Power Converter Pre-Charge Using External Inductance

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Solution Overview

Problem

Power conversion circuitry in transport climate control systems experiences uncontrolled current peaks when coupling external AC or DC sources, potentially damaging diodes due to immediate voltage rise at the DC link, necessitating pre-charging of the DC link capacitor to prevent overcurrent conditions.

Innovation Solution

The power converter incorporates a pre-charge circuit, such as a boost converter, that uses an inductive component of the host vehicle or climate control unit to charge the DC link capacitor to a level equal to or greater than the peak external voltage, preventing immediate current flow through diodes and thus avoiding damage, with the pre-charge circuitry being internal to the power converter to accommodate various external sources without additional weight or cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pre-charge circuit is added to prevent uncontrolled current peaks, then diode damage is prevented and reliability is improved, but device complexity and cost increase

Engineering Contradiction:

Improvediode protection from overcurrentVSAvoidpre-charge circuit components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The inductive component is designed to serve dual purposes: its primary function in the host vehicle or climate control unit, and a secondary function as the inductor for the boost converter pre-charge circuit. This eliminates the need for a dedicated pre-charge inductor, reducing component count while maintaining diode protection functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the pre-charge circuit functionality with existing components by using the inductive component (motor or generator) as the boost converter inductor. This consolidation integrates the pre-charge function into the existing power conversion architecture without adding separate dedicated components.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If additional pre-charge components are added, then overcurrent protection is achieved, but weight and volume increase

Engineering Contradiction:

Improveovercurrent condition preventionVSAvoidpre-charge circuitry weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The inductive component serves multiple functions within the system - its primary function in the host vehicle or climate control unit, and simultaneously functions as the energy storage inductor for the boost converter pre-charge circuit. This multi-functionality eliminates the need for additional dedicated pre-charge components, thereby reducing overall system weight.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If a dedicated pre-charge inductor is added, then DC link capacitor charging is controlled, but manufacturing cost increases

Engineering Contradiction:

ImproveDC link voltage controlVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The inductive component is designed to perform its primary function while also serving as the boost converter inductor for pre-charging the DC link capacitor. This eliminates the need for a separate dedicated pre-charge inductor, reducing component count and manufacturing cost while maintaining controlled DC link voltage charging.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Device complexity

If the same inductive component is used for both host vehicle functions and pre-charge, then component count is reduced, but the inductive component must handle higher current stresses

Engineering Contradiction:

Improvenumber of componentsVSAvoidinductive component current handling

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The boost converter pre-charge circuit activates before the main power conversion operation begins. The inductive component is first used to charge the DC link capacitor to the required voltage level, preventing inrush current. After pre-charging is complete, the inductive component then resumes its primary function in the host vehicle or climate control unit. This sequential operation allows the component to handle elevated current stresses temporarily during pre-charge without requiring permanent oversizing.

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

This solution effectively prevents diode damage from overcurrent conditions, reduces the power converter's weight, cost, and space requirements, while improving reliability by minimizing the number of components and allowing the same pre-charge circuitry to be used for multiple external voltage sources.

Implementation Method 1

a pre-charge circuit configured to charge the DC link capacitor, wherein the pre-charge circuit comprises a boost converter comprising a switch and inductor coupling terminals configured to couple to an inductive component external to the power converter

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11876446B2Power converter

Publication Date: 2024.01.16 THERMO KING CORP

AI summary

The present disclosure relates to a power converter for use in a host vehicle. The power converter comprises a DC link, a DC link capacitor, and a pre-charge circuit configured to charge the DC link capacitor. The pre-charge circuit comprises a boost converter comprising a switch and inductor coupling terminals configured to couple to an inductive component external to the power converter.