Brushless Motor Controller PWM Hardware Commutation

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Solution Overview

Problem

Brushless motor controllers face performance issues due to interrupt clashes, which can delay the execution of interrupt service routines and affect motor power and efficiency when multiple interrupts occur simultaneously.

Innovation Solution

A controller design that uses PWM modules configured in half-bridge or full-bridge mode to generate control signals for commutating and freewheeling the motor winding, eliminating the need for software interrupts by using hardware peripherals to define commutation and freewheeling times, allowing for prompt updates based on motor speed and supply voltage changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If software interrupts are used to control winding commutation timing, then the controller can respond to motor events, but interrupt clashing occurs causing execution delays that adversely affect motor power and efficiency

Engineering Contradiction:

Improvemotor power and efficiencyVSAvoidinterrupt execution delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the software-based interrupt mechanism with a hardware-based PWM module that automatically generates commutation signals. The PWM module operates as a dedicated hardware peripheral that can generate timed interrupts and control signals without requiring processor intervention, thereby eliminating software interrupt clashes and execution delays.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The PWM module is configured to autonomously generate commutation signals and manage its own timing without requiring software interrupts. The module uses its internal timer and counter resources to automatically produce the required control signals for winding commutation, freeing the processor from interrupt service routines and eliminating the associated delays.

Inventive Principle:

Principle #25Self-service

2Speed

If the processor services interrupts immediately, then real-time control is achieved, but the processor cannot service other interrupts simultaneously causing execution delays

Engineering Contradiction:

Improveresponse speed to motor eventsVSAvoidprocessor throughput

Core Design Contradiction:

SpeedVSProductivity

Solution Approach 1:

The patent divides the control functions into separate hardware modules: the PWM module handles commutation signal generation and timing, while the processor handles higher-level control decisions. This segmentation allows the PWM module to operate independently at hardware speed for time-critical functions, while the processor maintains overall system control without being bottlenecked by interrupt service routines.

Inventive Principle:

Principle #1Segmentation

3Reliability

If hardware PWM modules are used to generate commutation signals, then interrupt clashing is avoided, but the device complexity increases

Engineering Contradiction:

Improvecontrol signal timing accuracyVSAvoidcontroller hardware complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent utilizes the PWM module's multiple functions to accomplish both commutation signal generation and timing control in a single hardware component. The PWM module can operate in different modes (full-bridge, half-bridge) and can generate various waveforms, providing multi-functional capability that reduces the need for additional dedicated hardware components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9431931B2Controller for a brushless motor

Publication Date: 2016.08.30 DYSON TECH LTD

AI summary

A controller for a brushless motor that includes a PWM module configured in half-bridge or full-bridge mode. The PWM module outputs control signals for controlling the excitation of a winding of the motor, and one of the duty cycle and the period of the PWM module defines a time at which the winding is commutated.