REXRTOH VT-HPC Digital Pump Control

REXRTOH VT-HPC Digital Control Electronic Equipment: The Intelligent Core of Modern Hydraulic Pump Control Systems

In high-performance hydraulic transmission systems, the variable displacement piston pump, as the power source, directly determines the performance upper limit of the entire system in terms of control accuracy, dynamic response, and energy efficiency level. The traditional simulation control method is no longer able to meet the needs of modern industrial equipment in terms of flexibility, integrability, and intelligence. The VT-HPC (Hydraulic Pump Control) digital control electronic device launched by Bosch Rexroth is a revolutionary product designed to address this challenge. It is designed specifically for the A4VS series axial piston pump (with HS5 adjustment mechanism), deeply integrating a digital intelligent control core with powerful network communication capabilities, providing a standardized and high-performance solution for system integration from single pump control to complex hydraulic power units.

Product positioning and core features: the culmination of digital pump control

VT-HPC is not a simple driver or amplifier, but a highly integrated digital control system. Its core mission is to achieve closed-loop control of the displacement angle (inclined plate angle) and output pressure of the variable displacement pump, and integrate torque limiting function to achieve power management of the pump.

Its eye-catching core features include:

Fully digital control: using digital signal processing and advanced control algorithms to replace traditional analog circuits, achieving higher control accuracy, stability, and repeatability.

Open multi bus integration: The device comes standard with support for mainstream industrial real-time Ethernet protocols such as Sercos III, PROFINET RT, EtherCAT, EtherNet/IP, POWERLINK, and can also choose PROFIBUS DP. Switching between bus slave mode and service interface (TCP/IP) can be easily integrated into any automation architecture through parameters.

Scalable software features: Standard features include pressure and displacement angle control. By selecting different software licenses and SD cards, the variable frequency speed control function (HSS), PLC function based on IEC 61131-3 standard, and even advanced applications such as master/slave control and drag function can be activated.

Comprehensive monitoring and diagnosis: Built in comprehensive fault detection mechanism, including power undervoltage, communication errors, analog sensor cable breakage, output short circuit, and internal electronic component temperature monitoring, to ensure the reliable operation of the system.

Compliant with strict standards: The product bears the CE mark, complies with the EMC Directive 2004/108/EC, and meets the electromagnetic compatibility requirements of industrial environments.

Working principle and system architecture: precise control of hydraulic power

The core object of VT-HPC controlling A4VS pump is the electrically controlled proportional valve on the pump. The proportional valve drives the regulating piston of the pump, thereby changing the angle of the inclined plate. The core of the entire closed-loop control lies in two key feedbacks:

Displacement angle feedback: Measure the actual position of the inclined plate through a swing angle sensor.

Pressure feedback: Measure the output pressure of the pump through a pressure sensor.

The controller software of VT-HPC receives real-time set values from the upper system (via bus or analog input) and the actual feedback values mentioned above. After high-performance pressure controller and displacement angle controller calculations, it outputs control signals to drive the proportional valve. Its uniqueness lies in a minimum value selector, which ensures that at any working point, the most "urgent" controller (such as the pressure controller taking priority when reaching the pressure setting) always dominates, thereby achieving smooth control and seamless switching between pressure and flow. The actual torque value is calculated from real-time pressure and displacement angle to achieve precise torque limitation.

Deep Analysis of Hardware and Interfaces: Born for Industrial Connectivity

The hardware design of VT-HPC reflects a high degree of integration and connectivity flexibility.

1. Electrical specifications and power supply:

Working voltage: 24 VDC (range 20-28 VDC), please pay attention to the maximum allowable ripple.

Power consumption: No load current 0.2-0.4A, maximum load current 0.9-2.6A, requires external configuration of 4A delay fuse for protection.

Power loss: less than 15W (at 24V).

2. Core control performance:

Scanning cycle: The minimum scanning time of the displacement angle/pressure controller is only 0.5 milliseconds, providing a foundation for high dynamic hydraulic systems.

Start time: Less than 15 seconds from power on to control system readiness.

3. Rich I/O interfaces (provided through connectors XG20/XG21):

Digital input (4 channels): used for external commands, enable signals, etc., high level 11V-UB, each channel consumes 2-15mA of current.

Digital output (4 channels): Short circuit protection, maximum load capacity of 50mA. A key feature is that all digital outputs can be used as power pins for sensors, greatly simplifying external sensor power supply wiring.

Analog input (5-way universal+1-way dedicated swing angle sensor):

Universal input (Ai1-Ai5): can be parameterized as ± 10V voltage input or 4-20mA current input, with a resolution of 14 bits.

