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Optimization Design Of An ASIC For Type A Residual Current Circuit Breakers

Posted on:2017-12-07Degree:MasterType:Thesis
Country:ChinaCandidate:A L LiFull Text:PDF
GTID:2348330482472573Subject:Electronic Science and Technology
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With economic development and social improvement, electrical equipment tends to be large-scale and complex. Awareness of energy-saving and environmental protection has been deeply rooted in human mind. Rectifiers, frequency inverters and switching power supplies are widely used in the power grid, so more and more non-sinusoidal residual leakage currents and harmonic currents turn up. As a result, nuisance tripping or failed tripping is more and more likely to happen for traditional type AC residual current circuit breakers, leading to huge property damage and casualties. Thus, type AC residual current circuit breakers cannot meet the market demand. Type A residual current circuit breakers, which reacts rapidly and exactly in the face of AC and non-sinusoidal residual leakage currents, get huge popularization.In order to satisfy the requirements of market applications, this thesis mainly tries to decrease the large variation of residual currents' tripping threshold for type A residual current circuit breakers. The main work and innovation include:1. The ASIC chip dedicated for Type A residual current circuit breakers is analyzed in detail in its operating principle, system structure and working process, as well as the variation of residual currents'tripping threshold brought about by the chip's different circuit modules. According to the market's demands and performance requirements, a systematic solution is proposed.2. An optimization design is implemented for the ASIC chip's analog section. The mismatches in integrated circuit are studied, including systematic offset and random offset. Methods to reduce the input offset voltage of an amplifier are introduced, and a chopper stabilization amplifier is accomplished. The factors that result in oscillating frequency's PVT variation for oscillators are researched, and various compensation techniques are given out. At last, an innovative PVT compensation scheme for ring oscillator with a tail current is presented.3. An optimization design is implemented for the ASIC chip's digital section. A detailed analysis of the characteristics of leakage currents generated by current transformer is carried out. The digital algorithm to realize distinguishment of type A residual currents gets optimazied design, and the corresponding realization circuit is completed.4. The chip is implemented in CSMC 0.5?m CMOS process. Circuit design, simulation, layout design, tape-out and the final test are completed. Test results of the ASIC chip for Type A RCCBs show that type AC residual current's tripping value deviates to 26mA, and its process variation is-3.5%?+3.5%. As for the other kinds of residual currents, their tripping currents' threshold is 22mA, and process variation is -5.5%-+4.5%. Thus, the design specification about process variation is achieved but for type AC residual current. As for tripping currents'variation caused by supply voltage and temperature, the specifications are all satisfied except for type AC's supply voltage variation (-0.76%?-1.50%).
Keywords/Search Tags:Type A residual current circuit breakers, mismatches in integrated circuit, PVT compensated ring oscillator, type A residual currents' judgment algorithm, decrease the tripping currents' variation for type A RCCBs
PDF Full Text Request
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