Load feedforward control method and system for power factor correction circuit

Abstract

The invention provides a power factor correction circuit load feedforward control method and system, and the method comprises the steps: obtaining a voltage control signal of a power factor correction circuit, collecting an output current signal of the power factor correction circuit, and collecting an inductive current signal of the power factor correction circuit; the duty ratio of a switch driving signal of the power factor correction circuit is calculated based on the voltage control signal, the output current signal and the inductive current signal, the voltage control signal and the duty ratio are in a homodromous growth relation, the output current signal and the duty ratio are in a homodromous growth relation, and the inductive current signal and the duty ratio are in a reverse growth relation; and on-off of a switching device of the power factor correction circuit is controlled according to the duty ratio of the switching driving signal. According to the invention, the duty ratio of the switch driving signal of the power factor correction circuit can be adaptively adjusted according to the output current signal, and rapid, stable and accurate voltage control is realized by predicting and compensating the influence of the load change on the output voltage.

Description

Technical Field

[0001] The present application relates to the technical field of power factor correction circuit control, and in particular to a power factor correction circuit load feedforward control method and system. Background Art

[0002] The welding power supply of welding equipment faces the challenges of large load changes and high dynamic characteristics during the welding process. The welding arc is a dynamic load, and its state is constantly changing during the welding process, causing the welding power supply to frequently switch between no-load, load and short-circuit states, with a large range of load changes. In addition, different welding processes and materials have different requirements for welding power supply output, further increasing the complexity of the load.

[0003] The dynamic characteristics of the welding power supply are crucial, as they determine its ability to adapt to load transients. Good dynamic characteristics require that the welding power supply can respond quickly to load changes, stabilize output voltage and current, avoid fluctuations and interference, and precisely control output parameters to obtain satisfactory weld quality. However, when the welding power supply is loaded instantaneously, the bus voltage often drops, which affects the stability and efficiency of the welding process. This phenomenon is mainly caused by a sudden increase in load, which causes a surge in current and then causes a drop in bus voltage. Summary of the invention

[0004] In response to the problems in the prior art, the purpose of the present application is to provide a load feedforward control method and system for a power factor correction circuit, which can adaptively adjust the duty cycle of the switch drive signal of the power factor correction circuit according to the output current signal, and achieve fast, stable and precise voltage control by predicting and compensating the impact of load changes on the output voltage.

[0005] The present application provides a power factor correction circuit load feedforward control method, including:

[0006] Acquire a voltage control signal of a power factor correction circuit, collect an output current signal of the power factor correction circuit, and collect an inductor current signal of the power factor correction circuit;

[0007] Calculating the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, wherein the voltage control signal and the duty cycle are in a same-direction growth relationship, the output current signal and the duty cycle are in a same-direction growth relationship, and the inductor current signal and the duty cycle are in a reverse-direction growth relationship;

[0008] The on and off of the switch device of the power factor correction circuit is controlled according to the duty cycle of the switch drive signal.

[0009] In some embodiments, calculating the duty cycle of the switch driving signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal includes:

[0010] Based on the function D = f1(I L R s ,K o I o ,V m ) calculates the duty cycle of the switch drive signal; where D is the duty cycle of the switch drive signal, I L is the inductor current signal, R s is the resistance of the current sampling resistor, K o is the load current feed-forward coefficient, I o is the output current signal, V m is the voltage control signal, and the function f1 satisfies: I L R s K has an inverse growth relationship with D. o I o V has the same growth relationship with D. m It has the same growth relationship with D.

[0011] In some embodiments, calculating the duty cycle of the switch driving signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal includes:

[0012] Obtaining a duty cycle increment ΔD; wherein the duty cycle increment and the output voltage signal of the power factor correction circuit are in an inverse growth relationship;

[0013] Based on the function D = f1(I L R S ,K o I o ,V m )+ΔD to calculate the duty cycle of the switch drive signal; where D is the duty cycle of the switch drive signal, I L is the inductor current signal, R s is the resistance of the current sampling resistor, K o is the load current feed-forward coefficient, I o is the output current signal, V m is the voltage control signal, and the function f1 satisfies: I L R s K has an inverse growth relationship with D. o I o V has the same growth relationship with D. m It has the same growth relationship with D.

