Method for controlling a vehicle's hybrid powertrain system on a surface with a low coefficient of friction

Abstract

Method (100) for controlling a hybrid powertrain system (12) of a vehicle (10) on a low-friction surface, wherein the hybrid powertrain system (12) comprises a traction control system (19), first and second drive axles (16F, 16R) each connected to a corresponding set of drive wheels (18), an internal combustion engine (15) connected to the first drive axle (16F), an electric machine (20) connected to the second drive axle (16R) and decoupled from the internal combustion engine (15), and a high-voltage battery pack (22) connected to the electric machine (20), wherein the method comprises: Accumulating the slip of the drive wheels (18) on the low coefficient of friction surface via a controller (14) using a pair of slip integrators, each having an integrator value for a corresponding first and second drive axles (16F, 16R), wherein the amount of slip changes in response to a reported axle torque and an activation status signal of the traction control system (19); Adding the integrator value for the first drive axle (16F) to the integrator value for the second drive axle (16R) to derive an integrator sum; and in response to the integrator sum exceeding a calibrated integrator threshold, executing a control action with respect to the hybrid powertrain system (12) via the controller (14), including automatically executing a weather mode in which the energy consumption of the high-voltage battery pack (22) is reserved for traction control and propulsion of the vehicle (10); Calculating a slip gain value (K) S ) depending on the reported axle torque (T AXL ) and a calibrated slip threshold, where the slip gain value (K S ) is positive if the reported axle torque (T) AXL ) less than or equal to the calibrated slip threshold; and Increasing the integrator values ​​by an amount equal to the slip gain value (K) S ), if the activation status signal is a Boolean 1 or TRUE and the slip gain value (K S) is negative; wherein the vehicle includes a windscreen wiper motor (13), and wherein the method (100) further comprises adjusting the calibrated slip threshold in real time in response to a speed of the windscreen wiper motor (13).

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