Dual-loop segmented PID feedforward control charging method and system for electromagnetic emission energy storage device

Abstract

The present invention discloses a dual-loop segmented PID feedforward control charging method and system for an electromagnetic emission energy storage device, specifically: first obtain the current voltage setting value, obtain the charging voltage and charging current of the energy storage capacitor in real time, and calculate the voltage error; then calculate the current error according to the voltage error, and charge according to the current error calculation control amount; when the actual voltage reaches the voltage threshold, reduce the coefficient of the proportional controller of the voltage inner loop, enter the trickle charging, adopt feedforward estimation, take the steady-state control amount corresponding to the system when the charging reaches the target value as the estimated value, and constrain the final steady-state voltage; when the system detects that the capacitor voltage decays more than 2V, use trickle charging to supplement the voltage; after receiving the electromagnetic emission command, the system sends a control pulse to turn on the thyristor to complete the electromagnetic emission process. The present invention speeds up the charging speed of the electromagnetic emission energy storage device in the middle and late stages of charging, improves the charging efficiency, reduces overshoot, and improves the safety of charging.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics and control systems, in particular to a double-loop segmented PID feedforward control charging method for an electromagnetic emission energy storage device. Background Art

[0002] The charging process of the energy storage device of electromagnetic launch has a great influence on the performance of electromagnetic launch. The most important indicators of the charging process are the charging time of the energy storage capacitor and the voltage accuracy after charging.

[0003] Existing products and traditional high-voltage charging systems mostly use pure hardware or PLC control. Although the charging speed is fast, the hardware cost is high and the hardware circuit design is more complicated.

[0004] In some scenarios controlled by single-chip microcomputers, the charging methods of energy storage capacitors are mainly constant voltage charging, constant current charging, constant power charging, and constant voltage + constant current + trickle charging. The constant voltage charging method is slow in the later stage of charging; the constant current charging method controlled by single-loop PID is not fast in the early stage of charging, and due to the delay of the hardware mechanism, if the front-stage input is turned off when the voltage reaches the target value, the capacitor will still charge and overshoot in the process of reducing the current to 0. The input must be turned off in advance or the charging current must be reduced to reduce the overshoot; the constant power charging method controlled by single-loop PID will instantly generate a large current at the beginning of charging, which will damage the device.

[0005] Although the segmented charging method of constant voltage + constant current + trickle current is the current mainstream charging method, that is, constant voltage charging is used at the beginning and constant current charging is used later, the disadvantage of this method is that the current is uncontrollable in the initial stage of charging, and a large current will be generated instantly. In addition, in the actual experimental process, it is difficult to determine when to switch from constant voltage mode to constant current mode, and the timing of this conversion is even more difficult to unify depending on the target value. Summary of the invention

[0006] The purpose of the present invention is to provide a dual-loop segmented PID feedforward control charging method with small steady-state error, high charging efficiency and little damage to circuit components, thereby improving the problem that the initial current of an electromagnetic emission energy storage device is too large and uncontrollable.

[0007] The technical solution to achieve the purpose of the present invention is: a dual-loop segmented PID feedforward control charging method for an electromagnetic emission energy storage device, which adopts a voltage-current dual-loop PID, adds a proportional controller between the voltage error and the current to form a voltage outer loop, and the inner loop is a current loop, and adopts an incremental PI controller to form a dual-loop PI feedback control. The specific method is as follows:

[0008] Step 1: Use the AD sampling chip to read the value of the voltage adjustment knob to obtain the current voltage setting value;

[0009] Step 2: Obtain the values ​​of the voltmeter and the ammeter in real time to obtain the charging voltage and charging current of the energy storage capacitor, and calculate the voltage error in real time according to the voltage setting value of step 1;

[0010] Step 3, according to the voltage error obtained in step 2, the current error is calculated, the control amount of the system is calculated according to the current error, and the energy storage capacitor is charged according to the control amount of the system;

[0011] Step 4: When the actual voltage reaches the voltage threshold, the coefficient of the proportional controller of the voltage inner loop is reduced to enter trickle charging. Feedforward estimation is used to take the steady-state control amount corresponding to the system when the charging reaches the target value as the estimated value, and the steady-state control amount is used to constrain the final steady-state voltage.

[0012] Step 5: When the system detects that the voltage of the energy storage capacitor has decayed by more than 2V, the front-stage input is reopened, and the feedforward estimation value calculated in step 4 is used as the output of the control mechanism to perform PID control and use trickle charging to supplement the voltage;

[0013] Step 6: After receiving the electromagnetic launch command, the system sends a control pulse to turn on the thyristor, and the energy storage capacitor starts to release energy. At the same time, the voltage input of the system is disconnected, and the energy storage capacitor charges the inductor coil to complete the electromagnetic launch process.

[0014] Furthermore, the voltage setting value described in step 1 is transmitted to the control chip via IIC communication.

