Linear Control Approaches for DC-DC Power Converters
This chapter covers the topic of DC-DC power electronic converter control in continuous-conduction mode. It aims at presenting how converter averaged (low-frequency) behavior can be tailored by means of feedback control structures. There is no unique cont
- PDF / 1,989,020 Bytes
- 50 Pages / 439.37 x 666.142 pts Page_size
- 38 Downloads / 282 Views
Linear Control Approaches for DC-DC Power Converters
This chapter covers the topic of DC-DC power electronic converter control in continuous-conduction mode. It aims at presenting how converter averaged (low-frequency) behavior can be tailored by means of feedback control structures. There is no unique control paradigm that solves this problem. To this end, various control structures with different design methods that have become classical in control systems theory can be employed with a similar degree of efficiency. It is generally assumed that the obtained control input is applied to converter switches by using pulse-width modulation. This chapter aims at giving a comprehensive view of this topic without exhausting the entire range of control approaches dedicated to the subject. The chapter presents the main principles, the design procedures and provides some pertinent examples, ending with two case studies and a set of problems.
8.1
Linearized Averaged Models. Control Goals and Associated Design Methods
As seen before (Chap. 4), it is beneficial to describe the average behavior of a converter by means of a linearized model; it provides good insight on plant performance in terms of steady-state gains, bandwidth, damping and other dynamic effects (e.g., nonminimum-phase behavior). This allows a full assessment of converter (plant) properties leading to control loop design that ensures the achievement of a certain goal (Stefani 1996). The drawback of this modeling approach is the fact that these plants are nonlinear (Verghese et al. 1986). As it has already been discussed, their linearized models have coefficients whose values depend on one (or more) timevarying exogenous signals, i.e., they change with the actual operating point and so does the linear-controller-based closed-loop system (Philips and Franc¸ois 1981; Mitchell 1988; Kislovsky et al. 1991). Therefore, linear controllers suffer from lack of robustness with respect to load and input voltage mean values, which must be S. Bacha et al., Power Electronic Converters Modeling and Control: with Case Studies, 187 Advanced Textbooks in Control and Signal Processing, DOI 10.1007/978-1-4471-5478-5_8, © Springer-Verlag London 2014
188
8 Linear Control Approaches for DC-DC Power Converters
taken into account when one approaches worst-case design, gain scheduling linear-parameter-varying or other adaptive techniques (Lee et al. 1980; Shamma and Athans 1990; Morroni et al. 2009; Algreer et al. 2011). The main control goal in DC-DC converters may vary with the converter role, but, in general, the aim is to regulate/track either the output or the input converter voltage (with respect to the power flow), while meeting a set of imposed performance requirements. The control loop may be more complicated as the primary goal may generate subordinate objectives produced when other issues are revealed during modeling (e.g., stability aspects). Also, the chosen control structure may be hierarchically organized for tracking some internal variables in order to achieve ˚ st
Data Loading...
