EPE Association: EPE 2019 - DS3k: Electric Vehicle Propulsion Systems and their Energy Storage

EPE 2019 - DS3k: Electric Vehicle Propulsion Systems and their Energy Storage
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2019 ECCE Europe - Conference > EPE 2019 - Topic 08: Electric Vehicle Propulsion Systems and their Energy Storage > EPE 2019 - DS3k: Electric Vehicle Propulsion Systems and their Energy Storage

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   A low-cost, high-power-density DC-DC converter for hybrid and electric vehicle applications
By Md Rishad AHMED [View]
[Download]

Abstract: A 400 V to 12 V soft-switching DC-DC converter is designed to supply power to the low-voltage system of the hybrid and electric vehicle from the high-voltage battery. The use of soft-switching topology, SiC MOSFET and an optimised design of the transformer and filter inductors enables a low profile layout for the converter. Optimised layouts of the components increased its volumetric and specific power density over the commercial state-of-the-arts and ensured a simple construction process. The 3.5 kW converter achieved a volumetric power density of 2 kW / litre and a specific power density of 1.2 kW / kg. The prototype converter operated at 3.6 kW, 150 kHz, 425 - 13 V and achieved 87\% efficiency. Experimental results from 100 W to 3.6 kW operations verified the superiority of the soft-switching topology over hard-switching operations.

   A Novel Current Ripple Cancellation PWM for Isolated Three-phase Matrix DAB AC-DC Matrix Converter
By Shunsuke TAKUMA [View]
[Download]

Abstract: The control method for an isolated three-phase matrix dual active bridge (DAB) AC to DC converter is proposed to control sinusoidal grid current waveforms with a minimum reactive current. The conventional SVM based on a constant current is not applied to the isolated three-phase matrix DAB AC to DC converter due to a high di/dt by employing a leakage inductance. Therefore, the duty calculation for the matrix converter is required to approximate the waveforms at a high-frequency transformer or implement a numerical calculation. However, the gird currents are distorted due to the error by such approximation. In addition, the numerical calculation is used as a complex implementation and requires a long calculation time. In this paper, the novel modulation method based on the current ripple cancelation is proposed for the isolated three-phase matrix DAB AC to DC converter. The high di/dt ripple current against current reference is canceled by the sum of the currents during the positive and negative half switching cycle without the leakage inductance value. The input and output dc current controls are achieved considering the effects of the leakage inductance. A continuous current mode (CCM) and discontinuous current mode (DCM) on buck and boost modes are clarified and confirmed by simulation. As the simulation results, the input current THD is reduced by 88.2\% compared with the conventional method. As experimental results, the input current THD of 3.8\% is achieved at rated power with CCM and DCM operation.

   Comparison of methods for compensation capacitor calculation in a three-phase wireless power transfer system
By Shuang NIE [View]
[Download]

Abstract: This paper proposes a new approach to calculate the compensation capacitors values for high power three-phase wireless power transfer systems, suitable for deployment in wireless EV chargers. The proposed approach increases the power factor of transmitter phases, and thus reduces the dc bus voltage requirement significantly for systems with non-decoupled transmitter coils. The proposed approach derives the compensation capacitor values as a function of rated transmitter currents. The paper applies the transmitter currents from perfect alignment and extreme misalignment into the proposed approach to derive two sets of compensation capacitors. One set of capacitors provides unity power factors for each phase at perfect alignment while the other set of capacitors provides unity power factor for the phase delivering highest power for all misalignments. Simulation verification is performed at 3.3 kW output power and 300 V battery voltage showing that the proposed method can reduce the dc bus voltage requirement to below 800 V for all misalignments. Experimental results are obtained at 1000 W output power and 150 V battery voltage verifying the proposed approach.

   Extending the cruising distance of fuel cell electric vehicles by active motor-generator loss control
By Shuhei KATO [View]
[Download]

Abstract: Small capacity battery of fuel cell electric vehicles (FCEVs) may cause regenerative braking to become disabled halfway through long downhill. To prevent brake lost accident, FCEVs mount a huge discharge resistor which restricts hydrogen space. Then this paper proposes motor-generator loss increase control as a substitute for the resistor. The proposed method realizes sufficient braking force without charging the FCEV battery by converting the braking energy into the motor-generator and its inverter losses. The algebraic analysis of the current vector set-point of the proposed method using motor-generator parameters is clarified. Moreover the principle of the proposed method was verified by small scale experiments using 2-kW machine. By using the proposed method, it is possible to mount additional hydrogen tank instead of the resistor and extend the cruising distance.

