# PMSM Mechanical Parameter Estimator

Estimate back EMF constant, rotor inertia, and viscous damping of permanent magnet synchronous motor (PMSM)

*Since R2023a*

**Libraries:**

Motor Control Blockset /
Parameter Estimation /
PMSM Parameter Estimation

## Description

The PMSM Mechanical Parameter Estimator block uses the phase currents and
voltages, DC voltage across the motor, motor position and speed, stator resistance,
*d*-axis inductance, as well as the other test configuration elements to
compute the following mechanical parameters of a PMSM:

Back EMF constant (

*K*)_{e}Rotor inertia (

*J*)Viscous damping (

*B*)

The block runs the motor using closed-loop field-oriented control (FOC) with a limited
speed during which it runs the tests to estimate the back-EMF constant
(*K _{e}*) and viscous damping (

*B*). After a pre-configured duration, the block concludes these tests to compute

*K*and

_{e}*B*, and then, triggers coast-down by shutting down all six inverter switches. The coast-down results in gradual decline in motor speed which eventually reaches zero. The block measures and uses the time to reach zero-speed to calculate rotor inertia (

*J*).

## Examples

## Ports

### Input

### Output

## Extended Capabilities

## Version History

**Introduced in R2023a**