Single three-phase compatible soft start method, device and rectifier circuit

Abstract

The application relates to the technical field of power systems, and discloses a single three-phase compatible soft-start method, a device and a rectifier circuit. The soft-start method comprises the following steps: setting a soft-start function input parameter based on the topology type of the rectifier circuit; the soft-start function input parameter comprises a soft-start step, an initial turn-on angle and an initial turn-off angle; placing a thyristor of the rectifier circuit at the initial turn-on angle and the initial turn-off angle; and step by step reducing the turn-on angle of the thyristor according to the soft-start step until the direct-current bus voltage of the rectifier circuit reaches a target value or the turn-on angle of the thyristor reaches a target value.

Description

Technical Field

[0001] This application relates to the field of power system technology, specifically to a single-phase and three-phase compatible slow-start method, device, and rectifier circuit. Background Technology

[0002] In power electronic systems, the DC bus, as a core component for energy transmission, directly affects the normal operation of the entire system due to its voltage stability. Especially during system startup, rapid changes in the DC bus voltage can lead to drastic fluctuations in the bus capacitor current. This can not only cause impact damage to power electronic devices but also trigger system instability. Therefore, effectively avoiding current surges caused by sudden changes in DC bus voltage has become one of the key issues urgently needing to be addressed in the field of power electronics technology. Summary of the Invention

[0003] In view of this, embodiments of this application provide a single-phase and three-phase compatible soft-start method, apparatus and rectifier circuit, which can smoothly start the thyristors of the rectifier circuit, so that the DC bus voltage output by the rectifier circuit rises smoothly and avoids sudden changes in the DC bus voltage.

[0004] The technical solution of this application embodiment is implemented as follows:

[0005] This application provides a soft-start method applied to a rectifier circuit. The soft-start method includes: setting soft-start function input parameters based on the topology of the rectifier circuit; the soft-start function input parameters include: soft-start step size, initial turn-on angle, initial turn-off angle, phase-locked loop (PLL) phase, and PLL phase change step size; wherein, the PLL phase change step size is used to adjust the PLL phase to be within the time interval between the turn-on angle and the turn-off angle of the thyristor; the PLL phase change step size is obtained by dividing the product of the upper limit of the soft-start PLL angle step size frequency and the soft-start PLL angle step size fluctuation range by the switching frequency of the thyristor; placing the thyristor of the rectifier circuit at the initial turn-on angle and the initial turn-off angle; and gradually decreasing the turn-on angle of the thyristor according to the soft-start step size until the DC bus voltage of the rectifier circuit reaches a target value or the turn-on angle of the thyristor reaches a target value.

[0006] In some embodiments of this application, the topology of the rectifier circuit includes: a single-phase bridge rectifier circuit or a three-phase rectifier circuit; the method for setting the initial turn-on angle includes: setting the initial turn-on angle of the thyristor in the first path of the rectifier circuit as a first initial turn-on angle; according to the topology of the rectifier circuit, sequentially increasing the phase shift angle based on the first initial turn-on angle as the initial turn-on angle of the thyristors in other paths of the rectifier circuit.

[0007] In some embodiments of this application, the method for setting the initial opening angle further includes: adding a margin to the initial opening angle.

[0008] In some embodiments of this application, the method for setting the initial turn-off angle includes: adding an initial pulse width as the initial turn-on angle.

[0009] In some embodiments of this application, the method further includes: setting a target value for the turn-on angle of the thyristor according to the topology of the rectifier circuit.

[0010] In some embodiments of this application, the method for setting the soft-start step size includes: dividing the change in the turn-on angle by the product of the switching frequency of the thyristor and the soft-start time to obtain the soft-start step size; wherein, the change in the turn-on angle is the initial value of the turn-on angle minus the target value of the turn-on angle.

[0011] This application embodiment also provides a thyristor soft-start device applied to a rectifier circuit. The soft-start device includes: a variable setting module configured to set soft-start function input parameters based on the topology type of the rectifier circuit; the soft-start function input parameters include: a soft-start step size, an initial turn-on angle, and an initial turn-off angle; an initialization module configured to set the thyristor of the rectifier circuit to the initial turn-on angle and the initial turn-off angle; and an adjustment module configured to gradually decrease the turn-on angle of the thyristor according to the soft-start step size until the DC bus voltage of the rectifier circuit reaches a target value or the turn-on angle of the thyristor reaches a target value.

[0012] This application embodiment also provides a rectifier circuit, the rectifier circuit including: a controller; the controller is configured to execute the soft-start method as described in the above scheme.

