Current reference quantity feedforward compensation control method and system

Abstract

The invention relates to a current reference quantity feed-forward compensation control method and system. The control method comprises the following steps: determining a current inductive current reference value of a triangular wave type power electronic converter; obtaining a PI control component based on the current inductive current reference value; subtracting the current inductive current reference value from the inductive current reference value of the previous period to obtain an inductive current reference value variable quantity; feedforward operation is carried out according to the inductance current reference value variable quantity and the working condition parameters of the triangular wave type power electronic converter, and a feedforward compensation component is obtained; and summing the PI control component and the feed-forward compensation component to generate a duty ratio so as to realize control of the triangular wave type power electronic converter. According to the current reference quantity feed-forward compensation control method and system provided by the invention, the tracking speed of the triangular wave type power electronic converter can be improved on the premise of not influencing the control precision of the triangular wave type power electronic converter.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a current reference quantity feedforward compensation control method and system. Background Art

[0002] A triangular wave power electronic converter refers to a power electronic converter whose inductor current is a triangular wave during normal operation, such as Buck, Boost and other topologies. Its working principle is low in complexity and easy to analyze and control. It has been widely used in many aspects of industrial production and daily life. Most triangular wave power electronic converters adopt a dual-loop control method, in which the control method and control target of the outer loop vary according to the specific application scenario of the converter; since the regulation of the converter working condition is essentially the control of its inductor current, the inner loop of the triangular wave power electronic converter is mostly a current PI control loop. Therefore, the control characteristics of the current loop directly affect the dynamic performance of the power electronic converter.

[0003] The current loop controller based on traditional PI control has a contradiction between tracking speed and accuracy. If the controller tracking speed is too fast, it may cause waveform distortion and spikes, which will reduce the working reliability of the triangular wave power electronic converter; and if the controller tracking accuracy is overemphasized, it may cause the inductor current to converge slowly. In situations where the inductor current has time-varying characteristics such as square wave ballasts and PFC rectifiers, or in the transient process of load switching, the insufficient current loop tracking speed will affect the converter performance, resulting in low power factor, waveform distortion, increased loss and other problems.

[0004] Therefore, developing and improving the current loop control characteristics of triangular wave power electronic converters is of great significance for improving the tracking speed and accuracy of the converter. Summary of the invention

[0005] Based on this, the present application provides a current reference feedforward compensation control method and system, which is particularly suitable for systems with time-varying current settings, such as square wave current ballasts and PFC rectifiers, and can improve the tracking speed of triangular wave power electronic converters without affecting the control accuracy.

[0006] The present application provides a current reference quantity feedforward compensation control method, comprising: S1: determining a current inductor current reference value of a triangular wave power electronic converter; S2: obtaining a PI control component based on the current inductor current reference value; S3: subtracting the current inductor current reference value from the inductor current reference value of a previous cycle to obtain a change in the inductor current reference value; performing a feedforward operation according to the change in the inductor current reference value and an operating parameter of the triangular wave power electronic converter to obtain a feedforward compensation component; S4: summing the PI control component and the feedforward compensation component to generate a duty cycle, and controlling the triangular wave power electronic converter.

[0007] Preferably, in step S3, the operating parameters include: power inductance value, voltage across the power inductor, switching period; the feedforward compensation component Δ D The calculation formula is:

[0008]

[0009] in, is the change of the inductor current reference value, is the power inductor value, is the voltage across the power inductor, is the switching cycle.

[0010] Preferably, step S3 further comprises: using the current inductor current reference value to cover the inductor current reference value of the previous cycle for calculation in the next cycle.

[0011] Preferably, step S1 comprises: processing the sampling value of the triangular wave power electronic converter through an outer loop controller to obtain a current inductor current reference value; the sampling value comprises: an input voltage instantaneous value and an output voltage instantaneous value.

[0012] Preferably, step S1 comprises: subtracting a predetermined output voltage reference value from the instantaneous value of the output voltage to generate an output voltage error value; performing PI calculation on the output voltage error value to obtain a voltage PI result; calculating the instantaneous value of the input voltage through a phase-locked loop to obtain an input voltage phase sine value, and multiplying the input voltage phase sine value by the voltage PI result to generate the current inductor current reference value.

[0013] Preferably, the sampling value also includes: an instantaneous value of the inductor current; the step S2 includes: subtracting the current inductor current reference value from the instantaneous value of the inductor current to generate an inductor current error value; and calculating the inductor current error value using a PI controller to generate a PI control component.

