Reserch On Bidirectional DC-DC Converter And Its Application On Energy Saving Elevator System

Load in elevator is a typical kind of potential energy load, which regenerates large amounts of electric energy during its reciprocation movement, showing great energy-saving space. At present, most elevators employ power resistance to burn off regeneration energy, producing tremendous waste. Though, some elevators employ energy feedback unit, new problems like harmonic pollution to the power grid follow. In recent years, a new energy-saving scheme of bidirectional DC-DC converter along with super capacitance is rising, which makes effective use of the common AC-DC-AC structure of elevator power supply and super capacitance’s characteristics. It can also acts as an emergency power supply device, and is an elevator energy-saving technology with great development potential.This paper firstly analyses the unified structure of energy-saving elevartor, builds up bi-directional DC-DC converter’s indexes, according to which the bidirectional full-bridge topology is seclected out among all kinds of DC-DC topologies. Improvements on practicability have also been made to solve some specific problems.Next, this paper employs double closed-loop control to the design, decompose covertor model into curent loop model based on discrete structure and voltage loop model based on state-space averaging method. Further more, controller scheme and parameters are designed, whice are tested under Simulink environment to verify their preliminary correctness.Lastly, experimental platform and testing shemes are designed to verify the feasibility. The platform consists of hardware and software parts. The former includes passive devices, main circuit, controller board and system power supply. The latter includes MCU program and CPLD program. Testing shemes include statical and transient response processes of both current loop and voltage loop. The result shows that this design can satisfiy the expectation and the requirment of elevator working condition, possess high practicability and reliability. At the same time, the result provides basis for future improvment.