An algorithm and device for improving converter dynamic response based on power feedforward

Abstract

The present invention discloses an algorithm and device for improving the dynamic response of a converter based on power feedforward, the algorithm comprises the following steps: determining the output voltage error v of the converter o_error , and perform pre-regulation calculation of the regulator to obtain the regulator pre-output value v er_on ; Based on the output voltage V o , regulator pre-output value v er_on and the regulator expected value v in the first N cycles er_exp ‑N , calculate the power feedforward compensation value v er_short ; Set the regulator pre-output value v er_on and power feedforward compensation value v er_short Add together to get the regulator expected value v of the current cycle er_exp Based on the expected value calculation result of the regulator in the current cycle, the converter output voltage is adjusted. This solution significantly improves the converter's dynamic response characteristics without adding additional hardware circuits and control loops.

Description

Technical Field

[0001] The present invention relates to a converter, and in particular to an algorithm and a device for improving the dynamic response of a converter based on power feedforward. Background Art

[0002] Dynamic response rate is one of the key indicators for measuring power supply performance. The dynamic working conditions faced by users mainly include sudden changes in input voltage and output load. The use of input voltage feedforward control can effectively suppress input voltage disturbances. Currently, commonly used methods to improve the dynamic response rate of loads include: regulator design optimization, output current inner loop control, and connecting large capacitors in parallel at the load end.

[0003] The optimization of regulator design depends on the accurate modeling of the converter. However, for converters with complex structures, model establishment is very difficult. Even if the Bode diagram of the controlled object is obtained by frequency sweeping or other methods, the effect of optimizing the dynamics by optimizing the regulator design is limited due to the requirements of the converter stability margin. Especially under application conditions with wide input or wide output range, its dynamic optimization effect will be even more limited.

[0004] Adding a load current inner loop control can monitor the load current in real time, thereby effectively improving the load dynamic response rate. However, on the one hand, this solution requires the addition of an additional hardware current sampling circuit, which increases the complexity of the hardware circuit to a certain extent. On the other hand, the introduction of the current inner loop increases the complexity of the control loop.

[0005] Connecting a large capacitor in parallel at the output end can effectively reduce the fluctuation of the load voltage during the dynamic process without increasing the complexity of the control circuit. However, the connection of the large capacitor will greatly increase the volume and weight of the converter, seriously affecting the power density of the converter.

[0006] In summary, the fast load dynamic response solution in the prior art increases the complexity of the control loop or hardware circuit, and has limited optimization effect. Summary of the Invention

[0007] Purpose of the invention: The purpose of the present invention is to provide an algorithm and device for improving the dynamic response of the converter based on power feedforward. This solution can complete load dynamic compensation within one calculation cycle at the fastest without adding additional hardware circuits and control loops, and the optimization effect is significant.

[0008] Technical solution: The algorithm for improving the dynamic response of the converter based on power feedforward of the present invention includes the following steps:

[0009] S1: Determine the output voltage error v of the converter o_error , and perform pre-regulation calculation of the regulator to obtain the regulator pre-output value v er_on ;

[0010] S2: Based on the output voltage V o , regulator pre-output value v er_on and the regulator expected value v of the first N control calculation cycles er_exp -N , calculate the power feedforward compensation value v er_short ;

[0011] S3: Set the regulator pre-output value v er_on and power feedforward compensation value v er_short Add together to get the regulator expected value v of the current cycle er_exp ;

[0012] S4: Based on the calculation result of the regulator expected value of the current cycle, adjust the output voltage of the converter.

[0013] In step S1, the output voltage error v of the transformer is determined o_error , and perform pre-regulation calculation of the regulator to obtain the regulator pre-output value v er_on , specifically including the following: First, the input voltage V in and the output voltage V o ; Then the sampled output voltage V o With the preset output voltage V o Closed loop reference value V o_ref The output voltage error of the transformer is obtained by subtracting o_error ; Then according to the output voltage error v of the converter o_error , perform pre-regulation calculation of the regulator. The pre-regulation calculation of the regulator includes, first, performing regulator compensation calculation to obtain the regulator compensation output value v er , the regulator compensates the output value v er Perform limiting processing to obtain the regulator pre-output value v er_on ;

[0014] According to the algorithm for improving the dynamic response of the converter based on power feedforward, it is characterized in that in step S2, the power feedforward compensation value v er_short The expression is:

[0015]

[0016] Where C f Indicates the converter output filter capacitor; L m Represents the magnetizing inductance of the transformer in the converter; f s Indicates the switching frequency of the converter; f ctrlIndicates the converter control calculation frequency; N indicates the number of control calculation cycles between the control calculation cycle in which the variable value stored for calculating the power feedforward compensation value is located and the current control calculation cycle, and N is a positive integer greater than or equal to 1; V o Indicates the converter output voltage sampled in the current calculation cycle; V o -N Indicates the output voltage value during the first N calculation cycles; v er_exp -N Indicates the first N calculation cycles used to calculate the regulator output of T1.

