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Voltage-Source PWM RectifierOperation Characteristics

Voltage-Source PWM RectifierOperation Characteristics
Voltage-Source PWM RectifierOperation Characteristics

V oltage-Source PWM Recti?er–Inverter Based on Direct Power Control and Its Operation

Characteristics

Akira Sato,Member,IEEE,and Toshihiko Noguchi,Senior Member,IEEE

Abstract—This paper describes a novel control strategy of di-rect power-control-based voltage-source pulsewidth modulation (PWM)recti?er–inverter.The key of this strategy is direct selec-tion of a switching state of the PWM recti?er–inverter on basis of instantaneous power errors.A relationship between the instanta-neous power and the switching state of the PWM recti?er–inverter is theoretically analyzed,which is essential to compose a switching-state table.Effectiveness of the proposed technique is examined through several experimental tests,using a1.6-kW prototype.As a result,unity power factor operation is achieved by the proposed method,and the output currents are con?rmed to be sinusoidal waveforms without large distortion under balanced and unbal-anced power-source condition.

Index Terms—Direct power control(DPC),nonlinear con-trol,smoothing capacitor,switching-state table,voltage-source pulsewidth modulation(PWM)recti?er–inverter.

I.I NTRODUCTION

I N general,ac–dc–ac conversion system is extensively used

in a variety of power system applications,industry applica-tions,transportation systems,etc.The ac–dc–ac conversion sys-tem is normally composed of a pulsewidth modulation(PWM) recti?er–inverter system,which requires an energy-buffering device,such as electrolytic capacitor to smooth dc-bus volt-age.Therefore,double-stage power conversion prevents physi-cal size reduction and longer product life of the whole apparatus. In recent years,a direct ac–ac power conversion system,such as matrix converter has attracted great attention and researchers have published a numerous number of papers on the direct ac–ac power conversion[1]–[7].On the other hand,a variety of con-trol techniques of reducing the energy-buffering device of the PWM converters have been proposed in the earlier studies[8]–[12].Feed-forward block of the output active power is adopted to the dc-bus-voltage control loop of the PWM recti?er in a number of proposed methods.The input current commands are calculated according to these control block,and is controlled by proportional–integral(PI)regulator,hysteresis comparator,etc. in stationary reference frame or rotating reference frame.There-

Manuscript received December17,2009;revised March15,2010,May 29,2010,and August28,2010;accepted September30,2010.Date of current version June29,2011.Recommended for publication by Associate Editor J.R. Espinoza.

A.Sato is with the Nagaoka University of Technology,Nagaoka940-2188, Japan(e-mail:asato@mem.iee.or.jp).

T.Noguchi is with the Shizuoka University,Hamamatsu432-8561,Japan (e-mail:ttnogut@ipc.shizuoka.ac.jp).

Digital Object Identi?er10.1109/TPEL.2010.2086488fore,in order to accomplished a minimization of the smoothing capacitor of the PWM converter,these control techniques lead to complicated system.

A number of new control techniques have been proposed to improve the control of the PWM converters with regard to the integration of control and modulation functions,alternate modu-lation schemes,and the sensorless method.The former schemes have the advantage of faster transient response and the pos-sibility of controlling simultaneously more than one variable. As one of these techniques,the authors have proposed a direct torque control(DTC)of the induction motor,which is relay (bang-bang)control of the torque and the?ux by two hysteresis comparators and a switching-state table[13].As a similar con-trol method of DTC algorithm,the authors originally reported a direct power control(DPC)of the voltage-source PWM recti?er in1997IEEE IAS Annual Meeting.In DPC strategy,the instan-taneous active and reactive powers are directly controlled in a manner analogous to torque and?ux control in the induction motor[14].The key features of this method are as follows:

1)no need to implement current minor loops;

2)no need for rotational coordinate transformation;

3)no need to separate PWM modulation block. Therefore,this strategy allows an ultimate high-speed power control response and simple con?guration of the power control system.From these,DPC-based technique has recently attracted signi?cant attention and researchers have explored[15]–[23]. One of the disadvantages of the DPC is variable switching fre-quency[17].In order to solve this problem,space vector mod-ulation(SVM)is adopted to the DPC system[18],[23],and DPC technique using the predictive control scheme has been proposed[22].Furthermore,the DPC techniques are extended to various power conversion systems,such as the wound rotor con?guration[15],the active power?lter[19],and the neutral-point-clamped converter[20],[21].

