Active Gate Driver Feedback Reduces Motor Ringing

Solution Overview

Problem

Brushless DC (BLDC) motors face inefficiencies due to resonant circuits caused by harmonics in pulsed waveforms, leading to electromagnetic interference and compliance issues with Electromagnetic Compatibility (EMC) regulations, which existing solutions like increased metal shielding cannot effectively address without increasing weight and cost.

Innovation Solution

An electric motor control system using a digital pre-distorter to generate pre-distorted signals for motor windings based on feedback signals, incorporating a Finite Impulse Response (FIR) filter and adaptive algorithms to optimize switching characteristics and reduce ringing, thereby improving EMC compliance without increasing weight or cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If metal shielding is increased to reduce electromagnetic interference, then EMC compliance is improved, but weight and cost increase

Engineering Contradiction:

Improveelectromagnetic interferenceVSAvoidmotor assembly weight

Core Design Contradiction:

Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

The patent converts the harmful ringing effect into a useful signal by using it as feedback. The resonant circuit's ringing is captured and fed back through an attenuator to a variable resistance element, where it modulates the damping characteristic. This transforms the previously harmful oscillation into a beneficial damping mechanism that actively suppresses electromagnetic interference without requiring additional shielding.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent dynamically changes the resistance parameter of the variable resistance element based on the feedback signal. The resistance value is modulated by the ringing signal itself, creating a time-varying damping characteristic that adapts to the resonant conditions. This parameter change allows the system to suppress ringing and electromagnetic interference without adding physical shielding mass.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If metal shielding is increased to reduce electromagnetic interference, then EMC compliance is improved, but cost increases

Engineering Contradiction:

Improveelectromagnetic interferenceVSAvoidmanufacturing cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent converts the harmful ringing effect into a useful signal by using it as feedback. The resonant circuit's ringing is captured and fed back through an attenuator to a variable resistance element, where it modulates the damping characteristic. This transforms the previously harmful oscillation into a beneficial damping mechanism that actively suppresses electromagnetic interference without requiring additional shielding.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent dynamically changes the resistance parameter of the variable resistance element based on the feedback signal. The resistance value is modulated by the ringing signal itself, creating a time-varying damping characteristic that adapts to the resonant conditions. This parameter change allows the system to suppress ringing and electromagnetic interference without adding physical shielding mass.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If sharp pulsed waveforms are used to drive coils for maximum efficiency, then motor efficiency is improved, but ringing and electromagnetic interference increase

Engineering Contradiction:

Improvemotor efficiencyVSAvoidringing and electromagnetic interference

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the output ringing signal is captured by a feedback network and fed back to the input through an attenuator. This closed-loop feedback allows the system to sense the ringing condition and automatically adjust the damping characteristic via the variable resistance element to suppress the ringing while maintaining the sharp pulse waveform for efficiency.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies preliminary damping action by using the feedback signal to pre-adjust the variable resistance element before the ringing reaches peak amplitude. This preliminary adjustment of the damping characteristic prevents the ringing from developing fully, thereby suppressing electromagnetic interference while maintaining motor efficiency.

Inventive Principle:

Principle #10Preliminary action

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

The system effectively reduces ringing and electromagnetic interference, enhancing the efficiency and EMC compliance of BLDC motors by iteratively adapting filter coefficients to match input signals with feedback, allowing for real-time optimization and compliance with regulations.

Implementation Method 1

incorporating a Finite Impulse Response (FIR) filter and adaptive algorithms to optimize switching characteristics and reduce ringing

Methodology Applied

Scientific EffectFinite Impulse Response (FIR) filter: Filter (electronic)

Implementation Method 2

a digital pre-distorter configured to generate the pre-distorted signal based on an input signal and a plurality of coefficients wherein the plurality of coefficients are based on a feedback signal that represents the current flow in the motor winding

Methodology Applied

Scientific EffectFeedback: Feedback

Data Source

PatentUS11258383B2Active gate driver with feedback

Publication Date: 2022.02.22 KK TOSHIBA

AI summary

An electric motor control system comprising an electronic switch configured to control a current flow in a motor winding based on a pre-distorted signal and a digital pre-distorter configured to generate the pre-distorted signal based on an input signal and a plurality of coefficients, wherein the plurality of coefficients are based on a feedback signal that represents the current flow in the motor winding.