| Uncontrolled diode-rectifiers are usually adopted as the primary stage of genera arc welding inverter power source,and followed by a big smoothing capacitor.These circuits lead to distorted waveforms of input current in AC side. Arc welding power source input current distortion on the power grid caused serious pollution, and reduces the power factor of the equipment itself, thus increasing the capacity of equipment with the requirements of power grid, resulting in waste of power grid capacity. Therefore, harmonic suppression and power factor correction has become the development of arc welding inverter power source must should be addressed.Conventional arc welding power sourec use single-chip as the controller,but it's computing capacity for digital signal processing is not strong enough,become increasingly inadequate to meet the arc digital control of welding power source requirements.With the DSP chip prices continue to decline,more and more arc welding power source use the DSP chip which has a higher speed of operation instead of single-chip.A DSP chip used for the control of the primary stage of controlled diode-rectifiers and the IGBT is very hard, and unable to meet the requirements of digital signal processing. as the DSP chip a sharp drop in prices, dual-DSP used in arc welding power supply with Active Power Factor Correction function is a good choice: Higher performance, lower cost.The topic chose two TI's DSP chips TMS320LF2407A,the two chips constitute a master-slave system. TMS320LF2407A is designed specifically for motion control, and its internal hardware structure is very suitable for rectifier and inverter control, fast digital signal processing and rich peripherals,it's also include SVPWM mashine,it can build space vector waveform automaticlly without software action.Put it into the APFC control of power supply,the user's work will be greatly simplification.In addition,the ability of DSP for fast data process and inside integration equipment, can cut user's design cost to least.It's inside 10 bit A/D converter is also suitable for voltage and current sampling and computating. The SPI module Can facilitate the realization of dual-DSP real-time fast communication.Inorder to make arc welding power source achieve high efficiency,the coordination of the dual-DSP is the key, so,how can we ensure effective inter-communication is the most important in this article to resolve the problem. TMS320LF2407A chip a powerful SPI modules, the largest degree of transmission can be sent tens of megabits per second, fully meet the requirements of the subject. SPI simple hardware interface module , host and slave only four data lines need to be able to communications, software, programming is relatively more easily, work stable and reliable.In order to prevent the transmission data errors caused by unusual work of arc welding power source, Use of CRC Cyclic Redundancy Check Code, this method is more accurate and safe method of error detection, can identify a lot of transmission errors, and coding is simple, very low probability of miscarriage of justice. Issues in the use of CRC-16 method, the probability can be detected 216-1/216 errors, when the error occurred in the use of re-issued by way of response to re-send the raw data, and then to CRC check, until the correct date. The use of DSP system to achieve CRC error check in the process is ease of integration and ease of use, the use of C language compilation and implementation of the hybrid coding have good efficiency and real-time, and occupying less system resources.Arc welding power source work in the high-voltage, high current and high-frequency magnetic field,the DSP chip is vulnerable to a variety of outside interference, in order to avoid a series of serious consequences,such as,run disorders, disorders of internal guidelines, resulting in erroneous operation procedures; control symptoms state failure; RAM data to be modified,and even this will lead to more serious system crash. Therefore, in DSP applications, the software fully exploit the anti-interference ability and to take certain measures can inhibit the impact of interference to a minimum. The main issue of the use of redundant instructions, procedures to run surveillance system (WD) and software traps inhibit three software tools, software practice has proved an effective anti-interference technology to ensure the normal operation of the procedure.Topics also designed a human-computer interaction systems, we designed a 4×1 scan-style keyboard with a 128×64 dot matrix LCD screen, very good communications system for the completion of the control and real-time data display and easy to use.Ultimately, the author would be very good in all the above together into functional modules, to build a set of dual-DSP real-time information collection and communication systems for the follow-up dual-DSP-based study of arc welding inverter power source has laid a solid foundation.
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