[0013] It is understood that in this embodiment, by controlling the turn-on angle of the thyristor and reducing the turn-on angle step, the thyristor of the rectifier circuit can be smoothly started, thereby allowing the DC bus voltage output by the rectifier circuit to rise smoothly and avoiding sudden changes in the DC bus voltage. Furthermore, the soft-start method provided in this application is applicable to various rectifier circuits. The input parameters of the soft-start function are set according to the topology of the rectifier circuit, thus enabling corresponding soft-start for different rectifier circuit topologies, broadening the scope of application and improving the soft-start effect. Attached Figure Description

[0014] Figure 1 A flowchart illustrating the soft-start method provided in this application embodiment;

[0015] Figure 2 A schematic diagram of the topology of a single-phase bridge rectifier circuit provided in an embodiment of this application;

[0016] Figure 3 A schematic diagram showing the change in turn-on angle and DC bus voltage during the soft start-up process of a single-phase bridge rectifier circuit provided in this application embodiment;

[0017] Figure 4 A schematic diagram of drive modulation during the soft start-up process of a single-phase bridge rectifier circuit provided in an embodiment of this application. Figure 1 ;

[0018] Figure 5 A schematic diagram illustrating the actual phase-locked loop phase adjustment provided in this application embodiment;

[0019] Figure 6 A schematic diagram of drive modulation during the soft start-up process of a single-phase bridge rectifier circuit provided in an embodiment of this application. Figure 2 ;

[0020] Figure 7 Schematic diagram of the topology of the three-phase rectifier circuit provided in the embodiments of this application Figure 1 ;

[0021] Figure 8 Schematic diagram of drive modulation of a three-phase rectifier circuit during soft start-up provided in an embodiment of this application. Figure 1 ;

[0022] Figure 9 Schematic diagram of drive modulation of a three-phase rectifier circuit during soft start-up provided in an embodiment of this application. Figure 2 ;

[0023] Figure 10 A schematic diagram illustrating the switching angle and DC bus voltage change of the three-phase rectifier circuit provided in this application embodiment during the soft start-up process. Figure 1 ;

[0024] Figure 11 Schematic diagram of the topology of the three-phase rectifier circuit provided in the embodiments of this application Figure 2 ;

[0025] Figure 12 Schematic diagram of drive modulation of a three-phase rectifier circuit during soft start-up provided in an embodiment of this application. Figure 3 ;

[0026] Figure 13 A schematic diagram illustrating the switching angle and DC bus voltage change of the three-phase rectifier circuit provided in this application embodiment during the soft start-up process. Figure 2 ;

[0027] Figure 14This is a schematic diagram of the structure of the soft-start device provided in the embodiments of this application;

[0028] Figure 15 This is a schematic diagram of the rectifier circuit provided in an embodiment of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application are further described in detail below with reference to the accompanying drawings and embodiments. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0031] If the application documents contain similar descriptions such as "first / second", the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific order of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0033] It should be noted that a rectifying circuit is a circuit that converts alternating current (AC) energy into direct current (DC) energy, thereby providing DC bus voltage.

[0034] A rectifier circuit may include a thyristor (Silicon Controlled Rectifier, SCR). By controlling the thyristor, the output of the rectifier circuit can be controlled. However, if the thyristor conducts too quickly, it will cause a sharp change in the DC bus voltage, resulting in a large fluctuation in the bus capacitor current.

[0035] This application provides a soft-start method, such as... Figure 1 As shown, the soft start method includes steps S101 to S103. Each step will be explained in detail below.

[0036] S101. Based on the topology of the rectifier circuit, set the input parameters of the soft start function; the input parameters of the soft start function include: soft start step size, initial turn-on angle and initial turn-off angle.

[0037] In this embodiment, a corresponding function can be called to control the thyristor of the rectifier circuit to achieve soft start of the thyristor.

[0038] For example, you can add the data structure file for the soft start to your project; then, you can declare the corresponding structure in the application's file; and then, you can call the soft start function algorithm within the corresponding function of the application. The macro definitions can be found in the soft start data structure file and modified as needed.

[0039] In this embodiment, to ensure the normal operation of the soft start function, some variables need to be assigned values ​​in real time; that is, the input parameters of the soft start function need to be set. Within the function, soft start-related variables can be uniformly placed in a structure, while enable variables and other parameters can be assigned values ​​as formal parameters of the function. The input parameters of the soft start function need to be set based on the topology of the rectifier circuit. The topology of the rectifier circuit can include: a single-phase bridge rectifier circuit, or a three-phase rectifier circuit; the three-phase rectifier circuit can further include: a three-phase connected neutral (N-line) rectifier circuit, or a three-phase unconnected neutral (N-line) rectifier circuit.

[0040] Refer to Tables 1 and 2 below, where Table 1 shows the input parameters of the soft-start function and Table 2 shows the output parameters of the soft-start function.

[0041] Table 1

[0042]

[0043] Referring to Table 1, the input parameters of the soft start function may include: soft start enable flag bScrBufferEn, phase-locked loop phase f32Theta, phase-locked loop phase change step size f32DeltaTheta, soft start step size f32DeltaStep, and phase shift angle f32PhaseShiftTheta.

[0044] The soft-start enable flag, bScrBufferEn, is used to initiate the soft-start procedure. The phase-locked loop (PLL) phase change step size, f32DeltaTheta, is used to adjust the PLL phase, f32Theta. The soft-start step size, f32DeltaStep, serves as the unit adjustment amount for the thyristor's turn-on angle. The phase shift angle, f32PhaseShiftTheta, characterizes the thyristor's trigger delay angle.

[0045] Table 2

[0046]

[0047] Referring to Table 2, the output parameters of the soft-start function may include: the thyristor drive enable flag bScrEn[CIRCLE_CNT]. The drive enable flag bScrEn[CIRCLE_CNT] represents the thyristor drive control signal.

[0048] In some embodiments of this application, the soft-start step size f32DeltaStep is the change in the turn-on angle divided by the product of the thyristor's switching frequency and the soft-start time; that is, soft-start step size = change in turn-on angle / (thyristor switching frequency * soft-start time). Here, the change in turn-on angle is the initial value of the turn-on angle minus the target value. Thus, the soft-start step size f32DeltaStep can be calculated based on the initial value of the turn-on angle, the target value of the turn-on angle, the thyristor's switching frequency, and the soft-start time, and the corresponding soft-start function input parameters can be set.

[0049] In some embodiments of this application, the phase-locked loop phase change step size f32DeltaTheta is used to adjust the phase-locked loop phase f32Theta to be within the time interval between the thyristor's turn-on angle and turn-off angle.

[0050] It should be noted that a phase-locked loop (PLL) can precisely control the start point of the conduction angle of the thyristor drive signal pulse in the rectifier circuit by tracking the phase changes of the mains voltage or load current in real time. If the PLL phase is earlier than the thyristor's turn-on angle, the thyristor drive signal pulse cannot form an effective conduction path, leading to triggering failure or unstable conduction. If the PLL phase lags behind the thyristor's turn-off angle, the thyristor has already entered the reverse recovery period, and triggering at this time will cause the freewheeling diode to break down in reverse. Therefore, the PLL phase needs to be within the time interval between the thyristor's turn-on and turn-off angles to ensure the formation of the thyristor drive signal pulse.

[0051] In practical applications, refer to Figure 5 The actual maximum phase value θmax of the phase-locked loop (PLL) may not fall within the time interval between the turn-on angle ton and the turn-off angle toff. Therefore, this embodiment of the application adjusts the PLL phase by setting the PLL phase change step size Δθ, so that the PLL phase falls within the time interval between the turn-on angle ton and the turn-off angle toff.

[0052] In some embodiments of this application, the phase-locked loop (PLL) phase change step size f32DeltaTheta is the product of the upper limit of the phase-locked loop angle step frequency and the fluctuation range of the phase-locked loop angle step, divided by the switching frequency of the thyristor. That is, the PLL phase change step size = (upper limit of phase-locked loop angle step frequency * fluctuation range of the phase-locked loop angle step) / switching frequency of the thyristor. Thus, the PLL phase change step size f32DeltaTheta can be set according to the upper limit of the phase-locked loop angle step frequency, the fluctuation range of the phase-locked loop angle step, and the switching frequency of the thyristor.

[0053] In some embodiments of this application, the phase shift angle f32PhaseShiftTheta can be set according to the topology of the rectifier circuit. For example, for a single-phase bridge rectifier circuit, the phase shift angle is set to PI; for a three-phase rectifier circuit, the phase shift angle is set to 2 / 3*PI.

[0054] S102. Set the thyristors of the rectifier circuit to the initial turn-on angle and the initial turn-off angle.

[0055] S103. According to the soft start step size, gradually decrease the turn-on angle of the thyristor until the DC bus voltage of the rectifier circuit reaches the target value or the turn-on angle of the thyristor reaches the target value.

[0056] In this embodiment, after setting the input parameters of the soft-start function, the DSP (Digital Signal Processor) sends a drive signal to the thyristor of the rectifier circuit according to the input parameters of the soft-start function to control the thyristor to perform soft start.

[0057] During the process of controlling the thyristor to perform a soft start, firstly, the thyristor is set to the initial turn-on angle and the initial turn-off angle. At this time, the DC bus voltage output by the rectifier circuit is very small or 0. Then, the turn-on angle of the thyristor can be gradually reduced according to the soft start step size, so that the pulse of the thyristor drive signal gradually increases, thereby making the DC bus voltage output by the rectifier circuit rise smoothly until the DC bus voltage reaches the target value or the turn-on angle of the thyristor reaches the target value.

[0058] It is understood that, in the embodiments of this application, by controlling the turn-on angle of the thyristor and reducing the turn-on angle step, the thyristor of the rectifier circuit can be started smoothly, thereby enabling the DC bus voltage output by the rectifier circuit to rise smoothly and avoiding sudden changes in the DC bus voltage.

[0059] Meanwhile, the soft-start method provided in this application is applicable to a variety of rectifier circuits. The input parameters of the soft-start function are set according to the topology type of the rectifier circuit, so that the soft start can be performed according to the topology type of the rectifier circuit, which broadens the scope of application and improves the effect of soft start.

[0060] It should be noted that the soft-start method provided in this application embodiment can be applied to various rectifier circuits, such as single-phase bridge rectifier circuits and three-phase rectifier circuits. The following description will focus on different rectifier circuits.

[0061] In some embodiments of this application, the soft-start method is applied to a single-phase bridge rectifier circuit. The following description focuses on a single-phase bridge rectifier circuit.

