EPE Association: EPE 2015 - LS1b: Power Converters for Electric Vehicles

EPE 2015 - LS1b: Power Converters for Electric Vehicles
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2015 ECCE Europe - Conference > EPE 2015 - Topic 08: e-Mobility > EPE 2015 - LS1b: Power Converters for Electric Vehicles

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   Disc Inverter in Highly Integrated 9-phase Drivetrain for E-Mobility
By Philip BROCKERHOFF [View]
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Abstract: The paper describes the mechatronic integration of a nine phase electric motor and inverter for an electric car. Special focus is on the electronic development of a disc shaped 9-phase IGBT inverter integrated into the motor lid. The drive comprises automotive functional safe multicore ECU, rotational symmetric layout and sensor redundancy.

   Influence of Environmental Conditions on the Sensing Accuracy of Li-Ion Battery Management Systems with Passive Charge Balancing
By Thomas BLANK [View]
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Abstract: Due to their high storage capacity, low self-discharge rate and long lifetime Lithium-Ion batteries are key elements for the emerging electro-mobility and for stationary 'Battery Electrical Storage Systems' (BESS). However, Li-Ion batteries be handled very carefully to exploit their features optimally. Hence, 'Battery Management Systems' (BMS) have been developed to monitor precisely the voltage, temperature and current of the cells and the battery. These physical quantities are the basic variables to estimate the 'State of Charge' (SOC) of the battery. The exact knowledge of the SOC is essential to deploy a battery efficiently in an electric vehicle or a BESS. Thus, the effects of changing environmental conditions and their long-time impact on both, the Li-Ion cells and the measurement electronics have to be understood. This paper investigates the measurement electronics, so we designed a BMS in a master-slave configuration comprising a voltage monitor chip LTC6803 on a slave-board. The effect of changing climatic conditions on the BMS was evaluated by extensive stress tests. Thermal cycles spanning a range from -30 °C to +70 °C and hot humidity storage tests at 85 °C and 'Relative Humidity' (RH) levels of 20 \%RH and 85 \%RH were performed. Even after these accelerated tests the accuracy of the LTC slave board stayed within its specifications of 0.25\%. The accuracy of the U/I-slave board depends on static temperature dependent offsets of the hall sensor. Especially for low currents of 20 A the error exceeds 35\%, as the offset is based on the nominal current value of 200 A. However, by continuous temperature monitoring and calibration the precision target of 5\% can be reached, even for low currents. While the measurement precision is well suited to estimate the SOC of Li-Ion batteries containing 'Nickel-Manganese-Cobalt-Oxide' (NMC), it must be improved for LiFePO4-cells.

   Operation of Fault-Tolerant Non-Isolated Multiphase 3-Level DC-DC Converters for 48 V Automotive Power Systems
By Michael GLEISSNER [View]
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Abstract: The operation of a non-isolated, bidirectional DC--DC converter with several interleaving phases of 3-level flying capacitor modules for automotive power systems is analysed in theory and a 3-phase prototype implementation. Control techniques for equal phase current sharing and flying capacitor voltage balance are applied. The converter efficiency is compared to a status quo 2-level multiphase converter with protection switches. Moreover, the system behaviour in case of semiconductor switch failures is investigated. The 3-level modules are always superior to a 2-level structure and need only the relatively small flying capacitor as additional component.

   Optimization considerations for Interleaved DC-DC Converters for EV Battery charging applications, in terms of partial load efficiency and power density
By Marco JUNG [View]
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Abstract: This paper proposes a novel control strategy for multiphase interleaved dc-dc converters for EV batterycharging applications. The proposed control strategy allows to adapt the number of active phasesand the switching frequency according to the output power. This strategy results to an increased partialload efficiency and current handling capability of the semiconductors while the size of the semiconductor,the magnetic components and the cooling system size is reduced. An experimental validationof the proposed method is presented.

EPE 2015 - LS1b: Power Converters for Electric Vehicles
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2015 ECCE Europe - Conference > EPE 2015 - Topic 08: e-Mobility > EPE 2015 - LS1b: Power Converters for Electric Vehicles
	[return to parent folder]

	Disc Inverter in Highly Integrated 9-phase Drivetrain for E-Mobility By Philip BROCKERHOFF	[View] [Download]
Abstract: The paper describes the mechatronic integration of a nine phase electric motor and inverter for an electric car. Special focus is on the electronic development of a disc shaped 9-phase IGBT inverter integrated into the motor lid. The drive comprises automotive functional safe multicore ECU, rotational symmetric layout and sensor redundancy.

	Influence of Environmental Conditions on the Sensing Accuracy of Li-Ion Battery Management Systems with Passive Charge Balancing By Thomas BLANK	[View] [Download]
Abstract: Due to their high storage capacity, low self-discharge rate and long lifetime Lithium-Ion batteries are key elements for the emerging electro-mobility and for stationary 'Battery Electrical Storage Systems' (BESS). However, Li-Ion batteries be handled very carefully to exploit their features optimally. Hence, 'Battery Management Systems' (BMS) have been developed to monitor precisely the voltage, temperature and current of the cells and the battery. These physical quantities are the basic variables to estimate the 'State of Charge' (SOC) of the battery. The exact knowledge of the SOC is essential to deploy a battery efficiently in an electric vehicle or a BESS. Thus, the effects of changing environmental conditions and their long-time impact on both, the Li-Ion cells and the measurement electronics have to be understood. This paper investigates the measurement electronics, so we designed a BMS in a master-slave configuration comprising a voltage monitor chip LTC6803 on a slave-board. The effect of changing climatic conditions on the BMS was evaluated by extensive stress tests. Thermal cycles spanning a range from -30 °C to +70 °C and hot humidity storage tests at 85 °C and 'Relative Humidity' (RH) levels of 20 \%RH and 85 \%RH were performed. Even after these accelerated tests the accuracy of the LTC slave board stayed within its specifications of 0.25\%. The accuracy of the U/I-slave board depends on static temperature dependent offsets of the hall sensor. Especially for low currents of 20 A the error exceeds 35\%, as the offset is based on the nominal current value of 200 A. However, by continuous temperature monitoring and calibration the precision target of 5\% can be reached, even for low currents. While the measurement precision is well suited to estimate the SOC of Li-Ion batteries containing 'Nickel-Manganese-Cobalt-Oxide' (NMC), it must be improved for LiFePO4-cells.

	Operation of Fault-Tolerant Non-Isolated Multiphase 3-Level DC-DC Converters for 48 V Automotive Power Systems By Michael GLEISSNER	[View] [Download]
Abstract: The operation of a non-isolated, bidirectional DC--DC converter with several interleaving phases of 3-level flying capacitor modules for automotive power systems is analysed in theory and a 3-phase prototype implementation. Control techniques for equal phase current sharing and flying capacitor voltage balance are applied. The converter efficiency is compared to a status quo 2-level multiphase converter with protection switches. Moreover, the system behaviour in case of semiconductor switch failures is investigated. The 3-level modules are always superior to a 2-level structure and need only the relatively small flying capacitor as additional component.

	Optimization considerations for Interleaved DC-DC Converters for EV Battery charging applications, in terms of partial load efficiency and power density By Marco JUNG	[View] [Download]
Abstract: This paper proposes a novel control strategy for multiphase interleaved dc-dc converters for EV batterycharging applications. The proposed control strategy allows to adapt the number of active phasesand the switching frequency according to the output power. This strategy results to an increased partialload efficiency and current handling capability of the semiconductors while the size of the semiconductor,the magnetic components and the cooling system size is reduced. An experimental validationof the proposed method is presented.