# 7.4. Related Documents

More information is available in these other documents, available from Microchip MCU16 Applications on request.

- Hardware Abstraction Layer — This document provides a detailed description of the Hardware Abstraction Layer (HAL), its architecture, components, and usage model. The HAL allows decoupling of the hardware-dependent firmware from the rest of the Motor Control Application Framework, and minimizes the amount of work needed to support additional hardware designs.

- Open to closed loop transitioning module design (startup) — Permanent Magnet Synchronous Motors (PMSM) require precise synchronization between stator flux created by the control electronics (drive) and the rotating permanent magnet flux. If this synchronization is lost, the resulting motor torque exhibits a large oscillatory component and a loss of DC torque. There are a few direct implications:

  - The position of the rotor must be known, in order to determine the required stator field for synchronization
  - The PMSM cannot be operated without a variable frequency drive, since the motor starts from rest and accelerates continuously to the desired operating speed. This requires stator fields to increase frequency continuously along with the rotor, to maintain synchronization

  In case of sensorless drives, the position of the rotor is commonly estimated by using motor’s voltages and currents. At low velocities, these signals are very small, and generally lead to large position uncertainty and loss of synchronization. The design challenges and the solutions to achieve a smooth, robust, and scalable startup sequence, despite these limitations, are presented in this document.

- Monitoring module design (fault detection) — The complexity needed to achieve a field-oriented PMSM motor control system requires a similar level of complexity in fault monitoring, to be able to detect malfunctions in a reliable manner, and determine the underlying cause.

  Mechanical system perturbations are among the most unpredictable, due to their total exposure to the environment, and may be associated with safety hazards to surrounding people or property. Therefore the more accurate and more quickly a mechanical fault can be detected and handled, the more reliably the system can be kept in a safe state. In addition, usually the electronics and mechanical components of a motor-driven system are expensive, so that fault monitoring ultimately has economic advantages.

  This document describes the up-to-date implementation of fault monitoring in the motor control system, capable to distinguish between hazardous and benign situations encountered by either mechanical or electrical systems related to the control of a PMSM.

- Saturation treatment module design (saturation and antiwindup) — A good design of the motor control system requires prediction and management of boundaries of control linearity, in order to achieve performance targets. Saturation of control output can cause inefficient, suboptimum, or unstable operation, and must be managed carefully in order to avoid these problems.

  Saturation handling covered in this document describes the methods designed to detect saturation of the controller outputs, such as current, voltage, or speed, and the way in which the controllers must be modified or functionally enhanced to counteract unwanted effects.

- Recovery module design — Fault management in a motor control system needs to be designed assuming that faults will eventually occur. When this happens, one important decision is how they will be handled.

  Unfortunately, malfunctions frequently affect electromechanical systems, and in some cases the best response is for the motor to be brought to a stop. Fortunately there are system malfunctions that can be predicted and sometimes treated depending on the degree of severity, and whether sufficient input signals are available.

  There is a strong relationship between the recovery and monitoring system. The monitoring system provides the recovery system with information about detected faults. The recovery system is meant to bring the motor back to its previous operation, in the case of a motor stall or fault.

- Comparison of AN1292 and MC Application Framework — This document provides an analysis into differences between AN1292 software and the Motor Control Application Framework supplied with motorBench™ Development Suite. The intention here is to retrospectively review the improvements and limitations of the new Application Framework source code relative to the reference application note software from AN1292.