The authors have intensively been investigating the DPC strat-egy of three-phase power converters and its application to vari-ous power conversion systems,such as the voltage-source PWM recti?er,the current-source PWM recti?er,the multilevel PWM recti?er,and the voltage-source PWM inverter with LC?lters [24]–[26].

This paper presents a novel DPC strategy applied to the ac–dc–ac conversion system,which is composed of the voltage-source PWM recti?er and the voltage-source PWM inverter system with a very small dc-bus capacitor.Particularly,a the-oretical analysis of the relationship between a behavior of the instantaneous active and reactive power and the switching states

0885-8993/$26.00?2011IEEE

Fig.1.Simpli?ed circuit diagram of voltage-source PWM recti?er–inverter. of the PWM recti?er–inverter are focused on,which is an es-sential component to compose a switching-state table in the DPC algorithm.The validity of the proposed technique is ex-amined through experimental tests,using1.6-kW prototype. Consequently,excellent operation characteristics are con?rmed not only in a steady state but also in a transient state.Further-more,operation characteristic under an unbalance power-source condition is also con?rmed.

II.B ASIC P RINCIPLE

A main circuit of the ac–dc–ac converter,which consists of the voltage-source PWM recti?er and the voltage-source PWM inverter with a dc-bus capacitor,is shown in Fig.1,where v r,v s, and v t are the input voltages from a three-phase utility power source,V dc is the dc-bus voltage,and v u,v v,and v w are the output voltages to the load.In the PWM recti?er–inverter,the input active power p rec must be equal to a total of the output active power of the inverter p inv and a time derivative of the energy stored in the dc-bus capacitor p dc.Therefore,it can be expressed as follows:

p rec=p inv+p dc(1) where the main circuit losses of the power converters are ne-glected.The dc-bus capacitor C dc stores an electrostatic energy

of W dc=C d c V2

dc /2.The time derivative of the energy stored

in the dc-bus capacitor p dc is given by

p dc=d

dt

W dc=V dc C dc

dV dc

dt

.(2)

On the other hand,the reactive power of input front end

q rec and the reactive power of output q inv are independent of

each other because the two-stage power conversion system is

separated by the dc-bus,if the time derivative of the dc-bus

energy is small.

In order to achieve sinusoidal input current waveforms in the

case of balanced input voltages,the active and reactive power of

input must be constant.If the inverter controls so that the input

active power p rec may correspond to the output active power

p inv,(1)can be approximated as follows:

p rec≈p inv.(3) From(3),the smoothing capacitor is unnecessary because

power?owing through the dc bus is constant,which makes

p dc≈0,as presented in(2).In other words,a time derivative of the energy stored in the dc-bus capacitor p dc at nearly zero

value can be obtained by reducing the dc-bus capacitor,even

though the dc-bus voltage is?uctuated;hence,all the recti?er has to do is only the input reactive power control because the ac-tive power is determined by the load via the inverter.Therefore, the recti?er controls the reactive power of the input and the in-verter controls the active and reactive power of the output,which leads to the minimization of the smoothing capacitor across the dc bus.

In general,the PWM recti?er is required to obtain a stable voltage fed to a load,and to improve input power factor at the same time.In other words,the PWM recti?er requires two degrees of freedom(DOFs),that is,controlling dc-bus voltage and the reactive power of the input.For this reason,at least two legs need to perform PWM operation in a conventional PWM recti?er.On the other hand,the proposed method-based PWM recti?er needs to control only1DOF,which controls the reactive power of the input.Consequently,the proposed strategy operates a PWM control to only one leg of the three phase legs.

III.C ONTROL M ETHOD

A.System Con?guration

Fig.2(a)shows the system con?guration of a conventional method(a),and Fig.2(b)shows the proposed DPC method. Fig.2(a)is system con?guration of the conventional method of reducing the energy-buffering device,which is based on cur-rent control scheme.The recti?er controls the input current and the dc-bus voltage to achieve a unity power factor,and a sta-ble dc-bus voltage and the inverter control the output current to achieve a sinusoidal waveform.The dc-bus voltage control block demonstrates the reduction of the energy-buffering device by means of adopting a feedforward block of the output power command p?inv,where the output power command p?inv can be obtained from inverter voltage commands v?inv and current-feedback signal i out in the inverter.This output power command p?inv adds an output of dc-bus-voltage control block p?

dc

and this output,i.e.,the active power command of the recti?er p?rec.The input current commands i?in are calculated from the active power command p?rec.Therefore,the conventional control system leads to complicated control system because this system requires the addition of the feed-forward block and the output power calcu-lation to basic control system.On the other hand,the proposed DPC strategy requires none of these special control blocks. Fig.2(b)is the system con?guration of the proposed DPC strategy,where the instantaneous active power and the instan-taneous reactive power are directly controlled in a manner of bang-bang control.