   Loss and Thermal Analysis of a 100 kW Converter Module Mounted on a Cold-Plate for Fast Charging Applications
By Amir Sajjad BAHMAN [View]
[Download]

Abstract: For a 100 kW power converter module for fast charging application, the loss and thermal analysis are performed where the results are presented in this paper. The two-stage power conversion of the converter has an efficiency value of 95\%. A liquid cooling system is designed, and thermal performance analysis is performed. The results show that the junction temperature is maintained below 110_ for 8 liters per minute of liquid flow rate by the cooling system.

   Measuring and Characterization of a Pedal Electric Cycle (Pedelec) on a Full System Test-Bench with Full Range Emulation of a Cyclist
By Michael SCHMITT [View]
[Download]

Abstract: This paper describes the development of a pedelec test-bench and the measurement of a pedelec tocharacterize the propulsion system. The main idea of the test-bench is to emulate a real driver moreprecisely then other state of the art test-benches. This means precise, bilateral pedal torque inducementand direct emulation of the road by a roller. Precise measurement equipment and dynamic controlenables versatile measurements with the proposed test-bench. Different measurements are introducedamongst others: assistance level, dynamic control behavior, distance and efficiency with full rangeemulation of a cyclist.

   Optimization of the discharge cut-off voltage in LiFePO4 battery packs
By Xin SUI [View]
[Download]

Abstract: Considering that the voltage and capacity/energy level of a single battery cell cannot meet therequirements of electric vehicles, hundreds of battery cells are usually connected in series/parallel. Thedischarge cut-off voltage of the battery cells is an important factor affecting the consistency of theterminal voltage and the capacity usage efficiency (i.e., the ratio of the discharged capacity to the nominalcapacity) for a battery pack. This paper presents an optimization method for determining the LiFePO4battery cell discharge cut-off voltage considering three factors: capacity usage efficiency, terminal voltagedispersion, and minimum terminal voltage. By applying this optimization method to different number ofseries-connected battery cells, the relationship between the optimized discharge cut-off voltage and thenumber of battery cells is deduced, and this relationship is instructive for the operation of the battery pack.Compared with the conventional method where the discharge cut-off voltage is 2 V, the terminal voltagedispersion is greatly reduced and the maximum rate of variation is 10.7\%. At the same time, the minimumterminal voltage increases by about 1.5\% and the capacity usage efficiency only declines by about 0.5\%.Consequently, the battery cells will not be over-discharged because the minimum terminal voltage islarger than 2 V. The rate of decline of the capacity usage efficiency is small and it can be ignored.Moreover, the level of consistency among the terminal voltage of the battery cells is improved andlifetime of the battery pack will be extended.

   Reconfiguration of fault-tolerant inverters with reduced maximum output voltage or current in combination with permanent magnet synchronous machines
By Michael GLEISSNER [View]
[Download]

Abstract: Most fault-tolerant inverters have either a reduced maximum output voltage or current in degraded mode after a failure. With a reduced maximum output voltage, the field-weakening range in the speed-torque range of an electric machine is shifted to lower speeds and the maximum achievable torque at higher speeds is reduced. A current reduction is directly linked with a reduction of the maximum torque. Depending on the speed-torque operation point of the electric machine, several control aspects of the machine have to be regarded for a successful reconfiguration. All relevant scenarios are analysed by simulations for a permanent magnet synchronous machine.

   Series Resonant Converter for DC fast-charging electric vehicles with wide output voltage range
By Assil BOUACH [View]
[Download]

Abstract: The paper presents an investigation of the operating range achievable with a series resonant converter. In its fully resonant mode, the series resonant converter is an attractive topology due to the switching at zero current, which results in high efficiency. The question that is addressed by this paper is if the topology is applicable for fast dc charging of electric vehicles, that is if it can cover the required operating range and what effective efficiency is achieved over this operating range.

   Wireless Battery Charger based on Sensorless Control for E-bike Station
By Pasquale FRANZESE [View]
[Download]

Abstract: The paper suggests a battery wireless charging control for e-bike sharing service implemented atUniversity `Federico II' of Naples. The wireless battery charging system is based on Series-SeriesResonant Converter (SS-RIPT) tracking of battery Constant Voltage (CV)/Constant Current (CC) mode.State of charge identification has been implemented using primary transformer current measurement. A Fourier frequency domain methodology has been implemented in order to identify the secondary coil current of resonant transformer and the battery voltage. Numerical results have been carried out in order to validate the identification procedure.

