Control circuit and control method of Boost-Buck converter and Boost-Buck converter employing same

Abstract

The invention discloses a control circuit and control method of a Boost-Buck converter. The control method comprises the following steps of sampling an induction current, and accordingly generating a current sampling signal; controlling to receive the current sampling signal in a rise time interval of the induction current in each switching period; maintaining the maximum value of the current sampling signal to generate a sampling signal at the moment when the induction current is rise to an inductance current peak until the current switching period is finished; limiting the inductance current peak according to a second reference signal representing information of the maximum value of the inductance current, so that the induction current cannot be excessively fluctuated, and the fluctuation of an output voltage also can be relatively reduced; and meanwhile, adjusting the duty ratio of a switching device by a feedback control loop according to real-time error information between a compensation signal and a voltage signal representing the inductance current. Therefore, the dynamic response speed of the system is relatively high, the time required for restoring to a stable state again is shortened, the dynamic response speed of the system is increased, and the stability and the reliability of the system are improved.

Description

technical field [0001] The invention relates to the field of switching power supplies, and more specifically, to a control circuit and a control method for a buck-boost converter. Background technique [0002] Buck-boost converters, such as four-switch buck-boost converters, are widely used in the fields of electric power, communications, and electronic instruments due to their advantages of in-phase input and output, low switching loss, and adjustable output voltage. The optimal control strategy of the switch has also become a hotspot of current research. [0003] refer to Figure 1A , shows the block diagram of a buck-boost converter. The buck-boost converter includes two parts, a power stage circuit 11 and a control and drive circuit 12; wherein, the power stage circuit 11 receives the input voltage Vin, and generates a stable output voltage Vout at the output terminal to drive the load; the control and drive circuit 12 to generate the corresponding control and drive si...

AI Technical Summary

Problems solved by technology

[0009] In view of this, the object of the present invention is to provide a novel control method and control circuit of a buck-boost converter to solve the problem of large output voltage fluctuations and frequency jumps in the prior art when operating mode switching and light load conditions , slow dynamic response, low efficiency, and technical problems such as audio noise

Images