[0017] In step S4, the output voltage of the converter is adjusted based on the calculation result of the regulator expected value of the current cycle, which specifically includes the following steps: in and the regulator expected value v er_exp , calculate the on-times T1 and T2 of the first switch tube Q1 and the second switch tube Q2; generate a PWM wave according to the on-times T1 and T2 of the first switch tube Q1 and the second switch tube Q2 to drive the first switch tube Q1 and the second switch tube Q2.

[0018] By adding a judgment condition before step S2, it is possible to judge whether the power feedforward compensation value v needs to be recalculated in different calculation cycles. er_short The judgment condition is to judge the voltage error v o_error Is it greater than the preset value v o_error_th ; If so, recalculate the power feedforward compensation value v er_short ; If not, directly calculate the regulator expected value v er_exp .

[0019] The present invention also includes a device for improving the dynamic response of a converter based on power feedforward, the device comprising: a subtractor module (200) for determining an output voltage error v o_error ; Converter pre-regulation module (201), for based on the output voltage error v o_error Perform loop compensation calculation and limit the calculation result to obtain the regulator pre-output value v er_on ; Power feedforward module, used to calculate the power feedforward compensation value v er_short ; The first adder module is used to calculate the regulator expected value v er_exp ; Output voltage adjustment module, for adjusting the output voltage of the converter based on the regulator expected value; wherein the subtractor module, the converter pre-regulation module, the first adder module, and the output voltage adjustment module are connected in sequence; the input signal of the first input terminal of the power feedforward module is the output voltage V oThe second input end is connected to the output end of the converter pre-regulation module, the third input end is connected to the output end of the first adder module, and the output end of the power feedforward module is connected to the input end of the first adder module.

[0020] The power feedforward module includes a first data storage module, a transient mutation power calculation module, an adder, a transient feedforward value calculation module, a second data storage module, and a pre-mutation power calculation module; the first data storage module, the transient mutation power calculation module, the adder, and the transient feedforward value calculation module are connected in sequence, the second data storage module is connected to the pre-mutation power calculation module, and the output end of the pre-mutation power calculation module is connected to the second adder.

[0021] The first data storage module is used to store the output voltage value V during the first N calculation cycles. o -N The transient power calculation module is based on the output voltage V sampled in the current cycle. o And the stored output voltage V of the first N cycles o -N Calculate the power P of transient mutation o_short :

[0022]

[0023] Where C f Represents the converter output filter capacitor; f ctrl Indicates the converter control frequency;

[0024] The second data storage module stores the regulator expected value v of the first N calculation cycles. er_exp -N ;

[0025] The power calculation module before the mutation is based on the regulator expected value v of the first N calculation cycles er_exp -N Calculate the output power P of the converter in the first N calculation cycles before the load mutation o_last :

[0026]

[0027] Among them, L m Indicates the magnetizing inductance value, f s represents the switching frequency of the converter;

[0028] The second adder converts the transient power P o_short and the output power P of the converter in the first N calculation cycles before the load mutation o_last Add up to get the total power P after the load mutation o_totalThe transient feedforward value calculation module is used to calculate the total power P after the load mutation o_total And the output value of the limiting device v er_on Calculate the power feedforward compensation value v er_short , which serves as the input signal of the first adder module.

[0029] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial effects: it can realize rapid and accurate compensation of the transient operating conditions of the converter, and can complete transient compensation in as fast as one calculation cycle. The technical solution of the present invention does not require the addition of additional hardware circuits and control loops, which makes the converter have the characteristics of high power density and simple control structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the process of the present invention;

[0031] Figure 2 Schematic diagram of the structure of the device for improving the dynamic response of a converter based on power feedforward according to the present invention;

[0032] Figure 3 The diagram of the active clamp flyback converter and its key current flow is shown in Figure 2.

[0033] Figure 4 This is a typical waveform diagram of the critical continuous mode of the active clamp flyback converter;

[0034] Figure 5 This is a schematic diagram of the algorithm derivation structure of the power feedforward module;

[0035] Figure 6 for Figure 5 Working flow chart of the power feedforward module;

[0036] Figure 7 The specific implementation process of the power feedforward control scheme;

[0037] Figure 8 It is a specific implementation process of a power feedforward control scheme with conditional judgment;

[0038] Figure 9 This is the dynamic experimental waveform of traditional proportional-integral control;

[0039] Figure 10 This is the dynamic experimental waveform using the power feedforward control algorithm. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is described in detail below in conjunction with specific implementation methods and the accompanying drawings.

[0041] like Figure 1As shown, the algorithm for improving the dynamic response of the converter based on power feedforward of the present invention includes the following steps:

[0042] S1: Determine the output voltage error v of the converter o_error , and perform pre-regulation calculation of the regulator to obtain the regulator pre-output value v er_on ; Specifically include the following contents:

[0043] S700: Sampling converter input voltage V in and the output voltage V o ;

[0044] S701: The sampled output voltage V o With the preset output voltage V o Closed loop reference value V o_ref The output voltage error v of the converter is obtained by subtracting o_error ;

[0045] S702: According to the output voltage error v of the converter o_error , perform pre-regulation calculation of the regulator and obtain the regulator pre-output value v er , the regulator pre-output value v er Perform the limiting process to get v er_on ; Among them, the regulator pre-output value v er The expression of is shown in formula (3);

