Energy Saving with Inverters

The consumed power of a variable-torque load, such as fans, pumps, and blowers, is proportional to the cube of its rotation speed.

Adjusting the air volume by the inverter rotation speed control can lead to energy savings.

Utilizing the motor capability to the full

Optimum excitation control

Optimum excitation control continuously adjusts the excitation current to an optimum level to provide the highest motor efficiency. With a small load torque, a substantial energy saving can be achieved.
For example, at 4% motor load torque for a general-purpose motor, the motor efficiency under Optimum excitation control is about 30% higher than the motor efficiency under V/F control.

Offline auto tuning

The offline auto tuning function to measure circuit constants of the motor enables optimal operation of motors even when motor constants vary, when a non-Mitsubishi Electric motor is used, or when the wiring distance is long. Sensorless operation can be performed with Mitsubishi Electric general-purpose (induction) and PM motors (MM-EFS, MM-THE4) as well as non-Mitsubishi Electric general-purpose (induction) and PM motors^*2. The tuning function enables the Advanced optimum excitation control of non-Mitsubishi Electric general-purpose (induction) motors^*2, which increases the usability in energy saving applications.

*2: Depending on the motor characteristics, tuning may not be available.

Energy-Saving Functions Suitable for Various Systems

Standby power reduction

• With the 24 VDC external power supply, the input MC signal can be turned OFF after the motor is stopped, and turned ON before activating the motor. The inverter enables self power management to reduce standby power.
• The inverter cooling fan can be controlled depending on the temperature of the inverter heatsink. Also, signals can be output in accordance with the inverter cooling fan operation. When the fan is installed on the enclosure, the enclosure fan can be synchronized with the inverter cooling fan. Extra power consumption when the motor is stopped can be reduced.

Optimum Inverter Capacity Selection

Multiple rating

The rating can be selected between the two types (LD (light duty) or SLD (superlight duty)) depending on the load of the fan/pump to be used. The optimum inverter capacity can be selected suitable for the motor to be used.

For the 200 V class 90K or higher and the 400 V class 75K or higher, a motor with one-rank higher capacity can be combined.

Further Enhanced PID Control and System Cost Reduction

PID multiple loops (two loops)

Two PID operation units are available in the inverter. The inverter can perform PID control of the motor operation and control the external equipment at the same time. The system cost can be reduced because no external PID controller is required for controlling the external equipment.

Direct setting of the PID set point

The PID set point can be set directly from the operation panel. The setting can be easily changed at hand.

Visibility improvement (Option)

With the optional LCD operation panel (FR-LU08), the unit can be changed from "%" to other easy-to-see units.
Maintenance and adjustment is facilitated by using a familiar unit of air volume, temperature, etc. for indication.

Avoidance of rapid acceleration/deceleration using PID action

PID pre-charge function

Before PID action, the water flow to the pipe is controlled by operating the motor at a constant speed until the measured value (pressure, etc.) reaches the set level. This function is used to avoid rapid acceleration/deceleration caused by starting the PID action while the pipe is empty, and prevent a water hammer action, etc.

Water volume control with multiple pumps

Multi-pump function

By controlling the pumps connected in parallel (up to four pumps) by the PID control by one inverter, water volume, etc. can be adjusted.
One of the connected pumps is driven by the inverter. Other pumps are driven by commercial power supply. The number of pumps to be driven by commercial power supply is automatically adjusted according to the water volume.

Pump water volume control

PID input pressure control

In order to prevent air intake and cavitation inside the pump, the pump inlet pressure can be controlled so that there is no water shortage.

Detection of mechanical faults

Load characteristics measurement function

The speed/torque relationship is stored while no fault occurs. By comparing the present load status with the stored load characteristics, out-of-range warnings can be output if applicable.
Mechanical faults such as clogging of the filter or breakage of the belt can be easily detected, and maintenance is facilitated.

PLC function in the inverter

• Parameters and setting frequency can be changed at the program. Control programs can be created in sequence ladders using the inverter setup software (FR Configurator2).
• Inverter control such as inverter operations triggered by input signals, signal output based on inverter operation status, and monitor output can be freely customized based on the machine specifications.
• All machines can be controlled by the inverter alone, and control can also be dispersed.
• Time-based operation is possible by using in combination with the real-time clock function (when using an optional LCD operation panel (FR-LU08)).