Totem pole PFC circuit control method, control system and electrical equipment

Abstract

The invention discloses a totem-pole PFC circuit control method and system and electrical equipment, the totem-pole PFC circuit comprises an inductor, a first switch and a second switch, the first switch and the second switch are on a fast bridge arm, and the control method comprises the following steps: determining a basic value of a modulation wave according to an input voltage and an output voltage; when the current of the inductor meets the specified low current condition, the compensation value of the modulation wave is determined according to the current value of the inductor, the dead zone duration and the maximum value of the carrier wave, the dead zone duration is a specified numerical value, and the compensation value is in negative correlation with the current current of the inductor; determining an actual value of the modulated wave according to the basic value and the compensation value of the modulated wave; and the first switch and the second switch are controlled according to the actual value of the modulation wave. According to the invention, the compensation value of the modulation wave is determined according to the dead zone duration, so that the modulation wave is adjusted, and the output voltage can be basically equal to the expected value.

Description

Technical Field

[0001] The present disclosure relates to the field of power electronics technology, and in particular to a control method, a control system and an electrical device of a totem pole PFC circuit. Background Art

[0002] Totem pole PFC (Power Factor Correction) circuit has been widely used in power adapters due to its advantages such as low conduction loss and simple control.

[0003] In the totem pole PFC circuit, the upper and lower switches of the fast bridge arm are switched on and off alternately. In the process of the two switches switching on and off alternately, in order to prevent the two switches from being turned on at the same time, a short "dead zone" is often inserted between the driving signals of the two switches, that is, during the "dead zone", the two switches are turned off.

[0004] However, during the dead time, due to the presence of the freewheeling diode in parallel with the switch tube, the inductor current will continue to make the specific freewheeling diode conduct, that is, during the dead time, the freewheeling diode can be approximately equivalent to one of the switch tubes still remaining in the turned-on state, which will cause the output voltage to differ greatly from the expected value. Summary of the invention

[0005] The embodiments of the present disclosure provide a control method, control system and electrical equipment for a totem pole PFC circuit, which can solve the above technical problems existing in the related art. The technical solution is as follows:

[0006] In a first aspect, a control method of a totem pole PFC circuit is provided, wherein the totem pole PFC circuit comprises an inductor, a first switch and a second switch, wherein the first switch and the second switch are on a fast bridge arm, and the control method comprises:

[0007] Determine the basic value of the modulation wave according to the input voltage and the output voltage;

[0008] When the current current of the inductor meets the specified low current condition, the compensation value of the modulated wave is determined according to the current current value of the inductor, the dead zone duration and the maximum value of the carrier, wherein the dead zone duration is a specified value and the compensation value is negatively correlated with the current current of the inductor;

[0009] Determining the actual value of the modulation wave according to the basic value and the compensation value of the modulation wave;

[0010] The first switch and the second switch are controlled according to an actual value of the modulated wave.

[0011] In a possible implementation, the specified low current condition is:

[0012] The absolute value of the current of the inductor is smaller than a specified value.

[0013] In a possible implementation manner, the specified value is determined according to a parasitic capacitance value of the first switch and a parasitic capacitance value of the second switch.

[0014] In a possible implementation, the specified value is expressed by the formula σ=(C1+C2)V dc / T0 is determined, where σ is the specified value, C1 is the parasitic capacitance value of the first switch, C2 is the parasitic capacitance value of the second switch, V dc is the voltage of the DC bus, and T0 is the specified duration.

[0015] In a possible implementation, determining the compensation value of the modulation wave according to the current current of the inductor, the dead zone duration, and the maximum value of the carrier wave includes:

[0016] The compensation value of the modulation wave is obtained by the formula Determine, where ΔC is the compensation value of the modulation wave, C prd is the maximum value of the carrier, T d is the dead zone duration, T sw is the switching period, σ is the specified value, i L is the current of the inductor, and satisfies -σ≤i L ≤σ.

[0017] In a possible implementation, the control method further includes:

[0018] When the current of the inductor does not meet the specified low current condition, the compensation value of the modulation wave is determined according to the dead zone duration, the current direction of the inductor and the maximum value of the carrier.

[0019] In a possible implementation, determining the compensation value of the modulation wave according to the dead zone duration, the current direction of the inductor, and the maximum value of the carrier wave includes:

[0020] When the current direction of the inductor is positive, the compensation value is given by the formula Determine, where ΔC is the compensation value of the modulation wave, C prd is the maximum value of the carrier, T d is the dead zone duration, T sw is the switching cycle;

[0021] When the current direction of the inductor is negative, the compensation value is calculated by the formula Sure.

