Several experimental results have been obtained to check this behavior in a synchronous rectifier buck converter. To show this behavior the control transfer function (GLnLc) has been deduced. Furthermore, the LnLc improves the stability of the DC-DC power supply modifying the open loop gain and phase as function of the load current steps. Also, it is shown that the features of the linear-nonlinear control fit with the ideal control requirements, doing it better than the most of solutions. In this paper, the ideal control requirements with respect to fast transient response are defined. This novel control optimizes the features of the conventional linear control in order to reduce the recovery time of the output voltage drop produced when a load current step occurs. Linear-nonlinear control (LnLc) was presented like a solution to improve the transient response in low output voltage DC-DC buck converters, used to feed last generation of microprocessors and DSPs. Experimental prototype is built to verify the feasibility and advantage of the new method. Instead, to detect the critical time instant when the inductor current equals the new load current, a practical extreme voltage detector is introduced to capture the output voltage peak/valley information. Thirdly, unlike previous work, the proposed voltage based CBC (V-CBC) controller does not require accurate current sensor or fast analog-to-digital converter (ADC). Second, due to the simplicity of this algorithm, a low cost microcontroller unit (MCU) based controller can be implemented to shorten the developing period for users. Also, this algorithm can be simply extended to adaptive voltage positioning (AVP) application. The hardware implementation only requires the output voltage information so that no extra sensing circuitry is needed compared with voltage mode controller. The final implementation does not require complex calculations and accurate knowledge of the output filter LC parameter. First, this paper presents a new derivation of practical charge balance equations based on simplified differential equations. In this paper, a low cost microcontroller based control method utilizing the concept of capacitor charge balance is presented to achieve a near-optimal transient response for Buck converters. Both digital and analog experimental prototypes are built to verify the feasibility and advantages of the new method. Third, this algorithm is simple to be implemented by either low-cost digital signal processing devices (such as microcontroller unit) or analog circuits. Second, the proposed voltage-based charge balance controller does not require accurate current sensor or fast analog-to-digital converter. The final algorithm does not require complex calculations and accurate knowledge of the output filter LC parameter. This deviation is applicable to both fast input voltage and load step transients. ![]() In this paper, a novel voltage-based charge balance control algorithm is presented, which is suitable for both digital and analog implementations for buck converter to achieve near-optimal dynamic performance. A comparison with a time-optimal controller shows that the introduced programmable-deviation system results in up to 1.9 times smaller voltage deviation while limiting component stress. The operation of the controller is verified both through simulations and experimentally, with a boost-based 12 to 48 V, 100-W prototype, operating at 100-kHz switching frequency. The controller implements a simple algorithm for setting up the inductor current and the output voltage peak/valley values during transients, based on the output current estimate, which is obtained through a self-tuning procedure. ![]() ![]() In the second phase, the voltage is gradually recovered. In the first phase, the inductor current is set in the proximity of its steady-state value, so that the initial transient-caused capacitor charging/discharging process is reversed. To recover from transients, the controller passes through two phases. This paper introduces a practical mixed-signal current programmed mode (CPM) controller that, compared to time-optimal solutions, provides a smaller deviation, lower current stress, and simpler controller implementation. In boost converters and other indirect energy transfer topologies, the fastest transient response usually does not coincide with the minimum possible output voltage deviation.
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