[0015] Furthermore, the values ​​of the voltmeter and the ammeter described in step 2 are obtained in real time using RS485 communication.

[0016] Furthermore, the calculation formula of the voltage error described in step 2 is:

[0017] e u (k) = U0-U c (1)

[0018] Where U0 represents the current voltage setting value, U c Indicates the current voltage value of the energy storage capacitor, e u (k) is the voltage error.

[0019] Furthermore, in step 3, the current error is calculated based on the voltage error obtained in step 2, the control amount of the system is calculated based on the current error, and the energy storage capacitor is charged based on the control amount of the system, as follows:

[0020] Step 3.1: The system enters the voltage outer loop and obtains the input value I of the current inner loop through the proportional controller.ref , the calculation formula is:

[0021] I ref =P×e u (k)(2)

[0022] Where P is the value of the proportional controller;

[0023] Step 3.2: Get the value of the ammeter in real time and calculate the current error e i (k), the calculation formula is:

[0024] e i (k) = I ref -I C (k)(3)

[0025] Among them I C (k) is the charging current of the energy storage capacitor obtained in real time by the ammeter;

[0026] Step 3.3, incremental PID control is a control algorithm that performs PID control by increasing the control amount, that is, the difference between the current control amount and the previous control amount. The algorithm formula is:

[0027] u(k)=u(k-1)+Δu(k) (4)

[0028] Among them, u(k) is the control amount of the control mechanism this time, u(k-1) is the control amount of the previous time, Δu(k) is the change of the control amount, and the calculation formula is:

[0029] Δu(k)=K P ×[e(k)-e(k-1)]+K i ×e(k)+K d ×[e(k)-2×e(k-1)+e(k-2)](5)

[0030] Among them, K P , K i , K d They represent the proportional, integral, and differential coefficients respectively. e(k) is the error between the current target value and the actual value, e(k-1) is the error value of the previous time, and e(k-2) is the error value between the previous target value and the actual value.

[0031] Setting Δe i (k) = e i (k)-e i (k-1), Δe u (k) = e u (k)-e u (k-1), ΔI C (k) = I C (k)-I C(k-1), substituting equations (2) and (3) into equation (5), we can obtain the control increment Δu(k) of the control system as:

[0032]

[0033] Step 3.4: Use the control increment of the system to charge the energy storage capacitor.

[0034] Furthermore, the step 4 is specifically as follows:

[0035] When the voltage is about to reach the voltage threshold U1, trickle charging is adopted, that is, P in formula (2) is reduced, so that the current decreases rapidly when it approaches the target value, thereby reducing the overshoot caused by hardware delay;

[0036] Set the voltage threshold U1 to 0.8 times the current voltage setting value U0, and use feedforward estimation to estimate the ideal energy storage capacitor voltage U c When the target voltage U0 is infinitely close and reaches a steady state, the control quantity u corresponding to the AC voltage regulation module is:

[0037]

[0038] In the formula, u max is the maximum value of the control amount, set to 100%, U m is the peak value of the AC voltage after the transformer is stepped up, plus the output of the incremental PID, the control quantity of the system at this time is:

[0039]

[0040] Furthermore, the step 5 is specifically as follows:

[0041] When the actual voltage U across the energy storage capacitor is detected c When it is equal to the target voltage U0, the previous stage input is turned off, and the voltage U0 is stored at both ends of the energy storage capacitor;

[0042] In a scenario where electromagnetic emission is not required immediately, the voltage stored in the energy storage capacitor gradually decays, so the voltage of the energy storage capacitor is detected in real time. When the attenuation of the detected voltage exceeds 2 volts, the feedforward estimation in step 3 is performed again, and trickle charging is used to supplement the voltage.

[0043] A dual-loop segmented PID feedforward control charging system for an electromagnetic emission energy storage device adopts a voltage-current dual-loop PID, adds a proportional controller between the voltage error and the current to form a voltage outer loop, and the inner loop is a current loop, and adopts an incremental PI controller to form a dual-loop PI feedback control. The system specifically includes an AD sampling chip, a voltage error calculation module, a control quantity calculation module, a voltage judgment module, a trickle charging module, and an energy storage capacitor charging module, which are used to implement the dual-loop segmented PID feedforward control charging method, wherein:

[0044] AD sampling chip, used to read the value of the voltage adjustment knob to obtain the current voltage setting value;

[0045] The voltage error calculation module is used to obtain the values ​​of the voltmeter and the ammeter in real time, obtain the charging voltage and charging current of the energy storage capacitor, and calculate the voltage error in real time according to the voltage setting value;

[0046] The control quantity calculation module calculates the current error according to the obtained voltage error, calculates the control quantity of the system according to the current error, and charges the energy storage capacitor according to the control quantity of the system;

[0047] The voltage judgment module reduces the coefficient of the proportional controller of the voltage inner loop when the actual voltage reaches the voltage threshold, enters trickle charging, adopts feedforward estimation, takes the steady-state control amount corresponding to the system when the charging reaches the target value as the estimated value, and uses this steady-state control amount to constrain the final steady-state voltage;

[0048] The trickle charging module, when the system detects that the voltage of the energy storage capacitor has decayed by more than 2V, reopens the front-stage input, uses the calculated feedforward estimate as the output of the control mechanism, performs PID control, and uses trickle charging to supplement the voltage;

[0049] After receiving the electromagnetic launch command, the energy storage capacitor charging module sends a control pulse to turn on the thyristor, and the energy storage capacitor starts to release energy. At the same time, the voltage input of the system is disconnected, and the energy storage capacitor charges the inductor coil to complete the electromagnetic launch process.

