It is not only storage capacity that grows to make this happen. The drives and servers also need regulated, guaranteed power to operate optimally. Uninterruptable Power Supplies (UPS) are an essential element of this solution, not only cleaning and conditioning the incoming electrical supply but also providing up-time during any power outages. One of the key measures of quality is efficiency, since any wasted energy is ejected as heat and such excess heat has to be removed by the data center’s air-conditioning system. With quality power conversion systems already regularly lying above 90% efficiency, innovative approaches are required to achieved every next percentage point of improvement.
In the power conversion circuits of typical UPS systems, there are two primary causes for switching losses. The first is the reverse recovery charge (Qrr) stored in the junction of the freewheeling diodes. The second occurs due to the charging of the switching transistor’s internal parasitic output capacitance (Coss).
An approach known as Synchronous Reverse Blocking (SRB) uses a second power transistor in series with the primary power transistor to block the reverse current through its freewheeling diode. Additionally, a silicon carbide (SiC) diode, which has an extremely low reverse recovery charge, is placed in parallel with these two series power devices. This method almost eliminates the impact of Qrr.
Toshiba has further refined this technique with their patented Advanced-SRB (A-SRB). This approach additionally pre-charges the parasitic output capacitance of the primary power transistor during the dead time of the bridge circuit, before the complementary switch of the bridge is being turned on, effectively reducing the impact of Coss by orders of magnitude, therefore significantly reducing the associated losses. As a result, an A-SRB inverter can deliver an efficiency comparable to what can be achieved utilising Wide-Bandgap devices. By utilising A-SRB, an improvement of up to about 4% over a comparable superjunction-based solution may be achieved.
To find out more about how A-SRB gate drivers such as the T1HZ1F can be used to implement efficient power conversion solutions, take a look at our latest whitepaper: