Research On High Precision Embedded Digital Power Regulator Applied To High Temperature Vacuum Kettle

Aiming at the request of the temperature controlling system of the high temperature vacuum kettle which produces sapphire crystal, an embedded digital power regulator with high accuracy is designed in the dissertation.The silicon controlled regulator (SCR) which is easy to control is applied in this dissertation to adjust the conduction angle of three-phase alternating current (AC). The controlling principle, work parameters and trigger request of SCR are introduced in the dissertation. The precision of zero-crossing detection circuit determines the precision of the conduction angle controlled by SCR. A detection circuit with high accuracy is designed in the dissertation, which has the characteristics of outputting zero-crossing pulse, and acquiring the point of zero-crossing by the rise edge and fall edge of the pulse. After acquiring the feedback signals of voltage and current by the high precision Hore senor of voltage and current, the AC/DC convertor of True Root Mean Square is used to transform alternating current to direct current. The analog-to-digital converter AD7784 which has high speed and high accuracy is applied in analog-to-digital conversion. In order to improve the precision of analog-to-digital conversion, over-sampling technique is applied. In the over-sampling circuit designed in the dissertation, triangle wave signal can be added to the feedback signal. The microprocessor MSP430F149 which has low power is adopted as the controlling unit. It is used to receive and handle zero-crossing detection signal, output PWM pulse, control analog-to-digital converter and so on.The software design of the system includes the software design of the host machine and the software design of the slave machine. In the software design of the host machine, the functions of timing and interrupting of counter-A is used to realize the detection of zero-crossing pulse and receive the data from the slave machine; the controlling arithmetic of increasing PID is used to calculate the conduction angle of SCR; the counter-B is used to output PWM pulse. In the software design of the slave machine, the PWM pulse which is required to generate triangle wave signal is output. The software of the slave machine also controls the analog-to-digital convertor to convert analog data to digital data and process the converted data.Firstly, the development, characteristics, mission management and its transplantation to the microprocessor MSP430F149 of the embedded real time multi-mission operation system are introduced. Then, the hardware design and software design of the system are discussed. At last, some methods and measures of anti- interfering design are put forward in the dissertation.