ACIM Mechanical Parameter Estimator

Estimate rotor inertia and viscous damping of AC induction motor (ACIM)

Since R2023a

• 

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

Description

The ACIM Mechanical Parameter Estimator block uses the phase currents and voltages, DC voltage across the motor, motor speed, magnetizing current, rotor and complete motor resistances, magnetizing and stator leakage inductances, as well as the other test configuration elements to compute the following mechanical parameters of an induction motor:

• Rotor inertia (J)

• Viscous damping (B)

The block runs the motor using closed-loop field-oriented control (FOC) with a limited speed. While running the motor, the block also runs the tests to estimate viscous damping (B). After a preconfigured duration, the block concludes these tests to compute B, and then triggers coast-down by shutting down all six inverter switches. The coast-down results in a gradual decline in the motor speed, which eventually reaches zero. The block measures the time taken by the motor to reach a speed of zero and uses it to calculate the rotor inertia (J).

Examples

Estimate Induction Motor Parameters Using Parameter Estimation Blocks

Uses the parameter estimation blocks provided by Motor Control Blockset™ to estimate these parameters of an AC induction motor (ACIM):

Open Model

Ports

Input

Iabc — Three-phase current response

scalar

The three-phase current response 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 that you provide to the inverter.

Data Types: single

Speed — Rotor speed

scalar

Current motor speed.

Data Types: single

Id0 — Estimated magnetizing current

scalar

Estimated magnetizing current of the induction motor. You can either connect this input port to the Id0 output of the Id0 Estimator block or provide the magnetizing current value manually using a Constant block.

Data Types: single

Rtotal — Sum of stator and inverter-board resistances

scalar

Sum of estimated stator resistance R_s and inverter board resistance. You can either provide this input by utilizing the Rs output of the ACIM Rs Estimator block or provide this value manually using a Constant block.

Data Types: single

Rr — Estimated rotor resistance

scalar

Estimated rotor resistance of the induction motor. You can either connect this input port to the Rr output of the RrL Estimator block or provide the rotor resistance value manually using a Constant block.

Data Types: single

Lm — Estimated magnetizing inductance

scalar

Estimated magnetizing inductance of the induction motor. You can either connect this input port to the Lm output of the RrL Estimator block or provide the magnetizing inductance value manually using a Constant block.

Data Types: single

Lls — Estimated stator leakage inductance

scalar

Estimated stator leakage inductance of the induction motor. You can either connect this input port to the Lls output of the RrL Estimator block or provide the stator leakage inductance value manually using a Constant block.

Data Types: single

StartStop — Control signal for mechanical parameter estimation

logical

Signal that either starts or stops block execution:

• 1 (rising edge of a pulse) — This signal initiates block execution.

• 0 (falling edge of a pulse) — This signal immediately stops block execution and any tests that the block is running. If you interrupt the estimation process abruptly before completion, the block does not compute or output the mechanical parameter values.

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 frequency			Hz
	Nominal motor current			A
	Nominal voltage			V
	Maximum measurable inverter current			A
	Board resistance			ohm
	Current sense gain			A/ADC Count
	Voltage sense gain			V/ADC Count
Elements for estimating magnetizing current Id0	Measurement time			seconds
	Open-loop ramp time			seconds
Elements for estimating motor resistance (Rs)	Estimation time			seconds
	Vd reference voltage 1			PU voltage
	Vd reference voltage 2			PU voltage
Elements for estimating rotor resistance (Rr), magnetizing inductance (Lm), stator leakage inductance (Lls), and rotor leakage inductance (Llr)	Frequency 1 as a ratio of rated frequency			PU frequency
	Frequency 2 as a ratio of rated frequency			PU frequency
	High frequency for Lm			Hz
	Start voltage for voltage sweep			PU voltage
	Voltage step for voltage sweep			PU voltage
	High-frequency injection voltage			PU voltage
Elements for estimating motor inertia (J) and friction constant (B)	Closed-loop speed duration			seconds
	Closed-loop speed			RPM
	Iq Reference current for FOC			PU current
	Proportional gain			-
	Integral gain			-
	Lower speed limit for inertia estimation			RPM
-	Parameter estimation sample time			seconds

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

Data Types: single

Output

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

scalar

Stator reference voltage components along the a, b, and c axes of the abc reference frame.

Data Types: single

J — Estimated rotor inertia

scalar

Estimated inertia of the induction motor (in kg.m²).

Data Types: single

B — Estimated viscous damping

scalar

Estimated viscous damping of the induction motor (in N.s/m).

Data Types: single

InverterEn — Inverter control signal

logical

Signal that switches on or switches off the inverter:

• 1 (logical high) — For the duration when this signal is high, all six switches of the inverter are switched on.

• 0 (logical low) — For the duration when this signal is low, all six switches of the inverter are switched off.

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
status		0	Did not complete mechanical parameter estimation	-
		1	Mechanical parameter estimation completed successfully	-
CoastDownTime			Measured coast-down duration	seconds
Vdq			Voltages across d and q axes	Volts
Idq			Currents across d and q axes	Amperes
VIAlphaBeta			Voltages and currents across α and β axes	Volts, Amperes
SlipPU			Slip in speed (in per-units) during closed-loop operation of motor	-

Data Types: single

Extended Capabilities

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

Version History

Introduced in R2023a