DYNAMIC LOAD REGULATING DEVICE Field of the invention
The present invention relates to a dynamic load regulating device for process machines such as ring spinning textile machines or any other machine which is dependent on regular and uninterrupted power supply. More particularly, the present invention provides a dynamic load regulating device for use in process machines which require that a specific amount of power be provided constantly without power surges or power reductions. Background of the invention
Regular maintenance of power load in process machines is of critical importance. Power outages adversely affect manufacturing conditions and result in the inevitable shortage of production. More importantly, while modern day process machines are protected against upsurges of power load using stabilizing equipment, there is no provision for ensuring a continuous supply of desired power load to a process machine. Thus, if the load falls below the normal requirement of a particular process machine, the manufacturing may again slow down and the equipment suffers tremendous damage.
For example, textile machines such as ring spinning machines require an extremely even run and precise speeds of driven work elements. They also require defined revolution and/or speed relationships for the driving elements. There are certain important prerequisites for a spinning machine. For example, the relation of the revolutions of the spindle to the supply speed is decisive for the spin and the tenacity of the yarn in order to maintain an even draft. The revolution values of the cylinders of the drafting arrangement must also be in a defined relationship to one another. Also, the movement speed of the ring rails, for example, as well as the relationship of this speed to the preceding speed is of importance for the yarn package formation on the bobbin. These are essential to maintain a uniform yarn quality. Therefore it is also important to maintain a constant power supply. As each of the work elements of the ring spinning machine should be separately selectable in order to achieve a higher variability, rigid geared connections between these work elements should be avoided if possible. Each power failure brings about an extreme danger of thread breakage, because the drafting arrangement will generally come to a standstill while the spindles keep on turning due to their inherent inertia.
It is known in spinning/ twisting machine that the kinetic energy of the spinning or twisting organs, i.e., spindles, is, in case of power failure, exploited for energy recuperation and for the supply of the work elements which normally come to a quicker
standstill. For this, the electric motors of the spinning or twisting organs function as generators. In such machines, recuperation takes place up to the standstill of the work elements, in particular of the drafting arrangement. However, there exists the danger that in the lower revolution range close to zero, the driving motors to be supplied with emergency power can no longer be controlled or precisely selected. With frequency controlled synchronous motors, for example, the produced moment is dependent on the square of the voltage/frequency relationship. If the corresponding critical values are undershot, the motor comes off shot which in general leads to the immediate standstill of the aggregate in question, for example of a drafting arrangement. Given that the spinning or twisting organs with the greater effective inertia keep on turning, inadmissible changes of the yarn twist or thread breaks may result despite the emergency power supply.
In other conventional textile machines, a similar battery backing of the affected driving systems takes place immediately after the appearance of a power failure. However, one particular disadvantage of this is that the batteries providing the emergency supply must be correspondingly large-sized.
Development and application of computer technology has created a demand for a variety of power protection devices ranging from high isolation transformers to large scale uninterruptible power supply systems. For many years, the basic system for providing a buffered or protected AC power supply was a simple motor generator set. An example of such a buffered supply is the power conditioning system employing a motor generator set that is sold by the assignee of the present invention under the name POWERBLOC. Use of a motor generator set has proven to be a reliable method of protecting a computer from harmful effects of voltage fluctuations and brief power outages. The motor generator set provides isolation of the load from electrical noise and power protection during outages up to about five seconds in duration. However, for those systems, including many large scale computers, that require protection from power outages of greater duration, an alternate or emergency power supply is required to provide power for a period long enough to generate an alarm and allow the operator to shut down or otherwise protect the load from power loss. Various types of emergency power or uninterruptible power supply systems have been employed, but these commonly require on-line operation of all or at least major portions of the auxiliary system. For example, a system has been employed in which a rectifier and inverter are series connected in the main power supply to the motor generator that drives the load, with the inverter being operable by an auxiliary battery for emergency power. The relatively low efficiencies of the inverter and rectifier, which must operate
continuously in such prior arrangement, are wasteful of energy. The on-line system is more costly and has decreased reliability because of its required continuous operation. Even an off-line, standby inverter is inefficient and wasteful of energy if it must operate during normal power operation.
