EMI Reduction and Output Ripple Improvement of Switching DC-DC Converters with Linear Swept Frequency Modulation

This paper proposes a new EMI reduction and automatic ripple cancellation technique about the ripple-controlled converter with the ripple injection and Constant-On Time (COT) method. The ripple-controlled converters have no stable clock and it is difficult to reduce the EMI noise by shaking the operating frequency. The new method of EMI reduction is that the COT pulse width is modulated by the triangular signal so that the operating frequency is modulated and the spectrum peak level of the clock frequency is greatly reduced. But the output voltage ripple is much increased because of the change of the duty ratio of the operating frequency. The increaced ripple is canceled by adding the modulation signal to the ripple injection circuit. Moreover stabiliztion of the operating frequency on Discontinuous Conduction Mode (DCM) is reported. The operating frequency falls down on DCM mode in the COT converters. To stabilize the operating frequency, cheking the operating period is fedback to control the COT pulse width

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“…K is calculated 0.54 [A/MHz] from Eq. (3)(4)(5)(6) and is derived 0.49 [A/MHz] from the simulation result in Fig. 3-1, whose error rate is +10%.…”

Section: Operating Frequency Fop On Dcmmentioning

confidence: 99%

Frequency Stabilization and EMI Noise Reduction of COT Method Ripple-Controlled Switching Converters with Output Voltage Ripple Cancellation

Kobori

Sun

Tran

et al. 2020

AEF

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“…On the other hand, the typical slope of the SAW signal is shown in equation (2)(3)(4)(5)(6). To cancel the duty change of the clock pulse, the slope will be corrected to change the slope by modulating the current of the SAW generator (Isaw).…”

Section: Correct Ripple Voc [Mv] Conductance Gm [µS]mentioning

confidence: 99%

“…Also in order to reduce the increased output ripple, we have investigated to modulate the control signal with reverse phase. For the ripple-controlled converter [6]~ [9] with the ripple injection method, we have investigated to modify the phase of the control signal. For cancelling the increased ripple, we have investigated to modify the additional current to the ripple injection circuit.…”

Section: Introductionmentioning

confidence: 99%

EMI Noise Reduction of DC-DC Switching Converters with Automatic Output Ripple Cancellation

Kobori

Sun

Tran

et al. 2020

AEF

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This paper proposes new EMI reduction technologies and automatic output voltage ripple cancellation method for the PWM buck converter with voltage-mode or current-mode and the ripple-controlled converters. Genenrally, modfying the clock frequeny is effective to reduce the EMI noise, but it may increase the output ripple substantially. We have developed techniques to cancel the increased ripple by modifying the slope of the saw-tooth signal or current of the ripple injection circuit. The EMI spectrum of the operating frequency is reduced by more than 15dB and the modified large ripple is canceled to the stable level.

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“…[1,2,3,4,5,6,7,8,9,10,11]. In switch mode, power devices work in on-off state with the control of a high frequency (∼kHz or ∼MHz) signal [4,10,12,13,14,15,16,17,18,19]. So, the switch mode current source facilitates high conversion efficiency and small volume.…”

Section: Introductionmentioning

confidence: 99%

“…So, the switch mode current source facilitates high conversion efficiency and small volume. However, ripple, electromagnetic interference (EMI) and relatively complex control circuit are drawbacks of switching power supply [18,19]. Whereas, in linear mode, power devices usually work in constant current state with the control of feedback signal [20,21,22,23,24].…”

Section: Introductionmentioning

confidence: 99%

Linear current module adaptive to wide operating voltage range based on automatic series/parallel conversion

Wang

Fu³

2020

IEICE Electron. Express

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A new method based on adaptive series/parallel conversion to realize linear current output in a wide operating voltage range is presented in this paper. According to the load state, a switch array is employed to perform adaptive series/parallel conversion control on load segments and corresponding constant current branches to ensure constant current in each load segment and constant power of the total load in wide operating voltage range. The proposed design combines the advantages of switch mode current source and linear constant current source. The correctness and feasibility of the proposed method are verified by experiments of a LED driver.

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EMI Reduction and Output Ripple Improvement of Switching DC-DC Converters with Linear Swept Frequency Modulation

Cited by 9 publications

References 2 publications

Frequency Stabilization and EMI Noise Reduction of COT Method Ripple-Controlled Switching Converters with Output Voltage Ripple Cancellation

Frequency Stabilization and EMI Noise Reduction of COT Method Ripple-Controlled Switching Converters with Output Voltage Ripple Cancellation

EMI Noise Reduction of DC-DC Switching Converters with Automatic Output Ripple Cancellation

Linear current module adaptive to wide operating voltage range based on automatic series/parallel conversion

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