Control method of bidirectional power supply H-bridge topology circuit

Abstract

The invention provides a control method of a bidirectional power supply H-bridge topology circuit, and belongs to the technical field of power electronics. The method comprises the steps that whether a to-be-controlled switching period is a target switching period or not is determined, and the target switching period is a second switching period before the switching period where the alternating current zero crossing point moment in the bidirectional power supply H-bridge topology circuit is located; under the condition that the to-be-controlled switching period is the target switching period, a pulse width modulation (PWM) comparison value corresponding to the target switching period is set to be a target value, and the target value is a value lower limit of a PWM count value; and controlling a PWM fast tube of the bidirectional power supply H-bridge topology circuit based on the PWM comparison value corresponding to the target switching period. According to the invention, harmonic current can be prevented from being generated in the bidirectional power supply H-bridge topology circuit, and the service life of electrical equipment is prolonged.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of power electronics, and particularly relates to a control method for a bidirectional power H-bridge topology circuit. Background Art

[0002] With the emergence of smart grids and the rise of renewable energy, the application of bidirectional power supplies has become increasingly widespread. A bidirectional power supply is a device that can convert alternating current to direct current and vice versa.

[0003] The bidirectional power supply controls four switching tubes in the bidirectional power H-bridge topology circuit through PWM (Pulse Width Modulation), thereby realizing power rectification and power inversion.

[0004] Currently, in the bidirectional power H-bridge topology circuit, harmonic currents are generated at the zero-crossing moment of alternating current, reducing the service life of the bidirectional power supply. Summary of the Invention

[0005] The present disclosure provides a control method for a bidirectional power H-bridge topology circuit, a control system for a bidirectional power H-bridge topology circuit, and an electrical device, which can solve the technical problems existing in the related art. The technical solutions are as follows:

[0006] In a first aspect, the present disclosure provides a control method for a bidirectional power H-bridge topology circuit, the method comprising:

[0007] Determining whether a to-be-controlled switching period is a target switching period, wherein the target switching period is the second switching period before the switching period in which the zero-crossing moment of alternating current in the bidirectional power H-bridge topology circuit is located;

[0008] When the to-be-controlled switching period is the target switching period, setting a Pulse Width Modulation (PWM) comparison value corresponding to the target switching period to a target value, wherein the target value is the lower limit of the value range of the PWM count value;

[0009] Controlling a PWM fast tube of the bidirectional power H-bridge topology circuit based on the PWM comparison value corresponding to the target switching period.

[0010] In a possible implementation, the determining whether a to-be-controlled switching period is a target switching period includes:

[0011] Obtaining a real-time voltage value of alternating current in the bidirectional power H-bridge topology circuit;

[0012] Determining a first phase angle of alternating current based on the real-time voltage value;

[0013] Determine whether the switching period to be controlled is the target switching period based on the first phase angle of the alternating current.

[0014] In a possible implementation, the determining whether the switching period to be controlled is the target switching period based on the first phase angle of the alternating current includes:

[0015] Determine whether the switching period to be controlled is the target switching period when the first phase angle and the second phase angle meet the specified conditions, where the second phase angle is the phase angle of the alternating current determined based on the real-time voltage value of the alternating current in the bidirectional power supply H-bridge topology circuit obtained in the previous switching period, and the specified conditions are: Or θ 1 is the first phase angle, θ 2 is the second phase angle, and T is a specified value.

[0016] In a possible implementation, the specified value T is in the interval (150Xπ, 250Xπ], where X is the duration of the switching period of the PWM fast switch.

[0017] In a possible implementation, the specified value T is in the interval (250Xπ, 350Xπ], where X is the duration of the switching period of the PWM fast switch.

[0018] In a possible implementation, the switching period to be controlled is the switching period at the current moment.

[0019] In a possible implementation, the switching period to be controlled is the first switching period after the switching period at the current moment.

[0020] In a possible implementation, the lower limit of the value of the PWM count is 0.

[0021] In a second aspect, the present disclosure provides a bidirectional power supply H-bridge topology circuit control system, and the bidirectional power supply H-bridge topology circuit control system is used to implement the control method in the first aspect and its possible implementations.

[0022] In a third aspect, the present disclosure provides an electrical appliance, and the electrical appliance device includes the bidirectional power supply H-bridge topology circuit control system described in the second aspect.

[0023] The technical solution provided by the present disclosure at least includes the following beneficial effects:

[0024] The present disclosure provides a control method for a bidirectional power H-bridge topology circuit. The controller can determine the second switching period before the switching period where the zero-crossing moment of the alternating current is located as the target switching period, and set the PWM comparison value of the target switching period to 0, so that within the switching period where the zero-crossing moment of the alternating current is located, the PWM waveforms input to the first switching tube and the third switching tube are consistent, thereby avoiding sudden switching between different operating states of the bidirectional power H-bridge topology circuit, and further avoiding the generation of harmonic currents in the bidirectional power H-bridge topology circuit, and improving the service life of electrical equipment.

