Motor Generator Unit Multiplexed Output DC-DC Converter Elimination

Solution Overview

Problem

Hybrid electric powertrains with conventional DC-DC converters are bulky, costly, and inefficient, as they require separate systems for high-voltage and low-voltage energy storage and conversion, complicating engine restart and torque assistance in engine autostop scenarios.

Innovation Solution

A vehicle electrical system that integrates a polyphase motor generator unit (MGU) with a polyphase full-bridge active rectifier/inverter and a semi-active auxiliary rectifier, eliminating the need for a conventional DC-DC converter by using a controller to switch between high-voltage and low-voltage energy storage systems via solid-state switches, allowing the MGU to operate as both a motor and generator for efficient engine restart and torque assistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a conventional DC-DC converter is used to reduce high-voltage battery output to auxiliary voltage levels, then voltage conversion is achieved, but system mass, cost, and packaging size increase

Engineering Contradiction:

Improvevoltage conversion capabilityVSAvoidsystem mass

Core Design Contradiction:

PowerVSWeight of stationary object

Solution Approach 1:

The patent combines the DC-DC converter functionality with the alternator by integrating the converter circuitry into the alternator housing and using the alternator's stator windings to provide both alternator output and DC-DC conversion output, thereby eliminating the need for a separate DC-DC converter unit and reducing overall system mass

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The alternator is designed to perform multiple functions: generating auxiliary voltage during engine operation, providing engine restart capability through integrated starter motor functionality, and performing DC-DC voltage conversion to charge the auxiliary battery, thereby eliminating the need for separate dedicated components for each function

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Power

If a conventional DC-DC converter is used for voltage reduction, then voltage conversion is achieved, but system cost increases

Engineering Contradiction:

Improvevoltage conversion capabilityVSAvoidsystem cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent combines the DC-DC converter functionality with the alternator by integrating the converter circuitry into the alternator housing and using the alternator's stator windings to provide both alternator output and DC-DC conversion output, thereby eliminating the need for a separate DC-DC converter unit and reducing overall system mass

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The alternator is designed to perform multiple functions: generating auxiliary voltage during engine operation, providing engine restart capability through integrated starter motor functionality, and performing DC-DC voltage conversion to charge the auxiliary battery, thereby eliminating the need for separate dedicated components for each function

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Power

If a conventional DC-DC converter is used for voltage reduction, then voltage conversion is achieved, but packaging size increases

Engineering Contradiction:

Improvevoltage conversion capabilityVSAvoidpackaging size

Core Design Contradiction:

PowerVSArea of stationary object

Solution Approach 1:

The patent combines the DC-DC converter functionality with the alternator by integrating the converter circuitry into the alternator housing and using the alternator's stator windings to provide both alternator output and DC-DC conversion output, thereby eliminating the need for a separate DC-DC converter unit and reducing overall system mass

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The alternator is designed to perform multiple functions: generating auxiliary voltage during engine operation, providing engine restart capability through integrated starter motor functionality, and performing DC-DC voltage conversion to charge the auxiliary battery, thereby eliminating the need for separate dedicated components for each function

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Power

If separate high-voltage and low-voltage energy storage systems are used, then voltage levels are maintained, but system complexity increases

Engineering Contradiction:

Improvevoltage level maintenanceVSAvoidsystem complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent combines the DC-DC converter functionality with the alternator by integrating the converter circuitry into the alternator housing and using the alternator's stator windings to provide both alternator output and DC-DC conversion output, thereby eliminating the need for a separate DC-DC converter unit and reducing overall system mass

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The control system continuously monitors the state of charge of the auxiliary battery and the output of the alternator, dynamically adjusting the DC-DC conversion process to optimize charging current and voltage, and coordinating with the engine control system to manage power flow between the high-voltage and low-voltage systems efficiently

Inventive Principle:

Principle #23Feedback

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 configuration reduces system mass, cost, and packaging size while enabling rapid engine restart and torque assistance by directly controlling the MGU as a motor or generator, optimizing energy flow and eliminating the need for a separate DC-DC converter, thus enhancing fuel efficiency and reducing operational complexity.

Implementation Method 1

Motor torque from the MGU cranks and starts the engine during an engine autostart event

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

Motor torque from the MGU in some BAS systems may also be used to selectively assist output torque from the engine in an electrical assist mode

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS9216707B2Motor generator unit with multiplexed output

Publication Date: 2015.12.22 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A vehicle includes an engine, a transmission connected to the engine, an auxiliary electrical load, and an electrical system. The electrical system includes a high-voltage energy storage system (HV-ESS), an auxiliary/low-voltage energy storage system (LV-ESS) connected to the load, a full-bridge active rectifier/inverter, a semi-active auxiliary rectifier, and a motor generator unit (MGU) connected to the HV-ESS via the active rectifier/inverter, and to the LV-ESS via the semi-active auxiliary rectifier. A controller establishes a first operating mode in which the MGU is operated as a motor for restarting or assisting the engine via the active rectifier/inverter, and second operating mode in which the MGU operates as a generator and the semi-active rectifier provides an auxiliary DC output voltage to the LV-ESS and the load. Another vehicle has first and second switches in lieu of the semi-active rectifier, with the active rectifier connected to the HV-ESS and LV-ESS via different switches.