Hybrid Powertrain Layout Without a Bidirectional DC/DC Converter

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Solution Overview

Problem

The high production costs of hybrid electric vehicle powertrains are attributed to the inclusion of a bidirectional DC/DC converter for charging and discharging the power battery, which is unnecessary in existing powertrain structures.

Innovation Solution

A new powertrain structure that connects the power battery to both the generator system and the electric drive system, allowing them to be reused for charging and discharging without a dedicated bidirectional DC/DC converter, and includes a bus capacitor to manage energy flow based on temperature and power conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a bidirectional DC/DC converter is included in the powertrain for charging and discharging the power battery, then the power battery can be charged and discharged, but the production costs of the powertrain increase

Engineering Contradiction:

Improvepower battery charging and discharging capabilityVSAvoidproduction cost of powertrain

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The generator system and electric drive system are designed to perform multiple functions: they not only generate and consume electrical energy for vehicle operation but also serve as charging and discharging circuits for the power battery. The generator system can charge the power battery when the vehicle is running, and the electric drive system can discharge the power battery to assist propulsion, eliminating the need for dedicated bidirectional DC/DC converters.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a bidirectional DC/DC converter is included in the powertrain for charging and discharging the power battery, then the power battery can be charged and discharged, but the device complexity increases

Engineering Contradiction:

Improvepower battery charging and discharging capabilityVSAvoidpowertrain structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If the generator system or electric drive system is reused for charging and discharging the power battery, then the production cost is reduced, but the temperature management becomes more complex

Engineering Contradiction:

Improveproduction cost of powertrainVSAvoidtemperature management system

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent converts the harmful effect of heat into a beneficial feature by using temperature-based mode switching. When the generator system or electric drive system becomes overheated during charging or discharging operations, the control device automatically switches to an alternative system that is cooler, thereby preventing thermal damage while maintaining the simplified powertrain structure without dedicated bidirectional DC/DC converters.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 structure reduces production costs by eliminating the need for a bidirectional DC/DC converter and enables efficient heat balance management through temperature-based mode switching, optimizing energy utilization.

Implementation Method 1

A first end and a second end of the generator system are respectively connected to two ends of the bus capacitor

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS20260005540A1Powertrain, controller, and hybrid electric vehicle

Publication Date: 2026.01.01 HUAWEI DIGITAL POWER TECH CO LTD

AI summary

A powertrain, a controller, and a hybrid electric vehicle are described, where the powertrain includes a generator system, an electric drive system, and a bus capacitor. The generator system includes three first bridge arms connected in parallel and a generator. Two ends of each first bridge arm are respectively connected to two ends of the bus capacitor. A bridge arm midpoint of each first bridge arm connects to a three-phase winding of the generator. The electric drive system includes three second bridge arms connected in parallel and a motor. Two ends of each second bridge arm respectively connect to the two ends of the bus capacitor. A bridge arm midpoint of each second bridge arm connects to a three-phase winding of the motor.