Model prediction control method and system for totem pole PFC circuit

Abstract

The invention discloses a model prediction control method and system for a totem-pole PFC circuit, and belongs to the technical field of totem-pole PFC circuits, and the method comprises the steps: monitoring the input voltage of an AC power supply, the bus voltage of the totem-pole PFC circuit, and load demand information in real time; determining that the totem-pole PFC circuit works in a boost mode or a voltage-multiplying mode and driving signal distribution logic of each switch tube in the bridge circuit; calculating an optimal modulation ratio based on a model prediction control algorithm according to an error between the target bus voltage and the currently detected bus voltage; generating a first SPWM signal with a corresponding duty ratio and a complementary second SPWM signal according to the optimal modulation ratio; and distributing the first SPWM signal and the second SPWM signal to corresponding switch tubes to realize control of the bus voltage. According to the method, the SPWM duty ratio is dynamically adjusted through model prediction control, and rapid, accurate and stable control over the totem pole PFC bus voltage is achieved.

Description

A Model Predictive Control Method and System for a Totem PFC Circuit Technical Field

[0001] This invention belongs to the field of totem pole PFC circuit technology, and more specifically, relates to a model predictive control method and system for totem pole PFC circuits. Background Technology

[0002] Totem-pole PFC is an effective circuit for improving power factor. Adding a switching device K to the totem-pole PFC circuit can achieve a voltage multiplier effect. By controlling the switching devices MOSFET and K according to the bus voltage requirements, the bus voltage can be boosted, multiplied, or bucked.

[0003] In the existing technology, there are totem-pole PFC control methods that adjust the switching transistor, switching module, or number of charge and discharge cycles based on load, input voltage, and bus voltage. However, they all have problems such as the inability to dynamically adjust the charging and discharging time and ratio in real time, low control flexibility, and slow bus voltage response speed, making it difficult to achieve fast and accurate tracking of the reference voltage. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a model predictive control method and system for totem pole PFC circuits.

[0005] The present invention adopts the following technical solution.

[0006] A first aspect of the present invention provides a model predictive control method for a totem-pole PFC circuit. The totem-pole PFC circuit includes an AC power supply, an inductor, a bridge circuit composed of four switching transistors, a switching module, and a bus inductor. The method includes: real-time monitoring of the input voltage of the AC power supply, the bus voltage of the totem-pole PFC circuit, and load demand information; determining and controlling the on / off state of the switching module based on the load demand information and the input voltage to determine whether the totem-pole PFC circuit operates in boost mode or voltage multiplier mode; and determining the phase of the input voltage and the determined operating mode. The drive signal allocation logic for each switch in the bridge circuit is as follows: Based on the error between the target bus voltage and the currently detected bus voltage, the optimal modulation ratio for controlling the rate of change of the bus voltage is calculated using a model predictive control algorithm; Based on the optimal modulation ratio, a first SPWM signal with a corresponding duty cycle and a complementary second SPWM signal are generated; According to the drive signal allocation logic, the first SPWM signal and the second SPWM signal are allocated to the corresponding switch to adjust the charging and discharging duration ratio of the totem-pole PFC circuit in one switching cycle, thereby controlling the bus voltage.

[0007] Optionally, determining and controlling the switching module includes: when the demand voltage corresponding to the load demand information is less than a preset voltage threshold, controlling the switching module to open, so that the totem pole PFC circuit operates in boost mode; when the demand voltage corresponding to the load demand information is greater than or equal to the preset voltage threshold, controlling the switching module to close, so that the totem pole PFC circuit operates in voltage multiplication mode.

[0008] Optionally, the bridge circuit includes a first bridge arm composed of a first switch and a second switch connected in series, and a second bridge arm composed of a third switch and a fourth switch connected in series. The logic for determining the drive signal allocation for each switch in the bridge circuit includes: in boost mode, controlling the switching module to disconnect; wherein, during the positive half-cycle of the input current, controlling the third switch to turn off and the fourth switch to turn on, and allocating the first SPWM signal to the first switch and the second SPWM signal as its complementary signal to the second switch; wherein, during the negative half-cycle of the input current, controlling the third switch to turn on, The fourth switch is turned off, and the first SPWM signal is allocated to the first switch, and the second SPWM signal is allocated to the second switch as its complementary signal; in voltage doubling mode, the switching module is controlled to close; wherein, during the positive half-cycle of the input current, the first switch is controlled to turn on, the second switch and the fourth switch are turned off, and the second SPWM signal is allocated to the third switch; wherein, during the negative half-cycle of the input current, the second switch is controlled to turn on, the first switch and the turned-on third switch are turned off, and the first SPWM signal is allocated to the fourth switch.