[0062] refer to Figure 2 In a single-phase bridge rectifier circuit, the digital signal processor (DSP) controls four thyristors VT1, VT2, VT3, and VT4 through two pins, GPIO1 and GPIO2. GPIO1 controls thyristors VT1 and VT4, forming the first path; GPIO2 controls thyristors VT2 and VT3, forming the second path. When the AC voltage is in the positive half-cycle, thyristors VT1 and VT4 conduct after the electrical angle reaches the trigger angle; subsequently, when the AC voltage changes to the negative half-cycle, VT1 and VT4 naturally turn off. Similarly, when the AC voltage is in the negative half-cycle, thyristors VT2 and VT3 conduct after the electrical angle reaches the trigger angle; subsequently, when the AC voltage changes to the positive half-cycle, VT2 and VT3 naturally turn off.

[0063] In this embodiment of the application, combined with Figure 3 and Figure 4 The initial turn-on angle of the thyristors in the first path of the rectifier circuit can be set as the first initial turn-on angle. For example, the initial turn-on angle of thyristors VT1 and VT4 in the first path can be set to PI (PI is π). The initial turn-on angle of thyristors VT2 and VT3 in the second path can be obtained by adding the phase shift angle PI to the PI point, that is, set to 2PI.

[0064] Furthermore, to ensure that the thyristor will not be turned on at the initial turn-on angle, a margin can be added to the initial turn-on angle. This margin can be 0.1, 0.2, 0.5, 1, 2, etc., and is not limited here. (Reference) Figure 3 A margin of 0.25 can be added to the initial turn-on angle. That is, the initial turn-on angle of thyristors VT1 and VT4 in the first path is set to PI + 0.25, and the initial turn-on angle of thyristors VT2 and VT3 in the second path is set to 2PI + 0.25. In this way, in the interval 0 < t ≤ t0, the DC bus voltage is 0, and the thyristors will not be turned on, avoiding premature turn-on of the thyristors due to actual errors.

[0065] In this embodiment of the application, reference is made to Figure 3In a single-phase bridge rectifier circuit, during the thyristor's soft-start process, the thyristor's turn-on angle continuously decreases according to the soft-start step size, and the DC bus voltage (i.e., Figure 2 The voltage VC in the circuit changes with the switching angle.

[0066] refer to Figure 3 At the start of the slow start (i.e., when 0 < t ≤ t0), if the turn-on angle of thyristors VT2 / VT3 is greater than 2PI, or the turn-on angle of thyristors VT1 / VT4 is greater than PI, the DC bus voltage is 0. That is, the turn-on angles of thyristors VT1, VT2, VT3, and VT4 are all set to their initial values. When t0 < t ≤ t1, the turn-on angle of thyristors VT2 / VT3 decreases to below 2PI, or the turn-on angle of thyristors VT1 / VT4 decreases to below PI. At this time, the DC bus voltage slowly rises. When t1 < t < t2, the turn-on angle of thyristors VT1 / VT4 decreases to PI / 2, or the turn-on angle of thyristors VT2 / VT3 decreases to 3PI / 2. At this time, the DC bus voltage reaches the target value Vmax.

[0067] refer to Figure 4 For thyristors in a single-phase bridge rectifier circuit, this embodiment uses a fixed turn-off angle toff while continuously advancing the turn-on angle ton for driving. The time interval between the turn-on angle ton and the turn-off angle toff is compared with the phase of the phase-locked loop to generate a drive signal pulse, thereby continuously widening the pulse width of the drive signal.

[0068] In this embodiment of the application, reference is made to Figure 4 The initial turn-off angle can be obtained by increasing the initial pulse width based on the initial turn-on angle. The initial pulse width can be 0.1, 0.2, 0.5, 1, 2, etc., and is not limited here. For example, the initial turn-on angle and initial turn-off angle of thyristors VT1 / VT4 are PI+0.25 and PI+0.5, respectively, and the initial turn-on angle and initial turn-off angle of thyristors VT2 / VT3 are 2PI+0.25 and 2PI+0.5, respectively. The time interval between the initial turn-on angle and the initial turn-off angle (i.e., the initial pulse width) is 0.25.

[0069] Combination Figure 2 and Figure 5When the turn-on angle of thyristors VT2 / VT3 is less than or equal to 2PI, due to the step size factor, the actual maximum phase value θmax of the phase-locked loop (PLL) may not fall within the time interval between the turn-on angle ton and the turn-off angle toff, thus failing to generate a drive signal waveform near the zero-crossing point of 2PI. To address this issue, during the thyristor drive enable judgment process, a phase change step size Δθ can be added to the PLL phase to ensure that the PLL phase falls within the time interval between the turn-on angle ton and the turn-off angle toff, thereby guaranteeing the generation of the drive signal waveform. In other words, referring to Table 1, the PLL phase f32Theta can be adjusted by using the PLL phase change step size f32DeltaTheta to ensure that the PLL phase f32Theta falls within the time interval between the thyristor's turn-on angle ton and the turn-off angle toff.

