Beyond time-optimality: Energy-based control of augmented buck converters for near ideal load transient response

Dynamic physical limits of a phase-shifted full bridge circuit for power supply of Magnetic Resonance Imaging gradient amplifiers

“…Many studies have been performed to improve the dynamic performance of DC-DC circuits [3][4][5][6][7][8][9][10][11][12][13]. The transient response is improved obviously by utilizing a time-optimal control for Buck converters [3][4][5].…”

“…The transient response is improved obviously by utilizing a time-optimal control for Buck converters [3][4][5]. Also for the Buck, a capacitor charge balanced control method is proposed in [6] to achieve the optimal transient response; by implementing two separate control strategies for both steady and dynamic states, the overall transient performance is improved to a nearly optimal response [7]; the fast load transient response of a synchronous buck converter is analyzed to minimize the cost and size of the output filter [8]; an auxiliary circuit is added to supply an extra energy path overcoming the slew rate limit of the output inductor and obtaining a faster response than the time-optimal control [9]; a capacitor current feed-forward controller is presented in [10]. In [11] and [12] for Buck and PSFB circuits separately, the natural switching surface is employed to achieve the optimal transient response.…”

Multiphase current controlled buck converter with energy recycling Output Impedance Correction Circuit (OICC): Adaptive Voltage Positioning (AVP) and Dynamic Voltage Scaling (DVS) application

“…The second possibility to reduce the output capacitor is to introduce an additional energy path to compensate the charge unbalance of the output capacitor [9]- [22], consequently reducing the transient time and output voltage deviation. Doing so, during the steady-state operation the system has high efficiency because the main low-bandwidth converter is designed to operate at moderate switching frequency, whereas the dynamic behavior is determined by the high-bandwidth auxiliary energy path, during the load-step transients.…”

“…Doing so, during the steady-state operation the system has high efficiency because the main low-bandwidth converter is designed to operate at moderate switching frequency, whereas the dynamic behavior is determined by the high-bandwidth auxiliary energy path, during the load-step transients. The auxiliary energy path can be implemented as a resistive path ( [9], [10]), as a Linear regulator, LR, ( [11]- [13], [19], [20]), or as a switching converter ( [14]- [18], [21], [22]). The first two implementations provide faster response, at the expense of increasing losses during the transient.…”

“…In addition, advance features, such as Dynamic Voltage Scaling (DVS) and Adaptive Voltage Positioning (AVP), impose opposite trends on the output capacitor design: for load steps, big capacitor is favorable, while for the output voltage reference step, smaller capacitor is favorable. Therefore, the ongoing research trend is directed to improve the dynamic response of the VRM while reducing the size of the output capacitor by means of either improving the controller [3]- [8], or by introducing an additional energy path to compensate the charge perturbation of the output capacitor [9]- [22].…”