Electro-hydraulic servo control system

Abstract

The invention relates to the technical field of controllers, and discloses an electro-hydraulic servo control system which comprises a permanent magnet synchronous servo motor, a servo driver, a pressure sensor and a hydraulic system. The permanent magnet synchronous servo motor is used for driving the hydraulic system; the servo driver is in signal connection with the pressure sensor and the permanent magnet synchronous servo motor; the pressure sensor is arranged in a hydraulic system and used for detecting the pressure of the hydraulic system, and the permanent magnet synchronous servo motor adopts a high-permeability low-loss silicon steel sheet and a special high-frequency winding to prepare a stator. In the aspect of energy conservation, the effect is remarkable, a permanent magnet synchronous servo motor and an electro-hydraulic control integrated electrical system are adopted, and the energy conservation rate reaches 20%-25%; dynamic pressure output control greatly reduces invalid power consumption loss, servo system pressure and flow double closed loops, oil is supplied according to actual requirements, the rotating speed of the motor is reasonably adjusted in different working stages, the actual energy consumption of the oil pump motor is reduced by 15%-30%, and economic benefits are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of controllers, in particular to an electro-hydraulic servo control system. Background Art

[0002] The electro-hydraulic servo system can give full play to the advantages of both electronics and hydraulics, has good flexibility and adaptability, and has been widely used in industrial process control. With the development of industrial technology, the requirements for the performance and technical indicators of electro-hydraulic servo controllers are getting higher and higher. As an important component of hydraulic complex simulators, the performance of electro-hydraulic servo controllers directly affects the performance of hydraulic complex simulators.

[0003] The traditional extruder hydraulic system uses a three-phase asynchronous motor as the drive system. During the normal production process of the extruder, there is unnecessary power loss, which leads to a series of negative effects such as increased oil temperature in the hydraulic system, unstable pressure, and easy damage to seals. At the same time, traditional equipment also generates noise during use. For this reason, an electro-hydraulic servo control system is introduced. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides an electro-hydraulic servo control system that solves the problems raised by the above-mentioned background technology.

[0005] The present invention provides the following technical solutions: an electro-hydraulic servo control system, comprising a permanent magnet synchronous servo motor, a servo driver, a pressure sensor and a hydraulic system; The permanent magnet synchronous servo motor is used to drive the hydraulic system; The servo driver is connected to the pressure sensor and the permanent magnet synchronous servo motor signal; The pressure sensor is arranged in the hydraulic system and is used to detect the pressure of the hydraulic system.

[0006] Preferably, the servo driver is used to receive a pressure signal detected by a pressure sensor.

[0007] Preferably, the permanent magnet synchronous servo motor adopts a stator made of high magnetic permeability, low loss silicon steel sheets and special high-frequency windings, the permanent magnet synchronous servo motor adopts a rotor made of high-performance neodymium iron boron magnets, and the permanent magnet synchronous servo motor is equipped with one of a sinusoidal photoelectric encoder, a multi-turn magnetic encoder, and a rotary transformer as a feedback device.

[0008] Preferably, the hydraulic system includes an oil pump, and the oil pump type can be selected from screw pumps, plunger pumps, and gear pumps.

[0009] Preferably, the low-speed pressure-maintaining performance of the servo drive is improved by 50% compared with the original one, and the achievable indicators are that under a pressure of 140kgf, the pressure fluctuation is controlled at 0.5kgf when the oil pump speed is 20rpm; the response time when the pressure starts at 175kgf is 30ms, the pressure overshoot is 3kgf, the pressure relief time is 50ms, and the pressure oscillation is 1kgf.

[0010] Preferably, the servo driver receives the pressure sensor signal through the analog input port and has a built-in PID adjustment algorithm, which can compare the actual pressure with the set pressure in real time.

[0011] Preferably, the servo drive adopts the fourth-generation KT4 IGBT module, and the busbar capacitor adopts a capacitor with wider temperature adaptability and longer service life.

[0012] Preferably, the pressure sensor indicator is 0-250kgf / cm2----------0—10vdc, or 1--5VDC, or 4-20MA.