[0046] S2: Based on the output voltage V o , regulator pre-output value v er_on and the regulator expected value v of the first N control calculation cycles er_exp -N , calculate the power feedforward compensation value v er_short ; Power feedforward compensation value v er_short The expression of is shown in formula (20); Step S2 corresponds to step S703;

[0047] S3: Set the regulator pre-output value v er_on and power feedforward compensation value v er_short Add together to get the regulator expected value v of the current cycle er_exp ; Step S3 corresponds to step S704;

[0048] S4: Based on the calculation result of the regulator expected value of the current cycle, adjust the output voltage of the converter, which specifically includes the following:

[0049] S705: According to the input voltage V in and the regulator expected value v er_exp , calculate the conduction time T1 and T2 of the first switch tube Q1 and the second switch tube Q2;

[0050] S706: Generate a PWM wave according to the on-times T1 and T2 of the first switch tube Q1 and the second switch tube Q2, so as to drive the first switch tube Q1 and the second switch tube Q2;

[0051] S707: The output voltage V sampled in this calculation cycle is o Stored in V o -1 Variable, used for calculating the power feedforward compensation value in the next cycle;

[0052] S708: Store the regulator expected value calculated in this cycle into v er_exp -1 Variable, used for calculating the power feedforward compensation value in the next cycle;

[0053] S709: Waiting for the next calculation cycle.

[0054] The present invention also includes a power feedforward-based boost converter dynamic response device, which is applicable to various types of power converters. In this embodiment, a digitally controlled active clamped flyback converter using a proportional-integral regulator is taken as an example to describe the present solution in detail. In particular, the fast load response algorithm described in the example of the present invention can also be implemented using an analog circuit; the fast load response algorithm described in the example of the present invention is also applicable to other regulators, such as PID regulators, multi-zero multi-pole regulators, etc.; the fast load response algorithm described in the example of the present invention is also applicable to other power topologies, such as four-switch buck-boost converters, boost converters, resonant converters, etc.

[0055] like Figure 3 As shown, the active clamp flyback circuit used in this embodiment consists of two parts: the primary side and the secondary side. The transformer T1 connects the primary and secondary sides to achieve energy transfer. The turns ratio of the transformer T1 is n:1. The primary side of the active clamp flyback circuit is composed of the input voltage source V in , the first switch tube Q1, the second switch tube Q2, the transformer excitation inductor L m , transformer leakage inductance L r , Clamping capacitor C r The first switch tube Q1 also includes its parasitic diode D1 and parasitic capacitor C1; the second switch tube Q2 is a clamp switch tube, and similarly, Q2 also includes its parasitic diode D2 and parasitic capacitor C2. The specific connection method is as follows: Input voltage source V in Connect the transformer leakage inductance L r One end, clamping capacitor C r One end, transformer leakage inductance L r The other end is connected to the transformer excitation inductor L m , transformer magnetizing inductance L mAfter being connected in parallel with the primary side of the transformer T1, the first switch tube Q1 and the second switch tube Q2 are connected respectively. The first switch tube Q1, the parasitic diode D1 and the parasitic capacitor C1 are connected in parallel. The second switch tube Q2, the parasitic diode D2 and the parasitic capacitor C2 are connected in parallel. The clamping capacitor C r The other end is connected to the second switch tube Q2.

[0056] The secondary side of the active clamp flyback circuit includes a rectifier diode D3, a capacitor C3, a third switch tube Q3, and an output filter capacitor C f and the load resistor R LD , load resistance R LD The voltage across the two ends is the output voltage, denoted as V o The specific connection method is as follows: the rectifier diode D3, capacitor C3, and the third switch tube Q3 are connected in parallel. The drain of the third switch tube Q3 is connected to one end of the secondary winding, and the other end of the secondary winding of the transformer is connected to the output filter capacitor C f , output filter capacitor C f and the load resistor R LD After being connected in parallel, they are connected to the third switch tube Q3.

[0057] like Figure 2 As shown, the device for improving the dynamic response of the converter based on power feedforward is a control structure of an active clamp flyback circuit, which is used to achieve an output voltage V o The device includes a subtractor module 200, a converter pre-regulation module, a regulator 201, a limiter 202, a first adder module 203, an output voltage adjustment module, and a power feedforward module 206, wherein the converter pre-regulation module is used to adjust the output voltage based on the output voltage error v o_error Perform loop compensation calculation and limit the calculation result to obtain the regulator pre-output value v er_on The converter pre-regulation module includes a regulator 201 and a limiter 202; the output voltage adjustment module is used to adjust the output voltage of the converter based on the regulator's expected value, and the output voltage adjustment module includes a T1-T2 calculation module 204 and a PWM generation module 205. The specific connection between each module is as follows: the subtractor module 200, the regulator 201, the limiter 202, the first adder module 203, the T1-T2 calculation module 204, and the PWM generation module 205 are connected in sequence; the input signal of the first input terminal of the power feedforward module 206 is the output voltage V o The second input end is connected to the output end of the limiting device 202, the third input end is connected to the output end of the first adder module 203, and the output end of the power feedforward module 206 is connected to the input end of the first adder module (203).

