Motor Control Apparatus Resonance Suppression
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Solution Overview
Problem
Existing motor control apparatuses face inefficiencies due to resonance in the booster circuit, which affects energy efficiency and switching losses when using PWM signals for motor control.
Innovation Solution
A motor control apparatus that temporarily inverts the voltage polarity of square wave voltage based on the phase difference between voltage and current commands, specifically designed to suppress resonance in the booster circuit by adjusting the pulse pattern during resonance regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PWM control is used to drive the motor, then the motor can be controlled with smooth torque, but resonance is generated in the booster circuit due to the sixth electrical frequency matching the LC circuit resonance frequency
Solution Approach 1:
The invention changes the voltage waveform shape from sinusoidal PWM to square wave, which fundamentally alters the frequency spectrum. This parameter change eliminates the sixth harmonic component that causes resonance in the LC circuit, thereby resolving the contradiction between motor control stability and energy efficiency by avoiding resonance losses
2Loss of energy
If square wave voltage is used to drive the motor, then switching losses are reduced and energy efficiency is improved, but resonance is generated in the booster circuit
Solution Approach 1:
The invention introduces periodic polarity inversion of the square wave voltage at specific timing (when the voltage and current have the same sign). This periodic modification changes the harmonic content of the voltage waveform, specifically eliminating the sixth electrical frequency component that causes LC circuit resonance, thereby maintaining both energy efficiency and circuit stability
Solution Approach 2:
The invention converts the harmful resonance effect into a beneficial control strategy by deliberately inverting voltage polarity during specific periods. This control action transforms what would be a harmful resonance condition into an opportunity to shape the voltage waveform and eliminate problematic frequency components, turning a potential harm into a solution
3Loss of energy
If the voltage polarity is temporarily inverted during resonance region operation, then resonance in the booster circuit is suppressed, but the control complexity increases
Solution Approach 1:
The invention uses feedback control by continuously monitoring the relationship between voltage and current waveforms. The control system detects when voltage and current have the same sign (indicating energy flow direction) and uses this feedback information to determine the optimal timing for polarity inversion, thereby automatically suppressing resonance without requiring complex external control mechanisms
Solution Approach 2:
The control system uses the inherent characteristics of the voltage and current waveforms themselves to generate the control signal. By detecting the sign relationship between voltage and current, the system automatically determines when polarity inversion should occur, making the control mechanism self-regulating and reducing the need for additional complex control circuitry
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 energy efficiency and reduces switching losses by avoiding resonance in the booster circuit, improving motor control performance compared to traditional PWM control methods.
Implementation Method 1
Depending on an operating point of the motor, the LC circuit resonates (i.e. resonance is generated in the booster circuit)
Data Source
AI summary
A motor control apparatus includes: a booster circuit electrically connected to a battery; and an inverter electrically connected to the booster circuit at one end and electrically connected to a motor at another end. The motor control apparatus is provided with a controller configured to control the inverter to output square wave voltage to the motor, thereby driving the motor. The controller is configured to control the inverter to temporarily invert voltage polarity associated with the square wave voltage, on the basis of a phase difference between a voltage command associated with the motor and an electric current associated with the motor, on condition that an operating point of the motor is in a resonance region, which is an operation area in which resonance is generated in the booster circuit.