[0014] In some embodiments, the duty cycle increment is calculated using the following formula:

[0015] ΔD=m*(V ref -V o )

[0016] Where m is the preset response coefficient, V ref is the preset voltage reference value, V o It is the output voltage signal of the power factor correction circuit.

[0017] In some embodiments, in calculating the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, before obtaining the duty cycle increment ΔD, the following steps are also included:

[0018] Determine whether the output circuit is short-circuited;

[0019] If not, ΔD is set to a preset minimum value;

[0020] If so, the duty cycle increment is determined based on the output voltage signal of the power factor correction circuit.

[0021] In some embodiments, before calculating the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, the following steps are also included:

[0022] Collecting input voltage signal of power factor correction circuit;

[0023] The load current feed-forward coefficient is calculated based on the input voltage signal.

[0024] In some embodiments, calculating the load current feed-forward coefficient according to the input voltage signal includes the following steps:

[0025] Calculate the RMS value of the input voltage signal;

[0026] Based on the function K o =f2(V inrms ) calculates the load current feed-forward coefficient; where V inrms is the RMS value of the input voltage signal, and function f2 satisfies: V inrms With K o It is a reverse growth relationship.

[0027] In some embodiments, obtaining a voltage control signal of a power factor correction circuit includes the following steps:

[0028] Collecting the output voltage signal of the power factor correction circuit;

[0029] A voltage control signal is obtained based on a preset voltage control algorithm according to the output voltage signal and a preset reference voltage.

[0030] In some embodiments, the preset voltage control algorithm is a proportional-integral control algorithm, in which the difference between the output voltage signal and the preset reference voltage is taken as the error.

[0031] The embodiment of the present application also provides a power factor correction circuit load feedforward control system, which is applied to a power factor correction circuit load feedforward control method, and the system includes:

[0032] A signal acquisition module, used to obtain a voltage control signal of a power factor correction circuit, to acquire an output current signal of the power factor correction circuit, and to acquire an inductor current signal of the power factor correction circuit;

[0033] A duty cycle calculation module, used to calculate the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, wherein the voltage control signal and the duty cycle are in a same-direction growth relationship, the output current signal and the duty cycle are in a same-direction growth relationship, and the inductor current signal and the duty cycle are in a reverse growth relationship;

[0034] The circuit control module is used to control the on and off of the switch device of the power factor correction circuit according to the duty cycle of the switch drive signal.

[0035] The power factor correction circuit load feedforward control method and system provided in this application have the following advantages:

[0036] By adopting the load feedforward control method of the power factor correction circuit of the present application, the duty cycle of the switch drive signal of the power factor correction circuit can be adaptively adjusted according to the output current signal, and the influence of load changes on the output voltage can be predicted and compensated to achieve fast, stable and precise voltage control, which is suitable for power supply scenarios with large load changes and high dynamic characteristics requirements such as welding equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings.

[0038] Figure 1 is a flow chart of a load feedforward control method of a power factor correction circuit according to an embodiment of the present application;

[0039] Figure 2 is a circuit diagram of a three-phase power factor correction circuit according to an embodiment of the present application;

[0040] Figure 3 is a circuit diagram of a single-phase power factor correction circuit according to an embodiment of the present application;

[0041] Figure 4 This is a flow chart of collecting various signals according to an embodiment of the present application;

[0042] Figure 5 is a schematic diagram of a duty cycle calculation process according to an embodiment of the present application;

[0043] Figure 6 is a flow chart of a duty cycle control circuit according to an embodiment of the present application;

[0044] Figure 7 It is a structural block diagram of a load feedforward control system of a power factor correction circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0045] The example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in a variety of forms and should not be construed as being limited to the embodiments set forth herein; on the contrary, these embodiments are provided so that the present application will be comprehensive and complete, and the concept of the example embodiments will be fully conveyed to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their repeated descriptions will be omitted. "Or" and "or" in the specification may both mean "and" or "or". Although the terms "upper", "lower", "between", etc. may be used in this specification to describe different exemplary features and elements of the present application, these terms are used herein only for convenience, such as according to the directions of the examples described in the accompanying drawings. Nothing in this specification should be construed as requiring a specific three-dimensional direction of the structure to fall within the scope of the present application. Although "first" or "second" etc. are used in this specification to represent certain features, they are only used to represent the function, and are not used as a limitation on the number and importance of specific features.

