# Lq Estimator

Estimate stator inductance (*L _{q}*) of
permanent magnet synchronous motor (PMSM)

*Since R2023a*

**Libraries:**

Motor Control Blockset /
Parameter Estimation /
PMSM Parameter Estimation

## Description

The Lq Estimator block computes the *q*-axis stator
inductance of a PMSM using the phase currents, stator resistance, and the test configuration
elements.

At first, the block locks the rotor along the *d*-axis by injecting a
constant voltage (*V _{d}*). This ensures that the rotor
remains stationary (aligned with

*d*-axis) during frequency injection. To estimate

*q*-axis stator inductance, the block injects a high-frequency voltage signal along the

*q*-axis and then performs the frequency sweep process by gradually reducing the injected signal frequency using the step size defined by

**Step for frequency sweep (Hz)**parameter. During frequency sweep, the block monitors the magnitude of the motor phase current. When the current magnitude becomes appropriately high or when the injected signal frequency reaches the minimum value (

**Minimum frequency (Hz)**parameter), the block starts the estimation process by injecting a signal with rising frequency having a step size of

**Frequency step size for estimation (Hz)**with number of steps defined by the

**Number of frequencies for estimation**parameter. For details about these parameters, see PMSM Parameter Estimation Configurator.

This image shows the frequency sweep and the incremental steps of rising frequency.

The *L _{q}* estimation process uses the measured
frequency sweep time duration as well as the step size of the changing frequency to estimate
the

*q*-axis stator inductance,

*L*.

_{q}## Examples

## Ports

### Input

### Output

## Extended Capabilities

## Version History

**Introduced in R2023a**