7.1. Glossary

ADC
analog-to-digital converter
API
Application Programming Interface
BLDC
brushless DC motor — generally used in six-step control. Also known as PMSM
feedback path
The section of the current control loop between ADC inputs and the current controllers, including Park and Clarke transforms. See also FOC block diagram.
FOC
field-oriented control — a type of control scheme for permanent-magnet synchronous motors or induction motors, where the stator field is controlled relative to the rotor field. It generally results in smoother torque, slightly higher efficiency, and higher torque-speed curve, compared to six-step control, but requires a measurement or estimate of rotor position, and is more computationally intensive.
forward path
The section of the current control loop between the output of the current controllers and the transistor gate drives, including inverse Park and Clarke transforms, DC link compensation, zero sequence modulation, and overmodulation. See also FOC block diagram.
HAL
Hardware Abstraction Layer
IPM
interior permanent-magnet motors (see rotor saliency)
IPMSM
interior permanent-magnet synchronous motors (see rotor saliency)
ISR
interrupt service routine
MCAF
Motor Control Application Framework
MIMO
Multi-input, multi-output systems, usually specified and analyzed with state-space equations. See also SISO.
MCAPI
Motion Control API
MTPA
Maximum Torque per Ampere
PIM
Plug-In Module — a small circuit board containing a processor and several passive components (such as bypass capacitors), meant to plug in to one of Microchip’s development boards.
PLL
phase-locked loop — see AN1292 for the Microchip Application Note covering the PLL-style sensorless estimator.
PMSM
permanent-magnet synchronous motor — generally used with FOC. Also known as BLDC.
PWM
pulse-width modulation
QEI
Quadrature Encoder Interface — the name of the hardware encoder counter peripheral in some Microchip devices.
rotor saliency

Permanent magnet synchronous motors can be divided into two types, interior permanent-magnet synchronous motors (IPM or IPMSM) with magnets located inside the rotor, and surface permanent-magnet synchronous motors (SPM or SPMSM) with magnets placed evenly over the surface of the rotor.

These can be distinguished quantitatively through the ratio of the synchronous inductances \(\xi = L_q/L_d\), known as the saliency ratio.

The SPMSM has stator inductance which is independent of rotor position, and has no significant difference between the two synchronous inductances, so \(\xi = L_q/L_d \approx 1\).

The IPMSM has stator inductance which is dependent of rotor position, and has significant difference between the two synchronous inductances, typically with saliency ratio \(\xi = L_q/L_d > 1\).

SISO
Single-input, single-output systems, usually specified and analyzed with state-space equations. See also MIMO.
SMO
sliding-mode observer — see AN1078 for the Microchip Application Note covering the SMO-style sensorless estimator.
SPM
surface permanent-magnet motors (see rotor saliency)
SPMSM
surface permanent-magnet synchronous motors (see rotor saliency)