Chapter 9 Inverter Functions
9-5-4
Free V/f
ï‚Ÿ Free V/f is suitable for special motors and other applications where the load varies greatly based
on the rotational speed that require the output voltage to be freely set relative to the output
frequency. It is also useful for manually optimizing voltage characteristics to conserve energy.
ï‚Ÿ When using free V/f, the V/f characteristic can be freely set by setting the voltage and frequency
at seven points.
 Always set the free V/f frequency in the order of f1 ≦ f2 ≦ f3 ≦ f4 ≦ f5 ≦ f6 ≦ f7.
ï‚Ÿ The initial value of all free V/f frequencies is 0 Hz. Set the free V/f in order from 7, to 6, 5, 4, 3,
2, 1.
ï‚Ÿ If the "Control mode selection [A044]
*1
" is set to "[V/f] Free V/f (02)", "Torque boost mode
selection [A041]
*1
", "Base frequency [A003]
*1
" and "Maximum frequency [A004]
*1
" will be invalid,
and the "Free-V/f frequency 7 [b112]
*1
" is treated as the maximum frequency. However, when
[b112] set to less than 30 Hz, the inverter operation is not permitted.
ï‚Ÿ The inverter cannot output a voltage greater than the input voltage or the "Motor rated voltage
[A082]
*1
", even if a higher value is set for voltages 1 through 7. In addition, due care is required
for appropriate characteristic setting, as failure to do so may induce overcurrent during
acceleration/deceleration, or cause vibration in the motor or machine.
*1. "2nd-motor control [SET]" target parameter. The second control parameter is also subject to setting.
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