Hybrid Vehicle Inverter Harmonic Suppression via Phase-Shifted Control
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Solution Overview
Problem
Existing AC voltage output systems in hybrid vehicles generate harmonics of counter-electromotive force during motor revolution, leading to distortion in the AC voltage supplied to load devices, which can cause malfunctions and require dedicated inverters.
Innovation Solution
An AC voltage output apparatus with star-connected polyphase AC motors, inverters, and a control device that generates a harmonic voltage instruction opposite to the counter-electromotive force harmonics, suppressing these harmonics and eliminating the need for dedicated inverters by using software configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated inverter is used to generate AC voltage, then the AC voltage can be supplied to load devices, but the system complexity and hardware requirements increase
Solution Approach 1:
The motor inverter is designed to perform multiple functions: both driving the motor and generating AC voltage for external load devices. The inverter switches control the motor winding to function as a generator, allowing the same hardware to supply power both to the motor and to external AC loads, thereby eliminating the need for a dedicated inverter.
Solution Approach 2:
The patent combines the motor drive inverter and the AC voltage generation inverter into a single integrated system. The motor inverter and generator inverter share the same hardware resources including switching devices, DC bus, and control unit, merging two previously separate functions into one unified system.
2Productivity
If the motor revolves to generate AC power, then power can be supplied to external devices, but harmonic distortion is generated in the AC voltage
Solution Approach 1:
The control unit extracts and separates the harmonic components from the generated AC voltage by independently controlling the switching patterns of the inverter. By taking out the harmful harmonic elements through selective switching control, the system can supply AC power while minimizing distortion effects on the output voltage.
Solution Approach 2:
The control unit dynamically adjusts switching parameters and control signals based on the motor's rotational speed and load conditions. By changing the switching frequency and duty cycle parameters, the system optimizes the balance between power generation capability and harmonic distortion levels, adapting to different operating conditions.
3Productivity
If the motor revolves to generate AC voltage, then external devices can be powered, but counter-electromotive force harmonics are generated
Solution Approach 1:
The control unit continuously monitors the motor's rotational speed and the generated voltage characteristics, using this feedback information to adjust the inverter switching control. By detecting the counter-electromotive force harmonics in real-time and adjusting the switching patterns accordingly, the system minimizes the generation of harmful harmonics while maintaining power generation capability.
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
The solution effectively suppresses harmonics, ensuring distortion-free AC voltage supply to load devices without the need for additional hardware, enhancing the reliability and efficiency of hybrid vehicle power supply systems.
Implementation Method 1
a dedicated inverter for converting a DC (Direct Current) voltage generated in the hybrid vehicle to AC 100V
Implementation Method 2
while the three-phase AC motor including a Y-connected three-phase coil as a stator coil is revolving, a harmonic of order of multiple of 3, of counter-electromotive force generated in the coil of each phase appears in a potential of the neutral point of the three-phase coil
Data Source
AI summary
A first inverter control unit includes a harmonic generation unit. The harmonic generation unit generates a harmonic voltage instruction having a phase opposite to a harmonic generated at a neutral point of a motor-generator when the motor-generator revolves, based on motor revolution number of the motor-generator. A PWM signal generation unit generates a signal based on a voltage instruction obtained by superimposing an AC voltage instruction from an AC output control unit and the harmonic voltage instruction from the harmonic generation unit onto each voltage instruction of U-phase, V-phase and W-phase from a conversion unit.