Sampling and holding structure, controller, alternating current-to-direct current switching power supply and sampling method

Abstract

The invention provides a sampling and holding structure, a controller, an AC-to-DC switching power supply and a sampling method, the sampling and holding structure comprises a charging module, a discharging module, a control module and a sampling module, the discharging module comprises an energy storage element and a discharging unit, the charging module is used for charging the energy storage element, and the discharging unit is used for discharging the energy storage element. The sampling module is used for collecting voltage of a feedback end of a transformer auxiliary winding of the AC-DC switching power supply, the control module is used for sending a sampling signal to the sampling module at a set proportion of transformer secondary side degaussing time, and the set proportion is in direct proportion to a ratio of a charging current during charging of an energy storage element to a discharging current during discharging of the energy storage element. According to the invention, the sampling time of the period can be determined according to the demagnetization time of the period, and the sampling time is not influenced by the change and magnitude of the primary peak current of any period.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, and more particularly, to a sample-and-hold structure, a controller, an AC-to-DC switching power supply and a sampling method. Background technique [0002] Compared with the traditional secondary feedback switching power supply mechanism structure, the primary side feedback (PSR) mode AC-DC control technology has the biggest advantage in eliminating the isolation feedback device, which saves the space on the circuit board and reduces the It reduces the cost and improves the reliability of the system, so it is widely used in small and medium power chargers, adapters and LED drivers. [0003] figure 1 It is a structural block diagram of a primary-side feedback AC-DC power supply in the prior art. as attached figure 1 As shown, the primary-side feedback AC-DC driving power supply includes a rectifier bridge BR, an input capacitor Cin, a start-up resistor R4, a power supply recti...

AI Technical Summary

Problems solved by technology

Therefore, in the traditional primary-side feedback scheme, the adjacent cycle CS cannot change significantly. Otherwise, assuming that the Tons of the Nth cycle is 9us, the sampling time of the (N+1)th cycle is 6us, but if the (N+ 1) When CS becomes smaller in one cycle, Tons(N+1) will also become smaller in the same proportion. If you still sample at 6us at this time, the sampled voltage will change. In extreme cases, if the (N+1 ) cycle CS becomes smaller than 1 / 3, then Tons(N+1)<6us, at this time sampling at 6us, the degaussing is over, FB enters resonance, and the sampled voltage cannot reflect the output voltage at all size, the sampling error

That is to say, the traditional sampling scheme can only be applied to the situation where the CS of adjacent periods cannot change significantly

[0009] As people have higher and higher requirements on the power supply system, the performance of the primary side feedback system also needs to be further improved, especially when the load responds dynamically, the PSR system is required to quickly respond to the changing demand of the load. At this time, not only the PSR system is required The operating frequency of the system can change rapidly, and the peak value of CS is also required to change rapidly. That is, when the load suddenly becomes lighter, the peak value of CS in the next cycle needs to be reduced rapidly. On the contrary, when the load becomes heavy, the peak value of CS in the next cycle is required to increase rapidly. , such a fast response can enable the PSR system to obtain good dynamic response performance; since two adjacent periods of CS will change rapidly, the degaussing time will also change in the same proportion, the existing sampling method cannot meet the requirements of the adjacent period CS fast Requirements for quick response to changes

Images