TI leads efficient motor control chip technology

With the continuous development and updating of air conditioning technology, electronic control technology has fully entered the era of frequency conversion, especially in the ultra-low frequency Hertz era. The lower the frequency, the more precise the air conditioning control, the more comfortable the feeling, and the more energy-efficient it can be.

Over the past twelve years, TI has worked closely with Chinese air conditioning companies on all key technological innovation nodes from AC frequency conversion to DC frequency conversion and then to low-frequency frequency conversion control, overcoming various difficulties and gaining widespread recognition and respect from the industry.

Given the mainstream status of frequency conversion technology and the importance of corresponding motor control technology, the biennial industry technology event 2012 International Refrigeration Technology Exchange Conference, which just came to an end in Zhuhai, has set up a special seminar on electronic control technology for the first time. TI company (the only semiconductor chip supplier) has been invited as the supporting unit and academic speaker unit of the conference to discuss the latest topics and achievements of efficient motor control technology with experts, scholars, and R&D personnel in the refrigeration and air conditioning industry.

As one of the world's largest semiconductor companies, Texas Instruments' innovative analog, embedded processing, and wireless technologies have penetrated into every aspect of people's daily lives. Based on the concept of creating a smarter, safer, more environmentally friendly, healthier, and more exciting world, TI company began to enter the field of energy-saving air conditioning motor control in China in 2000, which can be said to have accompanied and witnessed the rapid progress of technological innovation in China's variable frequency control field. We are willing to work with Chinese air conditioning and refrigeration industry players to continue contributing to energy conservation and emission reduction, and to create a better ecological environment! Zhang Haikun, General Manager of TI South China, stated in his opening speech at the Electronic Control Symposium.

Over the past twelve years, TI has worked closely with Chinese air conditioning companies on all key technological innovation nodes from AC frequency conversion to DC frequency conversion and then to low-frequency frequency conversion control, overcoming various difficulties and gaining widespread recognition and respect from the industry. As one of the important participants in this process, Dr. Tan Hui, the manager of the MCU application department of TI Semiconductor Business Unit, also received a grand introduction from the chairman of this year's electronic control seminar.

Dr. Tan has over ten years of experience in motor control research and technical support, and maintains close connections with numerous academic and applied research institutions in motor control at home and abroad. Therefore, the mainstream and emerging high-efficiency motor control technologies discussed in his technical speech, as well as some cutting-edge research projects involving TI that are still in the research stage, have attracted strong attention from the attendees.

The key element of truly efficient motor

China holds a very important position in the field of motor control, with 7 billion out of the world's annual production of 8 billion motors being made in China. For high-efficiency motors, permanent magnet synchronous motors are currently the mainstream. However, due to the close relationship between permanent magnet motors and rare earth materials with significant price fluctuations, it has brought some impacts and fluctuations to the industry, making us more cautious about the future development of this high-efficiency motor. This is one of the reasons why I will also mention another emerging high-efficiency motor and its control technology today. Dr. Tan pointed out at the meeting.

Dr. Tan first analyzed the important factors that affect the characteristics of high-efficiency motors based on the most widely used induction motor. Induction motors can achieve an efficiency of nearly 95% in high-power situations, such as motors over tens of kilowatts. However, low-power motors have very low efficiency points, such as single-phase fans, which are only about 30-40% The efficiency of a motor is not only related to its power (which is related to the proportion of its excitation current), but also to the environment in which the motor operates. If a motor design itself is optimized but always operates in a very unfavorable situation, such as below 20% of full load, the efficiency will be very low. In addition, the power factor of the motor itself is another crucial indicator that affects efficiency.

Induction motors exhibit different performance depending on the power level of the motor, but if they are mostly in the load range of 40-80%, the system's utilization rate of the motor itself is acceptable. So when considering the control system, it is crucial to determine the range in which the system should operate, including the power factor, which has a significant impact on efficiency.

Dr. Tan summarized some advantages of the widespread application of induction motors: 1. Low cost, which can be directly connected to the power grid for operation; 2. Even without a controller, it is possible (of course, the cost is mainly in terms of energy efficiency); Furthermore, its torque coefficient is low, and it can generate a very stable magnetic field space under single-phase current conditions. In addition, it does not have permanent magnets, does not lose magnetism, and is not afraid of vibration or rust, so it is relatively reliable. In terms of control, it is very easy to enter the high-speed weak magnetic control zone, and there are multiple motors available in a large power range.

But there are also drawbacks: the efficiency is very poor under light load conditions, and the size is much larger than that of permanent magnet motors under the same process. From a control perspective, while achieving high efficiency in motors, it is now desirable to use vector transformation and vector control. This is because the rotor side current is large and the temperature changes greatly, resulting in significant changes in rotor side resistance. This poses difficulties for parameter based control strategies such as induction motor vector control and is a major technical challenge.