3.2.2 dynamic adjusting energy saving
With the development of electronic technology, frequency converter technology maturity, frequency converter quickly adapt to rotary joints the
load change, supply maximum efficiency voltage. Frequency conversion governor in the software has 5000 times/SEC measurement and
control output function, always keep the motor output high efficiency operation.
3.2.3 through frequency conversion own V/F function power saving:
In the guarantee motor output torque, can be automatically adjusted V/F curve. To
rotary union reduce the motor output torque, to reduce the
input current, achieve energy saving state.
We are improving power factor energy saving:
The motor stator winding and rotor winding through the electromagnetic effect and produce moment. Winding due to its inductive
reactance effect. Power to the character, impedance characteristics is perceptual and motor at run time absorb a large number of
reactive power, cause power factor is very low. The variable frequency energy saving governor, because of its performance has
become: AC, DC, AC, in rectifying filtering, load characteristic changes. Frequency conversion governor to the impedance
characteristics of the power grid is resistance sex, high power factor, reduce reactive power loss.
Four, soft start energy-saving features:
In the motor when started at full pressure, because motor start-up moment needs, from the power grid absorption 7 times of the
motor rated current, and large starting current is waste of electric power, the grid voltage fluctuation damage is very big
also, increased the line loss and variable loss. The soft start, start current can be from 0 - motor rated current, reduce the
start current for the impact of the power grid, save electricity, also reduced the start inertia of equipment large inertia
speed impact, extend the life of the equipment. Soft start controller can according to the motor power factor of high and low,
automatic judgment motor load rate. When the motor in the light or load rate is very low, but through the phase control
thyristor of conduction Angle change, so as to change the input motor power, in order to fiber optic rotary joint achieve the purpose of saving energy.
Soft starter use three instead parallel thyristor as voltage regulator, its access power and between motor stator. This circuit
such as three-phase full control bridge rectifier circuit. Use the soft starter start motor, thyristor output voltage increase
gradually, motor accelerate gradually, until the thyristor full conduction, motor work in the rated voltage of the mechanical
properties, realize smooth start, reduce the starting current, avoid start overcurrent trip. For motor achieve rated revolution,
start process is over, soft starter automatic bypass contactor replace has completed the task of thyristor, for motor normal
operation to provide voltage rating, in order to reduce the thyristor heat loss and prolong the service life of the soft
starter, improve the work efficiency, and that power grid to avoid the harmonic pollution.
High temperature superconducting motor has light weight
High temperature superconducting motor has light weight, small volume such advantages, very beneficial for ship pod propulsion applications. If a ship of 500 tons of lightweight container ship can load more than 40 containers, if using a high temperature superconducting pod propeller, then the same size of the container ship can loading 2.5% to rotary joints 4% of the container.
Figure 6 high temperature superconducting motor and conventional motor volume/power relations comparison
4 the future ship power system configuration
In the field of Marine propulsion, high temperature superconducting motor have light weight, small size, more power density and high efficiency of load characteristics, the merchant and JunChuan it is very important, meet these ship operation condition characteristics.
In addition, the high temperature superconducting motor excitation winding inner design flexible direct benefit to
rotary union ship propulsion system configuration, ship mission and all aspects of operation. Specifically, the high temperature superconducting motor may be installed in either a hold, also can be used as a pod propulsion system configuration.
According to
fiber optic rotary joint the American superconductor company plan, the future of ship electrical power systems, and electric propulsion system is not only a full power system, but also a full high temperature superconducting electric propulsion system. The whole electric power system is composed of high temperature superconducting generator power supply module, universal high temperature superconducting industrial motor user module and high temperature superconducting motor propulsion system module (figure 7).
Figure 7 full high temperature superconducting power ship power system topology
High temperature superconducting generators and high temperature superconducting motor has similar characteristics, all kinds of loss minimum, including cooling system of power loss, the whole system loss only half of the conventional generator. This makes superconducting generator efficiency increased 0.5% ~ 0.8% (superconducting generator efficiency as high as 99%). Superconducting generators synchronous reactance also small, good stability. Due to tell the core, reduced the armature winding on insulation request, therefore can adopt armature winding, save step-up transformer, can be directly into existing power grid operation. Authorities think, HTS synchronous generator is the main power plant in the future. The 5000 HP high temperature superconducting industrial motor and 5 mw high temperature superconducting Marine propulsion motor later, American superconductor company are design and development HTS synchronous generator, is for the purpose of full electric ship get application.
