Motor Control Apparatus for Accurate Magnetic-Pole Position Estimation
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Solution Overview
Problem
Conventional motor control apparatuses face challenges in accurately estimating the magnetic-pole position of a rotor during startup or when the rotor is rotating, due to reduced current change differences caused by magnetic saturation, leading to decreased accuracy and increased complexity in circuit design.
Innovation Solution
A motor control apparatus with a power conversion unit and control unit that performs proportional-integral control on current deviations and uses high-frequency currents to estimate and correct the magnetic-pole position, integrating the q-axis current control to determine polarity, thereby simplifying the circuit and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse voltage is applied to perform polarity determination during current control, then the magnetic-pole position can be estimated, but the current control effect reduces the difference in current change due to magnetic saturation, decreasing polarity determination accuracy
Solution Approach 1:
The patent introduces a bandpass filter as an intermediary component to separate the pulse voltage signal from the current control signal. The filter extracts the high-frequency component caused by the pulse voltage while removing the low-frequency current control component, enabling accurate polarity determination without interfering with current control effectiveness
Solution Approach 2:
The patent increases the amplitude of the pulse voltage to enhance the magnetic saturation effect. By changing the voltage parameter to a higher amplitude, the current change difference due to magnetic saturation becomes more pronounced, improving polarity determination accuracy despite the presence of current control
2Measurement precision
If bandpass filter is used to avoid pulse voltage band interference with current control, then polarity determination accuracy is maintained, but circuit complexity increases
Solution Approach 1:
The bandpass filter serves as an intermediary signal processing component that selectively passes the pulse voltage frequency band while blocking the current control frequency band. This allows the system to maintain polarity determination accuracy by isolating the relevant signal component without requiring complex multi-component circuits
3Measurement precision
If high amplitude pulse voltage is applied to overcome current control effect, then polarity determination accuracy is improved, but voltage requirements and circuit complexity increase
Solution Approach 1:
The patent deliberately increases the pulse voltage amplitude parameter to a high level to ensure that the magnetic saturation effect produces a detectable current change difference. This parameter change compensates for the suppressive effect of current control, maintaining polarity determination accuracy without requiring additional circuit components
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 allows for accurate estimation of the magnetic-pole position even when the rotor is rotating, reducing the need for complex bandpass filters and high-amplitude pulse voltages, enhancing the accuracy and simplicity of the control system.
Implementation Method 1
estimating the magnetic-pole position of a rotor of the motor on the basis of a high-frequency current flowing into the motor by controlling the power conversion unit
Implementation Method 2
applying a pulse voltage varying between positive and negative voltages to the motor to magnetically saturate the magnetic flux in the d-axis of the motor, detecting the difference in change of the current flowing into the motor to determine the polarity
Data Source
AI summary
A motor control apparatus according to an embodiment includes a power conversion unit and a control unit. The power conversion unit supplies power to a motor having salient pole characteristic. The control unit performs proportional-integral control on the deviation between a current reference and a current flowing into the motor to generate a voltage reference, and controls the power conversion unit on the basis of the voltage reference. The control unit estimates the magnetic-pole position of a rotor of the motor on the basis of a high-frequency current flowing into the motor by controlling the power conversion unit, and corrects the estimated magnetic-pole position on the basis of an integrated value of the proportional-integral control.