mcb.getMotorBaseSpeed

Compute base speed for PMSM at rated voltage and rated load

Syntax

base_speed = mcb.getMotorBaseSpeed(pmsm,inverter)

base_speed = mcb.getMotorBaseSpeed(pmsm,inverter,voltEqn)

Description

base_speed = mcb.getMotorBaseSpeed(pmsm,inverter) returns the base speed of a permanent magnet synchronous motor (PMSM) with parameters pmsm and inverter with parameters inverter by using approximate voltage equations.

base_speed = mcb.getMotorBaseSpeed(pmsm,inverter,voltEqn) returns the PMSM base speed by using the specified voltage equations (approximate or actual).

These equations describe the computations that the function performs:

The inverter voltage constraint is defined by computing the d-axis and q-axis voltages using approximate equations:

$v_{do}=- {\omega }_e{L}_q{i}_q$

$v_{qo}={\omega }_e\left(L_d{i}_d+ {\lambda }_{pm}\right)$

$v_{max}= \frac{v_{dc} }{\sqrt{3}} -R_s{i}_{max} \ge \sqrt{v_{do}^2+ v_{qo}^2}$

or actual equations:

$v_{do}=R_s{i}_d- {\omega }_e{L}_q{i}_q$

$v_{qo}=R_s{i}_q-{\omega }_e\left(L_d{i}_d+ {\lambda }_{pm}\right)$

$$v_{max}= \frac{v_{dc} }{\sqrt{3}} \ge \sqrt{v_{do}^2+ v_{qo}^2}$$

The current limit circle defines the current constraint which can be considered as:

$i_{max}^2= i_{d }^2+ i_q^2$

In the preceding equation, $i_d$ is zero for surface PMSMs. For interior PMSMs, values of $i_d$ and $i_q$ corresponding to MTPA are considered.

Using the preceding relationships, we can compute the base speed as:

$${\omega }_{base}= \frac{1}{p}\cdot \frac{v_{max}}{\sqrt{{\left(L_q{i}_q\right)}^2+{\left(L_d{i}_d+ {\lambda }_{pm}\right)}^2}}$$

where:

• ${\omega }_e$ is the electrical speed corresponding to frequency of stator voltages (rad/sec).

• ${\omega }_{base}$ is the mechanical base speed of the motor (rad/sec).

• $i_d$ is the d-axis current (amperes).

• $i_q$ is the q-axis current (amperes).

• $v_{do}$ is the d-axis voltage when $i_d$ is zero (volts).

• $v_{qo}$ is the q-axis voltage when $i_q$ is zero (volts).

• $L_d$ is the d-axis winding inductance (henries).

• $L_q$ is the q-axis winding inductance (henries).

• $R_s$ is the stator phase winding resistance (ohms).

• ${\lambda }_{pm}$ is the permanent magnet flux linkage (webers).

• $v_d$ is the d-axis voltage (volts).

• $v_q$ is the q-axis voltage (volts).

• $v_{max}$ is the maximum fundamental line to neutral voltage (peak) supplied to the motor (volts).

• $v_{dc}$ is the dc voltage supplied to the inverter (volts).

• $i_{max}$ is the maximum phase current (peak) of the motor (amperes).

• $$p$$ is the number of motor pole pairs.

Examples

Get PMSM Base Speed Using Approximate Equations

Get parameters for your motor and inverter. This example uses a BLY171D PMSM and DRV8312-C2-KIT inverter.

pmsm = mcb.getPMSMParameters("BLY171D");
inverter = mcb.getInverterParameters("DRV8312-C2-KIT");

Get the base speed using approximate voltage equations.

mcb.getMotorBaseSpeed(pmsm,inverter)

ans =

        5298

Get PMSM Base Speed Using Actual Equations

Get parameters for your motor and inverter. This example uses a BLY171D PMSM and DRV8312-C2-KIT inverter.

pmsm = mcb.getPMSMParameters("BLY171D");
inverter = mcb.getInverterParameters("DRV8312-C2-KIT");

Get the base speed using actual voltage equations.

mcb.getMotorBaseSpeed(pmsm,inverter,"actual")

ans =

        5393

Input Arguments

pmsm — PMSM parameters

struct

PMSM parameters, specified as a struct.

Specify lumped linear parameters with the following required fields:

• Ld — d-axis stator winding inductance (in henries), specified as a scalar

• Lq — q-axis stator winding inductance (in henries), specified as a scalar

• FluxPM — Permanent magnet flux linkage (in webers), specified as a scalar

• p — Number of pole pairs, specified as a scalar

• Rs — Stator resistance (in ohms), specified as a scalar

• B — Viscous damping coefficient (in kg-m²/ sec), specified as a scalar

• I_rated — Rated current (in amperes), specified as a scalar

You can create a structure with lumped linear parameters using mcb.getPMSMParameters.

