An electrostatic precipitator developed with smart high voltage DC power inverter

Abstract: This paper presents an electrostatic precipitator voltage inverter power supply. Briefly discusses the main structure of the power of the works of the main circuit and control circuit works. Brief description of the system software. Keywords: ESP; high-voltage inverter; intelligent Introduction With the increasing amount of industrial dust emissions, environmental pollution is more and more serious, especially in metallurgy, mining, building materials, chemical industry . As we all know, the application of electrostatic precipitators can effectively collect the dust, however, the conventional high voltage electrostatic precipitator device is bulky, heavy and inconvenient to use, therefore, reduce the size and weight of the high-voltage electrostatic dust removal device is particularly important. In recent years, along with the rapid development of power electronics technology, especially the new generation of power electronic devices such as IGBT, MOSFET application, high-frequency inverter technology becomes more mature, a variety of different types and characteristics of the circuit is widely used in DC / DC and DC / AC and other occasions. In this context, the design of a high-voltage power inverter instead of the conventional high-voltage power supply to achieve the purpose of reducing the size and weight of the high-voltage power supply unit has become possible, Grid tie inverter . The same time, its effect, the output characteristics and the cost is also higher than the conventional high-voltage power supply apparatus has a distinct advantage, the system efficiency has been improved to some extent. The system hardware design to the 1.1 power the main structure of Figure 1 shows a circuit diagram of the voltage inverter power supply, it mainly includes two parts of the main circuit and control circuit. The main circuit includes a power switch, power frequency rectifier, chopper, filters, IGBT bridge inverter, protection circuits, high frequency high voltage transformers, high frequency, high voltage silicon stack (high-frequency rectifier) ​​part. The control circuit includes the current, voltage, sparking rate sampling and its processing unit, PWM signal generator and the drive circuit, micro-controller, parameter input keyboard and a liquid crystal display, a communication interface and other parts. 1.2 the working mechanism of the main circuit main circuit works as shown in Figure 2, the power switch in the high-frequency inverter using IGBT (insulated gate bipolar transistor). It is set in one of the advantages of the MOSFET and the GTR new composite devices, power inverter , has a high input impedance of the MOSFET, available voltage drive and low, GTR-state power consumption. 2 AC voltage of the main circuit schematic diagram in Figure 2 by the rectifier - the chopper regulator - filtered DC voltage U1, U1 added to the full-bridge high frequency inverter. D1 ~ D4 power switches S1 ~ S4 reverse parallel, to bear the load reverse current protection switch tube. C1 ~ C4 and R3 ~ R6, and D5 ~~ D8 introduction is in order to avoid the excessive rate of voltage rise in off four switch tube and reduce turn-off losses of the tube. When the gate pulse signals alternately drive S1 and S4 or S2 and S3, an inverter main circuit of the DC voltage U1 is converted to the 20 kHz high frequency rectangular wave AC voltage to the high frequency high voltage transformer to the load, after boost rectifier filter ( electrostatic precipitator) power supply. Control S1, S4 and S2, S3 groups IGBT duty cycle, rectangular wave AC voltage can be obtained pulse width adjustable. The 1.3 control circuit working mechanism 1.3.1 microcontroller controller with self-diagnostics, and human-computer exchange-control functions for the entire power system, the power supply selection PHILIPS series microcontroller 80C552, is mainly responsible for the real-time monitoring and data communication with the host computer's task . When the precipitator at work state, the microcontroller on the one hand timed acquisition values ​​of current and voltage feedback, channel A / D converter to read into and control the amount of Uk on certain algorithm to the pulse width by the the microcontroller output control amount modulation controller, thereby changing the modulation pulse width; external characteristic can be achieved according to the user's needs change power, constant current, constant voltage, slow down, etc.. In addition, the microcontroller periodically to the power supply output current, output voltage spark rate information passed to the host computer, the fault information by a serial hair up crew, to warn, to receive control commands from the host computer at the same time to make their own into or out of work or change the working parameters. 1.3.2 Pulse Width Modulation controller pulse width modulation controller circuit shown in Figure 3, and its main function is to control the driver circuit to provide pulses to achieve PWM control. Its core is generating a PWM signal application specific integrated chip SG3525A. SG3525A voltage type PWM integrated controller, fewer external components, good performance, with external synchronization, soft start, the dead zone adjustment, undervoltage lockout, error amplifier, and turn off the output drive signal functions. Its internal structure, including a reference voltage source, undervoltage lockout circuit, sawtooth oscillator, error amplifier, and pulse width modulation comparator Part 5. MCU 2 system software design of the power supply module has a separate main program as well as with the host computer communication program, data collection routines. Due to space limitations, this article discusses only the main program and the communication software subroutine structure of the power module. The main program flow chart shown in Figure 4, the data communication subroutine flow chart shown in Figure 5. Power module software to perform the following functions: receiving data and instructions sent by the host computer; transfer data up crew; complete the real-time monitoring of the power output; various external characteristics of the control according to user needs. 3 experiments and analysis 3.1 the main inverter bridge PWM regulation impact on the efficiency of research and normative regulation determine the way shown in Figure 6, the power supply in the case of the same input voltage, the duty cycle of less than 50%, with the duty ratio increases, the efficiency is also increased; in the duty cycle at> 50%, as the duty cycle increases, the efficiency is reduced. Thus, if a wide range of duty cycle adjustment, will cause the power to enter the region of low efficiency, while the duty cycle is 40% to 70%, higher efficiency. This way by adjusting the duty cycle of the chopper circuit to control the DC bus voltage, the purpose of high efficiency can be achieved. 3.2 field experiment testing the experimental conditions: ESP plate area of ​​250m2, electrode spacing 150mm, duty cycle of 60%, the frequency of 18.6kHz. Results: Figure 7 is a correspondence relationship of the output voltage and input voltage, and Figure 8 is a correspondence relationship of the output current and input voltage. When the output voltage of 58kV (current 82mA) precipitator flashover occurred, to the design requirements. 4 Conclusion 1) through the main inverter bridge PWM regulator Efficiency Institute determined by the chopper circuit on the DC bus voltage regulation is feasible; 2) the power at a significantly reduced volume and weight also significantly reduced its energy utilization in terms of the more traditional power increased, the control of the precipitator is also more convenient than traditional power, while data communication and IPC, achieve remote control precipitators.