Self-Heating Battery Control via Zero-Torque Current Pulses

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Solution Overview

Problem

Electric vehicle batteries face challenges in charging and performance in cold environments due to low temperatures, which can lead to inefficient charging and potential damage from lithium plating.

Innovation Solution

A control method for the inverter/motor drive unit generates alternating current pulse currents within the battery pack to self-heat the cells through internal resistance, maintaining zero torque to prevent motor engagement and damage, ensuring the battery is warmed before charging or use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the battery is operated in cold environments, then the vehicle can function in low temperatures, but charging efficiency deteriorates and lithium plating occurs

Engineering Contradiction:

Improvebattery operation in cold environmentsVSAvoidcharging efficiency and battery safety

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs preliminary heating of the battery using resistive heating elements before charging operations begin. Temperature sensors detect when battery temperature falls below a threshold, triggering the heating elements to warm the battery to an acceptable temperature range, preventing lithium plating and ensuring safe charging conditions are established in advance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Resistive heating elements serve as an intermediary mechanism between the power management system and the battery. These heating elements convert electrical energy to thermal energy, acting as a mediator that transfers heat to the battery without direct contact, enabling temperature control while isolating the battery from direct electrical heating sources

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If heating elements are added to warm the battery, then battery temperature increases, but device complexity increases

Engineering Contradiction:

Improvebattery temperatureVSAvoidsystem complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The power management system performs multiple functions: it manages normal charging/discharging operations, monitors battery temperature through sensors, and activates heating elements when needed. By integrating temperature control functionality into the existing power management architecture, the system achieves multi-functionality without adding separate dedicated heating control systems

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The heating control circuitry is merged with the existing power management integrated circuit (PMIC). The same control logic and power management infrastructure that handles charging is also used to control the heating elements, combining multiple functions into a single integrated system rather than using separate independent systems

Inventive Principle:

Principle #5Merging (Combining)

3Loss of energy

If pulse currents are used to heat the battery, then heating efficiency improves, but motor torque control becomes complex

Engineering Contradiction:

Improveheating efficiencyVSAvoidcontrol complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The system applies periodic pulse currents to the motor windings to generate heat in the battery. By switching current pulses on and off at controlled intervals, the system creates resistive heating in the battery while maintaining average current levels that produce minimal motor torque. This periodic action enables efficient heating while keeping the motor essentially stationary

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The control system dynamically adjusts pulse current parameters including amplitude, duration, and frequency to optimize heating efficiency while maintaining zero torque. By changing these electrical parameters, the system can deliver high peak currents for effective heating while ensuring the net mechanical output remains zero, preventing unwanted motor movement

Inventive Principle:

Principle #35Parameter changes

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 method efficiently heats the battery, maintaining power efficiency and preventing lithium plating, thus ensuring safe and effective charging and operation in cold conditions.

Implementation Method 1

control circuitry that provides one or more first current pulses to the motor using power from the battery to cause one or more second current pulses in the battery that heat the battery to a desired temperature

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11290045B2Devices, systems, and methods for self-heating batteries

Publication Date: 2022.03.29 NIO TECH ANHUI CO LTD

AI summary

At least one embodiment is directed to a system including a motor, a battery that provides power to the motor, and control circuitry that provides one or more first current pulses to the motor using power from the battery to cause one or more second current pulses in the battery that heat the battery to a desired temperature while maintaining zero torque in the motor.