Design and Analysis of Digital Speed ​​Regulation System for Diesel Generator Sets (1)

Design and Analysis of Digital Survey System for Diesel Generator Sets (1) Cao Shihong, Wang Zhengmao, Yang Yitao, Design and Analysis of Digital Speed ​​Control System for Diesel Generator Sets (1) Cao Shihong\Wang Zhengmao\Yang Yitao\ Cheng Zhijun2 (1. Xi'an Jiaotong University, Xi'an 710040, China) 2General Construction Institute, Xi'an 710032, China) 1 Basic Principle of Speed ​​Regulation The diesel engine speed control system detects the change of the rotational speed through the rotational speed electromagnetic sensor installed on the flywheel shell, and is controlled by the electronic governor. Drive the throttle lever to adjust the oil supply amount, so as to achieve the purpose of automatic speed adjustment. The speed control system is mainly composed of the speed detecting unit, the electronic governor unit and the actuator. The detecting part is mainly composed of the rotational speed electromagnetic sensor and the flywheel ring gear. The electromagnetic sensor measures the rotational speed of the engine from the flywheel ring gear, and converts it into a pulse signal proportional to the rotational speed and inputs it to the electronic governor. The electronic governor compares the rotational speed signal with the given rotational speed signal, and performs Corresponding control operation, and then the actuator (actuator) is driven by the power output link. Change the amount of oil supply, automatically adjust the speed of the diesel engine, and the structure of the diesel engine speed control system. The speed sensor detects the change of the number of teeth of the engine flywheel and obtains an AC frequency signal proportional to the speed of the diesel engine.

The induced AC frequency signal is related to the diesel engine speed and the number of teeth. The test engine is a German Deutz F6L912 six-cylinder engine. The number of flywheel teeth is 130. If the engine speed is 1500r/min, the f is 3250Hz 1.2 actuator actuator. When the connecting rod is connected with the throttle of the diesel engine, when the power amplifier of the electronic governor is driven by sufficient current, the exciting coil flows through the current to generate electromagnetic force to the moving iron core, so as to overcome the spring force of the return spring and open the throttle. Change the amount of oil supply.

1.3 Electronic governor Electronic governor is a negative feedback adjustment system composed of the principle of “deviation” adjustment. It mainly consists of the measuring link (including the shaping and amplifying module) given link and control operation (due to the use of digital microprocessor, The algorithm can be diversified, such as PID8 operation fuzzy Fuzzy9 operation, etc.) Protection module display module, drive module, etc. At present, most of the electronic governors for diesel generator sets at home and abroad still use analog circuits to achieve [2,] the most typical two The company is the United States Woodward company and Germany Heinzmann company, the two companies use analog circuits to achieve PID computing. The specific implementation is different: Woodward's proportional link uses phase-locked loop technology , its input is the amount of frequency. Heinzmann uses frequency-frequency conversion technology to convert the frequency signal of the electromagnetic sensor into voltage, and then compare and amplify. For digital electronic governor, only Newcastle has commercial products at home and abroad, and its control is adopted. The normal PID operation, the parameter setting of each parameter must be adjusted with the corresponding equipment. The block diagram based on the 87C51FB speed control system is shown.

2 Mathematical model analysis of speed control system The diesel engine speed control system is essentially a speed control system, that is, speed closed-loop control. This paper introduces the digital model of each link in the closed-loop control, and takes PID correction as an example to use the frequency method to system stability. The analysis is carried out to study the influence of various parameters on the dynamic process quality of the system and the optimal parameter range, which provides a reliable basis for further improving the design and optimization algorithm.

2.1 Diesel Engine The diesel engine itself has nonlinear and open-loop instability, but it can be used to simulate the torque response of the diesel engine with a simple first-order model. The transfer function can be expressed as: the dimensionless amount of diesel torque ( s) is the dimensionless quantity of the diesel engine load, h(s) is the dimensionless quantity of the diesel engine speed, U is the diesel engine self-tuning coefficient, f is the diesel engine torque pulse delay time, Ta is the diesel engine speed rising time constant, q is Number of fires per forward

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