Abstract
In recent years, with the rapid development of power electronic technology,
microelectronics, new type control theory of motor and permanent magnetic
material of rare earth, permanent magnet synchronous motors are being rapidly
promoted and utilized. Permanent magnet synchronous motor has a small size, low
power loss, high efficiency, and with the increasing concerns of energy saving and
protection of environment in today’s life, research of it is of great necessity. AT89
series microcontrollers of ATMEL Corporation is one of the most widely used
8-bit microcontrollers. Its advantages of high performance, low price, low power
consumption, large storage capacity, simple instructions and easy to learn make it
widely used in industrial detection and control systems. In the management of
motors, parameters of electricity such as voltage, current, power, power factors are
usually necessary to judge and adjust their states aiming at removing hidden
dangers, saving energy and improve efficiency. This design is based on the
microcontroller of AT89S51, through the transformation of the transformer, hall
current sensor, A/D converter and analog switch to get the instantaneous value of
AC voltage and current. According to sampling theorem, if the sampling
frequency is up to two times of the signal, the sampled values which are discrete
can preciously reflect the analog signal. In this way, we can calculate the effective
value accurately. The existing phase difference between AC voltage and AC
current leads to the formation of the power factor. If the signals of voltage and
current go through the over zero comparator, there must be two square waves with
time difference output which we can utilize to access the two external interrupt
entrance of AT89S51. We can handle the interrupts in routines with the timers
inside the microcontroller which can easily calculate the power factor and the
power input the motors.
Key words
Permanent Magnet Synchronous Motors, ATMEL, Microcontroller,
Electricity parameters