Wireless Charger for Micromobility

Wireless Charger for Micromobility



REASONANCE, developer of wireless power transfer technologies, has already implemented several novelty products in WPT space, one of those was a wireless TV which made big news at CES2021 and CIIE2022 in Shanghai.

The company’s product portfolio has now been enhanced with a wireless charging system for e-scooters. The system is completely ready for commercial use and has already caught the interest of some large e-scooter sharing operators.

Here is the schematic diagram of the offered solution (see Figure 1). The transmitter unit is located on the ground and includes the following elements:

– The alternator which is powered from 220V AC mains and generates the alternating voltage to control the transmitter coil;

– The transmitter coil which generates an alternating electromagnetic field.

The receiver unit is mounted on a scooter and includes the following elements:

– The receiver coil which absorbs EMI from the transmitter coil;

– The AC/DC converter generating the DC voltage from the AC voltage supplied by the receiver coil. The DC voltage from the converter’s output is transmitted to the scooter’s battery or charge controller.

Figure 1. Wireless Charging System for E-Scooters

When designing WPT systems operating at low magnetic resonance frequencies (150kHz– 200kHz), we prioritize not only high efficiency of the solution, but also smaller size and lower cost of such systems. The low frequency range of the system makes it possible to reduce system’s cost and complexity by eliminating the need for resonant amplifier circuits and high-speed electronic components used at higher frequencies. Yet still, thickness of the receiver coil mounted on the bottom of the scooter remains to be its critical parameter, as it’s often made of metal and requires ferrite shielding, which not only adds weight to the unit, but also increases the cost of the product. To ensure inductance of such rating, the prevalent geometry of flat coils will require a large area of ferrite shielding. On the other hand, classic solenoids are not an option either as they have greater thickness. The REASONANCE system is compact and highly efficient due to its unique flat solenoid design. That enables operation close to the metal surface of the scooter deck and ensures high coupling coefficient in any case: either when a scooter is accurately positioned on the charging platform or not (angular misalignment). Furthermore, the proposed design ensures localization of the electromagnetic field precisely under the bottom of the scooter, which makes it safe for users.

wireless charger for micromobility

Power transfer efficiency is 95% (coil-to-coil)
This is one of the highest rates among other wireless systems.

No heating of the transmitter unit, which means:
• No cooling system is required
• The transmitter unit is very compact and thin
• The system is very durable and safe
• The system is low-cost and simple as it doesn’t require extra components (e.g. for cooling down)

Energy loss is minimal, so almost all the power goes to the device charging and functionality.

– Easy installation
It takes only 2 clicks to integrate the charging module and it doesn’t alter scooter’s dimensions or looks. The receiver unit is fitted in place of the original bottom using a single screwdriver and a single cable connection with the possibility of using the original charger retained.

Xiaomi Mi Electric Scooter Pro was used to build the first models, but the system is versatile and can be easily adapted to any other model of a similar design.

– Engineering and design
All the system components are combined in one module that is integrated inside the scooter footboard. There are no vulnerable or any electronic parts placed outside / on the steering wheel, etc. No wearprone components, which ensures durability and safety of the system.

– Compact size
The receiver unit is only 7 mm thick and doesn’t affect scooter’s dimensions or clearance. The transmitter unit is only 5 mm thick. Also, the transmitter unit can be seamlessly built into pavement without any platform (unlike bulky systems by other companies).

wireless charger for micromobility

REASONANCE scooter refit — $20 USD, transmitting system cost — $250 USD.

The REASONANCE system offers a number of advantages as compared to wired charging:

For consumers:
• It’s quick and easy — scooter starts charging automatically once parked on a charging station
• It’s safe — no wires, plugs or batteries

• Charging speed equal to wired charging
• Designated areas for parking where you can always find a charged scooter to ride

For e-scooter sharing operators:
• Lower operating cost thanks to cheaper servicing and logistics; no battery swap needed
• Higher revenue (e-scooter always in operation) and shorter payback period
• Higher safety (human factor eliminated)
• Higher scooter durability as there is no need to replace batteries or regularly take them for
• Extended battery life
• Easy to integrate and activate charging station
• Vandal-proof charging stations
• Low cost of scooter refit

wireless charger for micromobilityFor cities:
• Better planning and organization of micromobility parking areas, less chaos
• No need for service vehicles that transport batteries or scooters for charging, hence less traffic chaos, greater safety on roads and in pedestrian zones
• Charging station can be mounted on any surface or even built into pavement
• The system is rain and snow-proof
• The system is powered by the mains and/or by solar panels
• The system can transmit data on power consumption and charging stations status to the cloud

This technology can also be implemented in other products. For instance, our current portfolio of ready-for-market products includes a wireless TV mentioned above, demonstrating the following characteristics: 250W; 250kHz; 95 %.

