An integrated kinetic energy recovery system for peak power transfer in 3-DOF mobile crane robot

Powering a robot is one of the biggest challenges in robot design, which is one of new technologies that will positively impact robotics. Flywheel is a kind of device for energy conversion and storage, which is known as electro-mechanical battery. In this paper, a kinetic energy recovery system (KERS) for rubber-tyred gantry (RTG) crane robot is explored, which is based on a surface-mounted permanent magnet synchronous motor (PMSM) with an integrated flywheel spinning at high speed. At first, the basic background of situation RTG crane robot is introduced, afterwards the KERS is discussed to show that it can be perfectly used to meet the peak energy requirements of crane during both acceleration and regenerative braking. Then, a typical structure of KERS is designed step by step. A saturated inductance is designed to reduce the total harmonic distortion (THD) and allow the withdrawal of a large amount of currents. Direct paralleling of two insulated gate bipolar transistor (IGBT) modules is developed with consideration of the power demand. Next, the operation of the integrated system including power electronics, sensors and digital signal processor (DSP) is explained. The algorithm regulates the operation of the pulse width modulation (PWM) converter is realized by proportional plus integral (PI) controllers for charging the flywheel with constant current and discharging under constant power. Finally, the feasibility of the proposed system is verified by simulation.