[0013] The present invention has the following beneficial effects: 1. The electro-hydraulic servo control system has significant energy-saving effects. It adopts a permanent magnet synchronous servo motor and an electro-hydraulic control integrated electrical system, achieving an energy saving rate of 20% to 25%. Dynamic pressure output control significantly reduces ineffective power loss. The servo system has a double closed loop of pressure and flow, supplies oil according to actual demand, and reasonably adjusts the motor speed in different working stages, reducing the actual energy consumption of the oil pump motor by 15% to 30%, significantly improving economic benefits.

[0014] 2. This electro-hydraulic servo control system improves the working environment. The permanent magnet synchronous servo motor reduces the equipment operating noise. After the transformation, the overall noise is ≤80 decibels, which improves the comfort of the workshop working environment and has many benefits for the equipment life. The system achieves nearly zero current standby operation in the standby control state, reducing motor aging due to heat and increasing the motor's service life. It can effectively control the system temperature during operation, avoid seals from aging due to high temperature, and reduce the loss of components such as motors and seals. In terms of maintenance costs, the system temperature is effectively controlled, which reduces seal aging, leakage and pressure instability, thereby reducing the daily maintenance costs of the equipment.

[0015] 3. The electro-hydraulic servo control system has also improved production efficiency and product quality. The servo response speed is fast, and the pressure and flow rise time is as fast as 20ms, which improves the response speed of the hydraulic system, reduces the action conversion time, speeds up the operation rhythm of the whole machine, and improves production efficiency; the servo adjustment capability is strong, and the pressure closed-loop control makes the system pressure stable, with a fluctuation of less than ±0.5kg, which improves the product molding quality, and the shooting platform movement position repeatability is high, the product precision and consistency are good, the scrap rate is reduced, and material waste is reduced. In addition, the system is highly adaptable and can be equipped with a variety of oil pumps, which is convenient for users to select according to different products; the high integration reduces the difficulty of electrical assembly and procurement, and is easy to use. Ordinary technicians can quickly debug parameters through the digital panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the circuit modification structure of the present invention; Figure 2 This is a schematic diagram of the servo hydraulic system architecture of the present invention; Figure 3 This is a schematic diagram of the structure of the pressure and flow control algorithm of the servo driver of the present invention; Figure 4 This is a schematic diagram of the multi-pump separate / parallel flow control structure of the present invention. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0018] See also Figure 1-4 , an electro-hydraulic servo control system, comprising a permanent magnet synchronous servo motor, a servo driver, a pressure sensor and a hydraulic system; Permanent magnet synchronous servo motor is used to drive the hydraulic system; The servo driver is connected to the pressure sensor and the permanent magnet synchronous servo motor signal; The pressure sensor is arranged in the hydraulic system to detect the pressure of the hydraulic system.

[0019] The servo driver is used to receive the pressure signal detected by the pressure sensor.

[0020] Among them, the permanent magnet synchronous servo motor uses a stator made of high-magnetic permeability, low-loss silicon steel sheets and special high-frequency windings, the permanent magnet synchronous servo motor uses a rotor made of high-performance neodymium iron boron magnets, and the permanent magnet synchronous servo motor can be equipped with one of the sinusoidal photoelectric encoders, multi-turn magnetic encoders, and rotary transformers as feedback devices.

[0021] These structures give the motor advantages of small size, low inertia, high rigidity, high efficiency, low noise, fast response, smooth operation, precise control, and strong overload capacity. The motor power factor can reach 1, which can save considerable energy in continuous fixed load operation. The power saving effect is particularly significant in continuous periodic load operation, saving about 30% more energy than traditional motors (depending on the specific working conditions), thus achieving the goal of energy conservation and emission reduction. The stator adopts the block-type process, which has high production efficiency, material saving, mechanized winding and good reliability; The unique method of fixing the rotor permanent magnets not only has a certain magnetic resistance torque, but also ensures the safety of the high-speed rotating permanent magnets, making them less likely to fly out due to centrifugal force. The optimized magnetic circuit design ensures the overload capacity at high speed and high torque, which is particularly suitable for the process requirements of the extruder, especially in the sol stage.

[0022] Among them, the hydraulic system includes an oil pump, and the oil pump type can be selected from screw pumps, plunger pumps, and gear pumps.

