DC-DC Converter Power Limit Control for Battery Safety

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Solution Overview

Problem

Existing power systems in vehicles, which include a DC-DC voltage converter between large-capacity and small-capacity batteries, risk unstable power supply to electric motors and potential over-discharge of the battery pack if the DC-DC voltage converter excessively consumes power, especially when the battery state of charge is low.

Innovation Solution

A power control system that includes sensors for voltage, current, and temperature, coupled with a microprocessor to determine available power in the battery pack and adjust the input power limit of the DC-DC voltage converter, ensuring that the power provided to the DC-AC inverter does not exceed the available power, thereby preventing over-discharge and maintaining stable power supply.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the DC-DC voltage converter consumes more power from the battery pack, then the power conversion capability is improved, but the battery pack may be over-discharged and damaged

Engineering Contradiction:
Improvepower conversion capabilityVSAvoidbattery pack safety
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent implements dynamic adjustment of the input power limit for the DC-DC voltage converter based on real-time battery state of charge (SOC) levels. The microprocessor continuously monitors battery SOC and dynamically modifies the maximum power that can be drawn from the battery pack, ensuring the converter operates within safe limits while maximizing power conversion capability when conditions permit.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system employs feedback control by continuously monitoring the battery pack's state of charge through voltage and current sensors, and using this information to adjust the input power limit of the DC-DC converter. The microprocessor receives feedback on actual power consumption and battery status, then modifies the power limit accordingly to prevent over-discharge while maintaining optimal performance.

Inventive Principle:
Principle #23Feedback

2Power

If the DC-DC voltage converter draws excessive power from the battery pack, then the voltage conversion efficiency is improved, but the power supply stability to the electric motor deteriorates

Engineering Contradiction:
Improvevoltage conversion efficiencyVSAvoidpower supply stability
Core Design Contradiction:
PowerVSStability of the object's composition

Solution Approach 1:

The system dynamically adjusts the input power limit based on real-time monitoring of battery state of charge and actual power consumption. This dynamic control ensures that the DC-DC converter maintains optimal voltage conversion efficiency while preventing excessive power draw that would compromise the stability of power supply to the electric motor.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters of the DC-DC voltage converter by adjusting its input power limit based on battery SOC levels and actual power consumption patterns. This parameter adjustment allows the system to optimize voltage conversion efficiency at different operating conditions while maintaining stable power supply to the motor.

Inventive Principle:
Principle #35Parameter changes

3Power

If a fixed high power limit is set for the DC-DC voltage converter, then the power conversion capability is improved, but the risk of battery over-discharge increases

Engineering Contradiction:
Improvepower conversion capabilityVSAvoidover-discharge risk
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

Instead of using a fixed high power limit, the system implements a dynamic power limit that adjusts in real-time based on battery state of charge levels. When SOC is high, the power limit can be higher to maximize conversion capability; when SOC drops below threshold levels, the limit automatically reduces to prevent over-discharge, thus eliminating the need for a consistently high fixed limit.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system takes preliminary anti-action by establishing preventive power limits based on predicted battery state of charge trends. Before the battery reaches dangerous low SOC levels, the microprocessor proactively adjusts the input power limit to prevent over-discharge, rather than reacting after damage occurs.

Inventive Principle:
Principle #9Preliminary anti-action

Data Source

PatentEP3051677B1Power control system and method for controlling input power limit of DC-DC voltage converter
Publication Date: 2018.09.26 LG CHEM LTD
  • EP3051677B1 patent drawingFigure 1
  • EP3051677B1 patent drawingFigure 2
  • EP3051677B1 patent drawingFigure 3

AI summary

A power control system for adjusting an input power limit of a DC-DC voltage converter is provided. The system includes a microprocessor that determines an amount of output power being output by a battery pack, an amount of available power in the battery pack, and an amount of input power being input to the DC-DC voltage converter. The microprocessor determines an amount of power being provided to the DC-AC inverter based on the amount of output power being output by the battery pack and the amount of input power being input to the DC-DC voltage converter. The microprocessor decreases the input power limit of the DC-DC voltage converter if a sum of the amount of power being provided to the DC-AC inverter and the amount of input power being input to the DC-DC voltage converter is greater than the amount of available power in the battery pack.