Performance Optimization of a Square wave operation in an Indirect Matrix Converterwith a Reactor free DC Boost Converter

TECK CHIANG Goh

Performance Optimization of a Square wave operation in an
Indirect Matrix Converter with a Reactor free DC Boost Converter
Goh Teck Chiang
Jun-ichi Itoh
Nagaoka University Of Technology
Nagaoka University Of Technology
Kamitomioka-cho 1603-1
Kamitomioka-cho 1603-1
Nagoaka, Niigata, Japan
Nagoaka, Niigata, Japan
Tel.: +81 / (258) – 479563
Tel.: +81 / (258) – 479563
E-Mail: tcgoh@stn.nagaokaut.ac.jp
E-Mail: itoh@vos.nagaokaut.ac.jp
URL: http://itohserver01.nagaokaut.ac.jp/itohlab/index.html

Keywords«AC/AC Converter», «Induction Motor», «Pulse Width Modulation», «Converter Control», «Matrix
Converter»

Abstract
This paper discusses a modulation control for an indirect matrix converter connects with a reactor
free boost converter for induction motor drives. The square wave modulation is proposed to apply witha four-step commutation pattern to improve the voltage transfer ratio of the indirect matrix converter
from 0.866 to 0.97 (VTR= vout/vin). Furthermore, a feed-forward control is proposed to apply in thereactor free boost converter to reduce the ripple in the battery current which is caused by thefluctuations at the neutral point voltage. In the experiment results, the battery current is reduced byapproximately 72 % by the feed forward control. The loss analysis shows an efficiency of 94 % for the
proposed method.

1. Introduction
Studies and activities in AC/DC/AC interface converters are highly conducting recently. This typeof converters has two AC ports for a generator and a motor, and also a DC port for batteries. Field of
applications are such as hybrid electric vehicle (HEV), wind power generation or smart-grid system.
These power systems require a high efficiency and high reliability converter to convert the energy into
a desired amount for variable speed motor drive.
In order to reduce the cost and size of the power converter, matrix converter has been researched
actively in the AC/DC/AC interface applications. The output voltage of a matrix converter (MC) is
directly converted from the input voltage based on eighteen units of RB-IGBT without the electrolytic
capacitors. However, the lack of electrolytic capacitor results the voltage transfer ratio (VTR) of the
MC is limited by the ratio 0.866 of the input voltage. The hybrid matrix converters were thenintroduced to improve the VTR by using an inverter and a secondary source battery as shown in
Figure 1(a) [1-3]. This kind of circuit topology is suitable for the HEV application. However, the extra
switching devices from the inverter increase the size and cost of this circuit structure.
On the other hand, Figure 1(b) shows the indirect matrix converter (IMC), which has a DC linkpart, is a better circuit structure than the MC in term of size because the DC link part can be connectedwith a standard DC boost converter [4-6]. The authors have proposed a circuit that utilizes the leakage
inductance of a motor to replace the passive component, a boost reactor, in the boost converter by
connecting to the neutral point of the motor, which is shown in Figure 2 [7]. As a result, the circuit isconstructed from silicon components (IGBT) and diodes without any passive components.
However the IMC faces a similar problem with the MC in the VTR. The authors have proposed toapply a square wave modulation in the secondary side of the IMC [8]. The output voltage delivers asquare waveform with higher amplitude than the sinusoidal waveform (PWM) while drive at highoutput frequency.

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Performance Optimization of a Square wave operation in an Indirect Matrix Converterwith a Reactor free DC Boost Converter

TECK CHIANG Goh

This paper discusses about the optimization of the square wave modulation including a four-step
commutation strategy in the IMC [9]. Then, the feed forward control in the boost converter isdiscussed next. In PWM, the operation of the boost converter relies on the zero vectors of the inverter
stage. However zero vector periods do not occur in inverter with the applying of square wave
modulation. The battery current is fluctuating with a frequency three times larger than the output
frequency. A feed forward control is proposed to suppress the battery current ripple [10]. Experimental
results are demonstrated to confirm the validity of these two control methods.