EPE 2019 - DS3k: Electric Vehicle Propulsion Systems and their Energy Storage
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2019 ECCE Europe - Conference > EPE 2019 - Topic 08: Electric Vehicle Propulsion Systems and their Energy Storage > EPE 2019 - DS3k: Electric Vehicle Propulsion Systems and their Energy Storage
	[return to parent folder]

	A low-cost, high-power-density DC-DC converter for hybrid and electric vehicle applications By Md Rishad AHMED	[View] [Download]
Abstract: A 400 V to 12 V soft-switching DC-DC converter is designed to supply power to the low-voltage system of the hybrid and electric vehicle from the high-voltage battery. The use of soft-switching topology, SiC MOSFET and an optimised design of the transformer and filter inductors enables a low profile layout for the converter. Optimised layouts of the components increased its volumetric and specific power density over the commercial state-of-the-arts and ensured a simple construction process. The 3.5 kW converter achieved a volumetric power density of 2 kW / litre and a specific power density of 1.2 kW / kg. The prototype converter operated at 3.6 kW, 150 kHz, 425 - 13 V and achieved 87\% efficiency. Experimental results from 100 W to 3.6 kW operations verified the superiority of the soft-switching topology over hard-switching operations.

	A Novel Current Ripple Cancellation PWM for Isolated Three-phase Matrix DAB AC-DC Matrix Converter By Shunsuke TAKUMA	[View] [Download]
Abstract: The control method for an isolated three-phase matrix dual active bridge (DAB) AC to DC converter is proposed to control sinusoidal grid current waveforms with a minimum reactive current. The conventional SVM based on a constant current is not applied to the isolated three-phase matrix DAB AC to DC converter due to a high di/dt by employing a leakage inductance. Therefore, the duty calculation for the matrix converter is required to approximate the waveforms at a high-frequency transformer or implement a numerical calculation. However, the gird currents are distorted due to the error by such approximation. In addition, the numerical calculation is used as a complex implementation and requires a long calculation time. In this paper, the novel modulation method based on the current ripple cancelation is proposed for the isolated three-phase matrix DAB AC to DC converter. The high di/dt ripple current against current reference is canceled by the sum of the currents during the positive and negative half switching cycle without the leakage inductance value. The input and output dc current controls are achieved considering the effects of the leakage inductance. A continuous current mode (CCM) and discontinuous current mode (DCM) on buck and boost modes are clarified and confirmed by simulation. As the simulation results, the input current THD is reduced by 88.2\% compared with the conventional method. As experimental results, the input current THD of 3.8\% is achieved at rated power with CCM and DCM operation.

	Comparison of methods for compensation capacitor calculation in a three-phase wireless power transfer system By Shuang NIE	[View] [Download]
Abstract: This paper proposes a new approach to calculate the compensation capacitors values for high power three-phase wireless power transfer systems, suitable for deployment in wireless EV chargers. The proposed approach increases the power factor of transmitter phases, and thus reduces the dc bus voltage requirement significantly for systems with non-decoupled transmitter coils. The proposed approach derives the compensation capacitor values as a function of rated transmitter currents. The paper applies the transmitter currents from perfect alignment and extreme misalignment into the proposed approach to derive two sets of compensation capacitors. One set of capacitors provides unity power factors for each phase at perfect alignment while the other set of capacitors provides unity power factor for the phase delivering highest power for all misalignments. Simulation verification is performed at 3.3 kW output power and 300 V battery voltage showing that the proposed method can reduce the dc bus voltage requirement to below 800 V for all misalignments. Experimental results are obtained at 1000 W output power and 150 V battery voltage verifying the proposed approach.

	Extending the cruising distance of fuel cell electric vehicles by active motor-generator loss control By Shuhei KATO	[View] [Download]
Abstract: Small capacity battery of fuel cell electric vehicles (FCEVs) may cause regenerative braking to become disabled halfway through long downhill. To prevent brake lost accident, FCEVs mount a huge discharge resistor which restricts hydrogen space. Then this paper proposes motor-generator loss increase control as a substitute for the resistor. The proposed method realizes sufficient braking force without charging the FCEV battery by converting the braking energy into the motor-generator and its inverter losses. The algebraic analysis of the current vector set-point of the proposed method using motor-generator parameters is clarified. Moreover the principle of the proposed method was verified by small scale experiments using 2-kW machine. By using the proposed method, it is possible to mount additional hydrogen tank instead of the resistor and extend the cruising distance.

