Research On Constant Frequency Hysteresis Control Of Active Filter Based On Optimal Space Vector

Active power filter (APF) is an effective means to eliminate harmonics in the powernetwork. The control effect of APF is decided by the detection and control technology ofharmonic current, and the latter is researched in this paper. There is much different in thecurrent tracking accuracy, speed of response, switching frequency, their loss and many otheraspects in different current control technology. These aspects of the active power filter haveimpacts in compensation effect and there will be restrictions on operating efficiency andwidespread use level of APF. This article studies APF constant frequency hysteresis currentcontrol method based on the optimal space vector, and in parallel three-phase three-wireactive power filter topologies as an example, study the control process in the followingaspects:1. For APF error current in the SVPWM switching signal timing, this paper analyzedcontinuous and discontinuous modulation, and the error current of two kinds of modulation.And then calculated the two modulation error current and compared their merits with differentvoltage vector species at the same switching frequency. At last, this paper proposed optimaland suboptimal discontinuous modulation control methods, and resulted in conclusion thatdiscontinuous modulation had the advantage of continuous modulation in a reasonable DCvoltage utilization ratio.2. This paper improvd several aspects for alternating current fixed-frequency hysteresiscontrol method, including the improvements about the error current phase control in thefixed-frequency hysteretic control, that can be achieved with discontinuous switchingmodulation, and the the phase current switching control on control area, that can achievesuboptimal discontinuous modulation control of switching signal. These improvements makefurther improve in constant frequency hysteresis control in error current tracking accuracy,and finally proposed the improved the optimal constant frequency hysteresis current controlmethod based on space vector.3. Taked detailed analysis of the implementation process about the improved optimalconstant frequency hysteresis current control method based on space vector, and used PSCAD/EMTDC power transient simulation software to verify the feasibility of this method, and compared with other fixed-frequency hysteretic control method about the error current. At lastmade the conclusion that this constant frequency hysteresis control has higher accuracy inerror current.