Why Do Traditional Hydraulic Systems Waste Energy?
Hydraulic systems are widely used in injection molding machines, hydraulic presses, die-casting equipment, and many other industrial production lines. Traditional systems commonly use a fixed-speed motor to drive a hydraulic pump. The motor continues running at or near its rated speed, whether the machine is moving rapidly, maintaining pressure, or waiting for the next production cycle.
The actual demand of a hydraulic machine, however, is rarely constant. During pressure-holding, cooling, or standby stages, the required flow can be much lower than it is during rapid movement.
In a fixed-speed system, excess flow is often returned to the tank through throttling or relief valves. The energy used to produce this flow does not become useful mechanical work. Instead, much of it is converted into heat.
As the oil temperature rises, additional cooling may be required. Long-term exposure to excessive heat can also accelerate oil degradation and affect seals, valves, and other hydraulic components.
How Does Variable Frequency Control Improve Efficiency?
Variable frequency control allows the hydraulic pump to adjust its operating speed according to the actual pressure and flow required by the machine.
A pressure sensor can provide real-time feedback to the controller or variable frequency drive. When the machine requires rapid movement or high flow, the motor increases its speed. During pressure-holding, low-load, or standby stages, the motor automatically slows down.
This demand-based approach reduces throttling and overflow losses because the pump produces only the amount of flow required by the process. Motor output is therefore more closely matched to the actual machine load.
The potential energy savings depend on several factors, including the machine cycle, load profile, pump type, and original hydraulic design. Machines with significant load variation or long periods of low demand generally provide better opportunities for energy reduction.
Benefits Beyond Lower Energy Consumption
Reducing energy use is only one advantage of variable-speed hydraulic control. When less excess energy is converted into heat, the hydraulic system may also require less cooling.
Lower motor speeds during low-demand stages can reduce mechanical noise and pump wear. Smooth acceleration and deceleration may also help limit hydraulic shock, providing better protection for pipes, valves, seals, and other components.
For machines with repetitive processes, such as injection molding and pressing equipment, fast pressure response and stable torque output can support more consistent production. Different pressure, speed, and operating time settings can be applied to each stage of the machine cycle.
More precise control can also improve process repeatability. Instead of relying mainly on mechanical valves to regulate the system, the machine can combine motor-speed control with pressure feedback to respond more accurately to changing operating conditions.
Why Is Variable Frequency Control Becoming the New Standard?
Modern hydraulic equipment is increasingly expected to deliver better energy efficiency, digital control, and production flexibility. Compared with a simple fixed-speed system, a variable frequency drive can integrate pressure feedback, PID regulation, operating monitoring, and fault management into one drive platform.
When production requirements change, machine builders can adjust speed and pressure parameters without making major modifications to the hydraulic circuit. This makes it easier to adapt the same equipment to different products and processes.
Industrial communication also improves system integration. Drives can exchange operating data with PLCs, HMIs, and factory management systems. This information can support energy monitoring, fault analysis, and preventive maintenance.
Variable frequency control is therefore becoming more than an energy-saving upgrade. It is increasingly being considered during the original design of hydraulic machinery.
What Should Be Considered When Selecting a Drive?
Hydraulic systems often require high starting torque and fast dynamic response. Drive selection should therefore consider more than the rated motor power.
Low-frequency torque, overload capacity, pressure-feedback accuracy, and PID response speed are important factors. If the drive responds too slowly to a pressure command, machine movement and process consistency may be affected.
Machine builders should also consider motor compatibility, communication interfaces, fault-handling options, and reliability in environments containing heat, dust, or oil contamination.
Cooling design and maintenance accessibility are equally important. Fans and rear components that can be removed easily may reduce maintenance time and help keep the drive operating reliably over the long term.
How VFD580 and VFD586 Fit These Requirements
The VEIKONG VFD580 and VFD586 series support sensorless vector and closed-loop vector control. They can operate with asynchronous motors, permanent magnet synchronous motors, and servo motors.
Built-in process PID control, fast dynamic response, and strong low-frequency torque allow the drive to adjust hydraulic pump speed according to pressure feedback.
The series supports CAN and Modbus communication, while the VFD586 also provides EtherCAT real-time communication. An independent air-duct structure, removable cooling components, and operation without derating at ambient temperatures of up to 50°C help address conditions commonly found around hydraulic equipment.
Under suitable operating conditions, energy savings of 25% to 70% may be achievable. Actual results depend on the load cycle, pump type, original system efficiency, and drive parameters. This range should therefore not be treated as a guaranteed result for every machine.
The real value of variable frequency control is not limited to reducing electricity costs. It allows a hydraulic system to produce power according to actual demand. As equipment manufacturers place greater emphasis on efficiency, stability, and digital management, demand-based hydraulic control is becoming an increasingly important design direction.
Also read: How the VFD550I Servo Inverter Saves Energy on Hydraulic Injection Molding Machines