A control method and device for a totem pole PFC converter and a totem pole PFC converter

Abstract

The present invention discloses a control method and device for a totem pole PFC converter and a totem pole PFC converter, wherein the control method includes obtaining a first voltage signal V in each working cycle. in , the second voltage signal V rms , the third voltage signal V out and the first current signal I z According to the third voltage signal V out and the preset voltage reference value V ref Get the voltage loop output voltage V comp , according to the first voltage signal V in、 The second voltage signal V rms、 Voltage loop output voltage V comp、 The first preset voltage value V o and the first current preset value I f Open the high frequency main first conduction time T on According to the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref , then according to the inductor negative current threshold I zref and the first current signal I z The present invention can solve the crossover distortion problem of the totem pole PFC converter near the zero crossing of the power frequency AC input, and simultaneously achieve ZVS in each working cycle within the full power frequency cycle range of the high frequency main tube.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy conversion, and in particular to a control method and device for a totem pole PFC converter, and the totem pole PFC converter. Background Art

[0002] With the rapid development of power electronics technology, the number of users of AC-DC converters has rapidly increased. However, most power electronic devices require rectification and conversion technology to convert AC power to DC. This results in the injection of large amounts of harmonic currents into the AC grid, impairing the power quality of the AC grid. To minimize the impact of load harmonics on the grid and other equipment, the input current harmonic content and power density of each electronic device must meet the current harmonic requirements for AC devices. Therefore, research on high-power-density PFC converter technology is of great significance.

[0003] Compared with the traditional bridge-type Boost PFC converter, the bridgeless PFC uses switches to replace the bridge arm diodes, reducing the loss of the switching devices in the conduction path, thereby improving efficiency. Among various bridgeless PFC topologies, the totem pole bridgeless PFC has become the mainstream due to its advantages such as fewer components and low common-mode noise. Figure 1 The figure shows a circuit diagram of a well-known totem pole bridgeless PFC converter, including a boost inductor L, a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4. The first and second switches Q1 and Q2 are high-frequency switches, while the third and fourth switches Q3 and Q4 are power-frequency switches. The power-frequency switches can be replaced by diodes. Specifically, during the positive half-cycle of the power-frequency AC power supply of the totem pole PFC converter, the first switch Q1 functions as a high-frequency rectifier, the second switch Q2 functions as a high-frequency main circuit, the third switch Q3 functions as a power-frequency switch and remains off, while the fourth switch Q4 functions as a power-frequency switch and remains on. During the negative half-cycle of the power-frequency AC power supply of the totem pole PFC converter, the first switch Q1 functions as a high-frequency main circuit, the second switch Q2 functions as a high-frequency rectifier, the third switch Q3 functions as a power-frequency switch and remains on, while the fourth switch Q4 functions as a power-frequency switch and remains off.

[0004] Totem-pole bridgeless PFC circuits require GaN devices to achieve their efficiency advantages when operating in continuous conduction mode (CCM), but current GaN device costs are high. Si MOS transistors can be used in both critical conduction mode (CRM) and transition conduction mode (TCM), but they cannot achieve zero voltage switching (ZVS) at high voltages in CRM, making them unsuitable for high frequency and small size. The most significant feature of TCM mode is the presence of negative inductor current, which enables zero voltage switching (ZVS). However, there are also shortcomings. The reasons are: conventional PFC control methods include current-type control and voltage-type control. Current-type control requires sampling the inductor peak current, while the peak current sampling of the totem bridgeless PFC converter is complex, difficult, and costly. Voltage-type control usually determines the on-time of its switch tube based on the error signal of the output voltage. Its on-time remains fixed within the power frequency cycle, so it is usually also called fixed on-time control (COT control). When COT control is applied in TCM mode, due to the existence of negative current, the input current is severely distorted near the zero-crossing point of the power frequency AC input, the total current harmonics (THD) are large, and the power factor value (PF value) is low. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a control method and device for a totem pole PFC converter based on the TCM mode, and a totem pole PFC converter, which can not only solve the crossover distortion problem near the zero-crossing point of the industrial frequency AC input, but also achieve zero voltage turn-on in each working cycle within the full industrial frequency cycle range.

