in the front and back between detection period will revising voltage.

According to same idea, when n=5, give voltage instruction change value according to the mode of mathematical expression 4 or mathematical expression 5.

[mathematical expression 4]

$\left[\begin{array}{c}\mathrm{\ΔVuc}\left[1\right]=-\frac{\mathrm{\ΔEuc}}{2}\\ \mathrm{\ΔVuc}\left[2\right]=\mathrm{\ΔEuc}\\ \mathrm{\ΔVuc}\left[3\right]=-\mathrm{\ΔEuc}\\ \mathrm{\ΔVuc}\left[4\right]=\mathrm{\ΔEuc}\\ \mathrm{\ΔVuc}\left[5\right]=-\frac{\mathrm{\ΔEuc}}{2}\end{array}\right....\left(4\right)$

[mathematical expression 5]

$\left[\begin{array}{c}\mathrm{\ΔVuc}\left[1\right]=\frac{\mathrm{\ΔEuc}}{2}\\ \mathrm{\ΔVuc}\left[2\right]=-\mathrm{\ΔEuc}\\ \mathrm{\ΔVuc}\left[3\right]=\mathrm{\ΔEuc}\\ \mathrm{\ΔVuc}\left[4\right]=-\mathrm{\ΔEuc}\\ \mathrm{\ΔVuc}\left[5\right]=-\frac{\mathrm{\ΔEuc}}{2}\end{array}\right....\left(5\right)$

In this case, in formula (4), can carry out current detecting, in formula (5), can carry out current detecting with ordinal number k=3 with ordinal number k=2 or ordinal number k=4.When all beginning with the voltage instruction change cycle (ordinal number k=1) and when finishing (ordinal number k=n) as " between the half voltage validation period ", in addition during conduct " between the full voltage validation period ".

Below, utilize Fig. 3, the effect of present embodiment is described.

According to the second voltage instruction value Vum*, Vvm*, the Vwm* that try to achieve by voltage instruction changing unit 8, undertaken based on triangular wave PWM control relatively by PWM control part 9.The result of PWM control has been carried out in expression in Fig. 3 (d), is illustrated in the current impulse that produces among the dc bus current IDC.

To the three-phase voltage command value that compares with the triangular wave carrier signal, according to the big order of value, phase, the minimum phase of voltage then become following situation in the middle of definition voltage maximal phase, the voltage in Fig. 3.

Voltage maximal phase → U phase

Phase in the middle of the voltage → V phase

The minimum phase of voltage → W phase

In addition, which in the three-phase (U phase, V phase, W phase) to be phase or the minimum phase of voltage in the middle of voltage maximal phase, the voltage about, change by per 60 degree according to exchanging phase place.

Produce the electric current and the minimum electric current mutually of voltage of voltage maximal phase among the known dc bus current IDC with time division way.During the dullness of triangular wave carrier signal increases (Fig. 3 (a)), the electric current I DC1 of the minimum phase of voltage at first appears, and the electric current I DC2 (Fig. 3 (d)) of voltage maximal phase then appears.(Fig. 3 (a)) in contrast, the electric current I DC1 of voltage maximal phase at first occurs during dullness reduces, and the electric current I DC2 of the minimum phase of voltage next occurs.

In the example of Fig. 3, establish n=3, U is added Δ Vuc mutually, W is added Δ Vwc mutually, change voltage instruction value.The result as can be known, during ordinal number k=2, the pulse duration of dc bus current IDC broadens.And then as can be known, the triangular wave carrier signal during ordinal number k=2 alternately switches (Fig. 3 (a) and (b)) between dullness increase and dull the minimizing.This is owing to voltage instruction is made as the half period of carrier wave " odd number (being n=3 in Fig. 3) " between conversion period.As a result, the triangular wave carrier signal the during detection of dc bus current IDC not unique (will " only detect monotone increasing added-time or monotone decreasing after a little while " be called unique) can have been obtained the current detecting of balance.As a result, the unfavorable condition disappearance as patent documentation 4 can increase substantially current detection accuracy.