[0014] The present application also provides a current reference feedforward compensation control system, comprising: a sampling unit, which obtains a sampling value of a triangular wave power electronic converter; an outer loop controller, which calculates and processes the sampling value to generate a current inductor current reference value; a current PI calculation unit, which obtains a PI control component based on the current inductor current reference value; a compensation component calculation unit, which subtracts the current inductor current reference value from the inductor current reference value of the previous cycle to obtain a change in the inductor current reference value; a feedforward operation is performed based on the change in the inductor current reference value and the operating parameters of the triangular wave power electronic converter to obtain a feedforward compensation component; a duty cycle calculation unit, which sums the PI control component and the feedforward compensation component to generate a duty cycle to control the triangular wave power electronic converter.

[0015] Preferably, the sampling values ​​include: an instantaneous value of the inductor current, an instantaneous value of the input voltage, and an instantaneous value of the output voltage; the outer loop controller processes the instantaneous value of the input voltage and the instantaneous value of the output voltage to obtain a current reference value of the inductor current.

[0016] Preferably, the current PI calculation unit generates an inductor current error value by subtracting the current inductor current reference value from the inductor current instantaneous value; and performs PI calculation on the inductor current error value using a PI controller to generate a PI control component.

[0017] Preferably, the operating parameters include: power inductance, voltage across the power inductor, and switching period; the feedforward compensation component Δ D The calculation formula is:

[0018]

[0019] in, is the change of the inductor current reference value, is the power inductor value, is the voltage across the power inductor, is the switching cycle.

[0020] The current reference quantity feedforward compensation control method and system provided in the present application calculate the feedforward compensation component based on the operating parameters of the triangular wave power electronic converter and the variation of the inductor current reference value, and add the feedforward compensation component to the calculation of the duty cycle. For power electronic converters with time-varying reference currents such as square wave ballasts and PFC rectifiers, the feedforward compensation control method of the present application can quickly output the desired compensation duty cycle when the reference current changes, which can effectively improve the dynamic performance, shorten the transient transition time, reduce overshoot, and make the PI controller focus on the regulation and suppression of small errors, thereby improving the performance of the triangular wave power electronic converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 This is a flow chart of the current reference feedforward compensation control method according to an embodiment of the present application.

[0023] Figure 2 Schematic diagram of the inductor current of the triangular wave power electronic converter according to an embodiment of the present application.

[0024] Figure 3 Schematic diagram of the structure of the current reference feedforward compensation control system according to an embodiment of the present application.

[0025] Figure 4 Schematic diagram of the topological structure of a bridgeless totem pole PFC rectifier according to an embodiment of the present application.

[0026] Figure 5 This is a schematic diagram of the control system structure of a bridgeless totem pole PFC rectifier according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0028] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0029] like Figure 1 As shown, this embodiment provides a current reference feedforward compensation control method, including.

[0030] Step S1: Determine the current reference value of the inductor current of the triangular wave power electronic converter .

[0031] Here, the input voltage, inductor current and output voltage of the triangular wave power electronic converter are sampled to obtain the corresponding sampled data. Preferably, the inductor current, input voltage and output voltage of the triangular wave power electronic converter are sampled to obtain the following sampled values: the instantaneous value of the inductor current , Input voltage instantaneous value V in_sensed , output voltage instantaneous value V o_sensed .

[0032] It can be understood that the control target, control method and control parameters of the outer loop controller should be designed according to the actual converter requirements, such as the voltage PI control loop, the power hysteresis control loop, etc.

[0033] In step S1, the instantaneous value of the input voltage V in_sensed And the instantaneous value of output voltage V o_sensed The current inductor current reference value is obtained through the outer loop PI controller .

[0034] Specifically, the predetermined output voltage reference value V o_ref The instantaneous value of the output voltage V o_sensed The output voltage error value V err ; Output voltage error value V err Perform PI calculation and obtain the voltage PI result V PI ; The instantaneous value of the input voltage V in_sensed The input voltage phase sine value is calculated by the phase-locked loop , the input voltage phase sine value The voltage PI results with V PI The current inductor current reference value is generated by multiplying .

[0035] It can be understood that the predetermined output voltage reference value V o_ref It is a voltage value given in advance according to actual needs.

[0036] Step S2: Based on the current inductor current reference value Get PI control component D PI .

[0037] Preferably, the current inductor current reference value The instantaneous value of the inductor current The difference is used to generate the inductor current error value ; Use the PI controller to calculate the inductor current error value Calculate and generate PI control components D PI .

