The laboratory centrifuge is an instrument for separating samples. It is widely used in the fields of dry biomedicine, petrochemical, agriculture, food hygiene, etc. It uses the difference in precipitation speed of different substances in the centrifugal force field to realize the analysis and separation of samples. Since the advent of the centrifuge, the progress of low speed, adjustment and overspeed has been mainly reflected in the centrifugal equipment and centrifugal technology, and the two complement each other. From the perspective of rotational speed, the desktop centrifuge is basically in the category of low-speed, high-speed centrifuges. Therefore, it has the technical characteristics of low-speed and high-speed centrifuges. Its structure is mainly composed of motor drive system, refrigeration system, mechanical system, rotor and system control. composition. The development of universal benchtop centrifuges has blurred the boundaries of low-speed, high-speed centrifuges. Many rotors provide researchers with a wide range of applications and become the preferred model for research laboratories. AC frequency conversion speed regulation will gradually replace DC speed regulation. The speed regulation system is the core part of the centrifuge. It consists of three major elements: control, power drive and motor. It mainly controls the speed of the motor. In the development process of centrifuges, DC speed regulation is indispensable. Its main features are good braking, wide speed range, simple structure, low cost, mature theory and practice, etc., so it was before the 1980s. Widely used in centrifuges, it is still being applied and continuously improved, such as improving the wear resistance of DC motor copper heads and carbon brushes to extend the life of the motor and the replacement cycle of the carbon brushes. Controllable DC speed regulation is a classic DC speed regulation scheme. It has a simple structure and mature technology, and basically meets the requirements of centrifugal speed regulation. Therefore, it is widely used in centrifuges at home and abroad. The main disadvantages are that the rectification waveform is poor, the current ripple is large, and the current interruption is easy when the load is light. To maintain the continuity of the DC motor current, a heavy and smooth inductor is added, which increases the volume and weight of the instrument. After the 1980s, with the development of fully controlled power devices, such as power transistors and FETs, switching power conversion technology has gradually been applied in centrifuge DC speed control systems. This technology is mainly through high frequency DC chopping. , adjust the pulse width ratio, change the auxiliary voltage, and supply power to the DC motor. Because the switching frequency is very high, generally less than 50KHZ can only obtain smooth DC current by the motor's own inductance filtering, which overcomes the shortcomings of DC speed regulation, so the speed is smoother and the speed regulation range is wider. Open-loop speed regulation is the simplest speed control scheme. Even a dozen discrete components or an integrated block can form a system. Therefore, some low-cost centrifuges in China still adopt this scheme. The main disadvantage is that it needs Manual speed regulation, can not control the current of the motor, the speed accuracy and technical added value are relatively low. In view of the limitations of open-loop speed regulation, most centrifuges at home and abroad generally adopt a double closed-loop speed regulation scheme with both current feedback and speed feedback. The main advantages are automatic speed regulation, fast speed increase, small speed overshoot, and accuracy. High and current limiting function to avoid motor overcurrent damage. Although the DC speed regulation has a long history and mature technology, the DC motor mechanical commutator commutation is its fatal weakness, which limits the speed of the motor, the commutator causes interference, and needs to replace the carbon brush, which makes the early overspeed or high speed centrifuge. Indirect speed-up solutions such as gear shifting or other methods have to be used, increasing cost and volume, reducing life and reliability. At the end of the 1970s, foreign ultracentrifuges took the lead in adopting variable frequency speed control technology, mainly by changing the power supply frequency of the induction motor to adjust the speed. Since the induction motor does not need mechanical commutator, it not only eliminates the trouble of replacing the carbon brush, but also increases the motor speed. Even the ultracentrifuge of hundreds of thousands of revolutions can be directly driven, which greatly simplifies the structure of the centrifuge. The key technology of frequency conversion speed regulation: First, the development and application of fully controlled power devices, simplifying the technical key of speed regulation: First, the development and application of fully controlled power devices, simplifying the main circuit of the inverter; second, SPWM technology Improve the performance index of the inverter; Third, the development of control technology, such as vector control technology, so that the control performance of the induction motor meets or exceeds the level of the DC motor; Fourth, the large-scale integrated circuit and microprocessor for variable frequency speed regulation The frequency conversion circuit is greatly simplified, and the current frequency conversion speed regulation is comparable to the DC speed regulation. After the 1990s, almost all foreign major centrifuge manufacturers used variable frequency speed regulation technology. Regardless of overspeed, high speed, or low speed centrifuge, China also listed frequency conversion speed centrifuge as a research plan. Some manufacturers have introduced frequency conversion. Speed ​​control centrifuge. According to the different AC motors, the frequency conversion speed regulation is also different. At present, there are three main types of motors used in the frequency conversion speed control centrifuge: asynchronous induction motor, brushless DC motor and variable reluctance motor. 