What is V/F Control?

Electric motors require a specific voltage-to-frequency ratio to operate efficiently and produce adequate power (torque). V/F control ensures this ratio is maintained: as the drive increases frequency for higher speed, it proportionally increases voltage to provide necessary power.

 

The H100+ offers various V/F "patterns" to suit different motor and machine power requirements.

 

Choosing Your V/F Pattern

Select the V/F pattern using parameter BAS-07

BAS-07 (V/F pattern): This parameter defines the V/F characteristic.

 

Here are the main patterns:

 

0 (Linear) Pattern

How it works: Voltage increases directly with frequency.

Best for: Constant torque loads, like conveyor belts, requiring consistent power regardless of speed.

 

1 (Square)or 3 (Square2) Pattern

How it works: Voltage increases slowly at low frequencies, then ramps up faster. 'Square2' is more aggressive for pure fan/pump loads.

Best for: Variable torque loads like fans and pumps, where power needs increase significantly with speed. This pattern can save energy.

 

2 (User V/F) Pattern

How it works: Allows custom voltage-frequency curves by setting specific points.

Best for: Expert users needing precise motor matching or unique application demands, often requiring detailed motor data and complex tuning to prevent issues like overheating.

 

 

 

Selecting the Overall Control Mode (V/F or Slip Compensation)

Beyond just the V/F pattern, the H100+ allows you to choose the fundamental motor control method. This is done using parameter DRV-09 in the DRV (Drive) group:

 

DRV-09 (Control mode): This parameter determines the primary control strategy.

 

0 (V/F): This is the standard V/F control mode, as described above, where the voltage and frequency are directly proportional. It's simple and effective for many applications.

1 (Slip Compen): This activates Sensorless Vector Control (SVC). SVC is a more advanced method that estimates motor speed and torque without a physical sensor, providing better speed regulation and torque control, especially at lower speeds, compared to basic V/F control.

 

Setting Key Frequencies:

 

DRV-18 (Base frequency): The frequency at which your motor receives its full, rated voltage (typically 50 or 60 Hz, matching the motor's nameplate).

DRV-19 (Start frequency): The lowest frequency the drive outputs at startup, aiding smooth motor initiation.