Linear soft start control method and system with external control negative feedback regulation function

Abstract

The application provides a linear soft start control method and system with external control negative feedback adjustment function, which is realized by an external controller of a soft start device, and the comparison amount of a feedback signal is an output end signal of a soft start object; through a set control method, the soft start and soft-off process is more linear and timely, and an actual output slope is consistent with a set slope. The control method comprises the following: a soft start stage: the external controller performs soft start according to a set start slope, through introduction of negative feedback control, the load in the start process is realized to be linear output, and the slope of the set start slope and the soft start time are the same; a stable operation stage: the external controller controls the output to be stable through negative feedback mode according to a set output value; and a soft-off stage: the external controller performs soft-off according to a set off slope, through introduction of negative feedback control, the load output in the off process is realized to be linear, and the slope of the set off slope and the soft-off time are the same.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soft start control, in particular to a linear soft start control method and system with external control negative feedback regulation function. BACKGROUND

[0002] In the field of power electronics and automatic control, soft start function is often needed, and the most common soft start control method is linear soft start and linear soft off function. Due to the influence of load characteristics and control accuracy, the actual output during the soft start process is not linear, but there is a certain deviation. The internal control of the general soft start device does not have the feedback control function of the load signal. The algorithm of the internal controller can have predictive feedback function, for example, the predictive feedback control method based on the asynchronous motor soft starter disclosed in Chinese patent CN108134541A is such an internal controller algorithm, but this control algorithm is complex and cannot achieve real feedback control function of the load end output signal, and cannot truly realize linear accurate output of the device. SUMMARY

[0003] In order to solve the technical problems in the background art, the present application provides a linear soft start control method and system with external control negative feedback regulation function, which is realized by the external controller of the soft start device, the comparison quantity of the feedback signal is the output end signal of the soft start object, and the soft start and soft off process is more linear and on time through the set control method, and the actual output slope is consistent with the set slope.

[0004] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0005] A linear soft start control method with external control negative feedback regulation function, the control method is realized by the external controller of the soft start device, the comparison quantity of the feedback signal is the output end signal of the soft start object, and the control method comprises the following:

[0006] 1) Soft start stage: the external controller performs soft start according to the set start slope, and realizes linear output of the load in the start process through the introduction of negative feedback control, which is the same as the slope and soft start time of the set start slope, and the negative feedback control method in the soft start stage is as follows:

[0007] The control program of the external controller is executed once in a fixed time period, before the start of soft start, the system sets the given value i0 and the soft start time t s of stable operation, at the start of soft start, the output of the external controller is set to zero, and the remaining soft start program execution cycle number x1 is calculated according to the soft start time t s and the length of each program execution cycle t z .

[0008] x1 = t s / t z

[0009] Each soft start program execution cycle, the external controller compares the feedback signal i a and the given value i0 of stable operation, the actual value and the given value of the deviation i b , and calculates the remaining soft start increment i x , the external controller outputs the amount i q in this soft start program cycle x , the remaining soft start program execution cycle x1 value is reduced by 1 after the calculation is completed;

[0010] i b = i0-i a

[0011] i x = i b / x1

[0012] When the feedback comparison i a ≥ stable operation given value i0 or the remaining soft start program execution cycle number x1 = 0, the soft start stage is over; through this control method, effectively eliminate various interference factors, get the same given slope consistent soft start output ramp.

[0013] 2) stable operation stage: the external controller according to the set output value, through the negative feedback mode control output stable, stable operation stage negative feedback control method as follows:

[0014] The control program of external controller is executed once in fixed time period; the system sets the feedback signal comparison i a and the given value i0 of stable operation, the static error range i w and the deviation adjustment time t j ; according to the deviation adjustment time t j and the length of each program execution cycle t z , the deviation adjustment program execution cycle number x2 is calculated:

[0015] x2 = t j / t z

[0016] Each program execution cycle, the external controller compares the feedback i a and the given value i0 of stable operation, when i a and i0 difference i c is greater than i wWhen this happens, the external controller automatically starts the deviation adjustment program, using negative feedback to adjust the deviation.