In the ship, high temperature superconducting motor and generator can and existing JunChuan high voltage, low current system compatible structure. Motor control can use existing synchronous/cycle, or PWM converter technology, and need not to carry on the new research and development work. The whole power system is also very quiet.
High temperature superconducting generator can be used as the ship power grid nondestructive efficiency sharpening unit to use. In the large surface ship, may be equipped with all kinds of electromagnetic weapons (electromagnetic ejection, electromagnetic gun, etc.) equipment, high temperature superconducting generators will play an extremely important role.
To drive the basic requirements of power supply
(1) drive power phase number, energizing way and the voltage and current are working to meet the needs of the stepping motor,
(2) to
rotating joint meet the stepping motor starting frequency and operation frequency requirements;
(3) can maximum limit inhibition stepping motor oscillation;
(4) work reliable, anti-interference ability;
(5) the cost is low, the efficiency high, installation and easy maintenance.
2, drive power composition
Stepping motor drive power basically by pulse generator, pulse distributor and pulse amplifier (also called power amplifier) three parts, as shown.
Into the motor drive power block diagram
(1) pulse generator
Pulse generator is a pulse frequency by a few Hector to dozens of kilohertz can the continuous variation of the pulse signal generator. Pulse generator can be utilized in a
variety of line, the most common are multivibrator and unijunction transistor a relaxation oscillator two kinds, they are all through the regulation resistance R and capacitance
C size to rotary union change capacitor charging and discharging time constant, so as to achieve the purpose of change the pulse signal frequency. Figure 6 are two practical much harmonic
oscillation circuit, they respectively by inverter and not gate structure, oscillation frequency by RC decision, change R value can change the pulse frequency.
Pulse generator practical appliances
(2) pulse distributor
Pulse distributor the gate and flip-flop composition logic circuit, it according to the instruction to the pulse signal according to
fiber optic rotary joint certain logical relationship and in the
pulse amplifier, stepping motor according to certain mode of operation work. Introduced the CH250 ring pulse distributor.
CH250 ring pulse distributor is three-phase stepper motor ideal pulse distribution
CH250 three-phase double three clap connection
CH250 ring pulse distributor is three-phase stepper motor ideal pulse distributor, through the control of the different connection can form three phase double three clap and
three phase six take different ways of working, as shown in figure 7,.
CH250 three-phase six pat connection
J3r, J3L two terminal is three-phase double three clap control end, J6r, J6L is three-phase six take control end, three phase double three clap work, if J3r = "1", and J3L =
"0", the motor is turn; If J3r = "0", J3L = "1", the motor reversal; Three phase six take power supply, if J6r = "1", J6L = "0", the motor is turn; If J6r = "0", J6L = "1",
motor reversal. R2 is double three clap the reset end, R1 is six shot the reset end, when using, first of all its corresponding reset end access high level, make it into the
work of the state, and then to change position. CL end is clock input, EN is clock pulse allows end to control clock pulse permission or not. When the pulse CP by CL end input,
only EN end for high electric at ordinary times, clock pulse rising edge to take effect. CH250 also allows to EN end for pulse CP input end, at this time, only CL for low
electric at ordinary times, clock pulse of the falling edge to take effect. A0, B0, C0 for circular distributor three output end, after pulse amplifier (power amplifier)
respectively after receiving stepping motor three-phase online.
CH250 ring pulse distributor function relations such as listed in table 1.
Table 1 CH250 menu
(3) pulse amplifier (power amplifier)
Due to pulse distributor output end A0, B0, C0 output current is small, such as CH250 pulse distributor output current is about 200-400 μ A, and stepping motor drive current is
larger, such as 75 bf001 type stepping motor each phase static current for 3 A, in order to meet the demand driven, pulse distributor output pulse subject to pulse amplifier
(that is, power amplifier) to drive stepping motor. Is a practical pulse amplification circuit in the photo, use level 3 transistor amplifier, the first level 3 dg6 small power
tube, the first secondary 3 dk4 power in the tube, and the third level 3 dd15 high power tube, R6 for stepping motor current limiting resistor, varies with the different
electric motor varies.