[0058] The input signal of the device for improving the dynamic response of the converter based on power feedforward is the real-time sampled output voltage V o And set the output voltage V o Closed loop reference value V o_ref The output signal of the device for improving the dynamic response of the converter based on power feedforward is G Q1 , G Q2 , respectively used to drive the first switch Q1 and the second switch Q2 in the active clamp flyback circuit.

[0059] The input signal of the subtractor 200 is the output voltage V o and the closed-loop reference value V o_ref , the output signal is the difference between the two input signals, denoted as v o_error , the output signal v of the subtractor 200 o_error The expression is:

[0060] v o_error =V o_ref -v o (1)

[0061] The regulator 201 is used to adjust and compensate the output error signal to achieve the voltage stabilization output function of the converter. The input signal of the regulator 201 is the output signal v of the subtractor 200. o_error In this embodiment, a digital control method is adopted, and the regulator 103 adopts a proportional integral regulator, and its S domain expression is:

[0062]

[0063] Among them, k p is the proportionality coefficient, k i is the integral coefficient. The output signal of the regulator 201 is recorded as v er , then the expression of its S domain is:

[0064]

[0065] The limit module 202 outputs v to the regulator 201 er In this embodiment, the digital control chip software is used to implement the limiting module 202. The input signal of the limiting module 202 is the output v of the regulator 201. er , the output signal is the limiting output result, recorded as v er_on , at the same time, v er_on It also represents the regulator pre-output value that is ultimately used to calculate the conduction time of Q1 in the current cycle. The following is the specific process of the limiter module in this embodiment to achieve the limit: limit v er The maximum value of v er_max , limited to v er The minimum value is ver_min , that is, when the regulator 201 outputs the result v er >v er_max When the limit output result is v er_on =v er_max ; When the regulator outputs the result v er <v er_min When the limit output result is v er_on =v er_min , when the regulator output value v er Between v er_min and v er_max When the limit output is between er_on =v er .

[0066] The input signal of the first adder 203 is the output result v of the limiting device 202. er_on The output of the power feed forward module 206 is er_short The output signal of the first adder 203 is the result of adding the input signals, denoted as v er_exp , the adder outputs the result v er_exp The final value used to calculate the conduction time of Q1 represents the regulator expected value used to calculate the conduction time of Q1 under the new load state. The first adder 203 outputs the result v er_exp The expression is:

[0067] v er_exp =v er_on +v er_short (4)

[0068] The input signal of the T1-T2 calculation module 204 is the output result v of the first adder 203. er_exp and the converter input voltage V in , T1 and T2 are the conduction time of the first switch tube Q1 and the second switch tube Q2. In this embodiment, the dead time is ignored, and it can be considered that the first switch tube Q1 and the second switch tube Q2 are complementary to each other. The calculation formulas of T1 and T2 are:

[0069]

[0070] T2=T s -T1 (6)

[0071] Where T s is the switching period of the converter.

[0072] The PWM generation module 205 generates PWM for driving the first switch Q1 and the second switch Q2 according to the result of the T1-T2 calculation module 204 .

[0073] The power feedforward module 206 is the key module of this solution. Its input signal is the sampled converted output voltage V o , the output result v of the limiting device 202 er_on and the output result v of the first adder 203 er_exp The output of the power feedforward module is the power feedforward compensation value, which is denoted as v er_short , which represents the current calculation cycle in the regulator output result v er_on On the basis of , a compensation value needs to be added to meet the power demand of the new load.

[0074] The theoretical basis and derivation process of the power feedforward algorithm proposed in the present invention will be described in detail below.

[0075] Sudden output load changes are a fundamental dynamic condition faced by power electronic converters. Users expect converters to exhibit excellent dynamic performance in all load transitions, with minimal output voltage fluctuations and a very fast recovery time to the closed-loop reference value. Fast load response requires that the input power quickly follow the load change. If the input power exceeds the load's required power, the output voltage will overcharge; if the input power is less than the load's required power, the output voltage will drop.

[0076] To explore the algorithm to achieve fast load response, we must first clarify the corresponding relationship between load power and related variables in the converter, and then combine Figure 3 Briefly describe the working principle of the active clamp flyback converter in this embodiment. In this embodiment, the active clamp flyback converter operates in critical continuous mode, and the transformer leakage inductance L r The current flowing through is denoted as i Lr , transformer magnetizing inductance L m The current flowing through is denoted as i Lm , leakage inductance current i Lr and the magnetizing inductor current i Lm The positive direction of Figure 3 As shown in Figure 2, a single working cycle of the converter can be divided into four working modes: t0~t1, t1~t2, t2~t3, and t3~t4. Figure 4 As shown. During the period t0 to t1, Q1 is turned on and the input voltage V in To excite transformer T1, the leakage inductance current i Lr and the magnetizing inductor current i Lm Equal and synchronous linear rise, at this stage, the original secondary side is disconnected, the load is connected to the output filter capacitor C f Support power supply. In the time period of t1~t2, the first switch tube Q1 is turned off, the second switch tube Q2 is turned on, the secondary rectifier diode D3 is turned on, the voltage across the transformer T1 is clamped by the output voltage, the excitation current decreases linearly, and the transformer leakage inductance Lr With the clamping capacitor C r Resonance, energy is transferred to the secondary side through the transformer. At time t2, the leakage inductance current i Lr and the magnetizing inductor current i Lm Equal, the primary and secondary sides of the transformer are disconnected. During the time period t2 to t3, the clamping capacitor C r Under the action of voltage, the inductor is demagnetized and the exciting inductor current i Lm and leakage inductance current i Lr Synchronous decrease. At time t3, the second switch tube Q2 is turned off. At this time, the excitation induction current drops to a negative value. This current simultaneously discharges the parasitic capacitance C1 of the first switch tube Q1 and charges the parasitic capacitance C2 of the second switch tube Q2 during the time period t3 to t4. Before time t4 arrives, the first parasitic capacitance C1 is completely discharged. The first parasitic diode D1 provides a freewheeling path, providing the first switch tube Q1 with the condition of zero voltage turn-on, thus entering the next switching cycle.