[0017] i c =i a -i0

[0018] Within each adjustment program execution cycle, the adjustment amount i of the deviation adjustment program t for:

[0019] i t =i c / x2

[0020] when i c >i w At that time, and the external controller output quantity i q When >0, the external controller output quantity i q Reduce i t until i c Less than or equal to i w The timing adjustment program has finished executing; when i c <-i w At that time, and the external controller output quantity i q When the output is less than the maximum output limit, the external controller output i q Add |i t |, until|i c | Less than or equal to i w The deviation adjustment procedure has ended.

[0021] 3) Soft-shutdown phase: The external controller performs soft-shutdown according to the set shutdown ramp. By introducing negative feedback control, the load output during the shutdown process is made linear, with the same slope and soft-shutdown time as the set shutdown ramp. The negative feedback control method for the soft-shutdown phase is as follows:

[0022] The control program of the external controller is executed once at a fixed time period; at the start of soft shutdown, the external controller executes the program according to the soft shutdown time t. g and the execution cycle duration t of each program z Calculate the remaining number of program execution cycles x 3:

[0023] x3=t g / t z

[0024] In each program cycle, the external controller compares the feedback signal i. a Compare with 0 to obtain the difference i between 0 and 0. c And calculate the reduction amount i of the soft shutdown for each remaining program cycle. x External controller output i q Reduce i xAfter the calculation is completed, subtract 1 from the value of x3.

[0025] I c =i a -0

[0026] I x =i b / x3

[0027] When the feedback comparison quantity i a When the value is ≤0 or the number of remaining program execution cycles x3=0, the soft shutdown ends. This control method effectively eliminates various interference factors and obtains a soft shutdown output ramp that is consistent with the given slope.

[0028] The system of the linear soft-start control method with external control negative feedback adjustment function includes a soft-start device, an external controller, and a soft-start object. The external controller is a controller with negative feedback function, which integrates the functions of a ramp generator, comparator, and controller. The external controller outputs a control signal to the soft-start device, which drives the soft-start object. At the same time, the output signal of the soft-start object is input to the external controller as a controlled variable through a feedback loop, serving as a comparison quantity for the negative feedback function of the external controller. The linear soft-start control method with external control negative feedback adjustment function is implemented within the external controller.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] This invention provides a linear soft-start control method with external control negative feedback adjustment function, which is implemented by an external controller of the soft-start device. The comparison quantity of the feedback signal is the output signal of the soft-start object. The control method is different from the conventional control method. By setting the control method, the soft-start and soft-stop processes are made more linear and timely, and the actual output ramp is consistent with the set ramp. Attached Figure Description

[0031] Figure 1 This is a system structure diagram of an embodiment of the present invention;

[0032] Figure 2 The actual output curve of the embodiment of the invention is shown in the screenshot. Figure 1 ;

[0033] Figure 3 The actual output curve of the embodiment of the invention is shown in the screenshot. Figure 2 . Detailed Implementation

[0034] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0035] The application discloses a linear soft start control method with external control negative feedback regulation function, and the control method is realized by an external controller of a soft start device, and a comparison quantity of a feedback signal is an output end signal of a soft start object.

[0036] The control method comprises the following steps.

[0037] 1) soft start stage: the external controller performs soft start according to a set start ramp, and realizes linear output of a load in a start process by introducing negative feedback control, and the start process is identical to a slope of the set start ramp and a soft start time, and the negative feedback control method in the soft start stage is as follows.

[0038] A control program of the external controller is executed once in a fixed time period, before soft start, the system sets a given value i0 of stable operation and a soft start time t s , when the soft start starts, an output of the external controller is set to zero, and a remaining soft start program execution cycle quantity x1 is calculated according to the soft start time t s and a length t z of each program execution cycle.

