Transformerless On-Board EV Charging With Sensor-Based Switch Control
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Solution Overview
Problem
Electric vehicle charging systems that rely on transformers are costly, complex, and inefficient, leading to energy losses and requiring external charging stations, which complicates vehicle deployment and maintenance.
Innovation Solution
A transformerless on-board battery charging system using capacitors and resistors to convert AC power to DC power, incorporating a power factor correction and non-isolated stage for efficient charging, with sensors and a controller to manage voltage and current for reliable operation across various battery states of charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a transformer is used in the charging infrastructure, then voltage conversion efficiency is improved, but system cost, size, and complexity increase
Solution Approach 1:
The patent removes the transformer component from the charging system, extracting the voltage conversion function to an external charging station while keeping the vehicle-side charger simple and compact. This eliminates the complexity and size issues of onboard transformers while maintaining voltage conversion capability through the external station's infrastructure.
2Power
If a transformer is used in the charging infrastructure, then voltage conversion is achieved, but system size increases
Solution Approach 1:
The transformer is extracted from the vehicle's onboard charging system and placed in the external charging station. This allows the vehicle to have a compact, transformerless charging unit while the heavy voltage conversion equipment remains at the stationary charging infrastructure, significantly reducing the volume of the moving object.
3Weight of stationary object
If charging stations are located external to the vehicle, then transformer size is reduced, but charging convenience decreases
Solution Approach 1:
The onboard charging system is designed to work with universal charging standards and protocols, allowing the vehicle to charge at any compatible charging station regardless of location. This multi-functionality approach maintains convenience by enabling charging at diverse locations while keeping the onboard unit compact and lightweight.
4Device complexity
If transformerless configuration is used, then system cost and complexity are reduced, but power factor correction and filtering requirements increase
Solution Approach 1:
The patent introduces power factor correction circuits and filtering components as intermediary elements between the AC power source and the battery charging circuit. These intermediaries handle the power quality issues that would otherwise require complex transformer designs, enabling a simpler overall system architecture while maintaining proper power conversion and grid compatibility.
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 costs, size, and complexity, enabling onboard charging, improving efficiency, and allowing convenient charging without the need for external stations, while maintaining reliable operation with inconsistent grid power.
Implementation Method 1
Transformerless configurations use other components, such as capacitors and resistors, to convert AC power from the grid into DC power for charging the vehicle battery
Implementation Method 2
Transformerless configurations use other components, such as capacitors and resistors, to convert AC power from the grid into DC power for charging the vehicle battery
Implementation Method 3
a first sensor assembly configured to measure a voltage of the rechargeable battery, a second sensor assembly configured to measure a voltage of an input power line supplying power to the charging circuit from a power supply external to the vehicle, and a third sensor assembly configured to measure a current of the charging circuit
Data Source
AI summary
A transformerless charging system including a charging circuit including a first switch and a second switch, a first sensor assembly configured to measure a voltage of the battery, a second sensor assembly configured to measure a voltage of an input power line, and a third sensor assembly configured to measure a current of the charging circuit. An electronic processor is configured to receive a voltage of the battery, receive a voltage of the input power line, compare the voltage of the battery to the voltage of the input power line, and in response to the voltage of the input power line being greater than or approaching the voltage of the battery, turn off a PWM signal to the first switch, and with the PWM signal off, receive a current of the charging circuit and, in response to the current of the charging circuit being 0 Amps, open the second switch.