2019 Project Competition at Electrical Engineering Department, NIU

2019 Project Competition at the Electrical Engineering Department, National Ilan University

E-Drive for a Bicycle​

We won first place!!!!!!

In this competition, a two-stage circuit has been proposed and tested. The project’s goal is to realize high efficiency to extend the battery’s lifetime and cruising distance while achieving high power density so that the circuit is small and light-weight. The first stage is a multi-phase interleaved buck converter to convert battery power to a constant DC bus voltage. The second stage is a three-phase inverter that uses the DC bus voltage as its input to drive the BLDC motor that drives the E-bike. The buck converter stage utilizes GaN switches to achieve higher switching frequency and high power density. Also, a unique control algorithm is used to balance the current through the four phases of the buck converter. This first prototype was fully built and tested. It achieved a maximum efficiency at full load of 96.6% and its power density is 7.32 W/cm3.

Preliminary Specifications:

  • Input: 48-V battery
  • Output Power: 500-W
  • Input: 48V DC nominal from specified 9Ah battery pack.
  • Output: 3-phase BLDC motor drive; Vout: 36V; Pout: 500W; variable speed.
  • Power Density: >1.5 W/cm3 without the fan.
  • Converter temperature rises < 40°C with 500W @ 25°C Ambient Temperature.
  • The peak efficiency is 96.6%.


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