[0039] x1=t s / t z

[0040] In each soft start program execution cycle, the external controller compares a comparison quantity i a of a feedback signal with the given value i0 of stable operation, obtains a deviation i b between an actual value and the given value, and calculates a soft start increment i x of each remaining soft start program cycle, and the external controller increases the output quantity i q of the external controller by the increment i x , and the remaining soft start program execution cycle quantity x1 is reduced by 1 after the calculation is completed.

[0041] i b =i0-i a

[0042] i x =i b / x1

[0043] When the comparison quantity i a of the feedback is greater than or equal to the given value i0 of stable operation or the remaining soft start program execution cycle quantity x1 is 0, the soft start stage ends, and by the control method, various interference factors are effectively eliminated, and a soft start output ramp identical to a given slope is obtained.

[0044] 2) stable operation stage: the external controller controls output stability by a negative feedback mode according to a set output value, and the negative feedback control method in the stable operation stage is as follows.

[0045] The control program of the external controller is executed once in a fixed time period; the system sets a comparison value i of the feedback signal a and the static error range i of the given value i0 of stable operation w and the deviation adjustment time t j ; according to the deviation adjustment time t j and the length t of each program execution period z , the number x2 of deviation adjustment program execution periods is calculated:

[0046] x2 = t j / t z

[0047] In each program execution period, the external controller compares the comparison value i of the feedback a and the given value i0 of stable operation, and when the difference i a between i c and i0 is greater than i w , the external controller automatically starts the deviation adjustment program and adjusts the deviation in a negative feedback manner.

[0048] i c = i a -i0

[0049] In each adjustment program execution period, the adjustment value i t of the deviation adjustment program is:

[0050] i t = i c / x2

[0051] When i c > i w , and the output value i q of the external controller is greater than 0, the output value i q of the external controller is reduced by i t , and the adjustment program execution ends when i c is less than or equal to i w ; when i c <-i w , and the output value i q of the external controller is less than the maximum output limit, the output value i q of the external controller is increased by |i t |, and the deviation adjustment program execution ends when |i c | is less than or equal to i w .

[0052] 3) Soft-off stage: the external controller performs soft-off according to the set-off slope, and through the introduction of negative feedback control, the load output in the off process is linear, which is the same as the slope of the set-off slope and the soft-off time; the negative feedback control method in the soft-off stage is as follows:

[0053] The control program of the external controller is executed once in a fixed time period; at the beginning of soft-off, the external controller calculates the number of remaining program execution periods x3 according to the soft-off time t g and the length of each program execution period t z .

[0054] x3=t g / t z

[0055] The external controller compares the comparison quantity i a of the feedback signal with 0, obtains the difference i c from 0, and calculates the reduction i x of soft-off in the remaining each program execution period, the output i q of the external controller is reduced by i x , and after the calculation is completed, the value of x3 is reduced by 1.

[0056] I c =i a -0

[0057] I x =i b / x3

[0058] When the comparison quantity i a of the feedback is less than or equal to 0 or the number of remaining program execution periods x3 is 0, the soft-off is ended; through the control method, various interference factors are effectively eliminated, and the soft-off output slope consistent with the given slope is obtained.

[0059] A conventional negative feedback control system is composed of a given, a comparator, a controller, an actuator, a controlled object, and a feedback link. The control system of the linear soft-start control method with external control negative feedback regulation function is composed of a controller with external control negative feedback function (hereinafter referred to as a controller), an actuator (a soft-starter), a controlled object, and a feedback link, and the system block diagram is shown in Figure 1 . The controller with external control negative feedback function integrates the functions of the slope generator (in the figure, 0-t1 is the slope rising time, i.e., the start stage, t1-t2 is the stable running time, and t2-t3 is the slope descending time, i.e., the soft-off time), the comparator, and the controller, and the control method is different from the conventional control method, and the operation is as described above. Specific embodiment one

[0061] Taking the silicon controlled rectifier power supply used in chrome plating of rolls as an example, 380V three-phase alternating current power is reduced in voltage by a rectifier transformer, and 12-phase low-voltage alternating current with an output voltage of 25V is output, rectified by 12 silicon controlled rectifiers, and then converted into direct current by a reactor and a capacitor filter, and the size of the output direct current is controlled by adjusting the triggering pulse conduction angle of the silicon controlled rectifiers.

