Current type control system and method for three-state step-down switching power supply

Abstract

The invention discloses a current type control system and method for a three-state step-down switching power supply. The method comprises the following steps that: a first upper power tube and a corresponding first lower power tube are arranged on a voltage source loop, and a second upper power tube and a corresponding second lower power tube are arranged between the first upper power tube and thefirst lower power tube; the working states of a peak current mode and a valley current mode are set; in the peak current mode, the first upper power tube is turned on when a first rising edge arrives, and the second upper power tube is turned on when a second rising edge arrives; in the valley current mode, the first lower power tube is turned on when the first rising edge arrives, and the secondlower power tube is turned on when the second rising edge arrives; and the conduction time of the power tubes is controlled by adopting PWM signals. The current control method of the three-state step-down switching power supply is realized. The control method has the advantages of faster transient response, smaller device electrical stress and smaller inductance size.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, in particular to a current-type three-state step-down switching power supply control system and method. Background technique [0002] Due to the application requirements of high power density power supply, compared with the traditional BUCK topology, the three-state step-down (3-level BUCK) switching power supply has smaller device electrical stress and smaller inductor size under the same input and output range and power application conditions. advantage, began to receive more attention and research. [0003] Such as figure 1 The topological structure of 3-level BUCK is shown. Compared with the traditional structure, power transistor T2, power transistor B2, and capacitor C2 are added. In order to obtain the minimum device electrical stress and the smallest inductor size, it is necessary to keep the voltage on C2 as the input half of the voltage. [0004] Through the theoreti...

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Problems solved by technology

[0004] Through the theoretical research of 3-level BUCK, it can be seen that the voltage-type pulse width mode (PWM) control is very simple, but it also has two shortcomings that are difficult to overcome: one is that it is difficult to improve the transient response, and the other is that it requires a more complicated loop control to keep the voltage on C2 constant at one-half of the input voltage

Since the current mode 3-level BUCK cannot work in pure peak current mode (PCM) or valley current mode (VCM) like the traditional BUCK, it needs to switch between PCM and VCM as the duty cycle changes, so the control is relatively difficult. Complicated, and relevant reports and studies are relatively rare at present

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