Inverter And Converter Configuration; Squirrel Cage Induction Motor Characteristics - YASKAWA VS-626M5 Instruction Manual

Phase−U
voltage signal
Output frequenncy: High
(a)
Output voltage: High
Fig 15.3

15.1.2 Inverter and Converter Configuration

As shown in Fig. 15.4, the configuration consists of a VS-656MR5 Converter, which rectifies a commer-
cial power supply and converts it to direct current, a main circuit capacitor, which smooths the rectified
voltage, and a VS-626M5 Inverter, which converts the direct current to the required AC frequency. The
converter switching element uses IGBT as used by the Inverter.
VS-656MR5 Converter
ACL
3-phase
AC power
supply
Fig 15.4

15.1.3 Squirrel Cage Induction Motor Characteristics

The squirrel cage induction motor characteristics are contrasted with the DC motor and the principle of
torque generation is explained below. Fig. 15.5 shows the model diagrams for each from the direction of
the axis.
Torque occurs in the DC motor using electromagnetic force proportional to the accumulated current that
flows in the armature winding, and the magnetic flux created by the magnetic field current. The torque
generated in this way is easy to control because the magnetic field windings from which the magnetic cur-
rent flows and the armature windings are independent.
On the other hand, the squirrel cage induction motor consists of a rotator with a so-called "squirrel-cage"
construction, and a stator with stator windings. When 3-phase alternating current flows through the stator
windings, a magnetic field of magnetic flux φ
ated by the DC motor magnetic field current.
Magnetic flux φ
I , and is almost equivalent to the unladen current of the squirrel-cage induction motor.
m
Formula: φ
1 cycle
PWM carrier signal
Average output voltage
Sine Wave PWM Control
Main circuit
capacitor
Inverter and Converter Configuration
can be expressed using the following formula. This current is called magnetized current
m
= MI
m m
15 -3
1 cycle
Phase−U voltage signal
Output frequenncy: Low
(b)
Output voltage: Low
VS-626M5 Inverter
P
N
Main circuit
capacitor
is generated. This is equivalent to the magnetic flux gener-
m
15.1 Inverter Drive Basics
Switches
(See Fig.15.2)
S S
1, 4
ON
S
S
2, 3
ON
Induction
motor
15