Ditch the plug! Make wi-fi EV charging a actuality now!
Distinctive elements guarantee security, effectivity and reliability.
Think about an EV charging expertise that’s as seamless and intuitive as parking your automobile—simply “park, cost, and go.” For the end-user, the attraction is evident:
- No extra heavy cables
- No fumbling with connectors
- No publicity to doubtlessly soiled or broken charging gear
EV house owners envision pulling into their storage, a delegated parking spot, or a public charging station and effortlessly charging their car with out ever leaving the motive force’s seat. This comfort makes day by day charging extra user-friendly and enhances security by eradicating bodily connectors altogether.
Understanding this user-centric imaginative and prescient is essential for wi-fi EV charging system designers. By delivering environment friendly, dependable, and quick wi-fi charging, designers can unlock a game-changing profit that mixes ease, consolation, and peace of thoughts for EV drivers.
Whereas present wi-fi EV chargers can provide as much as 20 kW to cost batteries in 4 to 6 hours, future wi-fi chargers will ship 100 kW and be capable of improve battery cost state by 50 p.c in beneath 20 minutes.1
Wi-fi charging stations should be quick, protected, environment friendly, and dependable to speed up adoption.
This text explores the technical concerns and progressive approaches required to attain this expertise, guaranteeing wi-fi charging options meet efficiency and consumer expectations within the ever-evolving EV panorama. It presents 4 elements that tackle the important must create designs that guarantee charger circuit safety, security monitoring, and quick, environment friendly energy supply.
Wi-fi charger description
A wi-fi charger is an AC-AC converter that converts 50/60 Hz energy to energy within the frequency vary of 130 kHz. Resonant frequency depends upon topologies and Energy semi conductor know-how (Si/SiC/GaN). Energy supply may be as much as 20 kW. Determine 1 illustrates a wi-fi charger and its load, the EV. The main energy and management circuit blocks within the charger and the car are additionally outlined.
Security and reliability concerns embody overcurrent safety, overvoltage safety, overtemperature, and floor present monitoring. Optimizing effectivity requires designing with low energy loss elements. Determine 2 illustrates elements that present circuit safety and excessive effectivity for the circuits of a typical wi-fi charger design. The sensors provide temperature monitoring and enclosure entry safety.
Figures 3 and 4 present an instance wi-fi charger in a extra detailed block diagram. The adjoining desk in Determine 3 lists the elements that equip the charger with safety from electrical hazards. Determine 4 primarily reveals the elements that produce effectivity and significant sensing.
Circuit safety and security elements
The Enter Safety circuit homes the principle overcurrent and overtemperature safety elements. Really helpful elements embody a excessive present fuse for the facility supply circuitry and a fast-acting fuse to guard the low energy Auxiliary Energy Provide and the management circuitry. A metallic oxide varistor (MOV) in collection with a gasoline discharge tube absorbs overvoltage transients. Overvoltage transients consequence from lightning which might induce a voltage surge on the AC enter traces. As well as, electrical masses switching on and off can induce AC line voltage surges.
A particular element that may seize parts of a voltage transient that has handed by means of the MOV and gasoline discharge tube is a transient voltage suppressor (TVS) diode. TVS diodes have decrease clamping voltages, and so they function a lot quicker than MOV gadgets. The particular diodes can guarantee safety of downstream circuitry. They’ll take in a one kA pulse and reply to a transient in beneath one nanosecond. TVS diodes can present safety from electrostatic discharge (ESD) through-the-air strikes of as much as 15 kV and from direct contact discharges as much as 8 kV. Bi-directional fashions and fashions which are lower than one tenth the dimensions of conventional discrete options can be found. TVS diodes can have axial lead or floor mount kind components. Determine 5 reveals a TVS diode and its practical diagram, utilizing the AK1-Y Sequence TVS Diode from Littelfuse for instance. This element will dispense the required safety from each ESD and different transients to keep away from injury to semiconductor circuitry within the wi-fi charger.