[0070] Specifically, by incrementing the phase-locked loop (PLL) phase f32Theta by a PLL phase change step size f32DeltaTheta, the maximum value of the PLL phase f32Theta can exceed 2PI. At this point, the turn-on angle will necessarily be smaller than the PLL phase, thus generating the expected drive signal waveform.

[0071] for Figure 2 The single-phase bridge rectifier circuit shown exhibits a soft-start drive modulation process when the turn-on angle ton of thyristors VT2 / VT3 is less than 2PI. Figure 6 As shown. Reference Figure 6 As the turn-on angle ton of thyristors VT2 / VT3 continuously decreases, the turn-off angle toff becomes the actual maximum phase value of the phase-locked loop plus the phase-locked loop phase change step size f32DeltaTheta, which is limited by the phase-locked loop phase value.

[0072] In some embodiments of this application, the soft-start method is applied to a three-phase rectifier circuit. The following description focuses on a three-phase rectifier circuit.

[0073] Figure 7 The topology of a three-phase rectifier circuit (without the neutral (N) line) is shown. (Reference) Figure 7In a three-phase rectifier circuit (without the neutral (N) line), the digital signal processor (DSP) controls six thyristors VT1, VT2, VT3, VT4, VT5, and VT6 via three pins: GPIO1, GPIO2, and GPIO3. Specifically, GPIO1 controls thyristor VT1 in the upper arm of phase A and thyristor VT6 in the lower arm of phase B, forming the first path; GPIO2 controls thyristor VT3 in the upper arm of phase B and thyristor VT2 in the lower arm of phase C, forming the second path; and GPIO3 controls thyristor VT5 in the upper arm of phase C and thyristor VT4 in the lower arm of phase A, forming the third path.

[0074] In this embodiment of the application, for Figure 7 The three-phase rectifier circuit shown (without the neutral line) exhibits a slow-start drive modulation process as follows when the turn-on angle ton of thyristors VT5 / VT4 is greater than 2PI. Figure 8 As shown. Reference Figure 8 In a three-phase rectifier circuit, the phase shift angles of thyristors VT1 / VT6, thyristors VT3 / VT2, and thyristors VT5 / VT4 are 2PI / 3.

[0075] In this embodiment of the application, for Figure 7 The three-phase rectifier circuit shown (without the neutral line) exhibits the following soft-start drive modulation process when the turn-on angle ton of thyristors VT5 / VT4 is less than 2PI: Figure 9 As shown. Reference Figure 9 When the turn-on angle ton of thyristors VT1 / VT6 crosses commutation point 1 (i.e., the intersection point of the AC voltages of phase A and phase B during the positive half-cycle), thyristor VT1 in the upper arm of phase A and thyristor VT6 in the lower arm of phase B conduct. At this time, although the voltage of phase C in the common anode group is the lowest, there is no drive signal for the lower arm of phase C. When the turn-on angle ton of thyristors VT3 / VT2 crosses commutation point 1, thyristor VT2 in the lower arm of phase C conducts, while thyristor VT6 does not conduct. At this time, the voltage of phase C in the common anode group is the lowest, and there is a drive signal for the lower arm of phase C. Similarly, when the turn-on angle of thyristors VT1 / VT6 crosses the commutation point 2 (i.e., the intersection point of the AC voltages of phase C and phase A in the positive half-cycle), thyristor VT5 of the upper bridge arm of phase C turns on, while thyristor VT1 does not turn on. At this time, the voltage of phase C in the common cathode group is the largest, and there is a drive signal for the upper bridge arm of phase C.

[0076] In this embodiment of the application, combined with Figure 8 and Figure 10The initial turn-on angle of the thyristors in the first path of the rectifier circuit can be set as a first initial turn-on angle. For example, the initial turn-on angle of thyristors VT1 and VT6 in the first path can be set to PI (PI is π). Furthermore, the initial turn-on angle of thyristors VT2 and VT3 in the second path can be obtained by adding a phase shift angle of 2PI / 3 to PI, i.e., set to 5PI / 3. Similarly, the initial turn-on angle of thyristors VT4 and VT5 in the third path can be obtained by adding a phase shift angle of 2PI / 3 to 5PI / 3, i.e., set to 7PI / 3.

[0077] Furthermore, to ensure that the thyristor will not be turned on at the initial turn-on angle, a margin can be added to the initial turn-on angle. (Reference) Figure 10 A margin of 0.25 can be added to the initial turn-on angle. That is, the initial turn-on angle of thyristors VT1 and VT6 in the first path is set to PI + 0.25, the initial turn-on angle of thyristors VT2 and VT3 in the second path is set to 5PI / 3 + 0.25, and the initial turn-on angle of thyristors VT4 and VT5 in the third path is set to 7PI / 3 + 0.25. In this way, in the interval 0 < t ≤ t0, the DC bus voltage is 0, and the thyristors will not be turned on, avoiding premature turn-on of the thyristors due to actual errors.