	Loss and Thermal Analysis of a 100 kW Converter Module Mounted on a Cold-Plate for Fast Charging Applications By Amir Sajjad BAHMAN	[View] [Download]
Abstract: For a 100 kW power converter module for fast charging application, the loss and thermal analysis are performed where the results are presented in this paper. The two-stage power conversion of the converter has an efficiency value of 95\%. A liquid cooling system is designed, and thermal performance analysis is performed. The results show that the junction temperature is maintained below 110_ for 8 liters per minute of liquid flow rate by the cooling system.

	Measuring and Characterization of a Pedal Electric Cycle (Pedelec) on a Full System Test-Bench with Full Range Emulation of a Cyclist By Michael SCHMITT	[View] [Download]
Abstract: This paper describes the development of a pedelec test-bench and the measurement of a pedelec tocharacterize the propulsion system. The main idea of the test-bench is to emulate a real driver moreprecisely then other state of the art test-benches. This means precise, bilateral pedal torque inducementand direct emulation of the road by a roller. Precise measurement equipment and dynamic controlenables versatile measurements with the proposed test-bench. Different measurements are introducedamongst others: assistance level, dynamic control behavior, distance and efficiency with full rangeemulation of a cyclist.

	Optimization of the discharge cut-off voltage in LiFePO4 battery packs By Xin SUI	[View] [Download]
Abstract: Considering that the voltage and capacity/energy level of a single battery cell cannot meet therequirements of electric vehicles, hundreds of battery cells are usually connected in series/parallel. Thedischarge cut-off voltage of the battery cells is an important factor affecting the consistency of theterminal voltage and the capacity usage efficiency (i.e., the ratio of the discharged capacity to the nominalcapacity) for a battery pack. This paper presents an optimization method for determining the LiFePO4battery cell discharge cut-off voltage considering three factors: capacity usage efficiency, terminal voltagedispersion, and minimum terminal voltage. By applying this optimization method to different number ofseries-connected battery cells, the relationship between the optimized discharge cut-off voltage and thenumber of battery cells is deduced, and this relationship is instructive for the operation of the battery pack.Compared with the conventional method where the discharge cut-off voltage is 2 V, the terminal voltagedispersion is greatly reduced and the maximum rate of variation is 10.7\%. At the same time, the minimumterminal voltage increases by about 1.5\% and the capacity usage efficiency only declines by about 0.5\%.Consequently, the battery cells will not be over-discharged because the minimum terminal voltage islarger than 2 V. The rate of decline of the capacity usage efficiency is small and it can be ignored.Moreover, the level of consistency among the terminal voltage of the battery cells is improved andlifetime of the battery pack will be extended.

	Reconfiguration of fault-tolerant inverters with reduced maximum output voltage or current in combination with permanent magnet synchronous machines By Michael GLEISSNER	[View] [Download]
Abstract: Most fault-tolerant inverters have either a reduced maximum output voltage or current in degraded mode after a failure. With a reduced maximum output voltage, the field-weakening range in the speed-torque range of an electric machine is shifted to lower speeds and the maximum achievable torque at higher speeds is reduced. A current reduction is directly linked with a reduction of the maximum torque. Depending on the speed-torque operation point of the electric machine, several control aspects of the machine have to be regarded for a successful reconfiguration. All relevant scenarios are analysed by simulations for a permanent magnet synchronous machine.

	Series Resonant Converter for DC fast-charging electric vehicles with wide output voltage range By Assil BOUACH	[View] [Download]
Abstract: The paper presents an investigation of the operating range achievable with a series resonant converter. In its fully resonant mode, the series resonant converter is an attractive topology due to the switching at zero current, which results in high efficiency. The question that is addressed by this paper is if the topology is applicable for fast dc charging of electric vehicles, that is if it can cover the required operating range and what effective efficiency is achieved over this operating range.

	Wireless Battery Charger based on Sensorless Control for E-bike Station By Pasquale FRANZESE	[View] [Download]
Abstract: The paper suggests a battery wireless charging control for e-bike sharing service implemented atUniversity `Federico II' of Naples. The wireless battery charging system is based on Series-SeriesResonant Converter (SS-RIPT) tracking of battery Constant Voltage (CV)/Constant Current (CC) mode.State of charge identification has been implemented using primary transformer current measurement. A Fourier frequency domain methodology has been implemented in order to identify the secondary coil current of resonant transformer and the battery voltage. Numerical results have been carried out in order to validate the identification procedure.