Pulse amplifier practical circuit
Shown is the single circuit voltage type driving power, and its features are: line is simple, resistance R6 and control winding series, can reduce loop time constant, But
because the R6 consumes power, the power of low efficiency, with this kind of power supply of the stepping motor starting and operation frequency is not too high.
High and low voltage switch drive power principle diagram
In order to improve the power efficiency and working frequency, can use high and low voltage switching type power supply, its principle as shown. High voltage power supply is
used to accelerate the speed of growth in the current, and low pressure is used to maintain the stable current value. Low voltage power supply in tandem a numerical smaller
resistance, its purpose is to adjust control winding current, make each phase current balance.
The closed-loop step become motion control scheme of one
The closed-loop step become motion control scheme of one
You are familiar with the traditional way of stepping motor control. If adopted feedback device or senseless control way, can for safety, reliability and precision higher demand movement control applied to rotary joints provide a more economical choice.
Most based on the step motor sports system are running in the open loop condition. Therefore to provide low cost solutions. In fact, step into the system is the only one not need feedback position control ability has the movement of the technology. But when stepping motor driven by the open loop way of loading, steps and actual step instructions in between the potential lost synchronization.
Closed loop control as traditional stepping motor control of supplement, for a higher safety and reliability of the product quality or the application to
rotary union provide cost-effective option. Feedback device or some indirect parameter examination way in this kind of stepping system "closed loop", in order to verify/control out-of-step, testing motor stall, and ensure a more effective torque output. Recently, stepping closed-loop control (CLC) in intelligent motion system structure distributed also play a role.
Feasible closed-loop control method and its advantages
There are several technologies can be used for step motor position, velocity, and/or torque closed-loop control. According to the control of increasing degree arrangement, these technologies include: Step back emf project. (emf) detection and all the servo control (see "closed-loop control methods", adding that the).
National Instruments (NI) company industrial control product manager Rahul Kulkarni mentioned a few to the closed loop stepping control of reason and apply occasions:
"No parameters to adjust; The system is easy to build, can generally do free maintenance.
"In the continuous motion is allowed in the use of breakpoint trigger cameras or data collection equipment.
Second-ranking position control overshoot, on some occasions this overshoot is not allowed, for example nano fabrication or semiconductor processing.
In the end correct position deviation movement.
The last one, although need according to system load and inertia asked to
fiber optic rotary joint choose appropriate size of stepping motor, but may not need so strict. "In practical work, if your application to the path or track without the strict requirements, you can slightly reduce motor specifications and grades to save costs. This is a closed loop stepping control can play a role in the first place." Unlearn said.
NI Company all the motion controller-NI 733 x (can only be used for stepping) and NI 734 x and high performance module NI 735 x (step/servo) -can be configured to step on to closed-loop control. According to his explanation, in CLC mode, stepping shaft with orthogonal encoder or analog input to the position and speed feedback.
Balder electric company thinks. The step motor is simple, cheap to make it become a location to load control ideal choice. Balder electric motor company product manager John Mazurkiewicz explained, use the step motor reasons include: the operation is simple (usually in the open loop state used); owing to accept digital pulse input and become easy and other equipment interface; low cost, because generally don't need feedback device.
However, the open loop running will bring out-of-step risk, and not cause orientation. "People perceive the mistake happened in the production line, often have a lot of defective goods," he said. "In addition, when moving a heavy load and make more step motor in maximum torque work near, and in order to improve productivity and improve the acceleration, have higher out-of-step stall risk." Increasing feedback to avoid the traditional step motor these limits.
The closed-loop stepping motor can use low cost encoder, this is relative to those in the servo system for the use of the encoder, and this leads to a further advantage: "Usually, stepping applications that use the oil encoders, and you don't need to electronic commutation feedback signal." Mayacaceae added.
According to Baldor point of view, CLC step motor light load and very short mobile particularly effective. Typical industrial applications include CNC system, process control and printing and packaging system of the X-Y table and the rotating positioning equipment.
Parker Hannifin/Compumotor company zero velocity stability requirement and position calibration of the request occasions recommend using closed loop stepping movement. "Stepping motor can well meet the requirements, and the demand is the current mainstream needs." Project manager John Walewander said. Parker had no sensor technology had a lot of investment, and has developed a patent of digital technology, it does not need additional devices external were needed for the closed-loop task, which replaced the motor of the feedback device.
