Technology in Wireless Power Transfer (WPT)
Wireless Power Transfer (WPT) is a technology to transfer power between two objects without physical contact. WPT is commonly used in consumer products such as mobile phone chargers. The technology can also be useful in commercial applications, specially in high power cases. But technology needs to be further developed in the areas of efficiency, compactness, costs, and controllability. Etrixa continues to develops solutions to meet such requirements for high power WPT.
Topologies and configurations
We select coil topologies and system configurations based on system efficiency and costs in the target applications. The thermal and mechanical aspects are more important in selection of topologies for high power uses. Optimized modular design enables upscaling for very high power in parallel configurations.
Boosting of power transfer
With increase of air gap between the objects, more magnetic energy needs to be injected in the air space. Compensation circuits with high-speed AC capacitors are needed to excite such magnetic field with limited capacity of the transmitter and receiver converters.
Loss minimisation
To achieve as high as possible efficiency, new devices and materials are used in our solutions. The optimal designs of coils, compensation circuit, and converters are also important to consider electromagnetic, thermal, mechanical, and manufacturing aspects.
High frequency conversion
In order to transfer more energy with the limited size of coils, faster turnover of the magnetic energy is the key method. To achieve the high frequency, high-speed semiconductor switches, low AC loss cables, low loss core materials, and control method with high bandwidth are required.
System optimisation
WPT systems include many components and their strong interactions. System optimisation and balance are important for high performance and cost-effective systems. The maximun electromagnetic energy conversion within the defined space and under thermal and mechanical boundary conditions.
Control for uncertainties
WPT systems are required to work under uncertainties and variations. They need to handle misalignment of coils, variation of air distance , and change of voltage levels. Advanced control should be implemented to keep stable power flow between the transmitter and the receiver and deal with unexpected happenning.
Technology in high power converters
Modern power electronics plays important role in motor control for not only transportation and also other combustion driven equipment. Wide bandgap semiconductors such as SiC and GAN devices enable us to develop high performance converters. Our focus is on DC/AC inverters with 800V DC voltage for power range of 5 – 500 kW. The general objective is to achieve high efficiency and high power density. These inverters can be operated in 1-30 kHz switching frequency in motor drives for vehicle applications and quadratic load applications such as marine propulsion and heavy-duty cooling fans.
- Three-phase inverter: power up to 250 kW, efficiency up to 99 %;
- Double three-phase inverter with shared DC links and housing: power up to 500 kW.
Wide band-gap (WBG) semiconductors
We have built our inverters with WBG devices, specially 1200V SiC chips and power modules from the top semiconductor producers. The voltage level matches the requirements of heavy-duty vehicles and equipment we want to electrify. These devices combined with other technologies give us freedom to design high-power inverters in small size. The higher speed switches enable much faster energy conversion cycles, which is crucial in some demanding systems like high power wireless charging and high power drives.
Advanced DC-link
With use of modern SiC power modules, DC capacitors of the DC-link become a dominant part in an high power inverter. Size reduction of these capacitors is actual challenge for compactness of the whole inverter. Our solution can significantly reduce the size of these capacitors and extend the life time. Another critical component of a DC-link is the DC busbars which is contributor to stray inductance and over shooting in switching phase. Our busbars is designed for minimum stray flux and thermally well managed.
Adaptive control
To reduce the losses and keep long lifetime, adaptive control method is developed to control the commutation of the semiconductors and internal settings dynamically. Optimisation is not only in design phase but also in operation phase. It is specially important for commercial drivetrains. Balance between output performance and component degradation is kept according a predefined strategy. Long life-time of expensive equipment contributes to high ownership value and societial sustainability.
Technology in modern electrical machines
Electric motors convert electric energy to mechanical energy, that are considered as the hearts of the electric vehicles. Modern electric motors are new types of electrical machines with new structures, new controllers, new materials, and manufacturing methods to meet the requirements of high performance and low costs. Our focus is on high performance electric motors without using rare-earth materials. Our speciality is brushless (wireless) excitation systems that can be used for Electrically Excited Synchronous Machines (EESM) for electric vehicles and superconducting electric motors.
EESM (high performance, no magnets)
Electrically Excited Synchronous Machines (EESMs) become a potential alternative to replace Permanent Magnet Synchronous Machines (PMSMs) in case of lacking resources of rare-earth materials. Our EESMs are optimally designed and able to reach the same volumetric torque density as rare-earth based PMSMs. The special feature of EESMs is its controllable excitation (magnetic fields). This enables high efficiency in partial load conditions and advoiding no-load magnetic losses.
Brushless excitation system
Brushless Excitation System (BES) are used to transfer excitation power to rotors wirelessly in rotating machines. It can replace the slip-rings/brushes in the excitation circuit of EESMs. Our BES can deliver power up to 5 kW under rotation speed of 18000 rpm. The secondary current can be designed for different applications, e.g. 300 A for superconducting motors. The efficiency of BES can reach 90-95% DC-DC.
Other electric motors
High performance PMSMs for traction applications, marine propulsions, and heavy-duty fan drive. Synchronous reluctance motors for self-starting or converter driven.
Technology in electrification of drive systems
Electric drive systems have potential to replace combustion driven systems and hydraulic serve systems in many applications. We can extract mathematic models for different components such as motor, converter, gearbox, battery and loads. We can also model the whole drive systems for system simulations.
System modelling and simulation
Component modelling includes electric parameters and losses for components (motor, converter, gearbox, battery and loads). Co-simulation to quantify the system performance and fault handling. System modelling can also be applied to investigation and analysis of new electric system in replacing conventional drivetrains.
Machine simulator and Power HIL
To verify the control hardware and control methods, Hardware-In-the-Loop (HIL) can be used without need for hardware for the full physical systems. To verify an inverter, Power-HIL, or called machine emulator, can be utilized, in which the physical electric machine is represented with inductors/transformer and second inverter. The machine model is stored in the secondary inverter.
System design and configuration
The system to be electrified should be analysed in global and local functionalities. The possible replacements of each components should be investigated based on the various electric components. The electric components can be designed and evaluated via numerical analysis methods such as FEM, circuit simulators, and function simulators. The whole electric system should be configured and verified.