[0022] In a possible implementation manner, determining the actual value of the modulated wave according to the basic value and the compensation value of the modulated wave includes:

[0023] The sum of the basic value of the modulated wave and the compensation value of the modulated wave is determined as the actual value of the modulated wave.

[0024] In a second aspect, a totem pole PFC circuit control system is provided, wherein the totem pole PFC circuit control system is used to implement the control method provided in the first aspect and possible implementations thereof.

[0025] According to a third aspect, an electrical device is provided, wherein the electrical device comprises the totem pole PFC circuit control system provided by the second aspect and possible implementations thereof.

[0026] The beneficial effects of the technical solution provided by the present disclosure include at least:

[0027] During the operation of the totem pole PFC circuit, during the dead time, although the first switch and the second switch are both closed, the inductor current continues to turn on the specific freewheeling diode. This short time can be approximately equivalent to that one of the first switch and the second switch (the auxiliary switch) remains turned on. The present disclosure determines the compensation value of the modulation wave according to the dead time to adjust the modulation wave, that is, it can extend the turn-on time of the auxiliary switch of the first switch and the second switch and shorten the turn-on time of the other switch of the first switch and the second switch, thereby reducing the deviation of the output voltage caused by the dead time from the expected value.

[0028] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 is a circuit diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0031] Figure 2 is a circuit diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0032] Figure 3 is a compensation value variation diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0033] Figure 4 is a compensation value variation diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0034] Figure 5 is a control signal diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0035] Figure 6 is a control signal diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0036] Figure 7 is a control signal diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0037] Figure 8 is a control signal diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0038] Fig. 9 is a control signal diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0039] Fig.10 is a control signal diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0040] Fig.11 is a control effect diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0041] Fig.12 is a control effect diagram of a totem pole PFC circuit provided by an embodiment of the present disclosure;

[0042] Fig.13 It is a control signal diagram of a totem pole PFC circuit in the related art;

[0043] Fig.14 It is a control signal diagram of a totem pole PFC circuit in the related art;

[0044] Fig.15 It is a control effect diagram of a totem pole PFC circuit in the related art.

[0045] Reference numerals:

[0046] 11. first switch; 12. second switch; 13. first diode; 14. second diode; 15. first capacitor; 16. second capacitor;

[0047] 21. a third switch; 22. a fourth switch; 23. a third diode; 24. a fourth diode;

[0048] 3. Inductor; 3a. First end; 3b. Second end;

[0049] 4. Support capacitor. DETAILED DESCRIPTION

[0050] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0051] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0052] like Figure 1 As shown, the totem pole PFC circuit includes a fast bridge arm, a slow bridge arm, an inductor 3 and a supporting capacitor 4. The fast bridge arm includes a first switch 11, a first diode 13, a first capacitor 15, a second switch 12, a second diode 14 and a second capacitor 16. The slow bridge arm includes a third switch 21, a third diode 23, a fourth switch 22 and a fourth diode 24. Among them, the first diode 13 is connected in parallel with the first switch 11, which can be a separate component or a body diode of the first switch 11, and the first capacitor 15 is a parasitic capacitor of the first switch 11; the second diode 14 is connected in parallel with the second switch 12, which can be a separate component or a body diode of the second switch 12, and the second capacitor 16 is a parasitic capacitor of the second switch 12; the third diode 23 is connected in parallel with the third switch 21, which can be a separate component or a body diode of the third switch 21; the fourth diode 24 is connected in parallel with the fourth switch 22, which can be a separate component or a body diode of the fourth switch 22. The inductor 3 is electrically connected to the middle node of the slow bridge arm and is connected to the AC source. The supporting capacitor 4 is respectively connected in parallel with the first bridge arm and the second bridge arm, and is mainly used to stabilize the voltage of the totem pole PFC.

[0053] Regulation Figure 1 The current direction of the inductor 3 is positive.

