PMSM Rs Estimator

Estimate stator resistance (R_s) of permanent magnet synchronous motor (PMSM)

Since R2023a

• 

Libraries:
Motor Control Blockset / Parameter Estimation / PMSM Parameter Estimation

Description

The PMSM Rs Estimator block computes the stator resistance of a PMSM using the phase currents, DC voltage across the motor, and the test configuration elements.

The block injects two voltages V₁ and V₂ for each phase and measures the respective current responses I₁ and I₂ to estimate each phase resistance. It then estimates the motor resistance by averaging the three phase resistances.

Examples

Estimate PMSM Parameters Using Parameter Estimation Blocks

Uses the parameter estimation blocks provided by Motor Control Blockset™ to estimate these parameters of a permanent magnet synchronous motor (PMSM) with a quadrature encoder sensor:

• Open Model

Estimate PMSM Parameters Using Parameter Estimation Blocks on Real-Time Systems

Uses the parameter estimation blocks provided by Motor Control Blockset™ to estimate these parameters of a permanent magnet synchronous motor (PMSM):

• Open Model

Ports

Input

Iabc — Three-phase current response

vector

The three-phase current response (in amperes) of the motor measured by the current sensors.

Note

Providing phase-c current input is optional. The block functionality is not impacted if you do not provide the phase-c current input.

Data Types: single

Vdc — DC link voltage

scalar

DC bus voltage (in volts) that you provide to the inverter.

Data Types: single

StartStop — Control signal for R_s estimation

logical

Signal that either starts or stops R_s estimation:

• 1 (rising edge of a pulse) — This signal initiates the R_s estimation process.

• 0 (falling edge of a pulse) — This signal immediately stops the R_s estimation process. If you interrupt the estimation process abruptly before completion, the block does not compute or output the R_s value.

Data Types: Boolean

Config — Bus signal input

bus

This table summarizes the expected configuration elements in the bus signal input.

Category	Configuration element			Units
Elements for motor and inverter hardware	Number of pole pairs			-
	Rated speed of motor			RPM
	Rated current of motor			A
	Maximum measurable inverter current			A
	Board resistance			ohms
	Current sense gain			A/ADC Count
	Voltage sense gain			V/ADC Count
	Parameter estimation sample time			seconds
Elements for estimating motor inductances (Ld and Lq)	Maximum frequency			Hz
	Minimum frequency			Hz
	Step for frequency sweep			Hz
	Frequency step size for estimation			Hz
	Number of frequencies for estimation			-
Elements for estimating back EMF constant (Ke), motor inertia (J), and friction constant (B)	Back EMF estimation time			seconds
	Back EMF estimation maximum speed limit			RPM
	Specify current controller gains (off/on)			-
	Proportional gain			-
	Integral gain			-
	Iq reference current as a ratio of rated motor current			PU current
	Lower speed limit for inertia estimation			RPM

You can connect this input port to the Config output port of the PMSM Parameter Estimation Configurator block.

Data Types: single

Output

Vabc — a, b, and c-axis stator reference voltage components

vector

Stator reference voltage components along the a, b, and c axes of the abc reference frame. Each voltage component has a range between -1 and 1.

Data Types: single

Rs — Estimated stator resistance

scalar

Estimated stator resistance (in ohms) of the PMSM.

Data Types: single

Log — Debug signals

bus

Debug signals that the block provides for examination. The bus includes these debug signals.

Debug signal			Description	Units
I1			First measured phase current	A
V1			First injected phase voltage	V
I2			Second measured phase current	A
V2			Second injected phase voltage	V
Rs1			Estimated a axis resistance	ohms
Rs2			Estimated b axis resistance	ohms
Rs3			Estimated c axis resistance	ohms
status		0	Rs estimation did not start yet.	-
		1	Rs estimation is in progress.	-
		2	Rs estimation completed successfully.	-
		8000	Rs estimation failed because the current feedback from motor did not increase proportionally to the rise in the injected voltage. Observe all three phase resistances from the log output and if they are in the acceptable range, increase the threshold in the block mask to accommodate the imbalance in resistances.	-
		8001	Rs1 estimation failed due to issues in the Ia phase current. Check if the motor is properly connected and that the ADC is correctly measuring Ia.	-
		8002	Rs2 estimation failed due to issues in the Ib phase current. Check if the motor is properly connected and that the ADC is correctly measuring Ib.	-
		8003	Rs3 estimation failed due to issues in the Ic phase current. Check if the motor is properly connected and that the ADC is correctly measuring Ic.	-

Data Types: single

Parameters

Maximum current limit (A) — Maximum allowed current during testing

15 (default) | scalar

Maximum allowed current (in amperes) during testing.

Step size during injected voltage ramp up (per-unit) — Step size during injected voltage ramp up

0.0001 (default) | scalar

Step size (in per-units) during ramp up of injected voltage.

Maximum voltage ramp up time limit (s) — Maximum voltage ramp up duration

0.25 (default) | scalar

Maximum allowed duration (in seconds) for ramp up of injected voltage.

Number of voltage and current samples per voltage injection instance — Number of voltage and current samples considered for Rs estimation

1000 (default) | scalar

Number of voltage and current samples for each voltage injection that are used for Rs estimation.

Dwell time between voltage injections (s) — Wait duration between voltage injections

0.25 (default) | scalar

Wait duration (in seconds) between successive voltage injections.

Threshold to determine imbalance in phase resistances (0,1) — Threshold to determine phase resistance imbalance

0.2 (default) | scalar

Threshold (specified as a value between 0 and 1) above which to determine the imbalance among the phase resistances.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2023a

R2025a: New block parameters added

The Block Parameters dialog box now includes advanced options for configuring the parameter estimation process.