It the?rst place,a control algorithm of the recti?er in Fig.2(b) is explained.The input voltages v r,v s,and v t and input cur-rents i r,i s,and i t are detected to calculate the instantaneous active power p rec and the instantaneous reactive power q rec as feedback signals.These detected three-phase quantities are transformed to two-phase quantities according to following equations:

v iα

v iβ

=

2

3

1?1/2?1/2

3/2?

3/2

?

?

v r

v s

v t

?

?(4)

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Fig.2.System con?gurations of control method for PWM recti?er–inverter.(a)System con?gurations of conventional method.(b)System con?guration of the DPC method.

i iαi iβ

=

2

3

1?1/2?1/2

3/2?

3/2

?

?

i r

i s

i t

?

?.(5)

p rec and q rec are calculated by an inner product and an outer product between the voltage and current vectors,as shown in the following equation,respectively.

p rec q rec

=

v iαv iβ

v iβ?v iα

i iα

i iβ

.(6)

On the other hand,the instantaneous reactive power command q?rec is given from an outside of the system to control the total power factor.If a unity total power factor is required,q?rec must be set at zero.The control error of the reactive power,i.e.,Δq rec=q?rec?q rec,is quantized to generate digital signals S rq with a hysteresis comparator.In addition,a phase angle of the input voltage vector is spatially quantized to six sectorsΘr n by 60?by using several comparators.The quantized sectorsΘr n is mathematically expressed as

(n?2)

π

3

≤Θr n<(n?1)π

3

∵n=1,2,...,6.(7) An appropriate switching state of the recti?er can be deter-mined by a combination of these quantized signals S rq and Θr n.The calculated instantaneous active power p rec is pro-vided to the inverter control block.

On the other hand,the inverter is controlled as follows.The in-stantaneous active power command p?inv and the instantaneous reactive power command q?inv are provided from the output-current-control block,where the output-current control is im-plemented by using the proportional regulator in stationary co-ordinates in order to examine operation characteristics of the

1562IEEE TRANSACTIONS ON POWER ELECTRONICS,VOL.26,NO.5,MAY2011 proposed DPC strategy.The detected output currents i u,i v,and

i w are transformed to two-phase output currents i oαand i oβ

according to the following equation:

i oαi oβ

=

2

3

1?1/2?1/2

3/2?

3/2

?

?

i u

i v

i w

?

?.(8)

The sinusoidal two-phase output current command i?oαand

i?oβare compared with their calculated values i oαand i oβ,re-

spectively.The control errors between them are delivered to proportional current regulators,and their outputs are the in-

verter output voltage commands v?oαand v?

oβ.p?inv and q?inv can

easily obtain with(9)by using the aforementioned v iα,v iβ,i iα, and i iβ,respectively

p?inv q?inv

=

v?oαv?

v?

?v?oα

i oα

i oβ

.(9)

The control error of the active power,i.e.,Δp inv=p?inv?p rec,and the instantaneous reactive power command q?inv are used to generate quantized signals S ip and S iq with hysteresis comparators.S ip and S iq correspond to either an ascent mode or a descent mode of the instantaneous power,according to the digital values“1”or“0”.Furthermore,the output current command vector i?o is also quantized to six sectorsΘi n. These digital signals S ip,S iq,andΘi n are used to select the most appropriate switching states of the inverter and to control ON/OFF of each leg.In other words,a combination of S ip,S iq, andΘi n determines the next unique and optimum switching state of the inverter.

https://www.doczj.com/doc/e616392401.html,posing Switching Table

The proposed DPC strategy is,in principle,based on bang-bang control technique of the instantaneous active and reactive power.It is important to investigate the relationship between the switching state of the PWM recti?er–inverter and the polarities of time derivative of the active and reactive power dp/dt and dq/dt in a speci?edΘn.The polarities of dp/dt and dq/dt cor-respond to“1”or“0”of quantized signals S p and S q.According to the time derivatives dp/dt and dq/dt,mathematically solved in term of the switching state of the PWM recti?er–inverter, one of the switching states of the PWM recti?er–inverter must uniquely be determined to restrict the control errors of the active and reactive powerΔp andΔq within the hysteresis bands.