[0050] Compared with the prior art, the present invention has the following significant advantages: (1) by adopting incremental PID control, the charging current can be controlled in the initial stage of charging, and the speed in the later stage of charging is still controllable, thereby accelerating the charging speed in the middle and late stages of charging and improving the charging efficiency; (2) by adopting trickle charging when the voltage is about to reach the voltage threshold, the proportional control coefficient is reduced, so that the current decreases rapidly when approaching the target value, thereby reducing the overshoot caused by hardware delay and improving the safety of charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The present invention is a flow chart of a dual-loop segmented PID feedforward control charging method for an electromagnetic emission energy storage device.

[0052] Figure 2 It is a schematic diagram of the structure of the control system used for the electromagnetic emission energy storage device in the present invention.

[0053] Figure 3 It is a schematic diagram of the circuit structure of constant voltage charging adopted in the present invention.

[0054] Figure 4 It is a schematic diagram of the circuit structure of the dual-loop PI control charging adopted in the present invention.

[0055] Figure 5 It is a pulsating direct current curve diagram after the alternating current in the present invention is rectified after phase shifting and voltage regulation by bidirectional thyristor.

[0056] Figure 6 The schematic diagram of the circuit structure of the dual-loop PID control charging with feedforward control added in the present invention.

[0057] Figure 7 It is a comparison diagram of charging curves of a traditional charging method and a dual-loop segmented PID feedforward control charging method in an embodiment of the present invention. DETAILED DESCRIPTION

[0058] The dual-loop segmented PID feedforward control method proposed in the present invention solves the problems of slow charging speed in the late charging period, uncontrollable current in the early charging period, and large steady-state error in the traditional charging method.

[0059] Most traditional high-voltage charging control systems completely use pure hardware control or PLC as controllers. Although the real-time performance is better and the system responds quickly, the hardware cost is higher and the circuit design is complex. The disadvantages of using digital control are also obvious. Although a more complex algorithm can be implemented, the charging speed of the energy storage system used for the electromagnetic launch device is required to be very fast, and the signal processing and transmission will be delayed. The delay will cause the control mechanism to respond lag, resulting in untimely control and overshoot of the system. In order to make up for this shortcoming, the present invention proposes a dual-loop segmented PID feedforward control charging method for an electromagnetic launch energy storage device. The voltage and current dual-loop control is adopted in the charging process. By setting the proportional controller coefficient of the voltage outer loop, the initial value of the charging current tracked by the control system can be set. The larger the set current, the faster the energy storage capacitor charges in the early and middle stages of charging. Because the value is obtained by multiplying the voltage error by a proportional coefficient, the charging current value tracked by the system gradually decreases as the voltage error decreases. Therefore, the present invention can automatically slow down the charging speed when the energy storage capacitor approaches the target voltage value to reduce overshoot. Compared with the traditional constant voltage charging method, the initial charging speed is controllable, and there is no situation where the charging speed is too slow in the middle and late stages of charging and the voltage is not fully charged; compared with constant current charging, the initial charging speed is faster and the overshoot is smaller; compared with constant power charging, the initial charging current is controllable, the overshoot is smaller, and the safety is higher.

[0060] Combination Figure 1 , Figure 2 The present invention provides a dual-loop segmented PID feedforward control charging method for an electromagnetic emission energy storage device, comprising the following steps:

[0061] Step 1: Use the AD sampling chip to read the value of the voltage adjustment knob to obtain the current voltage setting value;

[0062] As a specific example, the voltage setting value is transmitted to the control chip via IIC communication to improve the accuracy and stability of data transmission.

[0063] Step 2: Obtain the values ​​of the voltmeter and the ammeter in real time to obtain the charging voltage and charging current of the energy storage capacitor, and calculate the voltage error in real time according to the voltage setting value of step 1;

[0064] As a specific example, the values ​​of the voltmeter and the ammeter are acquired in real time using RS485 communication.

[0065] As a specific example, the voltage error calculation formula is:

[0066] e u (k) = U0-U c (1)

[0067] Where U0 represents the current voltage setting value, U c Indicates the current voltage value of the charging capacitor, e u (k) is the voltage error.

