The allure of Chinese manufacturing lies in its continuous breakthroughs in technological barriers throughout its ongoing development—and often, it surpasses its predecessors. The variable-frequency drive, hailed as the cornerstone of modern industry, was once a field in which China lagged behind Western countries by two decades. Yet today, Chinese-made variable-frequency drives have successfully overcome those past technological limitations and achieved remarkable accomplishments.

Take the logistics industry as an example: Although foreign brands boast mature technology and enjoy clear first-mover advantages and strong brand recognition, domestically produced variable-frequency drives (VFDs) have been steadily expanding their market share in the logistics sector year after year, firmly demonstrating their competitive strength. Next, using the STEPeng VFD as a case study, we’ll explore how domestic VFDs have successfully carved out a niche for themselves in the logistics market despite the established advantages held by foreign brands.

Technical Challenges of Inverters in the Logistics Industry

In the logistics industry, variable-frequency drives (VFDs) are widely used, covering a diverse range of machinery—from conveyor belts and sorting systems to stackers and cranes. These specific application scenarios place extremely high demands on the performance of VFDs, making the technical challenges that need to be overcome particularly clear.

Difficulty 1: The ability to precisely control the speed and position of cargo movement.

STEP Technology: Dual-Loop Control Technology
Simultaneously employing both velocity and position feedback loops, the velocity loop is used for rapid, real-time acquisition of the motor speed, while the position loop acquires the mechanical absolute positioning. This constitutes a dual-loop control system that, through an efficient algorithm, achieves stable and balanced current-torque control while maximizing motor efficiency.

Difficulty 2: When using the automated warehouse lift, it should be able to prevent bottom and wheel jamming caused by cargo entering or exiting the cabin and resulting in positional shifts.

STEP Technology: Dynamic Leveling Function
Based on the existing mechanical transmission and motor configuration, and leveraging dual-loop control technology that combines a speed loop with a position loop, while simultaneously activating the software feature for dynamic leveling, the system relies on its powerful zero-speed hovering capability to ensure the stability of the four-way in-and-out cargo elevators installed on vehicles.

Challenge No. 3: Under the premise of ensuring smooth cargo transportation, reach the destination in the shortest possible time.

STEP Technology: Direct Docking Algorithm  
The dynamic programming position curve ensures the shortest possible time to reach the target position. The position curve undergoes a second-order FIR filtering to generate smooth acceleration, guaranteeing stable cargo transportation. Upon reaching the destination, position calibration is performed in conjunction with level-limit switches, ensuring that the final leveling accuracy is within ±1 mm.

Challenge No. 4: Preventing load swing and enhancing efficiency and safety

STEP Technology: Anti-Roll Function
Due to the pendulum system formed by the inertia of the suspended load and the suspension cable, the load will swing during operation—especially during the acceleration and deceleration phases. Load swinging during crane movement is a very serious and common issue that can impair operational efficiency. The anti-swing function employs a triple mechanism to effectively suppress oscillations, thereby preventing the load from swinging when the trolley or hoist is accelerating or decelerating.

Difficulty 5: Easy Debugging

STEP Technology: Host Computer Software + Servo Control Module  
Parameter settings for the frequency inverter are critical to its proper operation. Incorrect settings not only may prevent the inverter from functioning normally but, in some cases, could even damage the inverter itself. Host computer software: A customized commissioning wizard tailored specifically for the logistics industry, guiding customers through on-site debugging procedures; dynamic self-learning capability that eliminates the need to input mechanical gear ratios and wheel diameters, automatically calculating the rated linear speed; servo control blocks: Pre-packaged servo control blocks designed according to users’ programming habits, providing ready-to-use references for customers. This approach saves time during commissioning and reduces programming effort. When users replace their existing ET6L frequency inverter with a new one, they simply need to drag the variables from the original program onto the corresponding pins of the control block and make minor program adjustments to enable the ET6L inverter to operate in position-control mode.

The intelligent and flexible ET6L series variable-frequency drives specially designed for the logistics industry represent the latest-generation drive product developed by STEP in response to current market characteristics and demands in the logistics sector. These are versatile drive products tailored for industrial production processes, inheriting the cutting-edge design philosophy of the latest generation—streamlining complexity into simplicity—and effectively boosting your production efficiency. While overcoming the five technical bottlenecks mentioned above, the intelligent and flexible ET6L series VFDs for the logistics industry... Based on the actual application and walking waveform data of the frequency converter, the technology has reached an advanced level in the industry.

Application of Inverters in the Logistics Industry
Inverters play a crucial role in various mechanical equipment across the logistics industry. Their application is particularly critical in the following logistics equipment:

Elevator  

The frequency converter can precisely control the hoist’s speed and acceleration, ensuring smooth lifting and lowering of goods while preventing mechanical shocks and vibrations caused by changes in speed.

Stacker crane

Stackers are primarily used for the automated stacking and retrieval of goods in warehouses. The use of frequency converters enables stackers to operate at low speeds with precise control, which not only ensures operational accuracy but also reduces mechanical wear and enhances overall operational efficiency.

Crane

During material handling, cranes need to move heavy objects at varying directions and speeds. By using a variable frequency drive (VFD), the crane’s starting, running, and stopping speeds can be smoothly adjusted steplessly, enabling smooth starts and stops while preventing load swinging and mechanical shocks.

Conveyor line

The frequency converter can precisely control the speed of the conveyor belt, reducing equipment failures caused by issues such as overload and overheating, thereby enhancing the system’s reliability and stability. Additionally, by adjusting the voltage and frequency of the output power supply, the frequency converter can also lower energy consumption.

Click to learn more: Additional product information on the STEP ET6L series variable frequency drives specifically designed for the logistics industry.

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