[0009] Optionally, the optimal modulation ratio for controlling the rate of change of the bus voltage, calculated using the model predictive control algorithm, includes: establishing a discrete state prediction model based on the physical relationship between the totem-pole PFC circuit during the charging and discharging phases. The input of the discrete state prediction model is the current bus voltage, inductor current, and SPWM modulation ratio, and the output is the predicted bus voltage for future times. At the current sampling time, with the optimization objective of minimizing the error between the predicted bus voltage and the target bus voltage while suppressing modulation ratio fluctuations, a rolling optimization solution is performed to obtain the future control sequence that minimizes the objective function value. The first control variable in this future control sequence is taken as the optimal modulation ratio at the current time. At the next sampling time, the output of the discrete state prediction model is corrected by feedback using the actually detected bus voltage, and the above steps are repeated to achieve closed-loop optimization control.

[0010] Optionally, generating a first SPWM signal with a corresponding duty cycle and a complementary second SPWM signal includes: using the optimal modulation ratio as the amplitude ratio of the sinusoidal modulation wave relative to the triangular carrier wave, and adjusting the amplitude of the sinusoidal modulation wave accordingly; comparing the amplitude-adjusted sinusoidal modulation wave with a triangular carrier wave of fixed amplitude to generate the first SPWM signal; and inverting the first SPWM signal to generate the complementary second SPWM signal.

[0011] Optionally, adjusting the charging and discharging duration ratio of the totem-pole PFC circuit within one switching cycle includes: adjusting the duty cycle of the first SPWM signal and simultaneously changing the duty cycle of the second SPWM signal; within one switching cycle, when the first SPWM signal is at an active level, controlling the corresponding switch to turn on so that the totem-pole PFC circuit is in the discharging phase, and the bus voltage decreases; when the second SPWM signal is at an active level, controlling the corresponding switch to turn on so that the totem-pole PFC circuit is in the charging phase, and the bus voltage increases; by changing the duty cycles of the first SPWM and the second SPWM signals, dynamically adjusting the duration ratio of the charging phase and the discharging phase within one switching cycle, thereby controlling the trend of bus voltage change.

[0012] A second aspect of this invention provides a model predictive control system for a totem-pole PFC circuit, used to implement the model predictive control method for a totem-pole PFC circuit described in the first aspect of this invention. The system includes: an AC voltage detection module, a DC voltage detection module, a load detection module, and a controller. The AC voltage detection module detects the input voltage of an AC power supply; the DC voltage detection module detects the bus voltage of the totem-pole PFC circuit; the load detection module detects load demand information; and the controller is connected to the AC voltage detection module, the DC voltage detection module, the load detection module, and the totem-pole PFC circuit, respectively, and is used to execute the model predictive control method for a totem-pole PFC circuit described in the first aspect of this invention to generate control signals to drive the switching transistors and switching modules in the totem-pole PFC circuit.

[0013] A third aspect of the present invention provides a totem pole PFC circuit, comprising a model prediction control system of the totem pole PFC circuit described in the second aspect of the present invention.

[0014] A fourth aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the computer program is loaded onto the processor, it implements a model predictive control method for a totem pole PFC circuit according to a first aspect of the present invention.

[0015] The fifth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements a model predictive control method for a totem pole PFC circuit according to the first aspect of the present invention.

[0016] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1. The present invention solves the problems of slow response and low accuracy of totem pole PFC bus voltage control by real-time monitoring of input voltage, bus voltage and load demand information, combined with model predictive control algorithm to dynamically adjust SPWM duty cycle, thereby achieving fast, accurate and stable control of bus voltage.

[0017] 2. This invention controls the switching module to turn on and off by comparing the load demand voltage with a preset threshold, which solves the problem of unintelligent switching of traditional circuit working modes, realizes automatic and accurate switching between boost mode and voltage multiplier mode, and improves system efficiency.

[0018] 3. This invention solves the problems of complex and error-prone switching control strategies by setting clear drive signal allocation logic for the four switching transistors under different operating modes and input voltage phases, and realizes balanced use of switching transistors and reliable system operation.

[0019] 4. By establishing a discrete state prediction model and performing rolling optimization and feedback correction, this invention solves the problems of lag and overshoot in bus voltage control, and realizes accurate prediction and closed-loop optimization control of voltage change trends.