[0046] like Figure 1 As shown, the present application provides a load feedforward control method for a power factor correction circuit, comprising the following steps:

[0047] S100: acquiring a voltage control signal of a power factor correction circuit, collecting an output current signal of the power factor correction circuit, and collecting an inductor current signal of the power factor correction circuit;

[0048] The present application adopts a power factor correction circuit to control the output voltage of the driven device. The input end of the power factor correction circuit is connected to the power supply end (such as a power grid or a power supply device), and the output end of the power factor correction circuit outputs a working voltage and a working current. Taking the driven device as a welding device as an example, the output end of the power factor correction circuit outputs a welding voltage and a welding current.

[0049] The power factor correction circuit includes a rectifier circuit, an inductor, a switch device and an output capacitor. The voltage control signal is a voltage signal determined according to a preset reference voltage; the inductor current signal is a current signal flowing through the inductor, and the output current signal is a current output from the output end of the power factor correction circuit connected to the load;

[0050] S200: Calculating a duty cycle of a switch drive signal of a power factor correction circuit based on a voltage control signal, an output current signal, and an inductor current signal, wherein the voltage control signal and the duty cycle are in a same-direction increasing relationship, the output current signal and the duty cycle are in a same-direction increasing relationship, and the inductor current signal and the duty cycle are in a reverse-direction increasing relationship;

[0051] The voltage control signal and the duty cycle are in the same direction of growth, that is, the larger the voltage control signal, the larger the duty cycle, so that the output voltage of the power factor correction circuit can be quickly adjusted to the preset reference voltage; by predicting the change of the output current signal, the output of the driven device can be adjusted in advance according to the load characteristics and change rules to compensate for the impact of the load change on the output voltage;

[0052] S300: Control the on and off of the switch device of the power factor correction circuit according to the duty cycle of the switch drive signal. The switch drive signal is a PWM (Pulse-Width Modulation) signal, which controls the on and off of the switch device based on the duty cycle modulation PWM signal, thereby controlling the circuit output voltage. By accurately controlling the on and off time of the switch tube, the power factor correction circuit can significantly improve the power factor of the control system, reduce the reactive power loss at the power supply end, and effectively reduce the harmonic content of the input current, reduce the harmonic pollution to the power supply end, and protect the safe and stable operation of the power supply end and the driven equipment.

[0053] By adopting the load feedforward control method of the power factor correction circuit of the present application, the duty cycle of the switch drive signal of the power factor correction circuit can be adaptively adjusted according to the output current signal, and the influence of the load change on the output voltage can be predicted and compensated to achieve fast, stable and accurate voltage control, which is suitable for power supply scenarios with large load changes and high dynamic characteristics such as welding equipment. Taking the driven device as a welding device as an example, when the output end of the welding device is loaded instantly, the output voltage of the welding device will drop instantly, and the output current will increase. Since the voltage control signal and the duty cycle are in the same direction of growth, the difference between the output voltage and the preset reference voltage increases, which will increase the voltage control signal, thereby increasing the duty cycle under the influence of the voltage control signal, and the output current signal and the duty cycle are in the same direction of growth. Under the influence of the output current signal, the duty cycle is further increased, and the change of the output voltage can be quickly compensated, thereby maintaining the stability of welding and improving the welding quality. Therefore, the present application realizes the stable output and accurate control of the welding power supply by accurately predicting and compensating for load changes, which provides strong support for the optimization of the welding process.

[0054] Figure 2 The invention is a circuit diagram of a three-phase power factor correction circuit (PFC circuit). Figure 31 is a circuit diagram of a single-phase power factor correction circuit (PFC circuit) according to an embodiment of the present application. Figure 2 and Figure 3 As shown, the power factor correction circuit includes a rectifier module, a current acquisition module, a switch device and an output module. In the three-phase power factor correction circuit, the rectifier module includes diodes D1-D6, and in the single-phase power factor correction circuit, the rectifier module includes diodes D1-D4. The current acquisition module includes an inductor L1, an inductor L2 and a resistor CS, and the inductor L1 and the inductor L2 are Boost boost inductors. The current sampling signal collected by the resistor CS is the inductor current signal of the inductor L1 and the inductor L2. The first switch device Q1 and the second switch device Q2 are IGBTs (Insulated Gate Bipolar Transistors). The output module includes a diode D7, a diode D8, an output capacitor C1 and an output capacitor C2. Diodes D7 and D8 are SiC diodes. The rectifier module, the boost inductor, the switch device and the output module constitute a Boost circuit. In the power factor correction circuit, by connecting the first switch device and the second switch device in series and connecting them to the midpoint of the output module, dynamic voltage balancing of the output module capacitor can be achieved, so that the stress of the IGBT and the diode is halved. After the duty cycle of the switch drive signal is calculated by step S200, the duty cycles of the first switch device and the second switch device are the same, and the switch drive signal of the first switch device and the switch drive signal of the second switch device are staggered for half a cycle. The inductor current ripple can be reduced by phase shifting and staggered control of the two switch drive signals. The control method of the present application can be applied to a single-phase power factor correction circuit, and can also be applied to the control of a three-phase power factor correction circuit.

