Driving device, compressor, and air conditioner
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Solution Overview
Problem
Conventional driving devices for rare earth magnet motors set an overly conservative overcurrent protection level to prevent demagnetization, limiting motor performance at low temperatures and reducing reliability due to frequent interruptions at temperature changes.
Innovation Solution
A driving device with an inverter for field weakening control, a current detector, a protection level setting unit, and a control device that adjusts the overcurrent protection level based on temperature, reducing the motor drive current when necessary to prevent demagnetization and maintain performance across the operating temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overcurrent protection level is set to prevent irreversible demagnetization at the highest temperature, then the motor is protected from demagnetization, but the motor cannot supply high current at low temperatures and its performance cannot be fully utilized
Solution Approach 1:
The overcurrent protection level is changed from a fixed value to a dynamically adjustable value based on motor temperature. The control device adjusts the protection level according to detected temperature, allowing high current at low temperatures for full performance and lower current at high temperatures to prevent demagnetization.
Solution Approach 2:
The protection level parameter is modified based on temperature conditions. The control device changes the overcurrent protection level parameter according to the detected motor temperature, enabling the system to optimize between performance and protection across different operating conditions.
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
Enables full motor performance throughout the temperature range and enhances reliability by dynamically adjusting the overcurrent protection level, preventing unnecessary interruptions and maintaining high output torque.
Implementation Method 1
an inverter to perform field weakening control for the motor, thereby driving the motor at a variable speed
Implementation Method 2
a first detector to output a first detection signal corresponding to a motor drive current supplied to the motor by the inverter
Implementation Method 3
a rotor having a neodymium rare earth permanent magnet, principal ingredients of which are neodymium, iron and boron
Data Source
AI summary
A driving device drives a motor including a rotor having a neodymium rare earth magnet. The driving device includes an inverter, a first detector that outputs a first detection signal corresponding to a motor driving current supplied to the motor, a protection level setting unit that sets an overcurrent protection level, a second detector that outputs a second detection signal corresponding to a driving state of the motor, and a control device. The control device executes first control of lowering the motor driving current immediately after the motor driving current corresponding to the first detection signal exceeds the overcurrent protection level. When the protection level setting unit lowers the overcurrent protection level to a new current level based on the second detection signal, the control device executes second control of lowering the motor driving current to a level lower than the new current level.