Installation of a power conditioning system having an uninterruptible power supply of a size sufficient for a given load requirement may be a factor limiting expansion of the load. An increase in the power required by the load (by the addition of other computers, for example) may require the uninterruptible supply system to provide power beyond its capacity. Therefore, increased load may require use of a larger substitute or an additional uninterruptible supply system with significantly increased cost, inefficiency and reliability problems. Frequently, an original, relatively smaller uninterruptible power supply must be replaced with a larger system to allow expansion of load power requirement. There are no known emergency standby power systems that can be readily and inexpensively retrofitted to existing motor generator power conditioning systems, nor which operate as true standby systems wherein a normally nonoperating inverter is driven only during main line power outage.
US Patent 5,113,123 discloses a ring spinning machine wherein various driving systems for driving spindles, driving arrangements, ring rails and the like is regulated in the case of power failure down to a zero revolution range while maintaining preselected revolution relationships. The driving system which is allocated to the load with the greatest effective inertia serves, at first, for the supply of the other driving system in a generator service. Only in a lower revolution range are the driving systems backed via a battery of relatively low capacity.
United States Patent 4,617,497 discloses a Spinning or twisting machine control system wherein an emergency battery power supply for a ring-spinning or ring-twisting frame can be brought into operation by an automatic circuit to bridge brief power failures and effect programmed shutdown of the motors upon longer power failures, with the speed ratios between the motors being maintained substantially to standstill to avoid yarn breakage during shutdown.
United States Patent 4,471,233 discloses an emergency power system comprising a motor generator set that is used to provide clean, noise-free power to a load, such as a computer, is upgraded to a complete uninterruptible power supply by the addition of a logic controlled, battery powered inverter that is readily connected in the main power supply line to the motor generator. The emergency power inverter operates only when
normal utility power fails, and employs the ability of the motor generator set to handle brief power outages to power the load for the brief time needed to decouple the main line power supply and couple the inverter to the motor generator. An oscillator that clocks trigger pulses for the inverter tracks motor voltage frequency and phase until power is supplied to the motor from the standby inverter. Switching to the emergency power inverter is accomplished by detecting both reverse power and zero current. In the Ring Spinning machine the load of the machine increase as bobbin size increases with time. This happens as more yarn accumulates on the rotating bobbin. The heavy the weight of the moving part more is the requirement of the power.
In ring spinning machines the load of the machine increase as bobbin size increases with time. This happens as more yarn accumulates on the rotating bobbin. The heavier the weight of the moving part more is the requirement of the power. Variations in power such as surges are administered by existing systems which regulate the power load input to the process machine. However, there has been felt a need to provide shortfalls in power when the load becomes higher due to any factor such as increase weight of the moving equipment. It is known in the art to attempt to solve the latter problem by running the machine on the fix maximum possible speed at maximum load or decreasing the speed in step with the progress of doff. However, these methods suffer from several disadvantages which are enumerated below:
• Machine either runs at lower speed than desired or overloads the motor.
• With such systems, even theoretically maximum possible efficiency cannot be achieved
• Frequent short term overloading reduces the life of the motor.
• Frequent tripping of the motor safety devices not only reduces the life of electrical switchgears but also result in production loss.
• The parameters set to get maximum machine efficiency changes with many factors like product size, product material, supplied voltage, machine wear and tear, environmental temperature and humidity etc.
• Replacing motor and inverter to higher size is not always commercially viable due to high price and low efficiency of these at lower load conditions.
Objects of the invention
Accordingly, it is an object of the present invention to provide an emergency power system that avoids or minimizes above-mentioned problems.
It is another object of the invention to enable a ring-spinning machine to continue in response to a power failure without the need for costly equipment.
