Design of permanent magnet brushless DC motor controller
With the improvement of people's living standards, product quality, accuracy, performance, automation, function, power consumption, and price issues have become the main factors in selecting household appliances. The permanent magnet brushless DC motor not only has the advantages of simple structure, reliable operation, convenient maintenance, etc., but also has good speed regulation characteristics like DC servo motor without mechanical commutator. It has been widely used in various adjustments. Speed drive occasions. The emergence of MOTOROLA's second-generation motor control chip has brought great convenience to the design of permanent magnet brushless DC motor speed control device. These chips have strong control functions, perfect protection functions and stable working performance. The system consists of simple peripheral circuits and strong anti-interference ability. It is especially suitable for occasions where the working environment is harsh and the controller volume and price performance ratio are high.
2 controller structure and principle
2.1 controller structure
MC33035 is the second generation of brushless DC motor control ASIC developed by MOTORLORA. It adds one MC3309 electronic speed detector to convert the rotor position signal of the brushless DC motor to F/V to form the speed feedback signal. Closed loop adjustment system. Externally connected with six power switching devices to form a three-phase inverter, the three-phase permanent magnet brushless DC motor can be driven, and the controller circuit is constructed, as shown in Figure 1. In the figure, S1 controls the motor steering, and the S2 control system starts and stops, S3 Select system open loop or closed loop operation, S4 control system brake, S5 select turn
The sub-position detection signal is 60° or 120°, and the S6 controls the reset of the system. Potentiometer RP1 is used to set the required motor speed, and the light-emitting two-plate L1 is used as a fault.
Indication, when an abnormal position detection signal, main circuit overcurrent, one of three undervoltages (chip voltage lower than 9.1V, drive circuit voltage lower than 9.1V, reference voltage lower than 4.5V), internal overheating of the chip, When the start and stop ends are low, the L1 illuminates the alarm and automatically blocks the system. After the fault is removed, the system can be restored to normal operation.
2.2 Control principle
3 chip function
3.1MC33035 structural composition and function
Its main components include:
(1) a rotor position sensor decoding circuit;
(2) Internal reference power supply with temperature compensation;
(3) A sawtooth oscillator with a settable frequency;
(4) error amplifier;
(5) a pulse width modulation (PWM) comparator;
(6) an output drive circuit;
(7) Undervoltage blocking protects the chip from overheat protection and other fault outputs;
(8) Current limiting circuit.
Typical control functions of the integrated circuit include PWM open loop speed control, enable control (start or stop), forward and reverse control and dynamic brake control, plus some external components to achieve soft start.
3.1.1 Rotor position sensor decoding circuit
3.1.2 Error Amplifier
3.1.3 Pulse Width Modulator
3.1.4 Current Limit
3.2MC33039 electronic speedometer
4 experiments and conclusions
In order to better verify the feasibility and safety of the previous theory, experiments were carried out according to the design.
4.1 Preparation
4.2 Experimental conclusions
5 Conclusion
Although some phenomena that did not conform to the theory appeared in the experiment, in general, the experimental results basically reached the expected results, which proved the practical feasibility of using the transmission device for the small brushless DC motor writer.
