*Article* **Research on Fault Diagnosis of HMCVT Shift Hydraulic System Based on Optimized BPNN and CNN**

**Jiabo Wang 1,2, Zhixiong Lu 1, Guangming Wang 3, Ghulam Hussain 4, Shanhu Zhao 5, Haijun Zhang <sup>1</sup> and Maohua Xiao 1,\***


**Abstract:** There are some problems in the shifting process of hydraulic CVT, such as irregularity, low stability and high failure rate. In this paper, the BP neural network and convolutional neural network are used for fault diagnosis of the HMCVT hydraulic system. Firstly, through experiments, 120 groups of pressure and flow data under normal and four typical fault modes were obtained and preprocessed; they were divided into 80 groups of training samples and 40 groups of test samples via random extraction, using the BP neural network model and convolutional neural network model for fault classification. The results show that compared with BP, PSO-BP and other models, the fault diagnosis rate of the BAS-BP neural network model can reach 92.5%, and the average diagnosis accuracy rate of the convolutional neural network can reach 97.5%, which can be effectively applied to the fault diagnosis of the HMCVT hydraulic system and provide some reference for the shifting reliability of hydraulic CVT.

**Keywords:** HMCVT; fault diagnosis; BP algorithm; CNN; attribute reduction
