In the paper the problem of smoothing peak loads in a frequency-controlled tram electric drive is considered. The article shows that during the starting operation modes of urban transport in weak DC contact power supply, a significant voltage drops can occur, which can negatively affect on the operation of other consumers. The authors propose to supplement the system of frequency-controlled electric drive with an additional power source. The additional power source includes a block of supercapacitors and a bidirectional DC/DC converter with its own automatic control system. The article discusses several options of control algorithms for solving the problem of limiting the peak power, consumed from the contact power supply during the starting modes of urban transport electric drive. After the analysis, a variant of the energy storage system was proposed, which limits the energy consumption of the electric drive from the contact line at a given level, while providing the necessary technological operation modes of tram electric drive. Block diagrams and control algorithms are given. In conclusion, the simulation results of the frequency-controlled tram electric drive with energy storage system are presented, which show the effectiveness of the developed control algorithms.

In the paper the research results of digital single-loop control system for supercapacitor energy storage as an element of hybrid power supply of frequency-controlled alternating current electrical drive are presented. The integration of a supercapacitor energy storage device into the electric drive is made by using the bidirectional DC-to-DC converter. The description of laboratory testbench setup, structure and mathematical model of digital single-loop automatic control system are given. Mathematical simulation and experimental evaluation of the digital control system performance have been carried out.

The article considers the existing methods for calculating the capacitance for energy storage device. Two approaches to choose the capacitance of a supercapacitor for smoothing peak loads are described, energy diagrams and equations are given for both cases. In the approach proposed by the authors, the storage capacity is selected, based on the peak current setpoint, which is consumed from the contact DC power supply. The dependence of the capacitance from peak current is given. An example for determining the capacitance of a supercapacitor module for a frequency-controlled tram electric drive is described. The cost of energy storage devices is calculated. The methods of mathematical modeling confirm the high accuracy of capacitance calculation and illustrate the proposed approach to smoothing peak loads. It is shown that the capacitance of the supercapacitor in the second case is 9 times less, from which it follows that second method has advantages in the mass and price of energy storage device.

This article provides an overview of the use of supercapacitor energy storage systems in adjustable AC drives for various purposes. The structures of the power section of combined (hybrid) power supplies for vehicle electric drives (hybrid electric vehicles and public transport vehicles) and general-purpose electric drives of an industrial grade (cranes, freight, and passenger lifts) are given. This review focuses on the problems inherent in conventional solutions adopted in the implementation of the power section, as well as the effect that can be obtained when using supercapacitor energy storage systems in controlled electric drives. The topologies of reversible DC/DC converters for supercapacitor energy storage devices are considered with a comparative assessment of their advantages and disadvantages, as well as their areas of application. This paper provides an overview of the structures of automatic control systems for supercapacitor energy storage devices. The composition and principles of regulating variables, the types of regulators used, and the criteria for setting regulation systems are analysed.

In the article the review of using the supercapacitor energy storage systems in frequency-controlled alternating current electric drives for various purposes are given. The article discusses various variants for connecting the electric energy storage devices based on batteries and supercapacitors to electric drive systems. The structures of the power part of combined (hybrid) power supplies for electric drives of vehicles (hybrid electric vehicles and urban transport), general industrial electric drives (cranes, freight and passenger elevators) are given. The review focuses attention on the problems, that are typical for traditional solutions for the power part of electric drive systems, as well as on the effect, which can be obtained, when supercapacitor energy storage systems are used in frequency-controlled electric drives.

An indirect method and procedure for determining the local heat transfer coefficient in experimental studies on the intensity of heat transfer at a gas–surface interface is described. The article provides an overview of modern approaches and technical devices for determining the heat flux or friction stresses on surfaces in the study of thermophysical processes. The proposed method uses a constant-temperature hot-wire anemometer and a sensor with a thread sensitive element fixed on the surface of a fluoroplastic substrate. A substrate with the sensor’s sensitive element was mounted flush with the wall of the investigated pipeline. This method is based on the Kutateladze–Leontiev approach (the laws of friction and heat transfer) and the hydrodynamic analogy of heat transfer (the Reynolds analogy): this is an assumption about the unity of momentum and heat transfer in a turbulent flow, which establishes a quantitative relationship between friction stresses on the heat exchange surface and heat transfer through this surface. The article presents a method for determining the speed of the developed measuring system. An example of a successful application of the proposed method in relation to the study of thermomechanical processes in the gas exchange systems of reciprocating internal combustion engines is described.

