Mitsubishi Electric 800 Series Instruction Manual (Function page 101

 PM sensorless vector control
• The inverter enables highly efficient motor control and highly accurate motor speed control of a PM (permanent magnet
embedded) motor, which is more efficient than an induction motor.
• A speed detector such as an encoder is not required as the inverter estimates the motor speed by the calculation from the
inverter output voltage and current. The inverter drives the PM motor with the least required current for a load in order to
achieve the highest motor efficiency.
Inverter
Speed
command
Speed/magnetic
pole position
NOTE
• The PM sensorless vector control requires the following conditions.
• For the motor capacity, the rated motor current should be equal to or less than the rated inverter current. (Note that the motor
rated current should be 0.4 kW or higher (0.1 kW or higher for the 200 V class).)
If a motor with substantially low rated current compared with the inverter rated current is used, speed and torque accuracies
may deteriorate due to torque ripples, etc. Set the rated motor current to about 40% or higher of the inverter rated current.
• Offline auto tuning is performed.
• Single-motor operation (one motor to one inverter) is performed.
• The overall wiring length with the motor must be 100 m or less. (For the wiring length, refer to the Instruction Manual
(Connection).)
• A surge voltage suppression filter (FR-ASF/FR-BMF) is not used.
100
4. Control Method
PM sensorless vector control image
Output
voltage
Inverter
Controller
circuit
Magnetic field observer
*1
Virtual motor
*1 A magnetic field observer is a control
Output
method that calculates the motor
current
speed/magnetic pole position based
on the motor voltage and current of a
virtual motor which is set up in the
drive unit.