Alternatively, specify nonlinear lookup table data with the following required fields:

• PMSMLUT.idvec — d-axis current breakpoints (in amperes) of lookup tables, specified as a vector

• PMSMLUT.iqvec — q-axis current breakpoints (in amperes) of lookup tables, specified as a vector

• PMSMLUT.LdTable — d-axis inductance (in henries) lookup table, specified as matrix

• PMSMLUT.LqTable — q-axis inductance (in henries) lookup table, specified as a matrix

• PMSMLUT.FluxPMTable — Permanent magnet flux linkage (in weber) lookup table, specified as a matrix

or the following required fields:

• PMSMLUT.idvec — d-axis current breakpoints (in amperes) of lookup tables, specified as a vector

• PMSMLUT.iqvec — q-axis current breakpoints (in amperes) of lookup tables, specified as a vector

• PMSMLUT.FluxDTable — d-axis flux linkage lookup table, specified as a matrix

• PMSMLUT.FluxQTable — q-axis flux linkage lookup table, specified as a matrix

Whether you specify lumped parameters or lookup tables, the structure can also contain the following optional fields:

• model — Manufacturer's model number, specified as a character vector

• sn — Manufacturer's serial number, specified as a character vector

• J — Motor inertia coefficient (in kg-m²), specified as a scalar

• Ke — Back EMF constant (in volts/krpm), specified as a scalar

• Kt — Torque constant (in Nm/amperes), specified as a scalar

• N_max — Maximum rotor speed (in rpm), specified as a scalar

• PositionOffset — Rotor position offset (in PU), specified as a scalar

• QEPSlits — Number of quadrature encoder pulse (QEP) slits, specified as a scalar

• T_rated — Rated torque (in Nm), specified as a scalar

Data Types: struct

inverter — Inverter parameters

struct

Inverter parameters, specified as a struct. You can create this structure using mcb.getInverterParameters. Specify the structure with the following required field:

• V_dc — DC voltage

The structure can also contain the following optional fields:

• model — Manufacturer's model number, specified as a character vector

• sn — Manufacturer's serial number, specified as a character vector

• I_trip — Maximum permissible inverter current (in amperes), specified as a scalar

• Rds_on — On-state resistance of MOSFETs (in ohms), specified as a scalar

• Rshunt — Shunt resistance for current sensing (in ohms), specified as a scalar

• R_board — Per-phase board resistance seen by motor (in ohms), specified as a scalar

• CtSensAOffset — ADC offset for phase A, specified as a scalar

• CtSensBOffset — ADC offset for phase B, specified as a scalar

• CtSensCOffset — ADC offset for phase C, specified as a scalar

• CtSensOffsetMax — Maximum limit of automatically calibrated ADC offsets for current sensor, specified as a scalar

• CtSensOffsetMin — Minimum limit of automatically calibrated ADC offsets for current sensor, specified as a scalar

• ADCGain — ADC gain factor scaled by SPI, specified as a scalar

• EnableLogic — Type of inverter, specified as one of the following:

  • 1 — Active-high enabled inverter

  • 0 — Active-low enabled inverter

• invertingAmp — Convention for current entering motor, specified as one of the following:

  • 1 — Current entering motor sensed as positive by current sense amplifier

  • –1 — Current entering motor sensed as negative by current sense amplifier

• ISenseVref — Reference voltage of current sensor circuit (in volts), specified as a scalar

• ISenseVoltPerAmp — Current sensor voltage output per ampere of current (in V/A), specified as a scalar

• ISenseMax — Maximum peak-neutral current that can be measured by current sensor (in amperes), specified as a scalar

The following optional fields are not in the structure you create with mcb.getInverterParameters:

• ADCOffsetCalibEnable — Auto-calibration setting for current sense ADCs, specified as one of the following:

  • 1 — Enable auto-calibration

  • 0 — Disable auto-calibration

• SPI_Gain_Setting — SPI hex value encoding op-amp gain, specified as a scalar

Data Types: struct

voltEqn — Voltage equations for calculating speed

"approximate" (default) | "actual"

Voltage equations for calculating base speed, specified as a character vector or string. Specify one of the following:

• "approximate" — Use approximate voltage equations.

• "actual" — Use actual voltage equations.

Output Arguments

base_speed — Motor base speed

scalar

Motor base speed (in rpm), returned as a scalar.

Version History

Introduced in R2020a

R2025a: Renamed from mcb_getBaseSpeed to mcb.getMotorBaseSpeed

The function mcb_getBaseSpeed is now named mcb.getMotorBaseSpeed.