BOOST circuit for improving transient response and application method of BOOST circuit

Abstract

The invention provides a BOOST circuit for improving transient response and an application method of the BOOST circuit, the BOOST circuit comprises a BOOST converter for generating an output voltage higher than an input voltage, a current sampling module for generating a current detection signal, a switching device for controlling the on-off of a PWM modulation signal, and a control unit for generating a PWM modulation signal under the action of a reference voltage, a voltage feedback signal of an output voltage, a current detection signal and a slope compensation voltage and generating a modulation signal with a preset duty ratio in a set time period, and an output voltage slope sampling module for sampling the descending slope of the output voltage in the turn-off time of a switching device. According to the invention, the time for changing the inductive current to the final load current can be reduced, so that the transient response speed of BOOST is improved, and the stability of the system is ensured.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a BOOST circuit for improving transient response and an application method for the circuit. Background technique [0002] In recent years, with the rapid development of consumer electronics products, the load transient requirements for power supplies are getting higher and higher. The BOOST converter can realize the voltage increase output, and it is a very wide range of converters in practical applications. However, due to the influence of the right half-plane zero point of the traditional BOOST converter, its crossing frequency must be less than half of this zero point, so its bandwidth Not much, load transient response is slow. [0003] The invention application with the patent application number CN201510134253.2 discloses a BOOST circuit for improving transient response. In order to solve the transient response problem (only including light load to heavy load), whe...

AI Technical Summary

Problems solved by technology

It should be known that only when the load is less than a certain value can it work in PFM mode. When the load exceeds this value, the circuit will work in PWM intermittent mode. At this time, the load is not very large, and it also faces transient undershoot when switching to heavy load. problem, which is a problem that this patent cannot solve

[0007] (2) There will be problems in adding a predetermined large duty cycle. When the duty cycle is large, the heavy load current is not particularly large, which will cause the inductor current to overcharge, that is, too much energy is delivered to the output. , which will cause the output voltage to overshoot; when the duty cycle is too small, the rising speed of the inductor current will be very slow, and the output cannot get enough energy to undershoot, and the effect of greatly improving the transient undershoot cannot be achieved.

[0008] (3) at figure 1 and figure 2 In the middle, the speed of the load transient is not fast, and the heavy load of the jump is not large enough, so when the transient occurs, the output voltage is still rising during the period when LX is high. In practical applications, the speed of the load transient will be much faster, and the jump The variable overload can also be large, so the undershoot will be more serious than the picture

[0014] (1) The circuit design is relatively complicated, not only need to adjust the frequency and transconductance, but also need to detect the reverse flow current and reverse current count

[0015] (2) The negative feedback dynamic current generation circuit introduces the small signal into the loop while the large signal adjusts the frequency and transconductance, so its influence on the loop stability must be considered, which increases the difficulty of the loop design

[0020] Due to the influence of the right-half-plane zero point of the BOOST converter, the bandwidth of BOOST is limited to less than half of the right-half-plane zero point, so the rise and fall of Vea are very slow, which results in the process of transient load changes, such as Figure 5 and Image 6 , the change of the duty cycle is very slow, so the change of the inductor current is also very slow, the t1 time is very long, and the maximum undershoot and overshoot voltage are very large

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