2. Circuit Topology
Figure 2 shows the circuit structure of an indirect matrix converter connects with a reactor freeboost converter at the DC link part of the IMC. The IMC is divided into two stages, where the primarystage consists of twelve units of IGBT and the inverter stage is a voltage source inverter (VSI) whichis constructed by six units of IGBT. The frequency of the DC link voltage is six times of the input
frequency because the use of direct conversion method in the primary stage. Then this DC link voltage
is used for the inverter stage and the boost converter.
As for the structure of the boost converter, the positive polarity of the battery is connecting to thecenter tap of two IGBTs which is connected at the DC link part of the IMC. Then, the negative
polarity of the battery is connecting to the neutral point of the motor. The leakage inductance of the
motor is utilized in the operation of the boost converter. Note that since IMC does not use electrolytic
capacitor in the DC link part, the DC link voltage cannot be controlled and therefore the boost
converter is controlled by an ACR (automatic current regulator) to regulate and transfer the battery
power for the electric motor.

MatrixConverterG

Indirect
MatrixConverter

G
M

P

M

N

Boost
converter

Inverter(a) Hybrid matrix converter(b) Indirect matrix converterwith boost converter
Fig. 1: Configuration of a AC/DC/AC converter.

Boost
InverterConverter stage

Primarystage

spr ssp stp
ir
is
it

Lin

scp

Motor

srp sps spt

iu

srn ssn stn
Cin

snr sns snt

vo

iv
iw

Edc

200V
/ 50 Hzsup svp swp

scn

sun svn swn

75V

ibat

Fig. 2: Configuration of the proposed circuit.

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Performance Optimization of a Square wave operation in an Indirect Matrix Converterwith a Reactor free DC Boost Converter

TECK CHIANG Goh

3. Control Strategy
Figure 3 illustrates the proposed control block diagram fundamentally referring to Ref. 5. The
control is divided into three sections; primary stage, inverter stage and boost converter. In the primarystage, voltages are calculated in absolute values. The switches containing the maximum input voltage
are always turned on. Then, the two remained switching legs that containing the medium phasevoltage and the minimum phase voltage are categorized into switching state. A simple logic selector isused to convert the pulse pattern from the voltage source into a current course. Then, a DC link
voltage contains with six times the input frequency is formed based on the conversion.
The motor control method uses the Volt/Hertz control, which take the speed reference command tovary the voltage and frequency applied to the induction motor. The inverter stage uses a dqo-uvw
transformation to obtain the output voltage commands based on the dq commands (vd and vq) that isreferring to the V/f conversion. The inverter can be controlled by two different modulations based on
the changes of frequency in the transition control.
According to the motor specification (listed in Table III), the rated voltage of the motor is 200 V
and the rated frequency is 50 Hz. Thereby, by applying the V/f constant control to the V/f conversion,
the inverter should be delivering 200 V at 50 Hz. However, the VTR of the indirect matrix converter islimited at 0.866 of the input voltage, which is 173 V and therefore the frequency is limited to 43 Hz.
Moreover, in order to utilize the leakage inductance of the motor in the boost converter, zero vectors
are required in the inverter stage. Therefore, a three-phase modulation is applied in the inverter stage,
however the maximum reference magnitude for the modulation index of the three-phase modulation islower than that of the two-phase modulation. This is further reduces the VTR of the IMC to 0.75 of the
input voltage, and the frequency is limited to 35 Hz (V/f is proportional).
In the design of the transition control, the inverter outputs sinusoidal waveform (PWM) when the
output frequency is lower than 35 Hz and then it transforms into the square wave modulation when the
output frequency is higher than 35 Hz. Square waveform delivers a higher amplitude output voltage
then the PWM hence it improves the VTR. The “mod reader” is used to distinguish between the twomodulation controls and activate the four-step commutation control and feed forward control in the
primary stage and boost converter respectively (0=Off, 1=On).
DC linkripple cal

Primary
controller
ir*
Input
current is*commands i *10 kHzCarrierPulse
pattern
conv.