[0020] 5. This invention solves the problem of complex and indirect control signal generation by directly converting the optimal modulation ratio into the amplitude of a sinusoidal modulation wave to generate an SPWM signal, and realizes a fast and accurate mapping from modulation ratio to duty cycle.

[0021] 6. This invention dynamically changes the charging and discharging duration ratio within a switching cycle by adjusting the duty cycle of a pair of complementary SPWM signals, solving the problem of the inflexible adjustment of the bus voltage change rate and realizing precise control of the voltage rise and fall speed.

[0022] 7. By constructing a hardware system that includes a detection module and a controller, this invention solves the problem that traditional methods are difficult to implement model predictive control algorithms at the physical level, and provides a reliable and efficient hardware platform for the practical application of the method.

[0023] 8. By integrating the model predictive control system into the totem pole PFC circuit, this invention solves the problem of limited control performance of traditional PFC circuits and provides a high-performance PFC circuit topology that combines high power factor and fast dynamic response capability.

[0024] 9. The present invention implements the control method by running a computer program on the processor of an electronic device, which solves the problems of high cost and poor flexibility of dedicated controllers, realizes high-performance PFC control on a general computing platform, and reduces implementation costs.

[0025] 10. By storing the control method in a computer-readable storage medium, the present invention solves the problems of inconvenient solidification and difficult upgrading of control algorithms, realizes convenient storage, distribution and updating of control programs, and improves the maintainability and adaptability of the system. Attached Figure Description

[0026] Figure 1 is a circuit diagram, peripheral detection components, and controller schematic diagram of a totem-pole PFC provided according to an embodiment of the present invention; Figure 2 is a control block diagram of a totem-pole PFC provided according to an embodiment of the present invention; Figure 3 is a logic judgment flowchart in the controller provided according to an embodiment of the present invention; Figure 4 is a detailed block diagram of model predictive control provided according to an embodiment of the present invention; Figure 5 is a schematic diagram of carrier waveforms and modulation waveforms corresponding to different modulation ratios and the generated SPWM and complementary SPWM provided according to an embodiment of the present invention; Figure 6 is a schematic diagram of inductor current and bus voltage obtained by SPWM and complementary SPWM with different duty cycles provided according to an embodiment of the present invention; Figure 7 is a method flowchart provided according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0028] In Embodiment 1, the present invention provides a model predictive control method for a totem pole PFC circuit. The totem pole PFC circuit includes an AC power supply, an inductor, a bridge circuit composed of four switching transistors, a switching module, and a bus capacitor, as shown in Figure 7. The method includes the following steps: Step 1, real-time monitoring of the input voltage of the AC power supply, the bus voltage of the totem pole PFC circuit, and load demand information.

[0029] Step 2: Based on the load demand information and the input voltage, determine and control the on / off state of the switching module to determine whether the totem pole PFC circuit is operating in boost mode or voltage multiplier mode; and based on the phase of the input voltage and the determined operating mode, determine the drive signal allocation logic for each switching transistor in the bridge circuit.

[0030] Preferably, the determination and control of the switching module's on / off state includes: when the demand voltage corresponding to the load demand information is less than a preset voltage threshold, controlling the switching module to open, so that the totem pole PFC circuit operates in boost mode; when the demand voltage corresponding to the load demand information is greater than or equal to the preset voltage threshold, controlling the switching module to close, so that the totem pole PFC circuit operates in voltage multiplication mode.

[0031] For example, the preset voltage threshold is twice the peak voltage of the AC power supply.

[0032] Preferably, the bridge circuit includes a first bridge arm composed of a first switch and a second switch connected in series, and a second bridge arm composed of a third switch and a fourth switch connected in series. The logic for determining the drive signal allocation for each switch in the bridge circuit includes: in boost mode, controlling the switching module to disconnect; wherein, during the positive half-cycle of the input current, controlling the third switch to turn off and the fourth switch to turn on, and allocating the first SPWM signal to the first switch and the second SPWM signal as its complementary signal to the second switch; wherein, during the negative half-cycle of the input current, controlling the third switch to turn on, The fourth switch is turned off, and the first SPWM signal is allocated to the first switch, and the second SPWM signal is allocated to the second switch as its complementary signal; in voltage doubling mode, the switching module is controlled to close; wherein, during the positive half-cycle of the input current, the first switch is controlled to turn on, the second switch and the fourth switch are turned off, and the second SPWM signal is allocated to the third switch; wherein, during the negative half-cycle of the input current, the second switch is controlled to turn on, the first switch and the turned-on third switch are turned off, and the first SPWM signal is allocated to the fourth switch.