[0038] It can be understood that the proportional parameter and the integral parameter of the PI controller are both given parameters.

[0039] Step S3: The current inductor current reference value Subtract the inductor current reference value from the previous cycle to obtain the inductor current reference value change ; According to the change of the inductor current reference value The feedforward operation is performed on the operating parameters of the triangular wave power electronic converter to obtain the feedforward compensation component .

[0040] Figure 2 The inductor current in the triangular wave power electronic converter is shown in The waveform of When the main switch is turned on and the synchronous rectifier is turned off, the inductor current It shows an upward trend; when the main switch tube is turned off and the synchronous rectifier tube is turned on, the inductor current According to the inductor characteristics, the inductor current Change rate and inductor voltage And power inductor value The following relationship exists:

[0041]

[0042] Inductor Current At any time interval The amount of change within It can be calculated by the following formula:

[0043]

[0044] In two adjacent switching cycles, if the inductor current reference value of the current cycle is changes, the duty cycle of the main switch D must be adjusted accordingly so that the inductor current From the current average inductor current Transition to the current inductor current reference value . Duty Cycle D The adjustment speed and accuracy have a decisive influence on the working performance of the converter. D Adjustment amount The change of the inductor current reference value There are the following relationships:

[0045]

[0046] Understandably, The physical meaning is: when the inductor current reference value occurs between the two switching cycles before and after When the current changes, the duty cycle adjustment required for timely current tracking is realized. Among them, It is the voltage across the power inductor when the main switch is on and the synchronous rectifier is off. Its calculation method is determined according to the actual topology of the converter. is the switching cycle.

[0047] The existing traditional PI controller is based on a feedback control structure and must start the corresponding adjustment after the error occurs. At the same time, the traditional PI controller does not have an accurate calculation for the above theoretical adjustment amount. Therefore, for the traditional PI controller, the transient process of the above current adjustment will generally last for 2-3 switching cycles or even longer, and may be accompanied by current overshoot spikes.

[0048] In this embodiment, the duty cycle adjustment amount Directly as the feedforward compensation component, therefore, the feedforward compensation component The calculation formula is:

[0049]

[0050] Preferably, the operating parameters include: power inductance value , the voltage across the power inductor , switching cycle As an example, when the triangular wave power electronic converter is a bridgeless totem pole PFC converter, It is the voltage across the power inductor when the main switch is on and the synchronous rectifier is off.

[0051] Preferably, after the above step S3 is executed, the current inductor current reference value is also used. Overwrite the inductor current reference value of the previous cycle for calculation in the next cycle.

[0052] That is to say, the current inductor current reference value As the reference value of the inductor current in the previous cycle in the next cycle operation.

[0053] Step S4: The PI control component D PI With the feedforward compensation component The sum is calculated to generate a duty cycle and control the triangular wave power electronic converter.

[0054] Here, the feedforward compensation component With PI control component D PI Add together to form the duty cycle D In this embodiment, a feedforward control structure is added to the controller architecture, and the inductor current reference value The duty cycle is adjusted accurately and directly at the same time as the change occurs, without waiting for the error to occur, which also saves the adjustment time of the PI controller, thereby improving the tracking speed of the triangular wave power electronic converter without affecting the control accuracy, thereby significantly improving the tracking performance of the triangular wave power electronic converter.

[0055] like Figure 3 As shown, an embodiment of the present application also provides a current reference feedforward compensation control system, including: a sampling unit 1, an outer loop controller 2, a current PI calculation unit 3, a compensation component calculation unit 4, and a duty cycle calculation unit 5.

[0056] Sampling unit 1 obtains the sampling value of the triangular wave power electronic converter: the instantaneous value of the inductor current , Input voltage instantaneous value V in_sensed , output voltage instantaneous value V o_sensed .

[0057] The outer loop controller 2 calculates and processes the sampled value to generate a current inductor current reference value. .

[0058] Preferably, the outer loop controller sets the predetermined output voltage reference value V o_ref The instantaneous value of the output voltage V o_sensed The output voltage error value V err ; Output voltage error value V err Perform PI calculation and obtain the voltage PI result V PI ; The instantaneous value of the input voltage V in_sensed The phase-locked loop calculates the input voltage phase sine value phase_sin, and the input voltage phase sine value phase_sin is compared with the voltage PI result V PI The current inductor current reference value is generated by multiplying .

[0059] The current PI calculation unit 3 converts the current inductor current reference value The instantaneous value of the inductor current The difference is used to generate the inductor current error value ; Use the PI controller to calculate the inductor current error value Perform PI calculations to generate PI control components D PI .