1988 2, multi-function, automation and computer control With the development of centrifuge manufacturing and application technology, centrifuges not only make progress in speed control technology, but also make great progress in multi-function and automation, such as variable speed braking, program shifting, direct input centrifugal force, operating procedures. The storage and recall, the automatic diagnosis of the instrument status, the requirement to display the parameters and status information of the centrifuge as much as possible, and the more perfect safety protection functions, etc., some functions are not only the icing on the cake, but also directly affect the centrifugal effect, such as variable rate Braking and program shifting can improve zone centrifugation and shorten centrifuge time. The early centrifuge control system consisted of discrete components, the circuit was complex, the cost was high, and many functions were difficult to achieve. After adopting the microcomputer technology, the function of the hardware can be replaced by software or the functions that are difficult to implement by the hardware, such as the centrifuge program control and the motor control, which not only greatly simplify the structure of the hardware, but also become multifunctional and automated. The core of the general centrifuge computer control system is a single-chip microcomputer. The hardware system includes: operation interface, motor control interface, temperature control interface, security protection monitoring interface, system monitoring and so on. The operation interface manages the keyboard and display. For the convenience of user operation and monitoring of operating parameters, the operation interface should follow the principle of simple and concise, logical and clear parameters. Improper use of centrifuges, such as overspeed, overload, unbalance, etc., may damage the instrument, or even the head, threatening personal safety, so manufacturers pay special attention to safety design, international and national standards are also set, centrifuges And the industry standard for centrifuge tubes. The mechanical safety design mainly includes the following contents: 1 door lock protection system, using mechanical and electronic double-layer door locks, the centrifuge can be started after the door lock is closed, and the cover can be opened after the motor stops moving. 2The centrifuge chamber and cover are made of solid armor steel, which is very important to prevent the imbalance of the rotor head. The unbalance of the rotor will cause the motor shaft to swing and affect the life of the centrifuge. In severe cases, It will break the motor shaft and even the head. Unbalance is typically detected by detecting the swing of the motor shaft. 4 Improve the anti-unbalance ability of the centrifuge itself, not only can improve the robustness of the centrifuge, but also need not be strictly balanced or even visually balanced due to the operation of the rotary head, thus facilitating the user's operation. Generally, a small centrifuge places the entire motor on a seismic elastic bracket, such as a rubber mat. The high-speed centrifuge also often uses a sturdy shaft to resist earthquakes. The 5 rotor recognition system can automatically identify the rotor and limit the maximum speed of the rotor, effectively preventing the user from misoperation. The basic principle of rotor recognition is to set a unique code for each rotor, or to inlay a certain number of small magnets at the bottom of each rotor, using sensing, or using photoelectric refraction ring sensing, more complex with ultrasound and The wireless RF rotor recognizes the head, the rotor can be identified without running, and even the cover can be detected. Environmental protection is mainly manifested in two aspects. Noise reduction, generally speaking, the voice is 60 points p, the public air driving sound is 70 to 80 decibels, medical research shows that more than 70 decibels of noise can interfere with the conversation, causing upset, affecting work, and even causing accidents, according to China Product quality inspection agency measurement certification technical assessment specification (fiG102-90), the noise of the test laboratory shall not exceed 70dBo. Generally, the noise reduction measures of the centrifuge are: the outer casing and the rotating head cavity plus the sound absorbing coating; the solid and stable earthquake resistance is adopted. The base tonnage machine is isolated from the mechanical frame by an elastic shock absorber; the use of a commutatorless motor is required. Generally, after the shock absorption treatment, the noise of the centrifuge can be limited to 60 decibels. Strict requirements, products that have achieved standard certification can gain more trust from users. More mini centrifuge information login: Wireless Doorbell,China Smart Video Doorbell, Wireless Doorbell Villa,Wireless Video Doorbell Office,Wireless Video Doorbell Batteries Zhuhai Mingke Electronics Technology Co., Ltd , https://www.mingke-tech.com