Inverter Controller Active Short Circuit for Hybrid Vehicle Battery Protection

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Solution Overview

Problem

In hybrid electric vehicles, the inability to produce an active short circuit condition in the electric motor when the microprocessor is malfunctioning or without power can lead to overcharging of the high-voltage traction battery, necessitating an improved method and system for independent control of the inverter controller to prevent battery damage.

Innovation Solution

The system includes an inverter controller with both a processor and an electric circuit that can independently generate driver signals to produce an active short circuit condition in the electric motor, allowing the system to prevent overcharging by comparing the motor speed to a threshold and generating control signals even in the absence of processor control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the microprocessor is used to control the inverter switches to produce an active short circuit condition, then the control can be flexible and adaptive, but the system fails to produce the active short circuit condition when the microprocessor is malfunctioning or without power

Engineering Contradiction:

Improveactive short circuit condition productionVSAvoidinverter controller structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The inverter controller is segmented into two independent control paths: a microprocessor-based software control path and a hardware circuit control path. The hardware circuit includes a comparator that independently monitors motor speed and generates control signals for the inverter switches, separate from the microprocessor. This segmentation ensures that if the microprocessor fails, the hardware circuit can still produce the active short circuit condition to prevent battery overcharging.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the control parameter from purely software-based microprocessor control to a dual-path approach including hardware-based analog/digital circuit control. The hardware circuit uses voltage comparison (comparing motor speed signal to a threshold voltage) to generate control signals, representing a parameter change from digital software logic to analog/digital hybrid control, thereby improving reliability while maintaining functionality.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the system relies solely on processor control to generate active short circuit condition, then the control logic can be updated via software, but the system cannot prevent battery overcharging when the processor is not active

Engineering Contradiction:

Improvebattery overcharging preventionVSAvoidindependent control capability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The hardware circuit performs self-service by autonomously monitoring motor speed and generating control signals without requiring microprocessor intervention. The comparator circuit automatically compares the motor speed signal with a reference voltage and directly controls the inverter switches to produce the active short circuit condition when needed, enabling the system to protect itself against battery overcharging even when the microprocessor is inactive or malfunctioning.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The hardware circuit is designed as a backup control mechanism that is always ready to activate independently of the microprocessor state. This prior cushioning ensures that if the microprocessor fails or becomes inactive, the system still has the capability to prevent battery overcharging by producing the active short circuit condition through the hardware circuit alone.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If an active short circuit condition is produced only when the microprocessor is active, then the control system remains simple, but the traction battery can be damaged due to overcharging when the microprocessor is malfunctioning

Engineering Contradiction:

Improveinverter controller structureVSAvoidbattery damage from overcharging

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The hardware circuit acts as an intermediary control mechanism between the motor speed sensor and the inverter switches. This intermediary circuit independently processes the motor speed signal and generates control signals for the inverter switches, providing a backup control path that prevents battery overcharging without requiring complex additional components beyond the comparator and associated circuitry.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11462920B2Method and system for producing an active short circuit condition in an electric motor of a hybrid electric vehicle

Publication Date: 2022.10.04 LEAR CORP

AI summary

A system for producing an active short circuit in an electric motor of a hybrid electric vehicle having a traction battery includes an inverter to be provided in communication with the motor and battery, and an inverter controller to generate driver signals to operate inverter switches to produce three-phase AC for the motor or to produce DC for battery charging. In response to motor speed exceeding a threshold, the controller is configured to generate driver signals to operate the inverter switches to produce an active short circuit in the motor to prevent battery overcharging. A processor and electric circuit are each configured to independently generate an active short circuit control signal operative to effectuate generation of the driver signals, the active short circuit produced based on an active short circuit control signal from the electric circuit in an absence of an active short circuit control signal from the processor.