The paper deals with the problem of the voltage stabilization in the DC link of a frequency converter with an PWM inverter, which is part of AC drive with a frequency method of speed control. To stabilize the voltage in the DC link, energy storage technology is used, which is implemented with using an energy storage device based on supercapacitors, which is connected to the DC link by means of bi-directional DC-DC converter. The work uses the concept of stabilizing the DC bus voltage by compensating the PWM inverter load current with the external current of the energy storage device. The energy storage device is equipped with a single-loop tracking current control system. The current control system is based on the combined control method. The aim of the work is to improve the accuracy of voltage stabilization in the DC link of frequency converter. The sensitivity of the DC link voltage to various disturbing factors is investigated. The theoretical analysis of the error coefficient of the current control system is carried out. The simulation of the electric drive is carried out without and taking into account the discreteness of the DC-DC converter. The research results can be useful in the development of supercapacitor energy storage control systems for various applications.

In the article the main approaches to calculation the nominal capacity of the supercapacitor module of energy storage for variable frequency asynchronous electric drives are discussed. A brief overview of the known procedures for calculating the nominal capacity of the module, both without taking into account and taking into account the power losses in the elements of the electric drive, is given. An example of determining the capacity of a supercapacitor module for a frequency-controlled asynchronous electric drive with a variable cyclic load is described. Energy expressions are given. The problem of accounting for losses in the elements of an electric drive is discussed. Variants of approximate calculation of power losses and the idea of an iterative procedure for a more accurate calculation of capacity are proposed.

In the paper a frequency-controlled electric drive with an energy storage system, based on supercapacitors, is considered. The description of the research object is given. The structure of the mathematical model of an asynchronous electric drive with an energy storage device is presented. The main task of investigation of electric drive under operation with a cyclic variable load, which combines reactive and active static torque components, is formulated. A method for determining the maximum acceptable heating load of an induction motor is presented. The simulation results of the motor operating modes under control both with a constant rotor flux and optimal control with minimum stator current are presented. Based on the typical tachogram and load diagram for hoisting mechanisms, the resource of a squirrel-cage induction motor, according to the criterion of the acceptable from the heating point of view motor torque, was detected. A comparative analysis of the motor power losses with a cyclic variable load of an electric drive at controls with a constant flux linkage and with minimum stator current was carried out. Main conclusions about the energy efficiency of using the control law with minimum stator current and its influence on the dynamics of energy storage system as part of an electric drive, operating in modes with a cyclic variable load, is given.

in the article an energy efficient electric drive system with PWM rectifier is considered. The article describes a detailed mathematical description of the mathematical model for a PWM rectifier with a direct power control (DPC) system. The paper also discusses a PWM rectifier control algorithm based on direct power control. In the article the functional and structural diagrams of the automatic control system for PWM rectifier, as well as the results of mathematical simulation are shown. The simulation results of an electric drive with a PWM rectifier show the correct work and high performance of the direct power control system. The developed mathematical model allows to significantly reduce the simulation time for complex electric drive systems in comparison with models, based on the using the SimPowerSystem library from the Simulink application.

The paper gives a comparative analysis of crane electric drive systems with a common DC link. The work compares electric drive system with a diode rectifier and brake chopper and a system with an energy storage device. The latter includes a block of supercapacitors and bidirectional DC-DC converter and it is connected to a common DC link. The structure of the control system for energy storage device is discussed, and the features of systems simulation with a common DC link are also considered. The simulation results, that clearly demonstrate the possibilities of energy saving in a system with supercapacitors, are presented. In conclusion, on the example of a gantry crane with a hoisting capacity of 8 tons, an calculation of the technical and economic efficiency of using the energy storage system in a crane electric drive is made. With using the methodology for determining a net present value, the payback period for additional capital investments is given.