[0060] The compensation component calculation unit 4 converts the current inductor current reference value Subtract the inductor current reference value from the previous cycle to obtain the inductor current reference value change ; and according to the change in the inductor current reference value The feedforward operation is performed on the operating parameters of the triangular wave power electronic converter to obtain the feedforward compensation component Afterwards, the compensation component calculation unit 4 also uses the current inductor current reference value Overwrite the inductor current reference value of the previous cycle for calculation in the next cycle.

[0061] The duty cycle calculation unit 5 converts the PI control component D PI With the feedforward compensation component Summing to generate duty cycle D , which is used to control the on and off of the switching devices in the triangular wave power electronic converter, thereby realizing the control of the triangular wave power electronic converter.

[0062] like Figure 4 As shown, the bridgeless totem pole PFC rectifier topology is taken as an example to explain the embodiment of the present application in detail, V in is the AC input voltage of the bridgeless totem pole PFC converter, V o is the DC output voltage of the bridgeless totem pole PFC converter, to the AC input voltage V in Sampling to obtain the instantaneous value of input voltage V in_sensed , for DC output voltage V o Sampling to obtain the instantaneous value of the output voltage V o_sensed . Low frequency tube (low frequency upper tube Q L_1 , low frequency down tube Q L_2 ) provides different paths for the output current, thereby changing the direction of the output current and achieving the rectification function. Q H_1 With high frequency down tube Q H_2 The control system of this embodiment controls the duty cycle of the active switch tube in the high frequency tube. D , to control the instantaneous value of the inductor current, so as to stabilize the output voltage at the required voltage level, and the synchronous rectifier tube drive signal is complementary to the active switch tube. In this embodiment, the control method adopts voltage-current dual closed-loop control, so the outer loop controller is a voltage PI controller, and the voltage across the power inductor is is the instantaneous value of the input voltage V in_sensed In this embodiment, the control system can be implemented by a DSP controller or an analog control circuit.

[0063] like Figure 5As shown, if a DSP controller is used for software control, when the totem pole PFC rectifier is turned on, the control system adjusts the output voltage reference value V according to the preset value of the program. o_ref , voltage PI control parameters, current PI control parameters are initialized, and program interrupt initialization settings are performed based on the preset switching frequency; after the initialization is completed, the totem pole PFC rectifier enters the stable operation stage, and the control system function code is placed in the interrupt program; the CPU controls the sampling unit 1 hardware circuit to sample the actual physical quantity according to the switching frequency, and triggers an interrupt after the sampling is completed, and generates the instantaneous value of the inductor current in the interrupt program , Input voltage instantaneous value V in_sensed , output voltage instantaneous value V o_sensed The voltage PI calculation unit in the outer loop controller 2 uses the output voltage reference value V o_ref The instantaneous value of the output voltage V o_sensed The output voltage error value V err , the output voltage error value V err Perform PI calculation to get the voltage PI result V PI ; The instantaneous value of the input voltage V in_sensed The input voltage phase sine value is calculated by the phase-locked loop , the input voltage phase sine value The voltage PI results with V PI The current inductor current reference value is generated by multiplying the current inductor current by the multiplier. The current PI calculation unit 3 converts the current inductor current reference value The instantaneous value of the inductor current The difference is used to generate the inductor current error value ; Using the current PI controller to the inductor current error value Perform PI calculations to generate PI control components D PI When the main switch is turned on, the voltage across the power inductor is the instantaneous value of the input voltage V in_sensed , then the compensation component calculation unit 4 uses the instantaneous value of the input voltage V in_sensed , power inductor value , switching cycle And the change of inductor current reference value Calculate and generate the feedforward compensation components The duty cycle calculation unit 5 is used for the PI control component D PI With the feedforward compensation component Summing to generate duty cycle D, input into the PWM modulation module of the DSP controller to update the control signals of each active switch tube and synchronous rectifier tube, and output from the DSP controller pin to the control pin of the corresponding switch device, thereby controlling the action of the switch device and realizing the function of the control system.

[0064] In another embodiment, if an analog control circuit is used for hardware control, the parameters required by the controller are confirmed according to the working condition requirements of the converter, and an analog operation circuit composed of multiple circuit components is designed accordingly. In specific work, the above control process is completed by the operation circuit, and a PWM control signal is generated and output to the control pin of the corresponding switch device to realize the control of the bridgeless totem pole PFC rectifier.