In addition, the voltage instruction change cycle becomes 1.5 times of triangular wave carrier cycle when n=3, and the frequency content that as patent documentation 5 voltage instruction value is superposeed not is the integral multiple for the cycle of triangular wave carrier signal.That is, if to establish carrier frequency be 20kHz, then the high order harmonic component of adding by voltage instruction changing unit 8 becomes to be divided into 13.3kHz (=20kHz/1.5) composition.Though this value is in audible range, people's ear is difficult to hear, and is quiet effective.

And then if n=5, then high order harmonic component becomes to be divided into 8kHz (=20kHz/2.5) composition.This value is in audible range, and people's ear can be heard, therefore can sacrifice quiet effect.But near 13kHz, the frequency of the high order harmonic component composition that then can stagger can be avoided the unfavorable condition that is caused by the device vibration as if the mechanical resonance frequency of supposing device.

As mentioned above, on the high order harmonic component composition that adds by voltage instruction changing unit 8, superposeed voltage instruction has been changed the frequency content of cycle as 1 cycle.If establishing 1 cycle in this voltage instruction change cycle is Ta, 1 cycle of establishing the triangular wave carrier signal is Tc, represents then to become formula (6) with n.

[mathematical expression 6]

$\mathrm{Ta}=n\&CenterDot;\frac{\mathrm{<figure-callout\; id="2"\; label="Tc"\; filenames="C2007101864990018H1.png,C2007101864990019H1.png"\; state="\{\{state\}\}">Tc</figure-callout>}}{2}...\left(6\right)$

According to formula (6), be fa if establish the frequency content of stack, then become the inverse of Ta, represent by formula (7).

[mathematical expression 7]

$\mathrm{fa}=\frac{2}{n}\&CenterDot;\frac{1}{\mathrm{Tc}}=\frac{2}{n}\&CenterDot;\mathrm{fc}...\left(7\right)$

In addition, the correction amount Euc in formula (3)～formula (5) is as follows gets final product by asking for the same method of patent documentation 4.

The voltage maximum phase current that flows as dc bus current IDC and the current pulse width of the minimum phase current of voltage respectively by in the middle of the voltage mutually the difference of and instruction value determine.If this current pulse width is not guaranteed the size more than setting, then can't be detected electric current.

Here said " setting " is meant, during having considered to prevent idle time (dead time) that the branch, short-circuit of semiconductor element uses, produce the ring (ringing) that causes by switch transition (switching) during or the minimum widith of sampling retention time of A/D converter etc., determine also can by the restriction on the hardware.This minimum value that can detect the conducting width of electric current is defined as minimum pulse width Tpw.

As mentioned above, make that by revising the potential difference of two-phase of voltage instruction value must be more than the voltage suitable with minimum pulse width Tpw, thereby can detect the electric current of voltage maximal phase and the minimum phase of voltage.Therefore, as correction amount Euc, the Δ Evc of voltage instruction change value addition, the relation that Δ Ewc becomes following formula respectively.

[mathematical expression 8]

$\left\{\begin{array}{c}0\&le;\left|\mathrm{\&Delta;Euc}\right|\&le;V\left(\mathrm{Tpw}\right)\\ 0\&le;\left|\mathrm{\&Delta;Evc}\right|\&le;V\left(\mathrm{Tpw}\right)\\ 0\&le;\left|\mathrm{\&Delta;Evc}\right|\&le;V\left(\mathrm{Tpw}\right)\end{array}\right....\left(8\right)$

The size of the difference of each voltage instruction value then need not to add correction if more than the voltage V (Tpw) suitable with minimum pulse width Tpw.

In addition, according to the method for present embodiment, maximum can only obtain the biphase current value, under the situation of three-phase alternating-current motor, generally disconnect (open) neutral point voltage, therefore, according to kirchhoff (Kirchhoff) first law, can utilize the relational expression of formula 9 to obtain the current value that remains a phase.

