The Technology And Application Of Elevator Energy Feedback

In the face of energy shortages and the urgent need of energy-saving of elevators, according to the current inverter technology, we designed an energy feedback system with AVR microcontroller at the core, which is based on technical innovation and the idea of energy saving. The system can convert the energy stored in the capacitor of the inverter to alternating current, which is sent back to grid. Thereby,we achieve the purpose of energy-saving, and because the system does not have heating power resistors, the operating environment of it improved greatly.In this article, the elevator energy feedback system designed consists of hardware and control software. The hardware circuit mainly includes power inverter circuit, network synchronization circuit, voltage,current detection control circuitry, main control circuit and logic protection control circuit. The power inverter circuit adopts advanced IPM intelligent module and isolated interface circuits. The network synchronization circuit makes each switching device in the three phase voltage inverter circuit work 120°, and at any time, there are only two switching devices works in the inverter circuit. The network synchronization circuit not only works safe and reliable, also it can achieve the purpose of outputing the voltage to synchronize with the grid. This essay designs the voltage and current detection circuit by hysteresis circuit, whose control is simple and accurate. The voltage and current detection circuit realizes the protection functions of under-voltage,over-voltage and over-current. The core of the main control circuit is ATmega128, which has rich external interrupt sources and 16-bit timer / counter with prescaler and comparable features. On the one hand, ATmega128 can generate high precision PWM wave according to control algorithm, on the other hand, ATmega128 use grid-based synchronous signal and IPM fault signal to control the whole energy feedback system to make it proceed safe and effective. This article designs the logic protection control circuit by programmable logic device CPLD, which performs some logic arithmetic operations among the grid-synchronous signal, current,voltage control signal, IPM fault signal and the output signal of the microcontroller. The logical arithmetic operations ensure the process of the inverter works smooth. Since CPLD can integrate all of the logical operators, it reduces system latency and makes the design of system easy.In this paper, based on the inverter control technology, we proposed a new SVPWM algorithm based on the modulation function. The algorithm in the elevator control system has advantages of high DC voltage utilization, low harmonic content of output waveform and is easy to compute.The design of hardware circuit and the realization of software algorithms in this article are analyzed by the corresponding simulation software firstly. Then, we make experimental circuit of the system and set up the experimental platform. Finally, we debug the software and test the hardware, and give key experimental waveforms which improve the energe feedback system produce better results. The experimental results show that the hardware circuit designed is reliable and the software implements the planned functions. The energy feedback systems of the elevator can feed back energy safely and effectively, minimize harmonic contents of the output waveform, and reduce harmonic pollution and reactive power pollution to grid.