Mitsubishi Electric FR-A820-00046 Instruction Manual page 232

Control method
PM sensorless vector control
● Highly efficient motor control and highly accurate motor speed control can be performed by using
the inverter with a PM (permanent magnet embedded) motor, which is more efficient than an
induction motor.
● The motor speed is calculated based on the output voltage and current from the inverter. It does
not require a speed detector such as an encoder. The inverter drives the PM motor with the least
required current when a load is applied in order to achieve the highest motor efficiency.
● Performing the IPM parameter initialization makes the IPM motor MM-CF ready for the PM
sensorless vector control.
Fig. 5-1:
A magnetic field observer is a control method that calculates the motor speed/magnetic pole
position based on the motor voltage and current of a virtual motor which is set up in the drive unit.
NOTES The PM sensorless vector control requires the following conditions.
● The motor described in the table below is used.
Motor
Mitsubishi IPM motor (MM-CF)
IPM motor (other than MM-CF), SPM motor
● For the motor capacity, the rated motor current should be equal to or less than the rated
inverter current. (It must be 0.4 kW or higher.)
Using a motor with the rated current substantially lower than the rated inverter current will
cause torque ripples, etc. and degrade the speed and torque accuracies. As a reference, select
the motor with the rated motor current that is about 40% or higher of the rated inverter cur-
rent.
● Single-motor operation (one motor to one inverter) is performed.
● The overall wiring length with the motor is 100 m or less. (Refer to page 2-32.) (Even with the
IPM motor MM-CF, when the wiring length exceeds 30 m, perform offline auto tuning.)
● A surge voltage suppression filter (FR-ASF/FR-BMF) or sine wave filter (MT-BSL/BSC) is not used.
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PM sensorless vector control image
Inverter
Speed
command
Controller
Speed/magnetic
pole position
PM sensorless vector control image
Output
voltage
Inverter
circuit
Magnetic field observer
Virtual motor
Condition
Offline auto tuning is not required
Offline auto tuning is required
Parameters
Output
current
I002500E