Soft start control method of power supply and device thereof

Abstract

The invention relates to a soft start control method of a power supply and a device thereof. The soft start control method is characterized in that after the power supply is started, an open loop is used for carrying out soft start; when output voltage of the power supply reaches a set value, a switch control mode is started, and under the switch control mode, an analog-digital converter converts the output voltage of the power supply into digital signals which are used as basis of whether to switch to closed loop control and adjust the output voltage; and a bit length utilization rate of the analog-digital converter is improved by utilizing the technology, smooth output voltage waveforms can be guaranteed, the maximum or the minimum overshoot under the switching mode can be avoided to the largest degree at the same time, and namely, transient response is restrained effectively.

Description

technical field [0001] The present invention relates to a power supply, in particular to a soft start control method and device for the power supply. Background technique [0002] The so-called soft start refers to the process in which the output voltage (Vo) of the power supply rises from zero to the steady-state reference value (Vo, ref) after the power supply is started. The ideal output voltage curve is as follows: Image 6 shown. General soft start can be divided into open loop (Open loop) and closed loop (Closed loop) control. [0003] see Figure 7 Shown is a block diagram of an existing switching power supply system, mainly a switching power supply 70 converts the input DC power (DC INPUT POWER) and transmits it to the load, and its output voltage passes through an analog-to-digital converter ( ADC) 71, a digital compensator 72 and a digital pulse width modulator (DPWM) 73 perform feedback control on the switching power supply 70 to adjust its output voltage; where...

AI Technical Summary

Problems solved by technology

[0009] However, the closed-loop control is not without disadvantages: under the full closed-loop control, the conversion value range of the analog-to-digital converter must include the full start-up part, which makes the resolution insufficient in steady-state operation and produces a limit cycle (Limit cycle)

For the problem of insufficient resolution, an analog-to-digital converter with a higher bit length can be selected, but it will inevitably increase the cost and power loss

[0010] From the above, it can be seen that open-loop or closed-loop control for soft start has its own advantages and disadvantages. Therefore, no matter whether you choose open-loop or closed-loop control, you must take care of one thing and lose the other, and cannot cover everything. Therefore, how to combine the advantages of the two can avoid the disadvantages of the two. Weaknesses that need to be further reviewed and workable solutions sought

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