Adaptive Two-Level Three-Level Inverter Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power conversion apparatuses, particularly those using three-level inverters, face increased conduction losses and element count when dealing with variable direct-current voltage and alternating-current output, leading to inefficiencies, especially at low direct-current voltages or high outputs.
Innovation Solution
A power conversion apparatus with a configuration that includes semiconductor valve devices connected in series, alternating-current switches with diodes in inverse parallel, and a comparison circuit to determine optimal two-level or three-level operation based on insolation and current conditions, allowing for adaptive operation to minimize losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a three-level inverter circuit is used, then filter miniaturization and total loss reduction are achieved, but device complexity and conduction loss increase under variable direct-current voltage and alternating-current output conditions
Solution Approach 1:
The patent implements dynamic switching between two-level and three-level inverter operations based on real-time detection of direct-current voltage and alternating-current output conditions. The control unit determines the optimal operation mode and switches accordingly, making the system adaptive rather than static. This resolves the contradiction by allowing the system to use the simpler two-level configuration when appropriate while retaining the efficiency benefits of the three-level configuration when needed.
Solution Approach 2:
The patent changes the operational parameters of the inverter circuit by switching between two distinct operation modes (two-level and three-level) based on varying electrical conditions. This parameter change allows the system to optimize performance across different operating scenarios, reducing both device complexity and energy loss adaptively.
2Volume of stationary object
If a three-level inverter circuit is used, then filter miniaturization is achieved, but conduction loss increases at low direct-current voltage or high output conditions
Solution Approach 1:
The system dynamically selects between two-level and three-level operation modes based on real-time electrical conditions. When direct-current voltage is low or alternating-current output is high, the system switches to two-level operation to minimize conduction loss, while maintaining the capability for three-level operation when conditions favor filter miniaturization benefits.
3Loss of energy
If the inverter circuit is designed for constant direct-current voltage and constant output, then optimal performance is achieved, but adaptability to variable conditions deteriorates
Solution Approach 1:
The patent implements a dynamic control system that continuously monitors direct-current voltage and alternating-current output conditions, then adaptively switches between two-level and three-level inverter operations. This dynamic adaptation allows the system to maintain optimal conversion loss performance across varying operating conditions, resolving the contradiction between optimized design and adaptability.
Solution Approach 2:
The inverter circuit is designed to perform multiple functions by supporting both two-level and three-level operation modes within the same hardware configuration. This multi-functionality allows the system to adapt to various operating conditions while maintaining efficient power conversion, achieving both optimized performance and versatility.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
There is provided a power conversion apparatus including a power converter being so configured that an alternating-current switch constituted of a series connection of two valve devices each constituted of a semiconductor element and a diode connected in inverse parallel with the semiconductor element is connected between a connection point of the valve devices and a connection point of the direct-current power supplies in each arm, and each of the alternating-current switches is turned on or off, thereby enabling the power converter to perform three-level operation or two-level operation. The power conversion apparatus includes a comparison circuit (9) which compares a determination element related to a loss in the power converter with a switching reference value and outputs a determination instruction when a difference has occurred between the determination element and the switching reference value, a determination circuit (11) which determines whether the determination element is greater or less than the switching reference value when having received a determination instruction from the comparison circuit (9), and outputs a two-level operation switching instruction when the determination element is greater than or equal to the switching reference value, and a switching circuit (12) which, when having received a two-level operation switching instruction from the determination circuit (11), turns off the alternating-current switch and turns on the valve devices in the arm sequentially, thereby bringing the power converter into a two-level operation state.