With techniques similar to wi-fi EV chargers, monitoring floor currents is important for the safety of personnel. The Earth-Fault Safety circuit performs the bottom present monitoring perform. Littelfuse affords new residual present screens for this circuit that detect each AC and DC floor fault currents. The brand new collection, the RCMP20 Residual Present Monitor Sequence for Mode 2 and Mode 3 wi-fi charging stations, affords the biggest present transformer aperture to assist larger AC charging currents. The residual present screens have delicate, typical journey thresholds of 4.5 mA DC and 22 mA AC. Moreover, the screens make the most of built-in conductors with larger cross-sectional areas to offer higher thermal administration and scale back the rise within the printed circuit board (PCB) temperature. The result’s a extra compact and dependable design that doesn’t compromise efficiency. As well as, the screens have excessive immunity to electromagnetic interference (EMI), which improves charger circuit reliability and minimizes false circuit journeys. The screens may be mounted both horizontally or vertically to permit designers flexibility to optimize area utilization. Determine 6 shows the fashions within the Residual Present Monitor collection. (View the video.)
Parts for maximizing effectivity and reliability
Techniques, similar to wi-fi charging techniques, devour a considerable quantity of energy. Optimizing a design for effectivity reduces energy consumption and utility prices and reduces warmth buildup. Lowered generated warmth lowers the inner temperature rise within the system and enhances system reliability. The usage of two elements within the energy supply circuitry can contribute to larger effectivity and better reliability. The 2 elements are gate drivers and SiC MOSFETs.
Gate drivers management the Energy SiC MOSFETs and the IGBTs within the Bridgeless, Vienna, or Enhance Rectifier and the Full Bridge, Resonant Excessive-Frequency Converter circuits. The drivers have separate 9 A supply and sink outputs, which allow programmable turn-on and turn-off timing whereas minimizing switching losses. An inner destructive cost regulator offers a selectable destructive gate drive bias for improved dV/dt immunity and quicker turn-off. The gate drivers decrease switching occasions with turn-on and turn-off propagation delay occasions of sometimes 70 and 65 nanoseconds. The everyday worth for rise time and fall time outputs is ten nanoseconds.
To make sure sturdy operation, the gate drivers have desaturation detection circuitry which senses a SiC MOSFET overcurrent situation and initiates a comfortable flip off. This circuit prevents a doubtlessly damaging dV/dt occasion. Further safety options embody UVLO detection and thermal shutdown. Determine 7 illustrates theLittelfuse IX4352NE SiC MOSFET and IGBT Driver IC, a high-speed gate driver with options that present dependable management of a SiC MOSFET.
Excessive-power SiC MOSFETs drive the facility transmission coils. Half-bridge packages have a Drain-Supply voltage of 1200 V and a drain present of as much as 19.5 A. Together with delivering excessive energy, the MOSFETs decrease on-state energy consumption with a typical RDS(ON) of a low 160 mΩ. SiC MOSFETs have low switching energy losses attributable to a typical low gate cost, brief turn-on, and turn-off delay occasions, and present rise and fall occasions.
A DCB-based remoted bundle improves thermal resistance and energy dealing with functionality. A complicated topside cooled bundle simplifies thermal administration. The Littelfuse half-bridge SiC MOSFET MCL10P1200LB Sequence, proven in Determine 8, yields excessive effectivity with superior packaging to cut back element rely and to optimize for prime reliability.
Collaborate with specialists for a dependable wi-fi charging resolution
Safety in opposition to electrical hazards similar to overcurrent, overvoltage, ESD, and overtemperature is crucial for guaranteeing dependable operation. The 4 really useful elements described within the previous paragraphs allow designers to develop sturdy, protected, and dependable wi-fi EV charging stations.
To develop a sturdy and environment friendly product, designers ought to contemplate using the element producers’ utility engineers to save lots of design time and compliance prices. The appliance engineers may also help with the next:
- Collection of cost-effective safety, sensing, and high-efficiency elements
- Data of the relevant security requirements
- Littelfuse can carry out pre-compliance testing to keep away from compliance take a look at failures and save on undertaking delays and added prices for a number of compliance take a look at cycles.
Collaborating with the element producer’s utility engineers and utilizing the really useful elements will assist to supply sturdy, dependable, and environment friendly wi-fi EV charging options.
To study extra about circuit safety, sensing, and energy administration options for wi-fi EV charging design, obtain the information, Supercharged Options for EV Charging Stations, courtesy of Littelfuse, Inc.
Contact Littelfuse for extra data on making your wi-fi charging system design protected, environment friendly and dependable.
References:
1L. Blain. World’s quickest wi-fi EV charger unlocks 100 kW parking spots. New Atlas. March 18, 2024.
