Motor Control Apparatus Reducing Radial Force Harmonics
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Solution Overview
Problem
Existing motor control systems for permanent-magnet synchronous motors face challenges in reducing vibration and noise caused by electromagnetic excitation forces, particularly the 6th-order radial force, which can lead to increased 8th-order radial force and resonance-related issues.
Innovation Solution
A motor control apparatus and method that determine and superpose d-axis and q-axis 6th-order harmonic currents on the respective 0th-order currents, adjusting their amplitudes and phases to specifically decrease both the 6th-order and 8th-order radial forces, using a circuit and integrated circuit device to implement these control values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an electrical angle 6th-order harmonic current is superposed on d-axis and q-axis currents to reduce the 6th-order radial force, then the 6th-order vibration and noise are suppressed, but the electrical angle 8th-order radial force significantly increases causing resonance
Solution Approach 1:
The patent changes the control parameters by introducing independent amplitude and phase control for both d-axis and q-axis 6th-order harmonic currents. By adjusting these four parameters (id6, θd6, iq6, θq6) according to specific mathematical relationships, the system can simultaneously minimize both 6th-order and 8th-order radial forces, resolving the contradiction between suppressing one harmonic order while avoiding excitation of another.
Solution Approach 2:
The patent implements dynamic adjustment of harmonic current parameters based on real-time operating conditions. The amplitude and phase of the 6th-order harmonic currents are continuously optimized according to the rotor position and operating state, allowing the system to adaptively minimize both 6th-order and 8th-order radial forces across different operating ranges, rather than using fixed parameter values.
2Manufacturing precision
If the amplitude and phase of 6th-order harmonic current are optimized to minimize 6th-order radial force, then 6th-order vibration is reduced, but 8th-order radial force increases due to resonance
Solution Approach 1:
The patent transforms the single-objective optimization problem into a multi-objective optimization by establishing mathematical relationships between the four harmonic current parameters. The control system minimizes a composite objective function that includes both 6th-order and 8th-order radial force components, achieving precise vibration control while maintaining resonance stability through coordinated parameter adjustment.
Solution Approach 2:
The patent implements a feedback mechanism where the actual vibration and noise levels are monitored, and the harmonic current parameters are continuously adjusted based on this feedback. The system uses the detected vibration characteristics to optimize the amplitude and phase of the 6th-order harmonic currents, ensuring that both 6th-order and 8th-order radial forces are minimized while maintaining system reliability.
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
Effectively reduces motor vibration and noise by minimizing both 6th-order and 8th-order radial forces, thereby mitigating resonance and improving operational stability.
Implementation Method 1
an electromagnetic excitation force generated in the radial direction of the motor excites the vibration of the stator. The electromagnetic excitation force in the radial direction is referred to as a 'radial force' and is generated between the teeth of the rotor and the stator.
Data Source
AI summary
A motor control apparatus includes a first circuit that determines a d-axis 0th-order current and a q-axis 0th-order current, a second circuit that determines a d-axis 6th-order harmonic current and a q-axis 6th-order harmonic current according to a position of the rotor, and a third circuit that determines, respectively, a value obtained by superposing the d-axis 6th-order harmonic current on the d-axis 0th-order current and a value obtained by superposing the q-axis 6th-order harmonic current on the q-axis 0th-order current as a d-axis current command value and a q-axis current command value. An amplitude id6 and a phase θd6 of the d-axis 6th-order harmonic current and an amplitude iq6 and a phase θq6 of the q-axis 6th-order harmonic current have values that decrease an electrical angle 6th-order radial force as compared with a case in which both of the amplitude id6 and the amplitude iq6 are zero and decrease an electrical angle 8th-order radial force as compared with a case in which the amplitudes id6 and iq6 and the phases θd6 and θq6 are values that minimize the electrical angle 6th-order radial force.