­PCIM News - Inverter Reference Design Ready for the Road

There are many types of electric vehicle on the road at the moment. However, the majority of these have been designed by high-volume manufacturers. These manufacturers have many resources on hand to build their new electric powertrains from the ground up. As they purchase large numbers of the latest products for their designs, their suppliers are also keen to provide even more resources to assist in designs. However, there are many other manufacturers in the e-mobility market that make lower volume designs that don’t have access to those resources.

The manufacturers of vehicles that sell in smaller volumes, such as buses, HGVs, heavy machinery, sports vehicles, or even cars and planes, would also like to electrify their own vehicles, but these smaller manufacturers have few electrical engineers on hand to produce new designs. The move from silicon solutions to SiC has made the change to electrical power even more difficult by introducing more complex control, faster switching and higher levels of EMI. To design a working SiC solution requires not just power engineers, but also engineers highly experienced in hardware and software design for embedded systems. Most SiC device makers provide reference designs to make their devices easier the integrate, but it still requires major time and effort to transform that reference design into a fully working production design and tune it for maximum efficiency and performance. Time-to-market is of the essence for these smaller companies to maximize their profit.

CISSOID saw a gap in the market for a more complete reference design and the company developed a solution that contains all of the components necessary to build a complete high-performance electric motor traction inverter with very little work. The first generation reference design proved successful, and the company has used this year’s PCIM exhibition to launch the second generation of the design. The original Bench-Top Inverter Reference Designs were intended mostly for laboratory and bench-based motor testing. The latest generation EVK-PLA1060 On-Board Inverter Reference Design was developed to offer a solution that is far closer to being production-ready. It can be immediately integrated into vehicles that are about to undergo in-vehicle and field testing, further reducing the time required for system development.

The On-Board Inverter Reference Design includes all of the major hardware and software elements that are required to make testing and evaluating an e-mobile inverter design as easy as possible. The SiC Inverter Control Module, a choice of 3D printed liquid cooler and the DC-link capacitor, a compact EMC filter and current sensors are included. The SiC Inverter Control Module itself consists of CISSOID's SiC power module, the gate driver board, the control board and application software. The compact and lightweight solution is built around CISSOID’s 3-Phase 1200V SiC MOSFET Intelligent Power Module, which is highly integrated and modular with a SiC-optimized gate driver. It has on-resistances from 2.53mΩ to 4.2mΩ and a maximum continuous current from 340A to 550A. The housing is designed for high reliability and is available with either a pinfin heatsink or a flat baseplate. 

Figure 1 - CISSOID’s 3-Phase 1200V SiC MOSFET Intelligent Power Module

The control system uses Silicon Mobility’s OLEA T222 FPCU (Field Programmable Control Unit), which includes dedicated e-motor control programmable hardware. The application-specific processor accelerates response times to critical events, off-loads work from the processor cores and enhances functional safety. The control board designed around the FPCU sits on top of the power module and CISSOID’s gate driver board below it.

Describing how the programmable hardware helps, Mike Sandyck, Marketing Director of CISSIOD said, “The processor is specifically designed for motor control. It contains an advanced motor event control unit - programmable circuitry telling the system how to react to certain motor events. This hardware real-time processing of events is completely separate from the main Arm-R5 core, allowing the core to react faster than a processor that has to do everything in software. This lets us react in microseconds instead of milliseconds, which, for safety reasons, is very important.”

The programmable hardware of the T222 processor enables fast control loops and high switching frequencies, and when combined with OLEA APP - T222 INVERTER control software, allows advanced optimization options, including dead-time compensation and advanced modulation. The solution is fully configurable for use with different e-motor types. Both the OLEA T222 processor and OLEA APP - T222 INVERTER software carry ISO26262 ASIL-D and AUTOSAR 4.3 certification, while the ISO26262 certification of CISSOID’s ICMs is currently in progress.

Figure 2 - The EVK-PLA1060 On-Board Inverter Reference Design

The EVK-PLA1060 On-Board Inverter Reference Design is capable of providing a power range of 100 to 350kW, on a 100 to 850V operating bus voltage and offers highly efficient operation, even at low loads.

www.cissoid.com