Santosh K. Singh

Boost derived hybrid converter: Problem analysis and solution

Generating DC and AC voltage from a single DC input, through single stage conversion is cardinal for nanogrid applications. A boost derived hybrid converter is one of the topology used for nanogrid application, which works well in continuous mode of operation rendering both the dc and ac load simultaneously. Despite of this converters successful performance in continuous conduction mode, undesirable results come in to picture in case discontinuous mode and standalone AC operation. This paper focusses on providing the solution for above mentioned problems to stabilise operation in both conditions thus ensuring reliable operation of the converter under wide load ranges.

Modified hybrid L-Z source inverter — A closed loop perspective

Dual output converter are proposed in different literature. These converters has potential to supply AC and DC load simultaneously. But standalone operation and DCM phenomenon presence is the problem of converter in initial proposals. However, both these problems are counteract by introduction of antiparallel switch in Modified hybrid L-ZSI(MHLZSI). With this modification, the control technique is changed and has to supply one more PWM pulse. In open loop control, it is easy to provide the control pulse and Moreover it does not regulate the output. This paper proposes the closed loop study of MHLZSI. State-space analysis is done with reference to both DC load and AC load to reach out at the final transfer function in terms of control to output. DC and AC voltage control is designed using PI control. Both the controller includes the current control and voltage control loop. The inclusion of current loop in the system, makes transient to damped out quickly. The controllers are evaluated based on 1) the DC and AC reference voltage tracking 2) DC and AC load disturbance rejection. The simulation analysis is presented to provide the conclusive results.

Extended buck-boost derived hybrid converter

Dua\ output hybrid converter supplying DC and AC loads simultaneously are gaining interest due to their compact size. This is due to single stage conversion that results in cost saving and offers decoupled control of both AC and DC output. Though hybrid converter derived from boost was reported, they were unable to supply lower DC output. The hybrid converter proposed in this paper is able to supply the buck and boost dc voltage together with AC voltage. This converter is named as Buck-Boost Derived Hybrid Converter (BBDHC). The steady state analysis of the converter is presented to derive the gain of the converter. Moreover, the converter is analysed in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) which are related to inductor current nature. It is found that the BBDHC is not suitable for wide load variation as it creates the high voltage ripple in DC and distorts the AC voltage. To override these issues, the a modified converter is presented. This modification leads to CCM of the converter. The operating mode pertaining to this is named as forced continuous mode(FCM). The theoretical analysis is validated by the simulation and experimental results.

Switched capacitor impedance matrix converter

Ultra sparse matrix converter(USMC) is a derived form of Indirect matrix converter(IMC) having less no of switches. Though it has unidirectional power flow capability it is very useful for specific applications such as wind energy systems, electrohydrostatic actuator, variable speed drives etc. However its main limitation is lower gain for which various control strategies and topological changes had been implemented. Unlike the previous propositions, the work in this paper is primarily focused on integration of impedance source converter within USMC to enhance gain, by preserving the advantages of USMC. The proposed topology is verified by the simulation and experimental results.

Modified Boost Derived Hybrid Converter: Redemption Using FCM

Boost-derived hybrid converter (BDHC) is a single-stage converter that produces both dc and ac output voltages. The operation of BDHC under continuous conduction mode is satisfactory. However, the nonzero discontinuous conduction mode (NZ-DCM) and standalone ac operation restrict the stable operation of the converter. To mitigate these limitations, modified BDHC (MBDHC) is proposed in this paper. The main idea behind these changes is to redeem NZ-DCM by forced continuous conduction mode (FCM). The adverse effect of NZ-DCM in a BDHC is analyzed in terms of ac output voltage total harmonic distortion, and dc output voltage ripple. This analysis is further extended for MBDHC to highlight the benefits of FCM. Moreover, for hybrid loads, the efficiency of MBDHC is compared with its counterpart BDHC and cascaded boost inverter.

Multiple PMSG fed Non-inverting buck-boost converter for HEVs

Presently, the Hybrid Electric Vehicle(HEV) industry is driven by the battery technology and its power management. For charging the batteries there is requirement of Permanent magnet synchronous generator (PMSG) and power converters. The authors in this paper are exploring the prospects of multiple/dual stator PMSG instead of single PMSG. The interconnection of multiple PMSGs using Matrix of switches create several voltage levels, enhancing the charging range of the batteries under variable speed operation of the vehicle. In particular, at low speed the charging of the battery depends on the size of the inductor of the Buck-boost converter. The interconnection permits the PMSGs to operate near rated full load, preserving the energy efficiency of the drive. In this work, the dc output voltage is regulated using Non-inverting buck-boost converter at 160V under 48-180V AC(around 70-240 volt DC) input voltage variation of the PMSGs, reducing the size and cost of the Power converter.

Sensorless control of induction motor using EKF: Analysis of parameter variation on EKF performance

This paper deals with the investigation of the Extended Kalman Filter (EKF) for sensorless indirect vector control of an induction motor. The prime focus is low speed operation, when the EKF somewhat presents erroneous results. The effectiveness of the EKF as a speed estimator under machine parameter variations - change in stator resistance, rotor resistance is assessed. Furthermore, the effect of the changes in the measurement co-variance and error covariance matrices have been discussed using simulation and experimental results. Finally under low speed operation a relation between the error covariance matrices and machine parameter variations, for performance improvement of the induction motor, is established.

Extended boost three phase matrix converter using switched capacitor topology having buck boost ability

Matrix converters became very popular over AC-DC-AC converters for AC to AC conversion because of their beauty having no dc link capacitor. The gain of these converter can be varied only in the range of 0–86.6% of input voltage. This restricts its operation in high voltage application and also in grid integration. To enhance the boosting capability beyond the earlier one, this paper implements a switched boost capacitor network in the fictitious dc link present in the converter. Moreover, this converter inherits the advantage of bidirectional power flow without additional demand of the switch. The proposed topology is verified by the simulation studies.

High gain buck-boost matrix converter

Boosting factor of power converter is a critical requirement for high voltage low power applications. There are many extended DC-DC converter topologies available for boosting output voltage beyond the traditional boost converters. However, for direct AC-AC conversion boosting factor of four can be achieved using single inductive element or impedance source network. Though higher boosting beyond this factor is achievable, extra switches are needed. This paper proposes a new approach of direct AC-AC conversion for higher boosting of output voltage, without adding extra switches to a recently proposed AC-AC converter. This was made possible by restricting positive inductor current both during positive and negative AC half cycles. Instead of single inductive element, switched inductive network is added to the AC-AC converter. Moreover, as this concept is implemented using six switch matrix converter, the commutation problem of a typical AC-AC converter is avoided.

Design and development of rapid prototype controlled PMSM drive

Rapid prototype controller is a very useful part in the process of analyzing a designed system. Its ability to figure out faults and quickly rectify them makes it quiet interesting. This paper focuses on interfacing the simulation model to the real time world, to develop signal conditioning circuits between high power load or intelligent power module (IPM) with the low power digital controller platform and finally developed a rapid prototype controller for PMSM drive. All the emulation of switching signals are done using MATLAB and code composer.