[0054] like Figure 1As shown, when the totem pole PFC circuit operates in the inverter working mode and the current of the inductor 3 is positive, the third switch 21 in the slow bridge arm is normally open and the fourth switch 22 is normally closed. When the first switch 11 is closed and the second switch 12 is opened, a loop is formed between the positive pole of the DC bus, the third switch 21, the AC source, the inductor 3, the second switch 12 and the negative pole of the DC bus; when the first switch 11 is opened and the second switch 12 is closed, a loop is formed between the first end 3a of the inductor 3, the first switch 11, the third switch 21, the AC source and the second end 3b of the inductor 3. In the dead time, the first switch 11 and the second switch 12 are both closed. Due to the freewheeling effect of the first diode 13, a loop is formed between the first end 3a of the inductor 3, the first diode 13, the third switch 21, the AC source and the second end 3b of the inductor 3. At this time, due to the existence of the first diode 13, it is equivalent to that the first switch 11 is still kept in the open state, the current of the inductor 3 continues to decrease, and the voltage across the second switch 12 is kept at a high level.

[0055] like Figure 2 As shown, when the totem pole PFC circuit operates in the inverter working mode and the current of the inductor 3 is negative, the third switch 21 in the slow bridge arm is normally closed and the fourth switch 22 is normally open. When the first switch 11 is turned on and the second switch 12 is turned off, a loop is formed between the positive electrode of the DC bus, the first switch 11, the inductor 3, the AC source, the fourth switch 22 and the negative electrode of the DC bus; when the first switch 11 is turned off and the second switch 12 is turned on, a loop is formed between the second end 3b of the inductor 3, the AC source, the fourth switch 22, the second switch 12 and the first end 3a of the inductor 3. In the dead time, the first switch 11 and the second switch 12 are both turned off. Due to the freewheeling effect of the second diode 14, a loop is formed between the second end 3b of the inductor 3, the AC source, the fourth switch 22, the second diode 14 and the first end 3a of the inductor 3. At this time, due to the existence of the second diode 14, it is equivalent to that the second switch 12 is still kept in the open state, the current of the inductor 3 continues to decrease, and the voltage across the second switch 12 is kept at a low level.

[0056] Fig.13 and Fig.14 The control signals and related parameter change diagrams when the current direction of the inductor 3 is positive and negative in the related art are shown respectively, wherein G11 is the control signal of the first switch 11, when G11 is at a high level, the first switch 11 is turned on, when G11 is at a low level, the first switch 11 is turned off; G12 is the control signal of the second switch 12, when G12 is at a high level, the second switch 12 is turned on, when G12 is at a low level, the second switch 12 is turned off. Lis the current of the inductor 3, and vds is the voltage across the second switch 12. The control signals of the first switch 11 and the second switch 12 are mainly obtained by comparing the modulation wave and the carrier wave, in which the carrier wave is taken as an example of a sawtooth wave.

[0057] Combination Figure 1 and Fig.13 As shown, when the current direction of the inductor 3 is positive, during the dead time, G11 is at a low level, G12 is at a low level, the first switch 11 and the second switch 12 are both closed, and due to the freewheeling effect of the first diode 13, the current of the inductor 3 continues to decrease, and the voltage vds across the second switch 12 is maintained at a high level. Further, if you want to make the duration of vds at a high level 50%, the relevant technology often sets the modulation wave to 0.5 (i.e. 50% of the maximum value of the carrier), and the demodulated signal generated by comparing the modulation wave and the carrier is as follows: Fig.13 However, after the dead zone is inserted, assuming that the dead zone accounts for 2% of the switching time, the first switch 11 and the second switch 12 are both turned on for 48% of the time, and the time when VDS is at a high level is also 48%, which is different from the ideal output voltage.

[0058] Combination Figure 2 and Fig.14 As shown, when the current of the inductor 3 is negative, during the dead time, G11 is at a low level, G12 is at a low level, the first switch 11 and the second switch 12 are both closed, and due to the freewheeling effect of the second diode 14, the current of the inductor 3 continues to decrease (negative value, so the slope is positive), and the voltage vds across the second switch 12 is maintained at a low level. Further, if you want to make the duration of vds at a high level be 50%, the relevant technology often sets the modulation wave to 0.5, and the demodulation signal generated by comparing the modulation wave and the carrier is as follows Fig.14 As shown, however, after the dead zone is inserted, assuming that the dead zone accounts for 2% of the switching time, the first switch 11 and the second switch 12 are both turned on for 48% of the time, and the time when VDS is at a high level is 52%, which is different from the ideal output voltage.

[0059] In summary, it can be seen that during the dead time, the freewheeling diode is approximately equivalent to one of the switch tubes remaining turned on, which will cause the output voltage of the fast bridge arm to differ greatly from the expected value. Fig.15 As shown, it can be found that the output voltage will be significantly distorted.

