Mitigation of EMI in CCM DC-DC Converters with Grouped Clocking Technique

PurposeThe purpose of this paper is to propose a mathematical model for voltage super-lift dc-dc power converter in continuous conduction mode (CCM). Using the presented mathematical model, the analysis of dynamics of power stage for voltage super-lift dc-dc power converter can be performed.Design/methodology/approachThe proposed method is based on the average state space model using the state equations of the dc-dc power converter. In the proposed method, the converter is represented as a set of differential equations derived for each switching state of the power switch in terms of inductor current and capacitor voltage. The proposed method describes the dynamic behaviour of the system. The controller is designed to meet performance requirement of the system such as to maintain the dynamics such as stability, steady-state accuracy and the speed of response of the system. Using the obtained model, the analysis of dynamic response of the voltage super-lift dc-dc power converter can be performed.FindingsThe converter is modelled and verified using conventional circuit analysis method employing state-space averaging technique, and their corresponding transfer function is also derived. The dynamics of the converter is investigated using frequency response characteristics obtained using MATLAB programming environment. In addition, to improve the stability of the converter, proportional-integral controller is designed using Ziegler–Nichols tuning rules, and the effect of the compensator in the plant is also investigated.Originality/valueThe proposed method can be used for analysing the dynamics of power stage for voltage super-lift DC-DC power converter.

This brief proposes an improved averaged small-signal model of pulse-width modulated dc-dc power converters operated in continuous-conduction mode, which includes a resistance that corresponds to the switching power loss. Through this model, the switching power loss can be incorporated into existing averaged small-signal dynamic models. The proposed approach is based on the principle of conservation of energy. The expressions for the equivalent switching-loss resistance for the basic converter topologies are derived. The improved dc and small-signal models of the switching network are given. A boost dc-dc converter is considered as an example. The effect of the switching-loss resistance on the small-signal control-to-output transfer function is shown. Experimental results are given and the theoretical predictions have been validated.

The boost converter operates either in discontinuous conduction mode (DCM) or in continuous conduction mode (CCM). The operation mode is determined by the duty ratio, load and parameters of the boost converter. The plant model in DCM and CCM are different in the frequency domain response. Therefore, it will be difficult to design a controller with stable operation and fast transient response for both modes. Moreover, the boost converter will be unstable between DCM and CCM. In this paper, the proposed control strategy can transit between DCM and CCM seamlessly by adding a mode detector, the boost converter can be automatically operated by selecting of control loop in both operation modes. The proposed controller still has a voltage control loop in DCM and current/voltage control loops in CCM. Each controller is designed by considering the stability and response time. The proposed mode detector will be explained with a frequency domain analysis. Due to the wide range operation capability of the proposed control strategy, the proposed control strategy is suitable in the fuel cell portable applications. In addition, smooth operation of the converter will also be beneficial to the fuel cell stack reliability. A 20 W boost converter prototype is used to verify the performance of the proposed control scheme.

The voltage lift technique is a popular method that is widely applied in electronic circuit design. This paper introduces implemental methods of the voltage lift technique based on the SEPIC and Cuk converters. A series of novel dc-dc converter topologies are constructed. Compared with the SEPIC and Cuk prototypes, these converters can perform positive to positive/negative/double output dc-dc voltage increasing conversion with higher voltage transfer gains, high power density, high efficiency and cheap topology in simple structures. They are different from other existing dc-dc step-up converters and possess obvious advantages. The theoretical analysis in the continuous conduction mode is given in detail. Both the simulation and experimental results are provided to verify the proposed topologies.

This paper investigates the energy transfer modes of the quasi-Z-source (qZS) DC-DC converter, and accordingly, presents the critical inductor design considerations. The energy transfer modes of the qZS DC-DC converter are generally classified into the continuous conduction mode (CCM) and discontinuous conduction mode (DCM) when considering whether the inductor current reaches zero. In addition, the CCM can be further divided into a complete inductor supply mode (CISM) and an incomplete inductor supply mode (IISM) when comparing the minimum inductor current and the maximum load current. The critical inductance under the CISM, IISM, and DCM for the qZS DC-DC converter is derived in this paper within a specific range of the loading and input voltages in this paper. The capacitor voltage ripple in the impedance network and the output voltage ripple in these energy transfer modes are also obtained. Both simulations and experimental tests are presented to validate the theoretical analysis.

An approach for minimizing worst-case spectral components of certain circuit waveforms in DC-DC converters is developed. The approach is based on a programmed pulse-width-modulation (PWM) method for harmonic reduction. It is demonstrated that it is possible to precompute an optimal sequence of subperiods to minimize worst-case spectral components. These spectral components can also be effectively reduced by the introduction of high-index random frequency modulation

This paper proposes a high step-up dc-dc converter based on Cockcroft-Walton (CW) voltage multiplier without step-up transformer. Providing high step-up rate, the proposed converter is quite suitable for applying to low-input level dc generation systems. The proposed converter improves the impractical operation of the conventional boost dc-dc converter at high duty ratio due to non-ideal characteristics of the circuit components, such as the equivalent series resistance of the inductor. For easy design, a commercial average-current-control continuous conduction mode (CCM) integrated circuit (ICE1PCS01) and a complex programmable logic device (CPLD) LC4256V are used to implement the control strategy of the proposed converter. A modified switching function, which is built in CPLD, controls the switches to generate an alternating source to the CW voltage multiplier. Under CCM operation, the output voltage ripple of the proposed converter can be limited by the flexibly adjustable frequency. A 200W laboratory prototype is built for test and the experimental results demonstrate the validity of the proposed converter.

