[ Abstract ]: For variable speed motion controlled by time, reliable speed control can be achieved using programmable frequency converters (VFDs). [ Keywords ]: VFD, speed regulation, programmable control, multi-speed operation. With the maturity of high-power thyristor manufacturing technology and SPWM modulation technology, VFD manufacturing has become a series, with low-voltage VFDs alone ranging in power from 0.4KW to 660KW. VFD speed control has a wide range of applications, involving many modern industries such as metallurgy, papermaking, printing, textiles, food, beverage, packaging, machine tools, and elevators. The application of dedicated VFDs not only solves the speed control problem but, more importantly, also offers energy-saving and consumption-reducing advantages. The diversity of general-purpose VFD control schemes and the multi-stage and stepless speed regulation capabilities have led to their wider application in industrial control. Due to various reasons, the performance of the transmissions配套 (matched/installed) with our company's battery-powered forklifts was not very stable after assembly, and the noise exceeded the standard. A long break-in period was required to meet national standards. This not only affected the response speed and delivery cycle of sales orders, but also increased the workload and labor intensity of the test operators. Therefore, we conceived the idea of ​​using frequency converter speed control to create a "battery-powered forklift transmission break-in test bench." We used the programmable multi-speed control of the Kasuga KVFC422E frequency converter on the battery-powered forklift transmission break-in test bench and achieved very significant results. Now, all of our company's battery-powered forklift transmissions can undergo break-in tests on the transmission break-in test bench. By simply modifying the control parameters, break-in programs for various tonnage transmissions can be obtained, and these programs can be updated and optimized at any time, achieving multi-purpose functionality. Figure 1 shows the break-in time and speed curve of the battery-powered forklift gearbox. The gearbox break-in process uses two-stage forward and reverse speed operation. This inverter can be set to a maximum of 8 programmable frequency segments, each independent of the others. The running time (OFF/0.16500S), acceleration/deceleration time (0.11-6500S), and frequency (0.00-5.000Hz) are all adjustable. Only the acceleration and deceleration times of each speed segment are considered for rationality. The principle of its program control is described below: the control mode specified by the function code, through multiple combinations, becomes a program step. Each program step includes: direction of rotation, set frequency, running time, and acceleration/deceleration time. Upon startup, a running command is received. Operation begins with the rotation direction and acceleration/deceleration time specified by the function code. The running timer starts counting sequentially and moves to the next timer within the specified time. If a program step is not used, its running time can be set to 0.0s. The program will then skip this program step and directly enter the next timer, directly transitioning to the next control area. The various steps and the three cyclic modes of the programmed operation work together to achieve the start and stop control of the equipment. During operation, the rate of frequency change in each segment must be limited, and the acceleration and deceleration times should not change too quickly. This is to protect the equipment from shock and to provide timely alarms in case of inverter malfunction. Since the speed is controlled by a simulated walking motor, the accuracy requirement for the rotational speed is not very strict; therefore, open-loop control is used for speed control. Full text download: Typical Application of Variable Frequency Programmable Control—Battery-Powered Forklift Gearbox Break-in Test Bench