On-Board Charger Temperature Sensing With Ambient Compensation
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Solution Overview
Problem
Existing temperature measurement circuits for vehicle-mounted charging devices of new energy vehicles suffer from inaccurate temperature detection, which can lead to fire safety hazards due to thermal energy mismanagement during high-power DC fast charging.
Innovation Solution
A temperature measurement circuit with multiple temperature sensors (first and second at connection terminals and a third in the housing) and an analog-to-digital conversion module, along with a microcontroller unit for signal correction and filtering, to accurately measure charging temperatures considering ambient influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature measurement circuit is added to monitor battery pack temperature, then battery safety and charging efficiency are improved, but device complexity and cost increase
Solution Approach 1:
The temperature measurement function is merged with the existing charging device by integrating the temperature measurement circuit into the charging control circuit. The circuit uses the existing charging current path and combines temperature sensing elements with the charging control logic, allowing dual functionality (charging and temperature monitoring) within a single integrated system, thereby avoiding additional independent hardware modules.
Solution Approach 2:
The charging device is designed to perform multiple functions: it provides charging current to the battery pack while simultaneously monitoring temperature through integrated sensing elements. The control circuit processes both charging control signals and temperature measurement signals, enabling the single device to handle both power delivery and safety monitoring tasks without requiring separate dedicated systems.
2Measurement precision
If high-precision temperature measurement is implemented, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The temperature measurement circuit utilizes the existing charging current itself as the measurement signal source. By monitoring the voltage drop across a known resistance element through which the charging current flows, the circuit derives temperature information directly from the charging process parameters. This self-service approach eliminates the need for separate external temperature sensors and complex signal conditioning circuits, achieving accurate temperature measurement while maintaining circuit simplicity.
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
Enhances the accuracy of temperature measurement, improving charging safety and efficiency by preventing misoperations and high temperatures in new energy vehicles.
Implementation Method 1
a voltage divider circuit including a first resistor and a second resistor, the voltage divider circuit being connected in series between the power supply voltage and ground
Data Source
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AI summary
A new energy vehicle, a vehicle-mounted charging device, a temperature measurement circuit, and a temperature measurement method. The circuit comprises: a first temperature sensor (TH1), which acquires a first analog quantity temperature signal of a positive electrode connection terminal; a second temperature sensor (TH2), which acquires a second analog quantity temperature signal of a negative electrode connection terminal; a third temperature sensor (TFH), which is provided in a housing of the vehicle-mounted charging device of the new energy vehicle and acquires an analog quantity ambient temperature signal of the vehicle-mounted charging device of the new energy vehicle; an analog-to-digital conversion module (10), which correspondingly converts the first analog quantity temperature signal, the second analog quantity temperature signal, and the analog quantity ambient temperature signal into a first digital quantity temperature signal, a second digital quantity temperature signal, and a digital quantity ambient temperature signal; and a micro-control unit (20), which corrects the first digital quantity temperature signal and the second digital quantity temperature signal according to the digital quantity ambient temperature signal. The accuracy of measuring the charging temperature of the vehicle-mounted charging device of the new energy vehicle can be improved.