Design of Peak Current Mode Synchronous Buck DC-DC Converter

In this article, a design scheme of peak current mode synchronous buck DC-DC converter is proposed based on synchronous rectification technology. The specific design scheme of the DC-DC converter is described from the overall structure design of control circuit, key circuit design and slope compensation. At the same time, the whole circuit simulation analysis of the DC-DC converter shows that the DC-DC converter has high performance

DC/DC converters based on hybrid MMC for HVDC grid interconnection

This paper presents a multi-terminal high-power DC/DC converter configuration based on hybrid MMC topology with fault blocking capability for interconnecting HVDC systems. Its main functions include bidirectional power flow, step-up and step-down operation and fault isolation equivalent to a DC circuit breaker. By contrast to the conventional MMC based DC/DC converter, the proposed DC/DC converter with hybrid MMC configuration has the advantage of being able to block the DC/DC converter terminal connecting to faulty DC grid section, while continue operating the other terminals connected to healthy DC grid sections. The proposed DC/DC converter operation is analyzed and its control is described. Simulation results using Matlab/Simulink are presented to demonstrate the robust performance during dc fault conditions

AC voltage control of DC/DC converters based on modular multilevel converters in multi-terminal high-voltage direct current transmission systems

The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC) is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM) capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC) system incorporating a DC/DC converter, and the simulation results confirm its feasibility

Energy-efficient and Power-dense DC-DC Converters in Data Center and Electric Vehicle Applications Using Wide Bandgap Devices

The ever increasing demands in the energy conversion market propel power converters towards high efficiency and high power density. With fast development of data processing capability in the data center, the server will include more processors, memories, chipsets and hard drives than ever, which requires more efficient and compact power converters. Meanwhile, the energy-efficient and power-dense converters for the electric vehicle also result in longer driving range as well as more passengers and cargo capacities. DC-DC converters are indispensable power stages for both applications. In order to address the efficiency and density requirements of the DC-DC converters in these applications, several related research topics are discussed in this dissertation. For the DC-DC converter in the data center application, a LLC resonant converter based on the newly emerged GaN devices is developed to improve the efficiency over the traditional Si-based converter. The relationship between the critical device parameters and converter loss is established. A new perspective of extra winding loss due to the asymmetrical primary and secondary side current in LLC resonant converter is proposed. The extra winding loss is related to the critical device parameters as well. The GaN device benefits on device loss and transformer winding loss is analyzed. An improved LLC resonant converter design method considering the device loss and transformer winding loss is proposed. For the DC-DC converter in the electric vehicle application, an integrated DC-DC converter that combines the on-board charger DC-DC converter and drivetrain DC-DC converter is developed. The integrated DC-DC converter is considered to operate in different modes. The existing dual active bridge (DAB) DC-DC converter originally designed for the charger is proposed to operate in the drivetrain mode to improve the efficiency at the light load and high voltage step-up ratio conditions of the traditional drivetrain DC-DC converter. Design method and loss model are proposed for the integrated converter in the drivetrain mode. A scaled-down integrated DC-DC converter prototype is developed to verify the design and loss model

Improvement of speed response in four-phase DC–DC converter switching using two shunt voltage-source

This study proposes a technique that is able to improve the speed response of a four-phase DC–DC converter switching. The basic concept of the proposed technique is the inclusion of two shunt-connected voltage sources in series to the converter system. Using a higher input voltage to drive the load, a higher current per microsecond output system will be obtained and reverts to its nominal input upon obtaining desired references. Thus, the transient response observed when using this proposed technique is found to be much faster when compared to the conventional converter. Moreover, this technique is easily implemented as it requires only an additional voltage source, power switch, and power diode. The integrated model of the two shunt voltage-source in a four-phase DC–DC converter was simulated in MATLAB/Simulink and validated against the experimental results of a laboratory prototype, 600 W four-phase DC–DC converter. The novelty of this proposed technique is its ability to provide faster operations for critical loads applications, lower output capacitor and lower operating frequency

DC-DC Converter for Electric Vehicle

In this work, a DC-DC converter is designed for an electric vehicle. The DC-DC converter is designed to provide 500W with a 200-400V input and a 12-15V adjustable output. Electric vehicle sales are beginning to increase in popularity and the need for DC-DC converters to siphon power from the tractive system is not yet fully satisfied, especially for single-seater class vehicles. Additionally, improving performance in efficiency without sacrificing wide input voltage range can benefit future DC-DC converter designs. In the end, a forward active clamp DC-DC converter is designed and tested. Additionally, spreadsheet calculators, LTSpice simulations, and Matlab scripts were made to assist in work for the DC-DC

Protection System For the Energy Harvesting from Exercise Machines (EHFEM) Project

The goal of the Energy Harvesting from Exercise Machines (EHFEM) project seeks to harness the energy generated by people using exercise machines and deliver this energy to the electric grid [1]. The implementation consists of a protection system, DC-DC converter, and an inverter. This project involves redesigning the existing DC-DC input protection circuit and current limiter for the EHFEM project [2]. The DC-DC converter takes in the power from the exercise machines and converts it to a manageable voltage level for the inverter. Due to a problem where the inverter may overload the converter, a current limiter sets to limit the current between the two circuits [4]. The inverter demanding more current at a lower voltage than the DC-DC converter can provide causes this overload. The input protection circuit for the DC-DC converter presents another major component of the protection system. The DC-DC converter must operate within set input voltage and current parameters. Concurrent with this project, students Byung Yoo and Sheldon Chu have developed a new DC-DC converter design with an operational range of 6 V to 51 V [7]. This paper proposes a design for an overvoltage protection circuit to limit the input of Yoo’s and Chu’s DC-DC converter to within its operational range. The input protection circuit regulates the incoming voltage from the elliptical machine and filters out any high frequency transient responses with capacitive filtering to generate a smooth DC signal. The circuit also functions to divert excess voltage and current that accumulates during the Enphase Micro-inverter’s startup period where an open load appears across the DC-DC converter leading to an overvoltage level [3]. A current sense circuit ensures the output from the DC-DC converter to the inverter delivers only as much power as the inverter can convert [4]. The device maintains a minimal component count number and lacks any excessively large components permitting easy assembly and installation. The device operates with a minimal loss of energy and minimizes fabrication costs allowing for recuperation of initial production costs over 10 years of normal use

DC/DC converter

Tato práce se zabývá tranzistorovými měniči především čtyřkvadrantovým můstkem. Převážná část práce pojednává o budičích tranzistorů a možném způsobu řízení měniče. Součástí práce je i návrh řídící elektroniky a regulační struktury. V rámci této práce bude zároveň zkonstruováno zařízení, která bude dále sloužit jako učební pomůcka pro studenty.This project deals with transistorized converters in particular a four-quadrant bridge. The main part of project discusses the drivers of transistors and a possible way of controlling a converter. The proposal of control electronics and the regulation structure are involved in the second part. This project also includes a construction of an apparatus which will be used as a teaching material.

Power Stage Driving Schemes for Multilevel Converter

The disclosure is directed to an improved multilevel DC-DC converter, which is commonly used by electronic devices with subsystems that have different voltage needs. The improved DC-DC converter is more efficient and smaller than conventional converters