[0060] In order to solve the above technical problems, the present disclosure provides a control method for a totem pole PFC circuit, such as Figure 1 As shown, the totem pole PFC circuit includes an inductor 3, a first switch 11 and a second switch 12, the first switch 11 and the second switch 12 are on a fast bridge arm, and the control method includes:

[0061] S1. Determine the basic value of the modulation wave according to the input voltage and the output voltage;

[0062] S21, when the current current of the inductor 3 meets the specified low current condition, determine the compensation value of the modulation wave according to the current current of the inductor 3, the dead zone duration and the maximum value of the carrier, wherein the dead zone duration is a specified value and the compensation value is negatively correlated with the current current of the inductor 3;

[0063] S3, determining the actual value of the modulation wave according to the basic value and the compensation value of the modulation wave;

[0064] S4. Control the first switch 11 and the second switch 12 according to the actual value of the modulation wave.

[0065] During the operation of the totem pole PFC circuit, during the dead time, although the first switch 11 and the second switch 12 are both closed, the inductor current continues to turn on the specific freewheeling diode. This short time can be approximately equivalent to that one of the first switch 11 and the second switch 12 (the auxiliary switch) remains turned on. The present disclosure determines the compensation value of the modulation wave according to the dead time to adjust the modulation wave, that is, it can extend the turn-on time of the auxiliary switch in the first switch 11 and the second switch 12 and shorten the turn-on time of the other switch in the first switch 11 and the second switch 12, thereby reducing the deviation of the output voltage from the expected value caused by the dead time, so that the output voltage is basically equal to the expected value.

[0066] Wherein, step S1 is performed at the beginning of the control cycle.

[0067] Among them, when the current of the inductor 3 is positive, compared with the related art, the value of the modulation wave can be reduced, thereby reducing the turn-on time of the first switch 11 and increasing the turn-on time of the second switch 12, so that the time for the intermediate node of the first switch 11 and the second switch 12 to maintain a high level rises to the desired time, so that the output voltage of the fast bridge arm is basically equal to the expected value.

[0068] Among them, when the current of the inductor 3 is negative, compared with the related art, the value of the modulation wave can be increased, so that the turn-on time of the first switch 11 can be increased and the turn-on time of the second switch 12 can be reduced, so that the time for the intermediate node of the first switch 11 and the second switch 12 to maintain a high level is reduced to the desired time, so that the output voltage of the fast bridge arm is basically equal to the expected value.

[0069] Among them, the first switch 11, the second switch 12, the third switch 21 and the fourth switch 22 can be, for example but not limited to, IGBT (Insulated Gate Bipolar Transistor), MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), GaN (Gallium Nitride) switch tube or SiC (Silicon Carbide) switch tube.

[0070] The first switch 11 and the first diode 13 may be an integral structure, for example, the first switch 11 is a MOSFET, and the first diode 13 is a body diode of the first switch 11. Similarly, the second switch 12 and the second diode 14 may be an integral structure, the third switch 21 and the third diode 23 may be an integral structure, and the fourth switch 22 and the fourth diode 24 may be an integral structure.

[0071] In some embodiments, determining the actual value of the modulated wave according to the basic value and the compensation value of the modulated wave includes: determining the sum of the basic value of the modulated wave and the compensation value of the modulated wave as the actual value of the modulated wave.

[0072] Among them, when the current of the inductor 3 is positive, the compensation value of the modulation wave is negative, so that the actual value of the modulation wave can be made smaller than its basic value, thereby reducing the turn-on time of the first switch 11 and increasing the turn-on time of the second switch 12, so that the time for the middle node of the first switch 11 and the second switch 12 to maintain a high level rises to the desired time, so that the output voltage of the fast bridge arm is basically equal to the expected value.

[0073] Among them, when the current of the inductor 3 is negative, the compensation value of the modulation wave is positive, so that the actual value of the modulation wave can be greater than its basic value, thereby increasing the turn-on time of the first switch 11 and reducing the turn-on time of the second switch 12, so that the time for the intermediate node of the first switch 11 and the second switch 12 to maintain a high level is reduced to the expected time, so that the output voltage of the fast bridge arm is basically equal to the expected value.

[0074] In some embodiments, the specified low current condition is that the absolute value of the current of the inductor 3 is less than a specified value.

[0075] The specified value is an artificially set value, and the value is set mainly to reduce the distortion of the output voltage waveform of the fast bridge arm when the current of the inductor 3 is around the zero point.

[0076] The specified low current value may be a preset value or a value that can be changed through wireless transmission or the like.

[0077] In some embodiments, the specified value is determined according to the parasitic capacitance value of the first switch 11 and the parasitic capacitance value of the second switch 12 .

