Mitsubishi Electric 800 Series Instruction Manual (Function page 223

• When the carrier frequency automatic reduction function is used, operation with the carrier frequency set to 3 kHz or higher
(Pr.72 ≥ 3) automatically reduces the carrier frequency for heavy-load operation as shown below.
Pr.260 setting
10
0
NOTE
• Reducing the PWM carrier frequency is effective as a countermeasure against EMI from the inverter or for reducing leakage
current, but doing so increases the motor noise.
• When the PWM carrier frequency is set to 1 kHz or lower (Pr.72 ≤ 1), the increase in the harmonic current causes the fast-
response current limit to activate before the stall prevention operation, which may result in torque shortage. In this case,
disable the fast-response current limit in Pr.156 Stall prevention operation selection.
Parameters referred to
Pr.156 Stall prevention operation
Pr.570 Multiple rating settingpage 207
Pr.800 Control method selectionpage 104
222
9. (E) Environment Setting Parameters
9.15 PWM carrier frequency and Soft-PWM control
Pr.570 setting
The carrier frequency will reduce automatically with continuous operation of 85% of the
1 (LD)
inverter rated current or higher.
For the FR-E820-0330(7.5K) or lower, FR-E840-0170(7.5K) or lower, FR-E860-
0120(7.5K) or lower, and FR-E820S-0110(2.2K) or lower, the carrier frequency will
reduce automatically with operation of 170% of the inverter rated current or higher (only
2 (ND) in a low-speed range).
For the FR-E820-0470(11K) or higher and FR-E840-0230(11K) or higher, the carrier
frequency will reduce automatically with operation of 120% of the inverter rated current
or higher.
Without carrier frequency automatic reduction (Perform continuous operation with the
1 (LD) carrier frequency set to 2 kHz or lower or with less than 85% of the inverter rated current
for the ND rating.)
2 (ND) Without carrier frequency automatic reduction
selectionpage 295
Carrier frequency automatic reduction operation