+-

Single leg
mod.

t

Rec_duty

Max-mid-min
phase
detectionw*

4-stepcom

V/fconversion
Transition
control

Carrier
generator
0/1
Mod.
readerInverter
controller

dq-uvw vv*
vd* conversion
vw*

X

+ Svp
+ Swp
-

X

*

1/s

+ +
+
1/6
Edc 1/vbat
-

PI

Dt
Dt

X

+
-

(a)
Carrier

X+++

Chopper ib*
commands
Boost converter
controller

Srp*
Srp
Spr
Ssp*
Ssp
Sps
0

+
-

Normalized X
factor

Rec_duty

Sup

X

Feed forward
controller

Carrier

Edc

1/X
vu*

vq*

Srp
Spr
Ssp
Sps
Stp
Spt
Srn
Snr
Ssn
Sns
Stn
Snt

Scp

ib

Rec_duty

Srp*
Srp
Spr
Ssp*
Ssp
Sps
Edc
200

4

1

2

3
4

1
3

2

(b)

Fig. 3: Proposed control block diagram.

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Fig. 4: (a) Dead-time pattern(b) Four-step commutation

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Performance Optimization of a Square wave operation in an Indirect Matrix Converterwith a Reactor free DC Boost Converter

TECK CHIANG Goh

The boost converter applies with a PI control to regulate the battery current and adjust the battery
power. The feed forward signal is added into the PI control to suppress the ripple during square wave
modulation. Details of the feed forward will be discussed in section 3(B).

(a) Four-step commutation in the primary stage
The switching units in the primary stage are applied with zero current switching (ZCS), which isfollowing the zero vector periods of the inverter stage during PWM. Once the inverter transforms into
the square wave modulation, zero vectors could not be created and consequently ZCS cannot beapplied in the primary stage. As a result, switching losses occur in the primary stage switching units.
Furthermore, the dead-time periods in the primary stage switches create open circuit periods in the
primary stage and results the DC link voltage fails to establish. This phenomenon is shown in Figure4(a). The DC link voltage occasionally dropping to zero and it is affecting the output voltage even thisis a high switching frequency converter and therefore the VTR is only 0.91 at maximum.
In order to improve the VTR by overcoming the open circuit periods, four-step commutation
switching pattern is proposed. Figure 4(b) shows the 4-step commutation switching pattern applying in
the four of the switching devices in primary stage at per switching time. Each of the leg in primarystage is formed by two units of IGBTs. 4-step commutation will turn on/off these switches by asequence as shown in Figure 4(b) to avoid the open circuit periods. The switching sequence of eachdevice is calculated by an individual counter in FPGA based on the original switching pattern. From
this method, the output voltage is constantly supplied from a sufficient DC link voltage.
The 4-step com block in Figure 3 illustrates the four-step commutation pattern. The Max-mid-min
phase detection detects and categories the input phase voltage into maximum-phase, medium-phaseand minimum phase. In the proposed four-step commutation pattern, the switches contain the
maximum-phase voltage are always turned on. Then, the switches that contain the medium-phasevoltage and the minimum-phase voltage enable the switching patterns.
Figure 5 illustrates the switching patterns among the switching units SRP, SPR, SPS and SSP. SPR
and SRP are the medium-phase voltage, SPS and SSP are the minimum-phase voltage. SPT and STP
are the maximum-phase voltage and the switches are always turned on. The shaded switches show the
IGBT are turning on/off. The upper side of the graph shows the switching pattern from R-phase to Sphase. Then, the lower side of the graph shows the switching pattern from S-phase to R-phase. The
period of each counter is approximately 2.5 us. These switching patterns will prevent the occurrenceof open circuit periods in the primary stage. The results will be demonstrated in the simulation section.

