Predictive control of buck converter using nonlinear output capacitor current programming

Abstract

A predictive control of buck converter to achieve fast transient response is presented. The methodology is based on using the output capacitor current and instantaneous output voltage to predict the output voltage at the end and mid of a switching cycle to determine the state of the main switch. Two switching criteria, one for switching on and one for switching off the main switch, will be formulated. The operating principles of the control method and all possible cases in the operation will be discussed. The proposed control method has been verified with experimental results of a 50W, 12V/5V buck converter prototype. The controller is realized by analogue devices. The steady-state and transient response to large-signal disturbances will be discussed.

Derivation of a nonlinear output capacitor current programming technique applicable for a buck converter operating in CCM and DCM

“…Only equation (20) will be satisfied over a switching cycle, thus, 2 / 1 T t > and T t ≤ 2 . For the converter operating in CCM, the values of t 1 and t 2 are determined as [9]. For the converter operating in DCM, the values of t 1 and t 2 are determined as follows.…”

“…A nonlinear output capacitor current programming technique that tackles the above drawbacks and retains the fast dynamic control of converter has been proposed in [9]. It has several advantages: fixed frequency operation and no hysteresis band.…”

“…However, it is only applicable for a buck converter operating in continuous conduction mode (CCM). This paper extends the concept of [9] that two switching criteria for a buck converter operating in both CCM and discontinuous conduction mode (DCM) will be derived. A 25W, 12V/5V prototype has been built and evaluated.…”

Investigation of the steady-state and dynamic characteristics of a buck converter with nonlinear output capacitor current programming

“…Although some fixed-frequency boundary control methods have been proposed, they require an additional switching frequency control loop [8]. A control method [10] that tackles the above drawbacks and retains the advantages of the time-domain dynamic control technique is proposed. It does not require adding a hysteresis band and is in constant switching frequency operation.…”