The DC-DC converter is a crucial component in power electronics technology, serving as the foundation for many complex converter structures and is widely used in various applications that require different voltage levels. Based on the continuity of inductance current and different sources of load resistance power supply, Boost DC-DC converters have different operating modes, including continuous conduction mode (CCM) and discontinuous conduction mode (DCM). CCM can be further classified into complete inductor supply mode (CCM-CISM) and incomplete inductor supply mode (CCM-IISM). Based on theoretical analysis and derivation of critical inductance expressions for CCM-CISM and CCM-CISM, several typical operating modes were simulated and verified by means of MATLAB/Simulink.

It is the design criteria of driving LEDs at constant current and keeping the input current’s harmonics low, attaining a high power factor, and maximizing efficiency. For low power general purpose lighting buck converter can be chosen for simplicity and reduced cost. It is a difficult to improve power quality parameter like, the THD (total harmonic distortion) and power factor of ac mains. In the proposed topology, the operation for high power factor and low THD at the AC mains’ input is accomplished through buck converter operation in both discontinuous conduction mode (DCM) and continuous conduction mode (CCM) with a suitable control circuit. This paper assures constant current in both cases for suitable design of control circuit. Over voltage protection has been incorporated. To validate the LED driver circuit, simulation studies are carried out.

Using Multivariate Polynomials to Obtain DC-DC Converter Voltage Gain

The presented work exhibits high gain and increased efficiency for DC-DC converter. Additionally, this topology significantly improves the voltage conversion ratio when compared with other DC-DC converters reported recently. The non-existence of high frequency transformer ensures compactness and low cost and henceforth, it is apt for clean energy applications. The analysis of the high gain converter in steady state is carried out in continuous conduction mode (CCM). Initially, the proposed converter performance is analyzed using MATLAB/Simulink platform and prototype of the same with a power rating of 200 V, 100 W is built and tested. The reliability and robustness of the converter is perceived from the experimental results and peak efficiency achieved is around 93%.

In DC microgrids, a high-gain DC-DC converter based on the coupled inductor technology or the voltage multiplier cell (VMC) is generally used to obtain a higher output voltage. To simplify the design and obtain higher voltage gain, this paper has improved a non-isolated DC-DC converter without modules such as voltage multiplier cell (VMC) and coupled inductors. The gain of this kind of converter can reach about 25 times. The converter is theoretically deduced in continuous conduction mode (CCM) and the voltage stress are calculated. Finally, a set of input parameters of 20V and output of 300V was selected for simulation to verify the correctness of the proposed converter.

A non-inverted dual output buck-boost DC-DC converter is proposed in this paper for solar fed water pumping employing SRM (Switched Reluctance Motor) drive. The utilized DC-DC converter provides a symmetrical dual output supply to the split DC capacitors of a mid-point converter and balanced voltages across DC link capacitors. The continuous conduction mode (CCM) operation of dual output buck-boost converter reduced current and voltage stress on converter components and nullifies the EMI (electromagnetic interference) problem. The electronic commutation of SRM converter enhances the efficiency of water pumping system by lowering the switching losses. A P&O (Perturbation and Observe) algorithm for highest power tracing is used in the present system to regulate the duty cycle of DC-DC converter and to ensure the efficient operation of solar array arrangement. The appropriate execution of MPPT controller eases the soft starting of proposed drive for water pumping by restricting the large starting inrush current in windings of SRM. From the analysis of simulated performance of proposed system, it is revealed that the system operates efficiently at all possible environmental conditions.

This paper presents a DC-DC converter with wide-range negative output for active-matrix organic light-emitting diode (AMOLED). The generated negative voltage Vout is connected to the negative terminal of the organic light-emitting diode (OLED), and the luminous brightness is adjusted by changing the value of Vout. The negative output voltage of the DC-DC converter is regulated by a Buck–Boost topology structure with a dual-loop control (DLC) system composed of a voltage loop and a current loop. The proposed compensatory peak-current-sensing technique (PCST) and switch MOSFETs adaptive drive technique (ADT) successfully support the implementation of the converter topology and enable the converter to work in continuous conduction mode (CCM). In addition, with the DLC system, the converter can guarantee a negative output voltage that enables both a fast transient response such as excellent load/line regulation, and a small output voltage ripple of the pulse width modulation (PWM) control. The proposed chip is implemented in a 0.18 μm CMOS process that operates at an operating frequency of 2 MHz with a maximum efficiency of 85.82%. The output voltage ripple is 1.5 mV at typical loading of Vout=−4 V and Iout=100 mA.

Dual Randomized Pulse Width Modulation (DRPWM) is renowned for its better effectiveness than Simple Randomized Pulse Width Modulation (SRPWM) in reducing conducted Electro-Magnetic Interferences (EMI) in power converters. However, the introduction of low-frequency ripples into the output voltage by dual randomization has not yet been addressed; this effect is investigated in this paper for a buck converter operating in both the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM). First, the modulating principle is presented. Then, a general analytical expression for power spectral density (PSD) of the input current is derived and validated for the proposed DRPWM scheme for both the CCM and DCM. A comparison of the PSDs of the input current for all RPWM schemes in both the CCM and DCM shows the PSD spreading effectiveness of the dual scheme as compared to simple schemes. Finally, the low-frequency output ripple is analysed using the PSD of output voltage. The results reveal that the output voltage ripple is affected by all the randomized schemes in both the CCM and the DCM. Also, the dual scheme (RCFM-RPPM) introduces the highest low-frequency voltage ripple, especially in the CCM and for low duty cycles. In DCM, the RPPM scheme gives the lowest voltage ripple, while the RCFM scheme gives the lowest voltage ripple in the CCM. The results are confirmed by both theory and simulations.