2nd Jun 2023
DG Innovate’s quest to develop electric vehicle (EV) drive systems that set new standards for power density, performance and reliability has been significantly advanced by the introduction of a novel cooling system. This facilitates efficient transfer and removal of heat from key drive components by immersing them in an oil with outstanding thermal and dielectric properties.
If high power densities combined with reliable operation are to be attained in EV drive systems, efficient and dependable cooling is essential. DGI provides this by immersing in oil not only the motor coils but also the power semiconductors used to control the motor. The oil is circulated continuously, and a key feature of the new cooling system is that the flow rate of the oil is dynamically controlled in real-time, ensuring optimum heat transfer in all operating conditions.
To achieve this, the oil flow rate is monitored along with the inlet and outlet temperatures of the motor and electronics chambers. The flow rate is dynamically adjusted to optimise cooling performance, taking into account the rate of change of temperature, the absolute temperature, the thermal capacity of the oil, and the efficiency of the radiator in dissipating heat to the atmosphere.
In addition to providing efficient and reliable cooling of all key elements of the EV drive, the DGI cooling system also delivers environmental benefits, since it intrinsically prevents condensation and, as a closed system, it releases no contaminants. A further benefit is that by immersing critical components in oil, the system provides them with a high degree of protection against mechanical shock, which is an ever present hazard when driving vehicles over rough terrain.
The improvements in cooling technology complement and enhance the highly innovative motors that are being developed by DGI. These feature a unique multiple parallel system architecture which effectively splits the torque-producing elements into a large number of segments.
This segmented design results in much enhanced fault tolerance, as the motor will continue to operate with only slightly reduced output if an individual segment fails, and it also allows the motors to be powered by inverters that are more efficient and more cost effective than those used with conventional motors.