[0025] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. In the drawings:

[0027] Figure 1 is a circuit schematic diagram of a bidirectional power H-bridge topology circuit provided by an embodiment of the present disclosure;

[0028] Figure 2 is a level schematic diagram of an input to a PWM fast tube and a PWM fast tube provided by the related art;

[0029] Figure 3 is a level schematic diagram of an input to a PWM fast tube and a PWM fast tube provided by an embodiment of the present disclosure;

[0030] Figure 4 is an equivalent circuit diagram of a bidirectional power H-bridge topology circuit in a first state provided by an embodiment of the present disclosure;

[0031] Figure 5 is an equivalent circuit diagram of a bidirectional power H-bridge topology circuit in a second state provided by an embodiment of the present disclosure;

[0032] Figure 6 is a schematic flow chart of a control method for a bidirectional power H-bridge topology circuit provided by an embodiment of the present disclosure;

[0033] Figure 7 is a schematic flow chart of a control method for a bidirectional power H-bridge topology circuit provided by an embodiment of the present disclosure;

[0034] Figure 8 is a schematic diagram of the relationship between the real-time voltage value and the phase angle of the alternating current in a bidirectional power H-bridge topology circuit provided by an embodiment of the present disclosure;

[0035] Figure 9It is a schematic structural diagram of a SOGI phase-locked loop provided by an embodiment of the present disclosure.

[0036] Legend Explanation

[0037] 1. First switching transistor;

[0038] 2. Second switching transistor;

[0039] 3. Third switching transistor;

[0040] 4. Fourth switching transistor;

[0041] 5. Inductor;

[0042] 51. First end of the inductor; 52. Second end of the inductor;

[0043] 6. AC source;

[0044] 7. DC source.

[0045] Through the above-mentioned drawings, specific embodiments of the present disclosure have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present disclosure in any way, but to illustrate the concept of the present disclosure to those skilled in the art by referring to specific embodiments. Detailed Embodiment

[0046] To make the objectives, technical solutions, and advantages of the present disclosure clearer, the following will further describe the embodiments of the present disclosure in detail with reference to the drawings.

[0047] It should be noted that, without conflict, the embodiments in the present disclosure and the features in the embodiments may be combined with each other. The following will describe the present disclosure in detail with reference to the drawings and in combination with the embodiments.

[0048] Figure 1 It is a schematic structural diagram of a bidirectional power H-bridge topology circuit shown in an embodiment of the present disclosure. As Figure 1 shown, the bidirectional power H-bridge topology circuit includes a first switching transistor 1, a second switching transistor 2, a third switching transistor 3, a fourth switching transistor 4, an inductor 5, an AC source 6, a DC source 7, and a controller (not shown in the figure). The first switching transistor 1 and the second switching transistor 2 are connected in series to form a first bridge arm, the third switching transistor 3 and the fourth switching transistor 4 are connected in series to form a second bridge arm, the first bridge arm, the first bridge arm, and the DC source 7 are connected in parallel. The first end 51 of the inductor is connected to the midpoint of the first bridge arm (unless otherwise specified in the present disclosure, the connection means electrical connection), the second end 52 of the inductor is connected to one end of the AC source 6, and the other end of the AC source 6 is connected to the midpoint of the second bridge arm. Refer to Figure 1, in the left-to-right direction in the figure, the AC source 6 is the input source of the circuit, and the DC source 7 is the output source of the circuit. The bidirectional power H-bridge topology circuit can achieve the rectification function. Correspondingly, in the right-to-left direction in the figure, the DC source 7 is the input source of the circuit, and the AC source 6 is the output source of the circuit. The bidirectional power H-bridge topology circuit can achieve the inversion function. In implementation, the controller is respectively connected to the four switching tubes in the bidirectional power H-bridge topology circuit, and controls the four switching tubes in PWM mode. Specifically, the controller controls the four switching tubes to conduct or cut off by sending high-level or low-level signals to the switching tubes, so as to control the bidirectional power H-bridge topology circuit to switch between different working states. In the bidirectional power H-bridge topology circuit, the third switching tube 3 and the fourth switching tube 4 are called slow tubes, because the change frequency of the level values controlling the third switching tube 3 and the fourth switching tube 4 is relatively low and equal to the frequency of the alternating current, 50 Hz. The third switching tube 3 can be called the upper bridge of the PWM slow tube, and the fourth switching tube 4 can be called the lower bridge of the PWM slow tube. The first switching tube 1 and the second switching tube 2 are called fast tubes, because the change frequency of the level values controlling the first switching tube 1 and the second switching tube 2 is very high, usually three orders of magnitude higher than that of the slow tubes. For example, it is 50 kHz. The first switching tube 1 can be called the upper bridge of the PWM fast tube, and the second switching tube 2 can be called the lower bridge of the PWM fast tube.

[0049] Exemplarily, the first switching tube 1, the second switching tube 2, the third switching tube 3, and the fourth switching tube 4 can all be MOS tubes (Metal-Oxide-Semiconductor Field-Effect Transistor).