[0023] The speed of the screw pump is 2000-2200 rpm, with a maximum flow rate of 125CC. However, in actual application, the reliability decreases when the speed exceeds 1800 rpm, and the requirements for oil source and oil quality are stringent. The modified machine is generally an old machine, and the oil quality is difficult to guarantee. It is often necessary to maintain pressure at a speed of dozens to hundreds of rpm, and new hydraulic oil needs to be replaced; The speed of the plunger pump is 1500-1800 rpm. Due to the reciprocating motion of the 9 plungers, the oil supply is not as continuous as that of gear pumps and screw pumps. The oil pressure fluctuates easily, and the oil quality requirements are high. In addition, the mechanical structure is complex, there are many moving parts, and the noise is the loudest among all pumps. The gear pump has a rotation speed of 1500-2200 rpm and uses the gaps between teeth to drain oil. It has low requirements on oil quality, low manufacturing cost, simple process and stable system.

[0024] The hydraulic system also adopts parallel pump technology, which is divided into two schemes: "multi-pump parallel flow" and "multi-pump split / parallel flow". Multi-pump parallel flow means that one set of servo oil pumps is used as the master drive, and the remaining oil pumps are used as slave drives to work in parallel, with consistent action and start and stop. The master and slave drives are connected via the CAN bus (or pulse mode) to ensure the same motor speed; multi-pump split / parallel flow means that two sets of servo oil pumps can work in multi-pump parallel mode and multi-pump split (individual control) mode. The master and slave drives can be controlled accordingly through the X4 / X5 multi-stage linkage split and parallel flow control terminals.

[0025] Among them, the low-speed pressure-maintaining performance of the servo drive is improved by 50% compared with the original. The achievable indicator is that under a pressure of 140kgf, the pressure fluctuation is controlled at 0.5kgf when the oil pump speed is 20rpm; the response time when the pressure starts at 175kgf is 30ms, the pressure overshoot is 3kgf, the pressure relief time is 50ms, and the pressure oscillation is 1kgf.

[0026] Among them, the servo driver receives the pressure sensor signal through the analog input port, and has a built-in PID adjustment algorithm, which can compare the actual pressure with the set pressure in real time.

[0027] The servo response speed is fast, and the pressure rise time and flow rate rise time are as fast as 20ms, which improves the response speed of the hydraulic system, reduces the action conversion time, and speeds up the operation rhythm of the whole machine; When the hydraulic system of the extruder is running automatically, when a valve is opened, the system pressure will drop instantly. The oil can be quickly replenished within 20ms to restore the pressure to the set value. Among them, the servo drive adopts the fourth-generation KT4 IGBT module, and the bus capacitor uses capacitors with wider temperature adaptability and longer service life.

[0028] The fourth-generation KT4 IGBT module has a lifespan 2.5 to 3 times longer than the third-generation one. The KT4 module is more stable, has a small thermal margin, and a high junction temperature, which greatly improves the stability of the equipment. The use of capacitors with wider temperature adaptability and longer service life increases the theoretical life by 4 times; the new capacitor design and selection enhances the ability to absorb power grid shocks and drops, greatly improving product stability.

[0029] Among them, the pressure sensor indicators are 0-250kgf / cm2----------0—10vdc, or 1--5VDC, or 4-20MA.

[0030] Improve sealing through 1 / 4PT pipe thread; The pressure sensor uses a plug-type wiring method, which is convenient for users to connect; And in the renovation project, it is necessary to reserve an installation port on the flange block of the oil outlet.

[0031] Oil pump selection: The two most important parameters of the extruder are pressure and flow, so when we configure a new servo system, the pressure and flow of the new servo system cannot be smaller than those of the original extruder.

[0032] Calculate the original extruder flow rate (L1) = oil pump displacement (ml / rev) × original motor speed (R / min) × pump volumetric efficiency value ÷ 1000. When considering volumetric efficiency, the volumetric efficiency is generally = 0.9 or refer to the pump catalog. In general, the calculation does not need to consider volumetric efficiency, and its value = 1; Calculate the new servo system oil pump displacement q (ml / rev) = L1 ÷ 2000 (new servo motor speed) × 1000; Selection of servo motor: The general principle for motor selection is the oil pump displacement and system pressure, because an oil pump of a certain displacement must be pressurized to a certain pressure, which determines the torque that the motor should provide.

[0033] According to hydraulic principles: the maximum torque that the motor should provide Tmax=0.0159*P*q(NM); Where P is the system pressure - kgf / cm2, q is the oil pump displacement - cc / rev Working conditions and overload; Since the extruder is rarely fully loaded during a working cycle, it works at high speed and low pressure or high pressure and low speed most of the time. At the same time, since the motor itself has a strong overload capacity, it is appropriate to take 1.5 times the overload capacity.