[0078] In this embodiment of the application, combined with Figure 7 and Figure 5 In a three-phase rectifier circuit (without the neutral (N) line), when the turn-on angle of thyristors VT5 / VT4 is near the 2PI zero-crossing point, it's necessary to consider the possibility that the actual PLL phase maximum value θmax may not reach 2PI. In this case, the actual PLL phase maximum value θmax might not fall within the time interval between ton and toff, thus failing to generate a drive signal waveform near the 2PI zero-crossing point. Therefore, a PLL phase change step size Δθ needs to be added to the PLL phase to ensure that the actual PLL phase maximum value θmax exceeds 2PI, thereby ensuring that the PLL phase falls within the time interval between the turn-on angle ton and the turn-off angle toff, guaranteeing the generation of the drive signal waveform. In other words, referring to Table 1, the PLL phase f32Theta can be adjusted by using the PLL phase change step size f32DeltaTheta to ensure that the PLL phase f32Theta falls within the time interval between the thyristor's turn-on angle ton and turn-off angle toff. Similarly, the turn-off angle toff of thyristors VT5 / VT4 becomes the actual maximum phase of the phase-locked loop plus the phase-locked loop phase change step size f32DeltaTheta.

[0079] refer to Figure 10In a three-phase rectifier circuit (without the neutral line), during the soft-start process of the thyristor, the thyristor's turn-on angle continuously decreases according to the soft-start step size, and the DC bus voltage (i.e., Figure 7 The voltage VC in the circuit changes with the switching angle. The following explanation uses thyristors VT1 / VT6 as an example. Thyristors VT5 / VT4 and VT3 / VT2 also have a similar process.

[0080] refer to Figure 10 When 0 < t ≤ t0, the turn-on angle ton of thyristors VT1 / VT6 is greater than PI, and the DC bus voltage is 0. When t0 < t ≤ t1, the turn-on angle ton of thyristors VT1 / VT6 is less than PI and gradually approaches commutation point 1 (5PI / 6). At this time, all thyristors are still not conducting, and the DC bus voltage is 0. When t1 < t < t2, the turn-on angle ton of thyristors VT1 / VT6 crosses commutation point 1 (5PI / 6), and slow start begins. At this time, the DC bus voltage slowly rises. When t = t2, the turn-on angle ton of thyristors VT1 / VT6 is equal to PI / 3, and the difference between the AC voltages of phase A and phase B (VA-VB) is at its maximum. At this time, the DC bus voltage reaches the target value Vmax. When t2 < t ≤ t3, the DC bus voltage gradually stabilizes after reaching the target value. When t > t3, the slow start of the thyristors in the three-phase rectifier circuit (without the neutral line) ends.

[0081] Figure 11 The topology of a three-phase rectifier circuit (connected to the N-line) is shown. (Reference) Figure 11 In a three-phase rectifier circuit (connected to the neutral (N) line), the digital signal processor (DSP) controls six thyristors VT1, VT2, VT3, VT4, VT5, and VT6 via three pins: GPIO1, GPIO2, and GPIO3. Specifically, GPIO1 controls thyristor VT1 in the upper arm of phase A and thyristor VT6 in the lower arm of phase B, forming the first path; GPIO2 controls thyristor VT3 in the upper arm of phase B and thyristor VT2 in the lower arm of phase C, forming the second path; and GPIO3 controls thyristor VT5 in the upper arm of phase C and thyristor VT4 in the lower arm of phase A, forming the third path.

[0082] for Figure 11 The three-phase rectifier circuit shown (connected to the neutral line) demonstrates a soft-start drive modulation process when the turn-on angle ton of thyristors VT5 / VT4 is greater than 2PI. Figure 8 Related descriptions to the above.

[0083] for Figure 11The three-phase rectifier circuit shown (connected to the neutral line) exhibits a soft-start drive modulation process as follows when the turn-on angle ton of thyristors VT5 / VT4 is less than 2PI. Figure 12 As shown. Reference Figure 12 When the turn-on angle of thyristors VT1 / VT6 just crosses the zero point of phase A, thyristor VT1 of the upper bridge arm of phase A is turned on, and thyristor VT6 of the lower bridge arm of phase B is not turned on; when the turn-on angle of thyristors VT1 / VT6 crosses the zero point of phase B, thyristor VT6 of the lower bridge arm of phase B is turned on.

[0084] In this embodiment of the application, combined with Figure 8 and Figure 13 The initial turn-on angle of the thyristors in the first path of the rectifier circuit can be set as a first initial turn-on angle. For example, the initial turn-on angle of thyristors VT1 and VT6 in the first path can be set to PI (PI is π). Furthermore, the initial turn-on angle of thyristors VT2 and VT3 in the second path can be obtained by adding a phase shift angle of 2PI / 3 to PI, i.e., set to 5PI / 3. Similarly, the initial turn-on angle of thyristors VT4 and VT5 in the third path can be obtained by adding a phase shift angle of 2PI / 3 to 5PI / 3, i.e., set to 7PI / 3.