[0077] In this embodiment, the dead time is short, and it can be assumed that all the energy in the magnetizing inductor is transferred to the load end. From this, the expression for the output power can be obtained:

[0078]

[0079] Among them, P o is the output power, L m is the magnetizing inductance value, i max is the maximum value of the magnetizing inductor current, f s is the switching frequency of the converter. m The minimum value of the upper current can be approximated to zero, and the following equation is established based on the volt-second balance:

[0080]

[0081] Where T1 is the conduction time of the first switch Q1. Combining equations (7) to (8), it can be seen that when the circuit parameters are fixed, the converter input voltage is fixed, and the converter switching frequency f s When the first switch tube Q1 is fixed, the conduction time T1 and the output power P o There is a one-to-one correspondence, that is, when the load changes suddenly, as long as T1 can quickly follow the load change, the converter can have a good load response. It is worth noting that the output power P mentioned here is o It actually refers to the power that the input end can provide to the output end, rather than the power required by the output load.

[0082] To explore the factors that affect the rate of change of T1, if we temporarily ignore the effects of the power feedforward module 108 and the limiter 104, the following relationship holds:

[0083] v er_short =0 (9)

[0084] v er_on =v er (10)

[0085] Combining formula (4), we can get:

[0086] v er_exp =v er (11)

[0087] Combining equations (5) and (11), it can be seen that the speed of change of the conduction time T1 of the first switch tube Q1 directly depends on the speed of change of the regulator output. Similarly, combining equations (5), (7), (8), and (11), the output power P can be obtained. o With the regulator output v er The corresponding relationship:

[0088]

[0089] Since the embodiment of the present invention adopts a digitally controlled pi regulator, the regulator is discretized as shown below:

[0090] v er (k)=v er_integ (k)+k p ·e(k) (13)

[0091] Among them, v er (k) is the regulator output v in the current cycle er ;v er_integ (k) is the output value of the integration link in the current cycle; e(k) is the output signal v of the subtractor in the current cycle o_error ; Integral link output value v er_integ The expression of (k) is:

[0092] v er_integ (k)=v er_integ (k-1)+k i ·e(k) (14)

[0093] Among them, v er_integ (k-1) is the output value of the integral link in the previous calculation cycle. Combining equations (13) and (14), it can be seen that increasing the regulator output v er The rate of change can be increased by increasing the proportional coefficient k p and the integral coefficient k i However, this method of increasing the regulation rate will directly affect the stability of the converter and cause output oscillation. On the other hand, when the proportional coefficient k pOr integration coefficient k i If the value is too large, it may cause over-regulation. If the value is not large enough, it will take several calculation cycles to get the desired V. er , the effect of fast load response cannot be achieved.

[0094] The power feedforward scheme proposed in the technical solution of the present invention can not only achieve rapid compensation, but also provide accurate compensation values ​​without causing over-compensation or under-compensation, and is applicable to any regulator. As can be seen from formula (12), the required regulator output value can be calculated by simply knowing the output power value after the mutation, that is, the regulator output value expected under the current load state. Obviously, even if the regulator output v er The regulator expected value can be quickly obtained by superimposing an accurate compensation value on the regulator output value, and the regulator expected value is the output v of the first adder 205. er_exp , the regulator output value is limited to obtain v er_on The core function of the power feedforward module 208 is to calculate the power feedforward compensation value v er_short .

[0095] like Figure 5 and Figure 6 As shown, the power feedforward module 208 includes a first data storage module 500 , a transient mutation power calculation module 501 , a second adder 502 , a transient feedforward value calculation module 503 , a second data storage module 504 , and a pre-mutation power calculation module 505 .

[0096] The specific working process of the power feedforward module 206 is as follows:

[0097] S600: Get output voltage V o , regulator pre-output value v er_on ;

[0098] S601: Based on the output voltage V sampled in this calculation cycle o And the output voltage V of the first N calculation cycles stored o -N Calculate the power P of transient mutation o_short ;

[0099] S602: Based on the regulator expected value v stored in the previous N calculation cycles er_exp -N Calculate the converter power P before the sudden change o_last ;

[0100] S603: Calculate the total power P after the converter load changes suddenly o_total ;

[0101] S604: According to the total power P after the sudden change of the converter load o_total And the obtained regulator pre-output value v er_on Calculate the power feedforward compensation value v er_short ;

[0102] S605: Store the output voltage value, let V o -N =V o ;

[0103] S606: Store the regulator expected value, let v er_exp -N =v er_exp ;

[0104] S607 waits for the next calculation cycle.

