Vehicle Motor Inverter Control for Speed Transient Power Stability

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Solution Overview

Problem

In electrical powered vehicles, sudden changes in rotational speed can lead to excessive charging or discharging of power storage devices due to delays in modifying input/output power command values caused by communication delays between control devices.

Innovation Solution

A system comprising a rotating electric machine, multiple power storage devices, a power conversion device, and two control devices, where the second control device detects sudden changes in rotational speed and adjusts input/output power command values independently to prevent excessive charging or discharging, using a speed detection unit and a power command generation unit to distribute power effectively among power storage devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If separate control devices are used for generating power commands and controlling power conversion, then functional specialization and modular design are improved, but communication delay causes excessive charging/discharging of power storage devices

Engineering Contradiction:

Improvecontrol device structureVSAvoidpower storage device operation

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The second control device preliminarily detects sudden changes in rotational speed directly from the rotating electric machine and proactively corrects power commands before excessive charging/discharging occurs. This preliminary detection and correction mechanism prevents the harmful effect of communication delay between separate control devices.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements a feedback mechanism where the second control device continuously monitors rotational speed and uses this feedback to dynamically adjust power commands. When sudden changes are detected, the feedback loop triggers immediate correction of power distribution to prevent excessive charging or discharging of power storage devices.

Inventive Principle:

Principle #23Feedback

2Speed

If rotational speed changes abruptly, then vehicle responsiveness is improved, but power distribution cannot be adjusted in time leading to excessive charging/discharging

Engineering Contradiction:

Improverotational speed change responseVSAvoidpower command adjustment time

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The second control device performs preliminary detection of sudden rotational speed changes and immediately prepares corrected power commands without waiting for communication from the first control device. This eliminates the time loss that would otherwise occur during inter-device communication and command adjustment.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The second control device independently detects rotational speed changes and self-corrects power commands without requiring external intervention or communication delays. This self-service capability ensures immediate response to speed changes while preventing excessive charging or discharging of power storage devices.

Inventive Principle:

Principle #25Self-service

3Device complexity

If power commands are transmitted through communication between control devices, then system modularity is improved, but transmission delay causes excessive charging/discharging of power storage devices

Engineering Contradiction:

Improvecontrol system architectureVSAvoidpower storage device charging/discharging control

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The second control device preliminarily detects sudden changes in rotational speed and proactively corrects power commands before excessive charging/discharging occurs. This preliminary detection and correction mechanism prevents the harmful effect of communication delay between separate control devices.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The second control device acts as an intermediary that directly monitors rotational speed and intermediates power command correction. By inserting this intermediary detection and correction function, the system compensates for the inherent delay in communication between the first control device and power conversion control, preventing excessive charging or discharging.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7953525B2Electrical powered vehicle incorporating motor and inverter, and control method therefor

Publication Date: 2011.05.31 TOYOTA JIDOSHA KK

AI summary

In an electrical powered vehicle including a control device for generating an input/output power command value for a power storage device and a control device for controlling a power conversion device and a rotating electric machine, provided separately, when there is a sudden change in the rotational speed of a rotating electric machine, the input/output power command value of a power storage device intrinsically set by an HV-ECU is corrected corresponding to the change in the rotational speed of the rotating electric machine by a control device MG-ECU detecting the rotational speed of the rotating electric machine, without having to wait for modification of the input/output power command value from the HV-ECU. Accordingly, there can be prevented excessive charging and excessive discharging of a power storage device induced by delay in modifying the input/output power command value caused by transmission delay between control devices when the rotational speed of the rotating electric machine suddenly changes.