[0033] It should be noted that this invention intelligently controls the working mode by comparing the load demand with a preset threshold, and solves the problem of complex coupling between mode switching and switching control by accurately allocating the switching transistor drive logic through the input voltage phase, thus achieving efficient and reliable operation of the system.

[0034] Step 3: Based on the error between the target bus voltage and the currently detected bus voltage, calculate the optimal modulation ratio for controlling the rate of change of the bus voltage using the model predictive control algorithm.

[0035] Preferably, the optimal modulation ratio for controlling the rate of change of the bus voltage, calculated using the model predictive control algorithm, includes: establishing a discrete state prediction model based on the physical relationship between the totem-pole PFC circuit during the charging and discharging phases; the input of the discrete state prediction model is the current bus voltage, inductor current, and SPWM modulation ratio, and the output is the predicted bus voltage for future times; at the current sampling time, with the optimization objective of minimizing the error between the predicted bus voltage and the target bus voltage while suppressing modulation ratio fluctuations, a rolling optimization solution is performed to obtain the future control sequence that minimizes the objective function value, and the first control quantity in the future control sequence is taken as the optimal modulation ratio at the current time; at the next sampling time, the output of the discrete state prediction model is corrected by feedback using the actually detected bus voltage, and the above steps are repeated to achieve closed-loop optimization control.

[0036] It should be noted that this invention solves the problems of slow dynamic response and poor disturbance rejection of traditional PI control by establishing a discrete prediction model and performing rolling optimization and feedback correction, and realizes fast and zero steady-state error tracking of bus voltage.

[0037] Step 4: Based on the optimal modulation ratio, generate a first SPWM signal with a corresponding duty cycle and a complementary second SPWM signal.

[0038] Preferably, generating a first SPWM signal with a corresponding duty cycle and a complementary second SPWM signal includes: using the optimal modulation ratio as the amplitude ratio of the sinusoidal modulation wave relative to the triangular carrier wave, and adjusting the amplitude of the sinusoidal modulation wave accordingly; comparing the amplitude-adjusted sinusoidal modulation wave with a triangular carrier wave of fixed amplitude to generate the first SPWM signal; and inverting the first SPWM signal to generate the complementary second SPWM signal.

[0039] Step 5: According to the drive signal allocation logic, the first SPWM signal and the second SPWM signal are allocated to the corresponding switching transistors to adjust the charging and discharging duration ratio of the totem pole PFC circuit in one switching cycle, thereby controlling the bus voltage.

[0040] Preferably, adjusting the charging and discharging duration ratio of the totem-pole PFC circuit within one switching cycle includes: adjusting the duty cycle of the first SPWM signal and simultaneously changing the duty cycle of the second SPWM signal; within one switching cycle, when the first SPWM signal is at an active level, controlling the corresponding switch to turn on so that the totem-pole PFC circuit is in the discharging phase, and the bus voltage decreases; when the second SPWM signal is at an active level, controlling the corresponding switch to turn on so that the totem-pole PFC circuit is in the charging phase, and the bus voltage increases; by changing the duty cycles of the first SPWM and the second SPWM signals, the duration ratio of the charging phase and the discharging phase within one switching cycle is dynamically adjusted, thereby controlling the trend of bus voltage change.

[0041] It should be noted that this invention controls the charging and discharging duration by dynamically adjusting the duty cycle of the complementary SPWM, which solves the problem of fixed voltage regulation rate and realizes flexible control of the bus voltage change rate, thereby improving the dynamic performance of the system.

[0042] In Embodiment 2, this invention provides a model predictive control system for a totem-pole PFC circuit, used to implement the model predictive control method for a totem-pole PFC circuit described in Embodiment 1. The system includes: an AC voltage detection module, a DC voltage detection module, a load detection module, and a controller. The AC voltage detection module detects the input voltage of the AC power supply; the DC voltage detection module detects the bus voltage of the totem-pole PFC circuit; the load detection module detects load demand information; and the controller is connected to the AC voltage detection module, the DC voltage detection module, the load detection module, and the totem-pole PFC circuit, respectively, and executes the steps of the method described in Embodiment 1 to generate control signals to drive the switching transistors and the switching module.

