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:

$v_{d o} = - ω_{e} L_{q} i_{q}$

$v_{q o} = ω_{e} (L_{d} i_{d} + λ_{p m})$

$v_{m a x} = \frac{v_{d c}}{\sqrt{3}} - R_{s} i_{m a x} \geq \sqrt{v_{d o}^{2} + v_{q o}^{2}}$

or actual equations:

$v_{d o} = R_{s} i_{d} - ω_{e} L_{q} i_{q}$

$v_{q o} = R_{s} i_{q} - ω_{e} (L_{d} i_{d} + λ_{p m})$

$v_{m a x} = \frac{v_{d c}}{\sqrt{3}} \geq \sqrt{v_{d o}^{2} + v_{q o}^{2}}$

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

$i_{m a x}^{2} = i_{d}^{2} + i_{q}^{2}$

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:

$ω_{b a s e} = \frac{1}{p} \cdot \frac{v_{m a x}}{\sqrt{{(L_{q} i_{q})}^{2} + {(L_{d} i_{d} + λ_{p m})}^{2}}}$

where:

$ω_{e}$ is the electrical speed corresponding to frequency of stator voltages (rad/sec).
$ω_{b a s e}$ 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).
$v_{d o}$ is the d-axis voltage when $i_{d}$ is zero (volts).
$v_{q o}$ 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).
$λ_{p m}$ is the permanent magnet flux linkage (webers).
$v_{d}$ is the d-axis voltage (volts).
$v_{q}$ is the q-axis voltage (volts).
$v_{m a x}$ is the maximum fundamental line to neutral voltage (peak) supplied to the motor (volts).
$v_{d c}$ is the dc voltage supplied to the inverter (volts).
$i_{m a x}$ is the maximum phase current (peak) of the motor (amperes).
$p$ is the number of motor pole pairs.

example

Examples

collapse all

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

collapse all

`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

collapse all

`base_speed` — Motor base speed
scalar

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

Version History

Introduced in R2020a

expand all

R2025a: Renamed from `mcb_getBaseSpeed` to `mcb.getMotorBaseSpeed`

The function mcb_getBaseSpeed is now named mcb.getMotorBaseSpeed.

mcb.getMotorBaseSpeed

Syntax

Description

Examples

Get PMSM Base Speed Using Approximate Equations

Get PMSM Base Speed Using Actual Equations

Input Arguments

`pmsm` — PMSM parameters
`struct`

`inverter` — Inverter parameters
`struct`

`voltEqn` — Voltage equations for calculating speed
`"approximate"` (default) | `"actual"`

Output Arguments

`base_speed` — Motor base speed
scalar

Version History

R2025a: Renamed from `mcb_getBaseSpeed` to `mcb.getMotorBaseSpeed`

See Also

Topics

mcb.getMotorBaseSpeed

Syntax

Description

Examples

Get PMSM Base Speed Using Approximate Equations

Get PMSM Base Speed Using Actual Equations

Input Arguments

pmsm — PMSM parameters struct

inverter — Inverter parameters struct

voltEqn — Voltage equations for calculating speed "approximate" (default) | "actual"

Output Arguments

base_speed — Motor base speed scalar

Version History

R2025a: Renamed from mcb_getBaseSpeed to mcb.getMotorBaseSpeed

See Also

Topics

`pmsm` — PMSM parameters
`struct`

`inverter` — Inverter parameters
`struct`

`voltEqn` — Voltage equations for calculating speed
`"approximate"` (default) | `"actual"`

`base_speed` — Motor base speed
scalar

R2025a: Renamed from `mcb_getBaseSpeed` to `mcb.getMotorBaseSpeed`