REASONANCE is exhibiting at booth 10 at the The Wireless Power Technology Conference and Expo (WPTCE), in San Diego in June. We’ll be happy to present our wireless products – wireless e-scooter charging system and wireless TV – to the expert and business community.


Wireless Power Technology Conference & Expo

Wireless Power Technology Conference & Expo

Wireless Power Technology Conference & Expo
San Diego, CA | June 4-8th

WPTCE is the largest event in the world for wireless power research and industry engagement, covering a wide range of topics, applications, frequencies, and power levels. The event, formerly known as Wireless Power Week, combines wireless power school, workshops, conference technical and panel sessions, keynote speakers, an Industry Expo and a design competition. With five days of programming, two days of exhibition and over 400 attendees, this is the premier global event for the wireless power industry.

The 2023 Conference & Expo will be hosted at the Westin Bayview in downtown San Diego, CA from June 4-8th. 

Early bird registration is available until May 1st!


For information about sponsorship and exhibition opportunities at WPTCE, please contact WPTCE’s Industry Expo Coordinator at +1 720.224.4923 or trish@akamaistrategy.com. For general event inquiries, please email ieee.wptce@gmail.com

RF Wireless Power to Revolutionize IoT

RF Wireless Power to Revolutionize IoT

The New AirFuel RF Standard enables Mass Adoption and Interoperability of Over-the-Air, At-a-Distance Radio Frequency Wireless Power Technology

There is exciting news on the advancement of RF wireless power transfer! AirFuel™ Alliance, a global coalition of innovative companies working together on next-generation wireless power technology and standards, announced the release of a global interoperable standard for RF wireless power transfer in January. 

AirFuel RF technology creates a WiFi like experience for wireless power. AirFuel RF uses Radio Frequency waves to transfer energy wirelessly from a few centimeters up to a few meters, enabling charging and powering of multiple devices simultaneously within a three dimensional range, and delivering true freedom of movement. Of course, regulatory considerations limit the maximum power that can be transferred, and the energy received decreases with distance from the transmitter.

Given the advances in low power computing and communication technologies, and the availability of integrated circuits, it is now possible to build battery free IOT sensors for numerous applications, such as ESLs, industrial IoT devices, or temperature and humidity sensors in-home.

AirFuel RF In-Home Applications

AirFuel RF In-Home Applications

While it may not seem like a big deal, let’s think about the impact of the technology. 
  1. Reducing or eliminating e-waste – it is now estimated that over 3 billion batteries every year are discarded (and we suspect most of these end up in landfills) and the volume is increasing;
  2. Removing the hassle and expense of replacing batteries; and
  3. Eliminating the expensive and time consuming process of rewiring with changing layouts at a retail store, a factory floor, or even at home. 

And BTW, this technology has matured rapidly and is coming to market faster than most people realize. Energous has built tiny chips needed to build RF power transmitters. Atmosic, a partner of Energous focused on energy harvesting, has built chips that go into receivers. With reference designs available for both transmitters and receivers, product integration is well on its way. 

Availability of the standard provides the foundation for multi-vendor interoperability between transmitters and receivers. This is necessary to enable large infrastructure deployment and market growth.

The dream of wireless power at-a-distance has remained stubbornly difficult to deploy at scale, leaving consumers wondering when the wireless experience of their dreams might come to life. But with the release of AirFuel RF, the future of uncoupled wireless power is looking bright – and also green!

To help support the mass adoption of RF energy harvesting, AirFuel Alliance will offer a half day workshop in June at the largest wireless power event in the world, WPTCE . Accelerating demand in the market requires standardization, and AirFuel is leading the way. 

For those interested in exploring productization, an evaluation kit offered by Airfuel Alliance Board member, Energous, can be requested HERE. And to learn more about the AirFuel™ RF standard, UnWired readers can visit airfuel.org

Workshop on RF Wireless Power

Workshop on RF Wireless Power

For Engineers and Product Designers, there will be a half day training program on AirFuel™ RF technology to learn how to integrate wireless power with spatial freedom into your products. Integration and Deployment of RF Wireless Power in IOT Sensors Hosted at WPTCE on the closing afternoon of the conference.

