Motor-Driving System Pulse Waveform Optimization
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Solution Overview
Problem
Existing motor-driving systems for hybrid and electric cars fail to effectively minimize power loss and current distortion in power converters and motor generators, neglecting iron loss and torque ripple caused by harmonic components.
Innovation Solution
A motor-driving system with a three-phase full-bridge power converter and a control unit that generates a pulse waveform with optimized pulse width and phase angle to minimize power loss, current distortion, and torque ripple by selecting pulse waveforms that cancel even and odd harmonics, reducing the number of switching times and overall system losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional PWM switching is used to convert DC power to AC power, then power conversion is achieved, but power loss and current distortion increase due to harmonic components
Solution Approach 1:
The patent applies parameter changes by optimizing the PWM pulse waveform parameters (pulse width, amplitude, phase angle) to minimize harmonic components. The control unit calculates optimal pulse waveform parameters that reduce power loss and current distortion while maintaining effective power conversion from DC to AC power.
2Object-generated harmful factors
If switching elements are switched frequently to reduce harmonic components, then current distortion is reduced, but switching losses increase
Solution Approach 1:
The patent optimizes the switching frequency and pulse waveform parameters to find the optimal balance between reducing current distortion and minimizing switching losses. The control unit calculates pulse waveforms with optimized parameters that reduce harmonic components while limiting excessive switching operations that would increase power loss.
3Loss of energy
If pulse waveform parameters are optimized to minimize power loss, then system efficiency improves, but control complexity increases
Solution Approach 1:
The control unit implements feedback control by continuously monitoring system parameters and adjusting pulse waveform parameters to minimize power loss. The control unit calculates optimal pulse waveforms based on system conditions and applies them to the switching elements, creating a closed-loop control system that adapts to changing operating conditions.
Solution Approach 2:
The control unit performs preliminary calculation of optimal pulse waveform parameters before applying them to the switching elements. By pre-calculating the optimized pulse waveforms based on desired output characteristics and system parameters, the control system reduces real-time computational complexity while maintaining optimization benefits.
4Loss of energy
If harmonic components are eliminated to reduce iron loss, then motor generator efficiency improves, but torque ripple increases
Solution Approach 1:
The patent optimizes pulse waveform parameters to achieve a balance between reducing harmonic components (which causes iron loss) and maintaining smooth torque output. The control unit calculates pulse waveforms that minimize harmful harmonics while preserving the fundamental frequency components necessary for smooth motor generator operation and reduced torque ripple.
Data Source
AI summary
The invention includes a three-phase full-bridge power converter, a motor generator driven by the power converter, a pulse number generator which determines the number of pulses included in the driving signal for one electrical cycle, a voltage command generator which determines a modulation factor and a phase angle of driving voltage, and a pulse generator which generates the driving signal, and, in this invention, the pulse generator generates the driving signal having a pulse waveform which minimizes power loss in the power generator and the motor generator according to the number of pulses, the modulation factor, and the phase angle.