[0006] As a first aspect of the present invention, an embodiment of a control method for a totem pole PFC converter is provided as follows:

[0007] A control method for a totem pole PFC converter, wherein each working cycle of the totem pole PFC converter comprises the following steps:

[0008] Obtain a first voltage signal V representing the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter in ;

[0009] Obtain a second voltage signal V representing the effective value of the AC voltage input to the totem pole PFC converter rms ;

[0010] Obtain a third voltage signal V representing the output DC bus voltage of the totem pole PFC converter out ;

[0011] Obtaining a first current signal I representing the magnitude of the negative value of the inductor current of the boost inductor in the totem pole PFC converter z ;

[0012] According to the third voltage signal V out and the preset voltage reference value V ref Get the totem pole PFC converter voltage loop output voltage V comp ;

[0013] According to the first voltage signal V in , the second voltage signal V rms , the voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f Open the high frequency main first conduction time T on The first on-time T on After the first interval has passed, the high-frequency rectifier tube automatically turns on;

[0014] According to the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref , then according to the inductor negative current threshold I zref and the first current signal I z The high-frequency rectifier tube is turned off based on the comparison result to achieve zero-current shutdown of the high-frequency rectifier tube, and then the high-frequency rectifier tube is kept turned off for a second interval. During the second interval, the boost inductor resonates with the drain-source junction capacitance of the high-frequency main tube and the drain-source junction capacitance of the high-frequency rectifier tube. After the second interval ends, the next working cycle begins, wherein the second interval is configured to achieve zero-voltage turn-on of the high-frequency main tube in the next working cycle.

[0015] Furthermore, according to the first voltage signal V in , the second voltage signal V rms , the voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f Open the high frequency main first conduction time T on ,include:

[0016]

[0017]

[0018] P o =V comp ×k comp

[0019] in:

[0020] L is the inductance value of the boost inductor;

[0021] P o Outputting load power for the totem pole PFC converter;

[0022] V in is the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter;

[0023] V o is the output voltage of the totem pole PFC converter;

[0024] Z r The resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates;

[0025] w r The resonant angular frequency of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates;

[0026] C oss is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance;

[0027] k comp is the set calculation coefficient.

[0028] Furthermore, according to the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref ,include:

[0029]

[0030] Among them, k a 、k b and k c is the set adjustment coefficient.

[0031] Furthermore, the second interval time is configured to achieve zero voltage switching of the high frequency main tube in the next working cycle, including: the absolute value of the minimum current in the boost inductor is i L_min The absolute value of the current in the boost inductor at the moment the high-frequency main tube is turned on in the next working cycle is i L_sw ,

[0032]

[0033]

[0034]

[0035] in:

[0036] V in is the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter;

[0037] V o is the output voltage of the totem pole PFC converter;

[0038] Z r The resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates;

[0039] L is the inductance value of the boost inductor;

[0040] C oss It is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance.

[0041] As a second aspect of the present invention, an embodiment of a control device for a totem pole PFC converter is provided as follows:

[0042] A control device for a totem pole PFC converter, comprising the following units:

[0043] The first acquisition unit is used to acquire in real time a first voltage signal V representing the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter. in ;

[0044] The second acquisition unit is used to obtain in real time the second voltage signal V that represents the effective value of the power frequency input AC voltage of the totem pole PFC converter. rms ;

[0045] The third acquisition unit is used to obtain in real time a third voltage signal V representing the output DC bus voltage of the totem pole PFC converter. out ;

[0046] The fourth acquisition unit is used to obtain in real time a first current signal I representing the magnitude of the negative value of the inductor current of the boost inductor in the totem pole PFC converter. z ;

[0047] The first execution unit is used to execute the third voltage signal V in real time. out and the preset voltage reference value V ref Get the totem pole PFC converter voltage loop output voltage V comp ;

[0048] The second execution unit is used to perform the operation according to the first voltage signal V in each working cycle. in , the second voltage signal Vrms , the voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f The first conduction time T of the high frequency main tube is turned on on The first on-time T on After the first interval has passed, the high-frequency rectifier tube automatically turns on;

[0049] The third execution unit is used to perform the operation according to the first voltage signal V in each working cycle. in and the first current preset value I f Determine the inductor negative current threshold I zref , then according to the inductor negative current threshold I zref and the first current signal I z The high-frequency rectifier tube is turned off based on the comparison result to achieve zero-current shutdown of the high-frequency rectifier tube, and then the high-frequency rectifier tube is kept turned off for a second interval. During the second interval, the boost inductor resonates with the drain-source junction capacitance of the high-frequency main tube and the drain-source junction capacitance of the high-frequency rectifier tube. After the second interval ends, the next working cycle begins, wherein the second interval is configured to achieve zero-voltage turn-on of the high-frequency main tube in the next working cycle.

[0050] Furthermore, the second execution unit generates a voltage signal V in , the second voltage signal V rms , the voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f Open the high frequency main first conduction time T on ,include:

[0051]

[0052]

[0053] P o =V comp ×k comp

[0054] in:

[0055] L is the inductance value of the boost inductor;

[0056] P o Outputting load power for the totem pole PFC converter;

[0057] V inis the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter;

[0058] V o is the output voltage of the totem pole PFC converter;

[0059] Z r The resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates;

[0060] w r The resonant angular frequency of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates;

[0061] C oss is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance;

[0062] k comp is the set calculation coefficient.