[mathematical expression 9]

Iuc+Ivc+Iwc＝0···················(9)

In addition, voltage instruction value generating unit 7 is carried out the general action of use in the existing alternating current motor control.That is, in voltage instruction value generating unit 7,, export the first voltage instruction value Vu*, Vv*, Vw* according to the reproduction electric current I uc, Ivc, the Iwc that obtain by current detecting part 6 and current instruction value Id*, the Iq* that applies arbitrarily.The reproduction electric current I uc here, Ivc, Iwc are the of acs under the stator coordinate system, therefore, generally import rotating coordinate transformation (dq conversion), and electric current is handled as DC quantity, realize following the Current Control of current instruction value.Can carry out the dq inverse transformation by the output to current controller, the calculating of ac is the value on the first voltage instruction coordinate (rotational coordinates), obtains the first voltage instruction value Vu*, Vv*, Vw*.

In addition, in alternating current motor control, need phase information, when adopting synchronous motor, need the position transducer of rotor in order to carry out coordinate transform.In addition, as long as shunt resistance shown in Figure 15 can detect dc bus current IDC, also can replace shunt resistance 5 and by DC current sensor formations such as (DCCT).

Utilize Fig. 4, the waveform of the dc bus current IDC during to n=5 describes.Fig. 4 (a) is the waveform of triangular wave carrier signal, and Fig. 4 (b) changes the time of ordinal number k, and Fig. 4 (c) is the waveform of voltage instruction change value Δ Vuc, and Fig. 4 (d) is the waveform of dc bus current IDC.In dc bus current IDC, produce voltage maximal phase pulse and the voltage minimum phase pulse consistent respectively with the alternating current of voltage maximal phase and the minimum phase of voltage.In Fig. 4, add voltage instruction change value Δ Vuc based on formula (5).That is,, make the pulse duration of voltage maximal phase pulse consistent with minimum pulse width Tpw by adding correction amount Euc when the ordinal number k=3.According to Fig. 4 (d), reach one of the middle appearance of per 5 of the above voltage maximal phase pulse (symbol 1～5) of minimum pulse width Tpw (that is, n), become the frequency content of 1/n with respect to the pulse frequency of dc bus current IDC.In addition, have the number of the voltage maximal phase pulse of the pulse duration more than the minimum pulse width Tpw in 1 cycle in change cycle at voltage instruction, equate with the number that becomes Δ Vuc=Δ Euc, therefore, under the situation of formula (4) being 2, is 1 under the situation of formula (5).

In Fig. 4, according to differentiating pulse of voltage maximal phase and the minimum pulse mutually of voltage during the dullness increase of triangular wave carrier signal with during dull the minimizing.But, if the switch transition state of the semiconductor element of observation electric power converter main circuit portion 3 then can similarly be differentiated.

According to present embodiment, the dullness of triangular wave carrier signal increased or dull reduce during as during the unit, with during the odd number continuous during this unit more than three as one-period, on voltage instruction value, add correction.Thus, the pulse duration of dc bus current IDC is elongated, can carry out current with high accuracy and detect.That is,, also can improve current detection accuracy, therefore, can carry out correct position and infer, can realize unprecedented torque precision even only use the dc bus current transducer.In addition, be not integral multiple to the frequency content of voltage instruction value stack for the cycle of triangular wave carrier signal, therefore can reduce the generation of electromagnetic noise.And then, during the unit of the front and back during the unit that carries out addition, deduct voltage instruction value correction 1/2, thereby make correction equalization during whole.

(second execution mode)

Utilize the pie graph of Fig. 5, second execution mode of the present invention is described.In Fig. 5, the formation of the power-converting device 100 of 110 pairs first execution modes of power-converting device has been deleted rotor-position sensor 12, and replaces rotor-position sensor and the rotor-position that appended the rotor-position of inferring alternating current motor 4 is inferred operational part 10.

