1/29/2021

Delta’s Inverter-Driven Solution for Hydraulic Power Units Increases Energy Efficiency without Compromising Machine Performance

Hydraulic power systems are widely used as transmission gears in machinery equipment. Acting as the 'heart' of the equipment, the systems use liquid pressure to actuate machines. Among different forms of hydraulic power supply, power units are smaller and more lightweight, and simply require pipe connection for machine actuation. These features combined allow better mobility and flexibility, making the units popular power sources for machine tools and textile machinery.



Hydraulic power units are mainly composed of a pump, an oil tank, and pipes and valves, of which the pump is the power component of the transmission system. For example, gear pumps are commonly used because of their high stability and budget-friendly price. The meshing gears pump oil from the tank into the pipes, turning mechanical energy into pressure to actuate the machines.



The trickiest part of this process lies in pressure adjustment. The pressure that the machine needs changes under different conditions, requiring the motor to rotate at varying speeds. For instance, in the voltage build-up process, the motor has to operate at high speed to raise the pressure, while at the pressure holding stage, it can work at a lower speed. To change the pressure level accordingly, a variable pump is often used to automatically adjust the oil flow. However, the pressure stability is usually low and users have to live with a high level of noise, a shorter lifespan of the pump and higher costs.



Aiming to overcome these disadvantages, Delta has developed an inverter-driven hydraulic power solution for a client in central China. The solution keeps the strength of the hydraulic power unit while increasing energy efficiency with a fast pressure response. To meet the specific needs of hydraulic power units, the solution adopts and customizes Delta's Vector Control Drive. Users can read the voltage, current, and power consumption data on the Power Meter DPM Series. They can also easily adjust parameters and monitor system data through the Human Machine Interface DOP-100 Series.



It is worth noting that the Vector Control Drive, actuating the permanent magnetic motor, can automatically change the rotation speed for different pressures to meet the needs of transient states and the pressure holding process as detected by the sensor. Compared to variable pumps, this feature provides higher stability and better energy efficiency.



The solution brings the following benefits for the client:



•  Advanced multi-stage PID control automatically adjusts motor rotation speed:

The Vector Control Drive has a built-in PLC to perform multi-stage PID control in response to the constantly changing pressure level. This feature of high controllability can not only provide fast pressure response, but it can also slow down the motor’s rotation speed during the pressure holding process.



•  Production costs reduced by avoiding unnecessary energy waste:

The Vector Control Drive can automatically control the motor rotation speed to operate at a lower speed when the condition allows for minimizing energy consumption. Reducing the unnecessary high-speed operation of the motor minimizes temperature rises and extends motor lifespan. 



•  Built-in PLC reduces solution costs:

The built-in PLC of the Vector Control Drive saves the costs of adopting an external PLC.



This solution provides the advantages of hydraulic power units while overcoming the challenges of pressure response. By controlling the motor rotation speed, the Vector Control Drive can perform fast pressure response with high stability to allow higher energy efficiency. By avoiding unnecessary high-speed operation, the lifespan of the power unit can be extended. Overall, the solution allows a significant increase in machine performance with reduced costs.

News Source:IABG MKT Dept.