EV Inverter Charging Using Stator Windings as a Boost Inductor
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Solution Overview
Problem
Electric vehicles with traction batteries having higher nominal voltages than legacy battery chargers face challenges in charging, as the existing chargers cannot provide the necessary higher output voltage.
Innovation Solution
The system includes an AC electric motor with a stator having multiple stator windings and an inverter that can switch to provide alternating current propulsive energy and step up the voltage from a charging input using at least one stator winding as a boost inductor, allowing charging even with chargers having lower output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If legacy battery chargers with lower output voltage are used, then charging infrastructure compatibility is maintained, but they cannot charge traction batteries with higher nominal voltage
Solution Approach 1:
The inverter is designed to perform multiple functions: it can operate as a standard inverter for motor propulsion and as a voltage step-up converter for charging. By using the inverter's switching capability and stator windings as boost inductors, the system can accept lower voltage from legacy chargers and convert it to the higher voltage required by the traction battery, making the vehicle compatible with existing charging infrastructure while maintaining the ability to charge high-voltage batteries
Solution Approach 2:
The system dynamically changes the operating parameters of the inverter based on the charging mode. During charging operation, the inverter switches to a voltage step-up configuration where the stator windings function as boost inductors, transforming the voltage level from the charger's lower output voltage to the battery's required higher voltage. This parameter transformation enables compatibility between legacy chargers and modern high-voltage batteries
2Adaptability or versatility
If a voltage step-up mechanism is added to enable charging with lower-voltage chargers, then charging compatibility is improved, but system complexity increases
Solution Approach 1:
The inverter serves dual purposes: motor propulsion during vehicle operation and voltage step-up conversion during charging. By utilizing the existing inverter hardware (switching devices and stator windings) for both functions, the system avoids adding separate dedicated voltage conversion equipment, thereby limiting the increase in system complexity while achieving charging compatibility
Solution Approach 2:
The inverter uses its own stator windings as boost inductors for voltage step-up conversion during charging. This self-service approach eliminates the need for external boost converters or additional inductive components, as the motor's own windings are repurposed for the voltage transformation function, thereby reducing overall system complexity
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 enables efficient charging of high-voltage traction batteries using lower-voltage chargers, ensuring compatibility and effective energy transfer, and can perform two-phase interleaved step-up conversion for enhanced efficiency.
Implementation Method 1
using at least one of the stator windings as a boost inductor, switch the inverter to step up a voltage at a charging input coupled to the inverter
Data Source
AI summary
A motor vehicle includes an AC (alternating current) electric motor having a stator with a plurality of stator windings, a rechargeable source of stored electrical energy, and an inverter coupled to the rechargeable source of stored electrical energy and to the AC electric motor. The system also includes one or more controllers collectively programmed to switch the inverter to provide alternating current propulsive energy from the rechargeable source of stored electrical energy to the plurality of stator windings and, using at least one of the stator windings as a boost inductor, switch the inverter to step up a voltage at a charging input coupled to the inverter to charge the rechargeable source of stored electrical energy.