# VbyF Controller

**Libraries:**

Motor Control Blockset /
Controls /
Controllers

## Description

The VbyF Controller block implements V/F (open-loop or scalar) control for a three-phase permanent magnet synchronous motor (PMSM) or an AC induction motor (ACIM).

You can specify reference speed, motor rated speed, number of motor pole pairs, motor rated voltage, minimum block output voltage, as well as number of discrete time steps for initial ramp up as inputs to compute the three-phase voltages that drive the motor.

When you start up the motor, the block uses the
**N _{Ramp}** input to identify the number of block
samples that it needs to gradually ramp up the motor speed to the reference speed.

$${N}_{Ramp}=\frac{{T}_{ramp}}{Discrete\text{\hspace{0.17em}}step\text{\hspace{0.17em}}size\text{\hspace{0.17em}}(s)}$$

The block's output voltage amplitude varies according to the reference motor speed
(*ω _{ref}*), while keeping the ratio of rated
voltage to rated frequency constant.

$${V}_{abc\_amplitude}=\left(\frac{{V}_{rated}}{{f}_{rated}}\right){f}^{ref}=\left(\frac{{V}_{rated}}{{\omega}_{rated}}\right){\omega}_{ref}$$

where:

*V*is the amplitude of the output voltage_{abc_amplitude}**V**._{abc}*V*is the amplitude of rated phase voltage of the motor._{rated}*f*is the rated frequency of the motor._{rated}*f*is the reference frequency of the motor.^{ref}*ω*is the rated speed of the motor._{rated}*ω*is the reference speed of the motor._{ref}

The V/F control technique does not require any feedback from the motor. This control technique ensures a constant stator magnetic flux by keeping the motor phase voltage proportional to its frequency. For more information about this technique, see Open-Loop Motor Control.

**Note**

If you specify 16-bit fixed-point inputs, the block might not produce an accurate output due to insufficient resolution.

## Examples

## Ports

### Input

### Output

## Parameters

## Extended Capabilities

## Version History

**Introduced in R2023b**