[0105] In this embodiment, the first data storage module 500 is used to store the output voltage value V during the first N calculation cycles. o -N When N=1, the output of the first data storage module 500 is the output voltage sampling value V of the previous calculation cycle. o -1 When N=2, the output of the first data storage module 500 is the output voltage sampling value V of the first two calculation cycles. o -2 ; and so on.

[0106] The transient power calculation module 501 is based on the output voltage V sampled in the current cycle. o And the stored output voltage V of the first N cycles o -N The power of the transient mutation is calculated using formula (17) for the two input signals and is recorded as P o_short , and use this as the output of the transient mutation power calculation module 501.

[0107] The second adder 502 is used to calculate the output power after the load mutation, which is denoted as P o_total .

[0108] The transient feedforward value calculation module 503 calculates the total power P after the load mutation according to the calculation. o_total The value required for feedforward compensation is calculated using formula (15) and the regulator output value as the input signal of the first adder 205.

[0109] The second data storage module 504 is used to store the v of the first N calculation cycles. er_exp It is worth noting that the value of N of the second data storage module 504 is the same as that of the first data storage module 500.

[0110] The power calculation module 505 before the load mutation uses formula (16) to calculate the output power of the converter before the load mutation. The total power of the converter after the load mutation can be obtained by adding it to the transient mutation power. The total power expression of the converter is:

[0111] P o_total =P o_last +P o_short (15)

[0112] Obviously, combined with formula (12), the output result P of the power calculation module 505 before the mutation can be obtained. o_last The expression:

[0113]

[0114] Among them, v er_exp -N is the regulator expected value of the first N control calculation cycles, and correspondingly, P o_last is the output power of the first N calculation cycles. The output result P of the transient mutation power calculation module 501 is o_short The voltage change of the filter capacitor can be obtained:

[0115]

[0116] Among them, V o V is the converter output voltage sampled in the current calculation cycle; o -N is the converter output voltage value sampled in the first N calculation cycles, and the value of N is the same as the above v er_exp -N The value of N in the equation is the same; f ctrl Calculate the frequency for digital control. Therefore, combining equations (12), (15), (16), and (17) can yield the desired regulator output after a sudden load change:

[0117]

[0118] Since the current calculation cycle has generated an output v through pi regulation er_on , so that the final output adjustment result is v er_exp , the output result of the transient feedforward value calculation module 503, that is, the output result v of the power feedforward module 206 er_short The expression is:

[0119] v er_short =v er_exp -v er_on (19)

[0120] Right now

[0121]

[0122] Where C f Indicates the converter output filter capacitor; L m Represents the magnetizing inductance of the transformer in the converter; f s Indicates the switching frequency of the converter; f ctrl Indicates the converter control calculation frequency; N indicates the number of control calculation cycles between the control calculation cycle in which the variable value stored for calculating the power feedforward compensation value is located and the current control calculation cycle, and N is a positive integer greater than or equal to 1; V o Indicates the converter output voltage sampled during the current control calculation cycle; V o -N Indicates the output voltage value during the first N control calculation cycles; v er_exp -N It represents the expected value of the regulator calculated in the first N control calculation cycles.

[0123] From the above analysis, it can be seen that, in theory, the power feedforward algorithm can achieve accurate load jump power compensation within one calculation cycle at the shortest, and achieve a fast and accurate load mutation response without affecting the stability of the converter.

[0124] like Figure 7 As shown, taking N=1 as an example, with respect to the working process of the power feedforward module 206, the present invention also includes a converter dynamic response improvement algorithm based on power feedforward, including the following steps:

[0125] Step S700: Sample the input voltage V of the converter in and the output voltage V o ;

[0126] Step S701: The subtractor 200 converts the sampled output voltage V o With the preset output voltage V o Closed loop reference value V o_ref The output voltage error v o_error ;

[0127] Step S702: The regulator 201 performs closed-loop regulation calculation: in this embodiment, a proportional-integral regulator is used;

[0128] Step S703: The power feedforward module 206 calculates the power feedforward compensation value v according to equation (20) er_sh ort,;

[0129] Step S704: The first adder 203 sums the results of step S702 and step S703 to obtain the regulator expected value v er_exp ;

[0130] Step S705: The input voltage V in and the regulator expected value v er_exp Input T1-T2 calculation module 204, T1-T2 calculation module 204 calculates the conduction time T1 and T2 of the first switch tube Q1 and the second switch tube Q2;

[0131] Step S706: the PWM generation module 205 generates a PWM wave according to the on-times T1 and T2 of the first switch tube Q1 and the second switch tube Q2, so as to drive the first switch tube Q1 and the second switch tube Q2;

[0132] Step S707: The output voltage V sampled in this calculation cycle is o Stored in V o -1 Variable, used for calculating the power feedforward compensation value in the next cycle;

[0133] Step S708: Store the regulator expected value calculated in this cycle into v er_exp -1 Variable, used for calculating the power feedforward compensation value in the next cycle;

[0134] Step S709: Wait for the next calculation cycle.

