Motor control device
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Solution Overview
Problem
Conventional motor control devices experience efficiency reduction and electrical impacts due to pulsation in peak current values when load changes occur, such as during refrigerant discharge, leading to increased maximum phase current values.
Innovation Solution
A motor control device that detects phase currents, sets a target d-axis current, and corrects it based on the average deviation between target and actual currents, as well as peak current values and rotational speeds, to suppress pulsation and reduce maximum current values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current feedback control is performed based on deviation between target and actual d-axis current, then motor control precision is improved, but peak current pulsation increases when load changes occur
Solution Approach 1:
The patent introduces a feedback mechanism where the calculated average value of absolute deviations is fed back to correct the target d-axis current. This feedback loop continuously adjusts the target current based on actual performance, suppressing peak current pulsation while maintaining control precision.
Solution Approach 2:
The patent dynamically changes the target d-axis current parameter by adding a correction amount derived from the average deviation. This parameter adjustment compensates for load variations and prevents excessive current pulsation while maintaining accurate current control.
2Stability of the object's composition
If target d-axis current is corrected based on average deviation, then peak current pulsation is suppressed, but control system complexity increases
Solution Approach 1:
The patent calculates the average value of absolute deviations over a predetermined period before applying correction to the target current. This preliminary calculation smooths out transient fluctuations and provides a stable correction basis, reducing the need for complex real-time control algorithms.
Solution Approach 2:
The patent introduces an intermediate correction amount that mediates between the original target current and the actual current requirements. This correction amount, derived from average deviation calculations, acts as a buffer that simplifies the control logic while achieving stable current regulation.
3Adaptability or versatility
If peak current value increases due to load pulsation, then motor can handle load changes, but motor efficiency decreases and electrical impacts on inverter increase
Solution Approach 1:
The patent dynamically adjusts the target d-axis current based on actual load conditions by incorporating deviation correction. This dynamic adjustment allows the motor to adapt to load changes efficiently without generating excessive current peaks, thereby maintaining motor efficiency while handling varying loads.
Solution Approach 2:
The patent converts the harmful effect of current deviation into a beneficial correction mechanism. By calculating the average absolute deviation and using it to adjust the target current, the system transforms what would be control error into a useful adaptation mechanism that improves efficiency while maintaining load adaptability.
Data Source
AI summary
In a motor control device, a voltage phase detecting unit sets a voltage phase of applied voltage to be applied to a motor based on a deviation between a target d-axis current set by a target d-axis current setting unit and an actual d-axis current detected by a rotor position detecting unit and an actual rotational speed detected by a rotational speed detecting unit. Here, a correction amount calculating unit determines whether or not a rotor has rotated by one period of mechanical angle based on the rotor position detected by the rotor position detecting unit and calculates an average value of deviations between target d-axis current and actual d-axis current in each period of mechanical angle as a correction amount, and a second addition/subtraction unit corrects a target d-axis current by a correction amount.