Direct usage of photovoltaic solar panels to supply a freezer motor with variable DC input voltage

In this paper, a single-phase photovoltaic (PV) inverter fed by a boost converter to supply a freezer motor with variable DC input is investigated. The proposed circuit has two stages. Firstly, the DC output of the PV panel that varies between 150 and 300 V will be applied to the boost converter. The boost converter will boost the input voltage to a fixed 300 V DC. Next, this voltage is supplied to the single-phase full-bridge inverter to obtain 230 V AC. In the end, The output of the inverter will feed a freezer motor. The PV panels can be stand-alone or grid-connected. The grid-connected PV is divided into two categories, such as with a transformer and without a transformer, a transformer type has galvanic isolation resulting in increasing the security and also provides no further DC current toward the grid, but it is expensive, heavy and bulky. The transformerless type holds high efficiency and it is cheaper, but it suffers from leakage current between PV and the grid. This paper proposes a stand-alone direct use of PV to supply a freezer; therefore, no grid connection will result in no leakage current between the PV and Grid. The proposed circuit has some features such as no filtering circuit at the output of the inverter, no battery in the system, DC-link instead of AC link that reduces no-loads, having a higher efficiency, and holding enough energy in the DC-link capacitor to get the motor started. The circuit uses no transformers, thus, it is cheaper and has a smaller size. In addition, the system does not require a complex pulse width modulation (PWM) technique, because the motor can operate with a pulsed waveform. The control strategy uses the PWM signal with the desired timing. With this type of square wave, the harmonics (5th and 7th) of the voltage are reduced. The experimental and simulation results are presented to verify the feasibility of the proposed strategy

A single transformer for active cell equalization method of lithium-ion batteries with two times fewer secondaries than cells

In this paper, the concept of active cell-balancing technique, by using a multiple-outputs double-forward converter for lithium-ion (Li-ion) batteries, is investigated. It controls two times more cells than secondaries, and it equalizes eight cells in a series. In this method, four secondaries can reasonably be wound with the same back electromotive force (EMF). This means a low pin count on the transformer and a low bill of materials (BOM). The bridge uses four N-channel MOSFETs as switches, which means two times fewer transistors than cells, resulting in fewer switching losses. This scheme is applied for controlling the minimum voltage among the cells of the lithium-ion battery. It uses a multi-winding transformer based on a forward double converter structure. Conventional schemes using a multi-winding transformer for electric vehicles (EVs) require an equal number of secondaries per cell. This scheme requires one secondary for two adjacent cells, thus the number of secondaries is reduced by a factor of two. Also, the redistribution of charge from a high cell to a low cell does not require many switching components and little intelligence to determine low cell voltage detection. The basic principle of this method is to use the overall battery pack voltage as a reference to supply individual cells, using a forward converter containing a transformer with a well-chosen winding ratio. The experimental and simulation results are performed to verify the feasibility of the proposed system

Forward converter current fed equalizer for lithium based batteries in ultralight electrical vehicles

In this paper, the concept of a forward balancing technique fed by a buck converter for lithium-based batteries in Electrical Vehicle (EV) applications is investigated. The proposed active topology equalizes eight cells in a series in a battery pack, by using a forward converter for each battery pack and the whole battery packs, using a buck converter. The battery bank consists of four battery packs, which are in series. Therefore, the proposed system will equalize 32 cells in series. In this paper, the proposed circuit employs a single transistor used in a Zero Voltage Switch (ZVS) for the forward converter. In practice, this means a capacitor in parallel with the switch at the same time a demagnetizing of the transformer is obtained. The circuit realizes a low Electromagnetic Interference (EMI) and reduces ringing. To overcome the problem of many pins on a coil former, the transformer secondary windings are made by using hairpin winding, on a ring core. It permits, e.g., having eight secondaries and uniform output voltages. Each secondary winding is made by two hairpin turns using two zero-Ohm resistors in series. The proposed topology has less components and circuitry, and it can equalize multiple battery packs by using a single buck converter and several forward converters for each battery pack. Experimental and simulation results are performed to verify the viability of the proposed topology

A smart high-voltage cell detecting and equalizing circuit for LiFePO4 batteries in electric vehicles

A battery management system (BMS) plays an important role in electric vehicles (EVs) in order to achieve a reasonable-lasting lifetime. An equalizing method is essential in order to obtain the best performance. A monitoring system is required to check if any cell voltage is high or low. In this paper, an equalizing and monitoring system for an ultra-light electric vehicle is proposed. The monitoring system detects if one cell is fully charged or all cells are fully charged and the equalizing system tops each cell at the desired voltage. To solve this issue, a light-emitting diode (LED) band gap is used as a voltage reference to inform the user if any cell is at its high voltage. A smart monitoring displays on the liquid crystal display (LCD), if one cell is high or all cells are high. This detection also provides a signal to the microcontroller to turn on/off the charger if all cells are high. Also, a Bluetooth module was designed to command the microcontroller the charger to turn on/off via voice/text message by using a smartphone. Additionally, a new smart monitoring system based on the Bluetooth model (HC05) and mobile app has been made in order to monitor individual cell voltage. A major feature of the system is to draw a very-low current, so that the system does not contribute significantly to the self-discharge of the battery and the circuit does not need sophisticated control. Manufacturers of large electric vehicles may have more intelligent systems that may require a permanent connection to the grid and allow high standby losses, where more state of charge (SOC) may be lost per day. The paper is rather focused on reducing the standby losses, and to activate the equalizer only when charging and/or driving. The experimental results are performed in order to verify the feasibility of the proposed circuit

