As the core power component of manufacturing equipment, the power density of the spindle motor directly determines the compactness, dynamic response, and processing efficiency of the equipment. Power density refers to the power output per unit volume or weight, and improving this indicator requires achieving power within a limited space. The core logic revolves around "loss control" and "energy conversion efficiency optimization", involving multi-dimensional collaboration such as material innovation, structural design, and control technology.
Upgrading the iron core material is the foundation for improving power density. Traditional silicon steel sheets suffer from high hysteresis and eddy current losses, which limit the increase in magnetic field strength and frequency. By using ultra-thin oriented silicon steel with high silicon content, the hysteresis loss can be reduced by refining the grain size, while reducing the length of the eddy current path, allowing the iron core to maintain low loss characteristics under high-frequency conditions. More advanced amorphous alloy materials have lower coercivity due to disordered atomic arrangement, and their core loss is only 1/5 to 1/10 of traditional silicon steel, creating conditions for improving excitation density and speed.
Optimization of winding design is a key breakthrough point. Replacing traditional round wire winding with flat wire winding can increase the slot occupancy rate from around 40% to over 70%, significantly increase the cross-sectional area of the conductor and reduce the gap inside the slot, and improve the current carrying capacity under the same volume. At the same time, the card type winding process is used to flatten the end of the winding, shorten the length of the end to reduce copper loss, and improve the insulation performance with the vacuum impregnation process, so that the winding can withstand higher current density and temperature.
Innovation in magnetic circuit structure further unleashes spatial potential. The built-in permanent magnet synchronous spindle motor can achieve higher speeds by embedding permanent magnets inside the rotor core, avoiding the risk of permanent magnet detachment during high-speed rotation. By using Halbach array to arrange permanent magnets, a higher sinusoidal magnetic field can be formed in the air gap, reducing the additional losses caused by magnetic field harmonics and lowering the demand for permanent magnet usage, resulting in a smaller rotor volume under the same magnetic potential. In addition, optimizing the tooth slot structure of the stator and rotor can weaken the tooth slot torque and improve energy conversion efficiency through designs such as unequal tooth width and skewed poles.
Thermal management and control technology provide assurance for high power density. Adopting direct oil cooling or spray cooling system, the heat dissipation efficiency is several times higher than traditional air cooling by directly contacting the heating components through the cooler, solving the problem of temperature rise under high power density. Vector control technology precisely regulates the amplitude and phase of the stator current to ensure that the motor operates at the working point at different speeds, avoiding reactive power loss and further tapping into the potential of power output.