EV Power Converter Waveform Control With Lower Switching Loss
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Solution Overview
Problem
Conventional power conversion devices for electric vehicles have inefficiencies due to high voltage requirements, leading to increased losses, distorted AC waveforms, and mismatched performance with vehicle traveling characteristics.
Innovation Solution
A power conversion device with a configuration that includes a first converter and a first generator, capable of converting battery power into specific output waveforms, using switching elements to control the flow of power and generate AC power suitable for electric vehicle motors, optimizing voltage and waveform for efficient power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high withstand voltage component is used to withstand high voltage in the inverter, then the voltage requirement is met, but the ON resistance increases and power loss increases
Solution Approach 1:
The patent divides the power conversion function into two separate stages: a first conversion stage that converts DC power to AC power, and a second conversion stage that adjusts the voltage level. This segmentation allows each stage to operate at optimal voltage levels, avoiding the need for high-voltage components in the first stage, thereby reducing ON resistance and power loss while still meeting the required output voltage.
Solution Approach 2:
The patent introduces an intermediate conversion stage between the DC power source and the final AC output. This intermediary stage converts DC to AC at lower voltage first, then a transformer or second converter boosts the voltage to the required level. This approach eliminates the need for high-voltage switching components, reducing power loss while maintaining reliability.
2Productivity
If switching control is performed to convert DC power into AC power, then power conversion is achieved, but harmonics are generated and AC waveform is distorted
Solution Approach 1:
The patent segments the power conversion process into distinct stages: first converting DC to AC with proper waveform control, then separately adjusting voltage levels. This allows the first stage to focus on generating clean AC waveforms with minimal harmonics, while the second stage handles voltage transformation, thereby reducing overall waveform distortion and harmonic generation.
Solution Approach 2:
The patent implements control mechanisms that monitor the AC waveform quality and adjust switching patterns to minimize harmonics. By using feedback control in the first conversion stage, the system can maintain sinusoidal waveforms and reduce distortion, improving power quality while maintaining conversion efficiency.
3Power
If the inverter is configured for high voltage boosting to guarantee maximum traveling capacity, then peak performance is achieved, but the configuration does not match normal traveling characteristics
Solution Approach 1:
The patent employs dynamic voltage control where the first conversion stage operates at optimal lower voltage for normal conditions, and the second stage provides variable voltage boosting only when needed. This dynamic configuration allows the system to adapt to different traveling requirements, operating efficiently at lower power levels during normal travel while maintaining the capability to deliver maximum power when required.
Solution Approach 2:
The patent creates a multi-functional power conversion system where the first converter handles the primary DC-to-AC conversion applicable to all operating conditions, and the second conversion stage provides optional voltage boosting for specific high-power requirements. This universal configuration matches the diverse traveling characteristics of electric vehicles, providing appropriate performance for both normal and maximum capacity operations.
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 enhances power conversion efficiency, reduces losses, and matches power conversion characteristics with electric vehicle traveling requirements, improving performance and reducing component stress.
Implementation Method 1
DC power is converted into AC power by performing a switching control process for the ON or OFF time of a battery, which is a power source, using an inverter
Implementation Method 2
the inverter boosts the voltage of the battery and supplies the boosted voltage to the electric motor
Data Source
AI summary
A power conversion device includes a first converter configured to convert at least first battery power output by a first battery into first output power of a first voltage waveform based on an output waveform profile that has been input or set and output the first output power and a first generator configured to generate and output second output power based on the first battery power. Third output power of an alternating current (AC) control waveform generated by adding the first output power to the second output power is supplied to a load.