Magnet Motor Power Converter for Sinusoidal Current Control
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Solution Overview
Problem
Existing power converter systems struggle to maintain sinusoidal current in magnet motors when the induced voltage is a square wave, leading to current pulsation due to odd harmonic components.
Innovation Solution
A power converter apparatus that calculates the gain of the magnetic flux component of the q-axis and uses this information to generate d-axis and q-axis induced voltage command values without requiring stored induced voltage data, thereby controlling the magnet motor current to be sinusoidal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If induced voltage data is stored in the controller's memory to generate d-axis and q-axis induced voltage command values, then the current sinusoidal control is achieved, but the device complexity and memory requirements increase
Solution Approach 1:
The patent extracts only the essential induced voltage coefficient from the complete induced voltage data, storing this single coefficient in memory rather than the full induced voltage waveform data. This extraction principle reduces memory requirements while maintaining the capability to generate accurate d-axis and q-axis induced voltage command values through real-time calculation using the stored coefficient and current rotational position.
Solution Approach 2:
The patent changes the stored parameter from complete induced voltage data (waveform information) to a simplified induced voltage coefficient. This parameter transformation allows the system to reconstruct the necessary voltage command values through calculation rather than direct data retrieval, reducing memory storage requirements while maintaining control precision.
2Device complexity
If square wave induced voltage is applied to the magnet motor, then the device complexity is reduced, but current pulsation occurs due to odd harmonic components
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the rotational position and uses the stored induced voltage coefficient to calculate and adjust the d-axis and q-axis induced voltage command values in real-time. This feedback loop compensates for the harmonic components introduced by the square wave induced voltage, eliminating current pulsation while maintaining the simplicity of the square wave waveform.
Solution Approach 2:
The patent dynamically adjusts the voltage command parameters (d-axis and q-axis components) based on the rotational position and induced voltage coefficient, transforming the simple square wave induced voltage into controlled voltage commands that cancel out harmful harmonic effects, thereby eliminating current pulsation without changing the fundamental square wave nature of the induced voltage.
Data Source
AI summary
A power converter apparatus comprising: a power converter that outputs signal to the magnet motor to vary the output frequency, output voltage and output current of the magnet motor, a control unit controls the power converter, wherein the control unit calculating the gain of the magnetic flux component of the q-axis, which varies with the phase of the magnet motor, calculating the d-axis induced voltage command value based on a value of the induced voltage coefficient, frequency estimates or frequency command value, and the gain of the flux component of the q-axis.