(b) Feed forward control in the boost converter
The reactor free boost converter faces a fluctuation problem during the square wave modulation.
The square wave modulation causes voltage fluctuation at the neutral point voltage. Since the boost
converter is connecting with the neutral point voltage, the fluctuation is directly inflicting into the

Rec_duty > Carrier [R to S]
1
2
SPR

SPS

3
SPS

SPR

SPR

On
SRP

SSP

Off

SSP SRPSRP

4SPS SPRSPSSSP SRP

SSP
On

Off

Rec_duty < Carrier [S to R]
2
1
SPR

SPS

SRP

SSP SRPSPR

3

4SPS SPRSPS SPRSSP SRP

SSP

SPS

Off

On

SRP

SSP
On

Off

Fig. 5: Four-step commutation switching patterns.

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Performance Optimization of a Square wave operation in an Indirect Matrix Converterwith a Reactor free DC Boost Converter

TECK CHIANG Goh

battery current (neutral line current). The frequency of the fluctuation is three times larger than the
output frequency and the amplitude of the fluctuation is 1/6 Edc.
The fundamental output voltage of a square wave is given by
Vuv 

6

(1)
Edc

where Vuv is the output line voltage, and Edc is the DC link voltage.
Each of the output phase voltage based on the neutral point of the DC link voltage is switching at 0 or
180 degree, and the neutral point voltage will be the sum of the three output phase voltage which is+1/6 Edc. Furthermore, the battery voltage needs to meet the following condition,
Edc 1
 Edc  Vbat
2
6
Edc 3Vbat(2)

where Vbat is the battery voltage, and Edc is the DC link voltage.
Knowing the root of the problem is coming from the inverter, a feed-forward control is proposed
to suppress the ripple. The switching signal from the inverter stage is first obtained and thennormalized to apply into the ACR command of the boost converter. The output waveform of the feed
forward control is similar to the neutral point voltage but in a reverse form. This signal is thencancelled with the actual fluctuation waveform in the PI controller.

Table I: Simulation Parameters: Square wave modulation
Input frequency

50 Hz

Output frequency

50 Hz

Output Power

1000 W

Carrier frequency

10 kHzInput voltage

200 V

Input power factor

99 %Battery voltage

75 V

Leakage inductance

5 mH

4. Simulation Results
Table I shows the simulation parameters. This section is divided into 2 parts, where the first partdemonstrates about the effectiveness of the four-step commutation in primary stage. Then the second
part will illustrate the converter performance along with the transition control and the control of feed
forward.

(a) Four-step commutation
Figure 6 shows two simulation results, where (a) is the dead-time switching pattern and (b) is thefour-step commutation pattern. As discussed previously, the DC link voltage Edc drops to zero during
the opening circuit in the primary stage due to the implementation of dead-time. The output current isforced to flow back to the load through the diode of Sun (or other IGBT located at the lower arm of theinverter). As a result, the DC link voltage is interrupted and insufficient voltage is provided for the
inverter stage. However, since this is a high switching frequency converter, voltage distortion does not
happening at the output voltage.
Figure 6(b) shows that by implementing the four-step commutation in the primary stage is proved to
avoid the distortion in the DC link voltage. The four-step commutation enables the output current
returns to the primary stage. As a result, a sufficient DC link voltage is established for the inverter.
Note that in this simulation, the battery current of the boost converter is controlled at 0 A, that is theboost converter outputs zero power. In this circuit, the DC link voltage is not controlled by the boost
converter, DC link voltage is formed by the direct conversion from the primary stage.

(b) Overmodulation and feed forward control
This section discusses the overmodulation in the inverter and the feed forward control in the boost
converter. The simulation parameter is identical to Table I. Figure 7 illustrates the operation between

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Performance Optimization of a Square wave operation in an Indirect Matrix Converterwith a Reactor free DC Boost Converter

1
0
1
0
400

SRP

1

SSP

SRP

0
SPR
1

Dead-time period

0
SSP
1
0

DC link voltage Edc [V]

1

0
10

TECK CHIANG Goh0
DC link current idc [A]SPSFour-step commutation

DC link voltage Edc [V]260220
DC link current idc [A]0Current flows back via Sun
3

