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Research on a New Indirect Space Vector
Over-Modulation Strategy in Matrix
Converter
Abstract:
Traditional SVPWM maximum voltage transfer ratio (VTR, it is the ratio of output
voltage fundamental amplitude to input voltage fundamental amplitude) is 0.866 in
linear modulation region. In this paper output voltage fundamental amplitude and
total harmonic distortion (THD) affected by basic vector and hexagon vector in
traditional indirect SVPWM over-modulation are analyzed. The traditional indirect
SVPWM over-modulation usually focuses on the inverter stage to improve VTR,
and there are few methods considering both of the inverter and rectifier stages to
improve the over-modulation performances of matrix converter (MC) including
output voltage error, output and input currents THDs. A new over-modulation
method based on indirect SVPWM in the paper is presented. Both the output and
input performances of the MC with the proposed and traditional over-modulation
method are emulated and tested. Simulation results indicate that the output voltage
error and input current THD are smaller and lower with the proposed method.
Experimental results verify that theoretical analysis is right and the proposed overmodulation method is feasible.
Existing system:
 There are many modulation strategies for MC. Alesina and Venturini firstly
established a PWM algorithm based on a rigorous mathematical method.
The controlled output voltage, adjustable input power and maximum VTR
0.5 are the main characteristics of the method.
 The method was improved by injecting third harmonic of input and output
waveforms to the desired output voltage, and the maximum VTR was
improved to 0.866. Huber and Borojevic proposed a different waveform
synthesis approach based on the space vector modulation technique by
classifying 27 switch states into three types in: active vector, rotate vector
and zero vector.
 The significant features of this method are controlled input power factor,
independence of input power factor and maximum VTR 0.866. Low VTR of
MC limits its applied area, such as AC motor variable speed drive system,
motor rated voltage is grid voltage, low VTR will lead to output
electromagnetic torque and motor load capacity decreased. It is seen as a
disadvantage of the MC.
 Under the same output power condition as that for a back-to-back converter,
the output current of the MC will be higher than the back-to-back
converters’, which will result in increased motor loss.
Proposed system:
 To overcome the defect of low VTR in the MC, much research has been
devoting to this problem. Different topology circuits have been introduced to
improve VTR by adding extra switches and passive components, but the
complexity was added.
 Another methods by adding extra switches in the input side of the MC and
control the MC into several modes, such as boost and buck-boost, and the
VTR was greater than 1, but in return higher losses were generated due to
the extra switches. A research on dual mode over-modulation method
applied to MC was made in.
 The VTR was improved to 1 and the output voltage harmonic characteristic
was analyzed. Direct SVPWM over-modulation method was researched in .
The VTR was improved by not using zero vector and modifying referenced
output voltage vector angle in different working mode.
 Though the output voltage error is low in the method, output voltage THD is
high and the system computational amount is large. An over-modulation
method based on output voltage fundamental amplitude linear control was
presented in. The desired output voltage was synthesized by inscribed circle
vector and basic vector.
Circuit diagram:
Advantages:
(1) High power density, no bulky DC link component.
(2) Sinusoidal input and output currents.
(3) Adjustable input power factor.
(4) Regeneration capability.
Reference:
[1] X. Li, M. Su, Y. Sun, H. B. Dan, W. J. Xiong, “Modulation strategies
based on mathematical construction for matrix converter extending the
input reactive power range,” IEEE Trans. Pow. Electron., vol. 29, no. 2,
pp. 654–664, Feb. 2014.
[2] M. Hamouda, H. F. Blanchette, K. AI-Haddad, “Indirect matric converter’
enhanced communication method,” IEEE Trans. Ind. Electron., vol. 62,
no. 2, pp. 671–679, Jul. 2015.
[3] T. D. Nguyen, H. H. Lee, “A new SVM method for an indirect matrix
converter with common-mode voltage reduction,” IEEE Trans. Ind.
Informat., vol. 10, no. 1, pp. 61–726, Feb. 2014.
[4] H. W. She, H. Lin, B. He, X. W. Wang, L. M. Yue, X. An,
“Implementation of voltage-based commutation in space-vectormodulated
matrix converter,” IEEE Trans. Ind. Electron., vol. 59, no. 1,
pp. 154–166, Jan. 2012.