Single-Phase Inverter Segmentation for EVSE Power Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high cost and time-consuming regulatory approval processes for obtaining three-phase inverters make it difficult to acquire safe and reliable power converters for electric vehicle service equipment (EVSE) that require three-phase 240-volt AC input, especially when using DC energy storage devices like lithium-ion batteries.
Innovation Solution
A system utilizing multiple inexpensive single-phase inverters connected in parallel to produce a three-phase AC output suitable for powering three-phase EVSE, with staggered timing and rectification to prevent simultaneous polarity changes, and an optional capacitor to mitigate voltage drops, eliminating the need for additional safety approvals and reducing costs significantly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three-phase inverters are used to convert DC energy storage output to three-phase AC input for EVSE, then the EVSE can be powered reliably, but the cost and time for safety approval become prohibitively expensive and time-consuming
Solution Approach 1:
The patent divides the three-phase power conversion system into three separate single-phase inverters instead of using one integrated three-phase inverter. Each single-phase inverter is independently safety-approved, eliminating the need for costly and time-consuming approval of a custom three-phase inverter system while maintaining reliable power conversion capability.
Solution Approach 2:
The patent uses standard single-phase inverters that are universally available and already safety-approved for various applications. These universal single-phase units can be combined to perform the specialized function of powering three-phase EVSE, avoiding the need for custom-engineered three-phase inverters that require new safety certifications.
2Adaptability or versatility
If all-in-one three-phase inverters are used, then complete DC-to-three-phase AC conversion is achieved, but the cost becomes prohibitively expensive
Solution Approach 1:
The patent segments the expensive all-in-one three-phase inverter into three inexpensive single-phase inverters. By dividing the system, each component can be sourced from mass-market suppliers at lower costs, while the combined system achieves the same three-phase power conversion capability needed for EVSE operation.
Solution Approach 2:
The patent merges three separate single-phase inverters into a coordinated three-phase power conversion system. The inverters work together with synchronized timing and phase shifting to produce the required three-phase AC output, achieving the functionality of an all-in-one inverter at a fraction of the cost.
3Quantity of substance
If single-phase inverters are used instead of three-phase inverters, then cost is reduced significantly, but simultaneous polarity changes in all three phases may occur
Solution Approach 1:
The patent applies preliminary timing adjustments and phase shifting to the three single-phase inverters before they operate. By pre-synchronizing their operation and offsetting their polarity transition times, the system prevents simultaneous zero-voltage moments that would destabilize the three-phase output, ensuring reliable EVSE operation.
Solution Approach 2:
The patent introduces timing control and phase shifting as intermediary mechanisms between the three single-phase inverters. These control elements coordinate the inverters' operation to prevent simultaneous polarity changes, acting as mediators that ensure stable three-phase output despite the use of independent single-phase units.
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 solution provides a cost-effective and efficient means to convert DC energy storage into suitable three-phase AC for EVSE, reducing the financial and temporal burdens associated with traditional three-phase inverter systems while ensuring safety and reliability.
Implementation Method 1
Energy storage devices such as lithium-ion batteries do not innately provide this power form and thus require that EVSE be connected to the energy storage devices through DC-to-AC power converters that bring the voltage output of the energy storage devices to a form suitable for the EVSE to charge a vehicle
Implementation Method 2
In some embodiments, the output of the single-phase inverters or EVSE passes through a rectifying means, which may be internal to the EVSE
Implementation Method 3
In some other embodiments, there is an inexpensive, long-lasting capacitor installed in the system to mitigate the drop in the maximum voltage of the three-phase signal during any brief intervals where all three of the inverters transition polarity concurrently
Data Source
AI summary
A system and method of use of a three-phase inverter driver includes three single-phase inverters that are connected to the three-phase AC input of electric vehicle supply equipment (EVSE) so that each of the single-phase inverters provide one of the three phases of the AC signal used by the EVSE. The single-phase inverters are rectified and either have variance in their output frequencies or have their phases staggered so that the maximum voltage provided to the EVSE remains at a consistently high level. In some cases, the three phases each cross polarity simultaneously, resulting in a drop in the maximum three-phase voltage, so low-capacity capacitors are used in conjunction with the inverters to bridge these gaps in voltage. These systems and methods use readily available, inexpensive components that have regulatory safety-approval and therefore may allow implementation on a vehicle or with a load leveling energy storage system.