[0050] Next, the detailed introduction of how the controller determines to input high-level or low-level signals to the PWM fast tubes is as follows:

[0051] Specifically, the controller can determine to input high-level or low-level signals to the above 4 switching tubes based on the PWM count value in the carrier wave and the calculated PWM comparison value. As Figure 2 shown, Figure 2 The upper part is the schematic diagram of the principle for the controller to determine the input level of the first switching tube 1 (i.e., the upper bridge of the PWM fast tube). The controller can generate a carrier wave, calculate the PWM comparison value according to the load condition of the bidirectional power H-bridge topology circuit, and control the PWM fast tubes of the bidirectional power H-bridge topology circuit based on the same PWM comparison value, so that the duty cycles of the upper bridge of the PWM fast tube and the lower bridge of the PWM fast tube change.

[0052] See Figure 2, the carrier wave is a triangular wave. Each carrier wave period corresponds to one switching period of the PWM fast switch. The upper limit of the PWM count value is 1000, and the lower limit is 0. Within each switching period, the PWM count value of the carrier wave uniformly rises from 0 to 1000 over time and then falls from 1000 to 0. For the first switching tube 1 (i.e., the upper bridge of the PWM fast switch): For each switching period, at the rising edge of the switching period, the controller can compare the PWM count value with the PWM comparison value. When the PWM count value is less than the PWM comparison value, the controller determines to input a high level to the first switching tube 1. When the PWM count value is higher than the PWM comparison value, the controller determines to input a low level to the first switching tube 1; at the falling edge of the switching period, the controller can compare the PWM count value with the PWM comparison value. When the PWM count value is less than the PWM comparison value, the controller determines to input a low level to the first switching tube 1. When the PWM count value is higher than the PWM comparison value, the controller determines to input a high level to the first switching tube 1. In this regard, for the first switching tube 1, it can be understood that for each switching period, during the process of the PWM count value gradually rising, when the PWM count value encounters the PWM comparison value, it determines to input a low level. During the process of the PWM count value gradually falling, when the PWM count value encounters the PWM comparison value, it determines to input a high level. When the PWM count value does not encounter the PWM comparison value, it maintains the originally input level.

[0053] Correspondingly, the logic for determining whether to input a high level or a low level for the second switching tube 2 (i.e., the lower bridge of the PWM fast switch) is opposite to that of the first switching tube 1. It can be understood that: for each switching period, during the process of the PWM count value gradually rising, when the PWM count value encounters the PWM comparison value, it determines to input a high level. During the process of the PWM count value gradually falling, when the PWM count value encounters the PWM comparison value, it determines to input a low level. Within the entire switching period, when the PWM count value does not encounter the PWM comparison value, it maintains the originally input level.

[0054] In addition, in Figure 2 , the PWM comparison value applied in the current switching period will be loaded at the start time of the next switching period (i.e., the position where the PWM count value of the next switching period is equal to 0). See Figure 2, if the PWM comparison value applied in the first switching cycle is 13, then this PWM comparison value (i.e., CMP = 13 in the figure) will be loaded at the start of the second switching cycle. That is, in the second switching cycle, at the rising edge, for the part where the PWM count value is from 0 to 12, since the PWM count value does not encounter the PWM comparison value 13, the input is determined to be the original level (high level). When the PWM count value is 13, the input is determined to be low level. Thereafter, for the part where the PWM count value ranges from 14 to 1000 and then back to 14, since the PWM count value does not encounter the PWM comparison value 13, the input is always determined to be the original level (low level). When the PWM count value is 13 again, since it is at the falling edge at this time, the input is determined to be high level until the end of this switching cycle. Meanwhile, at any moment in the second switching cycle, if the applied PWM comparison value is 12, then in the third switching cycle, the input high or low level will be determined based on the PWM comparison value of 12. The specific steps are as described above and will not be elaborated here.

[0055] In addition, the steps for the controller to determine the high or low level input to the PWM slow tube are as follows:

[0056] It should be noted that the low change frequency of the level value input to the PWM slow tube (i.e., the third switching tube 3 and the fourth switching tube 4) mentioned above does not mean that the duration of the switching cycle of the PWM slow tube is long. Instead, it means that in multiple consecutive switching cycles, either high level or low level is input continuously, resulting in a low change frequency of the level value input to the PWM slow tube. See Figure 2 , the controller determines the high or low level input to the PWM slow tube with the same carrier. Taking the third switching tube 3 as an example, as Figure 2 shown, when it is necessary to input a low level to the third switching tube 3, the controller determines the PWM comparison value of the third switching tube 3 to be 0. When it is necessary to input a high level to the third switching tube 3, the controller determines the PWM comparison value of the third switching tube 3 to be 1000. The change frequency of the level value input to the PWM slow tube is equal to the frequency of the alternating current in the bidirectional power H-bridge topology circuit. That is, the controller determines the PWM comparison value of the third switching tube 3 to be 0 in 1000 consecutive switching cycles. Subsequently, in 1000 consecutive switching cycles, the controller determines the PWM comparison value of the third switching tube 3 to be 1000. And the first PWM comparison value of 1000 is applied in the first switching cycle before the switching cycle where the zero-crossing moment is located.