6.6
6
Current flows back via Sun00(a) Dead-time switching operation.
(b) Four-step commutation opearation
Fig. 6: Simulation results for the optimization in primary stage.
the PWM and square wave modulation. V/f constant control and three-phase modulation are applied in
the inverter. The output frequency is increased from 10 Hz to 50 Hz constantly proportional to the
output voltage in the simulation result. The transition control, that is the transformation fromsinusoidal wave into square wave, is designed to start at 35 Hz. The inverter is operated with PWM for
operation less than 35 Hz. From 50 Hz onwards the inverter is operated with the square wave
modulation and the output frequency remains at 50 Hz.
The boost converter controls the battery current at three different points to validate the operation.
The effectiveness of the control on the boost converter can be confirmed from the relationships
between the input power and battery power. At point A, the battery power is increased to 375 W,
subsequently the input power is noticed with a reduction in power because the battery power is used tosupply the motor. Then at point B, the battery power is reduced to 75 W, this can confirm that the
boost converter is well under control in the PWM even the output frequency is constantly increasing.
Note that at the low output frequency range, the ripple of the battery current is high because the pulse
width of the zero vector periods is longer than that of the high output frequency range. In the PWM
operation, the duty of the boost converter is depending on the zero vector periods of the inverter [4].
Therefore, if the width of the zero vector pulse is long, the duty of the charge/discharge rate becomes
longer.
Starting from 50 Hz, the inverter is operating at overmodulation and the output voltage turns into asquare wave. At the same time, the feed forward control is applied into the boost converter. Note thatthe feed forward control can take into control immediately after the inverter transformed into thesquare wave modulation. As a result, a sudden spike does not occur at the battery current.
At point C, the battery power is controlled to 375 W again. From the input current waveform, thereduction on the amplitude of the input current can be noticed. This phenomenon indicates that the
boost converter with the implementation of feed forward control is able to control the battery power. A
positive relationship between the battery power and input power is demonstrated.

Table II: Experiment Parameters
Input frequency

50 Hz

Output frequency

50 Hz

LC filter

2.4 kHz

Carrier frequency

10 kHzBattery voltage

75 V

Leakage inductance

4.42 mH

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Performance Optimization of a Square wave operation in an Indirect Matrix Converterwith a Reactor free DC Boost Converter

TECK CHIANG Goh

Table III: Motor Parameters
Induction Motor (Fuji: MLH6085)
Motor Power

750 W

Poles

4/ 50 Hz

Rated Voltage

200 V

Rated RPM

1420

Rated Current

3.6 A

Leakage inductance

4.42 mH

Servo Motor (Fuji: GRK1151A)
Motor Power

1500 W

Rated RPM

2000

Rated Voltage

200 V

Rated Torque7.16 N.m

Rated Current

8.6 A

Max Torque10.8 N.m

Input voltage vr [V]
200
0
-200

Input current ir [A] (LPF)

5
0
-5
300

Output voltage vuv [V] (LPF)

Transition period

0
-300
10

Output current iu [A]

35 Hz

15 Hz

50 Hz

0
-10

Battery current ibat [A]

5
0
1

A
0.25

B
0.5

Time (s)

C
0.75

1.0

Fig. 7: Simulation results with transition control and feed forward control.

5. Experimental Results
Tables II and III show the experiment parameters. This section is divided into two parts to discussand validate the experiment results of the two proposed methods.

(a) Confirmation on the operation of four-step commutation
The circuit was tested with an induction motor as listed in Table III. Figure 8 demonstrates theresults of the four-step commutation switching pattern. Figure 8(a) is the dead-time switching pattern
and it can be noticed the Edc is dropping to zero regularly results the VTR drops to 0.91 (Vrs(rms) /Vuv(rms) = 200 V / 182 V). Figure 8(b) is the four-step commutation switching pattern, the waveform of
the Edc is containing six times of the input frequency and hence the VTR is improved to 0.97 (Vrs(rms) /Vuv(rms) = 200 V / 194 V). Note that the ibat is controlled to 0 A in order to confirm the IMC operation.
Although the VTR is improved by applying the square wave modulation, the input current appears
to be distorted. The distortion in the input current is because of the step waveform from the six-stepEPE 2011 - Birmingham

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TECK CHIANG Goh

output current. The input current can be improved by design a better LC filter with a larger inductancevalue for the IMC.