[0062] The control system is composed of a controller with an external control negative feedback function (hereinafter referred to as a controller), an adjusting board, a triggering pulse board, silicon controlled rectifiers and an output current transmitter. The controller with an external control negative feedback function integrates a slope generator, a comparator and a controller into one body, and its output signal is a 0-10V voltage signal corresponding to an output current of 0-15000A. The 0-10V voltage signal is input to the adjusting board as an input signal. The adjusting board controls the silicon controlled rectifier triggering pulse board, which is used to control the conduction angle of the silicon controlled rectifiers, so as to control the output current of the power supply. A direct current transmitter is installed on the direct current bus at the output end of the silicon controlled rectifiers, which transmits the output current of 0-15000A into a 0-10V voltage signal, which is input to the controller for feedback, so as to realize closed-loop control.

[0063] The control process of the controller with an external control negative feedback function includes:

[0064] 1) Soft start stage:

[0065] The control program of the controller is executed once every t z =0.1S. For example, the system is set to have a stable running current i0 of 8000A before starting through a human-machine interface HMI, and the controller output voltage is 5.33V, and the soft start time t s is 60s. When the soft start starts, the controller output is set to 0V, and the soft start program execution cycle total number x1 is calculated according to the soft start time t s and the interval time t z of each program execution cycle:

[0066] x1=t s / t z =60 / 0.1=600 times

[0067] In the first soft start program cycle, the controller compares the feedback comparison quantity i a =0A with the given value i0=8000A of stable running, obtains the difference i b between the actual value and the given quantity, and calculates the soft start increment i x of each soft start program cycle, which is calculated as follows:

[0068] I b =i0-i a= 8000 - 0 = 8000 A

[0069] I x = i b / x1 = 8000 / 600 = 13.33 A

[0070] The controller outputs i q in this soft start program cycle x , that is: q I x = 0 + 13.33 = 13.33 A, corresponding to the controller output voltage of 0.0089 V. At the same time, the number of remaining soft start program execution cycles x1 is reduced by 1, that is:

[0071] x1 = 600 - 1 = 599 times.

[0072] In the second execution cycle of the soft start program, assuming the feedback voltage signal is 0.0133 V, corresponding to the current comparison quantity i a is 20 A, the feedback current is compared with the given value i0 = 8000 A of stable operation, the difference i b between the actual value and the given quantity is obtained, and the soft start increment i x of each soft start program cycle is calculated, as follows:

[0073] I b = i0 - i a = 8000 - 20 = 7980 A

[0074] I x = i b / x1 = 7980 / 599 = 13.32 A

[0075] The controller outputs i q in this soft start program cycle x , that is:

[0076] I q = 13.33 + i x = 13.33 + 13.32 = 26.65 A

[0077] Corresponding to the controller output voltage of 0.0178 V. At the same time, the number of remaining soft start program execution cycles x1 is reduced by 1, that is:

[0078] x1 = 599 - 1 = 598 times

[0079] Therefore, we find that the output increment changes continuously under the action of negative feedback in each soft start program cycle, ensuring that the slope of the final output current remains unchanged. Repeat the above program execution process, when the feedback comparison quantity i aThe soft start ends when the given value i0 is greater than or equal to the stable operating value or when the remaining number of soft start program execution cycles x1 = 0. This control method can effectively eliminate various interference factors and obtain a soft start output ramp consistent with the given slope.

