Motor Coil Battery Heating During Charging Without Torque Output

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Solution Overview

Problem

Existing electric vehicle battery heating systems incur high costs and prolonged charging times due to the inefficiency of heating processes when using PTC heaters, which cannot heat during charging at low temperatures.

Innovation Solution

An energy conversion device utilizing a reversible PWM rectifier and motor coil with multiple winding units to generate heat through controlled current flow, ensuring a vector sum of current vectors is zero to avoid torque output and heat the cooling liquid, thereby omitting additional heating devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If PTC heater or electric heating wire heater is used to heat the battery at low temperature, then the battery can be heated to a predetermined temperature, but the charging time becomes excessively long because heating and charging cannot be performed simultaneously

Engineering Contradiction:
Improvebattery temperatureVSAvoidcharging time
Core Design Contradiction:
TemperatureVSLoss of time

Solution Approach 1:

The patent merges the heating function and charging function into a single integrated process by using the motor coil as both a motor component and a heating element. During low-temperature charging, the reversible PWM rectifier converts AC power to DC power while the motor coil generates heat through controlled current flow, enabling simultaneous heating and charging operations that resolve the time loss issue

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The motor coil is designed to serve multiple functions: it acts as a motor coil during normal motor operation and as a heating element during low-temperature charging. This multi-functionality eliminates the need for separate heating devices and allows the same component to perform both propulsion and heating tasks, thereby reducing system complexity and improving charging efficiency

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Power

If additional power battery heating devices are added to improve heating efficiency, then the heating power and speed increase, but the device complexity and costs increase

Engineering Contradiction:
Improveheating powerVSAvoidheating system complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The motor coil is designed to serve multiple functions: it acts as a motor coil during normal motor operation and as a heating element during low-temperature charging. This multi-functionality eliminates the need for separate heating devices and allows the same component to perform both propulsion and heating tasks, thereby reducing system complexity and improving charging efficiency

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The motor coil generates heat for the battery using its own structure and the current already flowing through it during charging operations. The reversible PWM rectifier controls the current to produce heat in the motor coil, which then transfers heat to the cooling liquid and subsequently to the battery. This self-service approach avoids the need for external heating devices and reduces overall system complexity

Inventive Principle:
Principle #25Self-service

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 approach reduces costs and shortens charging times by efficiently heating the battery through the motor coil, enhancing heating power and speed while extending the service life of components.

Implementation Method 1

the external power supply, the reversible PWM rectifier, and the winding units in the motor coil form at least two sets of heating circuits. The reversible PWM rectifier is controlled, to cause a current outputted from the external power supply to flow through at least two sets of winding units of the motor coil to generate heat

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4043254B1Energy conversion device and vehicle
Publication Date: 2025.11.05 BYD CO LTD
  • EP4043254B1 patent drawingFigure 1~2
  • EP4043254B1 patent drawingFigure 3~4
  • EP4043254B1 patent drawingFigure 5~6

AI summary

An energy conversion device is provided. The energy conversion device includes a reversible pulse-width modulation (PWM) rectifier (102) and a motor coil (103). The motor coil (103) includes L sets of winding units, and each set of windings is connected with the reversible PWM rectifier (102), where L≥2 and is a positive integer. At least two sets of heating circuits of a to-be-heated device are formed by an external power supply (100), the reversible PWM rectifier (102), and the winding units in the motor coil (103). The energy conversion device controls the reversible PWM rectifier (102) according to a control signal, so that a current outputted from the external power supply (100) flows through at least two sets of winding units in the motor coil (103) to generate heat, and a vector sum of resultant current vectors of the at least two sets of the winding units on a quadrature axis of a synchronous rotating reference frame based on rotor field orientation of the motor is zero.