[0078] Among them, when the current of the inductor 3 is small, when the states of the first switch 11 and the second switch 12 are switched, the first capacitor 15 (the parasitic capacitor of the first switch 11) and the second capacitor 16 (the parasitic capacitor of the second switch 12) cannot quickly realize the charging and discharging process, which causes a delay in the state switching of the first switch 11 and the second switch 12, which causes the voltage of the intermediate node of the first switch 11 and the second switch 12 to change relatively slowly, resulting in a large difference between the output voltage of the fast bridge arm and the expected value.

[0079] In the disclosed embodiment, the specified value is determined according to the parasitic capacitance value of the first switch 11 and the parasitic capacitance value of the second switch 12, which can further reduce the distortion of the waveform of the output voltage of the fast bridge arm when the absolute value of the current in the inductor 3 is less than the specified value.

[0080] In some embodiments, the specified value is given by the formula σ=(C1+C2)V dc / T0 is determined, where σ is a specified value, C1 is the parasitic capacitance value of the first switch 11, C2 is the parasitic capacitance value of the second switch 12, V dc is the voltage of the DC bus, and T0 is the specified duration.

[0081] The specified time length T0 is a manually set value. When the commutation time is less than the specified time length T0, it can be considered that the time required to complete the charging and discharging of the first capacitor 15 and the second capacitor 16 can be ignored. At this time, the corresponding current of the inductor 3 is the specified value σ.

[0082] The value of the specified time length T0 can be set to a value much smaller than the dead time. For example, if the dead time length is 1μs, the value of T0 is set to a value one order of magnitude smaller than the dead time, that is, 100ns. dc =400V, and T0 is 100ns, the calculated value of the specified value σ is 4A.

[0083] In some embodiments, according to the current current of the inductor 3, the dead time and the maximum value of the carrier, it includes:

[0084] The compensation value of the modulation wave is given by the formula Determine, where ΔC is the compensation value of the modulation wave, C prd is the maximum value of the carrier, T d is the dead zone duration, T sw is the switching period, σ is a specified value, i L is the current of inductor 3, and satisfies -σ≤i L ≤σ.

[0085] Among them, the smaller the current, the longer the time it takes for the first capacitor 15 and the second capacitor 16 to realize the charging and discharging process when switching the states of the first switch 11 and the second switch 12, and the more obvious the state switching delay of the first switch 11 and the second switch 12, which will cause the voltage of the intermediate node of the first switch 11 and the second switch 12 to change slower, thereby causing the voltage of the intermediate node to change slower, resulting in a greater difference between the output voltage of the fast bridge arm and the expected value.

[0086] In the embodiment of the present disclosure, when the current of the inductor 3 is small, the compensation value is determined according to the current of the inductor 3, thereby ensuring the optimization effect on the output voltage waveform.

[0087] In some embodiments, the control method further comprises:

[0088] S22. When the current of the inductor 3 does not meet the specified low current condition, determine the compensation value of the modulation wave according to the dead zone duration, the current direction of the inductor 3 and the maximum value of the carrier.

[0089] Among them, when the current of the inductor 3 is large, when the states of the first switch 11 and the second switch 12 are switched, the first capacitor 15 and the second capacitor 16 can quickly realize the charging and discharging process, and the state switching time of the first switch 11 and the second switch 12 can be ignored. In this case, the compensation value of the modulation wave is determined according to the dead zone duration, the current direction of the inductor 3 and the maximum value of the carrier, and there is no need to determine the compensation value according to the current size of the inductor 3, so that the distortion of the output voltage waveform can be reduced.

[0090] In some embodiments, the compensation value of the modulation wave is determined according to the dead zone duration, the current direction of the inductor 3 and the maximum value of the carrier wave, including:

[0091] When the current direction of inductor 3 is positive, the compensation value is given by the formula Determine, among which, C prd is the maximum value of the carrier, T d is the dead zone duration, T sw is the switching cycle;

[0092] When the current direction of inductor 3 is negative, the compensation value is given by the formula Sure.

[0093] Among them, when the current of the inductor 3 is positive, the compensation value is negative, so that the turn-on time of the first switch 11 can be reduced and the turn-on time of the second switch 12 can be increased, so that the time for the middle node of the first switch 11 and the second switch 12 to maintain a high level rises to the desired time, so that the output voltage of the fast bridge arm is basically equal to the expected value.

