
7 Motor control
77
7.1
Motor data
78
7.2
Motor control selection
81
7.2.1
V/f characteristic control
81
7.2.1.1
Linear V/f characteristic
82
7.2.1.2
Square-law V/f characteristic
82
7.2.2
Sensorless vector control (SLVC)
82
7.3
Optimisation of motor control
84
7.3.1
Voltage boost
84
7.3.2
Skip frequencies
84
7.3.3
Optimising the stalling behaviour
86
7.3.4
Slip compensation
87
7.3.5
Oscillation damping
88
7.4
Optimisation of the control loops
89
7.4.1
Speed controller
89
7.4.2
Imax controller
89
7.4.3
Current controller
89
7.5
Motor rotating direction
90
7.6
Switching frequency changeover
91
7.7
Motor protection
92
7.7.1
Motor overload monitoring (i²*t)
92
7.7.2
Current limits
93
7.7.3
Ultimate motor current
94
7.7.4
Motor phase failure detection
94
7.7.5
Motor speed monitoring
95
Contents
4
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