In a 48V system the bidirectional DC/DC converter transfers energy between the 12V and the 48V domain:
- Typically the DC/DC supplies the components in the 12V network with power.
- It also works in the opposite direction and can supply the 48V components out of the 12V subnet.
The following diagram outlines a possible centralized architecture:
Some vehicle manufacturers migrate to a 48V decentralized power delivery architecture with individual smaller 1kW DC/DC converters in different domains. The advantages of this architecture can be.
- Flexibility on packaging
- The power conversion is closer to the load
- Optimization possible on cost with cooling methods due to lower temperature rise
- Redundancy in power supply in case of functional safety needs
- Save cost and weight on wiring harness
A further step in integration would be to place the DC/DC converter directly into the load, in example into a pump can reduce overall system costs. Please contact us to evaluate possible options for your system.
The block diagram below outlines a 3kW DC/DC centralized architecture that allows to
- Reduce the number of phases from 4/6 down to 3/4
- Reduce the system size due to higher switching frequencies
Complete 48V portfolio
Infineon offers a complete and broad system of chipset solutions – from microcontrollers, voltage regulators, transceivers to smart power drivers and very low-resistance MOSFETs – for 48V DC/DC applications.
Selected product highlights:
OPTIREG – voltage regulators:OPTIREG™ Switcher and PMIC are the ideal solution. The Pre-Regulator TLE6389-3G plus the Safety Supply PMIC TLF35584 offer stable supply to the AURIX™. The external safety device not only provides the power supply, but also monitors it and the functional status (e.g. watchdog) of the microcontroller and can be used for switching the system to a safe state (fail safe) in the event of a safety-relevant fault. This increases the availability of the system while allowing the microcontroller's error response to be individually configured.
CAN transceivers and bridge driver ICs:Other important communication and power components for 48V systems are CAN transceivers (e.g. TLE9250VSJ) and bridge driver ICs (e.g. TLE9180):
- TLE9180D-21QK and TLE9180D-31QK: advanced gate driver ICs dedicated to control six external N-channel MOSFETs forming an inverter for high current three phase motor drives application in the automotive sector. A sophisticated high voltage technology allows ICs to support applications for single and mixed battery systems with battery voltages of 12 V, 24 V and 48 V. Bridge, motor and supply related pins can withstand voltages of up to 90 V. Motor related pins can even withstand negative voltage transients down to - 15 V without damage. The TLE9180D-21QK has two integrated current sense amplifier (CSA) for shunt signal conditioning, whereas the TLE9180D-31QK has three CSA. Gain and zero current voltage offset can be adjusted by SPI. The offset can be calibrated. If isolation is required, a discrete component has to be added.
MOSFETs:48V applications are driving a high demand for 80V and 100V MOSFETs for applications such as starter-generators (belt-driven or integrated), DC/DC converters, battery main switches as well as 48V auxiliaries. Infineon's OptiMOS™-5 technology offers a broad portfolio of low RDS(on), scalable MOSFETs in various packages.
For high power requirements the MOSFETs in leadless TOLL package are offered for standard Cu substrates, while as alternative the TOLG package is targeting Al core IM substrates and Cu based substrates in conjunction with very high thermal cycle requirements. Both packages are footprint compatible and provide the highest current capability on a 10x11 mm2 footprint.
Next to these two package options, the TOLT package is supporting top side cooling on ECU level.
For medium and low power requirements like in DC/DC converters or at the 48V auxiliaries, the MOSFETs in 5x6 SSO8 package or in the 3x3 S3O8 package do complement Infineon’s MOSFET portfolio.
AURIX™ microcontroller:The AURIX™ TC2xx microcontroller family was first introduced into powertrain applications, but with up to 3 TriCore™ processor cores and up to 8MB flash, it has since become highly successful across many automotive applications such as safety, chassis and driver assistance systems. The AURIX™ TC2xx is highly scalable and suitable for a number of 48V applications, it offers ISO 26262 compliance so that it can be used in ASIL-D systems, plus the fact that it’s also used in high voltage applications means that customers can utilise a platform approach. Furthermore, HOT package options are offered, which can be a requirement in some 48V applications in harsh environments.
The successor to the TC2xx, the 40nm AURIX™ TC3xx family, offers a highly compatible future roadmap. It includes up to six independently operating 32-bit TriCore™ processor cores and up to 16MB flash, thus significantly boosting computing performance compared to the AURIX™ TC2xx. The feature rich TC3xx allows designers to upgrade their systems if required and choose from a broad portfolio of scalable memory sizes, peripheral functions, frequencies, temperatures and package options. The first TC3xx devices to be launched; the high end TC38x and the TC39x are already available. A superset approach has been utilized so they are compatible with lower end family members, more of which will be launched throughout 2020, many of which will be suitable for 48V applications.
The TC3xx family, like the TC2xx, offers the ideal combination of real-time capability, and functional safety for ISO 26262 systems up to ASIL-D, with the HOT package being offered throughout. An important enhancement is the inclusion of the Hardware Security Module (HSM) as standard. Security is not just a concern for systems communicating with the outside world, it is now a requirement for some customers, who specify that any microcontroller that communicates via the CAN network requires security. The TC3xx offers the HSM throughout the family, whereas previously it was available only on selected devices on the TC2xx. This offers customers who need security an upgrade path, with the HSM now offering EVITA Full capability, compared to EVITA medium on the TC2xx.
Dual Inverter drive for light electric vehicles
An efficient and low-cost way to implement electric drive in a light vehicle is to use two in-wheel motors and two inverter drives. This study outlines a proposed architecture and the safety standards that the system must meet.