Atomizer motor drive design
With the global warming and air pollution becoming more and more serious, a series of lung diseases have also erupted. For lung diseases, atomization therapy is one of the best treatment effects internationally recognized. The so-called atomization therapy is The nebulizer atomizes the medicine into the body and directly enters the target organs such as the respiratory tract and lungs. It is faster and takes less medicine than ordinary oral medicines. Therefore, this treatment method is widely used by major hospitals.
In order to have a better therapeutic effect, when using different liquid medicines to perform nebulization treatment for different users, it is best to use nebulizers with different nebulization strengths according to the characteristics of the liquid medicine and the breathing rate of the patient. However, The prior art atomizers cannot adjust the atomization intensity, or have only limited operating gears, and the shortcomings of the atomization intensity selection range are small.
The compressed atomizer based on STM32 single-chip microcomputer has been greatly optimized in terms of parameters such as atomization intensity and speed. We can adjust it in a large range in real time through button settings.
In addition, the use of the electronic control unit allows this compressed atomizer to increase display, alarm and other auxiliary functions. Enable users to realize the use of compressed atomizer more quickly and effectively.
1. The overall block diagram design of the atomizer
In order to improve the reliability, stability and maintainability of the system, the design adopts the modular idea to design the hardware circuit. The single-chip microcomputer module is the core part of the design of the atomizer. It is mainly composed of the minimum system of the STM32 single-chip microcomputer and other hardware circuits to form an electronic control unit. The main functions of this module are: (1) Generate PWM modulation waveforms and send them as control signals to Motor drive module. (2) Process the signal from the button module, etc., and send the corresponding display information to the display module.
Second, the motor drive module of the atomizer
The main function of the motor drive module is to isolate the PWM modulation signal generated by the STM32 microcontroller and amplify its power. It can drive the compression motor stably and ensure the normal operation of the compression motor. The functions of the motor drive module are as follows:
(1) The output power reaches about 30W, which can drive high-power compression motors. (2) The drive circuit has high efficiency, can save power, and can also reduce the heat dissipation of the drive circuit. (3) The drive circuit has a good signal isolation effect on its input. (4) No matter what kind of control signal and what kind of passive load is added to the motor drive circuit, it is safe.
This module uses the BTN7971B chip to build an H bridge to drive the motor. The circuit is relatively complicated, but the H bridge drive capability of the two BTN7971B chips is strong, the current output is about 68A, and it has stable speed regulation, small on-resistance, and low performance loss. Etc. The 74HC244 eight-way positive-phase buffer/line driver is used to isolate and control the circuit to protect the main control chip. Its working truth table is shown in Table 1. The circuit diagram is shown in Figure 2.
Third, the software design of the atomizer motor drive system
The PWM wave generated by the STM32 single-chip microcomputer is the core of controlling the operation of the compression motor; using the button module to realize the modulation of the PWM wave pulse width can change the speed of the compression motor, thereby changing the degree of atomization; the button module also has functions such as selecting and setting user information .
After testing, this motor drive circuit can output about 30W of power, which can fully achieve the purpose of stably driving a high-power motor; therefore, the principle of this design can be used to produce a compression atomizer that is more in line with market needs. In addition, the STM32 microcontroller can support a wide range of 32-bit applications and has powerful functions; making this compressed atomizer have good plasticity and developability in future production and life, and we can adjust the atomization according to the different needs of users. Corresponding upgrades; in recent years, atomizers have become more and more popular. I hope this article can help the development of atomizers in the future.