Open Phase Detection in E-Motor Powertrains

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Solution Overview

Problem

Conventional motor control systems for vehicles fail to effectively detect open phase conditions across multiple speeds, including low and zero speeds, leading to inadequate assessment of motor operation and potential dangerous torque responses.

Innovation Solution

A system comprising a control unit and a detection unit with a current detection module that measures and compares phase currents to reference values using digital logic, enabling detection of open phase conditions at various speeds and transferring the motor into a safe state when necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional motor control systems use inverter-based assessment with motor averages, then motor operating parameters can be assessed during normal operation, but open phase conditions cannot be detected at low speeds or when motors are at rest

Engineering Contradiction:

Improveopen phase detection capabilityVSAvoiddetection coverage across speed ranges

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system segments the detection approach by using different detection methods for different operating conditions: using inverter-based assessment for normal operation and digital logic-based detection for low-speed and zero-speed conditions. This allows reliable open phase detection across the entire speed range without relying solely on motor averages.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary detection mechanism (digital logic components comparing phase currents) that bridges the gap between conventional inverter-based assessment and the need for low-speed detection. This intermediary system enables open phase detection at speeds where conventional methods fail.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If conventional techniques rely on measuring motor output over time to generate motor averages, then motor operation can be assessed during normal running, but detection is not possible at zero speed or low speeds

Engineering Contradiction:

Improveopen phase detection accuracyVSAvoidmotor speed range for detection

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The system performs preliminary detection actions by continuously monitoring phase currents through digital logic components even at zero speed or low speeds, before the motor enters the speed range where conventional inverter-based assessment becomes effective. This ensures detection capability is maintained across all speed conditions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The detection system dynamically adapts its method based on motor speed: using digital logic-based phase current comparison at low speeds and transitioning to inverter-based motor average assessment at higher speeds. This dynamic approach maintains measurement precision across the entire speed range.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If digital logic components are used to compare phase currents to reference values, then open phase conditions can be detected at all speeds including zero speed, but the system complexity increases

Engineering Contradiction:

Improvedetection capability across all speedsVSAvoiddetection system structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The digital logic components serve multiple functions: they compare phase currents to reference values for open phase detection, operate across all speed ranges including zero speed, and integrate with the existing control unit. This multi-functionality reduces the need for separate dedicated detection systems for different speed ranges.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the open phase detection functionality with the existing control unit by implementing digital logic components within the control architecture. This integration combines detection and control functions, reducing overall system complexity compared to having separate dedicated detection hardware.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10879832B2Method for detection of e-motor open-phase problem in electrified powertrain

Publication Date: 2020.12.29 KARMA AUTOMOTIVE LLC

AI summary

Systems and configurations for open phase detection of a motor in a vehicle by a current detection module having a logic gate configuration. In one embodiment, a detection unit coupled to a control unit includes a current detection module configured to measure at least one current value of each phase of the multi-phase electric motor the vehicle. The current detection module compares current values of each phase to at least one reference value to determine an open phase condition. Current values are compared by digital logic components of the current detection module, and the control unit is configured to control operation of the motor in response to the open phase condition. An open phase condition is detected based on at least one phase current having a near zero level and an unchanged current component for one phase.