[0065] The current reference feedforward compensation control method and system provided in this embodiment calculates the feedforward compensation component based on the operating parameters of the triangular wave power electronic converter and the change in the inductor current reference value, and adds the feedforward compensation component to the calculation of the duty cycle. The control method can improve its tracking speed without affecting the control accuracy of the controller, ensuring that the inductor current reaches its set value quickly and accurately, which is conducive to improving the working efficiency and dynamic performance of the triangular wave power electronic converter. In addition, the early response to the change in current reference can effectively improve the dynamic performance, shorten the transient transition time, reduce overshoot, and make the PI controller focus on the regulation and suppression of small errors, thereby improving the performance of the triangular wave power electronic converter.

[0066] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A current reference feedforward compensation control method, characterized in that: include: S1: Determine the current inductor current reference value of the triangular wave power electronic converter; S2: Obtaining a PI control component based on the current inductor current reference value; S3: subtracting the current inductor current reference value from the inductor current reference value of the previous cycle to obtain an inductor current reference value variation; performing a feedforward operation according to the inductor current reference value variation and the operating parameters of the triangular wave power electronic converter to obtain a feedforward compensation component; S4: summing the PI control component and the feedforward compensation component to generate a duty cycle, and controlling the triangular wave power electronic converter.

2. The current reference feedforward compensation control method according to claim 1, characterized in that: In step S3, the operating parameters include: power inductance value, voltage across the power inductor, and switching cycle; The feedforward compensation component The calculation formula is: in, is the change of the inductor current reference value, is the power inductor value, is the voltage across the power inductor, is the switching cycle.

3. The current reference feedforward compensation control method according to claim 1, characterized in that: Step S3 also includes: using the current inductor current reference value to cover the inductor current reference value of the previous cycle for calculation in the next cycle.

4. The current reference feedforward compensation control method according to claim 1, characterized in that: Step S1 includes: The sampling value of the triangular wave power electronic converter is processed by an outer loop controller to obtain a current inductor current reference value; The sampled values ​​include: an instantaneous value of an input voltage and an instantaneous value of an output voltage.

5. The current reference feedforward compensation control method according to claim 4, characterized in that: The step S1 comprises: Subtracting a predetermined output voltage reference value from the instantaneous value of the output voltage to generate an output voltage error value; Perform PI calculation on the output voltage error value to obtain the voltage PI result; The instantaneous value of the input voltage is calculated by a phase-locked loop to obtain an input voltage phase sine value, and the input voltage phase sine value is multiplied by the voltage PI result to generate the current inductor current reference value.

6. The current reference feedforward compensation control method according to claim 4, characterized in that: The sampled values ​​also include: instantaneous value of inductor current; Step S2 includes: The current inductor current reference value is subtracted from the instantaneous value of the inductor current to generate an inductor current error value; the inductor current error value is calculated using a PI controller to generate a PI control component.

7. A current reference feedforward compensation control system, characterized in that: include: A sampling unit, for obtaining a sampling value of a triangular wave power electronic converter; The outer loop controller performs calculation processing on the sampled value to generate a current inductor current reference value; a current PI calculation unit, which obtains a PI control component based on the current inductor current reference value; A compensation component calculation unit is configured to obtain a change in the inductor current reference value by subtracting the current inductor current reference value from the inductor current reference value of the previous cycle; and to obtain a feedforward compensation component by performing a feedforward operation according to the change in the inductor current reference value and the operating parameters of the triangular wave power electronic converter. The duty cycle calculation unit sums the PI control component and the feedforward compensation component to generate a duty cycle and controls the triangular wave power electronic converter.

8. The current reference feedforward compensation control system according to claim 7, characterized in that: The sampling values ​​include: the instantaneous value of the inductor current, the instantaneous value of the input voltage, and the instantaneous value of the output voltage; The outer loop controller processes the instantaneous value of the input voltage and the instantaneous value of the output voltage to obtain a current inductor current reference value.

9. The current reference feedforward compensation control system according to claim 8, characterized in that: The current PI calculation unit generates an inductor current error value by subtracting the current inductor current reference value from the inductor current instantaneous value; and performs PI calculation on the inductor current error value by using a PI controller to generate a PI control component.

10. The current reference feedforward compensation control system according to claim 9, characterized in that: The operating parameters include: power inductance value, voltage across the power inductor, and switching cycle; The feedforward compensation component The calculation formula is: in, is the change of the inductor current reference value, is the power inductor value, is the voltage across the power inductor, is the switching cycle.

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