Electric Vehicle Control Device for Power Shortage Prevention

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Solution Overview

Problem

Fuel cell range extender electric vehicles face power shortages when the secondary battery's state of charge decreases, especially during high drive torque conditions like overloading and continuous uphill travel, due to the limited capacity of the fuel cell and the need for a balance between fuel cell size and battery charging.

Innovation Solution

A control device that adjusts the drive motor's output by setting a target value based on a request command and using electric power from both the secondary battery and fuel cell, with a fuel cell controller activating the fuel cell when the battery's capacity is low, and a control output setter reducing the motor's maximum output to prevent power shortages by prioritizing battery charging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the fuel cell capacity is increased to prevent power shortages during high drive torque conditions, then the power generating capacity is improved, but the device complexity and cost increase

Engineering Contradiction:

Improvepower generating capacityVSAvoidfuel cell capacity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent implements dynamic control of the drive motor's maximum output based on real-time battery state of charge levels. When SOC is high, the motor can operate at full power. When SOC drops below thresholds, the maximum output is reduced to prevent power shortages, eliminating the need for oversized fuel cells while maintaining reliability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the operating parameters of the drive motor by adjusting the maximum output limit according to battery charge levels. This dynamic parameter adjustment allows the use of smaller fuel cells while preventing power shortages through controlled output reduction when battery capacity is low

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the fuel cell capacity is increased to enable traveling with only the fuel cell, then the reliability is improved, but the advantages of the range extender configuration are impaired

Engineering Contradiction:

Improvetraveling capabilityVSAvoidrange extender advantage

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system dynamically adjusts the drive motor's maximum output based on real-time battery state of charge, enabling the vehicle to adapt to different operating conditions. This maintains reliability across varying scenarios while preserving the lightweight, flexible advantages of the range extender configuration

Inventive Principle:

Principle #15Dynamics

3Reliability

If the drive motor output is reduced to prevent power shortages, then the reliability is improved, but the productivity decreases

Engineering Contradiction:

Improvepower shortage preventionVSAvoidvehicle output

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system takes preliminary action by reducing the maximum output before power shortages occur. By monitoring battery state of charge and proactively limiting motor output when SOC drops below thresholds, the system prevents power shortages while minimizing impact on productivity through timely, controlled adjustments

Inventive Principle:

Principle #9Preliminary anti-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 power shortages by reducing the drive motor's output when the battery's capacity is low, ensuring the vehicle can continue operating without interruption and maintaining the advantages of a range extender by optimizing fuel cell and battery power usage.

Implementation Method 1

a fuel cell that is configured to generate the electric power to be supplied to the drive motor and the secondary battery

Methodology Applied

Scientific EffectFuel cell electrochemical reaction: Fuel Cell

Implementation Method 2

a secondary battery that is configured to supply an electric power to the drive motor

Methodology Applied

Scientific EffectBattery electrochemical reaction: Battery (electricity)

Data Source

PatentUS11007893B2Control device for electric vehicle and electric vehicle

Publication Date: 2021.05.18 SUBARU CORP

AI summary

A control device for an electric vehicle equipped with a drive motor and a fuel cell includes a control output setter, a motor controller, and a fuel cell controller. The control output setter is configured to set a target value of an output of the drive motor based on a request command value. The motor controller is configured to control an output of the drive motor based on the target value using an electric power from a secondary battery as a power source. The fuel cell controller is configured to control the supply of a generated power by activating the fuel cell when the remaining capacity of the secondary battery decreases or an output of the secondary battery is insufficient. The control output setter decreases an allowable maximum value of the output of the drive motor when the remaining capacity can be decreased even after the fuel cell is activated.