[0057] Next, the reasons for the harmonic current generated by the bidirectional power H-bridge topology circuit will be introduced:

[0058] As Figure 2 shown, the six switching cycles shown in the figure are 13, 12, 11, 10, 950, 949, and 948 respectively. In Figure 2During the sixth switching period in, the alternating current passes through the zero crossing in the bidirectional power H-bridge topology circuit. Correspondingly, in Figure 2 During the sixth switching period in, the duty cycle of the first switching transistor 1 changes significantly, from 0.01 in the previous switching period to 0.95.

[0059] (1) Refer to Figure 2 , for the fifth switching period of the first switching transistor 1 shown in the figure, before the PWM count value at the falling edge drops to 10, the controller determines to input a low level to the first switching transistor 1, and the first switching transistor 1 is in the cut-off state. Correspondingly, the second switching transistor 2 is in the conducting state.

[0060] Meanwhile, for the fifth switching period of the third switching transistor 3 shown in the figure, the controller determines to input a low level to the third switching transistor 3, and the third switching transistor 3 is in the cut-off state. Correspondingly, the fourth switching transistor 4 is in the conducting state. The bidirectional power H-bridge topology circuit in this state is denoted as the first state.

[0061] As Figure 4 shown ( Figure 4 is Figure 1 the equivalent circuit diagram in the first state), the AC source 6, the inductor 5, the second switching transistor 2, and the fourth switching transistor 4 are connected in series to form a closed loop. Since the alternating current is about to pass through the zero crossing, the potential difference across the inductor 5 is close to 0, and the current flowing through the inductor 5 is very small.

[0062] (2) Refer to Figure 2 , for the fifth switching period of the first switching transistor 1 shown in the figure, when the PWM count value at the falling edge drops to 10, the controller determines to input a high level to the first switching transistor 1, and the first switching transistor 1 is in the conducting state. Correspondingly, the second switching transistor 2 is in the cut-off state. For the sixth switching period of the first switching transistor 1 shown in the figure, since the PWM comparison value applied in the fifth switching period is 950, before the PWM count value at the rising edge rises to 950, the controller determines to input the original level, that is, a high level, to the first switching transistor 1, and the first switching transistor 1 is in the conducting state. Correspondingly, the second switching transistor 2 is in the cut-off state.

[0063] Meanwhile, for the fifth switching period of the third switching transistor 3 shown in the figure, before the PWM count value at the falling edge drops to 0, the controller determines to input a low level to the third switching transistor 3. At the start of the sixth switching period, since the PWM comparison value 1000 applied in the fifth switching period has been loaded, in the sixth switching period, before the PWM count value at the rising edge rises to 1000, the controller determines to input a low level to the third switching transistor 3, and the third switching transistor 3 is in the cut-off state. Correspondingly, the fourth switching transistor 4 is in the conducting state. The bidirectional power H-bridge topology circuit in this state is denoted as the second state.

[0064] As Figure 5 shown( Figure 5 is Figure 1 the equivalent circuit diagram in the second state), the AC source 6, the inductor 5, the first switching transistor 1, the DC source 7, and the fourth switching transistor 4 are connected in series to form a closed loop. Since the alternating current is about to pass through zero, the potential of the first end 5a of the inductor is close to 0, while the potential of the second end 5b of the inductor is close to 310V. This makes the potential difference across the inductor 5 very large, so the current flowing through the inductor 5 is also very large.

[0065] It can be seen that, as Figure 2 shown, in the shaded part corresponding to the PWM waveform input to the first switching transistor 1, within the switching period when the alternating current passes through zero in the bidirectional power supply H-bridge topology circuit, there is a difference in the PWM waveforms of the input first switching transistor 1 and the third switching transistor 3 by the controller. This difference causes the bidirectional power supply H-bridge topology circuit to suddenly switch from the first state to the second state, resulting in a sudden increase in the current flowing through the inductor 5. The suddenly increased current flowing through the inductor 5 mentioned above is the harmonic current. The existence of the harmonic current may cause the bidirectional power supply H-bridge topology circuit to overheat and affect the service life of electrical equipment.

[0066] To solve the above technical problems, an embodiment of the present disclosure provides a control method for a bidirectional power supply H-bridge topology circuit. Figure 6 FIG. is a flowchart of a control method for a bidirectional power supply H-bridge topology circuit provided by an embodiment of the present disclosure. This process can be executed by a controller. Refer to Figure 6 , the process includes:

[0067] 601. Determine whether the switching period to be controlled is the target switching period.

[0068] 602. When the switching period to be controlled is the target switching period, set the pulse width modulation (PWM) comparison value corresponding to the target switching period to the target value.

[0069] 603. Control the PWM fast transistor of the bidirectional power supply H-bridge topology circuit based on the PWM comparison value corresponding to the target switching period.

[0070] Next, the process of the controller controlling the bidirectional power supply H-bridge topology circuit will be introduced in detail:

[0071] In step 601, the controller determines whether the switching period to be controlled is the target switching period.

[0072] Among them, the controller controls the switching transistors of the bidirectional power supply H-bridge topology circuit. Here, it is discussed how the controller controls the PWM fast transistor in the bidirectional power supply H-bridge topology circuit, and the first switching transistor 1 (i.e., the PWM fast transistor upper bridge) is taken as an example.

