CN1697307A - Pulse-width modulation type transducer of containing passive filter - Google Patents

Abstract

The frequency converter includes rectifier, inverter, smoothed filter C4, s from first inductor LI to seventh inductor LVII, first capacitor C1, second capacitor C2 and third capacitor C3, and resistance R. One end of LI, one end of LII, and one end of LIII is connected to inverter respectively. The other end of LI is connected to one end of LIV and one end of C1. The other end of C1 is connected to the other end of C2 and C3 and one end of R etc. through eliminating dv/dt, the invention eliminates harm on motors and quality of energy on power network caused by dv/dt.

Description

The pulse-width modulation type transducer that contains passive filter

Technical field:

The present invention relates to a kind of pulse-width modulation that contains passive filter (PWM) type frequency converter that is used for systems such as Electric Traction and Electric Drive.

Background technology:

Frequency control is a high efficiency, good, the widely used A/C transmission control technology of performance.As realize frequency control control device---frequency converter has been widely used in every field such as industry, agricultural and national defence, will play the part of more and more important role in future world.Yet, frequency converter energy-conservation, improve human habitat, reduce production costs, improve the quality of products and improve and also produced some significant negative effects when huge contribution is made in aspects such as industrial automatization.The develop rapidly of modern power electronic device makes device for power switching, can reach tens kHz as the switching frequency of insulated gate bipolar transistor IGBT, and its quick turn-on and turn-off characteristic makes the output of frequency converter produce very high dv/dt (voltage change ratio).Dv/dt is too high will to produce a series of harm to the frequency converter drive system, can be summarized as follows: (1) is during the high speed break-make of device for power switching, the dv/dt of high frequency can encourage eddy current to cause thermal losses in the electric machine iron core lamination, also can make the copper cash winding of motor consume more energy by kelvin effect, the thermal losses of aggravation motor, cause the power of motor loss to increase, efficient reduces, thereby influences motor performance.When the natural mode shape of the frequency that the high-frequency electromagnetic that produces when frequency converter vibrates and the parts of motor is close, can lure that mechanical resonance and noise take place for it into.Power circuit exists distributed capacitance and motor internal to have parasitic capacitance during (2) owing to high frequency, will produce charging and discharging currents I _1g(I _1gBe called leakage current, this electric current is proportional to dv/dt), flow into ground wire, leakage current is crossed the misoperation that senior general causes motor protective circuit.(3) during the voltage type PWM frequency converter drive motors of high carrier frequency, when the dv/dt of high frequency acts on the motor internal parasitic capacitance, not only can produce charging and discharging currents, but also can be because the cumulative function of electric capacity make armature spindle voltage raise.The two can cause that all lubricating oil film punctures, and produces the spark machined effect, thereby causes the motor bearings premature damage, increases the maintenance cost of motor, influences the normal operation of system; (4) leakage current of frequency from 100kHz to several million range flow back into the three phase mains of system through ground wire, produce high-frequency electromagnetic and disturb (EMI), higher harmonic current forms the harmonic wave pressure drop on line impedance, produce meritorious and reactive loss, influence the power supply grid quality of power supply, cause power supplying efficiency to descend; Also can make protective relaying device because of being disturbed misoperation, influence the normal operation of other electronic equipment on the electrical network, even can cause the damage of equipment; (5) when adopting long line transmission cable between motor and the frequency converter inevitably, as in oil exploitation, papermaking, fields such as mining industry, distributed inductance and distributed capacitance owing to long cable exists will produce the reflected wave phenomenon, and motor side dv/dt is doubled.The dv/dt of common-mode voltage doubles to make above-mentioned harm further to increase the weight of.

Summary of the invention:

