Multi-layers PCB used to improve the cooling of current transducer

Thermal modelling for current transducer is very important to define the current measurement range, to optimise the selection and thermal distribution of each components (parts stress analysis) and to set the environmental thermal limitations. While those limitations are influenced by different factors, this paper highlight the importance of a correct modelling of the PCB, including the selected design of the pattern and number of PCB layers. Indeed, it directly affects the maximum temperature of the power transistors which generally sets the thermal limitation of the transducer. The modelling has been made with a 3D finite element software. The advantage is the flexibility to change the parameters (e.g. primary current, ambient temperature, AC or DC behaviour, material, design) and to get quickly the new thermal distribution, allowing a fine tuning of the design before any hardware prototype is made. Nevertheless, such approach is only effective if the calculation results are accurate and reliable, and many practical factors and assumptions make it generally difficult. In this paper, simulations results are validated by hardware measurements.