Dedicated swing angle sensor input (Ai_Sv): separate pin, 13 bit resolution.

Analog output (2 channels): can be independently parameterized as ± 10V voltage output or 0/4-20mA current output, with a resolution of up to 16 bits, used for outputting actual values or as a command source for other devices.

Sensor power supply: Provides UB-3V voltage for the swing angle sensor, with a maximum supply current of 60mA.

4. Valve drive output: The maximum electromagnetic current can reach 2.7A, which can directly drive high flow proportional valves.

5. Network and Communication Interface:

XF20/XF21: Two Ethernet ports with integrated switch functionality. Used for parameter settings, firmware updates, PLC programming, and as a real-time Ethernet slave interface.

XF30: (limited to models with "P") PROFIBUS DP interface, supporting a maximum speed of 12MBaud.

Software Functionality and Engineering Ecology: A Complete Toolchain from Configuration to Programming

The power of VT-HPC cannot be separated from the software ecosystem behind it.

1. Engineering software: IndraWorks

This is the core toolkit for configuring, parameterizing, and debugging VT-HPC.

IndraWorks DS: Used for equipment planning, parameter setting, debugging, and diagnosis. Its graphical interface allows users to easily configure controller parameters, select working modes, set monitoring thresholds, and more.

IndraWorks MLD: To use the built-in PLC function of VT-HPC (activated by inserting a dedicated SD card), this programming environment is required for logic and motion control programming that complies with the IEC 61131-3 standard.

2. Core control and advanced functions:

Basic control modes: pressure control, displacement angle/flow control.

Torque limitation: effectively protects the pump and prime mover, achieving constant power control.

Variable frequency speed regulation function (optional): Combined with a frequency converter, it achieves pump speed regulation, further optimizing energy efficiency, and is suitable for occasions with large changes in flow demand.

Master/Slave Control and Dragging Function: Suitable for complex hydraulic systems with multiple pumps in parallel or requiring passive following.

3. Data storage and maintenance:

The device is equipped with an SD card slot that supports up to 4GB of FAT32 format SD/SDHC cards. This card can be used for:

Save all device parameters and user data.

Store and run optional PLC programs.

Update firmware for advanced features such as variable frequency speed regulation. Rexroth recommends using its original memory card to ensure compatibility and reliability.

Installation, wiring points and LED diagnosis

To ensure stable operation of VT-HPC in harsh industrial environments, key design principles must be followed:

EMC measures: In sensitive environments, additional shielding, filtering, and other measures need to be taken.

Wiring separation: Signal lines and power lines must be laid separately as much as possible to avoid parallel wiring and reduce interference.

Shielding layer grounding: The shielding layer of all signal cables should be grounded at both ends.

Cable length limit: It is recommended that digital I/O cables should not exceed 30 meters, sensor cables should not exceed 50 meters, and valve wires should not exceed 30 meters.

Heat dissipation: The ventilation ducts above and below the device must not be obstructed to ensure sufficient heat dissipation.

The multi-color LED indicator lights on the front panel of VT-HPC are a powerful tool for rapid diagnosis:

Module Status (MS): Indicates the status of power on initialization, ready to run, activation, warning, error, etc. through different flashing combinations of red, green, and orange.

Network Status (NS): Indicates the status of the network connection.

SD card status (SD): Indicates whether the SD card exists and is ready.

Digital I/O status: directly displays the logical status of each input/output point.

Application value and industry significance

The emergence of VT-HPC digital control electronic devices has brought fundamental changes to hydraulic system design:

Simplify system architecture: It integrates previously dispersed proportional amplifiers, controllers, I/O modules, and communication gateways into a compact unit, significantly reducing cabinet space and wiring costs.

Improving performance and energy efficiency: Digital closed-loop control provides higher accuracy and dynamic performance than analog control. The integrated torque limitation and optional variable frequency function achieve energy saving of the hydraulic system from the source.

Realize intelligent and predictive maintenance: Rich status information and diagnostic data can be uploaded in real-time to higher-level monitoring systems (SCADA/MES) through the bus, providing a data foundation for predictive maintenance and process optimization.

Protecting intellectual property and simplifying spare parts: Application knowledge (such as controller parameters, PLC programs) can be stored on SD cards or protected with passwords for easy device replication and knowledge management. Standardized hardware also simplifies spare parts inventory.

It is widely used in fields with high requirements for hydraulic power control, such as large presses, injection molding machines, test benches, rolling mills, metallurgical equipment, and high-performance mobile machinery (after appropriate design).