[0063] Furthermore, the third execution unit generates a voltage signal V in each working cycle according to the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref ,include:

[0064]

[0065] Among them, k a 、k b and k c is the set adjustment coefficient.

[0066] Furthermore, the third execution unit configures the second interval time in each working cycle to achieve zero voltage switching of the high frequency main tube in the next working cycle, including: the absolute value of the minimum current in the boost inductor is i L_min The absolute value of the current in the boost inductor at the moment the high-frequency main tube is turned on in the next working cycle is i L_sw :

[0067]

[0068]

[0069]

[0070] in:

[0071] V in is the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter;

[0072] V o is the output voltage of the totem pole PFC converter;

[0073] Z r The resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates;

[0074] L is the inductance value of the boost inductor;

[0075] C oss It is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance.

[0076] As a third aspect of the present invention, an embodiment of a totem pole PFC converter is provided as follows:

[0077] A totem pole PFC converter comprises an embodiment of any one of the control devices described above.

[0078] Compared with the existing fixed on-time control method, the embodiment of the present invention has the following advantages:

[0079] 1. The embodiment of the present invention collects the electrical parameters of the totem pole PFC converter and calculates the conduction time of the high-frequency main in real time, thereby solving the problem of crossover distortion near the zero-crossing point of the power frequency AC input, optimizing the overall control effect of the totem pole PFC converter, and reducing the total harmonic distortion relatively.

[0080] 2. The embodiment of the present invention samples the negative value of the inductor current of the boost inductor to control the turn-off time of the high-frequency rectifier tube accordingly, thereby achieving ZVS turn-on of the high-frequency tube in the next working cycle. This enables the totem pole PFC converter to achieve zero voltage turn-on of the high-frequency tube and zero current turn-off of the high-frequency rectifier tube in each working cycle within the full power frequency cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 A circuit diagram of a known totem pole PFC converter;

[0082] Figure 2 This is a step diagram of an embodiment of a control method for a totem pole PFC converter according to the first embodiment of the present invention;

[0083] Figure 3 This is a schematic diagram of an embodiment of a control device for a totem pole PFC converter according to a second embodiment of the present invention;

[0084] Figure 4 This is a functional block diagram of a totem pole PFC converter according to a third embodiment of the present invention;

[0085] Figure 5 1 is a main waveform diagram of a totem pole PFC converter according to a third embodiment of the present invention;

[0086] Figure 6 The third embodiment of the present invention is the totem pole PFC converter Z r i L -V ds Plots in the phase plane;

[0087] Figure 7 This is a diagram showing the effect of the conduction time of the totem pole PFC converter main circuit in a power frequency cycle according to the third embodiment of the present invention;

[0088] Figure 8 This is a schematic diagram of theoretical calculation of inductor current control effect of a totem pole PFC converter according to the third embodiment of the present invention;

[0089] Figure 9 This is a diagram showing the boost inductor current control effect of the totem pole PFC converter according to the third embodiment of the present invention. DETAILED DESCRIPTION

[0090] Typical embodiments embodying the features and advantages of the present disclosure will be described in detail in the following description with reference to the accompanying drawings. It should be understood that the present disclosure is capable of various variations in different embodiments without departing from the scope of the present disclosure, and the description and drawings are essentially illustrative of these variations and are not intended to limit the present disclosure.

[0091] In addition, the figures of this disclosure are merely schematic diagrams of the present disclosure and are not necessarily drawn to scale. Identical reference numbers in the figures denote identical or similar parts, and therefore repeated descriptions thereof will be omitted. Some of the blocks shown in the figures are functional entities that do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented using software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0092] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0093] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0094] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0095] It should be understood that, in the specification, claims and drawings, when a step is described as being connected to another step, the step may be directly connected to the other step, or be connected to the other step through a third step; when an element / unit is described as being "connected" to another element / unit, the element / unit may be "directly connected" to the other element / unit, or be "connected" to the other element / unit through a third element / unit.

