In the abstract automatic control system, the proportion electro-magnet which controls by the microprocessor takes actuator’s application to be getting more and more widespread. This design is one interface circuit which controls by the C8051F005 monolithic integrated circuit, uses the PWM technology to carry on the control to the proportion electro-magnet; Simple practical, can satisfy in the automatic control system actuator’s control precision high, to respond the quick request, has certain use value.
The key word C805lF005 proportion electro-magnet controls PWM
Introduction
The proportion electro-magnet takes the functional element, is one of integration of machinery key products, widely applies in each kind of automation control system; The proportion electro-magnet’s thrust force is big, the structure is simple, maintains conveniently, the cost is inexpensive, is the application very widespread electricity pneumatic machinery switch; The proportion electro-magnet’s characteristic and the work reliability, has the very important influence regarding the entire control system, decides one of control system quality key components. The proportion electro-magnet takes the electricity machinery transition element, its function is the electric current signal which loses to the proportional control amplifier, transforms the displacement or the strength signal output. The proportion electro-magnet is suitable in the DC voltage is in 24 V proportional control amplifier’s control wiring, takes continuously, in proportion the control system functional element’s movement, the speed and the direction power part.
The proportion electro-magnet’s with passes over its coil in its rated stroke scope thrust force the electric current to be proportional, may take the linear power part in other need action automatic control installment. If autothrottle control and so on. When the electro-magnet and the monolithic integrated circuit constitute a automatic control system together, because the electro-magnet working voltage is high, the operating current is big, therefore between the monolithic integrated circuit and the proportion electro-magnet interface circuit’s design is a key.
Along with the microelectronic technology and computer technology’s development, the proportion electro-magnet’s demand grows day by day, has the application in each control domain. Following introduction proportion electro-magnet control technology.
1 PWM actuation basic principle and characteristic
PWM (Pulse Width Modulation, pulse width modulation) the technology is uses the semiconductor switch component’s breakover and the shutdown, turns the voltage pulse row the DC voltage, and achieves the live pressure, the frequency conversion goal one kind of control technology through the control voltage pulse width and a pulse row cycle. Is also with the pulse width different a series and so on peak-to-peak value square pulses to approach the electric current which or the voltage signal an institute needs.
The PWM driving circuit, is widely applies in the high accuracy control system’s actuation form. This kind of electric circuit can realize the wide scope speed and the position control, has the incomparable merit compared with the convention drive type. The PWM driving circuit line is simple, the rapidity is good, the linearity is good, the efficiency high merit, causes it widely to apply in the survey, the correspondence, the power control and in transformation many domains. This design uses the PWM driving circuit to need the high efficiency controllable component to be few, the governor deflection width, the rapidity are good, the efficiency is high, the power loss low characteristic, with C805lF005 the monolithic integrated circuit direct output’s PWM signal after the driving circuit, then the coordination appropriate control algorithm (the PID algorithm or fuzzy control algorithm and so on) controls the proportion electro-magnet, may realize to Taiwan’s accuracy control, has the very good reference value regarding the electrically controlled clutch control system’s research.
2 proportion electro-magnets and monolithic integrated circuit interface circuit
2.1 monolithic integrated circuit outlines
This control system uses the monolithic integrated circuit is US with the C3051F005 monolithic integrated circuit which Silabs Corporation promotes. It is the composite signal system-level MCU chip which integrates completely, some 1 true 12 multichannel ADC, 1 increase the amplifier, 2 12 DAC, 2 voltage comparator, 1 voltage datum, 1 to have the 32KBFlash memory and with 8051 compatible micro controller essences programmable, but also has the hardware to realize (is not in user software with position operation simulation) I2C/SMBus, UART, the SPI serial interface and 1 has 5 capture/comparison module programmable counter/timer array (PCA), as well as 4 general 16 timers and 4 byte wide general digital I/O port. C8051F005 has 2304 byte RAM, carries out the speed to be possible to reach 25MIPS; Has the internal VDD monitoring device, WDT and the clock oscillator, is can truly on the independent working piece the system, can manage the simulation and the digital peripheral device effectively. The Flash memory also has in the system programs ability, may use in the non-volatility data storage, and allows the scene to renew 8051 firmwares. MCU may close any or the complete peripheral device, reduces the power loss.
