The linear V/f control of the Siemens inverter control algorithm, also known as constant voltage frequency ratio control, is one of the most basic operating modes of the inverter. The following is a detailed explanation of linear V/f control:
1. Basic principles
The V in the V/f control represents the voltage amplitude of the inverter output, and F represents the frequency of the output voltage. The basic principle of linear V/f control is to keep the ratio (V/F) between voltage (V) and frequency (F) constant, so that the magnetic flux of the motor can be kept constant during the speed regulation process, so as to achieve stable output and precise control of torque, and ensure the stable operation and efficient performance of the motor.
2. Features and applications
Features:
High cost performance: Linear V/f control is relatively simple to implement and low cost.
Constant output torque: In the case of constant V/f, the output torque of the motor is relatively stable.
However, the precision of speed control is not high: because it is an open loop control, it is impossible to feedback the motor state in real time, so there may be certain errors in speed control.
Applications:
Linear V/f control is suitable for most motor speed regulation occasions, especially energy-saving inverters such as fans and pumps.
It is also suitable for variable and constant torque loads such as belt conveyors and positive displacement pumps.
3. Parameter setting and adjustment
In Siemens drives, linear V/f control is usually achieved through parameter setting. For example, in the SINAMICS G120 inverter, when selecting linear V/f control, the parameter p1300 needs to be set to 0. In addition, the characteristics of V/f control can be adjusted by other relevant parameters, such as output voltage, output frequency, etc.
4. Precautions
When using linear V/f control, it is necessary to pay attention to the setting of the rated voltage and rated frequency of the motor, which will directly affect the output waveform of the inverter and the performance of the motor.
In low frequency operation, due to the low magnetic flux of the motor, torque compensation may be required to improve the low frequency torque characteristics.
In summary, the linear V/f control of Siemens inverter control algorithm is a simple, practical and widely used motor control method. It is suitable for most motor speed control applications, especially in applications where energy saving and stable torque output are required. However, in cases where speed control accuracy is required, other more advanced control methods may need to be considered.