Control system and method for externally controlled variable-displacement compressor

Abstract

The invention provides a control system and method for an externally controlled variable-displacement compressor. A first PID control module is disposed in an evaporator temperature control circuit to calculate a temperature difference between an evaporator target temperature value and an evaporator actual temperature value to obtain target current; using a current difference between the target current and the actual current of a solenoid valve as the input of a solenoid valve current control circuit, a second PID control module calculates the input to obtain a PWM current signal with a corresponding duty cycle. Thus, the PWM current signal is used to control the displacement of the compressor so that the actual solenoid valve current gets close to the target solenoid valve current. Therefore, the actual evaporator temperature gets close to the target evaporator temperature so as to achieve synchronous precision control of the evaporator temperature and the solenoid valve current. By looking for different PID parameters, the evaporator temperature can be accurately controlled to get close to the evaporator target temperature under different ambient temperatures and different evaporator target temperatures, and a wider application range and higher efficiency and intelligence are achieved.

Description

technical field [0001] The invention relates to the technical field of variable displacement compressor control, in particular to a control system and method for an externally controlled variable displacement compressor. Background technique [0002] With the rapid development of the automobile industry, people's requirements for the performance and comfort of automobile air conditioners are constantly increasing. On the one hand, in the case of large temperature fluctuations in the car, the irreversible loss caused by the frequent start and stop of the system will increase the energy consumption of the system; on the other hand, the periodic clutching of the compressor will also cause serious interference to the work of the car engine. Therefore, in order to meet the load requirements of automobile air conditioners, variable displacement compressors emerged as the times require. [0003] The externally controlled variable displacement compressor has the characteristics of ...

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Problems solved by technology

[0004] However, the traditional algorithm only considers the control of the evaporator temperature by the variable displacement compressor. If the current protection is not considered, the solenoid valve will be damaged if the current of the solenoid valve is too large or too small, and the life of the solenoid valve will be shortened. In addition, the air conditioning and refrigeration system is a complex nonlinear system. The traditional algorithm only considers the setting of control parameters under a single working condition, resulting in poor control effect under other working conditions.

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