Motor Power Control for Low Battery State

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Solution Overview

Problem

Vehicles face challenges in maintaining smooth travel when the battery state of charge is low, as existing methods for reducing motor power consumption can lead to deterioration of engine or drive motor functions and potential shutdown due to inadequate power management.

Innovation Solution

A method and system that uses a controller to determine the state of charge of the battery and adjust power supply to motors using PWM, prioritizing power reduction based on current consumption and motor ratings to minimize battery discharge while maintaining essential vehicle functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If motor power consumption is reduced by stopping or reducing motor operation when battery state of charge is low, then battery consumption is reduced, but vehicle functions (cooling of engine and power electric parts) are deteriorated

Engineering Contradiction:

Improvebattery consumptionVSAvoidvehicle function

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The system segments the motor control into multiple levels: normal operation mode and power-saving mode. When battery state of charge drops below a threshold, the controller selectively reduces power to specific motors while maintaining critical functions. This segmentation allows differential treatment of motors based on their current consumption and functional importance, resolving the contradiction by reducing overall battery consumption while preserving essential vehicle functions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes operational parameters dynamically based on battery state of charge. When power saving is needed, the controller adjusts motor operating parameters (power levels, duty cycles) rather than completely stopping motors. This parameter adjustment reduces battery consumption while maintaining sufficient power for critical cooling functions, thus resolving the contradiction between energy conservation and function reliability.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If motor operation is completely stopped to maximize battery conservation, then battery discharge is minimized, but engine and drive motor cooling functions are compromised leading to potential damage

Engineering Contradiction:

Improvebattery dischargeVSAvoidengine damage

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The system takes preliminary action by monitoring battery state of charge and preemptively adjusting motor power distribution before complete battery depletion occurs. When state of charge drops below a threshold, the controller proactively reduces power to non-critical motors while maintaining power to motors essential for cooling. This preliminary anti-action prevents the harmful scenario of engine overheating while still achieving battery conservation, resolving the contradiction between minimizing battery discharge and preventing engine damage.

Inventive Principle:

Principle #9Preliminary anti-action

3Loss of energy

If power is reduced to motors with lower current consumption first, then battery consumption is reduced, but essential cooling functions may be compromised

Engineering Contradiction:

Improvebattery consumptionVSAvoidcooling function

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

The system implements feedback control by continuously monitoring both battery state of charge and motor operating conditions. The controller uses this feedback to dynamically adjust power distribution, ensuring that motors critical for cooling (even if they have lower current consumption) maintain sufficient power while non-critical motors receive reduced power. This feedback mechanism resolves the contradiction by preventing temperature-related issues while still achieving battery conservation through selective power reduction.

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

Effectively reduces battery consumption, preventing shutdown and engine damage by optimizing power distribution to motors, ensuring smooth vehicle operation even with low battery state of charge.

Implementation Method 1

An electric power may be supplied to each of the motors by applying a driving voltage by a PWM method in which a duty is adjusted.

Methodology Applied

Scientific EffectPWM (Pulse Width Modulation):

Data Source

PatentUS10189369B2Method and system for controlling motors

Publication Date: 2019.01.29 HYUNDAI MOTOR CO LTD

AI summary

A method and a system for controlling motors is provided to have a vehicle travel smoothly in such a manner that, when a state of charge of a battery for supplying electric power stored to a plurality of motors included in the vehicle is low, a consumption of the battery is reduced by decreasing the electric power supplied to each motor of the plurality of motors. The method of controlling motors includes: determining a state of charge of a battery storing electric power supplied to each motor of a plurality of motors; calculating a present current consumption of each motor of the plurality of motors when the state of charge of the battery is equal to or less than a predetermined reference value; and resetting a power supply to each motor of the plurality of motors, based on the present current consumption of each motor of the plurality of motors.