[0055] Figure 4 FIG. 4 shows a flow chart of collecting signals of this embodiment. Figure 4 As shown, after the driven device is turned on, the internal parameters of the device are initialized, and the initialized parameters include, for example, output current, output voltage, current sampling value, etc. It is determined whether the soft start of the driven device is completed. If not, it returns to the parameter initialization correction. After the soft start is completed, the output voltage signal is collected, and the voltage control signal is calculated based on the output voltage signal. In the step S100, the voltage control signal of the power factor correction circuit is obtained, including the following steps:

[0056] Collecting the output voltage signal of the power factor correction circuit;

[0057] According to the output voltage signal and the preset reference voltage, a voltage control signal is obtained based on a preset voltage control algorithm. In this embodiment, the preset voltage control algorithm is a proportional integral (PI) control algorithm, wherein the difference between the output voltage signal and the preset reference voltage is taken as an error, and the error is reduced by the proportional integral (PI) control algorithm so that the output voltage signal is as close to the preset reference voltage as possible. The preset reference voltage is the output voltage required by the driven device. Taking the driven device as a welding device as an example, the preset reference voltage is the required welding output voltage. By obtaining the voltage control signal through PI control, the output voltage can be accurately and stably controlled.

[0058] Then, the output current of the power factor correction circuit is collected as the output current signal, and the load current feedforward coefficient is calculated according to the input voltage signal. The load current feedforward coefficient mainly affects the influence of the output current signal on the duty cycle, that is, it is the relationship coefficient between the output current signal and the duty cycle. Among them, the load current feedforward coefficient is calculated according to the input voltage signal, including the following steps:

[0059] Calculate the input voltage signal V in The root mean square value V inrms ;

[0060] Based on the function K o =f2(V inrms ) Calculate the load current feed-forward coefficient K o ; Among them, function f2 satisfies: V inrms With K o It is an inverse growth relationship. That is, when the RMS value of the input voltage signal is larger, the load current feedforward coefficient K o The smaller the value, the smaller the effect of the output current signal change on the duty cycle. When the power factor correction circuit operates in a steady state, the output current is basically constant, and the output current feedforward has little effect on the duty cycle. When the output current suddenly changes, the output current feedforward can compensate for the problem of the voltage loop PI responding too slowly, and can quickly increase the duty cycle and increase the output voltage of the power factor correction circuit. When the input voltage is large, when the output end is suddenly loaded, the change in output voltage is relatively small. At this time, the compensation of the output current signal change for the duty cycle is small. When the input voltage is small, when the output end is suddenly loaded, the change in output voltage is relatively large. The output voltage may suddenly drop to a very low level, which is very unfavorable for the stability of the welding process. At this time, the output current signal change has a large compensation for the duty cycle, which can quickly increase the duty cycle and increase the output voltage of the power factor correction circuit.

[0061] For example, the load current feed-forward coefficient can be calculated using the following formula 1:

[0062]

[0063] Among them, V ref is the preset reference voltage, R s The above formula 1 is only an example. In other implementations, function f2 may also be in other forms, not limited to formula 1. For example, V in formula 1 inrms 2 Change to V inrms , or at V inrms 2 Before increasing the adjustment coefficient, or V inrms 2 Change to V in 2 , or V ref 2 Various modifications such as changing to other values ​​are within the protection scope of this application.