[0068] Step 3, calculating the current error according to the voltage error obtained in step 2, calculating the control amount of the system according to the current error, and charging the capacitor according to the control amount of the system;

[0069] like Figure 3 The figure shows the traditional constant voltage charging method. The constant voltage charging formula is:

[0070]

[0071] In the formula, U is the capacitor voltage, E is the charging power supply, R is the resistance value in the circuit, and C is the capacitance value. From the constant voltage charging formula, it can be seen that the voltage U across the capacitor can only be infinitely close to the charging power supply E. Although the charging speed is fast in the early stage, the speed will be very slow and slower in the middle and late stages of charging. Obviously, the constant voltage method is too inefficient.

[0072] The constant current charging method is adopted, that is, the charging current of the capacitor is controlled by PID to be a constant value during the charging process. According to the characteristics of the capacitor, the voltage lags behind the current by one quarter of a cycle during the charging process of the capacitor. If the voltage error e is detected u When (k) is 0, the power supply is turned off, and the current will quickly decrease to 0. According to the capacitor charging formula

[0073]

[0074] It can be seen that the voltage across the capacitor will still be integrated in the process of the current being reduced to 0, and the current set during constant current charging must not be a small current. In the process of turning off the power supply to reduce it to 0, the result of the integral accumulation is not a number that can be ignored. As a result, the capacitor continues to charge, the voltage across the two ends exceeds the set value, and the system has an overshoot that cannot be ignored.

[0075] Therefore, the current mainstream charging method is a three-stage charging method of constant voltage + constant current + trickle current. Constant voltage is used in the initial charging stage to keep the output of the control mechanism at a constant value, and the charging speed is fast; constant current is used in the middle stage to maintain the charging speed of the capacitor; trickle charging is used in the final stage of charging, that is, charging with a small current until it is fully charged. Because it is a small current, when the power is turned off, the result of the integral accumulation in the process of the current being reduced to 0 is very small, so the overshoot can be reduced.

[0076] However, in actual applications, if the set voltage of the energy storage device needs to be adjusted frequently, the three-stage charging method will be more cumbersome, because according to the different set voltages, it is difficult to determine the segmented thresholds of the three-stage charging method of constant voltage + constant current + trickle current, that is, when to switch from constant voltage mode to constant current mode and when to switch from constant current mode to trickle current mode. Therefore, the present invention combines the first two stages into one, controls the voltage and current at the same time, and no longer controls in three stages. It adopts a voltage-current dual-loop PID, adds a proportional controller between the voltage error and the current, forms a voltage outer loop, and the inner loop is a current loop. It adopts an incremental PI controller to form a dual-loop PI feedback control, such as Figure 4 shown.

[0077] Figure 4 Where U0 is the voltage setting value, I ref is the input of the inner current loop. In the current loop, e i is the current error, in the voltage loop e u is the voltage error; u is the control quantity, which is used to control the control mechanism and represents the phase percentage of the bidirectional thyristor phase shift voltage regulation, 0<u<100%, and the control mechanism is the AC voltage regulation module composed of bidirectional thyristors; I C is the charging current of the capacitor, which can be obtained by the ammeter, U C is the actual voltage across the capacitor, which can be obtained by a voltmeter.

[0078] Step 3.1: The system enters the voltage outer loop and obtains the input value I of the current inner loop through the proportional controller. ref , the calculation formula is:

[0079] I ref =P×e u (k)(2)

[0080] Where P is the value of the proportional controller;

[0081] Step 3.2: Get the value of the ammeter in real time and calculate the current error e i (k), the calculation formula is:

[0082] e i (k) = I ref -I c (k)(3)

[0083] Among them I c (k) is the charging current of the capacitor obtained in real time by the ammeter;

[0084] Step 3.3, incremental PID control is a control algorithm that performs PID control by increasing the control amount, that is, the difference between the current control amount and the previous control amount. The algorithm formula is:

[0085] u(k)=u(k-1)+Δu(k) (4)

[0086] Among them, u(k) is the control amount of the control mechanism this time, u(k-1) is the control amount of the previous time, Δu(k) is the change of the control amount, and the calculation formula is:

[0087] Δu(k)=K p ×[e i (k)-e i (k-1)]+K i ×e i (k)+K d ×[e i (k)-2×e i (k-1)+e i (k-2)](5)

[0088] Among them, K P , K i , K d They represent the proportional, integral, and differential coefficients respectively. e(k) is the error between the current target value and the actual value, e(k-1) is the error between the previous target value and the actual value, and e(k-2) is the error between the previous target value and the actual value.

[0089] Setting Δe i (k) = e i (k)-e i (k-1), Δe u (k) = e u (k)-e u (k-1), ΔI C (k) = I C (k)-I C (k-1), substituting equations (2) and (3) into equation (5), we can obtain the control increment Δu(k) of the control system as:

[0090]

[0091] Step 3.4: Use the control increment of the system to control and charge the capacitor.