[0135] In summary, the algorithm of the present invention actually superimposes a power feedforward compensation value on the regulator calculation result, as shown in formula (20), to obtain the regulator output expected for the new load state, thereby achieving a fast and accurate dynamic compensation effect. In order to reduce the calculation pressure of the controller, the calculation method of the power feedforward compensation value can also be simplified. A simplified result of formula (20) is given below:

[0136]

[0137] It should be noted that any algorithm that is simplified or approximated based on formula (20) falls within the scope of protection of the present invention.

[0138] In addition, power feedforward compensation calculation does not need to be performed in every calculation cycle. Conditional judgment can be added to the power feedforward module, such as Figure 8 As shown, the specific workflow of the control algorithm with the judgment condition added to the power feedforward module is given, which is divided into steps 800 to 811. It should be noted that power feedforward compensation algorithms using other judgment conditions also fall within the scope of protection of the present invention.

[0139] Step 800: Sample the input voltage V of the converter in and the output voltage V o ;

[0140] Step 801: The subtractor 200 subtracts the sampled output voltage V o With the preset output voltage V o Closed loop reference value V o_ref The output voltage error v o_error ;

[0141] Step 802: The regulator 201 performs closed-loop regulation calculation: In this embodiment, a proportional-integral regulator is used; In this embodiment, a proportional-integral regulator is used;

[0142] Step 803: Determine the voltage error v obtained in step 801 o_error Is it greater than the preset value v o_error_th If yes, go to step 804, if no, go to step 805;

[0143] Step 804: Calculate the power feedforward compensation value v according to equation (20) er_short , where V o -1 is the result of step 809 in the previous calculation cycle, v er_exp -1 is the result of step 810 in the previous calculation cycle;

[0144] Step 805: Directly change v er_short Assign 0;

[0145] Step 806: The first adder 203 sums the results of step 802 and step 804 to obtain the regulator expected value v er_exp ;

[0146] Step 807: Set the converter input voltage V in and the regulator expected value v er_exp Input T1-T2 calculation module 204, T1-T2 calculation module 204 calculates the conduction time T1 and T2 of the first switch tube Q1 and the second switch tube Q2;

[0147] Step 808: The PWM generation module 205 generates a PWM wave according to the on-times T1 and T2, for driving the first switch tube Q1 and the second switch tube Q2;

[0148] Step 809: The output voltage V sampled in this calculation cycle is o Stored in V o -1 Variable, used for calculating the power feedforward compensation value in the next cycle;

[0149] Step 810: Store the regulator expected value calculated in this cycle into v er_exp -1Variable, used for calculating the power feedforward compensation value in the next cycle;

[0150] Step 811: Wait for the next calculation cycle.

[0151] In order to further illustrate the technical effect of this solution, under the conditions of input voltage 28V, output voltage 12V, and using proportional-integral regulator, the dynamic experimental waveforms of no-load switching to full-load with and without the power feedforward compensation algorithm are compared. Figure 9 is the experimental waveform without power feedforward compensation, Figure 10 This is the experimental waveform using power feedforward compensation. Obviously, the output voltage drop and response time under the power feedforward compensation algorithm are significantly better than the solution using only proportional-integral regulator.

Claims

1. A method for improving the dynamic response of a converter based on power feedforward, characterized in that: For an active clamp flyback converter, the method comprises the following steps: S1: Determine the output voltage error v of the converter o_erorr , and perform pre-regulation calculation of the regulator to obtain the regulator pre-output value v er_on ; S2: Based on the output voltage V o , regulator pre-output value v er_on and the regulator expected value v of the first N control calculation cycles er_exp -N , calculate the power feedforward compensation value v er_short ; S3: Set the regulator pre-output value v er_on and power feedforward compensation value v er_short Add together to get the regulator expected value v of the current control calculation cycle er_exp ; S4: adjusting the output voltage of the converter based on the regulator expected value calculation result of the current control calculation cycle; In step S1, the output voltage error v of the converter is determined o_error , and perform pre-regulation calculation of the regulator to obtain the regulator pre-output value v er_on , specifically including the following: First, the input voltage V in and the output voltage V o ; Then the sampled output voltage V o With the preset output voltage V o Closed loop reference value V o_ref The output voltage error v of the converter is obtained by subtracting o_error ; Then according to the output voltage error v of the converter o_error , perform pre-regulation calculation of the regulator. The pre-regulation calculation of the regulator includes, first, performing regulator compensation calculation to obtain the regulator compensation output value v er , the regulator compensates the output value v er Perform limiting processing to obtain the regulator pre-output value v er_on ; In step S2, the power feedforward compensation value v er_short The expression is: Where C f Indicates the converter output filter capacitor; L m Represents the magnetizing inductance of the transformer in the converter; f s Indicates the converter switching frequency; f ctrl Indicates the converter control calculation frequency; N indicates the number of control calculation cycles between the control calculation cycle in which the variable value stored for calculating the power feedforward compensation value is located and the current control calculation cycle; N is a positive integer greater than or equal to 1; V o Indicates the converter output voltage sampled during the current control calculation cycle; V o -N Indicates the output voltage value during the first N control calculation cycles; v er_exp -N It represents the expected value of the regulator calculated in the first N control calculation cycles.

