Battery Heating Control via PWM Feedback

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Solution Overview

Problem

Existing methods for heating power battery packs lack accuracy in controlling the current in the heating circuit, relying on indirect control of Insulated Gate Bipolar Transistors (IGBTs) which limits the precision of heating current adjustment.

Innovation Solution

A method and device that acquire average current values over multiple cycles to calculate a required current output value, using Pulse Width Modulation (PWM) signals with pre-calibrated control parameters to maintain a preset current value within a threshold, enhancing control accuracy and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If IGBT internal resistance control method is used, then heating function is achieved, but current control accuracy is low

Engineering Contradiction:

Improvecurrent control accuracyVSAvoidcontrol method complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a closed-loop feedback control system where the actual current is continuously detected and compared with the target current. The controller adjusts the PWM duty cycle based on the current deviation to maintain accurate current control. This feedback mechanism directly addresses the low control accuracy of the traditional IGBT internal resistance method.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the indirect mechanical/electrical control method (controlling IGBT internal resistance) with a direct electronic control method using PWM signals. This substitution enables precise current control by directly modulating the switch device based on feedback, rather than relying on indirect resistance control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If instantaneous shorting method is used, then heating speed is high, but control precision is low

Engineering Contradiction:

Improveheating speedVSAvoidcurrent control accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent uses periodic PWM signals to control the switch device, replacing the instantaneous shorting method. The PWM duty cycle is dynamically adjusted based on feedback to maintain the desired current level, enabling both high heating speed (through frequent switching) and precise current control (through duty cycle modulation).

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The closed-loop feedback system continuously monitors the actual current and adjusts the PWM duty cycle accordingly. This allows the system to maintain high heating performance while achieving precise current control, resolving the contradiction between heating speed and control precision.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If indirect IGBT control is used, then device operation is simple, but heating current adjustment precision is low

Engineering Contradiction:

Improveheating current adjustment precisionVSAvoidcontrol operation simplicity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces the indirect control method (adjusting IGBT internal resistance) with direct PWM control of the switch device. This substitution improves current adjustment precision while maintaining operational simplicity, as the PWM duty cycle can be directly controlled by the microcontroller based on feedback.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameter from IGBT internal resistance to PWM duty cycle. This parameter change enables precise current adjustment through duty cycle modulation, while the automated feedback control maintains ease of operation by eliminating manual resistance adjustments.

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 approach allows for precise control of the heating current, ensuring rapid and safe battery heating with improved accuracy compared to indirect IGBT control methods.

Implementation Method 1

an internal resistance of the power battery generates heat when a large current generated by instantaneous shorting flows through the internal resistance, thereby heating the power battery

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

outputting a Pulse width Modulation (PWM) signal to a switch device of the heating circuit according to a pre-calibrated PWM control parameter corresponding to the current output value

Methodology Applied

Scientific EffectPulse Width Modulation:

Data Source

PatentUS11309598B2Heating control method and heating control device

Publication Date: 2022.04.19 CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

AI summary

The present disclosure provides a heating control method and a heating control device. The heating control method includes: acquiring an average current value in a heating circuit of a power battery pack; calculating a current output value required for nth cycle according to an average current value of the nth cycle, an average current value of (n−1)th cycle, an average current value of (n−2)th cycle, a preset current value, n is equal to or greater than 3; outputting a PWM signal to a switch device of the heating circuit according to a pre-calibrated PWM control parameter corresponding to the current output value so that a difference between an actual current value in the heating circuit and the preset current value is less than a preset threshold.