The invention provides a kind of pulse-width modulation type transducer that contains passive filter, can eliminate the dv/dt of differential mode voltage and the dv/dt of common-mode voltage simultaneously, thereby eliminate the harm of dv/dt the motor and the electrical network quality of power supply.It comprises rectifier 1, inverter 2 peaceful ripple capacitor C 4, the end of flat wave capacitor C4 connects the cathode output end of rectifier 1 and the electrode input end of inverter 2, the other end of flat wave capacitor C4 connects the cathode output end of rectifier 1 and the negative input of inverter 2, it also comprises the first inductance L I, the second inductance L II, the 3rd inductance L III, the 4th inductance L IV, the 5th inductance L V, the 6th inductance L VI, the 7th inductance L VII, first capacitor C 1, second capacitor C 2, the 3rd capacitor C 3 and resistance R, the end of the first inductance L I, the end of the end of the second inductance L II and the 3rd inductance L III is connected on the three-phase output end of inverter 2, the other end of the first inductance L I connects the end of the 4th inductance L IV and an end of first capacitor C 1, the other end of the second inductance L II connects the end of the 5th inductance L V and an end of second capacitor C 2, the 3rd inductance L III connects the end of the 6th inductance L VI and an end of the 3rd capacitor C 3, the other end of first capacitor C 1 connects the other end of second capacitor C 2, one end of the other end of the 3rd capacitor C 3 and resistance R, the other end of resistance R connects the end of the 7th inductance L VII, the other end of the 7th inductance L VII connects the negative input or the electrode input end of inverter, the 4th inductance L IV, the 5th inductance L V, the 6th inductance L VI and homophase identical with the 7th inductance L VII is wound on the same annular core T, first capacitor C 1, the capacitance of second capacitor C 2 and the 3rd capacitor C 3 equates, the first inductance L I, the second inductance L II is identical with the 3rd inductance L III.LIV when the present invention works, the other end of LV and LVI is connected on respectively on the three-phase power input end of motor, LI, LII, LIII, C1, C2 and C3 constitute the dv/dt that differential mode filter is used for the filtering differential mode voltage, C1, C2, C3, R, LI, LII, LIII, LIV, LV, LVI and LVII constitute the dv/dt that common-mode filter is used for the filtering common-mode voltage, filter in the frequency converter of the present invention can filtering dv/dt, avoided the harm of dv/dt to the motor and the electrical network quality of power supply, and because the 4th inductance L IV, the 5th inductance L V, identical and the homophase of the number of turn of the 6th inductance L VI and the 7th inductance L VII is wound on the same annular core T, the influence that not changed by frequency converter frequency to the inhibitory action of common-mode voltage dv/dt.Reasonable in design, the reliable operation of the present invention has bigger promotional value.

Description of drawings:

Fig. 1 is an electrical block diagram of the present invention, Fig. 2 is the 4th inductance L IV, the 5th inductance L V, the 6th inductance L VI, the 7th inductance L VII and annular core T coiling connection diagram, Fig. 3 is the one phase equivalent circuit figure of differential mode filter of the present invention, Fig. 4 is the common mode equivalent circuit of Fig. 1, Fig. 5 is LIV, LV, the equivalent circuit diagram of the transformer that LVI and LVII form, Fig. 6 is the one phase equivalent circuit figure of Fig. 5, Fig. 7 is the single-phase common-mode voltage equivalent circuit diagram of Fig. 4, Fig. 8 is the equivalent circuit diagram after Fig. 7 eliminates mutual inductance, Fig. 9 is the amplitude-frequency characteristic schematic diagram of the transfer function of filter of the present invention, Figure 10 is not for there being the motor side common-mode voltage schematic diagram of filter in the experiment 1, Figure 11 has used motor side common-mode voltage schematic diagram behind the filter of the present invention in 1 for experiment, Figure 12 is not for there being the motor side differential mode voltage schematic diagram of filter in the experiment 2, Figure 13 has used motor side differential mode voltage schematic diagram behind the filter of the present invention in 2 for experiment, Figure 14 is the motor side common-mode voltage schematic diagram of reactive filter in the experiment 2, and Figure 15 is for having used the motor side common-mode voltage schematic diagram behind the filter of the present invention in the experiment 2.

Embodiment:

Embodiment one: specify present embodiment below in conjunction with Fig. 1 to Figure 15.Present embodiment is by rectifier 1, inverter 2, flat wave capacitor C4, the first inductance L I, the second inductance L II, the 3rd inductance L III, the 4th inductance L IV, the 5th inductance L V, the 6th inductance L VI, the 7th inductance L VII, first capacitor C 1, second capacitor C 2, the 3rd capacitor C 3 and resistance R are formed, the end of flat wave capacitor C4 connects the cathode output end of rectifier 1 and the electrode input end of inverter 2, the other end of flat wave capacitor C4 connects the cathode output end of rectifier 1 and the negative input of inverter 2, the end of the first inductance L I, the end of the end of the second inductance L II and the 3rd inductance L III is connected on the three-phase output end of inverter 2, the other end of the first inductance L I connects the end of the 4th inductance L IV and an end of first capacitor C 1, the other end of the second inductance L II connects the end of the 5th inductance L V and an end of second capacitor C 2, the 3rd inductance L III connects the end of the 6th inductance L VI and an end of the 3rd capacitor C 3, the other end of first capacitor C 1 connects the other end of second capacitor C 2, one end of the other end of the 3rd capacitor C 3 and resistance R, the other end of resistance R connects the end of the 7th inductance L VII, the other end of the 7th inductance L VII connects the negative input or the electrode input end of inverter, the 4th inductance L IV, the 5th inductance L V, the 6th inductance L VI and homophase identical with the 7th inductance L VII is wound on the same annular core T, first capacitor C 1, the capacitance of second capacitor C 2 and the 3rd capacitor C 3 equates, the first inductance L I, the second inductance L II is identical with the 3rd inductance L III.Following surface analysis differential mode filter is to the dv/dt inhibitory action of differential mode voltage: comprise positive and negative preface component (being differential mode voltage) and zero-sequence component (being common-mode voltage) in the output voltage of three-phase voltage type PWM frequency converter, be usually said line voltage, phase voltage, because the voltage that the differential mode voltage of inverter 2 outputs is responded on LVII is zero, be equivalent to resistance R and directly receive on the dc bus between rectifier and the inverter, draw the differential mode one phase equivalent circuit thus as shown in Figure 3.The transfer function of circuit shown in Figure 3 is:

$H=\frac{V_0}{V_1}=\frac{3\mathrm{RCs}+1}{\mathrm{LC}{s}^2+3\mathrm{RCs}+1}=\frac{2{\mathrm{\&zeta;}}_1{\mathrm{\&omega;}}_{1n}s+{\mathrm{\&omega;}}_{1n}^2}{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20051000991400101.png"\; state="\{\{state\}\}">s</figure-callout>}}^2+2{\mathrm{\&zeta;}}_1{\mathrm{\&omega;}}_{1n}s+{\mathrm{\&omega;}}_{1n}^2}$ (1)

Wherein, ξ ₁And ω _1nBe respectively the damping and the resonance angular frequency of differential mode equivalent electric circuit, as the formula (2).

$\left\{\begin{array}{c}{\mathrm{\&zeta;}}_1=\frac{3R}{2}\sqrt{\frac{C}{L}}\\ {\mathrm{\&omega;}}_{1n}=\frac{1}{\sqrt{\mathrm{LC}}}\end{array}\right.$ (2)

Formula (1) has low pass behavior, makes damping ratio ξ by selecting circuit parameter ₁Greater than 1, promptly overdamped circuit can effectively reduce differential mode dv/dt, and then eliminate the harm that overvoltage produces system.The effect of the common-mode filter of following surface analysis in reducing the dv/dt of common-mode voltage: common-mode voltage be three-phase phase voltage and 1/3rd, come the common-mode voltage of equivalent PWM frequency converter output with common-mode voltage source Vcm, the common mode equivalent circuit that then draws Fig. 1 as shown in Figure 4.For the ease of analyzing, with three-phase circuit abbreviation shown in Figure 4 be single phase circuit as shown in Figure 6.In complex frequency domain, the characteristic equation of the common mode transformer among Fig. 5 under the zero initial condition is:

$\left[\begin{array}{c}{V}_1\left(s\right)\\ V_2\left(s\right)\end{array}\right]=\left[\begin{array}{cc}3L_{1}s& 3\mathrm{Ms}\\ 3\mathrm{Ms}& ({\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20051000991400101.png"\; state="\{\{state\}\}">L</figure-callout>}}_2+2M)s\end{array}\right]\left[\begin{array}{c}{I}_1\left(s\right)\\ I_2\left(s\right)\end{array}\right]$ (3)

Wherein: M is the mutual inductance between LIV, LV, LVI, the LVII.