Intelligent Motion Systems in its MDrive series installing a optional encoder
Intelligent Motion Systems in its MDrive series installing a optional encoder
Make motion controller and NEMA 14, 17, 23, and then the step motor micro stepping drive become one,
The figure shows the MDrive17.
The techniques--active damping and without encoder stall test-used in Parker company Gemini micro step (subdivision) drive
product family. Salamander hope for these complex algorithm further development to
rotating joints make them more efficient, so small and low
cost drive can also share these techniques. "After continuous improvement and upgrade, believe that stall detection and fight
resonance technology will and today's tiny step technologies like get popular." He concluded.
Intelligent Motion Systems Co., LTD application engineering manager Bob Parente said: "The closed-loop stepping motor can be
used to
rotary union need to confirm the position of important occasions." As an example, he cited in the automation laboratory
chemical/blood analyzer, the instrument used many moving axis will test sample positioning in the appropriate reagent
distribution device, and other stepping motor back, loading accurate number of chemical reagents, and then move forward in the
right order number and distribution of reagent-a similar to use multiple syringe process. "Any axis positioning error of many
will lead to loss of data or incorrect results." Parents said.
The increased cost of getting value for money
An additional component or system development process with extra costs. The step of closed-loop system also is such, although
get many benefits, still offers little extra costs.
"Even slightly increased the cost of feedback device, and other closed-loop motion control technology than stepping motor is
still low cost solutions." Parent explained, "to ensure the accuracy of the results, pay the extra cost is worth it. In
important applications, a mistake brought about by the cost is much higher than the losses will be the cost of the feedback
element." Encoder or the role of spin change as a kind of insurance in advance, convinced us that the step motor is working in
the correct position.
Balder company, it seems, accuracy and the improvement of the quality of parts from closed loop control, its method is in
machine or sports system for actual measurement position and the comparison of the ideal position. "If there are no consistent,
motor will campaign to compensate for any out-of-step." Missourian said. Feedback device and closed loop method are reasonable
costs and benefits will depend on the specific application. "How much to pay the extra cost of the machine performance depends
on the demand, production efficiency, position precision and of the expectations of parts quality." He added.
In addition, was charged with the value of the material in the process will also affect the balance of the cost equation. "Step
motor is often used to deal with very expensive materials, from electronic components to DNA samples." Parker wastewater said.
"To prevent a failure occurs and the increasing feedback extra cost is worth it." Parker further mentioned no sensor technology
to
fiber optic rotary joint be able to get as many of the sensors based on feedback technology advantages, and more low increase in the cost of stepping
motor control performance. Alexander added: "With a new generation of digital stepping motor control technology progress, will
be less and less dependent on external sensor feedback and cost savings for machine manufacturers."
High temperature superconducting motor to drive and control
Device did not have any special requirements. High temperature superconducting motor can use existing synchronous converter, frequency converter or PWM converter, although in order to obtain the advantage of low distortion, possible for these systems do some simplified.
2.4 economy
Reduce energy costs
High temperature superconducting motor can higher efficiency mode and low power factor mode operation (leading power factor and lagging power factor). Compared with conventional motor, a 100 mva of high temperature superconducting motor for efficiency factor, save cost could be as high as
Nearly dollars, therefore, high temperature superconducting motor operation cost relative than conventional motor is low, which in its life cycle save the energy cost.
Reduce the manufacture and installation cost
Due to the high temperature superconducting motor power density is big, can do very compact (only for conventional motor 1/3), therefore, reduce the cost of installation of the construction cost. As in the ship application, can shorten shipbuilding cycle, save fabrication cost. Likewise, small size and reduce the transportation cost.
Reduce the maintenance repair cost
High temperature superconducting motor using new rotor and output shaft design, manufacturing concept, in its operation, almost do not need to
rotary union undertake the daily maintenance.
"Queen Elizabeth ii, a luxury cruise liner is a typical example. The ship electric propulsion systems use two table 44 mw conventional motor, motor weight more than 400 tons/table. Her sister ship "queen Mary 2" in 2004 completed her maiden voyage, "queen Mary 2" propulsion power for 84 mw. If such a cruise use is now building 36.5 MW motor as propulsion motor of words, 2 sets of motor power just to satisfy her power requirements, and weight is only 1/5 of the conventional motor. Only propulsion motor a, the high temperature superconducting motor will give ship operators much economic benefits!
