Modulation Strategy to Reduce Common-Mode Voltage for Three-to-Five Phase Indirect Matrix Converter - Intelligent Computing for Sustainable Energy and Environment - page 31

3 The Space Vector Pulse Width Modulation of IMC

It is assumed that, on the input side

u a = U im cos( w i t )
u b = U im cos( w i t 120 ◦ )

u c = U im cos( w i t + 120 ◦ )

− (4)

and on the output side:

u A = U om cos( w o t )
u B = U om cos( w o t

− 2 π/ 5)

u C = U om cos( w o t − 4 π/ 5) (5)

u D = U om cos( w o t − 6 π/ 5)

u E = U om cos( w o t − 8 π/ 5)

U im ,U om : amplitudes of input voltage, output voltage respectively. w i ,w o are
the input and output angular frequencies.

3.1 PWM Method for the Rectifier Stage

The aim of the pulse width modulation of the rectifier is to maintain the maxi-
mum positive voltage in the dc side as well as to maintain the input power factor
as unity. Since the input voltages are balanced, there are two possible conditions
for the input phase voltages to separate six sectors. First, two voltages are pos-
itive, and one is negative. Second, two voltages are negative, and one is positive
[10]. Finally, the average value of the dc voltage during each switch interval is

3 · U im

U dc = (6)

2 ·| cos( θ in ) |

3.2 SVPWM Method for the Inverter Stage

The application of only large space vectors does not produce satisfactory results
in terms of the harmonic content of the output phase voltage. When reference
voltages are sinusoidal, the space vector reference contains only d 1 − q 1 compo-

nents, d 3 − q 3 components are zero. However, if only large vectors are used to

create the desired d 1 −

q 3 voltage components will inevitably
be created as well. Each switching combination that gives a large vector in the
d 1 −

q 1 voltages, d 3 −

q 3 plane. Thus, the
harmonic in output voltage could be restricted to zero by eliminating the voltage
vectors in harmonic space when the output voltage is composed of medium and
large vectors[11]. Fig.3 shows the active and zero space vectors in sector 1. Set the
switch function of matrix converter for inverter side S =[ S A ,S B ,S C ,S D ,S E ].
If S B = 1, it denotes that the upper switch of leg B is ON state, otherwise ,
S B = 0 indicates the lower switch is ON state. Assuming the reference output
voltage space vector V ref is in the sector 1, two neighboring medium and two

q 1 plane gives simultaneously a small vector in the d 3 −