7-4
PM Motor
The 3G3M1 Series provides the PM motor mode.
Synchronous motors (PM motors) that are more efficient than induction motors (IM motors) can be
controlled.
This section describes the PM motor mode.
7-4-1
PM Motor and PM Motor Control
PM Motor
A PM motor (abbreviation for “Permanent Magnet motor”) is a motor that uses permanent magnets for
the motor rotor.
Generally, it is also called a synchronous motor. Compared with induction motors that are used con-
ventionally for the inverter, PM motors allow no current flow on the rotor side, which results in highly
efficient operation due to reduced loss.
In terms of the internal construction, there are various types of PM motors: IPM motors (interior perma-
nent magnet type), SPM motors (surface permanent magnet type), and so on.
PM motors have the control characteristics as shown below.
When using the PM motor mode of the 3G3M1 Series Inverter, understand the following characteris-
tics before selecting the inverter type and function settings.
• The applied AC power must be synchronized with the rotor permanent magnets.
Although the motor allows a large current to flow, it cannot output a sufficient torque if the AC power
is not synchronized.
• The permanent magnets used for the rotor are subject to demagnetization if a large current flows in
the PM motor.
Once a rotor is demagnetized, the motor cannot output a sufficient torque and must be replaced.
PM Motor Control
PM motor control with speed feedback can be selected on the 3G3M1 Series.
As large startup torque cannot be output, PM motor control without speed feedback is suitable for ap-
plications with reduced torque characteristics (which do not require torque at low speeds) such as fans
and pumps.
For applications with constant torque characteristics such as general transfer equipment and elevating
axes (which require a torque exceeding the rated torque also at low speeds), select PM motor control
with speed feedback.
In PM motor control without speed feedback, use control with startup torque at 50% or less of the mo-
tor rated torque to keep the PM motor in a synchronized state.
Follow the steps below to use PM motor control.
1. Switch to the PM motor mode (7-4-2 Switching to PM Motor Mode on page 7-21)
2. Execute offline auto-tuning for PM motor parameters (7-8-1 Motor Off-line Auto-tuning on page
7-65)
3. Set PM motor parameters (7-3-2 Motor Parameter Settings on page 7-17)
7 Vector Control and Applied Functions
7-20
M1 Series EtherCAT Type User’s Manual (I670)
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