In the following discussion,the time derivatives dp/dt and dq/dt in an exceedingly short time duration,which corresponds to a moment of switching operation,such as several kilohertz operation in the PWM recti?er–inverter,are theoretically inves-tigated.

The time derivative of the reactive power in the recti?er dq rec/dt is derived by using a mathematical model of the recti-?er indicated in Fig.3(a).From this model,the current equation can be written as

L d i in

dt

=v in?v rec.

(10)

Fig.3.Mathematical model of PWM recti?er–inverter.(a)Recti?er model.

(b)Inverter model.

The output voltage vector of the recti?er v rec is de?ned by

the following equation,where V dc is dc-bus voltage:

v rec=

2

3

V dc(S r+S s e j2π/3+S t e j4π/3).(11)

The input voltage vector v in can be expressed as a rotating

vector as follows:

v in=

3V inrms e jθi n(12)

where V inrms is a root-mean-square value of the input line volt-

age.

In an exceedingly short time duration like a switching interval

of the PWM recti?er,a variation of the input voltage vector v in is

negligibly small;hence,v in can approximately be considered

to be a constant value.Therefore,the time derivative of the

reactive power in the recti?er dq rec/dt delivered from(6)can

be approximated as follows:

dq rec

dt

=

d v in

dt

×i in+v in×d i in

dt

≈v in×d i in

dt

.(13)

Substituting((10))–((12))into(13),dq rec/dt is solved as

follows:

dq rec

dt

=

2V inrms V dc

L

(S r2cosθin?S r1sinθin)(14)

∵S r1=S r?1

2

S s?

1

2

S t S r2=

3

2

S s?

3

2

S t

whereθin is an argument of the input line voltage vector v in.

Similarly,the time derivatives of the active and reactive power

in the inverter dp inv/dt and dq inv/dt are delivered by using a

mathematical model of the inverter indicated Fig.3(b).From

this model,the following circuit equation is given:

d i out

dt

=

v inv?v e

L

.(15)

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Fig.4.Calculation results of dq r e c /dt ,dp in v /dt ,and dq in v /dt in Θ1.(a)Calculation results of dq r e c /dt .(b)Calculation results of dp in v /dt and dq in v /dt .

A back electromotive force vector v e is expressed,as a rotating,with an amplitude of √3V e rms and a frequency of ω>,i.e.,

v e =√

3V e rms e j θo u t (16)where θout is an argument of the output current vector i out .

The output voltage vector v inv of the inverter is a function of the switching state as expressed in (17);therefore,

v inv = 2

3V dc (S u +S v e j 2π/3+S w e j 4π/3).(17)A combination of the inverter and an inductance in the current controlled inverter is regarded as a current source;hence,the model of the inverter indicated in Fig.3(b)can be considered the current-source-voltage load.

Since a variation of a back electromotive force vector v e is negligibly small in a short time duration,such as a PWM pulse interval,v e can nearly be regarded as a constant value.Consequently,the time derivatives of the active and reactive power dp inv /dt and dq inv /dt are delivered from (9)as follows:

dp inv dt =d i out dt ·v e +i out ·d v e

dt ≈d i out dt

·v e (18)

TABLE I

S WITCHING -STATE TABLE OF RECTIFIER

.

TABLE II

S WITCHING -STATE TABLE OF INVERTER

.

dq inv dt =d i out dt ×v e +i out ×d v e dt ≈d i out dt

×v e .(19)Substituting ((15))–((17))into (18)and (19),dp inv /dt and dq inv /dt are solved as follows:

dp inv dt =V e rms

L

{?3V e rms +√2V dc (S i 1cos θout +S i 2sin θout )}(20)

dq inv

dt

=√

2V e rms V dc

L

(S i 2cos θout ?S i 1sin θout )(21)

S i 1=S u ?12S v ?1

2S w S i 2=

√32S v ?√

32

S w .Since dq rec /dt ,dp inv /dt ,and dq inv /dt are calculated from (14),(20),and (21),respectively,ascent or descent of the instan-taneous active and reactive power can be found in connection with the switching state of the PWM recti?er–inverter.Fig.4il-lustrates an example of the increasing and decreasing behaviors of the instantaneous power in the sectors Θr 1and Θi 1.The optimum voltage vector of the PWM recti?er–inverter can be selected directly from this illustration.Suppose that one of the voltage vector of the inverter is selected to increase the active power (S ip =“1”)and decrease the reactive power (S iq =“1”),for example.There are two possible voltage vectors v i 1and v i 5in this situation.Selecting one of two vectors can be done by de-termining adjacent output current vector to i ?out ,that is,v i 5.The switching-state table of the PWM recti?er–inverter is composed on the basis of the aforementioned discussion,as indicated in Tables I and II.

