Manufactured using advanced materials for to achieve reliability and low weight, the units are among the first working examples that are compact and light enough for use in an electric car.
“When an electrically powered vehicle is stopped, energy that can be regenerated into the propulsion system is created, because the motor itself acts as a generator,” explained Peter Duncan, managing director of Cressall Resistors. “This braking energy needs either to be put back into the power supply or dissipated as heat, if the vehicle’s battery is already full. Proposed EU regulations for electric vehicles will require brake systems with a continuous rating. This demand can best be met by using specially designed brake resistors.”
Cressall’s EV series uses a system that encapsulates and totally separates the resistor elements from the coolant. The construction also achieves maximum thermal conductivity and maximum electrical insulation. “Developing this product has required us to go back to first principles to find the materials that reconcile all of these issues,” continued Duncan.
The simple modular construction means Cressall’s EV resistors can be combined to handle any power inputs from 10kW upwards and voltages from 12V to 6kV. The coolant pressure is up to three bar and the coolant liquid can be water or water glycol, meaning that the resistors is suitable for any type of liquid cooling.
The new EV range has been extensively vibration tested and has no ambient temperature limits. Furthermore, the unit’s simple design means that it can be mounted wherever appropriate in the vehicle’s coolant system.
Cressall’s EV resistor range is one of the latest examples of the company’s commitment to advancing electrical braking technology. The Leicester based electrical firm’s resistors are used in regenerative and dynamic braking for locomotives, metros and mass transit systems, trams, buses, cranes, ships and oil rigs. They can handle the harshest environments with minimum maintenance and are used by major brands across the globe including the London Underground and EuroStar train network.
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