[0073] Among them, the target switching period is the second switching period before the switching period at the zero-crossing moment of the alternating current in the bidirectional power H-bridge topology circuit, and the controller determines whether the switching period is the target switching period at the start moment of the switching period to be controlled.

[0074] Optionally, the switching period to be controlled can be the switching period at the current moment.

[0075] In implementation, the controller can obtain the required corresponding information at the start moment of the switching period at the current moment, determine whether the switching period where the current moment is located meets the specified conditions according to the corresponding information, and if the conditions are met, directly determine the period where the current moment is located as the target switching period and perform subsequent processing to control the PWM fast tube of the bidirectional power H-bridge topology circuit.

[0076] Optionally, the switching period to be controlled can be the first switching period after the switching period at the current moment.

[0077] In implementation, the controller can obtain the required corresponding information at the start moment of the switching period, determine whether the switching period where the current moment is located meets the specified conditions according to the corresponding information, and if the switching period where the current moment is located meets the specified conditions, determine the next switching period after the period where the current moment is located as the target switching period and control the PWM fast tube of the bidirectional power H-bridge topology circuit during the target switching period.

[0078] In some possible embodiments, the controller determines the phase angle based on the voltage value and determines whether the switching period to be controlled is the target switching period based on the phase angle. As Figure 7 shown, step 601 may include:

[0079] Step 6011, obtain the real-time voltage value of the alternating current in the bidirectional power H-bridge topology circuit.

[0080] Among them, as Figure 8 shown, the real-time voltage value of the alternating current changes periodically in the form of a cosine function. The real-time voltage value of the alternating current can be a value within the range of [-310V, 310V]. When the alternating current passes through the zero-crossing point, the real-time voltage value of the alternating current is 0. In any one switching period, the phase angle of the alternating current gradually increases from 0 to 2π, and the alternating current passes through the zero-crossing point when the phase angle is π / 2 and 3π / 2.

[0081] In implementation, the controller can obtain the real-time voltage value of the alternating current in the bidirectional power H-bridge topology circuit at regular intervals. The time interval between each time the controller obtains the real-time voltage value of the alternating current in the bidirectional power H-bridge topology circuit can be equal to the duration of the switching period of the PWM fast switch. Thus, the controller can associate the real-time voltage value obtained each time with each switching period of the PWM fast switch.

[0082] Step 6012: Determine the first phase angle of the alternating current based on the real-time voltage value.

[0083] Among them, the first phase angle is within the interval [0, 2π].

[0084] In implementation, as Figure 8 shown, within any one switching period, one real-time voltage value corresponds to two phase angles of the alternating current. Taking the real-time voltage value of 0.5V as an example, the two phase angles corresponding to the real-time voltage value of 0.5V are m and n respectively, where m is less than π / 2 and n is greater than 3π / 2. One of the two first phase angles corresponds to a switching period that is before the switching period where the alternating current zero-crossing moment is located, and it may be the target switching period. The other corresponds to a switching period that is after the switching period where the alternating current zero-crossing moment is located, and it cannot be the target switching period. It can be seen that the controller cannot directly determine the first phase angle of the alternating current through the real-time voltage value and subsequent processing is still required.

[0085] Furthermore, the controller can include a SOGI (Second Order Generalized Integrator) and a phase-locked loop. The controller obtains the real-time voltage value of the alternating current, and then the controller can determine the first phase angle of the alternating current through the SOGI and the phase-locked loop.

[0086] Figure 9 is a schematic structural diagram of a SOGI and a phase-locked loop shown in an embodiment of the present disclosure. The input value of the SOGI phase-locked loop is the obtained real-time voltage value of the alternating current, denoted as V α .

[0087] Among them, is the angle between the alternating current input voltage V (peak value) and the rectangular coordinate system α, and V is the peak value of the alternating current voltage.

[0088] (a) According to the park transformation, the inputs of the park transformation include V α , V β and θ.

[0089] It can be obtained that: V d = V α cosθ + V β sinθ, Vq = V α sinθ - V β cosθ;

[0090] Wherein, V q and V d are the voltage vector components of the rotating rectangular coordinate system, and the angle between them and the grid voltage vector is is the actual phase angle of the alternating current, and θ is the unknown quantity set to be obtained for.

[0091] (b) From the above formula, it can be obtained that:

[0092] (c) After conversion by trigonometric function formulas:

[0093] (d) Making equal to θ, V d = V, V q = 0. Based on this, in the SOGI phase-locked loop, V q = 0 can be used as the basis for closed-loop control. That is, using the output value phase angle θ of the previous switching period as the input value phase angle θ of the next switching period. When V q is close enough to 0, the output phase angle θ is considered to be the first phase angle of the alternating current.

[0094] Exemplarily, the input value phase angle θ of the initial switching period can be π. When V q satisfies being less than 0.05, the output phase angle θ is considered to be the first phase angle of the alternating current.

[0095] Step 6013: Based on the first phase angle of the alternating current, determine whether the switching period to be controlled is the target switching period.

