Motor Control Device Current Phase Map for Vibration Reduction
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Solution Overview
Problem
Existing motor control devices fail to effectively address the issue of quietness (low vibration and sound noise) in motors, particularly when mounted on vehicles, without compromising control stability or increasing the motor's size and weight.
Innovation Solution
A motor control device that generates current instructions to suppress vibration and sound noise by using a current map to determine the current phase for each torque, restricting d-axis and q-axis current variations, and correcting the current instruction to minimize radial magnetic force fluctuations, thereby improving quietness without hardware-based measures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional motor control methods (id=0 control, maximum torque control, field-weakening control) are used, then speed and torque controllability are maintained, but vibration and sound noise increase
Solution Approach 1:
The patent changes the control parameters by introducing a current phase adjustment mechanism that varies the current phase according to the torque command value. This parameter change allows the system to maintain control stability while reducing vibration and sound noise by optimizing the current injection timing relative to the rotor position.
Solution Approach 2:
The patent implements a dynamic control approach where the current phase is not fixed but varies dynamically based on the torque command value. This dynamic adjustment allows the system to adapt to different operating conditions and minimize vibration across various torque levels while maintaining stable control.
2Object-affected harmful factors
If hardware-based vibration reduction measures are implemented, then quietness is improved, but motor size and weight increase
Solution Approach 1:
The patent replaces hardware-based vibration reduction measures with a control-based solution. Instead of adding physical dampers or modifying the motor structure, the invention uses intelligent current control to minimize vibration sources, thereby reducing quietness without increasing motor weight or size.
3Power
If current phase is optimized for maximum torque, then torque efficiency is improved, but vibration increases
Solution Approach 1:
The patent introduces a torque-dependent current phase adjustment that modifies the optimal current phase based on the torque command value. This parameter change allows the system to balance torque efficiency and vibration reduction by deviating from the maximum torque current phase when vibration becomes excessive at certain torque levels.
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
The solution effectively enhances motor quietness while maintaining control stability and avoiding increases in size and weight, reducing vibration and sound noise through targeted current control strategies.
Implementation Method 1
fluctuation in a radial direction component of a magnetic force which acts between a rotor and a stator
Data Source
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AI summary
A current instruction generation unit (102) generates a d-axis current instruction (Id*) and a q-axis current instruction (Iq*) based on a torque instruction (TR) for an AC motor, using a map in which a current instruction capable of lowering noise (vibration and sound noise) (low-noise current instruction) generated from the AC motor is determined in advance for each torque of the AC motor. Then, a signal (PWI) for driving an inverter is generated based on the generated d-axis current instruction (Id*) and the q-axis current instruction (Iq*).