Overview of model-free control of switching power supplies
Model-free control of switching power supplies enables switching power supplies to develop in the direction of digitalization, intelligence, and multi-function. This undoubtedly improves the performance and reliability of switching power supplies. However, since the switching power supply itself is a nonlinear object, it is quite difficult to establish an accurate model, and approximate processing is often used. Moreover, the power supply system and load changes are uncertain, so it is often difficult to use the above analog or digital PID control method. The parameters of the PID regulator change accordingly, and the control effect is not ideal. The recently developed model-free control is a promising control method. It does not rely on the mathematical model of the controlled object and integrates modeling and control. This is very suitable for some complex and variable systems or systems with uncertain structures that are difficult to describe with accurate mathematical models. It improves the performance of switching power supplies. The control system not only meets the high performance and high reliability requirements of the switching power supply.
With the rapid development of power electronics technology, power electronic equipment is increasingly closely related to people's work and life, and electronic equipment is inseparable from reliable power supply. Switching power supply is a power supply that uses modern power electronics technology to control the turn-on and turn-off time ratio of switching transistors to maintain a stable output voltage. Switching power supplies are generally composed of pulse width modulation (pWM) control ICs and MOSFETs. Most of the switching power supply control parts are designed and work according to analog signals. The disadvantage is that the anti-interference ability is very poor. Due to the rapid development of computer control technology, digital signal processing and control have shown obvious advantages: easy computer processing and control, greatly improved design flexibility, convenient software debugging, etc., pID control has emerged.
In control law design, it is generally necessary to establish a mathematical model of the dynamic system. The classical method requires that this mathematical model must be established in advance and at least its structure must be determined in advance. And the more accurate the model, the better. The design of the model-free control law breaks through the restriction of the control law requiring that the mathematical model be established as accurately as possible in advance.
Our modeling procedure is accompanied by feedback control. The initial mathematical model can be inaccurate, but it must ensure that the designed control law has a certain degree of convergence. The model-free control law we designed is to control while modeling. After obtaining new observation data, we can then model again. Control. If this continues, the mathematical model obtained each time will become increasingly accurate, and the performance of the control law will also be improved. We call this procedure the integration procedure of real-time modeling and feedback control.