[0096] Specifically, for the controller to determine whether the switching period to be controlled is the target switching period based on the first phase angle of the alternating current, it may include:

[0097] Determine whether the switching period to be controlled is the target switching period when the first phase angle and the second phase angle meet the specified conditions.

[0098] Wherein, the second phase angle is the phase angle of the alternating current determined based on the real-time voltage value of the alternating current in the bidirectional power supply H-bridge topology circuit obtained in the previous switching period.

[0099] Wherein, the specified condition is: θ 2 < (0.5π - T) < θ 1 or θ 2 < (1.5π - T) < θ1 , θ 1 is the first phase angle, and θ 2 is the second phase angle. T is a specified value, and T can be an interval value, which is used to represent the value range of the difference between the phase angle corresponding to the second switching period before the zero-crossing moment of the alternating current and the phase angle at the zero-crossing moment.

[0100] Optionally, T is within the interval (150Xπ, 250Xπ].

[0101] Wherein, X is the duration of the switching period of the first switching transistor 1.

[0102] In implementation, for the third switching transistor 3, the change frequency of its input level is equal to the frequency of the alternating current, both being 50Hz. That is, the phase angle of the alternating current will gradually increase from 0 to 2π within 0.02s. Assuming that the duration of each switching period of the first switching transistor 1 is X, then it is easy to obtain that for each complete switching period duration of the first switching transistor 1, the phase angle of the alternating current will increase by 100Xπ.

[0103] Furthermore, the controller directly determines whether the switching period to be controlled is the second switching period before the zero-crossing moment of the alternating current according to the calculated first phase angle θ 1 If so, it determines that the switching period to be controlled is the target switching period.

[0104] Reference Figure 3 , at the middle moment of the sixth switching period in the figure, the alternating current passes through zero. And the fourth switching period in the figure is the second switching period before the zero-crossing moment of the alternating current. The interval duration from the start moment of the fourth switching period to the zero-crossing moment is the longest, and this maximum interval duration is 2.5 times the duration of the switching period of the first switching transistor 1. The interval duration from the end moment of the fourth switching period to the zero-crossing moment is the shortest, and this minimum interval duration is 1.5 times the duration of the switching period of the first switching transistor 1. Based on this, it can be determined that in this example, T is the phase angle change value corresponding to the duration of 1.5 to 2.5 switching periods of the first switching transistor 1, that is, T is within the interval (150Xπ, 250Xπ].

[0105] It is easy to understand that referring to Figure 3 , for the first switching transistor 1, when T is within the interval (150Xπ, 250Xπ], θ 2 <(0.5π - T) < θ 1 indicates that the second phase angle θ 2 is less than the phase angle of the alternating current corresponding to the start moment of the fourth switching period, and the moment part corresponding to the second phase angle θ 2 is within the fourth switching period. And the first phase angle θ1 is greater than or equal to the phase angle of the alternating current corresponding to the start time of the fourth switching period, and the first phase angle θ 1 is less than the phase angle of the alternating current corresponding to the start time of the fifth switching period. Therefore, the switching period corresponding to the first phase angle θ 1 can be determined as the target switching period. When the phase angle of the alternating current is equal to 1.5π, the principle of the controller for determining the target switching period can refer to the above, and will not be elaborated here.

[0106] Exemplarily, when the frequency of the PWM fast switch is 50 kHz, T is in the interval (3π / 1000, 5π / 1000].

[0107] Optionally, T is in the interval (250Xπ, 350Xπ].

[0108] In implementation, the controller directly determines whether the switching period to be controlled is the third switching period before the switching period where the alternating current zero-crossing moment is located according to the calculated first phase angle θ 1 If so, the next switching period to be controlled is determined as the target switching period.

[0109] Refer to Figure 3 , at the middle moment of the sixth switching period in the figure, the alternating current zero-crosses. And the third switching period in the figure is the third switching period before the switching period where the alternating current zero-crossing moment is located. The interval duration from the start time of the third switching period to the zero-crossing moment is the longest, and this maximum interval duration is the duration of 3.5 switching periods. The interval duration from the end time of the third switching period to the zero-crossing moment is the shortest, and this minimum interval duration is the duration of 2.5 switching periods. Based on this, it can be determined that in this example, T is the phase angle change value corresponding to the duration of 2.5 to 3.5 switching periods, that is, T is in the interval (250Xπ, 350Xπ].

[0110] It is easy to understand that referring to Figure 3 , for the first switching tube 1, when T is in the interval (250Xπ, 350Xπ], θ 2 <(0.5π - T)<θ 1 , which indicates that the second phase angle θ 2 is less than the phase angle of the alternating current corresponding to the start time of the third switching period. And the first phase angle θ 1 is greater than or equal to the phase angle of the alternating current corresponding to the start time of the third switching period, and the first phase angle θ 1 is less than the phase angle of the alternating current corresponding to the start time of the fourth switching period. Therefore, the switching period corresponding to the first phase angle θ 1 can be determined as the third switching period before the switching period where the alternating current zero-crossing moment is located, and the first phase angle θ1 The next switching period corresponding to the corresponding switching period is determined as the target switching period. When the AC phase angle is equal to 1.5π, the principle of the controller for determining the target switching period can be referred to the above, and will not be elaborated here.