[0085] Furthermore, to ensure that the thyristor will not be turned on at the initial turn-on angle, a margin can be added to the initial turn-on angle. (Reference) Figure 13 A margin of 0.25 can be added to the initial turn-on angle. That is, the initial turn-on angle of thyristors VT1 and VT6 in the first path is set to PI + 0.25, the initial turn-on angle of thyristors VT2 and VT3 in the second path is set to 5PI / 3 + 0.25, and the initial turn-on angle of thyristors VT4 and VT5 in the third path is set to 7PI / 3 + 0.25. In this way, in the interval 0 < t ≤ t0, the DC bus voltage is 0, and the thyristors will not be turned on, avoiding premature turn-on of the thyristors due to actual errors.

[0086] Combination Figure 11 and Figure 5In a three-phase rectifier circuit (connected to the neutral line), when the turn-on angle of thyristors VT5 / VT4 is near the 2PI zero-crossing point, it's necessary to consider the possibility that the actual PLL phase maximum value θmax may not reach 2PI. In this case, the actual PLL phase maximum value θmax might not fall within the time interval between the turn-on angle ton and the turn-off angle toff, thus failing to generate a drive signal waveform near the 2PI zero-crossing point. Therefore, a PLL phase change step size Δθ needs to be added to the PLL phase to ensure that the actual PLL phase maximum value θmax exceeds 2PI, thereby ensuring that the PLL phase falls within the time interval between the turn-on angle ton and the turn-off angle toff, guaranteeing the generation of the drive signal waveform. In other words, referring to Table 1, the PLL phase f32Theta can be adjusted by using the PLL phase change step size f32DeltaTheta to ensure that the PLL phase f32Theta falls within the time interval between the thyristor's turn-on angle ton and turn-off angle toff. Similarly, the turn-off angle toff of thyristors VT5 / VT4 becomes the actual maximum phase of the phase-locked loop plus the phase-locked loop phase change step size f32DeltaTheta.

[0087] refer to Figure 13 In a three-phase rectifier circuit (connected to the neutral line), during the soft-start process of the thyristor, the thyristor's turn-on angle continuously decreases according to the soft-start step size, and the DC bus voltage (i.e., Figure 11 The voltage VC in the circuit changes with the switching angle. The following explanation uses thyristors VT1 / VT6 as an example. Thyristors VT5 / VT4 and VT3 / VT2 also have a similar process.

[0088] refer to Figure 13 When 0 < t ≤ t0, the turn-on angle ton of thyristors VT1 / VT6 is greater than PI, and the DC bus voltage is 0. When t0 < t ≤ t1, the turn-on angle ton of thyristors VT1 / VT6 is less than PI and gradually approaches the zero-crossing point of phase B, and the DC bus voltage slowly rises. When t1 < t < t2, the turn-on angle ton of thyristors VT1 / VT6 crosses the zero-crossing point of phase B, and thyristor VT6 in the lower arm of phase B conducts, and the DC bus voltage continues to rise. When t = t2, the turn-on angle ton of thyristors VT1 / VT6 is equal to PI / 6, and the target value of phase B reaches its maximum during the negative half-cycle. At this time, the DC bus voltage reaches the target value Vmax. When t2 < t ≤ t3, the DC bus voltage gradually stabilizes after reaching the target value Vmax. When t > t3, the slow start of the thyristors in the three-phase rectifier circuit (connected to the N line) ends.

[0089] refer to Figures 2 to 13The initial preset angle of the thyristor in the preset path of the rectifier circuit is set as the first initial turn-on angle. The preset path is any path in the rectifier circuit. As in the above embodiment, the preset path is the first path, and the first initial turn-on angle is set to π (π is PI). In other embodiments, the first initial turn-on angle can be set according to the topology of the rectifier circuit. When the rectifier circuit is a single-phase bridge rectifier circuit or a three-phase connected N-line rectifier circuit, the first initial turn-on angle is set to π. When the rectifier circuit is a three-phase non-connected N-line rectifier circuit, the first initial turn-on angle is set to π / 6.

[0090] Same reference Figures 2 to 13 In the above embodiments, the DC bus circuit of the rectifier circuit reaching the target value Vmax is used as the basis for determining the end of the soft start. In the above embodiments, the soft start process can also be determined by whether the turn-on angle reaches the target value. Specifically, the target value of the turn-on angle can be set according to the topology of the rectifier circuit. For example, in the above embodiments, for a single-phase bridge rectifier circuit, the target value of the turn-on angle of the preset path is set to π / 2; for a three-phase connected N-line rectifier circuit, the target value of the turn-on angle of the preset path is set to π / 6; and for a three-phase unconnected N-line rectifier circuit, the target value of the turn-on angle of the preset path is set to π / 3.

[0091] This application also provides a thyristor soft-start device, such as... Figure 14 As shown, the soft start device 800 includes: a variable setting module 810, an initialization module 820, and an adjustment module 830.

[0092] The variable setting module 810 is configured to set the input parameters of the soft-start function based on the rectifier circuit topology. These input parameters include: soft-start step size, initial turn-on angle, and initial turn-off angle. The initialization module 820 is configured to set the thyristors of the rectifier circuit to their initial turn-on and initial turn-off angles. The adjustment module 830 is configured to gradually decrease the turn-on angle of the thyristors according to the soft-start step size until the DC bus voltage of the rectifier circuit reaches the target value or the turn-on angle of the thyristors reaches the target value.

