Electromechanical energy conversion between a DC motor and a capacitor bank: a compreensive and low-cost experiment

In this work, we present an experiment that illustrates an electromechanical energy conversion between a DC motor and electrolytic capacitors. The DC motor is coupled to a rigid disk and initially powered by a voltage supply, then the power supply is disconnected, and the electrical machine is connected to an electric diode in series with a capacitor bank. The stored charge in the capacitor bank demonstrates that the device, previously working as a DC motor, starts operating as an electric generator. The proposed experiment can be used to discuss the physical model of DC motor, induced electromotive forces, diode characteristic curve, and dynamics of the capacitors. We present a comprehensive mathematical model for the capacitor charging dynamics and characterize the relevant circuit parameters. Computational simulations are performed and predicted final capacitor voltages and electromechanical conversion efficiencies are compared with the experimental data. The overall agreement between the proposed model and experimental data is very good.

Keywords:
Electric circuits; motors; electromechanical conversion