Current Source Inverter Overlap Period Control
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Solution Overview
Problem
Conventional current source inverters require additional control circuits and detectors to prevent switching loss and element destruction during commutation, which complicates the control of switching elements and increases the risk of damage.
Innovation Solution
A current source inverter with a predetermined overlap period during commutation, where the timing for driving switching elements is controlled to generate a sufficient overlap time for load current fluctuations, allowing resonant current to flow and reducing switching loss without the need for additional control circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional commutation control is used without overlap period, then switching elements can be controlled simply, but switching loss occurs and element destruction may happen due to overvoltage and current generation during commutation
Solution Approach 1:
The patent applies preliminary action by establishing a predetermined overlap period in the control program before commutation occurs. This overlap period is set in advance to ensure that the commutation source switching element is turned off after the commutation target switching element is turned on, preventing switching loss and overvoltage without requiring complex real-time detection or additional control circuits.
2Reliability
If additional control circuits and detectors are added to prevent switching loss and element destruction, then element reliability improves, but device complexity increases
Solution Approach 1:
The patent applies self-service by using the control program itself to provide the protective overlap period function. The control program automatically ensures that the commutation source switching element remains on for a predetermined overlap period after the commutation target switching element is turned on, making the system self-protecting without external detectors or additional control circuits.
3Ease of operation
If commutation is performed without overlap period, then switching elements can be controlled with simpler timing, but current and voltage generation during commutation causes element destruction
Solution Approach 1:
The patent applies preliminary anti-action by preemptively introducing an overlap period in the control program that prevents the harmful effects of commutation. The overlap period ensures that the commutation source switching element is not turned off immediately when the commutation target is turned on, thereby preventing overvoltage and current generation that would otherwise damage the switching elements.
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
This approach enables zero current and zero voltage switching during commutation, reducing switching losses and preventing element damage without additional control circuits, thus simplifying the control of switching elements in current source inverters.
Implementation Method 1
a resonant circuit for supplying resonant current to switching elements in the multiphase inverter
Data Source
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Figure 3A~3D
AI summary
In controlling switching elements of a current source inverter, a switching loss in the switching element is prevented according to a normal switching operation for a commutation operation, without requiring any particular control. In the commutation operation of the current source inverter, a timing for driving the switching elements is controlled in such a manner that an overlap period is generated, during when both a switching element at the commutation source and a switching element at the commutation target are set to be the ON state, a resonant circuit is controlled based on the control of the switching elements having this overlap period, and resonant current of the resonant circuit reduces the switching loss upon commutation operation of the switching elements. By controlling the generation of the resonant current of the resonant circuit by using the control of the switching elements having the overlap period, the resonant current generated by this control renders current and voltage of the switching element at the commutation source to zero when commutation is performed, thereby reducing the switching loss in the commutation operation.