Motor Power Conversion Control Under Storage Output Limits

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Solution Overview

Problem

Existing power conversion systems restrict the output of storage devices, limiting the maximization of motor characteristics, necessitating a solution to enhance motor performance even under restricted conditions.

Innovation Solution

A power conversion system that includes a power conversion device with a control unit to calculate powered drive energy, a current detection unit, and a computing circuit to adjust voltage commands based on motor encoder information and current values, temporarily improving motor characteristics by managing energy storage and supply.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the output of the storage device is restricted by control command values, then energy storage stability is improved, but motor characteristics cannot be maximally exerted

Engineering Contradiction:
Improveenergy storage stabilityVSAvoidmotor characteristics
Core Design Contradiction:
Stability of the object's compositionVSPower

Solution Approach 1:

The system dynamically adjusts the voltage command value based on real-time monitoring of motor operation state and energy storage level. When the motor operates in a restricted state and energy storage is sufficient, the control unit temporarily increases the voltage command value to improve motor characteristics. This dynamic adjustment resolves the contradiction by making the restriction flexible rather than fixed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control unit changes the voltage command parameter based on the determined operation state and energy storage level. By varying this key parameter, the system can temporarily enhance motor performance when conditions permit, while maintaining stability under normal operating conditions. This parameter change approach allows the system to adapt between stability and performance requirements.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If control command values are used to restrict storage device output, then device complexity is reduced, but motor performance optimization is limited

Engineering Contradiction:
Improvecontrol system simplicityVSAvoidmotor performance
Core Design Contradiction:
Device complexityVSPower

Solution Approach 1:

The control unit continuously monitors the motor operation state and energy storage level, using this feedback information to determine whether to adjust the voltage command value. This feedback mechanism enables performance optimization without requiring complex control logic, as the adjustment decisions are based on straightforward conditional evaluation of monitored parameters.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control unit automatically adjusts the voltage command value based on the determined operation state and energy storage level without requiring external intervention. This self-service capability allows the system to optimize motor performance autonomously while maintaining simple control architecture, as the control unit handles all decision-making internally.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4089910B1Power conversion system and motor control method based on same
Publication Date: 2026.01.28 HITACHI IND EQUIP SYST CO LTD
  • EP4089910B1 patent drawingFigure 1
  • EP4089910B1 patent drawingFigure 2
  • EP4089910B1 patent drawingFigure 3~4

AI summary

A power conversion system 200 includes a power conversion device 2 configured to supply electric power to a motor 3 and a power supply device 1 configured to supply electric power to the power conversion device 2. The power conversion device 2 includes a reverse converter 7 configured to convert the electric power, a control circuit 8 configured to control the reverse converter 7, and a current detector configured to detect a current flowing through the reverse converter 7. The power supply device 1 includes a storage device 6 configured to store electric power in accordance with a voltage, a step-up/down power supply circuit 5 configured to change the voltage of the storage device 6 based on a voltage command, and a voltage command computing circuit 15 configured to compute the energy stored in the storage device 6 and output it as the voltage command to the step-up/down power supply circuit 5. The control circuit 8 calculates powered drive energy of the motor 3 by using information from the motor 3 and a current value detected by the current detector. The voltage command computing circuit 15 computes the energy stored in the storage device 6 based on the powered drive energy calculated by the control circuit 8. When it is determined that the characteristics of the motor 3 are restricted, the voltage command computing circuit 15 temporarily changes the voltage command to improve the motor characteristics.