Renesas Adds IGBT Drivers with Micro-Isolator for Electric and Hybrid Vehicle Inverters

Renesas Electronics Corporation announced the development of the R2A25110KSP intelligent power device of isolated IGBT driver for use in electric and hybrid vehicle power inverters. Incorporating newly developed Micro-Isolator isolation technology exclusive to Renesas Electronics, the R2A25110KSP makes it possible to build more highly reliable and compact systems for today’s demanding automotive applications.

Inverters that drive the electric motors in electric and hybrid vehicles comprise a power module employing motor drive elements such as IGBTs and a control circuit block with electrical isolation between the low-voltage drive electronics and the high-voltage power electronics. The market growth of power inverters has driven power modules to become even more compact to reduce size, weight and overall cost of the system. Demand is growing for solutions that integrate the isolation elements and IGBT driver circuits to enable an even greater reduction in power module size to meet the ever-increasing push for lower cost and higher performance.

The R2A25110KSP has a built-in isolation feature called “Micro-Isolator,” an isolated signal transmission technology exclusive to Renesas that uses a coreless transformer configuration. Designed for automotive applications with severe ambient temperature conditions, this device has a rated channel temperature of 150°C (max.). The R2A25110KSP delivers fast switching capacity with low dispersion (meaning that the range of characteristic values is narrow), for improved efficiency in motor drive applications. In addition, capability of IGBT drive is two to four times better than that of comparable products (impedance in on state: 1.0 Ω max.), allowing direct IGBT drive without external transistors. This reduction in external components makes it possible to decrease the PCB footprint area and use a more compact inverter control board design.

IGBT devices are used in parallel as drive elements in inverter systems. In many HEV/EV applications, two IGBT devices are connected in parallel to drive a large capacity motor. Therefore, the inverter system should detect both the IGBT abnormal conditions such as over-current and/or over-temperature and avoid them. Conventional isolated IGBT drivers, however, have only one over-current protection and/or one over-temperature protection; this requires larger circuit board area. The R2A25110KSP integrates both methods, enabling protection for both IGBTs without increasing circuit area.

The IGBT chip temperature monitor circuit monitors the temperature of both IGBTs continuously and also feeds back the higher one to the MCU via Micro-Isolator. The temperature can be calculated from the duty ratio of the pulse.

Other functions that are integrated include active Miller clamp and soft turn-off. The active Miller clamp prevents false turn-on when an IGBT is in off state, and soft turn-off of the IGBT gradually when an abnormal state such as over-current occurs. This IGBT turn-off function can avoid an over-voltage spike across the IGBT caused by lead and wire inductances. These features result in a higher performance-to-cost ratio in terms of smaller system footprint, better performance and improved system reliability.

The first samples of the R2A25110KSP in 38-pin SSOP package will start at the end of April 2013, priced at US$5 per unit. Mass production is scheduled to start in the first half of 2015 at a level of 1 million units per month. Sample shipments of the R2A25112KSP intelligent power device for isolated IGBT driver in a 20-pin SSOP package are scheduled to start in December of this year.