Flyback Converter Backup Power for Inverter Gate Drivers

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Solution Overview

Problem

Inverters for electric machines face challenges during power interruptions, where high-voltage capacitors maintain high voltage levels, leading to potential disconnection of alternating current leads and loss of power for gate driver controllers, resulting in electrical and inductive losses.

Innovation Solution

A vehicle power system with a controller programmed to discharge stored energy from a high-voltage capacitor using a flyback converter coupling, ensuring continued switching of the inverter to dissipate energy through the motor, thereby managing electrical and inductive losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the high-voltage capacitor maintains high voltage levels during power interruption, then the voltage potential across inverter switches is preserved, but electrical losses and inductive losses increase due to disconnected alternating current leads and gate driver power loss

Engineering Contradiction:

Improvevoltage potential maintenanceVSAvoidelectrical and inductive losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent converts the harmful stored energy in the high-voltage capacitor into a beneficial discharge process. By detecting power interruption conditions and actively controlling the switches to discharge the capacitor through the motor, the system transforms wasted energy into useful work, thereby reducing losses while maintaining voltage potential during the transition period.

Inventive Principle:

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

Solution Approach 2:

The patent ensures continuous operation of the inverter switches even during power interruption by providing backup power to the gate driver controller. This allows the switching action to continue uninterrupted, maintaining voltage potential across the capacitor while simultaneously discharging stored energy through controlled switching, thus eliminating the discontinuity that causes energy losses.

Inventive Principle:

Principle #20Continuity of useful action

2Reliability

If the gate driver controller loses power during interruption, then the controller can no longer actuate the gates, but the high-voltage capacitor continues to maintain high voltage levels causing energy losses

Engineering Contradiction:

Improvegate driver operationVSAvoidinductive losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements a backup power supply that activates before the gate driver controller completely loses power. This preliminary action ensures continuous gate actuation capability during the power interruption transition, allowing the system to maintain controlled switching and discharge the capacitor energy through the motor, preventing the controller failure that would otherwise cause inductive losses.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The backup power supply acts as an intermediary between the main power source and the gate driver controller during power interruption. It bridges the power gap, ensuring continuous operation of the gate driver while the main power is interrupted, thereby maintaining the ability to control switch actuation and manage energy discharge without controller failure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the alternating current lead becomes disconnected during interruption, then the motor connection is lost, but the high-voltage capacitor maintains voltage potential leading to electrical losses

Engineering Contradiction:

Improvevoltage potential maintenanceVSAvoidelectrical losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent converts the potentially harmful disconnected state into a beneficial discharge path by routing the capacitor energy through the motor windings via controlled switch actuation. Even though the normal AC lead connection is interrupted, the system creates an alternative discharge path that utilizes the stored energy productively, transforming electrical losses into useful magnetic field generation in the motor.

Inventive Principle:

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

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 solution effectively manages energy dissipation during power interruptions, reducing electrical and inductive losses by ensuring continuous operation of the inverter and maintaining system stability.

Implementation Method 1

a high-voltage capacitor of the inverter, that is electromagnetically coupled via a coupling to rails and a gate driver

Methodology Applied

Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Implementation Method 2

electrical losses associated with the switching dissipates the stored energy

Methodology Applied

Scientific EffectElectrical losses: Joule Heating

Implementation Method 3

inductive losses associated with the motor dissipates the stored energy

Methodology Applied

Scientific EffectInductive losses: Eddy Currents

Data Source

PatentUS10252618B2Backup electrical supply for main capacitor discharge

Publication Date: 2019.04.09 FORD GLOBAL TECH LLC

AI summary

A vehicle may include an electric drive system including switches having gates configured to control the switches. The vehicle may include a galvanic isolation coupling having a primary side electrically connected with an input power source and a secondary side electrically connected with a gate driver circuit. The gat driver circuit has a controller configured to actuate the gates and a power supply circuit electrically connected to the controller to provide backup power. The galvanic isolation coupling may be a flyback converter.