It is another object of the invention to provide a relatively simple control arrangement for continuing a ring spinning machine in response to a power failure. Summary of the invention
The present invention provides a control arrangement for supply of power to a process machine such as a ring spinning machine in response to requirements of varying power. The present invention provides a relatively simple and inexpensive control arrangement for power regulation to a textile machine in response to for example, a power failure or equipment overload.
In any process machine where load varies, a constraint to maximum speed exists due to the varying load. The power load regulating device of the invention continuously monitors the load of the machine and controls the sped dynamically based on the load and/or the machine requirement. The device eliminates the drawback of running the machine at low speed due to variation in the load. The device is also dynamic and flexible and can be applied where the machine can run at higher speed but is unable to do so due to motor capacity. Brief description of the accompanying drawings
Figure 1 is a block diagram of a conventional load regulating method.
Figure 2 is a block diagram of the load regulation using the device of the invention.
Figure 3 is a block diagram of the device of the invention showing the various components of the device of the invention.
Figure 4 is a detailed representation of the comparator circuitry of the device of the invention.
Figure 5 is a detailed representation of the circuitry of the pulser component of the device of the invention.
Figure 6 is a detailed representation of the circuitry of the maximum limit monitor component of the device of the invention.
Figure 7 is a detailed representation of the circuitry of the minimum limit monitor component of the device of the invention.
Figure 8 is a detailed representation of the circuitry of the power supply which is regulated by the device of the invention.
Figure 9 is a detailed representation of the circuitry of the counter component of the device of the invention.
Figure 10 is a detailed representation of the circuitry of the digital to analog converter component of the device of the invention. Detailed description of the invention
The present invention provides a control arrangement for supply of power to a process machine such as a ring spinning machine in response to requirements of varying power. The present invention provides a relatively simple and inexpensive control arrangement for power regulation to a textile machine in response to for example, a power failure or equipment overload. While the invention is described hereinbelow with reference to a textile ring spinning machine, the power load regulator is applicable in any environment where varying load requirements may exist.
In any process machine where load varies, a constraint to maximum speed exists due to the varying load. The power load regulating device of the invention continuously monitors the load of the machine and controls the sped dynamically based on the load and/or the machine requirement. The device eliminates the drawback of running the machine at low speed due to variation in the load. The device is also dynamic and flexible and can be applied where the machine can run at higher speed but is unable to do so due to motor capacity.
The invention will now be described with reference to the accompanying drawings. Figure 2 is a block diagram of the method by which the device of the invention functions in ensuring a regulated power supply dependent on load of the process machine. As shown in figure 2, the machine control box 1 is connected directly to the dynamic load regulator 2 of the invention. The dynamic load regulator is in turn connected to a inverter 3 through which a control voltage is provided to the dynamic load regulator 2. The load controller is also connected to a motor 4 by passing the inverter 3 through a transducer 5. The dynamic load controller varies the speed of the machine depending on the current load of the motor and thereby protects the motor from being overloaded. The load controller monitors the maximum and minimum load requirements of the process machine 1 constantly and inputs these signals to the inverter and the motor. Therefore, when the load requirement is high, the load controller slows the process machine and when the motor is overloaded, it speeds up the machine. The demand of the process machine is also taken into consideration. The load controller signals the motor/main power supply in case of overloading. The device of the invention uses digital signaling methodology and therefore is impervious to noise generated by the inverter and motor.
The control voltage which drives the inverter, is forced to pass through the device of the invention. The device of the invention does not interfere with the input signal unless the motor load exceeds the prescribed limit. The load controller does not increase the control voltage. Instead, it lowers the speed of the machine to the level just below the overloading of the motor.