[0111] Exemplarily, when the frequency of the PWM fast switch is 50 kHz, T is in the interval (5π / 1000, 7π / 1000].

[0112] Step 602, when the switching period to be controlled is the target switching period, set the pulse width modulation PWM comparison value corresponding to the target switching period as the target value.

[0113] Wherein, the target value is the lower limit of the value range of the PWM count value.

[0114] Referring to the above exemplary content, the lower limit of the value range of the PWM count value can be 0, and the upper limit of the value range of the PWM count value can be 1000.

[0115] In implementation, for the switching period to be controlled, the controller will first determine whether the switching period to be controlled is the target switching period: if it is, the controller will directly determine that the PWM comparison value corresponding to the switching period to be controlled is the lower limit of the value range of the PWM count value. In this example, that is, determine that the PWM comparison value corresponding to the switching period to be controlled is 0; if not, the controller will calculate the PWM comparison value according to the load condition of the bidirectional power H-bridge topology circuit, and the PWM comparison value calculated by the controller according to the load condition may be any value within [0, 1000].

[0116] Further, referring to Figure 3 , when the first switching period to the third switching period are used as the switching period to be controlled, the controller determines whether the first switching period to the third switching period are the target switching period respectively, and the determination results are all negative. Furthermore, for the first switching period to the third switching period, the controller determines the PWM comparison value according to the corresponding load condition respectively. As Figure 3 shown, the PWM comparison value of the first switching period is 13, the PWM comparison value of the first switching period is 12, and the PWM comparison value of the first switching period is 11. Subsequently, when the fourth switching period is used as the switching period to be controlled, the controller determines whether it is the target switching period, and the determination result is positive. Furthermore, for the fourth switching period, the controller sets the PWM comparison value corresponding to the fourth switching period as 0.

[0117] Step 603, based on the PWM comparison value corresponding to the target switching period, control the PWM fast switch of the bidirectional power H-bridge topology circuit.

[0118] Next, a detailed introduction will be given to how the present disclosure solves the principle of generating harmonic current in related technologies:

[0119] As Figure 2 shown, the six switching cycles applied in the figure are 13, 12, 11, 10, 950, 949, and 948 respectively. During the Figure 2 sixth switching cycle in Figure 2 , the alternating current passes through the zero point in the bidirectional power H-bridge topology circuit. Correspondingly, during the

[0120] (1) Referring to Figure 2 , the controller determines that the fourth switching cycle in the figure is the target switching cycle of the first switching tube 1, and sets the PWM comparison value corresponding to the fourth switching cycle to 0. This PWM comparison value is loaded at the start time of the fifth switching cycle in the figure, and the PWM comparison value corresponding to the fifth switching cycle is set to 950. This PWM comparison value is loaded at the start time of the sixth switching cycle in the figure. For the fifth switching cycle of the first switching tube 1 shown in the figure, before the PWM count value at the falling edge drops to 0, the controller determines to input a low level to the first switching tube 1, and the first switching tube 1 is in the cut-off state. Correspondingly, the second switching tube 2 is in the conducting state.

[0121] Meanwhile, for the fifth switching cycle of the third switching tube 3 shown in the figure, the controller determines to input a low level to the third switching tube 3, and the third switching tube 3 is in the cut-off state. Correspondingly, the fourth switching tube 4 is in the conducting state. The bidirectional power H-bridge topology circuit in this state is denoted as the first state.

[0122] As Figure 4 shown ( Figure 4 is Figure 1 the equivalent circuit diagram in the first state), the AC source 6, the inductor 5, the second switching tube 2, and the fourth switching tube 4 are connected in series to form a closed loop. Since the alternating current is about to pass through the zero point, the potential difference across the inductor 5 is close to 0, and the current flowing through the inductor 5 is very small.

[0123] (2) Referring to Figure 3 , for the start time of the sixth switching cycle of the first switching tube 1 shown in the figure, since the PWM comparison value applied in the fifth switching cycle is loaded, the PWM comparison value is replaced from 0 to 950. Until the PWM count value at the rising edge rises to 950, the controller determines to input the original level, that is, the low level, to the first switching tube 1, and the first switching tube 1 is in the cut-off state. Correspondingly, the second switching tube 2 is in the conducting state.

[0124] Meanwhile, for the sixth switching cycle of the third switching transistor 3 shown in the figure, at the start time of the sixth switching cycle, since the PWM comparison value 1000 applied in the fifth switching cycle has been loaded, within the sixth switching cycle, before the PWM count value rises to 950 at the rising edge, the controller determines to input a low level to the third switching transistor 3, and the third switching transistor 3 is in the cut-off state. Correspondingly, the fourth switching transistor 4 is in the conducting state. At this time, the bidirectional power H-bridge topology circuit still maintains the first state.