[0092] Step 4: When the actual voltage reaches the voltage threshold, the coefficient of the proportional controller of the voltage inner loop is reduced to enter trickle charging. Feedforward estimation is used to take the steady-state control amount corresponding to the system when the charging reaches the target value as the estimated value, and the control amount is used to constrain the final steady-state voltage.

[0093] Figure 5 (a) is the sinusoidal alternating current curve. Figure 5(b) is the pulsating DC curve after the AC power is rectified after phase shifting and voltage regulation by bidirectional thyristor. The AC power cycle is set to T, and the pulsating DC of half a cycle exists between t1 and T / 2, such as Figure 5 As shown in (b) in the figure, the sinusoidal alternating current U s for:

[0094] U s =U m sin(2πft)

[0095] Among them U m is the peak voltage and f is the frequency.

[0096] Figure 5 (b) shows a sinusoidal AC voltage that has been processed by phase shifting and voltage regulation. The final generated voltage is a pulsating DC voltage. The pulsating DC voltage has the characteristics of a positive half-cycle, but the negative half-cycle is cut off. If the pulsating DC is used to charge the capacitor, the final steady-state voltage of the capacitor will be close to the peak voltage of the positive half-cycle. Under ideal conditions, that is, without voltage loss and resistance, the capacitor is charged to the maximum value of the input voltage, which is the peak value of the pulsating DC. Therefore, when t1≤T / 4, the peak value of the pulsating DC voltage is always U m Even if the charging current is different and the time to fully charge is different, the final steady-state value of the voltage across the charging capacitor must be close to U m Therefore, the range of t1 is specified as (T / 4, T / 2). At this time, the control amount of the control mechanism is the control amount u of the control mechanism in step 3, that is, the phase shift voltage regulation percentage of the AC voltage regulation module:

[0097]

[0098] Where 0 <u<50%;

[0099] Set the target voltage value of the energy storage capacitor to U0. If the charging voltage waveform at both ends of the capacitor remains as follows Figure 5 As shown in (b), the peak voltage of the pulsating DC needs to be equal to U0, that is:

[0100] U0=U m sin(2πft1)

[0101] Since the range of t1 is (T / 4, T / 2), the symmetry of the sine function yields:

[0102]

[0103] so:

[0104]

[0105] Then the phase shift voltage regulation percentage u is equal to:

[0106]

[0107] The phase-shift voltage regulation percentage u is the theoretical control quantity when the capacitor is charged to U0 and reaches a steady state under ideal conditions. Although this control quantity is only an estimate under ideal conditions, it can be added to the control system as a feedforward control to constrain the final steady-state value, such as Figure 6 As shown:

[0108] Drawing on the idea of ​​compound control in control theory, the use of feedback and given input feedforward compound control can improve the tracking accuracy of the inner loop and enhance the steady-state performance without affecting the stability of the inner loop. In addition to the original feedback control, the given reference input U0 also controls the current I output by the current inner loop system through the feedforward device. C For such a composite control system, as long as the system parameters are properly selected, not only can the steady-state error be reduced or even eliminated, but the stability of the system is the same as that of the feedback control system when feedforward control does not exist.

[0109] When the voltage is about to reach the voltage threshold U1, trickle charging is adopted, that is, the proportional coefficient P in formula (2) is reduced, so that the current decreases rapidly when approaching the target value, thereby reducing the overshoot caused by hardware delay;

[0110] The voltage threshold U1 is set to 0.8 times the current voltage setting value U0, and the feedforward estimation is used. This estimate can estimate the ideal capacitor voltage U c The control quantity corresponding to the AC voltage regulation module when approaching the target voltage U0 and reaching a steady state is:

[0111]

[0112] In the formula, u max is the maximum value of the control amount, set to 100%, U m is the peak value of the AC voltage after the transformer is stepped up, plus the output of the incremental PID, the control quantity of the system at this time is:

[0113]

[0114] Step 5: When the system detects that the capacitor voltage decays by more than 2V, the front-stage input is reopened, and the feedforward estimate calculated in step 4 is used as the output of the control mechanism to perform PID control and use trickle charging to supplement the voltage, as follows:

[0115] When the voltage reaches the target value in step 3, the conventional charging control system will directly disconnect the voltage input of the previous stage to stop charging the energy storage capacitor. At this time, if the electromagnetic emission task is not completed, the voltage stored in the capacitor will continue to decay. c When it is equal to the target voltage U0, the front-stage input is turned off, and the voltage U0 is stored at both ends of the capacitor; in some special occasions, electromagnetic emission is not required immediately, so the voltage stored in the capacitor will slowly decay gradually. If the system does not replenish the voltage in time, it will affect the emission quality. Therefore, the system performs capacitor voltage detection in real time. When the attenuation of the detected voltage exceeds 2 volts, the feedforward estimation in step 3 is performed again, and the voltage is supplemented by trickle charging. Let the control mechanism output the estimated value in step 3. On the one hand, it completes a preliminary estimate, making the estimated value the initial value of the control amount, so that the system can respond quickly, otherwise the control amount needs to be accumulated from 0, which will increase the time to supplement the voltage. On the other hand, under the control of this estimated value, the voltage at both ends of the capacitor will not change suddenly, making the system more stable.