  • Date: Thursday, June 8th
  • Time: 1-5 pm
  • Cost: $300 USD
  • Registration will launch soon on the WPTCE website!
  • To reserve your spot, email tommy@airfuel.org and we will notify you when registration is open.
Workshop on RF Wireless Power

Image Courtesy of AirFuel Alliance


  1. AirFuel RF Introduction
  2. Overview of AirFuel RF Specification
  3. Communication between Transmitters and Receivers
  4. Regulatory and Safety Considerations
  5. RF Power Transmitter Design (TX)
  6. RF Power Receiver Unit (RX)

Explore the WPTCE Website.

APEC 2023 Debrief

APEC 2023 Debrief

GaN was the Buzz of the Power Electronics Conference this Year

It was another jam-packed week at the Applied Power Electronics Conference (APEC), hosted in Orlando last week. The annual event focuses on both practical and applied aspects of the power electronics business, and a crowd over 3,000 strong made 2023 a great post-pandemic foray into the power electronics industry.

Some of our key takeaways from APEC this year include:


  1. It’s all about Gallium Nitride (GaN). 
    • GaN technology has been a hot topic at APEC for the past several years, and 2023 was no exception. GaN is driving the trend to higher frequency power electronics and systems, helping to reduce system size and power new experiences such as spatial freedom for wireless power. GaN applications featured include consumer electronics, data-center servers and power supplies, renewable energy systems, industrial motors and automotive electronics.
    • Dr. Tamara Baksht, CEO & Co-Founder of VisIC Technologies shared a plenary session presentation titled, “GaN for EV PowerTrain: Breakthroughs and Challenges,” discussing the successful development of a three-phase GaN-based inverter reference design and merging two buzz-worthy subjects – GaN advances and electric vehicle emergence. Wireless charging for EVs is a big piece of the EV infrastructure equation as wide-scale adoption takes hold.
    • GaN Systems previewed its GaN-Based 800V Onboard Charger for automotive applications at Booth #822. The charger combines a flying capacitor multilevel structure with high performance GaN switches, increasing power density and reducing overall BOM cost by as much as 15%.
  2. The stars are aligned for batteryless IOT sensors that last a lifetime.
    • Patrick Chapman, Vice President of Electrical Engineering at Redwood Materials, examined the issue of recycling batteries in a plenary session presentation on “Recycling, Refining, and Remanufacturing Battery Materials.” His speech not only highlighted the need to better manage battery recycling and e-waste, but also eliminate batteries altogether through the deployment of wireless power technologies.
    • Steve Statler of Wiliot, an expert in Bluetooth technology and intelligent ambient IoT, spoke at the Wireless Power Industry Showcase about building postage stamp size IoT sensors – IoT Pixels –  that feature RF power harvesting as the only energy source. 
  3. The all-electric driving experience is going mainstream.
    • The Genesis GV60, an all-electric vehicle crowned a 2022 IIHS Top Safety Pick, delivers striking design and intuitive personalization. The GV60 is coming to the US market soon and is shipping with wireless charging. 
    • In tandem with an APEC appearance by Milisav Danilovic, Senior Principal Scientist, R&D and Power Electronics Lead, WiTricity announced that it is partnering with ABT e-Line to bring wireless EV charging to the streets of Europe.
  4. Power electronics engineering education is necessary to take the industry forward.
    • The important issue of educating the power electronics workforce was top of mind. Robert Erickson, a Professor in the Department of Electrical, Computer and Energy Engineering at CU Boulder, discussed the development of a MOOC (massively open online course) degree program, which emphasizes Power Electronics and Embedded Systems Engineering and is tailored to working professionals.
    • Katherine Kim, Associate Professor of Electrical Engineering at National Taiwan University (NTU), talked about the impact of public educational videos, using the example of IEEE PELS, which is building up IEEE Educational Videos on Power Electronics (PELS Tube), peer-reviewed videos by power electronics experts available to all.
    • With wireless power adoption growing by leaps and bounds, it is crucial that our industry follow in the steps of other academic, trade and standards organizations and deliver education to train the workforce of the future in wireless charging and wireless power technologies.
The annual event focuses on both practical and applied aspects of the power electronics business, and a crowd over 3,000 strong made 2023 a great post-pandemic foray into the power electronics industry.

Image Courtesy of APEC / IEEE