[0094] Among them, when the current of the inductor 3 is negative, the compensation value is positive, so that the turn-on time of the first switch 11 can be increased and the turn-on time of the second switch 12 can be reduced, so that the time for the intermediate node of the first switch 11 and the second switch 12 to maintain a high level is reduced to the desired time, so that the output voltage of the fast bridge arm is basically equal to the expected value.

[0095] In the disclosed embodiment, the totem pole PFC circuit can work in both the inverter mode and the rectifier mode. Figure 3 As shown, the current of inductor 3 is in phase with the voltage of the AC source, and the compensation value is related to the current of inductor 3. In the inverter working mode, Figure 4 As shown, the current of the inductor 3 is 90° out of phase with the voltage of the AC source, and the compensation value is also related to the current of the inductor 3. That is, whether the totem pole PFC circuit works in the inverter mode or the rectifier mode, the compensation value is only related to the current of the inductor 3.

[0096] The control method of the totem pole PFC circuit disclosed in the embodiment of the present disclosure will be described below with reference to two examples.

[0097] In this example, the time proportion of the voltage of the middle node of the desired fast bridge arm to maintain a high level is the switching period T sw 50% of the dead time T d The time proportion of the switching cycle T sw 2%, the carrier wave is taken as an example. In order to achieve this goal, in step S1, the base value of the modulated wave is set to half of the maximum value of the carrier wave, that is, the maximum value of the carrier wave C prd is set to 1, and the basic value of the modulation wave is set to 0.5. The control method will be described below in combination with various states of the current of the inductor 3.

[0098] (I) The current direction of inductor 3 is positive

[0099] like Figure 5As shown, when the current current of the inductor 3 does not meet the specified low current condition, the compensation value of the modulation wave is -0.02, and the compensation value is added to the basic value of the modulation wave to obtain the actual value of the modulation wave of 0.48. At this time, in the demodulated signal obtained by comparing the actual value of the modulation wave with the carrier, the high level occupies 52% of the duration of the switching cycle. Through the demodulated signal and the dead zone duration, it is obtained that the duty cycle of the first switch 11 is 46%, and the duty cycle of the second switch 12 is 50%. In the process of closing the first switch 11, due to the freewheeling effect of the first diode 13, the voltage of the middle node is maintained at a high level, and when the state of the first switch 11 is switched from off to on, the first capacitor 15 and the second capacitor 16 can quickly realize the charging and discharging process, and the state switching time of the first switch 11 can be ignored. At this time, the voltage of the middle node is quickly switched to a low level, so that the voltage of the middle node of the fast bridge arm can be kept at a high level for a time that is substantially equal to the switching period T sw 50% of.

[0100] like Figure 6 As shown, when the current current of the inductor 3 meets the specified low current condition, if the compensation value of the modulation wave is taken as -0.02, the compensation value is added to the basic value of the modulation wave, and the actual value of the modulation wave is 0.48. At this time, as above, the duty cycle of the first switch 11 is 46%, and the duty cycle of the second switch 12 is 50%. In the process of closing the first switch 11, due to the freewheeling effect of the first diode 13, the voltage of the middle node is maintained at a high level, and when the state of the first switch 11 is switched from off to on, since the current current of the inductor 3 does not meet the specified low current condition, the first capacitor 15 and the second capacitor 16 cannot quickly realize the charging and discharging process, and the state switching time of the first switch 11 cannot be ignored. At this time, the middle node needs to be quickly switched to a low level after a certain period of time (unacceptable time), so that the voltage of the middle node of the fast bridge arm can be kept at a high level for a time that is significantly greater than the switching period T sw 50%, resulting in a large deviation between the final output voltage and the expected value.

[0101] Therefore, when the current of the inductor 3 meets the specified low current condition, this example makes the compensation value negatively correlated with the current of the inductor 3. Figure 7 As shown, the actual current value i in the inductor 3 LWhen the ratio to the specified value σ is 0.5, the compensation value of the modulation wave is taken as -0.01, and the compensation value is added to the basic value of the modulation wave to obtain the actual value of the modulation wave of 0.49. At this time, as above, the duty cycle of the first switch 11 is 47%, and the duty cycle of the second switch 12 is 49%. In the process of closing the first switch 11, due to the freewheeling effect of the first diode 13, the voltage of the intermediate node is maintained at a high level, and when the state of the first switch 11 is switched from off to on, since the current current of the inductor 3 does not meet the specified low current condition, the first capacitor 15 and the second capacitor 16 cannot quickly realize the charging and discharging process, and the state switching time of the first switch 11 is approximately 47% of the switching period T. sw 1%, at this time, the intermediate node needs to go through a certain period of time (approximately the switching cycle T sw 1% of the switching period T) is quickly switched to a low level, so that the voltage of the middle node of the fast bridge arm can be kept at a high level for a time approximately equal to the switching period T sw 50% of.