[0080] 2) Stable operation phase:

[0081] The controller's control program per ton z =Executed once every 0.1 seconds. For example, before system startup, the comparison value i for system setting feedback is set via the Human-Machine Interface (HMI). a The static error range i of the given value i0 for stable operation w =2A, deviation adjustment time t j =2s. Adjustment time t based on deviation. j and the execution cycle duration t of each program z The number of execution cycles of the deviation adjustment program is calculated to be x2:

[0082] x2=t j / t z =2 / 0.1=20 times

[0083] During each program execution cycle, the controller compares the feedback quantity i. a Compare with a given value i0 that is running stably, when the difference between ia and i0 is i c When the deviation is greater than iw, the controller automatically starts the deviation adjustment program, using negative feedback to adjust the deviation. Assume that within the current program execution cycle, i... a =7800A, i0=8000A, then:

[0084] I c =i a -i0 = 7800 - 8000 = -200A

[0085] Because of I c <-i w , and i q <15000A, therefore, within the current program execution cycle, i q Increase i t The adjustment amount is:

[0086] i t =i c / x2=-200 / 20=-10A

[0087] During the program execution cycle, the controller will output i. q Add |i t |, that is, output i q An increase of 10A corresponds to an increase of 0.0067V in the controller output voltage.

[0088] The next program execution cycle, repeat the above process until |i c | is less than or equal to i w . Through the negative feedback control, ensure the output current constant.

[0089] 3) soft off stage:

[0090] The control program of the controller is executed once every t z = 0.1s. For example, before the system starts, the soft off time t g is set to 40s through the human-machine interface HMI. When the soft off starts, the controller calculates the number of remaining program execution cycles x3 according to the soft off time t g and the length of each program execution cycle t z :

[0091] x3 = t g / t z = 40 / 0.1 = 400 times

[0092] In the first soft off program cycle, the controller compares the feedback comparison quantity i a and 0A, assuming i a = 8000A, gets the difference between the actual value and 0A i c , and calculates the output reduction i x of each remaining soft off program cycle, while the number of remaining program execution times is reduced by 1, the specific calculation is as follows:

[0093] I c = i a - 0 = 8000-0 = 8000A

[0094] I x = i C / x3 = 8000 / 400 = 20A

[0095] The output quantity i q of the controller in this soft off program cycle is less than i x , that is:

[0096] I q = 8000-i x = 8000-20 = 7980A

[0097] The corresponding output voltage of the controller is 5.32V. At the same time, the number of remaining soft off program execution cycles x3 is reduced by 1, that is:

[0098] x3 = 400-1 = 399 times

[0099] In the second soft off program cycle, the controller compares the feedback comparison quantity i a and 0A, assuming i a=7950A, the difference i of the actual value 0A c And calculate the output reduction i of each remaining soft-off program cycle x The specific calculation is as follows:

[0100] I c = i a -0=7950-0=7950A

[0101] I x = i C / x3=7950 / 399=19.92A

[0102] The controller outputs the amount i q less i x That is:

[0103] I q =7950-i x =7980-19.92=7960.08A

[0104] The corresponding controller output voltage is 5.307V. At the same time, the number of remaining soft-on program execution cycles x3 is reduced by 1, that is:

[0105] x3=399-1=398 times

[0106] Therefore, we find that the output reduction amount in each soft-off program cycle changes continuously under the action of negative feedback, ensuring that the slope of the final output current remains unchanged. Repeat the above process when the feedback comparison amount i a ≤0 or the number of remaining program execution cycles x3=0, the soft-off ends. Through this control method, various interference factors can be effectively eliminated, and the soft-off output ramp consistent with the given slope is obtained.

[0107] From the embodiment figure of Figures 2-3 It can be seen that the linear soft-start control method with external control negative feedback regulation function of the application realizes more linear and on-time soft-start and soft-off process through the set control method, and the actual output ramp is consistent with the set ramp.

[0108] For those skilled in the art, improvements and modifications can be made to the application without departing from the principles of the application, and these improvements and modifications also fall within the protection scope of the claims of the application. The above is only the preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, and any skilled person in the art can make equivalent replacements or changes to the technical solutions and concepts of the application within the technical scope disclosed by the application.

