Inverter Switching Control for Surge Reduction
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Solution Overview
Problem
Existing power conversion devices face inefficiencies when using a mix of switching elements with different electric characteristics, as they struggle to finely control switching timings, leading to increased surges and reduced system efficiency.
Innovation Solution
A power conversion device with an inverter circuit that includes parallel-connected switch sections, each comprising a first and second switching element with independent control signal lines, allowing for distinct switching control signals to be applied to each element, thereby synchronizing their switching timings and reducing surge occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same control signal is used for both switching elements, then the control circuit is simple, but the switching timings cannot be finely controlled
Solution Approach 1:
The control signal is segmented into multiple levels (first level and second level positive voltage levels) to differently control the first and second switching elements. The controller outputs different control signals to the first and second switching elements based on the same input signal, enabling fine control of switching timings while maintaining a relatively simple control circuit structure.
2Adaptability or versatility
If switching elements with different electric characteristics are used, then the application range is widened, but the surge occurrence increases
Solution Approach 1:
The controller performs preliminary action by outputting control signals at different levels before the switching elements actually switch. When the input signal transitions from low to high level, the controller first outputs a first level positive voltage to prepare the first switching element, then outputs a second level positive voltage to control the second switching element, thereby distributing surge generation timing and reducing overall surge occurrence.
3Device complexity
If the switching elements are controlled to switch simultaneously, then the control is simple, but the transient current magnitude increases
Solution Approach 1:
The controller implements periodic action by using multi-level control signals with different voltage levels to sequentially control the switching elements. The control signal transitions through different levels (low level, first level positive voltage, second level positive voltage) to create staged switching action, which distributes the transient current over time and reduces peak current magnitude.
Data Source
AI summary
A power conversion device that includes an inverter circuit in which arms are connected in parallel to each other between a DC positive terminal and a DC negative terminal in accordance with a number of phases of alternating currents of the plurality of phases, the arms for respective phases each including two switch sections that are connected in series and to be brought into conduction in an on state and out of conduction in an off state, and a connection point between the two switch sections of each of the arms is set as an AC input or output point of each phase; and a controller that outputs switching control signals for performing switching control on the switch sections.