[0102] (ii) The current direction of inductor 3 is negative

[0103] like Figure 8 As shown, when the current current of the inductor 3 does not meet the specified low current condition, the compensation value of the modulation wave is 0.02, and the compensation value is added to the basic value of the modulation wave to obtain the actual value of the modulation wave of 0.52. At this time, in the demodulated signal obtained by comparing the actual value of the modulation wave with the carrier, the high level occupies 48% of the duration of the switching cycle. Through the demodulated signal and the dead zone duration, it is obtained that the duty cycle of the first switch 11 is 50%, and the duty cycle of the second switch 12 is 46%. In the process of closing the second switch 12, due to the freewheeling effect of the second diode 14, the voltage of the middle node is maintained at a low level, and when the state of the second switch 12 is switched from closed to open, the first capacitor 15 and the second capacitor 16 can quickly realize the charging and discharging process, and the state switching time of the second switch 12 can be ignored. At this time, the voltage of the middle node is quickly switched to a high level, so that the voltage of the middle node of the fast bridge arm can be kept at a high level for a time that is substantially equal to the switching period T sw 50% of.

[0104] like Fig. 9As shown, when the current current of the inductor 3 meets the specified low current condition, if the compensation value of the modulation wave is taken as 0.02, the compensation value is added to the basic value of the modulation wave, and the actual value of the modulation wave is 0.52. At this time, as above, the duty cycle of the first switch 11 is 50%, and the duty cycle of the second switch 12 is 46%. In the process of closing the second switch 12, due to the freewheeling effect of the second diode 14, the voltage of the middle node is maintained at a low level, and when the state of the second switch 12 is switched from off to on, since the current current of the inductor 3 does not meet the specified low current condition, the first capacitor 15 and the second capacitor 16 cannot quickly realize the charging and discharging process, and the state switching time of the second switch 12 cannot be ignored. At this time, the middle node needs to be quickly switched to a high level after a certain period of time (unacceptable time), so that the voltage of the middle node of the fast bridge arm can be kept at a high level for a time that is significantly less than the switching period T sw 50%, resulting in a large deviation between the final output voltage and the expected value.

[0105] Therefore, when the current of the inductor 3 meets the specified low current condition, this example makes the compensation value negatively correlated with the current of the inductor 3. Fig.10 As shown, the actual current value i in the inductor 3 L When the ratio to the specified value σ is 0.5, the compensation value of the modulation wave is taken as 0.01, and the compensation value is added to the basic value of the modulation wave to obtain the actual value of the modulation wave as 0.51. At this time, as above, the duty cycle of the first switch 11 is 49%, and the duty cycle of the second switch 12 is 47%. In the process of closing the first switch 11, due to the freewheeling effect of the first diode 13, the voltage of the intermediate node is maintained at a high level, and when the state of the second switch 12 is switched from off to on, since the current current of the inductor 3 does not meet the specified low current condition, the first capacitor 15 and the second capacitor 16 cannot quickly realize the charging and discharging process, and the state switching time of the second switch 12 is approximately 49% of the switching period T. sw 1%, at this time, the intermediate node needs to go through a certain period of time (approximately the switching cycle T sw 1% of the switching period T) is quickly switched to a high level, so that the voltage of the middle node of the fast bridge arm can be kept at a high level for a time approximately equal to the switching period T sw 50% of.

[0106] in, Fig.11 The figure shows the waveform of the final output voltage in the inverter mode, without considering whether the current of the inductor 3 meets the specified low current condition, and only determining the compensation value according to the current direction of the inductor 3. It can be seen that the output voltage will be significantly distorted before and after the zero point of the output voltage. Fig.12As shown, after considering whether the current current of the inductor 3 meets the specified low current condition and determining the compensation value according to the current size of the inductor 3, the distortion before and after the zero point of the output voltage can be significantly reduced.

[0107] Based on the same concept, an embodiment of the present disclosure further provides a totem pole PFC circuit control system, and the totem pole PFC circuit control system is used to implement the control method provided above.