IV .E XPERIMENTAL R ESULTS

In order to examine operation characteristics of the proposed DPC-based control of the PWM recti?er–inverter,a 1.6-kW prototype was developed,which constitutes analog and digital mixed signal hardware.Electric parameters of the power circuit are listed in Table III.

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Fig.5.Operation waveforms and frequency spectrum of input current un-der balanced power-source condition.(a)Operation waveforms.(b)Frequency spectrum of input current.

TABLE III

E LECTRIC PARAMETERS O

F MAIN

CIRCUIT

A.Operation Waveforms in Steady State

Fig.5represents several operation waveforms of the proto-type in the steady state,where the load is 1.4kW and average switching frequency of the recti?er and the inverter f rsw and f isw are 8.6kHz and 6.7kHz,respectively.As can be seen,the input current has a sinusoidal waveform similar to the voltage waveform.This unity power factor operation is achieved by giv-ing zero reactive power command.The proposed DPC system makes the line current waveform sinusoidal,although the cur-rent is never directly controlled to be sinusoidal with

current

Fig.6.Output current command step response.(a)operation waveforms.(b)operation waveforms around T in

(a).

Fig.7.

Disturbance step response.

minor loops.On the other hand,the output current waveform is controlled to be sinusoidal waveforms with no large distortion.Furthermore,the dc-bus voltage waveform has a three-phase bridge-recti?ed waveform,which is varied at 300Hz,because the proposed strategy operates so that the maximum and mini-mum phases are in ON state,and the medium phase is pulsewidth modulated.

Fig.6shows a transient response when the output current is changed stepwise between 6.3and 7.5A.As can be seen here,it can be observed that the response time is approximately 0.5ms and excellent transient waveforms are observed without an overshoot,even in this transient state.Fig.7is another transient that shows waveforms in a load step change between 0.92and 1.4kW.The output current is kept almost constant at the com-manded value,even though the sudden load change is applied.As demonstrated in these experimental tests,the DPC system of the PWM recti?er–inverter,which is based on bang-bang con-trol of the instantaneous active and reactive power,functions

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Fig.8.Total

ef?ciency.

Fig.9.Total input power

factor.

Fig.10.

Total harmonic distortion of input current.

quite effectively to achieve a unity power factor operation,to reduce harmonics of the input current,and to obtain the quick responses in regulating the output current.

Figs.8and 9show total ef?ciency and total input power fac-tor of the DPC-based prototype,respectively.Total harmonic distortion is depicted in Fig.10to evaluate quality of the input current waveform.The maximum total input power factor is 99.9%,the maximum total ef?ciency is 95.5%,and total har-monic distortion of the input current is 4.7%at 1.6-kW load.The total input power factor and the total ef?ciency get worse as less load is applied,as shown in Figs.8and 9.This is due to the input current distortion as indicated in Fig.10.Hysteresis bandwidths for the instantaneous active and reactive power in the DPC system are not changed in accordance with the load;thus,the input line currents relatively include more ripples as the load becomes

lighter.

Fig.11.Operation waveforms under unbalanced power-source condition.

B.Operation Characteristics Under Unbalanced Power-Source Condition

Assuming unbalanced power-source condition,operation characteristics of the proposed system are experimentally exam-ined.The unbalanced power-source voltages are v rs =200V ,v st =187V ,and v tr =173V (unbalance ratio is 7.32%),while other test conditions were exactly same as those of Table III.

Fig.11shows the operation waveforms of the PWM recti?er–inverter when the load is 1.2kW and the fast Fourier transform (FFT)analysis results of the input and output currents are in-dicated in Fig.12.As can be seen in Fig.11,the input current waveforms are distorted,but the output current waveforms are well regulated at commanded value without low-frequency large ripples.