[0116] Step 6: After receiving the electromagnetic launch command, the system sends a control pulse to turn on the thyristor, and the capacitor starts to release energy. At the same time, the voltage input of the system is disconnected, and the capacitor charges the inductor coil to complete the electromagnetic launch process.

[0117] The present invention also provides a dual-loop segmented PID feedforward control charging system for an electromagnetic emission energy storage device, which adopts a voltage-current dual-loop PID, adds a proportional controller between the voltage error and the current to form a voltage outer loop, and the inner loop is a current loop, and adopts an incremental PI controller to form a dual-loop PI feedback control. The system specifically includes an AD sampling chip, a voltage error calculation module, a control amount calculation module, a voltage judgment module, a trickle charging module and an energy storage capacitor charging module, which are used to implement the dual-loop segmented PID feedforward control charging method, wherein:

[0118] AD sampling chip, used to read the value of the voltage adjustment knob to obtain the current voltage setting value;

[0119] The voltage error calculation module is used to obtain the values ​​of the voltmeter and the ammeter in real time, obtain the charging voltage and charging current of the energy storage capacitor, and calculate the voltage error in real time according to the voltage setting value;

[0120] The control quantity calculation module calculates the current error according to the obtained voltage error, calculates the control quantity of the system according to the current error, and charges the energy storage capacitor according to the control quantity of the system;

[0121] The voltage judgment module reduces the coefficient of the proportional controller of the voltage inner loop when the actual voltage reaches the voltage threshold, enters trickle charging, adopts feedforward estimation, takes the steady-state control amount corresponding to the system when the charging reaches the target value as the estimated value, and uses this steady-state control amount to constrain the final steady-state voltage;

[0122] The trickle charging module, when the system detects that the voltage of the energy storage capacitor has decayed by more than 2V, reopens the front-stage input, uses the calculated feedforward estimate as the output of the control mechanism, performs PID control, and uses trickle charging to supplement the voltage;

[0123] After receiving the electromagnetic launch command, the energy storage capacitor charging module sends a control pulse to turn on the thyristor, and the energy storage capacitor starts to release energy. At the same time, the voltage input of the system is disconnected, and the energy storage capacitor charges the inductor coil to complete the electromagnetic launch process.

[0124] Example

[0125] This embodiment uses an electromagnetic launch device and designs a control circuit board with a single-chip microcomputer as the core to control the electromagnetic launch device. The dual-loop segmented PID feedforward control charging method for the electromagnetic launch energy storage device proposed in the present invention is actually verified to verify its correctness and effectiveness.

[0126] In order to compare the charging effect of the dual-loop segmented PID feedforward estimation method proposed in the present invention with that of the traditional charging method, multiple methods were used for verification and comparison in the same electromagnetic transmitting device. Considering that the segmented charging method of constant voltage + constant current + trickle current is obviously better than the simple constant voltage charging or constant current charging method, only the segmented charging method of constant voltage + constant current + trickle current controlled by the single-loop PID algorithm and the constant power charging method were compared with the present invention.

[0127] The feedforward estimation method of the dual-loop segmented PID proposed in the present invention is used for verification. The specific process is: first, the voltage regulating knob is sampled by using the AD sampling chip, and the data is transmitted to the single-chip microcomputer through IIC communication; then charging begins, and the single-chip microcomputer uses RS485 communication to obtain the charging voltage and current in real time, and then uses the voltage and current dual-loop PID to control the charging current; when the voltage reaches the threshold U1, the voltage outer loop proportional coefficient is used, trickle charging is used, and feedforward estimation is introduced to reduce the steady-state error.

[0128] In the experiment, the charging capacitor of the electromagnetic launch device is 4000uf, and the transformer turns ratio is 1:4, that is, the input end of the rectifier bridge is a sinusoidal alternating current with an effective value of 880 volts and 50Hz, the current limiting resistor in the charging circuit is 100Ω, and the voltage target value U0 is set to 900 volts. In the method of the present invention, the proportional link of the voltage outer loop is set to 0.00027, the proportional link of the current inner loop is set to 100, and the integral link is set to 750. The voltage threshold U1 is set to 0.8×U0, and when trickle charging, the proportional link of the voltage outer loop is set to 0.0002. In the constant power charging method compared with the present invention, a single-loop PID control is used to keep the charging power at a constant value, that is, to keep the product of the charging current and the voltage at a constant value. In the constant voltage + constant current + trickle charging method compared with the present invention, the AC voltage regulation module outputs a fixed value to maintain constant voltage charging at the initial stage of charging, and then uses a single-loop PID to maintain constant current charging. When the charging is about to be completed, the set charging current is reduced to complete the trickle charging.