[0096] First embodiment

[0097] This embodiment provides a control method for a totem pole PFC converter. Figure 2 This is a step diagram of an embodiment of the control method of the totem pole PFC converter of the first embodiment of the present invention. Figure 2 , each working cycle of the totem pole PFC converter includes the following steps:

[0098] S101, obtaining a first voltage signal Vin representing the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter; obtaining a second voltage signal Vrms representing the effective value of the power frequency input AC voltage of the totem pole PFC converter; obtaining a third voltage signal Vout representing the output DC bus voltage of the totem pole PFC converter; obtaining a first current signal Iz representing the negative value of the inductor current of the boost inductor in the totem pole PFC converter;

[0099] The first voltage signal V is obtained in the above steps in , the second voltage signal V rms , the third voltage signal V out and the first current signal I z All of this is done in real time;

[0100] The first voltage signal V that represents the instantaneous value of the AC voltage input to the totem pole PFC converter is obtained. inThis can be achieved by sampling; obtaining a second voltage signal V representing the effective value of the AC voltage input to the totem pole PFC converter rms This can be achieved by sampling or calculating by the controller's internal algorithm; obtaining a third voltage signal V representing the output DC bus voltage of the totem pole PFC converter out This can be achieved by sampling; obtaining a first current signal I representing the negative value of the inductor current of the boost inductor in the totem pole PFC converter z It can be achieved through sampling. In specific implementation, those skilled in the art can select a method for obtaining each parameter according to needs, and this embodiment does not limit the method for obtaining these parameters.

[0101] S102, according to the third voltage signal V out and the preset voltage reference value V ref Get the totem pole PFC converter voltage loop output voltage V comp ;

[0102] The function of the voltage loop is to achieve the stability of the output voltage of the totem pole PFC converter. The output voltage of the voltage loop can be obtained by sampling the output voltage of the totem pole PFC converter and comparing it with the preset voltage reference value. comp The specific design of this embodiment is not specified, and those skilled in the art can make choices based on actual conditions.

[0103] S103, according to the first voltage signal V in , the second voltage signal V rms , voltage loop output voltage V c omp, the first voltage preset value V o and the first current preset value I f Open the high frequency main first conduction time T on ; First on-time T on After the first interval has passed, the high-frequency rectifier tube automatically turns on;

[0104] The first voltage preset value V o The design is determined according to the circuit parameters, for example, it can be designed to be 400V. The specific design is not specified in this embodiment, and those skilled in the art can choose according to actual conditions;

[0105] Among them, the first current preset value I f The design is determined according to the actual negative current demand, for example, it can be designed to be 1A. The specific design is not specified in this embodiment, and those skilled in the art can choose according to the actual situation;

[0106] It should be noted that the totem pole PFC converter of the present invention is input with 50Hz AC power, and the operating frequency of the totem pole PFC converter of the present invention is high frequency. Those skilled in the art will know that in each half cycle of the power frequency, the totem pole PFC converter will complete multiple working cycles. In addition, each time the totem pole PFC converter of the present invention enters the next half cycle of the power frequency, the roles of the high frequency main tube and the high frequency rectifier tube will be swapped. Therefore, the first conduction time T of the high frequency main tube in step S103 is on The switching tubes targeted may vary in different working cycles.

[0107] S104, according to the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref , then according to the inductor negative current threshold I zref and the first current signal I z The high-frequency rectifier tube is turned off based on the comparison result to achieve zero-current shutdown of the high-frequency rectifier tube, and then the high-frequency rectifier tube is kept turned off for a second interval. During the second interval, the boost inductor resonates with the drain-source junction capacitance of the high-frequency main tube and the drain-source junction capacitance of the high-frequency rectifier tube. After the second interval ends, the next working cycle begins, and the second interval is configured to achieve zero-voltage turn-on of the high-frequency main tube in the next working cycle.

[0108] Furthermore, according to the first voltage signal V in , the second voltage signal V rms , voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f Open the high frequency main first conduction time T on ,include:

[0109]

[0110]

[0111] P o =V comp ×k comp

[0112] in:

[0113] L is the inductance of the boost inductor;

[0114] P o The power of the totem pole PFC converter output load;

[0115] V inis the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter;

[0116] V o is the output voltage of the totem pole PFC converter;

[0117] Z r The resonant impedance is the resonance of the boost inductor with the high-frequency main drain-source junction capacitance and the high-frequency rectifier tube drain-source junction capacitance. The junction capacitance includes two, namely the high-frequency main drain-source junction capacitance and the high-frequency rectifier tube drain-source junction capacitance. Since the source junction capacitance of the two high-frequency switching tubes both participate in the resonance, even though the high-frequency main and high-frequency rectifier tubes may be interchanged in different power frequency half-cycles, it will not affect the calculation.

[0118] w r The resonant angular frequency of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance;

[0119] C oss It is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance;

[0120] k comp is the set calculation coefficient.

[0121] Among them, k comp The design of needs to be designed in combination with hardware circuit parameters, for example, it can be designed to be 0.0031. The specific design method is not specified in this embodiment, and those skilled in the art can choose according to actual conditions.