The United States navy estimates, the use of high temperature superconducting propulsion motor, the United States navy DDG - 51 type electric ship in normal operation condition every ship can save 450 000 dollars in operation.
Three superconducting motor and conventional motor technology comparison
To
fiber optic rotary joint compare the superconductor company 5 mw high temperature superconducting motor and other equivalent power of large motor can be found high temperature superconducting motor system is more efficient than conventional synchronous motor and advanced induction motor. Especially in low power output, its efficiency is still high, almost no changes (figure 4). High temperature superconducting motor this kind of character, just meet the ship propulsion system operating condition of demand.
Figure 4 different types of Marine propulsion motor power and efficiency curve
Figure 5 reflects the high temperature superconducting motor and the conventional motor weight/power relations comparison. Figure 6 reflects the high temperature superconducting motor and the conventional motor volume/power relations comparison, in this comparison, it also contains the quantity of maintenance. Based on the equipment itself the exterior of size and its working state, the high temperature superconducting motor simply extend 1 meter, and conventional motor must be extend 2 meters.
Figure 5 high temperature superconducting motor and conventional motor weight/power relations comparison
Propulsion motor volume and weight for ship design and construction has the important influence. If a new motor with conventional motor of the same power, and the weight or volume is only one half of that for the latter or a third, and JunChuan speaking, it means that the faster speed, more long endurance and more powerful firepower, and reliable life support. For the amount concerned, it means more effective tank capacity and greater economic benefit.
Large high voltage motor starting design
Abstract: this paper expounds the enterprise 6 kv power grid, the grid short-circuit capacity are smaller and the high voltage motor capacity is big cases starting scheme selection, starting design calculation, analysis and determination, as well as in actual driving starting data assessment, etc.
Keywords: power supply; High pressure synchronous motor; Starting; design
1 words before
Our country industrial and mining enterprises of the power supply system is a lot by 6 kv distribution voltage, in 6 kv distribution grid, if electric equipment in large capacity (2000 kv above) high voltage motor, the motor starting process, power grid voltage will produce large fluctuation, will directly affect the quality of power supply and power grid in other electric equipment normal operation and service life, this kind of situation is not allowed to appear. In order to solve this problem, in electric control design is usually adopted to rotary joints reduce motor terminal voltage way starting. Therefore, in the design, must according to the power grid conditions, for large high voltage motor starting for starting calculation, check and choose the right starting method and reasonable starting equipment.
2 grid conditions and high pressure motor of the main technical data
2.1 grid conditions
A certain air separation plant power supply electric control system from the superior decompression station, 6 kv voltage, decompression station outlet side of the maximum, minimum short circuit capacity for: Smax = 230 mva, Smin = 130 mva; Decompression station to air separation plant high pressure distribution room distance of 400 m, by two root 185 best callus induction copper core parallel feed, reduced to
rotary union air separation plant 6 kv cable into line in maximum, minimum short circuit capacity for:
Sbsmax = Sj / (Sj/Smax + XL) = 212.31 MVA
Sbsmin = Sj / (Sj/Smin + XL) = 123.46 MVA
Type of Sj - reference capacity, take 100 mva
XL - cable reactance scale MAO value, XL = 0.041 Ω
Therefore, the air separation plant 6 kva bus maximum, minimum capacity for: Sbsmax = 212.31 MVA, Sbsmin = 123.46 MVA; Air separation plant 6 kva bus for single bus section are operating, and of 3700 kw motor joint in Ⅰ period of bus to
fiber optic rotary joint the higher level, Ⅰ period of bus preliminary joint load reactive power: Qx = 2.10 MVA.
2.2 high voltage motor of the major technical data
This air separation unit using shenyang blower factory production of turbine air compressor, the drive motor as Shanghai electrical machinery plant production T3700-4/1430 large high pressure synchronous motor.
Motor parameters: rated power: 3700 kw; Rated voltage: 6 kv; Current rating: 408 a; Rated capacity: 4235 kva; Starting current multiple: six times; Power factor: cos Φ = 0.9; Frequency: 50 hz, Speed: 1500 r/min, Motor starting torque relative value: 1.8; Unit static resistance torque relative value: 0.3; Synchronous motor pull in torque relative value: 1.18; Flywheel moment: 385 kg. M2; Motor longest allow starting time: 40 s; Motor allows continuous starting number: 2 times.