[0043] It should be noted that this invention integrates AC voltage, DC voltage, and load detection modules, and works in conjunction with the controller to construct a complete model predictive control hardware system. This solves the problem of advanced algorithms lacking a physical carrier and lays the foundation for the engineering application of the method.

[0044] In Embodiment 3, the present invention provides a totem pole PFC circuit, which includes a model prediction control system based on the totem pole PFC circuit described in Embodiment 2.

[0045] It should be noted that by embedding the control system into the totem pole PFC circuit, the present invention provides a novel PFC circuit device, which solves the problem of the bottleneck of traditional circuit control performance, and makes the circuit have both high efficiency and high dynamic performance.

[0046] Embodiment 4 of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is loaded onto the processor, it implements a model predictive control method for a totem pole PFC circuit according to Embodiment 1.

[0047] Embodiment 5 of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements a model predictive control method for a totem pole PFC circuit according to Embodiment 1.

[0048] Embodiment 6 of the present invention provides an application example of a model predictive control method for a totem pole PFC circuit. As shown in Figure 1, the totem pole PFC circuit consists of an AC power supply AC, an inductor L, a bridge circuit, a switching module K, and a bus capacitor. In addition, it also includes an input voltage detection module, a bus voltage detection module, a load detection module, and a controller.

[0049] The first switch Q1 and the second switch Q2 are connected in series to form one bridge arm, with their midpoint connected to one end of the AC power supply via inductor L. The third switch Q3 and the fourth switch Q4 are connected in series to form another bridge arm, with their midpoint connected to the other end of the AC power supply. Each switch is connected in anti-parallel to a diode for freewheeling. Furthermore, the first capacitor C1 and the second capacitor C2 are connected in series to form a bus capacitor C, which is connected in parallel to the bridge output. The midpoint of the two capacitors is connected to the midpoint of the third switch Q3 and the fourth switch Q4 via a switching module K. The boost and voltage multiplier modes can be switched by controlling the switching module K.

[0050] The input voltage detection module, bus voltage detection module, and load detection module feed back the measured input voltage, bus voltage, and load to the controller. The controller calculates SPWM pulses with different duty cycles and controls the on / off state of the four MOSFETs and the switching component K, thereby controlling the bus voltage. The bus voltage acts on the inverter module downstream to obtain an AC signal, which drives the compressor to work.

[0051] In a totem pole PFC circuit, controlling the on / off state of the switch component K can control the circuit to operate in boost or voltage multiplication mode, and controlling the on / off state of the four switching devices MOSFET can realize the charging or discharging of the bus voltage.

[0052] Specifically, the switching component K is controlled to open and close according to the load. When the required voltage is less than twice the peak voltage of the AC power supply, the switching module is controlled to open and operate in boost mode; when the required voltage is greater than or equal to twice the peak voltage of the AC power supply, the switching module is controlled to close and operate in voltage multiplication mode.

[0053] The detailed control block diagram of the controller is shown in Figure 2. It includes logic judgment and model predictive control. The input voltage and load are used as inputs for logic judgment. The state of switch K is determined by comparing the load with twice the peak value of the input AC voltage. The state of the four MOSFETs is further determined by the phase of the input voltage and the state of switch K. The error value between the required voltage and the current bus voltage is used as input for model predictive control. Model predictive control can calculate two complementary SPWM waves and distribute these two SPWM waves to the appropriate MOSFETs in combination with logic judgment.

[0054] The judgment process of the logic judgment part in the controller is shown in Figure 3, including: First, controlling the on / off state of the switch module K according to the load demand: when the demand voltage is greater than twice the peak voltage of the AC power supply, the switch module K is controlled to close, so that the circuit works in voltage doubling mode; when the demand voltage is less than or equal to twice the peak voltage of the AC power supply, the switch module K is controlled to open, so that the circuit works in voltage boost mode.

[0055] Next, based on whether the totem-pole PFC circuit is operating in boost mode or voltage multiplier mode, and combined with the phase of the input voltage, the state of the first switch Q1 to the fourth switch Q4 is further determined.

[0056] To balance the switching losses of each switch, in boost mode, the first switch Q1 and the second switch Q2 act as master switches, driven by two complementary SPWM signals; the third switch Q3 and the fourth switch Q4 act as slave switches, changing their switching state only when the positive and negative half-cycles of the input current switch.