[0129] Table 1 Comparison of charging speed between the dual-loop segmented PID feedforward control charging method and the traditional charging method

[0130] method Feedforward Control Method of Dual-loop Sectional PID Constant power Constant voltage + constant current + trickle flow time 3.94s 5.98s 3.86s

[0131] Table 2 Comparison of charging voltage accuracy between the dual-loop segmented PID feedforward control charging method and the traditional charging method

[0132] method Feedforward Control Method of Dual-loop Sectional PID Constant power Constant voltage + constant current + trickle flow Steady-state error 1.2V 12.45V 7.95V

[0133] Tables 1 and 2 are comparison tables of charging time and steady-state error between the dual-loop segmented PID feedforward control method proposed by the present invention and the traditional charging method in the same electromagnetic launch device; Figure 7 The figure is a curve comparison diagram obtained by three charging methods. The constant power charging method controlled by a single loop PID in the figure is slow and has a very obvious steady-state error. In the experiment, although increasing the set power will increase the speed, the steady-state error will be larger; the segmented charging method of constant voltage + constant current + trickle current is faster, but still has a relatively obvious steady-state error, and the instantaneous current is too large at the initial charging stage, which is shown as a voltage curve that rises almost vertically in the figure; the charging voltage curve diagram of the dual-loop segmented PID feedforward control charging method proposed in the present invention is faster and has a smaller steady-state error than the constant power controlled by a single loop PID; the charging time is less than 0.1 second compared with the constant voltage + constant current + trickle current charging method, but the steady-state error is much smaller than the former, and the charging current can be changed by only changing the proportional link coefficient of the voltage loop, so the charging current is controllable and can protect the capacitor.

[0134] Depend on Figure 7It can be seen that the dual-loop segmented PID feedforward control charging method for the electromagnetic emission energy storage device proposed in the present invention has a 1.2% reduction in steady-state error compared with the single-loop PID controlled constant power charging method, and the charging time is 2.04 seconds faster; compared with the constant voltage + constant current + trickle charging method, the steady-state error is reduced by 0.75%. Although the charging time is 0.08 seconds slower, it is almost negligible, and the initial current rises smoothly, the instantaneous current is small, and the damage to the circuit components is small, which improves the problem of the current being too large and uncontrollable in the initial charging stage in the mainstream method, reduces the steady-state error, and maintains a faster charging speed.

[0135] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A dual-loop segmented PID feedforward control charging method for an electromagnetic emission energy storage device, characterized in that: Adopt voltage and current dual-loop PID, add a proportional controller between voltage error and current to form voltage outer loop, the inner loop is current loop, adopt incremental PI controller to form dual-loop PI feedback control, the specific method is as follows: Step 1: Use the AD sampling chip to read the value of the voltage adjustment knob to obtain the current voltage setting value; Step 2: Obtain the values ​​of the voltmeter and the ammeter in real time to obtain the charging voltage and charging current of the energy storage capacitor, and calculate the voltage error in real time according to the voltage setting value of step 1; Step 3, according to the voltage error obtained in step 2, the current error is calculated, the control amount of the system is calculated according to the current error, and the energy storage capacitor is charged according to the control amount of the system; Step 4: When the actual voltage reaches the voltage threshold, the coefficient of the proportional controller of the voltage inner loop is reduced to enter trickle charging. Feedforward estimation is used to take the steady-state control amount corresponding to the system when the charging reaches the target value as the estimated value, and the steady-state control amount is used to constrain the final steady-state voltage. Step 5: When the system detects that the voltage of the energy storage capacitor has decayed by more than 2V, the front-stage input is reopened, and the feedforward estimation value calculated in step 4 is used as the output of the control mechanism to perform PID control and use trickle charging to supplement the voltage; Step 6: After receiving the electromagnetic launch command, the system sends a control pulse to turn on the thyristor, and the energy storage capacitor starts to release energy. At the same time, the voltage input of the system is disconnected, and the energy storage capacitor charges the inductor coil to complete the electromagnetic launch process; According to the voltage error obtained in step 2, step 3 calculates the current error, calculates the control amount of the system according to the current error, and charges the energy storage capacitor according to the control amount of the system, as follows: Step 3.1: The system enters the voltage outer loop and obtains the input value I of the current inner loop through the proportional controller. ref , the calculation formula is: I ref =P×e u (k)(2) Where P is the value of the proportional controller, e u (k) is the voltage error; Step 3.2: Get the value of the ammeter in real time and calculate the current error e i (k), the calculation formula is: e i (k)=I ref -I C (k)(3) Among them I C (k) is the charging current of the energy storage capacitor obtained in real time by the ammeter; Step 3.3, incremental PID control is a control algorithm that performs PID control on the increment of the control quantity, that is, the difference between the current control quantity and the previous control quantity. The algorithm formula is: u(k)=u(k-1)+Δu(k)(4) Among them, u(k) is the control amount of the control mechanism this time, u(k-1) is the control amount of the previous time, Δu(k) is the change of the control amount, and the calculation formula is: Δu(k)=K P ×[e(k)-e(k-1)]+K i ×e(k)+K d ×[e(k)-2×e(k-1)+e(k-2)](5) Among them, K P , K i , K d They represent the proportional, integral, and differential coefficients respectively. e(k) is the error between the current target value and the actual value. e(k-1) is the error value of the previous time. e(k-2) is the error value between the previous target value and the actual value. Setting Δe i (k) = e i (k)-e i (k-1), Δe u (k) = e u (k)-e u (k-1), ΔI C (k) = I C (k)-I C (k-1), substituting equations (2) and (3) into equation (5), we can obtain the control increment Δu(k) of the control system as: Step 3.4, using the control increment of the system to control and charge the energy storage capacitor; The step 4 is specifically as follows: When the voltage is about to reach the voltage threshold U1, trickle charging is adopted, that is, P in formula (2) is reduced, so that the current decreases rapidly when it approaches the target value, thereby reducing the overshoot caused by hardware delay; Set the voltage threshold U1 to 0.8 times the current voltage setting value U0, and use feedforward estimation to estimate the ideal energy storage capacitor voltage U c When the target voltage U0 is infinitely close and reaches a steady state, the control quantity u corresponding to the AC voltage regulation module is: In the formula, u max is the maximum value of the control amount, set to 100%, U m is the peak value of the AC voltage after the transformer is stepped up, plus the output of the incremental PID, the control quantity of the system at this time is: 。 2. The dual-loop segmented PID feedforward control charging method for an electromagnetic emission energy storage device according to claim 1, characterized in that: The voltage setting value described in step 1 is transmitted to the control chip via IIC communication.