Claims

1. A linear soft start control method with an external control negative feedback regulation function, characterized in that, The control method is realized by an external controller of the soft start device, a comparison quantity of the feedback signal is an output signal of the soft start object, and the control method comprises the following steps: 1) soft start stage: the external controller performs soft start according to a set start ramp, a load output in a start process is realized linearly by introducing negative feedback control, a slope of the set start ramp and a soft start time are same, and a soft start stage negative feedback control method is as follows: The control program of the external controller is executed once in a fixed time period, before the soft start, the system sets the given value i0 and the soft start time t in stable operation s ; at the beginning of the soft start, the output of the external controller is set to zero, and the number of remaining soft start program execution periods x1 is calculated according to the soft start time t s and the length of each program execution period t z . x1 = t s / t z Each soft start execution cycle, the external controller compares the feedback signal i a The actual value and the given value i b , and calculate the remaining soft start increment i x , the external controller outputs the value i q The increment i x , the remaining soft start execution cycle x1 value is reduced by 1 after calculation; i b = i0-i a i x = i b / x1 When the feedback comparison quantity i a ≥ the given value i0 of stable operation or the remaining soft start execution cycle number x1 = 0, the soft start phase ends; through the control method, various interference factors are effectively eliminated, and a soft start output ramp consistent with the given slope is obtained. 2) stable operation stage: the external controller controls output stability in a negative feedback mode according to a set output value, and a stable operation stage negative feedback control method is as follows: The control program of the external controller is executed once for a fixed time period; the system sets a comparison amount i of the feedback signal a and a static error range i of the given value i0 of the stable operation w and the deviation adjustment time t j ; according to the deviation adjustment time t j and the length t of each program execution period z , the number x2 of the deviation adjustment program execution periods is calculated x2 = t j / t z During each program execution cycle, the external controller compares the feedback comparison quantity i a with the given value i0of the stable operation, when i a is greater than i c , the external controller automatically starts the deviation adjustment program and adopts the negative feedback mode to adjust the deviation. w ​ i c = i a - i0 The adjustment amount i of the deviation adjustment program in each adjustment program execution cycle t is: i t = i c / x2 when i c >i w At that time, and the external controller output quantity i q When >0, the external controller output quantity i q Reduce i t until i c Less than or equal to i w The timing adjustment program has finished executing; when i c <-i w At that time, and the external controller output quantity i q When the output is less than the maximum output limit, the external controller output i q Add |i t |, until|i c | Less than or equal to i w The deviation adjustment procedure has ended. 3) soft-off stage: the external controller performs soft-off according to a set off ramp, a load output in an off process is realized linearly by introducing negative feedback control, a slope of the set off ramp and a soft-off time are same, and a soft-off stage negative feedback control method is as follows: The control program of the external controller is executed once for a fixed time period; at the start of soft-off, the external controller calculates the number of remaining program execution periods x3 according to the soft-off time t g and the length of each program execution period t z . x3 = t g / t z The external controller compares the feedback signal with 0 to get the difference i a and 0, and calculates the remaining soft-off reduction amount i c for each program cycle x The external controller outputs i q reduces i x and calculates the value of x3 minus 1 after completion I c = i a -0 I x = i b / x3 When the feedback comparison quantity i a ≤0 or the remaining program execution period quantity x3=0, the soft-off ends; through the control method, various interference factors are effectively eliminated, and the soft-off output ramp consistent with the given slope is obtained.

2. The system of linear soft start control method with external control negative feedback adjustment function according to claim 1, characterized in that, The soft start device, the external controller and the soft start object are included; the external controller is a controller with negative feedback function, all functions of a slope generator, a comparator and a controller are integrated, the external controller outputs a control signal to the soft start device, the soft start device drives the soft start object, meanwhile, an output signal of the soft start object is input to the external controller as a controlled quantity through a feedback link, as a comparison quantity of the negative feedback function of the external controller, and the external controller runs the linear soft start control method with the external control negative feedback regulation function.

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