[0064] like Figure 4 As shown, after calculating the load current feed-forward coefficient, the inductor current signal is collected to calculate the duty cycle of the switch drive signal. In one embodiment, the step S200: calculating the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal includes:

[0065] Based on the function D = f1(I L R s ,K o I o ,V m ) calculates the duty cycle of the switch drive signal; where D is the duty cycle of the switch drive signal, I L is the inductor current signal, R s is the resistance of the current sampling resistor, K o is the load current feed-forward coefficient, I o is the output current signal, V m is the voltage control signal, and the function f1 satisfies: I L R s K has an inverse growth relationship with D. o I o V has the same growth relationship with D. m It has the same growth direction as d.

[0066] Function f1(I L R s ,K o I o ,V m ) For example, it can be in the form of the following formula 2:

[0067]

[0068] The form of the above formula 2 is only an example. In other implementations, the function f1 may also adopt other forms as long as it can satisfy the variation relationship between various signals, and various variations are within the protection scope of the present application.

[0069] In another embodiment, the value of the function f1 can be used as the first component of the duty cycle, and the duty cycle can also include a duty cycle increment ΔD as a second component, and the duty cycle increment ΔD is determined by the working state of the equipment (such as welding state). Figure 5 Schematic diagram of a duty cycle calculation process according to an embodiment of the present application. Figure 6 FIG. 1 is a flow chart of a duty cycle control circuit according to an embodiment of the present application. Figure 5 and Figure 6 It can be seen that the voltage control signal V is calculated by the PI control algorithm. m After that, OCC (One-Cycle Control) calculation is performed, and the above function f1 is used to calculate and obtain the first component of the duty cycle, and then the duty cycle increment ΔD is added on the basis of the first component to obtain the duty cycle used for PWM modulation. This application can accurately control the on and off time of the switching device through the digital single-cycle control adaptive algorithm of the power factor correction circuit, significantly improve the power factor of the power supply system, reduce the reactive power loss at the power supply end, and ensure that the driven equipment can provide stable and efficient power output under various working conditions. This method has high anti-interference ability and adaptability, can cope with complex power supply end environment and variable load requirements, and provide strong guarantee for the stable operation of the driven equipment.

[0070] In this implementation, the step S200: calculating the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, includes:

[0071] Obtaining a duty cycle increment ΔD; wherein the duty cycle increment and the output voltage signal of the power factor correction circuit are in an inverse growth relationship; the duty cycle increment ΔD is determined by the working state of the driven device. Taking welding equipment as an example, during short-circuit welding, a sudden increase in power generally occurs when the welding wire contacts the workpiece and a short circuit occurs. At this time, the output voltage is more likely to drop. Since the duty cycle increment and the output voltage signal are in an inverse growth relationship, the duty cycle increment will increase. Adding a certain duty cycle increment to the duty cycle will further increase the duty cycle, rapidly increase the output voltage, and improve the output voltage control response speed;

[0072] Based on the function D = f1(I L R s ,K o I o ,V m)+ΔD to calculate the duty cycle of the switch drive signal; where D is the duty cycle of the switch drive signal, I L is the inductor current signal, R s is the resistance of the current sampling resistor, K o is the load current feed-forward coefficient, I o is the output current signal, V m is the voltage control signal, and the function f1 satisfies: I L R s K has an inverse growth relationship with D. o I o V has the same growth relationship with D. m It has the same growth relationship with D.

[0073] like Figure 6 As shown, in the calculation of the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, based on f1(I L R s ,K o I o ,V m ) After performing OCC calculation to obtain the first component of the duty cycle, the duty cycle increment ΔD is obtained by the following steps:

[0074] Determine whether an output circuit is short-circuited, where the output circuit is a circuit for a driven device to output voltage to perform a corresponding work, such as a welding circuit of a welding device;

[0075] Among them, judging whether the output circuit is short-circuited can be obtained by sampling and comparing the output voltage of the driven device. When the output voltage of the device is less than the preset minimum voltage threshold, it is determined that the output circuit is short-circuited, otherwise it is considered that the output circuit is not short-circuited. The comparison is realized by a comparator, and the comparison result signal output by the comparator is input into the single-chip microcomputer of the control system after being isolated by an optical coupler and a clock interrupt is generated in the digital control to trigger the operation of adding the duty cycle increment to the duty cycle, so as to quickly compensate for the output voltage drop during the short circuit and maintain the stability of the welding process.