(b) Confirmation on the operation of feed forward control
Figure 9 demonstrates the operation of the boost converter where ibat is controlled at 4A and fourstep commutation is applied in the primary side. The results in Figure 9(a) did not implement withfeed forward control. As a result, the battery current is vibrating at a frequency of 150 Hz with a peakpeak ripple value of approximately 15 A. In the result of Figure 9(b), the feed forward control isapplied into the boost converter. The result shows the ripple is greatly suppressed by approximately
72 % and the peak-peak ripple value is 4 A under the same condition with Figure 9(a). Furthermore,
the output current is improved significantly due to the reduction of ripple in the battery current. This isbecause in the reactor free boost converter, the output current is consisting of the battery current. The
inverter needs the zero vectors to control the boost converter with the leakage inductance.
Consequently, the battery current is flowing into the inverter stage at every charge/discharge state.
Figure 10 illustrates the stability control of the battery current while the output voltage istransformed from PWM to square wave modulation. The figure is combined with two results where
the left shows the PWM operation at fout = 30 Hz, and the right shows the square wave operation at fout
= 50 Hz. The battery current is stable controlled at 2 A even the modulation is transforming. The
responds of the feed forward is fast because the control is calculated in the DSP (Digital Signal
Processing) controller. The experiment results show that in the square wave modulation, the battery
current is almost equivalent to the PWM.
Figure 11 shows the input current THD and the output current THD experiment results. The blackline illustrates the input current has been improved significantly by 22%. Likewise, the dotted line
DC link voltage Edc [V] 250 [V/div]

DC link voltage Edc [V] 250 [V/div]

Output voltage vuv [V] 250 [V/div]

Output voltage vuv [V] 250 [V/div]

Input current ir [A] 10 [A/div]

Input current ir [A] 10 [A/div]

Output current iu [A]10 [A/div]

10ms

Output current iu [A]10 [A/div](a). Deadtime pattern.
Fig. 8: The Edc waveform of the IMC.

10ms(b) Four-step commutation

Input current ir [A] 10 [A/div]

Input current ir [A] 10 [A/div]

Output voltage vuv [V] 250 [V/div]

Output voltage vuv [V] 250 [V/div]

Output current iu [A]10 [A/div]

Battery current ibat [A] 5 [A/div]

Battery current ibat [A] 5 [A/div]#4. Output current iu [A]10 [A/div]

10ms

10ms

(a). No-feed forward control.
(b). feed forward control.
Fig. 9: The effectiveness of feed forward control in the boost converter.
shows the THD of the output current has been reduced by approximately 38%.

Table IV: Experiment Parameters
PWM (Output frequency = 35 Hz)

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Square wave Modulation (Output frequency = 50Hz)

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Input voltage (line-line RMS)

200 V

Input voltage (line-line RMS)

200 V

Input current

2.65 A

Input current

2.58 A

Output voltage (line-line RMS) 150 V

Output voltage (line-line RMS)

197 V

Output current

3.68 A

Output current

2.89 A

Output power

1000 W

Output power

1000 W

RL load25Ω 5mH

RL Load35 Ω 5mH

Battery power

150 W

Battery power

150 W

Output voltage vuv [V] 250 [V/div]

fout= 30Hz

fout= 50Hz

Input current ir [A] 10 [A/div]
Output current iu [A]10 [A/div]

Battery current ibat [A] 5 [A/div]
10ms

Fig. 10: Comparison between PWM and square wave modulation.

