Motor Control Device Voltage Current Threshold Optimization

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Solution Overview

Problem

Existing motor control devices experience increased inverter losses at low output due to excessively small voltage values when motor power is below a specific threshold.

Innovation Solution

A motor control device that adjusts voltage and current values based on necessary power, setting voltage to a predetermined value and varying current when power is below a threshold, and setting current to a predetermined value and varying voltage when power exceeds the threshold, to optimize motor control and reduce inverter losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the voltage value is reduced to match low power requirements, then the motor can operate at low output, but the inverter loss increases excessively

Engineering Contradiction:

Improvemotor output powerVSAvoidinverter loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent changes the control parameter from variable voltage to fixed voltage with variable current. By maintaining voltage at a predetermined level and adjusting only the current value according to power requirements, the system avoids the inverter loss increase that occurs when voltage is reduced, while still enabling low power operation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent dynamically switches control strategies based on power threshold. When power is below the threshold, it uses fixed voltage with variable current control; when power exceeds the threshold, it uses variable voltage with fixed current control. This dynamic adaptation optimizes performance across different operating conditions.

Inventive Principle:

Principle #15Dynamics

2Loss of energy

If the voltage value is maintained at a high level for all power outputs, then inverter loss is reduced, but the motor cannot efficiently operate at low power outputs

Engineering Contradiction:

Improveinverter lossVSAvoidmotor output power

Core Design Contradiction:

Loss of energyVSPower

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies partial action by using fixed voltage control only for the partial range of low power outputs below the threshold. For higher power outputs, it switches to variable voltage control, thus applying the fixed voltage strategy only where it is most beneficial for reducing inverter loss.

Inventive Principle:

Principle #16Partial or excessive action

3Device complexity

If the control method is simplified to use only variable voltage control, then the control system is easier to implement, but inverter loss increases at low power outputs

Engineering Contradiction:

Improvecontrol system complexityVSAvoidinverter loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent segments the power output range into two zones: below threshold and above threshold. For the below-threshold zone, it applies fixed voltage with variable current control; for the above-threshold zone, it applies variable voltage with fixed current control. This segmentation allows optimization for each specific operating range.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #15Dynamics

4Adaptability or versatility

If the control method uses variable voltage for all power levels, then the motor can adapt to different power requirements, but inverter loss becomes excessive at low power outputs

Engineering Contradiction:

Improvemotor power adaptationVSAvoidinverter loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10727776B2Motor control device

Publication Date: 2020.07.28 NIDEC TOSOK CORP

AI summary

A control unit calculates necessary power necessary to drive a motor in accordance with a torque designation value and a rotational speed of a motor, sets a voltage value to a predetermined voltage value, changes a current value in accordance with the necessary power, and drive the motor in a case in which the calculated necessary power is less than a predetermined threshold value, and sets the current value to a predetermined current value, changes the voltage value in accordance with the necessary power, and drives the motor in a case in which the calculated necessary power is equal to or greater than the predetermined threshold value.