E-Mobility Engineering 019 | In conversation: Stephen Lambert l WAE EVR l Battery case materials focus l Quality control insight l Clipper Automotive Clipper Cab digest l Optimising battery chemistries insight l Powertrain testing focus

8 May/June 2023 | E-Mobility Engineering TheGrid Cell simulator for latestmonitors GaN-based800V inverter design M icroNova has enhanced its Cell Module Controller (CMC) simulator to support the latest high- accuracy battery cell monitors and balancers from Texas Instruments, or TI (writes Nick Flaherty). The NovaCarts CMC simulator has a daisy-chain comms interface to the bridge device on the master board of the BMS or the master control unit to provide precise timing as well as accurate simulation. The simulator can handle up to 35 BQ79718-Q1 devices from TI. These are used as a monitoring, balancing and protection unit for battery modules in high-voltage BMSs, and engineers involved in developing and testing BMSs can also combine several of the simulators to simulate batteries with a large number of cells. “The BQ79718-Q1 allows automakers to maximise the true range of their EVs with high-precision battery cell voltage G aN Systems has developed an 11 kW, 800 V OBC inverter reference design using gallium nitride transistors (writes Nick Flaherty). The company says the design provides 36% higher power density and up to 15% lower bill of materials cost than using SiC transistors. The OBC combines a three-level flying capacitor topology in a bridgeless totem-pole power factor correction architecture for the AC-DC conversion, and a dual active bridge in the DC- DC section. GaN transistors in the topology reduce the transistor voltage stress by half compared with silicon or SiC devices. The design also allows measurements down to 1 mV,” said SamWong, vice-president and general manager for battery management solutions at TI. MicroNova says the simulator provides a cost-effective and safe solution for performing tests on BMSs, and simplifies and accelerates their development. The fact that CMC simulation on a economical 650 V GaN chips to be used for an 800 V design, leading to the reduction in the bill of materials. TheAC-DC stage has a peak efficiency ofmore than 99%, while theDC-DC stage has a peak efficiency of over 98.5%. The higher switching frequency allows smaller inductors to be used, reducing the inductor value by 80%and the volume of the inductors – amajor part of the volume of the design – by 75%. The design has an improved thermal performance by using an insulated metal substrate in the printed circuit board. This is combined with the design’s higher efficiency to reduce the complexity and cost of the cooling system’s design. It also helps reduce the overall size and HiL simulator can easily be combined with actual cell module controllers also reduces the cost of the HiL system. Simulating CMCs minimises changeover times and downtimes on HiL simulators, saving test and simulation time. “Setting up a HiL with real CMCs is complex, because it requires simulating the actual cell voltages of the battery as well as the temperature sensors,” explained Detlef Naundorf, product manager at MicroNova. “High overall voltages are generated in the HiL when emulating high-voltage batteries, increasing complexity in terms of reliability and hence the costs involved. The simulation of the cell module controller chips acts as a countermeasure to this. “At the same time, the NovaCarts simulator can be used as a standalone solution for software development and testing. It’s also easier to recreate and test fault situations than with a real-life set-up.” weight of the OBC, freeing up space and weight that can be allocated to other areas of an EV’s design. SIMULATORS CHARGING The cell module controller simulator can handle up to 35 BQ79718-Q1 devices from TI The design has AC-DC and DC-DC efficiencies of more than 99% and 98.5% respectively