6. Loss Analysis
The total loss of the circuit is analyzed by using PSIM simulator. The analysis is divided into two
modulations, PWM and square wave modulation. The condition is ideal and the parameters are listed
in Table IV. 
Figure 12 shows the analysis result. For PWM, the total loss of the primary stage is approximately
2 %, consists only the conduction loss due to the implement of zero current switching (ZCS). The total
loss of the inverter is 2 %, 0.75 % is the switching loss. The total loss of the boost converter isapproximately 1.2 %.
For the square wave modulation, the total loss of the rectifier is approximately 2.9 %, where 0.7 %is the switching loss. The total loss of the inverter is 1 %, consists of no switching loss due to thesquare waveform. The total loss of the boost converter is similar to PWM, approximately 1.2 %. The
total loss of the converter under a 1-kW is approximately 50 W. Under an ideal condition, theconverter could achieve efficiency approximately 94 %. The boost converter shows no difference interm of loss between these two modulations.

Conclusion
This paper proposes two control methods to optimize the circuit performance while operating insquare wave modulation. The experimental results confirmed the VTR of the IMC can be improved to
0.97 with the four-step commutation switching control in the primary stage. Further, the feed forward
control could suppress the ripple in the battery current by approximately 72%. Hence, THD of theoutput current can be improved by 38%. The analysis also shows a positively high efficiency 94 % for
the propose circuit at square wave modulation.

References[1] Klumpner, C. and Pitic, C. “Hybrid matrix converter topologies: An exploration of benefits”, PESC 2008,
pp.2-8, Rhodes, June 2008

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Performance Optimization of a Square wave operation in an Indirect Matrix Converterwith a Reactor free DC Boost Converter

TECK CHIANG Goh[2] Itoh, J.-i. and Tamura, H. “A novel control strategy for a combined system using both matrix converter andinverter without interconnection reactors”, PESC 2008, pp.1741-1747, Rhodes, June 2008
[3] Pitic, C.I, and Klumpner, C. “A new Matrix Converter- Voltage Source Inverter hybrid arrangement for an
adjustable speed-open winding induction motor drive with improved performance”, PEMD 2008, pp. 60, York,
April 2008[4] Kato, K. and Itoh, J.-i. “Control strategy for a buck-boost type direct interface converter using an indirect
matrix converter with an active snubber”, APEC 2010, pp. 1684, Texas, Feb. 2010[5] Schonberger, J. Friedli, T. Round, S.D. and Kolar, J.W. “An Ultra Sparse Matrix Converter with a Novel
Active Clamp Circuit”, PCC, pp. 784-791, Nagoya, Japan, 2007
[6] Wijekoon, T., Klumpner, C., Zanchetta, P. And Wheeler, P.W. “Implementation of a Hybrid AC-AC Direct
Power Converter with Unity Voltage Transfer”, IEEE Transactions on Power Electronics, pp. 1918, Vol. 23, July
2008.
[7] Goh Teck Chiang, and Itoh, J.-i. “A three-port interface converter by using an indirect matrix converter with
the neutral point of the motor”, ECCE 2009, pp.3282-3289, San Jose, Sept. 2009[8] Goh Teck Chiang, and Itoh, J.-i. “Voltage transfer ratio improvement of an Indirect matrix converter bysingle pulse modulation”, ECCE 2010, pp.1830-1837, Atlanta, Sept. 2010
[9] Lv Hao, Nie Ziling and Zhihao Ye “A New Controlled Commutation Strategies for Matrix Converter”,
International Symposium on ISCSCT 08, pp. 242, Vol. 2, Wuhan, Dec. 2008[10] Itoh, J.-i, and Ohtani, N. “Square wave operation for a single-phase PFC three-phase motor drive system
without a reactor”, International conference on ICEMS 2009, pp. 1, Tokyo, Nov. 2009

THD [%]

60

FF= Feed forward

50

Output current THD (no FF)
Output current THD ( FF)40

Input current THD (no FF)
Input current THD (FF)30 22%
20
38%

10
0

50

150

300
450
Output power [W]

600

750

Fig. 11: THD values for the square wave modulation.
6

Loss [%]

5
Primary4

Pout = 1000 W

Recovery loss
Turn off loss
Turn on loss
Conduction loss
Primary3
Inverter2

Inverter1
Boost converter0

PWM

Boost converter
Square wave

Fig. 12: Loss analysis comparison between PWM and square wave.

EPE 2011 - Birmingham

ISBN: 9789075815153

P.10