Toshiba Electronic Devices & Storage Corporation has announced their participation in PCIM Europe 2018 where they will showcase their comprehensive portfolio of power semiconductor devices and solutions. Included on the booth will be several extensions to existing product lines as well as some completely new products and technologies.
One example of the technologies to be featured by Toshiba is a technique to control switching losses in power converters based on half-bridge circuits. Synchronous Reverse Blocking (SRB) adds a second switching transistor in series with the main switch to block the reverse current in the associated freewheeling diode.
This second switch must be synchronized with the main switch so that reverse current is passed through a parallel silicon carbide (SiC) Schottky diode. This diode has a high breakdown voltage and an extremely low reverse recovery charge so that the effect of Qrr on switching losses is significantly reduced.
With Advanced SRB (A-SRB1) the losses caused by recharging the output capacitance of the main switch are significantly reduced by pre-charging it to a lower voltage. The output capacitance COSS strongly depends on the drain-source voltage VDS. When this is increased from 0V to 40V the capacitance is reduced by a factor of about 100.
During turn-on, this voltage dependency causes the main portion of the charging current to flow for low VDS. However, in a half-bridge configuration, a low VDS across the switch being in off-state means a high voltage across the switch turning on, leading to high turn-on losses due to the charging current peak.
If COSS (Q1) of the switch remaining in off-state, is pre-charged before turn-on of the other switch of the half-bridge (the low-side switch in our example) most of the charging current does not flow through the transistor turning on and thus cannot contribute to turn-on losses. The pre-charging is performed by an additional voltage source, which is realized by a charge pump in the gate driver IC.
Based on the A-SRB technology, Toshiba has developed a system solution for PV inverters with an output power of up to 5kW. It consists of four main components:
- The inverter bridge with A-SRB technology
- One MCU for controlling the entire system
- Two analog front-end ICs (AFE) for controlling the DC/DC converter input stages as well as the output inverter.
In addition to the efficiency gains achieved by A-SRB, the highly-integrated AFE ICs contribute to a compact, cost-optimized inverter system. Toshiba's A-SRB is only one of the technologies to be featured at PCIM 2018, others will include:
- The latest generation of 30-100V class LV MOSFETs delivering best in class efficiency
- 600V planar MOSFETs (PIMOS IX) with low noise, high efficiency & avalanche ruggedness
- The latest automotive MOSFETs line-up
- Automotive photocouplers with IC-, transistor-, photovoltaic- and MOSFET-output
- Photocouplers for high-speed data transmission, gate driving, and isolation amplifiers
- Photorelays for mechanical relay replacement
- Motor control solutions for improved efficiency and higher precision
Toshiba also anticipate unveiling two new 40V N-channel MOSFETs designed specifically for demanding automotive applications during the show.
PCIM Europe 2018 runs from 5th to 7th June 2018 in Nuremberg, Germany and Toshiba can be found in Hall 9, on Booth 301 where their technical team will be available to discuss new and existing products and answer customer questions.