DC-Link Capacitor Discharge Using Controller Backup Power

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In electrified vehicles, the discharge of a link capacitor in the traction powertrain is not efficiently managed during shutdown events, leading to potential voltage imbalances and energy loss, as existing systems rely on an external power source that may be disrupted, preventing timely and controlled discharge.

Innovation Solution

A controller with an on-board power source, such as a super capacitor, is used to detect shutdown events and activate the inverter to discharge the link capacitor, ensuring timely and controlled discharge by applying a discharge pulse to the power switches, even when the external power source is disrupted.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an external power source is used to control the inverter during shutdown events, then the controller can operate the inverter, but the discharge of the link capacitor is delayed and unreliable when the external power source is disrupted

Engineering Contradiction:

Improvereliability of link capacitor dischargeVSAvoidtime delay in link capacitor discharge

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The controller uses its own on-board power source to power itself during the link capacitor discharge process, making the discharge operation self-sufficient and independent of external power sources. This ensures reliable and timely discharge even when external power is disrupted.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The controller pre-charges its on-board power source before shutdown events occur, so that when a shutdown event happens, the controller immediately has the power needed to operate the inverter and discharge the link capacitor without waiting for external power availability.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the controller uses on-board power source to operate during shutdown events, then the link capacitor can be discharged timely and reliably, but the controller requires additional power storage capacity

Engineering Contradiction:

Improvereliability of link capacitor dischargeVSAvoidcomplexity of controller power system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The controller powers itself during critical discharge operations using its own on-board power source, eliminating dependency on external power sources and ensuring reliable operation during shutdown events when external power may be disrupted.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The on-board power source serves dual purposes: it powers the controller during normal low-power operations and provides the necessary power for the inverter operation during link capacitor discharge events, reducing the need for separate power supply systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Loss of energy

If the link capacitor is not discharged efficiently during shutdown events, then the system components remain powered, but voltage imbalances and energy loss occur

Engineering Contradiction:

Improveenergy loss from link capacitorVSAvoidshutdown speed

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The controller maintains continuous operation of the inverter during the discharge process by powering itself from its on-board power source, ensuring the discharge action continues uninterrupted until the link capacitor is fully discharged, thereby preventing energy loss and voltage imbalances.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The controller monitors the discharge process and continues operating the inverter until the link capacitor voltage reaches the target threshold, ensuring complete discharge and preventing residual energy loss while maintaining system stability throughout the process.

Inventive Principle:

Principle #23Feedback

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

This solution enables reliable and efficient discharge of the link capacitor during shutdowns, maintaining system stability and preventing energy loss by utilizing the on-board power source to ensure the link capacitor is discharged within a specific time frame.

Implementation Method 1

The controller has an on-board power source (such as an on-board capacitor)

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

The inverter is configured to drive a motor with power from a battery via a link capacitor

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentUS12194876B2Controller-based active discharge circuitry for discharging link capacitor of traction powertrain of electrified vehicle

Publication Date: 2025.01.14 FORD GLOBAL TECH LLC

AI summary

A traction powertrain system of an electrified vehicle includes a power electronics module and a controller. The power electronics module, such as in the form of an inverter, is configured to drive a traction motor with power from a traction battery via a DC-link capacitor. The controller has an on-board power source, such as in the form of a super capacitor. The controller is configured to, in response to detecting an event in which the DC-link capacitor is to be discharged, use power from the on-board power source for controlling the power electronics module and control the power electronics module to operate in a manner causing the DC-link capacitor to be discharged.