HEV 2017 Symposium Braunschweig hofer powertrain GmbH A company of the hofer AG 72622 Nürtingen Ohmstr. 15 email: info@hofer.de
Comparison of high power edrive solutions High Current edrives are mainly characterized by higher DC and AC currents Requirements for High Current solutions Mechanical power: 500 kw Electrical driving range: 500 km E-Motor technology: ASM (PSM) E-Motor speed: 22.000 rpm Maximum DC voltage: 450 V Maximum AC current: 1.500 A rms High Voltage edrives are mainly characterized by higher DC and AC voltages Requirements for High Voltage solutions Mechanical power: 500 kw Electrical driving range: 500 km E-Motor technology: PSM (ASM) E-Motor speed: 16.000 rpm Maximum DC voltage: 900 V Maximum AC current: 750 A rms The vehicles shown above are typical examples of high voltage and high current passenger cars.
Comparison of high power edrive solutions High Current solutions Advantages Norm compliant DC voltage (LV123 HV_2b) Clearly defined and small clearance and creepage distances Relatively small design Bigger power reserves for higher speeds Already existing base components Disadvantages Big cross sections due to very high AC currents Highest requirements for transition resistors for power distribution High DC charging currents and longer battery charging times due to thermal causes (I²R) Higher total weight in comparison High Voltage solutions Advantages Shorter battery charging times due to lower thermal stress (I²R) More degrees of freedom to increase torque at low speeds Defuse the target conflict between performance and terminal behavior Relatively low total weight Disadvantages Sometimes not norm compliant DC voltage ( LV123 HV_3) Less existing base components available compare to high current solution Increased isolation requirements more space requirements
Hofer focuses on high current power electronics Main reason Already existing base components: To speed up development time Lower risk within development processes LV parts can be reused Possible designs 1. Double inverter with 6-phase electric motor Limitation Bottleneck for the development is the inverter No power modules for automotive applications available with currents exceeding 600A (under real conditions) 2. Double inverter with two 3-phase electric motors Combine both solutions within one flexible hardware and further improve the solution
hofer double inverter eds lynx hledi1000 Specifications Voltage level: 450 V (nominal), 500 V (max) Peak Current: 1000 A rms (30 sec.) Cont. Current: 500 A rms (cont.) Volume: 10,3 l (300 x 265 x130 mm) Weight: 16 kg Efficiency: 98 % Features High flexibility (2x 3-phase or 6-phase EM) Optimized control for PSM and ASM Fast time to market (B sample maturity level, SOP in Q1/2018) Reliable safety concept (ASIL D) Variable switching frequency (from 5 khz to 12 khz) Customized interfaces (connectors and signals) Full protection concept (self protecting system) Automatic parameter adaptation High power density (up to 23 kw/kg) Integration of VCU and TCU possible
Further improvements eds lynx hledi1000 Sandwich-cooling concept Increased cooling capability Reduced installation space Interleave PWM strategy 6-phase EM - phase shift between 2 subsystems Reduced current ripple Smaller DC-link capacitor possible Limp home mode Only one working power module needed Half the power output remains superior to derating strategies Very high reliability (failure only possible after multiple errors) e.g. Improvements lead to compact design with low inductance
Thermal verification eds lynx hledi1000 Continuous power (30min) Boundary Conditions: Temp. Ambient: 105 C Temp. Cooling Inlet: 65 C Iph: 410Arms Vdc: 350V fp: 10kHz fel: 100Hz 1. 3. 2. 1. In continuous operation only the AC busbars heat up significantly. Estimated steady state temperature for 1h operation might reach 135 C new concept for next sample 2. Air temperature increases <10 from 85 C to 95 C 3. PCB temperature of drive Board reaches 112 C 13 C safety margin left