2. The method for improving converter dynamic response based on power feedforward according to claim 1, characterized in that: In step S4, the output voltage of the converter is adjusted based on the regulator expected value calculation result of the current control calculation cycle, specifically including the following: According to the input voltage V in and the regulator expected value v er_exp , calculate the conduction time T1 and T2 of the main power switch tube Q1 and the clamp switch tube Q2; A PWM wave is generated according to the on-times T1 and T2 of the main power switch tube Q1 and the clamp switch tube Q2 to drive the main power switch tube Q1 and the clamp switch tube Q2.

3. The method for improving converter dynamic response based on power feedforward according to claim 1, characterized in that: By adding a judgment condition before step S2, it is possible to judge whether the power feedforward compensation value v needs to be calculated in different calculation cycles. er_short ; The judgment condition is to judge the voltage error v o_error Is it greater than the preset value v o_error_th If so, calculate the power feedforward compensation value v er_short If not, then directly set v er_short Equal to zero.

4. A device for improving the dynamic response of a converter based on power feedforward, characterized in that: The device adopts the method for improving the dynamic response of the converter based on power feedforward according to claim 1, and the device includes: Subtractor module (200) for determining the output voltage error v o_erorr ; Converter pre-regulation module is used to adjust the output voltage based on the output voltage error v o_erorr Perform loop compensation calculation and limit the calculation result to obtain the regulator pre-output value v er_on ; The power feedforward module (206) is used to calculate the power feedforward compensation value v er_short ; The first adder module (203) is used to calculate the regulator expected value v er_exp ; an output voltage adjustment module, configured to adjust the output voltage of the converter based on a regulator desired value; Wherein, the subtractor module (200), the converter pre-regulation module, the first adder module (203), and the output voltage adjustment module are connected in sequence; The input signal of the first input terminal of the power feedforward module (206) is the converter output voltage V o , the second input end is connected to the output end of the converter pre-regulation module, the third input end is connected to the output end of the first adder module (203), and the output end of the power feedforward module (206) is connected to the input end of the first adder module (203); The regulator pre-output value v er_on is calculated as follows: First, the input voltage V in and the output voltage V o ; Then the sampled output voltage V o With the preset output voltage V o Closed loop reference value V o_ref The output voltage error v of the converter is obtained by subtracting o_error ; Then according to the output voltage error v of the converter o_error , perform pre-regulation calculation of the regulator. The pre-regulation calculation of the regulator includes, first, performing regulator compensation calculation to obtain the regulator compensation output value v er , the regulator compensates the output value v er Perform limiting processing to obtain the regulator pre-output value v er_on ; The power feedforward compensation value v er_short The expression is: Where C f Indicates the converter output filter capacitor; L m Represents the magnetizing inductance of the transformer in the converter; f s Indicates the converter switching frequency; f ctrl Indicates the converter control calculation frequency; N indicates the number of control calculation cycles between the control calculation cycle in which the variable value stored for calculating the power feedforward compensation value is located and the current control calculation cycle; N is a positive integer greater than or equal to 1; V o Indicates the converter output voltage sampled during the current control calculation cycle; V o -N Indicates the output voltage value during the first N control calculation cycles; v er_exp -N It represents the expected value of the regulator calculated in the first N control calculation cycles.

5. The device for boosting converter dynamic response based on power feedforward according to claim 4, characterized in that: The power feedforward module comprises a first data storage module (500), a transient mutation power calculation module (501), an adder (502), a transient feedforward value calculation module (503), a second data storage module (504), and a pre-mutation power calculation module (505); The first data storage module (500), the transient mutation power calculation module (501), the adder (502), and the transient feedforward value calculation module (503) are connected in sequence; the second data storage module (504) is connected to the pre-mutation power calculation module (505); and the output end of the pre-mutation power calculation module (505) is connected to the second adder (502).

6. The device for boosting converter dynamic response based on power feedforward according to claim 5, characterized in that: The first data storage module (500) is used to store the output voltage value V during the first N control calculation cycles. o -N ; The transient power calculation module (501) is based on the output voltage V sampled in the current control calculation period. o And the stored output voltage V of the first N control calculation cycles o -N Calculate the power P of transient mutation o_short : Where C f Indicates the converter output filter capacitor; f ctrl Indicates the converter control calculation frequency; The second data storage module (504) stores the regulator expected value v of the first N control calculation cycles er_exp -N ; The power calculation module (505) before the mutation is based on the regulator expected value v of the first N control calculation cycles. er_exp -N Calculate the output power P of the converter in the first N control calculation cycles before the load mutation o_last : Among them, L m Indicates the magnetizing inductance value, f s represents the switching frequency of the converter; The second adder (502) converts the transient power P o_short and the output power P of the converter in the first N control calculation cycles before the load mutation o_last Add up to get the total power P after the load mutation o_total ; The transient feedforward value calculation module (503) is used to calculate the total power P after the load mutation obtained by calculation. o_total And the regulator pre-output value v er_on Calculate the power feedforward compensation value v er_short , which serves as the input signal of the first adder module (203).

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