Can draw the equivalent electric circuit of four winding transformers according to formula (3), as shown in Figure 5.Consider R, L, the connected mode of C can obtain the single-phase common mode equivalent circuit of Fig. 5, as shown in Figure 6.Then obtain its equivalent electric circuit by eliminating mutual inductance, as shown in Figure 7 and Figure 8.Get its equation description according to Fig. 7 and Fig. 8 by Circuit theory:

$\left\{\begin{array}{c}\mathrm{Vcm}\left(s\right)=(L+3M)s\&times;I_1\left(s\right)+\mathrm{Vco}\left(s\right)\\ \mathrm{Vco}\left(s\right)=[1/\mathrm{Cs}+3R+3(L_1-M)s]\&times;I_1\left(s\right)\end{array}\right.$

L ₁Be the inductance value of the 7th inductance L VII, C be first capacitor C 1, second capacitor C 2 and the 3rd capacitor C 3 capacitance then transfer function be:

$H_{\mathrm{ov}}\left(s\right)=\frac{\mathrm{Vco}\left(s\right)}{\mathrm{Vcm}\left(s\right)}=\frac{3(L_1-M)C{s}^2+3\mathrm{RCs}+1}{(3{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20051000991400125.png,A20051000991400126.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L)C{s}^2+3\mathrm{RCs}+1}$ (4)

Wherein, k and $M=k\sqrt{L_1{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20051000991400101.png"\; state="\{\{state\}\}">L</figure-callout>}}_2}$ Be respectively the coupling coefficient and the mutual inductance of common mode transformer, L ₂Be the inductance value of the 4th inductance L IV, the 5th inductance L V, the 6th inductance L VI, R is the resistance of resistance R.

In the process of inhibition of common-mode voltage, wish transfer function H _Ov(s) has low-pass characteristic to suppress the radio-frequency component in the common-mode voltage.According to formula (4), the condition that satisfies above-mentioned requirements is:

$L_1-M=L_1-k\sqrt{L_1{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20051000991400101.png"\; state="\{\{state\}\}">L</figure-callout>}}_2}=0$ (5)

Then k=1 and L ₁=L ₂Satisfy following formula, its implication is for satisfying the low-pass characteristic of filter, and the common mode transformer coupling should be very good, and annular core can reach this requirement, and then the turn ratio n of common mode transformer is $n=\sqrt{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20051000991400125.png,A20051000991400126.png"\; state="\{\{state\}\}">L</figure-callout>}}_1/{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20051000991400101.png"\; state="\{\{state\}\}">L</figure-callout>}}_2}=1,$ Mutual inductance is $M=k\sqrt{L_1{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20051000991400101.png"\; state="\{\{state\}\}">L</figure-callout>}}_2}={\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20051000991400125.png,A20051000991400126.png"\; state="\{\{state\}\}">L</figure-callout>}}_1.$

Above-mentioned conclusion is brought in the formula (4):

$H_{\mathrm{ov}}\left(s\right)=\frac{3\mathrm{RCs}+1}{(3{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20051000991400125.png,A20051000991400126.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L)\mathrm{<figure-callout\; id="2"\; label="C\; s"\; filenames="A20051000991400101.png"\; state="\{\{state\}\}">C</figure-callout>}{s}^{}{}^2+3\mathrm{RCs}+1}=\frac{3\mathrm{RCs}+1}{(3{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20051000991400125.png,A20051000991400126.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L)C[{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20051000991400101.png"\; state="\{\{state\}\}">s</figure-callout>}}^2+2{\mathrm{\&zeta;}}_2{\mathrm{\&omega;}}_{2n}s+{\mathrm{\&omega;}}_{2n}^2]}$ (6)

Wherein, ξ ₂And ω _2nBe respectively the damping and the resonance angular frequency of common mode equivalent circuit, as the formula (7).

$\left\{\begin{array}{c}{\mathrm{\&omega;}}_{2n}=\frac{1}{\sqrt{({3\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20051000991400125.png,A20051000991400126.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L)C}}\\ {\mathrm{\&zeta;}}_2=\frac{3R}{2}\sqrt{\frac{C}{(3{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20051000991400125.png,A20051000991400126.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L)}}\end{array}\right.$ (7)

By formula (7) as seen, k=1, n=1 can make transfer function obtain low-pass characteristic, thereby can suppress the radio-frequency component by common mode dv/dt generation.

Filter design procedure of the present invention can be divided into for two steps: at first determine the inductance value L of the first inductance L I, the second inductance L II, the 3rd inductance L III and the capacitance C of first capacitor C 1, second capacitor C 2 and the 3rd capacitor C 3 according to the needs of differential mode dv/dt.This step carries out separately, and its reason is that common mode transformer is to not influence of differential mode dv/dt.Carry out the design of common mode part then.

