Star Point Controller for Bidirectional Power Transfer in Electric Motors

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Solution Overview

Problem

Existing vehicle onboard electrical systems with multiphase electric motors face challenges in efficiently managing power distribution between subsystems, particularly when high power consumers are integrated, leading to the need for additional components like DC/DC converters and separate generators.

Innovation Solution

The integration of a star point controller with the inverter controller in the electric motor, allowing for the control of star point current and enabling bidirectional power transfer between onboard electrical subsystems, effectively acting as a step-up or step-down converter without the need for additional DC/DC converters, by utilizing a star point switch and a DC link capacitor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate DC/DC converters and generators are used for power transfer between onboard electrical subsystems, then power management capability is improved, but device complexity and component quantity increase

Engineering Contradiction:

Improvepower management capabilityVSAvoidcomponent quantity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the DC/DC converter functionality into the existing inverter controller by adding a star point controller that manages current flow through the star point connection. This integration eliminates the need for separate DC/DC converters and generators, as the inverter controller now handles both motor control and inter-subsystem power transfer functions, directly reducing component quantity while maintaining power management capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The inverter controller is enhanced to perform multiple functions: traditional motor control via the inverter and additional power transfer between onboard electrical subsystems via the star point controller. This multi-functionality allows a single device to replace what would traditionally require separate dedicated components, reducing overall system complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If additional DC/DC converters and generators are integrated into the onboard electrical system, then power transfer capability between subsystems is improved, but weight and installation space increase

Engineering Contradiction:

Improvepower transfer capabilityVSAvoidsystem weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent combines the power transfer functionality into the existing inverter controller structure, utilizing the star point connection and DC link capacitor that are already part of the motor control system. This merging approach eliminates the need for additional heavy components like separate DC/DC converters and generators, directly reducing system weight while maintaining bidirectional power transfer capability between the 14-volt and 12-volt subsystems

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If additional DC/DC converters are used for bidirectional power transfer, then power management flexibility is improved, but cost increases

Engineering Contradiction:

Improvepower management flexibilityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent integrates bidirectional power transfer functionality into the existing inverter controller by adding a star point controller module. This approach eliminates the need for expensive separate DC/DC converters, directly reducing manufacturing cost while maintaining the flexibility to transfer power bidirectionally between onboard electrical subsystems based on operational requirements

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9908430B2Vehicle having an electric machine and two onboard power subsystems

Publication Date: 2018.03.06 BAYERISCHE MOTOREN WERKE AG

AI summary

A vehicle with an N-phase electric motor, with a first onboard electrical subsystem and with a second onboard electrical subsystem, wherein the electric motor includes a rotor and a stator system, and the first onboard electrical subsystem includes an inverter. The stator system is associated with the inverter and the electric motor is operable with an inverter controller according to the principle of field-oriented control such that the stator system is embodied in a star circuit in which the star point can be connected to the second onboard electrical subsystem directly or via a star point switch. The inverter controller includes a current controller and a star point controller, wherein the current controller controls phase currents of the stator system and the star point controller controls a star point current.