[0057] In voltage multiplier mode, the third switch Q3 and the fourth switch Q4 act as master switches, driven by two complementary SPWM signals; the first switch Q1 and the second switch Q2 act as slave switches, changing their switching state only when the positive and negative half-cycles of the input current switch. The states of each switch and the switching module, determined by the boost or voltage multiplier state and the phase of the input voltage, are summarized in Table 1.

[0058] In boost mode, switch module K is off. During the positive half-cycle of the input current, the third switch Q3 is off, the fourth switch Q4 is on, and the first switch Q1 receives the SPWM signal, while the second switch Q2 receives its complementary SPWM signal. During the negative half-cycle of the input current, the third switch Q3 is on, the fourth switch Q4 is off, the first switch Q1 receives the SPWM signal, and the second switch Q2 receives its complementary SPWM signal.

[0059] In voltage multiplier mode, switch module K is closed. During the positive half-cycle of the input current, the first switch Q1 is closed, the second switch Q2 and the fourth switch Q4 are turned off, and the third switch Q3 receives a complementary SPWM signal; during the negative half-cycle of the input current, the second switch Q2 is closed, the first switch Q1 and the third switch Q3 are turned off, and the fourth switch Q4 receives the SPWM signal.

[0060] The SPWM signals received by the first switch Q1 to the fourth switch Q4 are generated by comparing a triangular carrier signal and a sinusoidal modulation wave signal. The model predictive control method proposed in this invention can adjust the modulation ratio according to the difference between the target voltage and the actual bus voltage, thereby adjusting the duty cycle of the SPWM signal and its complementary signal, that is, adjusting the duration ratio of the charging and discharging phases within a switching cycle, and ultimately achieving precise control over the rate of change of the bus voltage.

[0061] Table 1: MOSFETs and Switches under Different States

[0062] Model predictive control (MDC) is an advanced control algorithm that predicts and implements control based on a model, following the fundamental principles of predictive models, rolling optimization, and feedback correction. The predictive model is the foundation of MDC; it predicts the future state of the controlled object by using the current system state information provided by the controlled object and the future control input variables. At each sampling time, the optimal control rate for a finite period is calculated based on the optimization performance index at that time. Only the current value of the calculated control action sequence is actually executed; the optimal control rate is recalculated at the next sampling time.

[0063] In predictive control, the measured output value is compared with the model's predicted value to determine the model's prediction error. This error is then used to correct the model's predictions, resulting in a more accurate prediction of the future output. This process of model-based feedback correction gives predictive control strong anti-interference capabilities and the ability to overcome system uncertainties. Continuously adjusting the predicted output based on the system's actual output ensures that rolling optimization is not only model-based but also utilizes feedback information to construct closed-loop optimization control.

[0064] The control block diagram of Model Predictive Control (MMDC) in a totem-pole PFC is shown in Figure 4. The MMDC internally includes a predictive model and an optimal solution unit. The inputs to the predictive model are the target voltage value, the current bus voltage value, and the current control signal. Its output is the predicted bus voltage value for the next few cycles. The predicted values ​​are then passed to the optimization algorithm, which calculates the optimal control signal, i.e., the modulation ratio, and transmits it to the SPWM generator. The SPWM generator adjusts the amplitude ratio of the triangular carrier wave and the sinusoidal modulation wave according to the modulation ratio to obtain the optimal SPWM waveform, which is then transmitted to the MOSFET of the totem-pole PFC circuit, achieving precise and rapid control of the bus voltage.

[0065] Based on the physical model of the totem pole PFC circuit, the physical model of the totem pole PFC circuit during the discharge phase is as follows:

[0066] During the charging phase, the physical model of the totem pole PFC circuit is as follows:

[0067] Where R, L, and C are the load resistance, charging inductance, and bus capacitance, respectively. , and These are the input voltage, output voltage, and inductor current, respectively.

[0068] Based on the modulation ratio of the SPWM signal The average of the charging and discharging states is then linearized and expanded near the operating point to obtain:

[0069] in, The modulation ratio of the SPWM signal. , and These are the bus voltage, inductor current, and SPWM modulation ratio at the steady-state operating point, respectively.

[0070] Discretizing it yields:

[0071] in, For discretized periods, , and These represent the inductor current, bus voltage, and SPWM modulation ratio at the current moment, respectively. , and These represent the inductor current, bus voltage, and SPWM modulation ratio at the next moment, respectively.

[0072] This prediction model can be based on the modulation ratio at the current time. The inherent parameters of the circuit, R, L, C, and the parameters of the steady-state operating point. , and Discretized period and the inductor current at the previous moment With bus voltage To predict the inductor current at the next moment With bus voltage and control parameters and bus voltage and The cost function is input into the optimal solution unit to make the cost function Minimum.