[0122] Furthermore, according to the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref ,include:

[0123]

[0124] Among them, k a 、k b and k c is the set adjustment coefficient.

[0125] where k a 、k b and k c The design needs to be adjusted according to actual needs and input current performance. To facilitate debugging, k a Generally, it is fixed to 1, k b Affects the peak and valley values ​​of the input current waveform, k c Affects the steepness of the input current waveform, for example, it can be designed to be k a =1,k b=0.1, k c =10. The specific design of this embodiment is not specified, and those skilled in the art can make a choice based on actual conditions.

[0126] Furthermore, the second interval is configured to achieve zero voltage switching of the high frequency main tube in the next working cycle, including: the absolute value of the minimum current in the boost inductor is i L_min The absolute value of the current in the boost inductor when the high-frequency tube is turned on in the next working cycle is i L_sw ,

[0127]

[0128]

[0129]

[0130] in:

[0131] V in is the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter;

[0132] V o is the output voltage of the totem pole PFC converter;

[0133] Z r It is the resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance and the high-frequency rectifier tube drain-source junction capacitance;

[0134] L is the inductance of the boost inductor;

[0135] C oss It is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance.

[0136] This embodiment collects the electrical parameters of the totem pole PFC converter and calculates the on-time of the high-frequency main tube and the off-time of the high-frequency synchronous tube in real time, thereby solving the problem of crossover distortion near the zero-crossing point of the power frequency AC input, optimizing the overall control effect of the totem pole PFC converter, and reducing the total harmonic distortion.

[0137] In addition, this embodiment samples and calculates the main electrical parameters in the power stage circuit to obtain the on-time of the high-frequency main tube and the off-time of the high-frequency synchronous rectifier tube. This can achieve zero-voltage turn-on of the high-frequency main tube in each working cycle and zero-current turn-off of the high-frequency synchronous tube in each working cycle within the full power frequency cycle range.

[0138] Second embodiment

[0139] This embodiment provides a control device for a totem pole PFC converter. Figure 3This is a schematic diagram of an embodiment of a control device for a totem pole PFC converter according to the second embodiment of the present invention. Figure 3 , including the following units:

[0140] The first acquisition unit is used to obtain in real time the first voltage signal V that represents the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter. in ;

[0141] The second acquisition unit is used to obtain in real time the second voltage signal V that represents the effective value of the AC voltage input to the totem pole PFC converter. rms ;

[0142] The third acquisition unit is used to obtain in real time the third voltage signal V representing the output DC bus voltage of the totem pole PFC converter out ;

[0143] The fourth acquisition unit is used to obtain in real time a first current signal I representing the negative value of the inductor current of the boost inductor in the totem pole PFC converter. z ;

[0144] The first execution unit is used to perform the operation according to the third voltage signal V in each working cycle. out and the preset voltage reference value V ref Get the totem pole PFC converter voltage loop output voltage V comp ;

[0145] The second execution unit is used to generate a voltage signal V in , the second voltage signal V rms , voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f Open the high frequency main first conduction time T on ; First on-time T on After the first interval has passed, the high-frequency rectifier tube automatically turns on;

[0146] The third execution unit is used to perform the operation according to the first voltage signal V in each working cycle. in and the first current preset value I f Determine the inductor negative current threshold I zref , then according to the inductor negative current threshold I zref and the first current signal I zThe high-frequency rectifier tube is turned off based on the comparison result to achieve zero-current shutdown of the high-frequency rectifier tube, and then the high-frequency rectifier tube is kept turned off for a second interval. During the second interval, the boost inductor resonates with the drain-source junction capacitance of the high-frequency main tube and the drain-source junction capacitance of the high-frequency rectifier tube. After the second interval ends, the next working cycle begins, and the second interval is configured to achieve zero-voltage turn-on of the high-frequency main tube in the next working cycle.

[0147] Furthermore, the second execution unit generates a voltage signal V in each working cycle. in , the second voltage signal V rms , voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f The first conduction time Ton of the high-frequency main circuit is activated, including:

[0148]

[0149]

[0150] P o =V comp ×k comp

[0151] in:

[0152] L is the inductance of the boost inductor;

[0153] P o The power of the totem pole PFC converter output load;

[0154] V in is the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter;

[0155] V o is the output voltage of the totem pole PFC converter;

[0156] Z r It is the resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance and the high-frequency rectifier tube drain-source junction capacitance;

[0157] w r The resonant angular frequency of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance;

[0158] C oss is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance;

[0159] k comp is the set calculation coefficient.