[0076] If no short circuit occurs, there is no need to increase the duty cycle increment, and ΔD is set to a preset minimum value, such as 0, and the duty cycle is equal to the function f1(I L R s ,K o I o ,V m ) calculated, that is, D = f1(I L R s ,K o I o ,V m );

[0077] If a short circuit occurs, the duty cycle increment is determined according to the output voltage signal of the power factor correction circuit. In this embodiment, the duty cycle increment is calculated using the following formula:

[0078] ΔD=m*(N ref -V o )

[0079] Where m is the preset response coefficient, V ref is the preset voltage reference value, V o is the output voltage signal of the power factor correction circuit. The value of m can be set to a value between 0 and 1 as required, and by adjusting the value of m, the duty cycle increment is controlled within 20%, and the duty cycle value after the first component of the duty cycle and the duty cycle increment are added is less than 1.

[0080] like Figure 6 As shown, after calculating the duty cycle of the switch drive signal in step S200, it is determined whether the protection signal of the driven device (such as the short circuit protection signal, temperature protection signal and other fault protection signals of the driven device) is triggered. If not, the PWM signal is modulated based on the duty cycle, and the two switch drive signals of the two switch devices are processed in an interlaced half cycle, and the on and off of the two switch devices in the power factor correction circuit are controlled based on the two switch drive signals. It is determined whether the shutdown signal is triggered. If so, the driven device is turned off. If the shutdown signal is not triggered, it returns to Figure 4 The step of collecting the output voltage signal in the next cycle continues with the signal collection and duty cycle calculation. If the protection signal is triggered, the duty cycle is reset to zero and the control system enters the protection mode (such as shutting down the output, issuing an alarm, and recording faults).

[0081] like Figure 7 As shown, the embodiment of the present application also provides a power factor correction circuit load feedforward control system, which is applied to a power factor correction circuit load feedforward control method, and the system includes:

[0082] The signal acquisition module M100 is used to obtain the voltage control signal of the power factor correction circuit, collect the output current signal of the power factor correction circuit, and collect the inductor current signal of the power factor correction circuit;

[0083] The duty cycle calculation module M200 is used to calculate the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, wherein the voltage control signal and the duty cycle are in a same-direction growth relationship, the output current signal and the duty cycle are in a same-direction growth relationship, and the inductor current signal and the duty cycle are in a reverse growth relationship;

[0084] The circuit control module M300 is used to control the on and off of the switch device of the power factor correction circuit according to the duty cycle of the switch drive signal.

[0085] The functions of each module in the power factor correction circuit load feedforward control system can be implemented by adopting the specific implementation methods of each step in the above-mentioned power factor correction circuit load feedforward control method, which will not be described in detail here.

[0086] By adopting the load feedforward control system of the power factor correction circuit of the present application, the duty cycle of the switch drive signal of the power factor correction circuit can be adaptively adjusted according to the output current signal, and the influence of the load change on the output voltage can be predicted and compensated to achieve fast, stable and accurate voltage control, which is suitable for power supply scenarios with large load changes and high dynamic characteristics such as welding equipment. Taking the driven device as a welding device as an example, when the output end of the welding device is loaded instantly, the output voltage of the welding device will drop instantly, and the output current will increase. Since the voltage control signal and the duty cycle are in the same direction of growth, the difference between the output voltage and the preset reference voltage increases, which will increase the voltage control signal, thereby increasing the duty cycle under the influence of the voltage control signal, and the output current signal and the duty cycle are in the same direction of growth. Under the influence of the output current signal, the duty cycle is further increased, and the change of the output voltage can be quickly compensated, thereby maintaining the stability of welding and improving the welding quality. Therefore, the present application realizes the stable output and accurate control of the welding power supply by accurately predicting and compensating for load changes, which provides strong support for the optimization of the welding process.

[0087] The above content is a further detailed description of the present application in combination with specific preferred implementation methods, and it cannot be determined that the specific implementation of the present application is limited to these descriptions. For ordinary technicians in the technical field to which the present application belongs, several simple deductions or substitutions can be made without departing from the concept of the present application, which should be deemed to fall within the scope of protection of the present application.

Claims

1. A load feedforward control method for a power factor correction circuit, characterized in that: include: Acquiring a voltage control signal of the power factor correction circuit, collecting an output current signal of the power factor correction circuit, and collecting an inductor current signal of the power factor correction circuit; Calculating the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, wherein the voltage control signal and the duty cycle are in a same-direction growth relationship, the output current signal and the duty cycle are in a same-direction growth relationship, and the inductor current signal and the duty cycle are in a reverse-direction growth relationship; The on-off of the switch device of the power factor correction circuit is controlled according to the duty cycle of the switch drive signal.