At first determine cut-off angular frequency f _c: according to defining of cut-off angular frequency $\left|H\left(j{\mathrm{\&omega;}}_c\right)\right|=1/\sqrt{2}$ Determined cut-off angular frequency ω thus _1cSize: ${\mathrm{\&omega;}}_{1c}={\mathrm{\&omega;}}_{1n}\sqrt{(1+2{\mathrm{\&zeta;}}_1^2)+\sqrt{{(1+2{\mathrm{\&zeta;}}_1^2)}^2+1}}$ Dv/dt owing to reduce motor terminal by overdamped circuit obtains cut-off angular frequency ω thus _1cApproximate expression: ${\mathrm{\&omega;}}_{1c}\&ap;{\mathrm{\&omega;}}_{1n}\sqrt{2(1+2{\mathrm{\&zeta;}}_1^2)}$ Being derived as the size that makes filter satisfy the minimum cut-off angular frequency of performance requirement by following formula is

${\mathrm{\&omega;}}_{1c}=2.45{\mathrm{\&omega;}}_{1n}=2.45/\sqrt{\mathrm{LC}}$ (8)

Determining of capacitor C: be generally and make filter that higher output voltage be arranged, value is the 20-60 microfarad.According to formula (8), for making the high-frequency harmonic composition of filter in can the filtering inverter output voltage, cut-off frequency should be much smaller than the switching frequency of inverter, i.e. ω _1c＜＜2 π f _s, generally take away and close 0.2～0.4 of angular frequency, then the size of inductance L is expressed from the next:

$L=(0.2~0.4)\frac{2(1+2{\mathrm{\&zeta;}}_1^2)}{{\left(2\mathrm{\&pi;}{f}_s\right)}^{2}C}$ (9)

Wherein, the general value ξ of damping ratio ₁Be between 5 to 10, f _sIt is the switching frequency of inverter.

By formula (7), wish L ₁Big more, the low-pass characteristic of the transfer function of acquisition is good more.Because the main harmonic frequency of common-mode voltage concentrates on switching frequency and the multiple thereof, obtains equation (10), makes the resonance frequency f of transfer function _2nWell below switching frequency f _s

${\mathrm{\&omega;}}_{2n}=2\mathrm{\&pi;}{f}_{2n}=\frac{1}{\sqrt{(3{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20051000991400125.png,A20051000991400126.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L)C}}<\frac{1}{\sqrt{\mathrm{LC}}}<<2\mathrm{\&pi;}{f}_s$ (10)

According to formula (10), in theory, the resonance of high order harmonic component can not take place, and the resonance of low-order harmonic can produce.But the common-mode voltage of low frequency is little to the influence of motor, at this moment can freely determine L ₁Or L ₂, help to reduce loss, volume and the cost of common mode transformer.

In the experiment, for obtaining higher line voltage in motor terminal, capacitor C often reaches μ F level, and then L is calculated by the method for mentioning in the last joint.Value according to L is determined L ₁Value, shown in (4-23).Above-mentioned all values should satisfy formula (10).

L ₁The value of ≈ (2～3) L (11) R satisfies formula (7):

$R=\frac{2{\mathrm{\&zeta;}}_2}{3}\sqrt{\frac{3{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20051000991400125.png,A20051000991400126.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L}{C}}$ (12)

Experimental analysis:

The simulated conditions of experiment 1 is: the PWM frequency is 4kHz; LI, LII and LIII are 9mH, and C1, C2 and C3 are 60 μ F, and then the differential mode resonance frequency of filter is 217Hz; R is 11 Ω, and LIV, LV, LVI and LVII are 30mH, and then the common mode resonance frequency of filter is 65Hz; Coupling coefficient is 1.Fig. 9 is the amplitude-frequency characteristic of transfer function.From figure, can find out significantly, the filter that the present invention proposes has good low-pass characteristic, be that its high band has good attenuation characteristic, f＞1000Hz section for example, inverter can be produced almost all filterings of common-mode voltage in switching frequency (as 4kHz) place, promptly be suitable for the radio-frequency component in the common-mode voltage that the filtering inverter produces.The motor side common-mode voltage of Figure 10 when not adding any filter, its effective value reaches 151V.The common-mode voltage of motor side when Figure 11 is the band common-mode filter, its effective value is 13V.Compare with Figure 10, effective value has reduced more than 90%, illustrates that institute's filter of carrying effect on the reduction common-mode voltage is remarkable.

