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)

ZS/MT

Zero-Speed / Maximum Torque estimator