The design and field programmable gate array implementation of a single-input fuzzy (SIF) proportionalintegral-derivative (PID) control scheme applied to DC-DC buck converters are presented. The SIF logic reduces the number of fuzzy rules and therefore the hardware resource occupancy without control property degradation compared with the double-input fuzzy (DIF) controller, which is realised by transforming the two-dimension rule tables into onedimension rule vectors using signed distance method and genetic algorithm. The adopted signed distance method requires the two-dimension rule tables to be of Toeplitz structure, which is realised by establishing the inference rules through analysing the system response curve. The fuzzy logic regulates the PID parameters based on the conditions of the power converters. As a result, the SIF-PID controller is superior to the conventional PID controller and is similar to DIF-PID controller in terms of the control performance. The proposed controller has been validated with simulation and experimental results.
Bifurcation and chaos in high-frequency peak current mode Buck converter working in continuous conduction mode (CCM) are studied in this paper. First of all, the two-dimensional discrete mapping model is established. Next, reference current at the period-doubling point and the border of inductor current are derived. Then, the bifurcation diagrams are drawn with the aid of MATLAB. Meanwhile, circuit simulations are executed with PSIM, and time domain waveforms as well as phase portraits in i L -v C plane are plotted with MATLAB on the basis of simulation data. After that, we construct the Jacobian matrix and analyze the stability of the system based on the roots of characteristic equations. Finally, the validity of theoretical analysis has been verified by circuit testing. The simulation and experimental results show that, with the increase of reference current I ref , the corresponding switching frequency f is approaching to low-frequency stage continuously when the period-doubling bifurcation happens, leading to the converter tending to be unstable. With the increase of f , the corresponding I ref decreases when the period-doubling bifurcation occurs, indicating the stable working range of the system becomes smaller.
A single-input fuzzy PID (SIF-PID) controller is proposed in this paper to improve the dynamic performance of dc-dc buck converter. The fuzzy logic adjusts the three parameters of PID controller adaptively by detecting the output voltage. Establishment of double-input rule table with Toeplitz structure is presented by analysising the system response curve. One-dimension rule vectors are derived based on the slope λ of the parallel diagonal lines in rule table to reduce the computational burden. The genetic algorithm is utilized to optimize the coefficient λ to guarantee the simplified rule vectors are equivalent to the original rule table in terms of control performance. Effectiveness of the proposed controller is validated by simulation results.
On the basis of the conventional PID control algorithm, a modified adaptive PID (MA-PID) control algorithm is presented to improve the steady-state and dynamic performance of closed-loop systems. The proposed method has a straightforward structure without excessively increasing the complexity and cost. It can adaptively adjust the values of the control parameters (K p , K i and K d ) by following a new control law. Simulation results show that the line transient response of the MA-PID is better than that of the adaptive digital PID because the differential coefficient K d is introduced to changes. In addition, experimental results based on a FPGA indicate that the MA-PID control algorithm reduces the recovery time by 62.5% in response to a 1V line transient, 50% in response to a 500mA load transient, and 23.6% in response to a steady-state deviation, when compared with the conventional PID control algorithm.
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