The experiment condition of experiment 2 is: the PWM switching frequency is 4kHz, and the cable length between frequency converter and the motor is 100m.The value of inductance, electric capacity and resistance is identical with each condition of experiment 1.Figure 12 is the differential mode voltage oscillogram of motor side when reactive filter, owing to exist the long cable of 100m to be connected in the middle of inverter and the motor, the voltage reflection phenomenon has appearred in motor side, and the line magnitude of voltage of motor side almost doubles, and this will make the insulation life of motor shorten.When after adding filter between motor and the inverter, as shown in figure 13, motor end line voltage waveform is filtered sinusoidal wave.Because the differential mode voltage dv/dt of motor side almost completely eliminates, the voltage reflection phenomenon has not existed, and makes the cable length between motor and the frequency converter unrestricted.Simultaneously, this result illustrates that also the common mode transformer of being carried in the filter does not influence differential mode voltage.Figure 14 and Figure 15 are motor side common-mode voltage measured result.Among Figure 14, when not adding any filter, common-mode voltage is because higher dv/dt has also produced the voltage reflection phenomenon, thereby it will produce bigger shaft voltage and shaft current makes the motor bearings premature damage.Among Figure 15, adopt filter of the present invention after, the dv/dt of common-mode voltage has obviously been reduced and when carrier frequency changed, the filter effect among Figure 15 was still obvious.

Claims (2)

1, the pulse-width modulation type transducer that contains passive filter, it comprises rectifier (1), inverter (2) and flat wave capacitor (C4), one end of flat wave capacitor (C4) connects the cathode output end of rectifier (1) and the electrode input end of inverter (2), the other end of flat wave capacitor (C4) connects the cathode output end of rectifier (1) and the negative input of inverter (2), it is characterized in that it also comprises first inductance (LI), second inductance (LII), the 3rd inductance (LIII), the 4th inductance (LIV), the 5th inductance (LV), the 6th inductance (LVI), the 7th inductance (LVII), first electric capacity (C1), second electric capacity (C2), the 3rd electric capacity (C3) and resistance (R), one end of first inductance (LI), one end of one end of second inductance (LII) and the 3rd inductance (LIII) is connected on the three-phase output end of inverter (2), the other end of first inductance (LI) connects an end of the 4th inductance (LIV) and an end of first electric capacity (C1), the other end of second inductance (LII) connects an end of the 5th inductance (LV) and an end of second electric capacity (C2), the 3rd inductance (LIII) connects an end of the 6th inductance (LVI) and an end of the 3rd electric capacity (C3), the other end of first electric capacity (C1) connects the other end of second electric capacity (C2), one end of the other end of the 3rd electric capacity (C3) and resistance (R), the other end of resistance (R) connects an end of the 7th inductance (LVII), the other end of the 7th inductance (LVII) connects the negative input or the electrode input end of inverter, the 4th inductance (LIV), the 5th inductance (LV), the 6th inductance (LVI) and homophase identical with the 7th inductance (LVII) is wound on the same annular core (T), first electric capacity (C1), the capacitance of second electric capacity (C2) and the 3rd electric capacity (C3) equates, first inductance (LI), second inductance (LII) is identical with the 3rd inductance (LIII).

2, the pulse-width modulation type transducer that contains passive filter according to claim 1, the capacitance C that it is characterized in that first electric capacity (C1), second electric capacity (C2) and the 3rd electric capacity (C3) is the 20-60 microfarad, and first inductance (LI), second inductance (LII) and the 3rd inductance (LIII) inductance value L are: $L=(0.2~0.4)\frac{2(1+2{\mathrm{\&zeta;}}_1^2)}{{\left(2\mathrm{\&pi;}{f}_s\right)}^{2}C},$ The inductance value of the 4th inductance (LIV), the 5th inductance (LV) and the 6th inductance (LVI) is L ₁≈ (2～3) L, the value of resistance (R) is

$R=\frac{2{\mathrm{\&zeta;}}_2}{3}\sqrt{\frac{3L_1+L}{C}}.$

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