One-cycle control for Buck inductor current based on BLDC control system

In order to make the Buck converter more compact, smaller capacitor is chosen in case of meeting the design requirement. This will cause the capacitor voltage to uplift in some cases. This paper firstly analyzes that during the commutation interval the parameters of traditional inner current loop controller are difficult to adapt to the effects of the uplifting capacitor voltage. So it is unable to maintain the stable operation of the control system. The current loop cannot follow the reference value, causing the inductor current to fall during commutation interval. So as to solve the problem of the control system caused by the uplifting capacitor voltage, to enhance the anti-disturbance, and to achieve the stability of inductor current all the time, this paper presents a one-cycle control algorithm for the inner current loop. The capacitor voltage is considered and the capacitor voltage input is added based on the traditional inner regulator. In the algorithm, the duty cycle of the Buck switch can be calculated accurately to maintain the stability of inductor current during commutation time. Finally, based on the stability of inductor current, this article quantitatively analyses the effect of the uplifting capacitor voltage for the motor phase current and deduces the suitable capacitance, which can make the phase current more closer to the ideal square waveform so that the control performance of the BLDC is enhanced.