The C8051F005 monolithic integrated circuit may (145 ~ 85℃) in use 2.7~3.6 V voltage work in the industry temperature range. Port I/O, RST and the JTAG pin allows 5V the input signal voltage.
2.2 PWM signal output and proportion electro-magnet driving circuit
C8051F005 MCU has internal programmable counter/timer array PCA. PCA including 1 special-purpose 16 counter/timer time reference and 5 programmable capture/comparison module. Time reference’s clock may be under one of 4 clock sources: The system clock /12, system clock /4, timer 0 overflows or the external clock input (ECI). Each capture/comparison module has own I/O line (the CEXn line), when permits it works, the CEXn line through the function selection switch company arrives at port’s some pin.
Each capture/comparison module has 4 workings: Border triggering catches raises, the software timer, the high speed output, the pulse width to modulate (PWM). PCA capture/comparison module’s I/O and the external clock input may arrive at MCU through the digital overlapping switch company the port I/O pin.
Outputs 8 PWM signals by PCA (dutyfactor invariably) the procedure to be as follows:
According to the system design need, through revises PCA0CPH0 to be possible to obtain the different dutyfactor PWM signal.
This control system uses C8051F005 monolithic integrated circuit’s PCA to realize 8 resolution PWM outputs by the software. The PWM signal arrives at MCU through the CEXn line from the function selection switch company the port I/O pin output, the PWM output signal may actuate the proportion electro-magnet through the driving circuit. In module capture/comparison register PCAOCPLn and PCA0CPHn deposits the PWM output signal dutyfactor high level time value. If needs to change the dutyfactor, may change PCA0CPHn in the movement the value, the proportion electro-magnet throwout lever displacement and the PCA0CPHn value becomes the proportion.
In the driving circuit needs the PWM output voltage signal conversion for the proportion electro-magnet controlling current signal, moreover must guarantee the good proportion characteristic relations. Using the field effect tube’s jump characteristic, on the scene the effect tube when leaks between the source voltage VDS maintains is invariable, drain electrode electric current ID and between the grid source the voltage VDS relations are called “the jump characteristic”, its expression is:
This control circuit has used high efficiency field effect transistor IRL3803, its electric current output enough actuation proportion electro-magnet movement. IRL3803 drain electrode electric current ID and grid source voltage VGS has the very good linear relationship, mouth (programs PCA the electronics grid and C8051F005 monolithic integrated circuit’s PO.0 through software choice PWM signal output pin), is connected the IRL3803 drain electrode and the proportion electro-magnet. In this electric circuit, the proportion electro-magnet is GP80, its fixed suction is 120N, the traveling schedule is 8mm, the rated voltage is 24 V.
When carries on the control, inputs through the change to the proportion electro-magnet switch electrical signal “the dutyfactor” realizes the controlling current size. The dutyfactor is bigger, is bigger through magnet winding’s controlling current, the control output’s displacement is also bigger.
Proportion electro-magnet driving circuit as shown in Figure 1. In driving circuit.
Rl is a limiting resistor, causes the IRL3803 tube breakover; Dl guides the diode, provides the correct voltage polarity to the IRL3803 tube; Diode D2 plays the protective function, avoids presses when damaging the proportion electro-magnet. The proportion electro-magnet supplies power directly by 24 V voltages.
Conclusion
The C805lF005 monolithic integrated circuit’s integration rate is high, the peripheral circuit are few, its high speed executive order’s characteristic can the accuracy control proportion electro-magnet; The C8051F005 essence and the ordinary 5l series are compatible, and the instruction simple easy to study, may reduce the system development cycle. The proportion electro-magnet transforms the component as the electricity machinery, already obtained the widespread application. Can achieve the precision based on the C8051F005 monolithic integrated circuit’s proportion electro-magnet control system to be high, the stable good request, the hardware circuit is simple, operation reliable. In the application system, according to needs directly by monolithic integrated circuit’s I/O mouth output fixed dutyfactor or the invariable dutyfactor PWM signal, matches by certain control algorithm, the software programming clear and easy to realize, has the very good promoted value.