Thermal verification eds lynx hledi1000 High power (30sec) Boundary Conditions: Temp. Ambient: 105 C Temp. Cooling Inlet: 65 C Iph: 630Arms Vdc: 350V fp: 10kHz fel: 150Hz 1. 3. 4. 2. 1. The AC busbars rise only 5 C, even at 105 C ambient temperature 2. DC-link capacitor and inside air temperature staying constant 3. At high currents junction temperature is rising up to 115 C 4. PCB temperatures are not thermally influenced by 30 s high power operation
Thermal verification eds lynx hledi1000 Peak power (10sec) Boundary Conditions: Temp. Ambient: 80 C Temp. Cooling Inlet: 65 C Iph: 930Arms Vdc: 350V fp: 10kHz fel: 150Hz 1. 3. 2. 4. 1. The AC busbars rise only 3 C 2. DC-link capacitor and inside air temperature staying constant 3. At peak currents junction temperature is rising up to 145 C 4. PCB temperatures are not thermally influenced by 10 s peak operation
Examples of high current electric drives High performance electric axle P4 axle drive solution 6-phase EM (ASM) with double inverter 2 stage reduction gearbox Power output: 240 kw (peak) / 60 kw (cont.) EM torque: 420 Nm (peak) / 120 Nm (cont.) Max. EM speed: 15.000 rpm Gearbox ratio: 9,6 Total weight: <125 kg Full flexibility with installation angle no additional pump for cooling needed Installation on front and rear axle possible
Examples of high current electric drives High performance torque vectoring axle P4 axle drive solution Two 3-phase EM (ASM) with one double inverter Two separate and individual gearboxes build into one housing Power output: 360 kw (peak) EM torque: 560 Nm (Max.) Max. EM speed: 16.000 rpm Gearbox ratio: 9,95 Total weight: <180 kg Solution with torque vectoring Installation on front and rear axle possible
Highest efficiency for hofer electric drive system Maximum efficiencies Double inverter: 98,5 % 6 phase electric motor: 93,5 % Combined efficiency: 92 % Voltage reserve with 750 V IGBTs Very fast switching possible Combined efficiency map (PE & EM) Efficiency map for electric motor
Developments for 48V electric drive systems Why 48V systems? 48V systems strongly requested by customers Mostly hybrid applications small package Reduction of CO 2 emissions if needed add-on solutions Different car models and use cases (e.g. cold start, boost, reduce vibrations) flexible integration No high voltage system is needed improves cost and safety Requirements Power output from 20 to 30kW High currents (up to 600A) Very compact design with high level of integration Additional functional improvements (compared to common belt starter generator motors) 48V electric drive system face similar challenges like HV systems
48V concept study by hofer PEU Design DC-link capacitor Power modules Drive & control boards Directly mounted PEU (at EM B-side shield) Round design shape Max current: 500 A rms Dimensions of PEU: 200 x 86 mm PEU Weight: : <3 kg DC-link: power ring film capacitor for 86mm High ripple current capability, but custom development EM Interface Direct connection with busbars Hall-sensor directly on control board Magnet at the end of the EM shaft 200mm Potential to reduce EM length due to compact pos. sensing solution PEU = Power Electronics Unit
48V concept study by hofer EM Design P0/P1 solution 3-phase PSM Power output: 24 kw (peak) EM torque: 38 Nm (peak) Max. EM speed: 27.000 rpm EM Weight: <20 kg Dimensions of EM: 170 mm x 200 mm (l x d) Integration into gearbox possible
Future challenges and outlook Even higher power demands Combined solution for high current and high voltage Electric vehicles will need faster battery charging (with higher ranges available) Stronger power modules will be on the market in the next years boost high current solutions from today Increasing complexity of drivetrain topologies Flexible development with generic solutions More double inverters for different types of electric motors Highly integrated solutions cost and space advantages Future market trends Further increasing number of niche customers Plug & Play system solutions (not only components) Cherry picking will start with more competition and available components solutions have to be easily adaptable and apply to common standards
Thank you for your attention Thomas Langner Head of Software & Application hofer eds GmbH a company of the hofer AG Sedanstraße 21b D - 97082 Würzburg Tel.: +49 931 359335-401 Fax: +49 931 359335-129 Mobil: +49 170 7980635 thomas.langner@hofer.de