[0160] Among them, k comp The design of needs to be combined with hardware circuit parameters, for example, it can be designed to be 0.0031. The specific design method is not specified in this embodiment, and those skilled in the art can choose according to actual conditions.

[0161] Furthermore, the third execution unit performs the following operations in each working cycle according to the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref ,include:

[0162]

[0163] Among them, k a 、k b and k c is the set adjustment coefficient.

[0164] where k a 、k b and k c The design needs to be adjusted according to actual needs and input current performance. To facilitate debugging, k a Generally, it is fixed to 1, k b Affects the peak and valley values ​​of the input current waveform, k c Affects the steepness of the input current waveform, for example, it can be designed to be k a =1,k b =0.1, k c =10. The specific design of this embodiment is not specified, and those skilled in the art can make a choice based on actual conditions.

[0165] Furthermore, the three execution units configure the second interval time in each working cycle to achieve zero voltage switching of the high frequency main tube in the next working cycle, including: the absolute value of the minimum current in the boost inductor is i L_min The absolute value of the current in the boost inductor when the high-frequency tube is turned on in the next working cycle is i L_sw ,

[0166]

[0167]

[0168]

[0169] in:

[0170] V in is the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter;

[0171] Vo is the output voltage of the totem pole PFC converter;

[0172] Z r It is the resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance and the high-frequency rectifier tube drain-source junction capacitance;

[0173] L is the inductance of the boost inductor;

[0174] C oss It is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance.

[0175] The functions of the various units in the control device of this embodiment are consistent with the related actions performed in the corresponding steps of the control method of the first embodiment, and the implementation points and beneficial effects are consistent, so they will not be described repeatedly.

[0176] Third embodiment

[0177] This embodiment provides a totem pole PFC converter, including any specific implementation of the control device in the second embodiment. Figure 4 FIG. 1 is a functional block diagram of a totem pole PFC converter according to an embodiment of the present invention, wherein:

[0178] The third acquisition module and the first execution module are multiplexed by the comparator E / A, and the execution logic is: the output voltage of the totem pole PFC converter is converted into V after being sampled by the resistor divider. out / k is input to the non-inverting terminal of the operational amplifier E / A, and the reference voltage V ref The input is to the inverting terminal of the comparator E / A, and the output terminal of the comparator outputs the voltage loop output voltage V comp .

[0179] The functions of the second execution module and the third execution module are implemented by the hardware circuit in the dotted box, where T on The calculator inputs the first voltage signal V in , the second voltage signal V rms , voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f Calculate the first conduction time T of the high frequency tube on , the PWM driver turns on the high frequency tube for the first conduction time T on ; First on-time T on After the first interval has passed, the high-frequency rectifier tube automatically turns on; zref The calculator inputs the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref, and then the comparator CMP is used to determine the negative current threshold value I zref and the first current signal I z A comparison is performed, and a comparison result is output to a PWM driver. The PWM generator turns off the high-frequency rectifier tube according to the comparison result to achieve zero-current shutdown of the high-frequency rectifier tube, and then keeps the high-frequency rectifier tube turned off for a second interval time. During the second interval time, the boost inductor resonates with the drain-source junction capacitance of the high-frequency main tube and the drain-source junction capacitance of the high-frequency rectifier tube. After the second interval time ends, the next working cycle begins, wherein the second interval time is configured to achieve zero-voltage turn-on of the high-frequency main tube in the next working cycle.

[0180] Figure 5 This is the main waveform diagram of the totem pole PFC converter of the third embodiment of the present invention. Due to the symmetry of the totem pole PFC converter circuit topology, the operating modes of the positive and negative half cycles of the AC voltage are symmetrical. In order to facilitate the analysis and derivation of the expression, the following will be combined with Figure 4 and Figure 5 Analyze the working state of the totem pole PFC converter circuit in the positive half cycle of AC voltage. The main voltage and current waveforms of each working mode are shown in Figure 4 Among them, SW is the high-frequency main tube driving logic, SR is the high-frequency synchronous tube driving logic, i L is the inductor current, V ds is the high frequency main drain-source voltage.

[0181]

t0,t2

[0182]

[0183]

t2, t3

[0184]

[0185]

[0186] In the following [t6, t8] time period, the boost inductor resonates with the high-frequency main drain-source junction capacitance and the high-frequency rectifier tube drain-source junction capacitance. According to the above formula, Z r represents the resonant impedance of the resonant network, w r Represents the resonant angular frequency of the resonant network.

