Motor Control Using Current-Based Copper Loss Estimation
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Solution Overview
Problem
Existing electric motor control devices require expensive temperature detectors to accurately calculate power consumption, increasing costs due to the need for additional components and design changes.
Innovation Solution
An electric motor control device that estimates the temperature of electric motors from detected current values, calculates the resistance value based on the estimated temperature, and uses this resistance value to calculate copper loss without the need for a temperature detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature detector is added to calculate correct resistance values, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The electric motor control device uses its own existing current detection section to detect current values, which are then used to calculate temperature and resistance values. The system serves itself by utilizing already-present components (current detector, calculator) to obtain temperature information without requiring external temperature detectors, thereby maintaining measurement precision while avoiding increased device complexity
Solution Approach 2:
The current detection section performs multiple functions: it detects current for motor control purposes and simultaneously provides current values that are used to calculate temperature and resistance for power loss computation. This multi-functionality eliminates the need for separate temperature detection hardware, resolving the contradiction between measurement precision and device complexity
2Measurement precision
If a temperature detector is added to calculate correct resistance values, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The system uses its own current detection capability to derive temperature and resistance information, eliminating the need to purchase and install separate temperature detector components. This self-service approach maintains accurate power consumption calculation while significantly reducing manufacturing costs by avoiding additional hardware purchases
Solution Approach 2:
The invention replaces expensive temperature detector hardware with a computational approach using existing current detection data. The 'cheap' solution uses software calculation (current-based temperature estimation) instead of expensive physical temperature sensing components, achieving the same measurement precision goal at lower manufacturing cost
3Measurement precision
If board design and mold changes are made to accommodate temperature detector, then measurement precision is improved, but ease of manufacture worsens
Solution Approach 1:
The invention extracts the temperature measurement function from the physical domain (temperature detectors, board design changes, mold modifications) and transfers it to the computational domain (current-based calculations). By taking out the need for physical temperature sensing hardware and its associated manufacturing complexities, the solution maintains measurement precision while dramatically simplifying manufacturing processes
Solution Approach 2:
The invention replaces the mechanical/physical temperature detection system (temperature detectors, board design, mold changes) with an electrical/computational system that uses current values to estimate temperature. This substitution eliminates the need for physical hardware modifications while achieving the same measurement precision, thereby improving ease of manufacture
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 approach allows for accurate calculation of power consumption at a lower cost, eliminating the need for temperature detectors and reducing design and manufacturing complexities.
Implementation Method 1
the resistance value used to calculate the copper loss changes with changes in temperature
Implementation Method 2
the resistance value used to calculate the copper loss changes with changes in temperature
Data Source
AI summary
A electric motor control device comprising a converter section converting AC voltage to DC voltage, an inverter section converting DC voltage from the converter section to AC voltage and supplying said AC voltage to electric motor, an inverter control unit controlling said inverter section, a current detection unit detecting the current flowing in said electric motors and a power calculation unit estimating the temperature of said electric motors from said detected current, calculating the resistance of said electric motors from said estimated temperature, and calculating the copper loss from said calculated resistance.