[0125] It can be seen that based on the PWM comparison value corresponding to the target switching cycle (i.e., the lower limit of the value of the PWM count value), the PWM fast transistor of the bidirectional power H-bridge topology circuit is controlled within the target switching cycle. Comparing Figure 2 and Figure 3 , it can make the PWM waveforms input to the first switching transistor 1 and the third switching transistor 3 by the controller tend to be consistent, thereby avoiding the sudden switching of the bidirectional power H-bridge topology circuit between the first state and the second state, and further avoiding the generation of harmonic current and improving the service life of the electrical equipment.

[0126] Based on the same concept, the embodiment of the present disclosure also provides a control system for a bidirectional power H-bridge topology circuit, and the control system for the bidirectional power H-bridge topology circuit is used to implement the above-provided control method.

[0127] The control system for the bidirectional power H-bridge topology circuit includes a data acquisition unit, a data processing unit, and a switch control unit. Among them, the data processing unit is used to determine the PWM comparison value according to the actual state of the load, and the data acquisition unit is used to acquire the real-time voltage value of the alternating current in the bidirectional power H-bridge topology circuit. The data processing unit will determine the first phase angle and the second phase angle of the alternating current according to the real-time voltage value.

[0128] Based on the same concept, the embodiment of the present disclosure also provides an electrical equipment, and the electrical equipment includes the above-provided control system for the bidirectional power H-bridge topology circuit.

[0129] Among them, the electrical equipment can be, for example but not limited to, an active bidirectional power supply, a charging pile, or a charging module of various energy storage devices.

[0130] It should be noted that the terms used here are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used here, 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 "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0131] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present disclosure. At the same time, it should be understood that, for the sake of convenience in description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the specification. In all the examples shown and discussed here, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, further discussion thereof in subsequent drawings is not required.

[0132] In the description of the present disclosure, it should be understood that the orientation or positional relationships indicated by orientation terms such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom", etc. are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description. Without contrary statements, these orientation terms do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present disclosure; the orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0133] For the convenience of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above" can be used here to describe the spatial positional relationships of a device or feature shown in the drawings with other devices or features. It should be understood that the spatial relative terms are intended to cover different orientations in use or operation in addition to the orientation described in the drawings of the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned as "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations will be made for the spatial relative descriptions used here.

[0134] In addition, it should be noted that the use of terms such as "first", "second" to limit components is only for the convenience of distinguishing the corresponding components. Without additional statements, the above terms have no special meanings, and thus should not be construed as limiting the protection scope of the present disclosure.

[0135] The foregoing are only preferred embodiments of the present disclosure and are not intended to limit the present disclosure. For those skilled in the art, various modifications and variations can be made to the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A control method for a bidirectional power supply H-bridge topology circuit, characterized in that: The method comprises: Determine whether the switching cycle to be controlled is a target switching cycle, wherein the target switching cycle is the second switching cycle before the switching cycle at which the alternating current crosses zero in the bidirectional power supply H-bridge topology circuit; In a case where the switching period to be controlled is the target switching period, setting the pulse width modulation (PWM) comparison value corresponding to the target switching period as a target value, wherein the target value is a lower limit of the PWM count value; Based on the PWM comparison value corresponding to the target switching period, the PWM fast tube of the bidirectional power supply H-bridge topology circuit is controlled.

2. The method according to claim 1, characterized in that: The step of determining whether the switching cycle to be controlled is a target switching cycle includes: Obtaining a real-time voltage value of the alternating current in the bidirectional power supply H-bridge topology circuit; determining a first phase angle of the alternating current based on the real-time voltage value; Based on the first phase angle of the alternating current, it is determined whether the switching cycle to be controlled is a target switching cycle.

3. The method according to claim 2, characterized in that The determining, based on the first phase angle of the alternating current, whether the switching cycle to be controlled is a target switching cycle comprises: In the case where the first phase angle and the second phase angle meet the specified conditions, it is determined whether the switching cycle to be controlled is the target switching cycle, wherein the second phase angle is a phase angle of the alternating current determined based on the real-time voltage value of the alternating current in the bidirectional power supply H-bridge topology circuit obtained in the previous switching cycle, and the specified conditions are: or θ1 is the first phase angle, θ2 is the second phase angle, and T is a specified value.

4. The method according to claim 3, characterized in that: The specified value T is within the interval of (150Xπ, 250Xπ], where X is the duration of the switching cycle of the PWM fast tube.

5. The method according to claim 3, characterized in that: The specified value T is within the interval of [250Xπ, 350Xπ], where X is the duration of the switching cycle of the PWM fast tube.

6. The method according to claim 1, characterized in that The switching cycle to be controlled is the switching cycle at the current moment.

7. The method according to claim 1, characterized in that The switching cycle to be controlled is the first switching cycle after the switching cycle at the current moment.

8. The method according to claim 1, characterized in that: The lower limit of the PWM count value is 0.

9. A bidirectional power supply H-bridge topology circuit control system, characterized in that: The bidirectional power supply H-bridge topology circuit control system is used to implement the control method described in any one of claims 1 to 8.

10. An electrical device, characterized in that: The electrical device includes the bidirectional power supply H-bridge topology circuit control system as described in claim 9.

Images