An efficient equalizing method for lithium-ion batteries based on coupled inductor balancing

This article developed a coupled inductor balancing method to overcome cell voltage variation among cells in series, for Lithium Ion (Li-ion) batteries in Electrical Vehicles (EV). For an "eight cells in series" example, the developed balance circuit has four inductors, one magnetic circuit with one winding per two cells, and one control switch per cell, as compared to the traditional inductor-based equalizer that needs N-1 inductors and magnetic circuits for N number of cells and more switches. Therefore, ultimately, a more efficient, cost-effective circuit and low bill of materials (BOM) will be built up. All switches are logic-level N-Channel metal-oxide-semiconductor field-effect transistors (MOSFETs) and they are controlled by a pair of complementary signals in a synchronous trigger pattern. In the proposed topology, less components and fast equalization are achieved compared to the conventional battery management system (BMS) technique for electrical vehicles based on the inductor balancing method. This scheme is suitable for fast equalization due to the inductor-based balancing method. The inductors are made with a well-chosen winding ratio and all are coupled with one magnetic core with an air gap. Theoretical derivation of the proposed circuit was well-presented, and numerical simulation relevant to the electrochemical storage devices was conducted to show the validity of the proposed balance circuit. A complete balance circuit was built to verify that the proposed circuit could resolve imbalance problems which existed inside battery module

A Ćuk converter cell balancing technique by using coupled inductors for lithium-based batteries

In this paper, a ćuk converter balancing method by using a coupled inductor for lithium based batteries is investigated. The proposed circuit is an active balancing circuit that will equalize eight battery cells in a series. In electrical vehicles (EV), a battery management system (BMS) is a vital task to achieve the best performance of the batteries and longer lifetime. The problem of voltage difference in a battery pack is an important issue to be improved. To overcome the voltage differences in battery string, an equalizing method is mandatory. The conventional ćuk converter requires 2(n-1) switches to balance n cells, while the proposed circuit requires only n switches for n cells in series. In addition, the proposed developed topology uses coupled inductors instead of un-coupled inductors, unlike the traditional ćuk converter balancing method. Since the ćuk balancing transfers the energy among two adjacent cells, it requires a proportionately long equalization time particularly for long string battery packs, but the coupled inductor ćuk converter type overcomes this problem. The switches are N-channel metal-oxide field-effect transistor (MOSFET) to achieve lower drain-source on-resistance, RDS(on), and less voltage drop as compared to the P-channels. The switches are triggered by complementary signals. The coupled inductor is made in such a way to hold the same magnetizing inductance. It can be done by using five wires in one hand. The circuit contains five inductors, one magnetic core, with five winding for eight cells, and one capacitor for two cells. Therefore, the overall circuitry and complexity of the circuit are reduced, resulting in a more cost-effective and easy to implement circuit. The system also does not demand complicated control for battery equalizing. The experimental circuit was implemented and simulation results were obtained to confirm the validity of the proposed system

A novel driving method for switched reluctance motor with standard full bridge inverter

This paper proposes a new driving method for a switched reluctance motor (SRM) by using a standard full bridge. The windings in the SRM are connected in series to build a ring structure, where a controllable DC source is inserted. Based on the new structure, the theoretical analysis and calculation are made to determine the control parameters. Besides three-phase SRM, the new idea can also be applied to the SRMs with four and five phases. The new driving method is compared with the conventional method by simulation. The results show that with the new method, the ripple of torque and speed in the SRM reduces. The influence of the proposed method on the power rating and losses is then analyzed. The validation is also made to verify the application of the new method and the difference between the conventional driving method and the proposed method. The measured results match the simulated results well

Controlling a switched reluctance motor with a conventional three phase bridge instead of asymmetric H-bridges

This paper proposes a new driving method for switched reluctance motor (SRM), by using the standard full-bridge inverter. In spite of changing the internal structure of an SRM, the proposed method uses an extra ring structure circuit to make it possible for the inverter to drive the SRM. Next to the standard converter, a controllable DC source is needed. With the theoretical analysis and calculation, the reference value of the circulating current in the ring structure is determined and the new method is proven via simulation. A comparison is made with the conventional method for driving an SRM: the asymmetric H-bridges. Also the current studies are then made to confirm that the SRM can be controlled without lowering the performance of the machine. The experimental verification is also made under different conditions, as well as the comparison with the simulation results

Global, regional, and national burden of colorectal cancer and its risk factors, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Funding: F Carvalho and E Fernandes acknowledge support from Fundação para a Ciência e a Tecnologia, I.P. (FCT), in the scope of the project UIDP/04378/2020 and UIDB/04378/2020 of the Research Unit on Applied Molecular Biosciences UCIBIO and the project LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy i4HB; FCT/MCTES through the project UIDB/50006/2020. J Conde acknowledges the European Research Council Starting Grant (ERC-StG-2019-848325). V M Costa acknowledges the grant SFRH/BHD/110001/2015, received by Portuguese national funds through Fundação para a Ciência e Tecnologia (FCT), IP, under the Norma Transitória DL57/2016/CP1334/CT0006.proofepub_ahead_of_prin

The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019

Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe