Analysis of the characteristics of electric forklift motors and controllers

     The DC motor system will inevitably be eliminated in the electric forklift industry in the long run, but it is not something that will happen now. Existing large number of DC motor systems are still widely available throughout the country and even around the world. In China, vehicles will not be easily scrapped, and the maintenance market still needs a large number of DC accessories to support. The DC separately excited (or DC permanent magnet brush) motor can be electronically commutated, and it can also generate electricity at high speed, but the output torque of this type of motor is only proportional to the armature current, which is far inferior to the torque and torque of the DC series motor. The traction performance is proportional to the square of the current.

        AC motors actually refer to asynchronous motors in the domestic forklift industry. The system will become popular for a while, but the efficiency of AC motors is actually relatively poor, but its efficiency point is about 10% higher than that of DC motor systems. Asynchronous motors are well-known pseudo-energy-saving motors in the motor field, and their operating efficiency can be as low as about 50%. When the vehicle is running at low speed, the AC walking motor system may not even be as efficient as the DC motor system. In view of the inevitable need to adjust the speed in a wide range during the driving of the vehicle, the AC electronic control will also be eliminated in the long run.  

      The efficiency of the DC brushless motor is slightly better than that of the AC motor, but the use of rare earths at an acceptable price will make its torque overload capacity very poor. For small cleaning vehicles, electric motorcycles, etc. may be competent. For heavy-duty applications, At this stage, it is difficult for this kind of motor to achieve an acceptable price/performance ratio. The efficiency of the permanent magnet synchronous motor is very good. Through the reasonable utilization of the reluctance torque, the power density of a well-designed permanent magnet synchronous motor can be very large, and the power range required by the forklift is further higher than that of the AC motor. Above 10. However, permanent magnets are relatively unsound, and a good design suitable for mass production is not easy after all. There are fewer suppliers of such motors and the price is too high.   

       For the new car market, if the DC motor system can further reduce the cost of the motor and electronic control by a large margin, it will open a reasonable space with the cost of the AC system. The DC system electric car is cost-effective for rational buyers. It should still be attractive. Because of the power generation operation and electronic commutation, the performance of the series-excited electronic control is actually weaker than the efficiency for AC. As for the brush problem, it is not the main problem, because a small price fluctuation can make the motor factory easily guarantee that the carbon brush will not be replaced for 3 or even 5 years of normal use. Carbon brushes are inexpensive and easy to replace. There are too many speculators who follow the trend in the market. The irony is that in the Western electric fork market where exchanges have long been popular, there are generally rational buyers who insist on DC systems. It can be foreseen that there will be a large number of DC electric controls and motors that consume a lot of energy in old cars within 5 years. The use of series-excited motors that can continuously generate electric brakes to generate power and absorb mechanical energy and feed them back to the battery will reduce such energy consumption and contribute to the country's economy. Five years later, with the increase in the proportion of electric forks and the total amount of forklifts, and of course, with the further decline in the price of AC systems, the proportion of DC electric forks in the entire market will gradually decrease to a very small amount. Permanent magnet synchronous and other motors have gradually eroded the AC market. Perhaps the end of AC in 10 years will be the same as that of DC in 5 years. Compared with the civilian market of electric bicycles and electric tricycles, the total market for electric control of electric forklifts is not large. But the technical content of electronic control is far higher than the former. As more and more electronic control participants enter this market, it is conceivable that the price of the electronic control market will continue to decline in the future, which is estimated to be about 10 years at most.