Mitsubishi Electric FR-E700EX Manual page 47

Major difference with the AC servo system
Item
Control mode
Encoder
Initial magnetic pole detection
Speed
fluctuation ratio
(Load fluctuation 0
to 100%) temperature: 25±10°C)
Speed control range
Command resolution/encoder resolution
Positioning accuracy
Maximum torque
Dynamic brake
Precautions when replacing
the servo system
The control method is PM sensorless vector control. Several
restrictions are applied because the encoder is not provided and
others.
When using this drive unit and a sensorless PM motor, always check
the machine operation in the actual system.
Restrictions
 In positioning operation, the home position is cleared at servo-OFF
or power-OFF because no sensor (encoder) is provided. Always
perform the home position return again.
 In a low-speed operation or at a stop, torque ripples or uneven
rotation is caused. (The operating conditions and parameter setting
affect these.)
 The positioning accuracy is ±1.8°, and the speed control range is
1:1000. However, a slight vibration at a stop or uneven rotation may
occur due to torque ripples. In such a case, ±1.8° is the average
positioning accuracy, and 1:1000 is the average speed control
range.
The maximum wiring length to the motor is 30m. However, to ensure
the positioning accuracy of ±1.8°, the wiring length must be within
5m and the power supply voltage must be between 200 and 220V.
 The best response level in the middle-speed range or higher is
100Hz, but the response level is decreased (to about 50Hz) in the
low-speed range (0.1kW: 600r/min or lower or 0.2 to 0.75kW: 300r/
min or lower).
 Sensors such as an encoder are not provided.
When mechanical protection is necessary for a position, install such
protection externally.
 No dynamic brake circuit is built in. Prepare a dynamic brake
externally if needed.
 Position deviation or an error may occur due to sudden deceleration
of about 0.05 second or lower (3000r/min  0r/min) or the impact
torque exceeding 100% around the zero speed. Check the
operation, and adjust the deceleration time, speed response level,
and model adaptive control gain as necessary to prevent position
deviation or errors.
49
Sensorless servo
Speed control
Position control
(detection time: about 0.1s)
Digital input ±0.05% or lower
Analog input
(Surrounding air ±0.5% or lower
5120 pulses/rev
(must be provided externally)
JN series
Speed control
Position control
Torque control
Without
Required Not required because the
encoder is provided.
±0.01% or lower
1: 1000
(internal speed command)
131072 pulses/rev
(Incremental)
±1.8°
200%
None
Motor structure (compared with the
servo motor HG-KR)
 The bracket at the non-load side of MM-GKR13 is larger.
(Servo motor: 40, MM-GKR: 43)
 [Reduction gear equipped model] The lengths of the installation
bolts are different.
 [Reduction gear equipped model] The shapes of the gear heads are
different.
Motor specifications (compared
with the servo motor HG-KR)
 The 50W capacity model is not available.
 The continuous rated torque is 90% at 750r/min or lower of MM-
GKR13.
 The maximum torque is smaller.
(Servo motor: 350%, MM-GKR: 200%)
 The maximum rotation speed is slower.
(Servo motor: 6000r/min, MM-GKR: 3000r/min)
 The moment of inertia is different.
(For the model without a reduction gear, the moment of inertia is
lower by 0 to 16%.)
 The recommended load inertia moment ratio (under position control)
is lower.
(Servo motor: 17 to 26 times or lower, MM-GKR: 10 times or lower)
 Although no sensor (encoder) is provided, the IP rating and
environment conditions are the same.
 Note that problems related to the sensor (encoder) do not occur.
 [Reduction gear equipped model] Reduction gear equipped model
has the IP rating of IP44.
Others
 The available power supply input is three-phase 200 to 240V only.
 Only the electronic thermal O/L relay is provided as the temperature
protective function.
(Servo motor: Electronic thermal O/L relay and encoder thermistor,
MM-GKR: Electronic thermal O/L relay)
 In the low-speed range (750r/min or lower for the 0.1kW motor, 300r/
min or lower for the 0.2 to 0.75kW motors.), high-frequency tone is
heard because of the high frequency superposition control.
 The maximum wiring length between the drive unit and motor is
30m.
AC servo
J4 series
Speed control
Position control
Torque control
With
Not required because the
encoder is provided.
±0.01% or lower
— ±0.2% or lower
1: 2000
1: 5000 (analog speed command)
1: 5000
(internal speed command)
4194304 pulses/rev
(absolute)
—
300%
Built-in Built-in
With
—
350%