Brushless Linear Actuator Control for Electronic Braking

Solution Overview

Problem

Linear actuators using non-self-locking spindles require mechanical brakes to prevent uncontrolled rotation, which increase cost, space requirements, and are subject to mechanical wear and variable braking force due to factors like lubrication and temperature.

Innovation Solution

A brushless DC motor with a controller and driver circuit that adjusts the multiphase voltage signal to match or mismatch the back electromotive force, reducing efficiency to create a braking effect when excessive speed is detected, using detector circuitry to sense rotor speed and adjust the waveform frequency or amplitude.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical brakes are used to prevent uncontrolled rotation, then position control and safety are improved, but device complexity, cost, and space requirements increase

Engineering Contradiction:

Improveposition controlVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical braking systems with an electronic control system that uses the brushless DC motor's electromagnetic characteristics to provide braking effect. The controller adjusts the multiphase voltage signal to create a braking torque through electromagnetic interaction, eliminating the need for separate mechanical brake components while maintaining position control and safety.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The brushless DC motor is designed to perform multiple functions: it provides driving torque during normal operation and generates braking torque when needed by adjusting the voltage signal waveform. This multi-functionality integrates the braking capability into the motor itself, reducing the need for separate braking mechanisms and simplifying the overall device structure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If mechanical brakes are used to prevent uncontrolled rotation, then safety is improved, but manufacturing cost increases

Engineering Contradiction:

ImprovesafetyVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical braking systems with an electronic control system that uses the brushless DC motor's electromagnetic characteristics to provide braking effect. The controller adjusts the multiphase voltage signal to create a braking torque through electromagnetic interaction, eliminating the need for separate mechanical brake components while maintaining position control and safety.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Force

If mechanical brakes are used to prevent uncontrolled rotation, then braking effect is provided, but mechanical wear and variability increase due to lubrication and temperature factors

Engineering Contradiction:

Improvebraking forceVSAvoidbraking force stability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The patent replaces mechanical braking systems with an electronic control system that uses the brushless DC motor's electromagnetic characteristics to provide braking effect. The controller adjusts the multiphase voltage signal to create a braking torque through electromagnetic interaction, eliminating the need for separate mechanical brake components while maintaining position control and safety.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the electrical parameters (voltage signal waveform, frequency, and amplitude) to control the braking effect. By adjusting these electrical parameters, the braking torque can be precisely controlled without being affected by mechanical wear, lubrication conditions, or temperature variations that plague mechanical braking systems.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Provides a braking effect without mechanical brakes, reducing energy consumption and maintaining position control, while minimizing mechanical wear and variability.

Implementation Method 1

a brushless DC motor comprising a number of stator coils and a permanent magnet rotor, said brushless DC motor generating a back electromotive force when the permanent magnet rotor is turned around

Methodology Applied

Scientific EffectBack electromotive force: Electromagnetic Induction

Data Source

PatentEP3378154B1A linear actuator with a brushless DC motor

Publication Date: 2026.01.07 LINAK AS

Figure 1a~2
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AI summary

A linear actuator comprises a brushless DC motor (31), a driver circuit (51) for providing a multiphase voltage signal to the motor (31) and a controller (58) for detecting a rotor position and providing control signals to the driver circuit (51) in dependence thereof. Detector circuitry (61) detects a signal indicative of rotor speed. The controller (58) is configured to control the driver circuit (51) to drive the motor with a first waveform of the multiphase voltage signal, when the indicative signal indicates that the rotor speed does not exceed a predetermined speed; and control the driver circuit (51) to drive the motor with a second waveform of the multiphase voltage signal, when the indicative signal indicates that the rotor speed exceeds the predetermined speed, wherein the second waveform is selected to drive the motor (31) with an efficiency less than the efficiency when driven by the first waveform.