[0073] The optimization objective of the optimal solution unit is to minimize the error between the predicted voltage and the reference voltage, and to minimize the change in the modulation ratio. Its cost function is:

[0074] in, For the bus voltage at the next moment, The reference voltage is the target value of the bus voltage. The modulation ratio at the current moment, This represents the modulation ratio at the previous time step. The goal of this optimization algorithm is to find a modulation ratio that makes... Minimum modulation ratio This ensures a fast voltage response and a small rate of change in the modulation ratio, thereby improving system stability.

[0075] Based on the modulation ratio calculated by model predictive control, the amplitude of the sinusoidal modulation wave relative to the triangular carrier wave is adjusted, and SPWM pulses with different duty cycles and their complementary SPWM pulses can be obtained through the SPWM generator.

[0076] Taking boost mode and the positive half-cycle of the input current as an example, the third switch Q3 is off, the switching module K is open, and the fourth switch Q4 is closed. The first switch Q1 and the second switch Q2 are driven by complementary SPWM signals. When the second switch Q2 and the fourth switch Q4 are closed simultaneously, the inductor L charges, and the bus voltage increases. When the first switch Q1 and the fourth switch Q4 are closed simultaneously, the inductor L discharges to the bus, and the bus voltage decreases. Therefore, by adjusting the duty cycle of the SPWM signal, the duty cycle of its complementary signal can be adjusted synchronously, thereby controlling the proportion of the charging and discharging phases within a switching cycle, achieving rapid and accurate control of the rise and fall of the bus voltage.

[0077] The waveforms of SPWM and complementary SPWM corresponding to different modulation ratios are shown in Figure 5. By fixing the amplitude of the carrier wave and changing the amplitude of the modulation wave, the modulation ratio can be changed, thereby changing the duty cycle of SPWM and complementary SPWM. Taking the boost and positive half-cycle as an example, the modulation ratio of modulation wave 1 is smaller than that of modulation wave 2. Therefore, in the positive half-cycle of the input power supply, the duty cycle of generated SPWM1 is smaller, while the duty cycle of complementary SPWM1 is larger.

[0078] The inductor current and bus voltage values ​​corresponding to SPWM waves with different duty cycles are shown in Figure 6. Compared with SPWM2, SPWM1 has a larger duty cycle for charging and a smaller duty cycle for discharging, resulting in a faster rise in bus voltage. Therefore, by using model predictive control to output different modulation wave frequencies, SPWM and complementary SPWM with different duty cycles can be obtained, thereby adjusting the rise rate of bus voltage.

[0079] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A model predictive control method for a totem-pole PFC circuit, wherein the totem-pole PFC circuit includes an AC power supply, an inductor, a bridge circuit composed of four switching transistors, a switching module, and a bus inductor, characterized in that, The method includes: real-time monitoring of the input voltage of the AC power supply, the bus voltage of the totem-pole PFC circuit, and load demand information; determining and controlling the on / off state of the switching module based on the load demand information and the input voltage to determine whether the totem-pole PFC circuit operates in boost mode or voltage multiplier mode; determining the drive signal allocation logic for each switch in the bridge circuit based on the phase of the input voltage and the determined operating mode; calculating the optimal modulation ratio for controlling the rate of change of the bus voltage based on a model predictive control algorithm based on the error between the target bus voltage and the currently detected bus voltage; generating a first SPWM signal with a corresponding duty cycle and a complementary second SPWM signal based on the optimal modulation ratio; and allocating the first SPWM signal and the second SPWM signal to the corresponding switch according to the drive signal allocation logic to adjust the charging and discharging duration ratio of the totem-pole PFC circuit in one switching cycle, thereby controlling the bus voltage.

2. The model predictive control method for a totem-pole PFC circuit according to claim 1, characterized in that: The determination and control of the switching module's on / off state includes: when the demand voltage corresponding to the load demand information is less than a preset voltage threshold, controlling the switching module to open, so that the totem pole PFC circuit operates in boost mode; when the demand voltage corresponding to the load demand information is greater than or equal to the preset voltage threshold, controlling the switching module to close, so that the totem pole PFC circuit operates in voltage multiplication mode.

