Power shunt hybrid power system mode switching control method based on state estimation

Abstract

The invention relates to a power shunt hybrid power system mode switching control method based on state estimation. For switching between a pure electric mode and a hybrid power mode of a power shunthybrid power system, the method comprises the following steps: S1, calculating a motor driving torque meeting a dynamic property requirement of a whole vehicle on an energy management layer based on atorque required by a power output end; S2, designing an unknown input observer on a coordination control layer to estimate a torque of an input shaft and a power output end of a gearbox on line; S3,based on the estimated torque value of the input shaft of the gearbox, designing a model prediction control strategy to realize stable start and stop of the engine and solve a start and stop torque ofthe motor; S4, designing a torque impact suppression strategy based on the torque estimation value of the power output end, and solving a motor compensation torque; and S5, superposing a motor driving torque, the start-stop torque and the compensation torque to obtain a target torque decision value of the motor. Compared with the prior art, the method has advantages that driving smoothness of thewhole vehicle in a mode switching process of the power shunt hybrid power system is improved, and the starting and stopping performance of the engine is considered.

Description

technical field [0001] The invention relates to a mode switching control method of a power split hybrid power system, in particular to a state estimation-based pure electric and hybrid power mode switching control method. Background technique [0002] The power split hybrid system is the mainstream technical solution for deep and plug-in hybrid electric vehicles. It uses the power split device of the planetary row and two motors to realize the decoupling of the engine working state from the wheel speed and the required torque. Reasonable switching between modes ensures that the engine and motor always work in the high-efficiency range, thereby maximizing the energy economy and emission of the vehicle. However, when the system switches between pure electric mode and hybrid mode, it is accompanied by a rapid start and stop of the engine. During this process, due to the influence of the reverse drag torque of the engine and the differences in the characteristics of different p...

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Problems solved by technology

During this process, due to the influence of the reverse drag torque of the engine and the differences in the characteristics of different power components, the torque at the power output end of the gearbox may fluctuate greatly, which will lead to prominent problems in the vehicle's power and driving comfort.

[0003] In the prior art, there are few studies on the mode switching process control of the power-split hybrid power system. In practical applications, traditional rule-based and empirical logic gate-limited switching control strategies are mostly used. greater limitations

Prior art CN107351837A discloses a mode switching method of a power split hybrid power system. Aiming at the pure electric to hybrid mode switching process of a power split hybrid power system, a control method combining offline optimal control and online model predictive control rolling optimization is proposed. However, the model predictive control of this method does not consider the limits of the engine speed, motor torque and its rate of change in the actual system, and does not combine and utilize the estimated information of the gearbox input shaft and power output torque.

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