Rotor-position infers that operational part 10 will reappear the reproduction electric current I uc that obtains, Ivc, Iwc as input to motor current Iu, Iv, Iw, carry out the deduction computing of rotor-position, the phase signal θ c of output rotor inferred position.Rotor-position infers that computing utilizes motor constant values such as the internal resistance of the first voltage instruction value Vu*, Vv*, Vw*, alternating current motor 4 and inductance to carry out computing.Voltage instruction generating unit 7 obtains the phase signal θ c of rotor inferred position by infer operational part 10 from rotor-position, determines the phase place of the interchange output of electric power converter main circuit portion 3, carries out the mutual conversion of rotor coordinate system and stator coordinate system.Because the control of position-sensor-free is carried out the position deduction based on the electric current of alternating current motor 4, the precision that therefore detects electric current is very important.

(the 3rd execution mode)

Utilize the pie graph of Fig. 6, the 3rd execution mode of the present invention is described.In Fig. 6, power-converting device 120 appends speed controlling portion 11 and has constituted speed control system on the formation of the power inverter 110 of second execution mode.Speed controlling portion 11 with rotor-position infer the output of operational part 10 be speed inferred value ω c and the speed value ω 1* that applies arbitrarily as input, output d shaft current command value Id* and q shaft current command value Iq*.Speed inferred value ω c becomes the differential value of being inferred the phase signal θ c of the rotor inferred position that operational part 10 calculates by rotor-position.Speed controlling portion 11 is speed value ω 1* and speed inferred value ω c relatively, carries out speed control thus.

In addition, under the situation that constitutes speed control system, rotor angle signal (phase signal) θ of the rotor-position that detection obtains from the rotor-position sensor of installing in alternating current motor 4 12 (with reference to Fig. 1) also can replace speed inferred value ω c and uses this rotor angle signal θ is carried out the speed detected value ω r that differential obtains.In the present embodiment, the torque precision improves because current detection accuracy improves, and therefore, has also improved the tracing ability of speed in the formation of speed control system.As a result, can realize unprecedented speed control response.

(the 4th execution mode)

The 4th execution mode of the present invention is described.The formation of present embodiment is identical with the formation of first execution mode shown in Figure 1, and difference is voltage instruction value generating unit 7.First voltage instruction value in first execution mode is based on by relatively three-phase voltage command value and triangular wave carrier signal, thereby carries out the modulation system of switch transition at the semiconductor element of whole three relative electric power converter main circuit portions 3.But in this modulation system, there is the problem of the switching loss of the semiconductor element that produces three-phase, hinders high-efficient operation sometimes.Therefore, general known have by reducing the bi-phase modulated mode that the switch transition number of times reduces the wastage.The bi-phase modulated mode is meant following mode: make the last branch road of a phase or branch road connection down, the residue two-phase is carried out switch transition, reduce switching loss thus, realize high-efficient operation.In the present embodiment, in voltage instruction value generating unit 7, generate the first voltage instruction value Vu*, Vv*, Vw* based on the bi-phase modulated mode.

One consistent with the amplitude of triangular wave carrier signal among the first voltage instruction value Vu* in the present embodiment, Vv*, the Vw*, therefore this phase is not carried out switch transition.Thus, variation has taken place with respect to first execution mode in the waveform of the pulse current of dc bus current IDC.In Fig. 7, be defined as the minimum phase of voltage, the waveform of the dc bus current IDC during expression n=5 mutually with what do not carry out switch transition.Fig. 7 (a) is the waveform of triangular wave carrier signal, and Fig. 7 (b) changes the time of ordinal number k, and Fig. 7 (c) is voltage instruction change value Δ Vuc, and Fig. 7 (d) is dc bus current IDC.In Fig. 7, the voltage maximal phase is the U phase, considers that pulse detects to the voltage maximal phase, and Δ Vuc determines based on formula (5).

