A new member in the field of brushless motor is expected to appear, that is, a new type of switched reluctance motor. For a long time, permanent magnet motor has been widely used in many fields for its excellent energy efficiency ratio. However, the high cost of rare earth materials limits its use.

According to the latest news, the British have developed a brand-new "switched reluctance motor", which also does not rely on rare earth, and is more energy-saving than ordinary permanent magnet motors on the premise of the same torque density, and is expected to enter the practical field next year.

What is switched reluctance motor?

Switched reluctance drive (SRD) is the latest generation of stepless speed regulation system developed after variable frequency speed regulation system and brushless DC motor speed regulation system. It is an optical, mechanical and electrical integration high-tech integrating modern microelectronics technology, digital technology, power electronics technology, infrared photoelectric technology and modern electromagnetic theory, design and manufacturing technology. It has the advantages of both DC and AC speed regulation systems. Britain, the United States and other economically developed countries have started the research on switched reluctance motor speed regulation system earlier, and have achieved remarkable results. The product power level ranges from several kW to hundreds of kW, and is widely used in household appliances, aviation, aerospace, electronics, machinery, electric vehicles and other fields.

In fact, the research and trial production of switched reluctance motor speed regulation system in China started in the late 1980s and early 1990s, and has made achievements and progress in many aspects from basic theory to design and manufacturing technology, but the industrialization and application research work is relatively lagging behind.

Working principle: the working principle of switched reluctance adjustable speed motor follows the "principle of minimum reluctance". After power on, the magnetic circuit tends to change to the path of minimum reluctance. When the rotor salient pole and the stator salient pole are misaligned, the air gap is large and the magnetic resistance is large; Once the stator pole winding is energized, it will form a magnetic pull on the rotor bulge, making the air gap smaller - the magnetic resistance of the magnetic circuit smaller. At the same time, by switching the energized phase sequence of the stator pole winding with an electronic switch according to a certain logical relationship, a continuous rotating torque can be formed. The speed regulation function of switched reluctance motor is realized by the cooperation of rotor position detector, power converter and controller of switched reluctance motor. It is a high-tech optical, mechanical and electrical integration system.

Advantages: the advantages of small starting current and large starting torque are also obvious in the low-speed operation section, which is suitable for frequent starting occasions; Good low-speed characteristics: the SRD system maintains a constant torque at 100-1500r/min, especially below 500r/min, and the torque can be 1.2 times the rated torque. Large torque is maintained in the low-speed section, and the motor does not heat up after long-term low-speed operation. Because it belongs to brushless motor, its speed regulation ratio is greater than 20:1, the speed regulation is smooth, and brushless stepless.