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Switching power supply having separate AC and DC current sensing paths

A switching power supply, switching technology, applied in the direction of high-efficiency power electronic conversion, electrical components, regulating electrical variables, etc., can solve problems affecting the accuracy of work cycle control and other issues

Active Publication Date: 2015-03-25
ANALOG DEVICES INT UNLTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This adversely affects the duty cycle control accuracy and regulation of the output voltage Vo
In multiphase parallel converters where switching noise can couple among the phases, the problem can become much worse

Method used

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  • Switching power supply having separate AC and DC current sensing paths
  • Switching power supply having separate AC and DC current sensing paths
  • Switching power supply having separate AC and DC current sensing paths

Examples

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Embodiment Construction

[0035] exist Figure 4 to Figure 10 Of the various embodiments of the invention shown, only those aspects of the converter that differ from that of FIG. 1 are shown for the sake of simplicity. therefore, Figure 4 to Figure 10 The output terminal of the PWM comparator 50 is coupled to the switching circuit shown in Figure 1, the output terminal of the inductor L1 is connected to the output circuit of Figure 1, and the voltage feedback path for generating the control voltage Vc is the voltage shown in Figure 1 feedback path. Other suitable circuits may be used in place of the circuit shown in FIG. 1 in conjunction with the present invention.

[0036] Figure 4 A first embodiment of the invention using different RC circuits for the AC sensing path and the DC sensing path is described. Resistor R1 and capacitor C1 are connected in series across inductor L1. The resistor DCR represents the inductor winding DC resistance. In contrast to prior art Figure 2 (where the RC time co...

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Abstract

In a current mode controlled switching power supply, current through an inductor (L1) is sensed to determine when to turn off or on the switching transistors (86, 88), the inductor current (IL) having a higher frequency AC component and a lower frequency DC component. The AC current feedback path (AC PATH), sensing the ramping ripple current, is separate from the DC current path (DC PATH), sensing the lower frequency average current. Separating the current sensing paths allows the signal to noise ratio of the AC sense signal (Vsen(ac)) to be increased and allows the switching noise to be filtered from the DC sense signal (K*Vsen(dc)). The gain (K) of the DC sense signal is adjusted so that the DC sense signal (K*Vsen(dc)) has the proper proportion to the AC sense signal (Vsen(ac)). The AC sense signal (Vsen(ac)) and the DC sense signal (K*Vsen(dc)) are combined by a summing circuit (72). The composite sense signal (Sum) is applied to a PWM comparator (50) to control the duty cycle of the switch.

Description

technical field [0001] The present invention relates to DC / DC converters, and in particular, to sensing current in current mode controlled switching power supplies. Background technique [0002] Figure 1 illustrates one type of prior art current mode DC / DC switching power supply, also known as a current mode DC / DC converter. Many other converter configurations can also benefit from the present invention. The type of converter shown in Figure 1 is a peak current mode converter. [0003] Operation of the converter is conventional and described below. [0004] A clock (Clk) signal is applied to the set input of RS flip-flop 20 . [0005] The setting of RS flip-flop 20 produces a high signal at its Q output. In response, logic circuit 24 turns on transistor switch 26 and turns off synchronous rectifier switch 28 . Both switches can be MOSFETs or other transistors. A diode can replace the synchronous rectifier switch 28 . Logic circuit 24 ensures that switches 26 and 28 do...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M3/155
CPCY02B70/1466H02M3/1588H02M1/14H02M2001/0009H02M1/0009Y02B70/10
Inventor 张金东
Owner ANALOG DEVICES INT UNLTD