2. The load feedforward control method of a power factor correction circuit according to claim 1, characterized in that: Calculating a duty cycle of a switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal, and the inductor current signal, comprising: Based on the function D = f1(I L R s ,K o I o ,V m ) calculates the duty cycle of the switch drive signal; wherein D is the duty cycle of the switch drive signal, I L is the inductor current signal, R s is the resistance of the current sampling resistor, K o is the load current feed-forward coefficient, I o is the output current signal, V m is the voltage control signal, and the function f1 satisfies: I L R s K has an inverse growth relationship with D. o I o V has the same growth relationship with D. m It has the same growth relationship with D.

3. The load feedforward control method of a power factor correction circuit according to claim 1, characterized in that: Calculating a duty cycle of a switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal, and the inductor current signal, comprising: Obtaining a duty cycle increment ΔD; wherein the duty cycle increment and the output voltage signal of the power factor correction circuit are in an inverse growth relationship; Based on the function D = f1(I L R s ,K o I o ,V m )+ΔD to calculate the duty cycle of the switch drive signal; wherein D is the duty cycle of the switch drive signal, I L is the inductor current signal, R s is the resistance of the current sampling resistor, K o is the load current feed-forward coefficient, I o is the output current signal, V m is the voltage control signal, and the function f1 satisfies: I L R s K has an inverse growth relationship with D. o I o V has the same growth relationship with D. m It has the same growth relationship with D.

4. The load feedforward control method of a power factor correction circuit according to claim 3, characterized in that: The duty cycle increment is calculated using the following formula: ΔD=m*(N ref -V o ) Where m is the preset response coefficient, V ref is the preset voltage reference value, V o is the output voltage signal of the power factor correction circuit.

5. The load feedforward control method of a power factor correction circuit according to claim 3, characterized in that: In calculating the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, before obtaining the duty cycle increment ΔD, the following steps are also included: Determine whether the output circuit is short-circuited; If not, ΔD is set to a preset minimum value; If so, the output voltage signal of the power factor correction circuit determines the duty cycle increment.

6. The load feedforward control method for a power factor correction circuit according to any one of claims 2 to 5, characterized in that: Before calculating the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, the following steps are also included: Collecting an input voltage signal of the power factor correction circuit; The load current feed-forward coefficient is calculated according to the input voltage signal.

7. The load feedforward control method of a power factor correction circuit according to claim 6, characterized in that: Calculating the load current feedforward coefficient according to the input voltage signal comprises the following steps: Calculating a root mean square value of the input voltage signal; Based on the function K o =f2(V inrms ) calculating the load current feed-forward coefficient; Among them, V inrms is the RMS value of the input voltage signal, and function f2 satisfies: V inrms With K o It is a reverse growth relationship.

8. The load feedforward control method of a power factor correction circuit according to claim 1, characterized in that: Obtaining the voltage control signal of the power factor correction circuit comprises the following steps: Collecting an output voltage signal of the power factor correction circuit; A voltage control signal is obtained based on a preset voltage control algorithm according to the output voltage signal and a preset reference voltage.

9. The load feedforward control method of a power factor correction circuit according to claim 8, characterized in that: The preset voltage control algorithm is a proportional-integral control algorithm, wherein the difference between the output voltage signal and the preset reference voltage is taken as an error.

10. A power factor correction circuit load feedforward control system, characterized in that: A load feedforward control method for a power factor correction circuit according to any one of claims 1 to 9, the system comprising: A signal acquisition module, used to acquire a voltage control signal of the power factor correction circuit, acquire an output current signal of the power factor correction circuit, and acquire an inductor current signal of the power factor correction circuit; a duty cycle calculation module, configured to calculate the duty cycle of the switch drive signal of the power factor correction circuit based on the voltage control signal, the output current signal and the inductor current signal, wherein the voltage control signal and the duty cycle are in a same-direction growth relationship, the output current signal and the duty cycle are in a same-direction growth relationship, and the inductor current signal and the duty cycle are in a reverse-direction growth relationship; A circuit control module is used to control the on and off of the switch device of the power factor correction circuit according to the duty cycle of the switch drive signal.

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