Motor Power Conversion Device Total Loss Calculation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor drive systems face challenges in accurately detecting and managing various losses, particularly iron loss and stray load loss, which can lead to motor overheating and damage, especially in high-speed operations, and current-based thermal protection methods are inadequate for effective overload protection.
Innovation Solution
A motor power conversion device that calculates total loss by integrating input and output power, including copper loss, iron loss, and machine loss, and uses this calculation to determine when the motor is overloaded, stopping operation to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If current-based thermal protection method is used, then device complexity is reduced, but measurement precision of motor losses is insufficient
Solution Approach 1:
The patent introduces a power conversion device as an intermediary component between the motor and control system. This device calculates total loss by integrating input and output power measurements, providing accurate loss detection without requiring direct temperature sensors in the motor. The intermediary performs complex calculations that would otherwise require sophisticated measurement systems.
Solution Approach 2:
The patent replaces physical temperature detectors (mechanical/thermal sensing system) with an electronic calculation system that determines motor temperature through power integration. By substituting direct thermal measurement with electrical power measurement and calculation, the system achieves higher precision loss detection while reducing device complexity.
2Productivity
If high-speed operation is implemented, then productivity is improved, but iron loss increases causing motor overheating
Solution Approach 1:
The patent implements a feedback mechanism where the calculated total loss (including iron loss) is continuously monitored and used to control motor operation. When iron loss exceeds safe thresholds during high-speed operation, the system provides feedback to reduce speed or adjust operation, preventing overheating while maximizing productivity during normal operation.
Solution Approach 2:
The patent makes the motor operating parameters dynamic by continuously calculating total loss based on real-time input and output power measurements. The system dynamically adjusts operation to account for varying iron loss at different speeds, enabling high-speed operation when conditions permit while preventing overheating when iron loss becomes excessive.
3Temperature
If dysprosium additive is used in permanent magnet, then heat resistance is improved, but moment of inertia is reduced affecting low-speed torque
Solution Approach 1:
The patent compensates for the reduced moment of inertia caused by dysprosium additives by dynamically adjusting operating parameters. The total loss calculation system monitors energy consumption and adjusts voltage, frequency, and current parameters to maintain adequate low-speed torque while preserving the heat resistance benefits of dysprosium-containing permanent magnets.
Data Source
Figure 1A~1B
Figure 2
Figure 3A
AI summary
Iron loss is one type of damage to a motor; when iron loss suddenly becomes large in the high-speed range of a motor, the motor cannot be protected by an electronic thermal relay for overload detection which operates at a fixed product of current squared and time calculated on the basis of current detection in the motor. This motor power conversion device accurately detects total loss, which includes copper loss, iron loss, mechanical loss, stray load loss, etc., without attaching a temperature detector on the motor winding, and provides overload detection protection to the motor. By calculating the total loss, which in addition to copper loss includes iron loss, quantitatively difficult-to-predict stray load loss and mechanical loss, as the total loss obtained by subtracting the output power from the input power of the motor, a motor power conversion device is realized with an overload protection electronic thermal relay which detects by constantly performing said calculation even with the motor in four-quadrant operation, including power running and regenerative operation, and operates at a fixed product of time and total loss.