Linear motor control apparatus and compressor equipped with the same
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Solution Overview
Problem
Existing linear motor control systems face challenges in accurately estimating resonance frequency due to noise interference from search coils and complex wiring, and they lack suitable start-up control to secure the amplitude of the mover effectively.
Innovation Solution
A linear motor control apparatus that employs two operation modes: one where the amplitude of the AC voltage is monotonically increased while keeping the frequency constant, and another where the frequency is changed while keeping the amplitude constant, allowing for improved estimation of the resonance frequency immediately after start-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a search coil is used to detect the phase of induced voltage for resonance frequency estimation, then the resonance frequency can be detected, but the wiring becomes complicated and the search coil is easily affected by noise, reducing measurement precision
Solution Approach 1:
The patent extracts and eliminates the search coil component from the system. Instead of using a separate search coil to detect induced voltage phase, the invention uses the main winding's voltage and current signals directly for resonance frequency estimation, thereby removing the source of wiring complexity and noise interference.
Solution Approach 2:
The patent introduces a phase difference calculation mechanism that uses the voltage and current signals from the main winding as intermediaries to estimate resonance frequency. This mediator approach avoids the need for direct search coil measurements while still achieving accurate phase difference detection for resonance identification.
2Measurement precision
If a search coil is used to detect the phase of induced voltage for resonance frequency estimation, then the resonance frequency can be detected, but the search coil is easily affected by noise, reducing measurement precision
Solution Approach 1:
The patent removes the search coil that is susceptible to noise interference and instead uses signals from the main winding, which are less affected by external noise, thereby improving measurement precision.
Solution Approach 2:
The patent creates a virtual copy of the search coil's detection function by using the main winding's voltage and current signals to calculate phase difference and estimate resonance frequency, achieving the same measurement goal without the physical search coil that introduces noise.
3Force
If the amplitude of AC voltage is increased to secure mover amplitude at start-up, then the mover amplitude is secured, but the resonance frequency estimation accuracy deteriorates due to insufficient amplitude control
Solution Approach 1:
The patent implements dynamic control of voltage amplitude during start-up, adjusting the amplitude in a controlled manner rather than simply increasing it. This dynamic adjustment allows the system to secure sufficient mover amplitude while maintaining conditions favorable for accurate resonance frequency estimation through the two-mode operation sequence.
Solution Approach 2:
The patent performs preliminary amplitude control in Mode (1) before resonance frequency estimation in Mode (2). By first establishing appropriate mover amplitude through controlled voltage increase, the system prepares the optimal conditions for subsequent accurate resonance frequency measurement without the amplitude control issues that would compromise estimation accuracy.
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 enhances the accuracy of resonance frequency estimation and ensures stable start-up by controlling the stroke and frequency of the linear motor, reducing noise interference and improving efficiency.
Implementation Method 1
a linear motor having a winding 8 to which an AC voltage is applied and a mover 6 connected to an elastic body 23
Implementation Method 2
a linear motor which drives a mover connected to an elastic body 23 at a mechanical resonance frequency in a system of the elastic body 23 and the mover 6
Data Source
AI summary
Provided is a linear motor control apparatus capable of improving estimation accuracy of a resonance frequency immediately after start, and a compressor equipped with the linear motor control apparatus. A linear motor control apparatus includes a winding to which an AC voltage is applied and a mover which is connected to an elastic body, in which the linear motor control apparatus includes an operation mode (1) which monotonously increases amplitude of the AC voltage while keeping a frequency of the AC voltage substantially constant, and an operation mode (2) which changes the frequency of the AC voltage while keeping the amplitude of the AC voltage substantially constant, and executes the operation mode (1) and the operation mode (2) in this order.