Referring now to figure 3 which provides a block diagram of the load regulator, the device primarily comprises of a digital electronic circuit, which controls the analog signal of zero to ten Volt DC. The comparator component of the load regulating device of the invention comprises two operational amplifying means (C1, C2) which form an open loop to provide a logical output. The operational amplifiers (C1, C2) test the input against predefined lower and upper limits. The upper and lower limits for the input are preset depending on the process machine. The operational amplifiers are connected in turn to a pulsation means comprising two pulsers (P1, P2). Pulsers P1 andP2 are in turn connected to separate dedicated limit monitoring means L1 and L2. L1 and L2 monitor the maximum limit and the minimum limit respectively. This is explained with reference to Figure 6 and Figure 7 subsequently herein. Both the monitors are connected in the form of a loop and also to a pulse counter (PC) which is in turn connected to an analog to digital converter (AD). The analog to digital converter (AD) is connected at one end to a control voltage input and at the other end to a control voltage output.
The operation of the device of the invention will now be explained with reference to Figures 4 to 10 which provide the individual circuit diagrams of the various components of the device of the invention.
Figure 4 is a representation of the circuit diagram of the comparator component of the invention. As explained above with reference to figure 3, the comparator component comprises essentially of two operational amplifiers. The input voltage from transducer (41) is converted into DC with four diodes (IN4007) and a capacitor (10µF). Depending on the choice of the transducer, the 10 k present is set so that a maximum of 5 Volt goes to the input of both operational amplifiers. The preset negative reference (10K) is adjusted below which motor is considered to be under loaded. Similarly preset positive reference (10K) is also adjusted at the input voltage level above which motor is considered to be over loaded. The circuit is wired such that the result from the reference negative amplifier C1 is logical 1 at the output (SU in Figure 3) thereof if the motor (not shown) load drops below the lower limit. Similarly, the output SD from the positive operational amplifier C2 is a logical 1 if the load goes over the designated upper limit. Only one of SU and SD can
be logical one at any given point of time. It must be noted that if the motor of the process machine is functioning within the designated upper and lower limits, both SU and SD will be logically 0.
Figure 5 provides the circuitry of the pulsar section of the device of the invention. The circuit depicted therein is of any one of PI or P2. The other part is identical thereto in terms of construction. The pulsers component generates square pulses to be used for counting by the counters. These square pulses are generated immediately on receipt of the signal from the comparator unit described in figure 4. Thus, if either of output SU or SD are input into pulse generation means P1 and P2 respectively, the pulser which is activated immediately generates square pulses and outputs them. When the output from comparator CI is the logical 1, the pulser PI generates a square pulse and outputs it through a communication means PU. Similarly, when the output SD from comparator C2 is the logical 1, the dedicated pulser thereof, namely P2 generates a square pulse and outputs it through communication means PD. Thus the output to the limit monitors which are designated as L1 and L2 in figure 3 PU or PD respectively.
The limit monitors L1 and L2 in figure 3 are connected in such a manner that a situation in cyclic counters, where the next number to maximum possible count is zero and similarly previous number to zero is maximum number, is avoided. The circuit of monitor LI and L2 are shown in figures 6 and 7 respectively. The L1 is the maximum limit monitor while L2 is the minimum limit momtor. Each monitor has a dedicated data bus. In the case of maximum limit monitor, the data bus is connected to two chip sets which can be standard chipsets. In the case of the minimum limit monitor L2, the data bus is connected to one chipset. The maximum limit monitor L1 ceases to forward pulses to the counter (PC in Figure 3) when all the logical 1 values at all bits of its Data Bus are detected. Similarly, the minimum limit monitor ceases to forward pulses received from the pulser unit P2 to the counter PC when all the bits of Data Bus becomes logical 0 in order to avoid cyclic action.
The power supply depicted in figure 8 is exemplary and not binding. The power supply can comprise any readily available power supply for +15V, +12V, +5V and -15V. In the alternate, the power supply can be manufactured out of 72XX series. However, it is important to note that the power source for the device of the invention does not exceed 100mA.
