As a sales professional in the motor industry for over 20 years, when understanding technical requirements with customers, we all hope to grasp the four important performance points in the motor performance curve,

including 1. No-load (Free Load); 2. Maximum Efficiency (Max. Efficiency); 3. Maximum Output Power (Max. Output Power) and 4. Stall Torque. The performance curve is very important for motor design, reflecting the performance changes of the motor at different load points. During motor selection, it can be used to evaluate whether it meets customer needs, and what performance needs to be achieved when designing wire specifications, and whether there is a margin to pass the safety test. The differences between these four performance points are briefly introduced below.

1. No-load Point (Free Load Point): From the moment the motor is energized and starts to run, there is no load yet, the speed is at the highest point, and the motor's input current/power/output power/torque is the lowest value. It's like a person running, just starting, transitioning from static to dynamic, the body hasn't warmed up (Warm Up) yet, and the body's functions and muscle strength haven't reached their peak. In mass-produced motors, due to manufacturing tolerances, the range of no-load speed will be large. Some customers will pay close attention to whether the no-load starting current is too high to affect the control board, whether the no-load speed is too high to affect the noise, or whether the starting torque is too low, making it difficult to start under load, etc.

2. Maximum Efficiency Point (Max. Efficiency Point): From no-load to gradually loading to the motor's maximum efficiency, the motor's heat generation and mechanical losses continuously increase, inputting more current, and the speed decreases gradually. The motor's output power increases rapidly, but after this point, the growth rate of output power slows down. It is generally recommended that the customer's designed load be before the maximum efficiency point, because the energy input to the motor can be maximized for driving the rotor, and it is also the safest operating range. It's like a person running after sufficient warm-up, already in a state, not yet feeling tired, which is more suitable for continuous use without the risk of premature failure.

3. Maximum Output Power Point (Max. Output Power Point): From the maximum efficiency point to the maximum output power point, it is not recommended to use continuously in this range for a long time. Intermittent and short-time operation, plus good air convection, the motor is relatively safe. The farther away from the maximum efficiency point, the greater the input current, and the higher the chance of premature failure. Avoid the motor working at this point for a long time, as the continuously accumulating temperature will accelerate the aging of the insulating materials. If the motor has a strong odor or slight smoke after continuous operation for a long time, pay attention, and do not load close to this load point. It's like running to the middle and later stages, feeling weak, muscle soreness, and feeling very strenuous.

4. Stall Torque Point (Stall Torque Point): This refers to the state where the motor's load continuously increases to a stall state, the torque and input current reach their maximum values, but the speed drops to zero, and it cannot rotate. From the maximum output power point to the stall, this is a dangerous zone. It is strongly opposed to operating the motor under power at this point. If the thermal protector does not trip and cut off the power in advance, and the temperature of the energized part of the motor exceeds the maximum heat-resistant temperature of the insulating material, it will melt and short-circuit, and may even burn the motor windings, commutator, carbon brushes, and other parts. It's like running until the body's functions reach their limit and collapse, unable to run and falling to the ground. Some customers will pay more attention to stall torque to compare the overall motor performance.

These four motor performance points are very important for motor design. Engineers need to select a suitable motor platform based on the specific application requirements and operating conditions to ensure that the motor can achieve high efficiency, high output power, and stable operation under normal load. The consideration of these performance points can guide engineers to design suitable external dimensions, motor parameters, and control schemes to achieve optimal performance and energy efficiency. If customers can also understand the performance curve, they will have a deeper understanding of the performance of their products. Before launching the product to the market, they can conduct more simulations of user overload or long-term continuous use tests to improve the motor quality and reduce the market return rate.