3. The dual-loop segmented PID feedforward control charging method for an electromagnetic emission energy storage device according to claim 1, characterized in that: The values ​​of the voltmeter and ammeter described in step 2 are obtained in real time using RS485 communication.

4. The dual-loop segmented PID feedforward control charging method for an electromagnetic emission energy storage device according to claim 1, characterized in that: The voltage error calculation formula described in step 2 is: e u (k)=U0-U c (1) Where U0 represents the current voltage setting value, U c Indicates the current voltage value of the energy storage capacitor.

5. The dual-loop segmented PID feedforward control charging method for an electromagnetic emission energy storage device according to claim 1, characterized in that: The step 5 is specifically as follows: When the actual voltage U across the energy storage capacitor is detected c When it is equal to the target voltage U0, the previous stage input is turned off, and the voltage U0 is stored at both ends of the energy storage capacitor; In a scenario where electromagnetic emission is not required immediately, the voltage stored in the energy storage capacitor gradually decays, so the voltage of the energy storage capacitor is detected in real time. When the attenuation of the detected voltage exceeds 2 volts, the feedforward estimation in step 3 is performed again, and trickle charging is used to supplement the voltage.

6. A dual-loop segmented PID feedforward control charging system for an electromagnetic emission energy storage device, characterized in that: A voltage-current dual-loop PID is adopted, a proportional controller is added between the voltage error and the current to form a voltage outer loop, and the inner loop is a current loop. An incremental PI controller is adopted to form a dual-loop PI feedback control. The system specifically includes an AD sampling chip, a voltage error calculation module, a control quantity calculation module, a voltage judgment module, a trickle charging module and an energy storage capacitor charging module, which are used to implement the dual-loop segmented PID feedforward control charging method according to any one of claims 1 to 5, wherein: AD sampling chip, used to read the value of the voltage adjustment knob to obtain the current voltage setting value; The voltage error calculation module is used to obtain the values ​​of the voltmeter and the ammeter in real time, obtain the charging voltage and charging current of the energy storage capacitor, and calculate the voltage error in real time according to the voltage setting value; The control quantity calculation module calculates the current error according to the obtained voltage error, calculates the control quantity of the system according to the current error, and charges the energy storage capacitor according to the control quantity of the system; The voltage judgment module reduces the coefficient of the proportional controller of the voltage inner loop when the actual voltage reaches the voltage threshold, enters trickle charging, adopts feedforward estimation, takes the steady-state control amount corresponding to the system when the charging reaches the target value as the estimated value, and uses this steady-state control amount to constrain the final steady-state voltage; The trickle charging module, when the system detects that the voltage of the energy storage capacitor has decayed by more than 2V, reopens the front-stage input, uses the calculated feedforward estimate as the output of the control mechanism, performs PID control, and uses trickle charging to supplement the voltage; After receiving the electromagnetic launch command, the energy storage capacitor charging module sends a control pulse to turn on the thyristor, and the energy storage capacitor starts to release energy. At the same time, the voltage input of the system is disconnected, and the energy storage capacitor charges the inductor coil to complete the electromagnetic launch process.

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