(1) Descriptions with photos

(a) Prototype

At the preliminary stage, we attempted to produce a printed circuit board (PCB) manually. By using the DesignSpark software, we drafted a schematic diagram with the required components including the integrated circuit (IC), SPV1020, which was employed for nominal voltage step-up and acted as a boost converter. However, it was found that short-circuit was the main shortcoming for manual PCB production as routeing was not ideal and often closed to each other. This affected the expected output voltage under malfunction condition.

(b) Version 2

To solve the short-circuit problem, we decided to produce a new PCB by factory production. After accomplishing our circuit design, factory assisted producing a more accurate PCB with precise routeing. This could avoid the occurrence of short-circuit problem and enhance the efficiency with less noise created. Most significantly, with an oil-painted layer on the PCB surface, there is a provision of protection layer so as to prevent the deterioration of etching solution or conductive parts.

(c) Latest version

We have obtained an enhanced quality of the SPV1020 PCB. At next stage, we intended to carry out fine-tuning procedure to figure out the corresponding efficiency under different output voltages. As we needed to acquire the most suitable and ideal voltage value with the highest efficiency to fit for the targeted solar vehicle, testing had been conducted after enhancing the PCB circuit layout.

(2) The integrated circuit SPV1020:-

SPV1020 is a PWM mode DC-DC boost converter used to step-up voltage and applied in a solar vehicle. One of the key functions aims to achieve Maximum Power Point Tracking (MPPT) technique.

In order to maximise the energy transferred from the PV cell string to the DC bus (connected to the output of the converter) the converter embeds a logic running a Perturb & Observe MPPT algorithm based on the monitoring of the voltage and current supplied by the PV.

• Schematic wiring diagram showing the entire design circuit with SPV1020 chip and all components