[0093] In some embodiments of this application, the topology of the rectifier circuit includes: a single-phase bridge rectifier circuit, or a three-phase rectifier circuit.

[0094] In some embodiments of this application, the initialization module 820 is further configured to set the initial turn-on angle of the thyristor in the first path of the rectifier circuit to a first initial turn-on angle; and to sequentially increase the phase shift angle based on the first initial turn-on angle according to the topology of the rectifier circuit, as the initial turn-on angle of the thyristors in other paths of the rectifier circuit.

[0095] In some embodiments of this application, the initialization module 820 is also configured to add a margin to the initial opening angle.

[0096] In some embodiments of this application, the initialization module 820 is further configured to add an initial pulse width as an initial turn-off angle based on the initial turn-on angle.

[0097] In some embodiments of this application, the target value of the thyristor's turn-on angle is set according to the topology of the rectifier circuit.

[0098] In some embodiments of this application, the soft-start step size is the change in the turn-on angle divided by the product of the thyristor's switching frequency and the soft-start time. The change in the turn-on angle is the initial value of the turn-on angle minus the target value of the turn-on angle.

[0099] In some embodiments of this application, the input parameters of the soft-start function further include: phase-locked loop (PLL) phase and PLL phase change step size. The PLL phase change step size is used to adjust the PLL phase to fall within the time interval between the thyristor's turn-on and turn-off angles.

[0100] In some embodiments of this application, the phase-locked loop phase change step size is the product of the upper limit of the slow-start phase-locked loop angle step frequency and the slow-start phase-locked loop angle step fluctuation range, divided by the thyristor switching frequency.

[0101] This application also provides a rectifier circuit, such as... Figure 15 As shown, the rectifier circuit 900 includes a controller 910. The controller is configured to execute the soft-start method as described in the above scheme.

[0102] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0103] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The methods disclosed in the several method embodiments provided in this application can be arbitrarily combined to obtain new method embodiments without conflict. The features disclosed in the several product embodiments provided in this application can be arbitrarily combined to obtain new product embodiments without conflict. The features disclosed in the several method or device embodiments provided in this application can be arbitrarily combined to obtain new method or device embodiments without conflict.

[0104] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A single three-phase compatible soft start method applied to a rectifier circuit, characterized in that, The slow start method comprises: Setting a slow start function input parameter based on the topology type of the rectifier circuit; the slow start function input parameter comprises: a slow start step, an initial turn-on angle, an initial turn-off angle, a phase-locked loop phase, and a phase-locked loop phase change step; wherein the phase-locked loop phase change step is used to adjust the phase-locked loop phase to be within the time interval of the turn-on angle and the turn-off angle of the thyristor of the rectifier circuit; the maximum value of the phase-locked loop phase is greater than 2PI; the phase-locked loop phase change step is the product of the upper limit of the slow start phase-locked angle step frequency and the fluctuation range of the slow start phase-locked angle step divided by the switching frequency of the thyristor; Placing the thyristor of the rectifier circuit at the initial turn-on angle and the initial turn-off angle; According to the slow start step, stepwise reduce the turn-on angle of the thyristor until the DC bus voltage of the rectifier circuit reaches a target value or the turn-on angle of the thyristor reaches a target value; The topology type of the rectifier circuit comprises: a single-phase bridge rectifier circuit, or a three-phase rectifier circuit; The method for setting the initial turn-on angle comprises: setting the initial turn-on angle of the thyristor of the first path in the rectifier circuit as a first initial turn-on angle; increasing the phase shift angle on the basis of the first initial turn-on angle as the initial turn-on angle of the thyristor of other paths in the rectifier circuit according to the topology type of the rectifier circuit; wherein for the single-phase bridge rectifier circuit, the first initial turn-on angle is set to PI; for the three-phase rectifier circuit without N line, the first initial turn-on angle is set to 5 / 6*PI; for the three-phase rectifier circuit with N line, the first initial turn-on angle is set to PI.

2. The soft start method of claim 1, wherein, The method for setting the initial turn-on angle further comprises: Adding a margin to the initial turn-on angle.

3. The soft start method of claim 1, wherein, The method for setting the initial turn-off angle comprises: Increasing the initial pulse width on the basis of the initial turn-on angle as the initial turn-off angle.

4. The soft start method of claim 1, wherein, The method further comprises: Setting the target value of the turn-on angle of the thyristor according to the topology type of the rectifier circuit.

5. The soft start method of claim 1, wherein, The method for setting the slow start step comprises: Dividing the change amount of the turn-on angle by the product of the switching frequency of the thyristor and the slow start time to obtain the slow start step; wherein the change amount of the turn-on angle is the initial value of the turn-on angle minus the target value of the turn-on angle. 6.A slow start device of a thyristor, applied to a rectifier circuit, characterized in that The slow start device is configured to perform the slow start method of any one of claims 1 to 5.

7. A rectifier circuit, characterized by The rectifier circuit comprises a controller; The controller is configured to perform the slow start method of any one of claims 1 to 5.

Images