Mitsubishi Electric MELSERVO-J5 User Manual page 182

For linear servo motors
■Thrust and energy calculation
Linear servo motor
secondary side (magnet)
V
M
1
M
2
Linear servo motor
primary side (coil)
Linear servo motor
The following shows formulas of the linear servo motor thrust and energy at the operation pattern above.
Section
(1)
(2)
(3)
(4), (8)
(5)
(6)
(7)
From the calculation results in (1) to (8), find the absolute value (Es) of the sum total of negative energies.
■Losses of servo motor and servo amplifier in regenerative mode
For inverse efficiency and capacitor charging energy, refer to the following.
Page 179 Losses of servo motor and servo amplifier in regenerative mode
■Regenerative energy calculation
Multiply the sum total of regenerative energies by the inverse efficiency, and subtract the capacitor charging from that result to
calculate the energy consumed by the regenerative resistor.
ER [J] = η • E - E
s c
From the total of ERs whose subtraction results are positive and one-cycle period, the power consumption PR [W] of the
regenerative resistor can be calculated with the following equation.
PR [W] = total of positive ERs/one-cycle operation period (tf)
Select a regenerative option based on the PR value. The regenerative option is not required when the energy consumption is
equal to or less than the regenerative power of the regenerative resistor built into the servo amplifier.
6 OPTIONS AND PERIPHERAL EQUIPMENT
180
6.2 Regenerative option
Linear servo motor feed speed
Load
F
t
Thrust F of linear servo motor [N]
F = (M + M ) • V/t + F
1 1 2 psa1 t
F = F
2 1
F = -(M + M ) • V/t + F
3 1 2 psd1 t
F , F = 0
4 8
F = (M + M ) • V/t + F
5 1 2 psa2 t
F = F
6 t
F = -(M + M ) • V/t + F
7 1 2 psd2 t
(2)
V
(1) (3)
Positive
direction
(4)
(5)
t t t t
psa1 1 psd1 2
Energy E [J]
E
1
E
2
E
3
E
4
E
5
E
6
E
7
(8)
Time
Negative
direction
(7)
(6)
t t t t
psa2 3 psd2 4
= V/2 • F • t
1 psa1
= V • F • t
2 1
= V/2 • F • t
3 psd1
, E = 0 (No regeneration)
8
= V/2 • F • t
5 psa2
= V • F • t
6 3
= V/2 • F • t
7 psd2