Broadly speaking, energy storage is the gathering of energy produced at one time, to be stored and used at a later time. For energy storage systems (ESS) there are two major use cases: creating utility-independent, solar-powered homes (residential ESS) and - on a larger scale - utilities supplementing generated power during periods of high demand (utility scale ESS).
Older generation residential solar energy systems are tied to the utility power grid via inverters which convert power from solar panels to AC electrical power during daylight hours. Marketable excess power might be sold back to utility companies. However, during the hours of darkness the end user is relying on the utility's electricity supply. Utility companies are aware of these limitations and adjust their pricing models accordingly. Residential customers pay based on so called "time-of-use" rates which are higher when solar power is not available.
This is where behind-the-meter ESS comes into play. The electricity that is collected via solar panels charges batteries - the energy is stored. When using these batteries with an inverter, the demand for AC power can be fulfilled at any time.
For residential ESS, the two main system-coupling topologies, which usually come along with PV installations, are the DC-coupled and the AC-coupled.
In a DC-coupled system, the energy stored in the battery is boosted to a certain DC-bus voltage, usually in the range of 400 V. This system is directly connected to the DC line using a DC-DC converter - not converting DC to AC.
In the AC-coupled system, the stored energy from the battery is supplied directly into the AC grid. In this case, both a DC-DC converter and an AC-DC inverter are used.
Both systems must be capable of bidirectional operation - drawing energy from the battery and charging the battery with excessively produced power.
With the increasing number of battery variants and different ESS versions, engineers and designers are constantly confronted with the need for higher efficiency, power density, and reliability in their system designs. Three trends are foreseen that will have a major impact on how ESS designs will develop and how they will look in the future:
Infineon's renowned technology expertise and broad product portfolio for leading-edge ESS solutions ensure reduced design efforts, improved system performance, fast time to market, and optimized system costs.
For a single-phase, bidirectional AC-DC stage a recommended topology is the continuous-conduction mode (CCM) totem-pole boost converter. For a three-phase, bidirectional AC-DC system the ideal topology is the three-level, active-neutral-point-clamping (ANPC) converter. Both topologies require switches with a low-reverse characteristic body diode.
Infineon's offering: the newly launched, SiC-based CoolSiC™ trench MOSFET 650 V portfolio including the matching 2-channel galvanically isolated gate-driver IC, EiceDRIVER™ 2EDF9275F (coming soon). Experience the revolution in power conversion.
Being the result of a state-of-the-art trench semiconductor process, this new high-performance MOSFET series minimizes losses in the application and maximizes reliability in operation.
The use of IGBT discrete devices and modules for the power conversion stages limits the battery utilization to the weakest battery pack. The system keeps operating only until one pack reaches the minimum allowable charge level.
Infineon's offering: the market leading OptiMOS™ family - highly efficient, low-voltage power MOSFETs for developing modularly cascaded, multi-level architectures. Advanced control schemes balance the state-of-charge (SOC) of different batteries among all the packs in the system by placing a heavier load on those packs with higher SOC, while at the same time bypassing stages with a battery SOC dropping below the minimum level. Optimal battery utilization is achieved. Major advantage of the approach: enablement of 2nd life of batteries, i.e. the environmentally friendly use of recycled batteries.
Associated partners of Infineon are STABL and Mobius - click on the names to discover the jointly developed multilevel energy storage turnkey solutions for high power consumption organizations:
During charging and discharging batteries must be monitored closely to protect against over- / under-voltage, inrush current, reverse current, and short circuits.
Infineon's offering for battery protection (download selection guide below): making customers benefit from
Monitoring cells in battery packs ensures operation within the safe-operating range. Various parameters, such as cell voltage, state of charge (SOC), state of health (SOH), and also the temperature have a decisive impact on the performance, safety, and lifetime of batteries. Cell balancing caters for even balancing between battery cells put in series.
Infineon's offering for battery monitoring: a general-purpose transceiver IC for multi-cell battery systems as well as a multi-channel battery monitoring and balancing system IC are currently in development. For updates get in touch with your trusted Rutronik experts.
Witness the top performance of CoolSiC™ trench MOSFETs 650 V with Infineon's latest simulation models.
EVAL_3K3W_BIDI_PSFB
3300 W, 54 V bidirectional phase-shift, full-bridge (PSFB) solution featuring 600 V CoolMOS™ CFD7 and XMC™ microcontroller
OPN: EVAL3K3WBIDIPSFBTOBO1
Infineon components:
This evaluation board represents a complete system solution for a 3300 W bidirectional DC-DC converter that achieves 98% efficiency in buck mode and 97% in boost mode. The EVAL_3K3W_BIDI_PSFB is a DC-DC stage with telecom-level output realized by a phase-shift, full-bridge
(PSFB) topology block with bidirectional capability. The board features CoolMOS™ CFD7 and OptiMOS™ 5 in a full SMD solution with an innovative cooling concept.
Target applications: telecom, battery formation power, industrial robotics
Features:
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EVAL_3K3W_TP_PFC_SIC
3300 W CCM bidirectional totem-pole PFC unit using CoolSiC™ 650 V, 600 V CoolMOS™ C7, and digital control via XMC™ microcontroller
OPN: EVAL3K3WTPPFCSICTOBO1
Infineon board components:
This evaluation board is a system solution for a bridgeless totem-pole power factor corrector (PFC) with bidirectional power capability.
The EVAL_3K3W_TP_PFC_SIC is enabled by Infineon's CoolSiC™ trench MOSFET and CoolMOS™ Superjunction power MOSFETs as well as isolated drivers and an XMC™ microcontroller.
Target applications are those requiring high efficiency (~99%) and high power density (72 W/in3), such as high-end server and telecom. In addition, the bidirectional power flow capability allows to address battery chargers or battery formation applications, too.
The integrated totem-pole operates in continuous-conduction mode (CCM) in both, rectifier (PFC) and inverter mode which also implements digital control on Infineon's XMC™ 1000 series microcontroller.
Target applications: high-end server, datacenter, telecom
Features:
Benefits: