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Fig. 1.
The EMFs and stator currents
2.2 Modulation for IMC
MCs can be divided into two types- Direct Matrix Converter (DMC) and Indirect
Matrix Converter (IMC). In this paper, IMC is used. IMC is divided into rectifier
stage and inverter stage. The rectifier stage is composed of six bi directional
switches and the inverter stage is the same with traditional AC-DC-AC power
converter.In this paper, BLDCM is fed by IMC. As is shown in Figure 2.
d
1
,
2
=
−u
b,c
/u
a
=
−
cos
θ
b,c
/
cos
θ
a
.
(3)
Under balanced input conditions , the mean value of DC voltage in a PWM
period is
u
dc
=
d
ab
u
ab
+
d
ac
u
ac
=3
U
im
/
2
|
cos
θ
a
|
(4)
The other five sectors are similar to sector 1. The mean value of DC voltage is
u
dc
=3
U
im
/
2
|
cos
θ
in|
(5)
3 Closed-Loop Control System for IMC-Fed BLDCM
Drive
The rectifier stage uses PWM modulation while the inverter stage provides with
3-phase symmetry square wave current with the width of 120 electrical degrees.
There are two feedback loops in the system. The inner loop is called speed
loop while the outer loop is called position loop. Firstly, the actual position is
compared with the command position and the error between the two is regulated
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