According to the waveform of dc bus current IDC shown in Figure 7, as can be known during dull the increasing of the minimum phase pulse spans of voltage and during dull the minimizing and situation about producing.To this, the pulse of voltage maximal phase is pulse of middle generation during each.About the pulse of voltage maximal phase, ordinal number k=3, by adding correction amount Euc, pulse duration becomes Tpw.According to this figure, becoming per 5 of the above voltage maximal phase pulse of minimum pulse width Tpw is that this point of every n generation is identical with first execution mode, but becomes the frequency content of 2/n with respect to the pulse frequency of dc bus current IDC.In addition, the number of the voltage maximal phase pulse that in 1 cycle in voltage instruction change cycle, produces with the pulse duration more than the Tpw in Fig. 7 (d) for symbol 1 this.This number equates with the number that becomes Δ Vuc=Δ Euc, therefore, is two when determining Δ Vuc based on formula (4).

In addition, on the high order harmonic component composition that is applied by voltage instruction changing unit 8, stack is the frequency content in 1 cycle with the voltage instruction change cycle.This is identical with first execution mode.Therefore, the high order harmonic component composition as the formula (7) that also superposeed in the present embodiment.

In addition, only the modulation system of voltage instruction generating unit 7 is different with first execution mode in present embodiment, constitutes identical.Therefore, the mode of present embodiment also may be used in the represented formation of second execution mode and the 3rd execution mode.

(variation)

The present invention is not limited to described execution mode, for example can carry out following various distortion.

(1) described each execution mode is converted to three-phase alternating voltage with direct voltage, but also may be used on three-phase alternating voltage is converted in the circuit of direct voltage.In this case, the direct current of outlet side is detected, reappear the phase current of input side by current detecting part.In addition, the circuit that alternating voltage is converted to direct voltage for example is recorded in the spy and opens in the 2006-67754 communique.

Claims (7)

1, a kind of power inverter comprises: the PWM control part, and it compares three-phase ac signal and triangular wave carrier signal, production burst width modulated ripple; Power converter circuit portion, it drives switch element according to this pulse width modulation ripple, and direct voltage is converted to three-phase alternating voltage; And current detecting part, its direct current input side in this electric power converter circuit part detects dc bus current and reappears phase current;

This power inverter also comprises the voltage instruction changing unit, to change the cycle as voltage instruction during the odd number unit more than 3, during the described unit described triangular wave carrier pitch of signal note increase or dull the minimizing during, and be zero with the mean value of the correction in the described voltage instruction change cycle or be approximately zero corrected signal and be added on the described three-phase ac signal.

2, power inverter according to claim 1 is characterized in that,

In the described voltage instruction odd number correction in the change cycle at least one is used for the conduction period of pulse type electric current that described dc bus current is produced and guarantees to be the width more than the setting, and this correction is the correction of described three-phase ac signal.

3, power inverter according to claim 2 is characterized in that,

The above width of setting of guaranteeing the conduction period of described pulse type electric current is: during constituting the caused ring of switch transition of semiconductor element of described electric power converter circuit part, with the pulse duration that detects after adding up to during sampling that described dc bus current uses keeps.

4, power inverter according to claim 2 is characterized in that,

For n correction in the described voltage instruction change cycle,

The (n+1)/and correction during the 2} described unit is the above correction of described setting, wherein n is a number during the unit of described voltage instruction in the change cycle.

5, power inverter according to claim 2 is characterized in that,

The described voltage instruction odd number in the change cycle is that n first correction and the size of n correction in the correction during the described unit is approximately 1/2 with respect to the size of the correction during other.

6, power inverter according to claim 1 is characterized in that,

Based on the phase current that reappears by described current detecting part, the three-phase current of described electric power converter circuit part output is controlled.

7, power inverter according to claim 1 is characterized in that,

Comprise that also rotor-position infers operational part, it as input, infers the rotor-position of the alternating current motor that is driven by described three-phase alternating voltage with the phase current of described reproduction,

Determine the phase place of described three-phase alternating voltage according to the described rotor-position of inferring.

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