[0187]

t3, t6

[0188]

[0189]

t6, t8

[0190]

[0191]

[0192] In the working state of the entire working cycle, the boost inductor current is at its negative maximum value at time t7, and the absolute value of the boost inductor current resonant minimum value i L_min The calculation formula is as follows:

[0193]

[0194] In the working state of the entire working cycle, the inductor current is negative at the time when the high-frequency main tube is turned on in the next working cycle (i.e., time t8). The absolute value of the current value in the boost inductor at time t8 is i L_sw The calculation formula is as follows:

[0195]

[0196]

[0197] From formula (5), we can get:

[0198] Z r i L (t) = Z r i L (t6)cos(w r (t-t6))+(V in -V o )sin(w r (t-t6)) (9)

[0199] From formula (6), we can get:

[0200] V in -V ds =-Z r i L (t6)sin(w r(t-t6))+(V in -V o )cos(w r (t-t6)) (10)

[0201] From formula (9) and formula (10), we can get:

[0202] [Z r i L (t)] 2 +[V ds -V in ] 2 =Z r i L 2 (t6)+(V in -V o ) 2 (11)

[0203] According to formula (11), we can get r i L -V ds Curves in the phase plane, such as Figure 6 The root locus of the reverse resonance of the boost inductor current is a circular arc with the center at (0, V in ), the radius is

[0204] Combine Figure 4 It can be seen that:

[0205]

[0206]

[0207] From formulas (12), (13), and (14), we can see that:

[0208]

[0209] At t7, the boost inductor current i L The lowest point is:

[0210]

[0211] At t8, the high-frequency tube is turned on, and the boost inductor current i L for:

[0212]

[0213] Considering the negative resonance of the boost inductor current, the conduction time T on It consists of two parts:

[0214] Ton =T [t6,t8] +T [t8,t2] (18)

[0215] For formula (18), the calculation formulas of each part are as follows:

[0216]

[0217]

[0218] Among them, t θ3 From the phasor diagram we can get:

[0219]

[0220] From equations (19), (20), and (21), we can get the conduction time T of the high-frequency main tube: on :

[0221]

[0222] It should be noted that, when the control accuracy requirement is not high, the negative resonance process (t6, t8) of the boost inductor current can be ignored, which can greatly simplify the control calculation complexity. on The calculation formula is as follows:

[0223]

[0224] This embodiment obtains the following by theoretical calculation of the expression: Figure 7 Theoretical curve of high-frequency main conduction time T under the positive half cycle of medium AC voltage on1 and T on2 , T on1 To ignore the control result of the negative resonance process of the boost inductor current, T on2 This is the control result of negative resonance of the boost inductor current. Figure 8 The following is the measured boost inductor current waveform. The relevant calculation parameters are as follows:

[0225] The input AC voltage is 210Vac / 50Hz, the output load is 1000W, and the first voltage preset value is V o The voltage is 400V, the inductance of the boost inductor is 75uH, and the parallel equivalent junction capacitance is 1nF.

[0226] The totem-pole PFC converter provided in this embodiment samples electrical parameters within the totem-pole PFC converter to calculate the on-time of the high-frequency main tube. It also samples the negative value of the boost inductor's inductor current to control the turn-off timing of the high-frequency rectifier tube, achieving zero-voltage (ZVS) conduction of the high-frequency main tube in the next operating cycle. This advantage fundamentally solves the problem of crossover distortion near the zero-crossing point of the power-frequency AC input and achieves ZVS for the entire power-frequency cycle. Furthermore, digital control is employed, simplifying implementation and also applicable to situations where diodes are used in place of switching tubes in the low-frequency bridge arm.

[0227] The terms used in the above embodiments are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in various forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope of the appended claims. Therefore, all changes and modifications that fall within the scope of the claims or their equivalents are intended to be covered by the appended claims.

Claims

1. A control method for a totem pole PFC converter, characterized in that: Each working cycle of the totem pole PFC converter includes the following steps: Obtain a first voltage signal V representing the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter in ; Obtain a second voltage signal V representing the effective value of the AC voltage input to the totem pole PFC converter rms ; Obtain a third voltage signal V representing the output DC bus voltage of the totem pole PFC converter out ; Obtaining a first current signal I representing the magnitude of the negative value of the inductor current of the boost inductor in the totem pole PFC converter z ; According to the third voltage signal V out and the preset voltage reference value V ref Get the totem pole PFC converter voltage loop output voltage V comp ; According to the first voltage signal V in , the second voltage signal V rms , the voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f Open the high frequency main first conduction time T on The first on-time T on After the first interval has passed, the high-frequency rectifier tube automatically turns on; According to the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref , then according to the inductor negative current threshold I zref and the first current signal I z The high-frequency rectifier tube is turned off based on the comparison result to achieve zero-current shutdown of the high-frequency rectifier tube, and then the high-frequency rectifier tube is kept turned off for a second interval. During the second interval, the boost inductor resonates with the drain-source junction capacitance of the high-frequency main tube and the drain-source junction capacitance of the high-frequency rectifier tube. After the second interval ends, the next working cycle begins, wherein the second interval is configured to achieve zero-voltage turn-on of the high-frequency main tube in the next working cycle; According to the first voltage signal V in , the second voltage signal V rms , the voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f Open the high frequency main first conduction time T on , include: P o =V comp ×k comp in: L is the inductance value of the boost inductor; P o Outputting load power for the totem pole PFC converter; V in is the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter; V o is the output voltage of the totem pole PFC converter; Z r The resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates; w r The resonant angular frequency of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates; C oss is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance; k comp is the set calculation coefficient; According to the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref ,include: Among them, k a 、k b and k c is the set adjustment coefficient.