[0034] Therefore, the rated torque of the motor should be: Tm=Tmax / 1.3---1.5; Servo drive: The driver should be selected based on the current principle, not the power matching principle. When the servo drive drives the oil pump, the following characteristics are obvious: The load current is proportional to the displacement of the oil pump, which can be obtained from the formula; The load current is proportional to the oil pump pressure, which can be obtained from the formula; The load current is inversely proportional to the rated speed of the motor, which can be obtained from the description of torque and torque coefficient in motor science.

[0035] T=9550xPpower / nspeedT=0.0159xPpressure / qdisplacementKT=rated torque / rated current; According to the formula for the required torque of the oil pump and the KT value of the motor, the maximum current of the motor can be calculated as I=T / KT; According to the overload capacity of the driver, the time for overload of 1.5 times is 1 minute, and it can work for a long time if the overload is less than 1.5 times.

[0036] The servo system has a double closed loop of pressure and flow, and the hydraulic system supplies oil according to the actual required flow and pressure, overcoming the high energy consumption caused by high-pressure overflow of ordinary quantitative pump systems. The motor operates at the set speed during high-flow working stages such as feeding and extrusion molding, and reduces the motor speed during low-flow working stages such as preheating, shaping, and traction. The actual energy consumption of the oil pump motor is reduced by 15%-30%.

[0037] Working principle: Speed ​​N controls flow. When the flow establishes pressure, PID controls speed to stabilize oil pressure (i.e. flow and pressure are controlled by speed). When oil pressure is not established, there is still space in the pipeline. At this time, the oil pump is operated in a manner proportional to the flow and speed. The pipeline quickly flushes oil, and the oil will be restricted by the pipeline and quickly build up oil pressure. After the oil pressure is established, the speed N adjusted by PID is used for control. Due to the balancing principle of PID, the oil pressure can be stabilized at a given value.

[0038] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0039] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An electro-hydraulic servo control system, characterized in that: Including permanent magnet synchronous servo motor, servo drive, pressure sensor and hydraulic system; The permanent magnet synchronous servo motor is used to drive the hydraulic system; The servo driver is connected to the pressure sensor and the permanent magnet synchronous servo motor signal; The pressure sensor is arranged in the hydraulic system and is used to detect the pressure of the hydraulic system.

2. The electro-hydraulic servo control system according to claim 1, characterized in that: The servo driver is used to receive a pressure signal detected by a pressure sensor.

3. The electro-hydraulic servo control system according to claim 1, characterized in that: The permanent magnet synchronous servo motor adopts a stator made of high-magnetic permeability, low-loss silicon steel sheets and special high-frequency windings, and the permanent magnet synchronous servo motor adopts a rotor made of high-performance neodymium iron boron magnets. The permanent magnet synchronous servo motor is optionally equipped with a sinusoidal photoelectric encoder, a multi-turn magnetic encoder, or a rotary transformer as a feedback device.

4. The electro-hydraulic servo control system according to claim 1, characterized in that: The hydraulic system includes an oil pump, and the oil pump type can be selected from screw pumps, plunger pumps, and gear pumps.

5. The electro-hydraulic servo control system according to claim 1, characterized in that: The low-speed pressure-maintaining performance of the servo drive is improved by 50% compared with the original one. The achievable indicators are: under a pressure of 140kgf, the pressure fluctuation is controlled at 0.5kgf when the oil pump speed is 20rpm; the response time when the pressure starts at 175kgf is 30ms, the pressure overshoot is 3kgf, the pressure relief time is 50ms, and the pressure oscillation is 1kgf.

6. The electro-hydraulic servo control system according to claim 1, characterized in that: The servo driver receives the pressure sensor signal through the analog input port and has a built-in PID adjustment algorithm, which can compare the actual pressure with the set pressure in real time.

7. The electro-hydraulic servo control system according to claim 1, characterized in that: The servo drive adopts the fourth generation KT4 IGBT module, and the bus capacitor adopts a capacitor with wider temperature adaptability and longer service life.

8. The electro-hydraulic servo control system according to claim 1, characterized in that: The pressure sensor indicators are 0-250kgf / cm2----------0—10vdc, or 1--5VDC, or 4-20MA.

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