During the trade show PCIM 2010 which took place from May 4th to 6th in Nuremberg, the power semiconductor manufacturer Semikron presented its second generation of power electronic systems: SKAI. With power densities of 20 kVA/litre, SKAI is supposed to provide significant size reduction compared to the other standard products available. The systems are designed to operate with supply voltages between 24V and 850V and with output power ratings between 10 kVA and 250 kVA.
“With SKAI 2 we present the most compact power electronic systems for hybrid and electric vehicles for use in the agricultural and construction industry, materials handling and battery-powered vehicles of any kind”, states Peter Beckedahl, Manager Concepts & Application at Semikron, who claims that “20 years of experience in the development of hybrid and electric power systems for use in forklift trucks, buses and agricultural equipment and machinery have gone into the development of our SKAI modules”. The company achieves about 10 % of its revenue with components for electric cars.
There are three versions of SKAI available, which have been developed in order to support the latest automotive and system qualification standards. Customers can choose between systems supplied as
• standard modules with low-voltage MOSFETs
• high-voltage IGBTs
• with the topology of single, dual and multiple inverters
SKAI systems are also developed to meet individual customer specifications. Semikron is a single-source supplier that covers everything from feasibility and proof-of-principle studies, the development of optimum system architecture, to electrical and mechanical simulations, end qualification, and complete-system series production. All SKAI 2 modules are fully qualified using analysis such as highly-accelerated life testing (HALT) and end of component-life testing, with full failure-mode effect analysis studies conducted at all critical points of the design cycle, to ensure that they are in line with relevant automotive standards.
The high-voltage SKAI 2 is available as a water-cooled 600/1200 V IGBT inverter system, and has been optimised for use in applications such as full-electric cars, plug-in hybrid cars and electric buses. This system is based on the established sintered, 100 % solder-free SKiM93 IGBT modules, features a polypropylene film DC-link capacitor, driver electronics, a latest-generation DSP controller, EMC filters, and current, voltage and temperature sensors, and comes in an IP67 module case. Communication with the vehicle master controller goes over CAN. These systems are designed for outputs of up to 250 kVA.
The low-voltage SKAI 2 is available as an air-cooled or water-cooled 50/100/150/200V MOSFET single and dual inverter system that is used mainly in fork-lift trucks and other materials-handling applications. These systems are suitable for a motor output of up to 55 kVA. They incorporate many of the same features as the IGBT-based systems and thereforethey behave in the same way, use the same core control system, I/O connections, and the same system structure.
The third type of SKAI 2 platform is a multi-converter box. These systems are also housed in water-cooled, IP67-protected cases and communicate with the vehicle master controller via a CAN bus. The signal interface features analogue and digital I/Os to allow for the connection of a wide variety of sensors, such as temperature sensors and resolver inputs. A typical multi-converter system includes a three-phase 40 kVA active front-end converter, a three-phase 20 kVA drive inverter, a three-phase 10 kVA drive inverter, and a 14 V/300A or 28 V/165 A DC/DC converter.
All picture credits: Semikron