3. The model predictive control method for a totem-pole PFC circuit according to claim 1, characterized in that: The bridge circuit includes a first bridge arm consisting of a first switch and a second switch connected in series, and a second bridge arm consisting of a third switch and a fourth switch connected in series. The logic for determining the drive signal allocation for each switch in the bridge circuit includes: in boost mode, controlling the switching module to disconnect; wherein, during the positive half-cycle of the input current, controlling the third switch to turn off and the fourth switch to turn on, and allocating the first SPWM signal to the first switch and the second SPWM signal as its complementary signal to the second switch; wherein, during the negative half-cycle of the input current, controlling the third switch to turn on, and the... The fourth switch is turned off, and the first SPWM signal is allocated to the first switch, and the second SPWM signal is allocated to the second switch as its complementary signal; in voltage doubling mode, the switching module is controlled to close; wherein, during the positive half-cycle of the input current, the first switch is controlled to turn on, the second switch and the fourth switch are turned off, and the second SPWM signal is allocated to the third switch; wherein, during the negative half-cycle of the input current, the second switch is controlled to turn on, the first switch and the turned-on third switch are turned off, and the first SPWM signal is allocated to the fourth switch.

4. The model predictive control method for a totem pole PFC circuit according to claim 1, characterized in that: The optimal modulation ratio for controlling the rate of change of the bus voltage, calculated using the model predictive control algorithm, includes: establishing a discrete state prediction model based on the physical relationship between the totem-pole PFC circuit during the charging and discharging phases. The input of the discrete state prediction model is the current bus voltage, inductor current, and SPWM modulation ratio, and the output is the predicted bus voltage for future times. At the current sampling time, with the optimization objective of minimizing the error between the predicted bus voltage and the target bus voltage while suppressing modulation ratio fluctuations, a rolling optimization solution is performed to obtain the future control sequence that minimizes the objective function value. The first control variable in this future control sequence is taken as the optimal modulation ratio at the current time. At the next sampling time, the output of the discrete state prediction model is corrected by feedback using the actually detected bus voltage, and the above steps are repeated to achieve closed-loop optimization control.

5. The model predictive control method for a totem pole PFC circuit according to claim 1, characterized in that: The generation of a first SPWM signal with a corresponding duty cycle and a complementary second SPWM signal includes: using the optimal modulation ratio as the amplitude ratio of the sinusoidal modulation wave relative to the triangular carrier wave, and adjusting the amplitude of the sinusoidal modulation wave accordingly; comparing the sinusoidal modulation wave with the triangular carrier wave of fixed amplitude to generate the first SPWM signal; and inverting the first SPWM signal to generate the complementary second SPWM signal.

6. The model predictive control method for a totem pole PFC circuit according to claim 1, characterized in that: Adjusting the charging and discharging duration ratio of the totem-pole PFC circuit within one switching cycle includes: simultaneously changing the duty cycle of the second SPWM signal by adjusting the duty cycle of the first SPWM signal; within one switching cycle, when the first SPWM signal is at an active level, controlling the corresponding switch to turn on so that the totem-pole PFC circuit is in the discharging phase, and the bus voltage decreases; when the second SPWM signal is at an active level, controlling the corresponding switch to turn on so that the totem-pole PFC circuit is in the charging phase, and the bus voltage increases; by changing the duty cycles of the first SPWM and the second SPWM signals, the duration ratio of the charging phase and the discharging phase within one switching cycle is dynamically adjusted, thereby controlling the trend of bus voltage change.

7. A model predictive control system for a totem-pole PFC circuit, used to implement the model predictive control method for a totem-pole PFC circuit according to any one of claims 1-6, characterized in that, include: An AC voltage detection module, a DC voltage detection module, a load detection module, and a controller are provided, wherein: the AC voltage detection module is used to detect the input voltage of the AC power supply; the DC voltage detection module is used to detect the bus voltage of the totem-pole PFC circuit; the load detection module is used to detect load demand information; the controller is connected to the AC voltage detection module, the DC voltage detection module, the load detection module, and the totem-pole PFC circuit respectively, and is used to execute the model predictive control method for the totem-pole PFC circuit according to any one of claims 1-6, so as to generate control signals to drive the switching transistors and switching modules in the totem-pole PFC circuit.

8. A totem-pole PFC circuit, characterized in that, A model predictive control system comprising a totem pole PFC circuit as described in claim 7.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the computer program is loaded into the processor, it implements a model predictive control method for a totem pole PFC circuit according to any one of claims 1-6.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements a model predictive control method for a totem pole PFC circuit according to any one of claims 1-6.

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