[0108] The totem pole PFC circuit control system includes a data acquisition unit, a data processing unit and a switch control unit. The data processing unit is used to determine the basic value of the modulation wave according to the input voltage and the output voltage, and the data acquisition unit is used to collect the current value of the inductor 3. Afterwards, the data processing unit will determine whether the current value of the inductor 3 meets the specified low current condition.

[0109] When the current current value of the inductor 3 meets the specified low current condition, the data processing unit will determine the compensation value of the modulation wave according to the current current value of the inductor 3, the dead zone length and the basic maximum value of the modulation wave carrier; when the current current value of the inductor 3 does not meet the specified low current condition, the data processing unit will determine the compensation value of the modulation wave according to the current current direction of the inductor 3, the dead zone length and the basic maximum value of the modulation wave carrier.

[0110] Afterwards, the data processing unit determines the actual value of the modulation wave according to the basic value and the compensation value of the modulation wave, and thereafter, the data processing generates the duty ratio of the first switch 11 and the second switch 12 according to the actual value of the modulation wave and the dead zone duration. The switch control unit controls the first switch 11 and the second switch 12 according to the duty ratio of the first switch 11 and the second switch 12.

[0111] Based on the same concept, an embodiment of the present disclosure further provides an electrical device, which includes the totem pole PFC circuit control system provided above.

[0112] The electrical device may be, for example but not limited to, a UPS (Uninterruptible Power Supply), a charging pile, or a charging module of various energy storage devices.

[0113] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0114] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present disclosure. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0115] In the description of the present disclosure, it is necessary to understand that the orientation or positional relationship indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present disclosure; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0116] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0117] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present disclosure.

[0118] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A control method for a totem pole PFC circuit, characterized in that: The totem pole PFC circuit includes an inductor, a first switch and a second switch, wherein the first switch and the second switch are on a fast bridge arm, and the control method includes: Determine the basic value of the modulation wave according to the input voltage and the output voltage; When the current current of the inductor meets the specified low current condition, the compensation value of the modulated wave is determined according to the current current value of the inductor, the dead zone duration and the maximum value of the carrier, wherein the dead zone duration is a specified value and the compensation value is negatively correlated with the current current of the inductor; Determining the actual value of the modulation wave according to the basic value and the compensation value of the modulation wave; The first switch and the second switch are controlled according to an actual value of the modulated wave.

2. The control method according to claim 1, characterized in that: The specified low current conditions are: The absolute value of the current of the inductor is smaller than a specified value.

3. The control method according to claim 2, characterized in that: The specified value is determined according to a parasitic capacitance value of the first switch and a parasitic capacitance value of the second switch.

4. The control method according to claim 3, characterized in that: The specified value is calculated by the formula σ=(C1+C2)V dc / T0 is determined, where σ is the specified value, C1 is the parasitic capacitance value of the first switch, C2 is the parasitic capacitance value of the second switch, V dc is the voltage of the DC bus, and T0 is the specified duration.

5. The control method according to claim 2, characterized in that: The method of determining the compensation value of the modulation wave according to the current current of the inductor, the dead zone duration and the maximum value of the carrier wave comprises: The compensation value of the modulation wave is obtained by the formula Determine, where ΔC is the compensation value of the modulation wave, C prd is the maximum value of the carrier, T d is the dead zone duration, T sw is the switching period, σ is the specified value, i L is the current of the inductor, and satisfies -σ≤i L ≤σ.

6. The control method according to claim 1, characterized in that: The control method further comprises: When the current of the inductor does not meet the specified low current condition, the compensation value of the modulation wave is determined according to the dead zone duration, the current direction of the inductor and the maximum value of the carrier.

7. The control method according to claim 6, characterized in that: The determining of the compensation value of the modulation wave according to the dead zone duration, the current direction of the inductor and the maximum value of the carrier wave comprises: When the current direction of the inductor is positive, the compensation value is given by the formula Determine, where ΔC is the compensation value of the modulation wave, C prd is the maximum value of the carrier, T d is the dead zone duration, T sw is the switching cycle; When the current direction of the inductor is negative, the compensation value is calculated by the formula Sure.

8. The control method according to any one of claims 1 to 7, characterized in that: Determining the actual value of the modulated wave according to the basic value and the compensation value of the modulated wave includes: The sum of the basic value of the modulated wave and the compensation value of the modulated wave is determined as the actual value of the modulated wave.

9. A totem pole PFC circuit control system, characterized in that: The totem pole PFC circuit control system is used to implement the control method described in any one of claims 1-8.

10. An electrical device, characterized in that: The electrical device includes the totem pole PFC circuit control system described in claim 9.

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