| 黄永军，李顶根，陈国华.基于自适应延时PI控制器的汽油机λ双环控制策略的研究[J].内燃机工程,2017,38(5):76-83. |
| Study on λ Dual Loop Control Strategy for Gasoline Engines Based on PI Controller with Adaptive Time Delay |
| DOI： |
| Key Words:IC engine dual loop control λ control oxygen sensor unilateral time delay PI control |
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| 摘要点击次数: 3201 |
| 全文下载次数: 2009 |
| Abstract:For an engine equipped with dual switch- type oxygen sensors upstream and downstream of the three way catalyst（TWC）, an innovative adaptive dual-loop λ control strategy was proposed. The front oxygen sensor upstream of the TWC was used to perform PI feedback control of the closed-loop control factor and the rear sensor downstream of the TWC was used to monitor and correct the λ in real- time. If the front oxygen sensor voltage output characteristic shifts remarkably due to aging or oil-poisoned, the traditional closed-loop PI method can not prevent the λ from deviating from 1, resulting in a deteriorated efficiency of the TWC. Therefore, in the proposed control strategy, every time the front oxygen sensor voltage steps, a freezing mode and a freezing period are calculated depending on the offset of the rear oxygen sensor voltage from its reference value and applied to freeze PI adjustment and delay the closed-loop control factor to invert jump for a specific period. The closed-loop control factor is maintained at the maximum/minimum state during the freezing period. In this way, an asymmetric controller with unilateral time delay is formed to compensate the λ offset so that the λ can be controlled precisely in the ideal operation range to achieve an optimum conversion efficiency of the TWC. The advanced software ASCET is used to graphically model the controller and automatically generate C codes. After being integrated with the baseline driver code, C codes are downloaded to MPC5634 hardware platform and installed on an engine bench to experimentally demonstrate the effectiveness of the proposed control strategy. The results show that the λ can still be precisely controlled within the ideal range of 0.99 to 1.01 even if the front oxygen sensor malfunctions. |
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