Improving the regenerative braking system of a mild hybrid vehicle

Problem. Mild hybrid vehicles are a good compromise in terms of price-quality ratio among hybrid vehicles. To reduce the cost and weight, as well as to increase the efficiency of recuperation of a mild hybrid vehicle, a new algorithm for the operation of the power plant engines in the city traffic mode is proposed. In the proposed vehicle, movement with an electric drive and a stopped ICE is replaced by uniform movement at a relatively low speed (40-50 km/h) on an asphalt road without a noticeable rise. The ICE idle mode is also excluded due to the start-stop system. Starting from a standstill and accelerating must be done on the ICE. In this driving mode, the service recuperative braking mode of the electric motor-generator is of great importance, in which a sufficient electrical load of the traction electric motor operating in the generator mode is important. The small capacity of the traction battery of the mild hybrid vehicle and the relatively high speed of regenerative service braking quickly lead to low efficiency of electric braking due to the reduced charging current of the low-capacity traction battery. Goal. The aim of the work is to increase the efficiency of regenerative braking. Methodology It is shown that in this case sufficient deceleration during regenerative braking will be achieved by connecting an active three-phase load for alternating current to the electric motor-generator. Results. An improved regenerative braking of a mild hybrid vehicle is considered. Excess recuperation energy is proposed for heating the internal combustion engine coolant. A theoretical justification is considered for why an active three-phase load of the electric motor-generator with heating elements in the internal combustion engine cooling system is required. A practical implementation of the technical solution is given, for which an electrical circuit of the recuperation system and a basic electrical circuit of the current control unit are developed. Originality. This study provides a comprehensive solution to the technical proposal in the patent.  Practical value. The results of this study are of value to mild hybrid vehicle developers. The knowledge gained contributes to the optimization of the regenerative braking process. This study supports the broader goal of accelerating the adoption of mild hybrid vehicles.