The DPC-based PWM recti?er–inverter operates so that the input active power may correspond to the output active power.Therefore,the DPC system carries out to transfer more ac-tive power from ac power-source to load,when the load side goes down,and vice versa .Consequently,the input current waveforms are distorted due to the inclusion of third harmon-ics,which is reluctantly necessary to cancel out the second

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Fig.12.FFT analysis results of input and output currents under unbalanced power-source condition.

harmonics caused by the unbalanced power-source voltages. However,the output currents are stable sinusoidal waveforms with no large distortion.The active and reactive powers of the output are not affected by power-source condition.Therefore, the active and reactive power commands p?inv and q?inv are dc quantities irrespective of the unbalanced power-source condi-tion.As a result,the output currents are controlled to be low distortion and balanced.

From the aforementioned discussion,the proposed DPC strat-egy gives priority to the output control,which is the most sig-ni?cant feature of the DPC system.

V.C ONCLUSION

This paper proposed a novel control strategy of a voltage-source PWM recti?er–inverter with a very small bus capacitor, which features direct control of the instantaneous active and reactive power.The key of this strategy is bang-bang control of the power by means of appropriate selection of the switch-ing state of the PWM recti?er–inverter.In theoretical analysis of the proposed strategy,a relationship between the switching state of the PWM recti?er–inverter and the instantaneous active and reactive power is clari?ed,which leads to composition of the appropriate switching state table in the controller.In addi-tion,feasibility of the proposed system was examined through experimental tests,using a1.6-kW prototype.A result of the test,the proposed system makes it possible to obtain a unity total power factor by setting reactive power command at zero,and low distorted current waveforms are con?rmed.In addi-tion,high-speed response and excellent stability of the output currents are con?rmed in a transient response. Furthermore,operation characteristics under unbalanced power-source condition were experimentally investigated.The proposed DPC technique is capable of regulating the stability of output current suf?ciently without special compensation block, although the power-source voltages are unbalanced.This is the unique feature of the proposed DPC strategy.Future works are the establishment of the optimization design method for the proposed DPC system,such as the parameters of the main cir-cuit and the hysteresis bandwidth,and the improvement of total harmonic distortion in all range.

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1502–1507.

Akira Sato(M’05)was born in Daisen,Japan,in

1979.He received the B.Eng.degree in production

systems engineering from Akita National College

of Technology,Akita,Japan,the M.Eng.degree in

electrical and electronics systems engineering from

Nagaoka University of Technology,Nagaoka,Japan,

and D.Eng.degree in energy and environment en-

gineering from Nagaoka University of Technology,

Nagaoka,Japan,in2002,2004,2009,respectively.

Since2004,he has been with Sanken Electric Co.,

Ltd.,Saitama,Japan.His research interests include static power converters.

Dr.Sato is a member of the Institute of Electrical Engineers,

Japan.

Toshihiko Noguchi(M’95–SM’02)was born in

Kuwana,Japan,in1959.He received the B.Eng.de-

gree in electrical engineering from Nagoya Institute

of Technology,Nagoya,Japan,and the M.Eng.and

D.Eng.degrees in electrical and electronics systems

engineering from Nagaoka University of Technology,

Nagaoka,Japan,in1982,1986,1996,respectively.

In1982,he joined Toshiba Corporation,Tokyo,

Japan.From1991to1993,he was a Lecturer at Gifu

National College of Technology,Gifu,Japan.From

1994to1995,he was a Research Associate and from 1995to2009,he was an Associate Professor in Department of Electrical,Elec-tronics and Information Engineering,Nagaoka University of Technology.Since 2009,he has been a Professor in the Department of Electrical and Electronics Engineering,Faculty of Engineering,Shizuoka University.His research inter-ests include static power converters and motor drives.

Dr.Noguchi is a member of the Institute of Electrical Engineers,Japan.

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湖南科技大学 信息与电气工程学院 《课程设计报告》 题目:转速电流双闭环的数字式可逆直流调速系统的仿真与设计 专业:电气工程及其自动化 班级: 姓名: 学号: 指导教师:

任务书 题 目 转速电流双闭环的数字式可逆直流调速系统的仿真与设计 时 间安排 2013年下学期17,18周 目 的: 应用所学的交、直流调速系统的基本知识与工程设计方法,结合生产实际,确定系统的性能指标与实现方案,进行运动控制系统的初步设计。 应用计算机仿真技术,通过在MATLAB 软件上建立运动控制系统的数学模型,对控制系统进行性能仿真研究,掌握系统参数对系统性能的影响。 在原理设计与仿真研究的基础上,应用PROTEL 进行控制系统的印制板的设计,为毕业设计的综合运用奠定坚实的基础。 要 求:电动机能够实现可逆运行。要求静态无静差。动态过渡过程时间s T s 1.0≤,电流超调量%5%≤i σ,空载起动到额定转速时的转速超调量%30%≤n σ。 总体方案实现:主电路选用直流脉宽调速系统,控制系统选用转速、电流双闭环控制方案。主电路采用25JPF40电力二极管不可控整流,逆变器采用带续流二极管的功率开关管IGBT 构成H 型双极式控制可逆PWM 变换器。其中属于脉宽调速系统特有的部分主要是UPM 、逻辑延时环节DLD 、全控型绝缘栅双极性晶体管驱动器GD 和PWM 变换器。系统中设置了电流检测环节、电流调节器以及转速检测环节、转速调节器,构成了电流环和转速环,前者通过电流元件的反馈作用稳定电流,后者通过转速检测元件的反馈作用保持转速稳定,最终消除转速偏差。 从而使系统达到调节电流和转速的目的。该系统起动时,转速外环饱和不起作用,电流内环起主要作用,调节起动电流保持最大值,使转速线性变化,迅速达到给定值;稳态运行时,转速负反馈外环起主要作用,使转速随转速给定电压的变化而变化,电流内环跟随转速外环调节电机的电枢电流以平衡负载电流。 指导教师评语: 评分等级:( ) 指导教师签名:

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交流伺服电机的工作原理 伺服电机内部的转子是永磁铁,驱动器控制的U/V/W三相电形成电磁场,转子在此磁场的作用下转动,同时电机自带的编码器反馈信号给驱动器,驱动器根据反馈值与目标值进行比较,调整转子转动的角度。伺服电机的精度决定于编码器的精度(线数)。 什么是伺服电机?有几种类型?工作特点是什么? 答:伺服电动机又称执行电动机,在自动控制系统中,用作执行元件,把所收到的电信号转换成电动机轴上的角位移或角速度输出。分为直流和交流伺服电动机两大类,其主要特点是,当信号电压为零时无自转现象,转速随着转矩的增加而匀速下降。 交流伺服电机和无刷直流伺服电机在功能上有什么区别? 答:交流伺服要好一些,因为是正弦波控制,转矩脉动小。直流伺服是梯形波。但直流伺服比较简单,便宜。 永磁交流伺服电动机 20世纪80年代以来,随着集成电路、电力电子技术和交流可变速驱动技术的发展,永磁交流伺服驱动技术有了突出的发展,各国著名电气厂商相继推出各自的交流伺服电动机和伺服驱动器系列产品并不断完善和更新。交流伺服系统已成为当代高性能伺服系统的主要发展方向,使原来的直流伺服面临被淘汰的危机。90年代以后,世界各国已经商品化了的交流伺服系统是采用全数字控制的正弦波电动机伺服驱动。交流伺服驱动装置在传动领域的发展日新月异。永磁交流伺服电动机同直流伺服电动机比较,主要优点有: ⑴无电刷和换向器,因此工作可靠,对维护和保养要求低。 ⑵定子绕组散热比较方便。 ⑶惯量小,易于提高系统的快速性。 ⑷适应于高速大力矩工作状态。 ⑸同功率下有较小的体积和重量。 自从德国MANNESMANN的Rexroth公司的Indramat分部在1978年汉诺威贸易博览会上正式推出MAC永磁交流伺服电动机和驱动系统,这标志着此种新一代交流伺服技术已进入实用化阶段。到20世纪80年代中后期,各公司都已有完整的系列产品。整个伺服装置市场都转向了交流系统。早期的模拟系统在诸如零漂、抗干扰、可靠性、精度和柔性等方面存在不足,尚不能完全满足运动控制的要求,近年来随着微处理器、新型数字信号处理器(DSP)的应用,出现了数字控制系统,控制部分可完全由软件进行的永磁交流伺服系统。 日本安川电机制作所推出的小型交流伺服电动机和驱动器,其中D系列适用于数控机床(最高转速为1000r/min,力矩为0.25~2.8N.m),R系列适用于机器人(最高转速为3000r/min,力矩为0.016~0.16N.m)。之后又推出M、F、S、H、C、G 六个系列。20世纪90年代先后推出了新的D系列和R系列。由旧系列矩形波驱动、8051单片机控制改为正弦

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