2. The control method according to claim 1, characterized in that: The second interval time is configured to achieve zero voltage switching of the high frequency main tube in the next working cycle, including: the absolute value of the minimum current in the boost inductor is i L_min The absolute value of the current in the boost inductor at the moment the high-frequency main tube is turned on in the next working cycle is i L_sw , in: V in is the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter; V o is the output voltage of the totem pole PFC converter; Z r The resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates; L is the inductance value of the boost inductor; C oss It is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance.

3. A control device for a totem pole PFC converter, characterized in that: Includes the following units: The first acquisition unit is used to acquire in real time a first voltage signal V representing the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter. in ; The second acquisition unit is used to obtain in real time the second voltage signal V that represents the effective value of the power frequency input AC voltage of the totem pole PFC converter. rms ; The third acquisition unit is used to obtain in real time a third voltage signal V representing the output DC bus voltage of the totem pole PFC converter. out ; The fourth acquisition unit is used to obtain in real time a first current signal I representing the magnitude of the negative value of the inductor current of the boost inductor in the totem pole PFC converter. z ; The first execution unit is used to execute the third voltage signal V in real time. out and the preset voltage reference value V ref Get the totem pole PFC converter voltage loop output voltage V comp ; The second execution unit is used to perform the operation according to the first voltage signal V in each working cycle. in , the second voltage signal V rms , the voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f The first conduction time T of the high frequency main tube is turned on on The first on-time T on After the first interval has passed, the high-frequency rectifier tube automatically turns on; The third execution unit is used to perform the operation according to the first voltage signal V in each working cycle. in and the first current preset value I f Determine the inductor negative current threshold I zref , then according to the inductor negative current threshold I zref and the first current signal I z The high-frequency rectifier tube is turned off based on the comparison result to achieve zero-current shutdown of the high-frequency rectifier tube, and then the high-frequency rectifier tube is kept turned off for a second interval. During the second interval, the boost inductor resonates with the drain-source junction capacitance of the high-frequency main tube and the drain-source junction capacitance of the high-frequency rectifier tube. After the second interval ends, the next working cycle begins, wherein the second interval is configured to achieve zero-voltage turn-on of the high-frequency main tube in the next working cycle; The second execution unit performs the operation according to the first voltage signal V in each working cycle. in , the second voltage signal V rms , the voltage loop output voltage V comp , the first voltage preset value V o and the first current preset value I f Open the high frequency main first conduction time T on , include: P o =V comp ×k comp in: L is the inductance value of the boost inductor; P o Outputting load power for the totem pole PFC converter; V in is the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter; V o is the output voltage of the totem pole PFC converter; Z r The resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates; w r The resonant angular frequency of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates; C oss is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance; k comp is the set calculation coefficient; The third execution unit is configured to execute the first voltage signal V in and the first current preset value I f Determine the inductor negative current threshold I zref ,include: Among them, k a 、k b and k c is the set adjustment coefficient.

4. The control device according to claim 3, characterized in that The third execution unit configures the second interval time in each working cycle to achieve zero voltage switching of the high frequency main tube in the next working cycle, including: the absolute value of the minimum current in the boost inductor is i L_min The absolute value of the current in the boost inductor at the moment the high-frequency main tube is turned on in the next working cycle is i L_sw : in: V in is the instantaneous value of the power frequency input AC voltage of the totem pole PFC converter; V o is the output voltage of the totem pole PFC converter; Z r The resonant impedance of the boost inductor, the high-frequency main drain-source junction capacitance, and the high-frequency rectifier tube drain-source junction capacitance resonates; L is the inductance value of the boost inductor; C oss It is the sum of the capacitance of the high-frequency main drain-source junction capacitance and the capacitance of the high-frequency rectifier tube drain-source junction capacitance.

5. A totem pole PFC converter, characterized in that: The control device comprises the control device according to any one of claims 3 to 4.

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