The article discusses the comparison of energy-saving electric drive systems with an PWM rectifier and an energy storage device based on supercapacitors. A brief description of the control systems of the active rectifier and energy storage device is given. With using mathematical modeling, the features of transients and energy exchange in electric drive systems are considered. In conclusion, the advantages and disadvantages and technical and economic characteristics of an energy-saving electric drive system with supercapacitors compared to a system with active rectifier are discussed.

The article discusses the analysis of transients in the energy storage device as an element of a frequency-controlled electric drive. The energy storage device, based on supercapacitors, is connected to the DC link of a frequency converter through a bi-directional DC-DC converter and has a single-loop control system of external current. The aim of research is to identify the dynamics characteristics of the energy storage device with accounting the discrete properties of DC-DC converter. Simulation was carried out both with and without accounting the discreteness of the DC-DC converter. In the first case, the mathematical model of the DC-DC converter power part was built with using the SimPowerSystems library of Matlab application. In the second case, the averaged DC-DC converter model was used. In the article the influence of control system performance, the PWM frequency of the DC-DC converter and the capacitance of the DC link capacitor on the accuracy of inverter voltage stabilization is also considered. The article shows that the using of a double-integrating current control system with high performance and an increasing the PWM frequency of DCDC converter allows to obtain high accuracy of voltage stabilization in transition modes at the level of 5%.

A mathematical model of the frequency converter power part with a PWM inverter and energy storage device with a DC/DC converter is given. The models of PWM inverter and DC/DC converter are based on the continuous approximation principle of switching functions. Single-loop, double-loop and three-loop types of control systems for energy storage devices are considered. The structures and parameters of controllers were obtained by the synthesis method of subordinate control systems with a modular optimum tuning. The research aim is to identify the static and dynamic properties of control systems with an energy storage device as a part of an electric drive operating in the intermittent mode. The simulation results and comparative estimation of the control systems characteristics are given. The results can be useful in the development of control systems for energy storage devices.

In this paper a single-loop automatic control system for a DC-DC converter is considered. Bidirectional DC-DC converter is used to connect the block of supercapacitors to the DC link of the frequency converter in order to increase the energy efficiency of the electric drive. The paper formulates the requirements for the control system of DC-DC converter, describes the DC-DC converter as a control object, and considers the synthesis for non-linear current controllers. This paper compares a single-loop control system with three different types of current controllers. The paper presents the simulation results for all variants of DC-DC converter control systems, which show, that in a single-loop control system the using of a PI current controller leads to significant errors.

The article presents a selection procedure for the components selection of a bidirectional DC-DC. The converter is used to implement energy storage system as part of a photovoltaic power supply system. The storage system provides energy balance and smooth voltage oscillations in the power supply system's DC link via controlling energy flows. The considered approach can be used in photovoltaic and electric vehicles and electric drives applications. The paper includes a description of power components selection based on physical properties and power supply system requirements. Besides, an economic analysis of components as a part of power supply system is considered.

This paper deals with stator current control in scalar control system of frequency controlled induction motor drives and describes mathematical model of induction motor's stator current unit taking into account induction motor's electromagnetic transient responses. Several stator current controller's with signal adaptation structures have been tested, such as based on both constant and variable parameters PID-controller. Also an approach to controller's parameters synthesis is described. For the proposed control system's properties estimation the following time-domain criteria were selected: transient response time, overshoot, maximum reaching time. Reactions for both reference and disturbing influences have been tested. It is shown that application of PID-controller with variable parameters and signal adaptation provides high performance combined with robustness toward disturbances, as which internal electromotive force inducted in rotor circuit are taken into account. Rational field of use for proposed current controller with signal adaptation are scalar control system with enhanced electromagnetic torque forming ability.

A description of variable frequency electric drive with an energy storage device based on supercapacitor connected to the DC link of PWM inverter through a bidirectional DC/DC converter is given. The energy storage device has a single-loop control system of external current for a bidirectional DC/DC converter. The structure of the current controller and the function of the elements are illustrated. The simulation results, for various options for the initial charge of the DC link capacitor and a supercapacitor in energy storage device at various voltage levels, are given. The research aim is to identify the transient features in energy storage device and electric drive. The results can be useful in the control systems development for energy storage devices to improve the energy efficiency of variable frequency drives.