The pulse counter (PC in figure 3) itself is described in Figure 9. The counter used in the device of the invention is a readily available 8 bit ripple counter consisting of two 4
bit counter ICs (74193) and is able to count from 0 to 255. This enhances the accuracy of the system to up to 256 divisions of the 10 V signal i.e. least count of about 0.04 V.
The digital to analog converter depicted in figure 10 is provided with a single chip block with 8 bit D/A conversion means (IC DAC0808). It is important to note that one prerequiste has to be maintained, namely that in the IC, the value of the resistance at the pin 14 wherein the control voltage is input, should be equal to the preset value of 10k at pin 4 of the same chipset where the control voltage is output to the process machine.
The advantages of the present invention are that it provides a novel solution to control/minimise damage to process machines by regulating not the power innput but the load of the machine. The device uses components which are readily available commercially and therefore is inexpensive. However, savings in terms of time during the manufacturing process is significant since the apparatus ensures slow down of the load in the machine depending on the power position at the motor. Advantages of the invention
1. Dynamic Load Regulation of Process machines, on the basis of actual electrical load and/or speed demand of the machine.
2. Controlling the load to optimize the speed and hence the efficiency.
3. Speed controlling of Process machine on the basis of current load dynamically

We claim:
1. Dynamic load regulating device for process machines, said device comprising a
comparator means to identify any variation in load requirement of the process
machine, the comparator means comprising a first amplification means and a
second amplification means, the first amplification means generating a signal only
when determination of less load is indicated in the process machine and the second
amplification means generating a signal only when determination of overload is
indicated in the process machine and whereby the first and the second
amplification means form a open loop such that only one of them is operational at
any given point of time; a pulsar means comprising a first pulse generation means
connected to the first amplification means of the comparator means, and a second
pulse generation means connected to the second amplification means of the
comparator means, the first pulse generation means and the second pulse
generation means transmitting signals received from the first amplification means
and the second amplification means respectively in the form of a square pulse; a
load limit monitoring means comprising a maximum limit monitoring means and a
minimum limit monitoring means, wherein the maximum limit monitoring means
is connected to the first pulse generation means to receive a pulse therefrom on
activation of the first amplification means, and the minimum limit monitoring
means is connected to the second pulse generation means to receive a pulse
therefrom on activation of the second amplification means; the maximum and
minimum limit monitoring means both being independently connected to a pulse
counting means such that only one of the maximum limit monitoring means and
the minimum limit monitoring means transmits pulses to the pulse counting means
at any given point of time, and independently to an analog to digital converter to
receive signals therefrom depending on the input control voltage received by the
analog to digital converter from the process machine; the pulse counting means in
turn being connected independently to the analog to digital counter to transmit
thereto the pulses received from any one of the maximum or minimum limit
monitors.
2. A device as claimed in claim 1 wherein the first and second amplification means
are connected to a transducer through four diodes and a capacitor in order to
provide the first and second amplification means with a preset negative reference
value and a preset positive reference value respectively.
4. A device as claimed in claim 1 wherein the maximum and minimum limit monitors are operatively associated such that where the next number to maximum possible count is zero and similarly previous number to zero is maximum number is avoided.
5. A device as claimed in claim 1 wherein each of maximum and minimum limit monitor is provided with a data bus, the data bus of the the maximum limit monitor being connected to two chipsets, and the data bus of the minimum limit monitor being connected to one chipset.
6. A device as claimed in claim 1 wherein the power supply is a conventional power supply selected for +15V, +12V, +5V and -15V.
7. A device as claimed in claim 1 wherein the pulse counter is a conventional 8 bit ripple counter comprising of two 4 bit counter ICs and able to count from 0 to 255.
8. A device as claimed in claim 1 wherein the digital to analog converter is provided with a single chip block with 8 bit D/A conversion means and wherein the value of the resistance at the pin thereof where the control voltage is input is equal to the preset value of 10k at the pin of the chipset where the control voltage is output to the process machine.