Bidirectional AC/DC Converter for EV Charging and Motor Drive
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Solution Overview
Problem
Existing power electronics systems for electric vehicles are bulky and costly due to separate AC/DC converters for battery charging and motor driving, which limits efficiency and fast charging capabilities.
Innovation Solution
A single bidirectional AC/DC converter with a switching block and electronic controller that can switch between charging and motor driving modes, using GaN HEMT switches for high-frequency operation, reducing bulkiness and cost while providing electrical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate AC/DC converters are used for battery charging and motor driving, then functional reliability is improved, but device complexity and volume increase
Solution Approach 1:
The patent combines the AC/DC converter and DC/AC inverter into a single integrated power conversion device. The AC/DC converter includes a rectifier bridge, DC link, and DC/AC inverter with shared control circuitry and power semiconductor devices, eliminating the need for separate converter units while maintaining both charging and motor driving functions through a unified architecture.
Solution Approach 2:
The integrated power conversion device performs multiple functions: it operates as an AC/DC converter for battery charging, as a DC/AC inverter for motor driving, and includes integrated control for both functions. The device can switch between charging mode and motor driving mode using the same hardware platform, achieving multi-functionality without requiring separate dedicated converters.
2Reliability
If separate AC/DC converters are used for battery charging and motor driving, then functional independence is improved, but volume and weight increase
Solution Approach 1:
The patent merges the AC/DC converter and DC/AC inverter into a single integrated unit with shared components including the rectifier bridge, DC link capacitor, power semiconductor devices, and control circuitry. This consolidation reduces the overall volume by eliminating redundant components and optimizing the spatial arrangement of shared elements.
Solution Approach 2:
The integrated power conversion device employs a nested structure where the DC/AC inverter is functionally nested within the AC/DC converter architecture. The inverter stage uses the DC link created by the rectifier bridge, and both stages share common control and support circuits, creating a compact nested configuration that minimizes volume.
3Reliability
If separate AC/DC converters are used for battery charging and motor driving, then functional specialization is improved, but cost increases
Solution Approach 1:
The patent combines two separate converter functions into one integrated device, reducing the total component count including power semiconductor devices, control circuits, and support components. This consolidation lowers manufacturing costs by reducing assembly complexity, minimizing the bill of materials, and enabling economies of scale in production.
Solution Approach 2:
The integrated power conversion device achieves both AC/DC conversion for charging and DC/AC inversion for motor driving using a single multi-functional platform. This universality eliminates the need to manufacture and stock separate specialized converters, reducing overall system cost while maintaining functional capability through software-controlled operation modes.
4Reliability
If bulky transformers and inductors are used for electrical isolation, then reliability is improved, but power density decreases
Solution Approach 1:
The patent increases the operating frequency of the power conversion device, which allows the use of smaller transformers and inductors for the same power level. The high-frequency operation reduces the required magnetic component size while maintaining electrical isolation functionality, thereby improving power density without compromising reliability.
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 reduces the overall cost and bulkiness of power electronics systems, increases power density, and enables fast and efficient battery charging and motor driving, achieving high efficiency and power density.
Implementation Method 1
having a respective transformer configured to provide electrical isolation
Implementation Method 2
convert the first three-phase AC signal into an output signal having a DC component at the output node for charging a battery
Implementation Method 3
convert DC power drawn from the battery to a second AC signal for energizing the electric motor
Data Source
AI summary
An apparatus includes a controller, a switching block, and a three-phase bidirectional AC/DC converter. The switching block has a first interface connected to a power grid, a second interface connected to an electric motor, and a third interface connected to the three-phase bidirectional AC/DC converter that includes first, second, and third single-phase AC/DC conversion modules, and which have inputs and outputs joined at an output node, and a respective transformer configured to provide electrical isolation. In a first mode of operation, the switching block connects the power grid to the AC/DC converter for charging a battery connected to the output node and disconnects the electric motor. In a second mode of operation, the switching block disconnects the power grid and connects the electric motor to the AC/DC converter which is controlled to convert DC power drawn from the battery to energize the electric motor.