SOP power module dead zone effect suppression method

Abstract

The invention relates to the field of power electronic converters and control, in particular to an SOP power module dead-zone effect suppression method, which comprises the following steps: acquiring the current transmission power of an SOP power module; based on the transmission power, generating a first bus voltage instruction used for controlling an AC-DC side direct current bus voltage and a second bus voltage instruction used for controlling a DC-AC side direct current bus voltage, adjusting the corresponding direct current bus voltage so as to inhibit polarity reversal of a DAB converter bridge port voltage, and according to the transmission power of the SOP power module, adjusting the polarity of the DAB converter bridge port voltage. A first bus voltage instruction and a second bus voltage instruction are generated, the first bus voltage instruction and the second bus voltage instruction are made to be unequal during light load, a bus voltage difference value is formed, and it is ensured that the direct-current bus voltages on the two sides meet the condition for restraining DAB bridge port voltage polarity reversal in the dead-zone time period by means of compensation for frequency doubling fluctuation components in the direct-current bus voltages. Current zero step is eliminated, soft switching is recovered, voltage stability under light load is improved, extra hardware or complex control is not needed, and engineering realization is simple and convenient.

Description

Technical Field

[0001] This invention relates to the field of power electronic converters and control, and in particular to a method for suppressing the dead-time effect of SOP power modules. Background Technology

[0002] With the large-scale integration of new energy sources, energy storage, and diversified loads, traditional distribution networks are evolving from unidirectional radial passive networks to complex active networks with bidirectional power flow. This transformation brings problems such as voltage fluctuation exceeding limits and uneven power flow distribution, which reduce the stability of the power system and inhibit the improvement of power supply capacity.

[0003] Traditional power distribution networks rely on mechanical switches for passive regulation, which suffers from slow response and low control flexibility, making it difficult to meet the precise control requirements for power quality, reliability, and operational efficiency under the integration of high-penetration renewable energy sources. Smart soft switches (SOPs) offer advantages such as fast control speed, continuously adjustable power flow, shock-free loop closing and opening, and voltage and reactive power support, making them more suitable for areas with high reliability requirements or power grids containing a high proportion of renewable energy, improving power supply continuity and stability. Medium-voltage SOPs employ a modular cascade structure to reduce the withstand voltage of switching devices. The SOP power modules utilize a three-stage conversion structure: AC-DC, DC-DC, and DC-AC. The AC-DC and DC-AC stages use single-phase H-bridge inverters as basic power units, offering modularity and easy expansion, facilitating multi-level output and improving power quality. The DC-DC stage uses a dual active bridge (DAB) converter, achieving not only electrical isolation between the two ports but also, through its inherent soft-switching characteristics and high-frequency power modulation capabilities, enabling efficient, fast, and bidirectional energy transmission.

[0004] In the SOP power module control process, a dead time is required to prevent shoot-through of the same bridge arm switch. However, the dead time affects the operating state of the DAB under light load, causing polarity reversal and voltage drop at the DAB bridge port voltage, known as the dead time effect. The dead time effect disrupts the soft-switching conditions of the DAB, threatens the stability of the DC bus capacitor voltages on both sides, and increases the harmonics of the AC side grid-connected current. Therefore, it is urgent to develop a dead time effect suppression method to suppress the polarity reversal of the DAB bridge port voltage under light load. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to solve the problem that when the SOP power module is running under light load, the voltage polarity reversal and voltage drop of the DAB bridge port caused by the dead time will lead to the interruption of inductor current, damage to soft switching conditions, threat to bus voltage stability and increase grid current harmonics.

[0006] The above-mentioned technical problems are solved by the following technical solution: The present invention proposes a method for suppressing dead-zone effect of SOP power module, which includes obtaining the current transmission power of the SOP power module; Based on the transmission power, a first bus voltage command for controlling the DC bus voltage on the AC-DC side and a second bus voltage command for controlling the DC bus voltage on the DC-AC side are generated. The DC bus voltage on the AC-DC side of the SOP power module is adjusted according to the first bus voltage command, and the DC bus voltage on the DC-AC side of the SOP power module is adjusted according to the second bus voltage command, so as to suppress the polarity reversal of the DAB converter bridge port voltage.

[0007] In a preferred embodiment of the SOP power module dead-time effect suppression method of the present invention: the generation of the first bus voltage command and the second bus voltage command based on the transmission power includes: The transmission power is compared with a preset dead-zone effect suppression threshold, which is the transmission power boundary for determining whether the polarity reversal of the DAB converter bridge port voltage needs to be suppressed. If the transmission power is less than the dead-zone effect suppression threshold, the system is determined to be in a light-load mode. If the transmission power is not less than the dead-zone effect suppression threshold, the system is determined to be in a non-light-load mode.

[0008] In a preferred embodiment of the SOP power module dead zone effect suppression method of the present invention: when the system is in light load mode, a first bus voltage command and a second bus voltage command that are not equal are generated so that the DC bus voltage adjusted by the AC-DC side is not equal to that of the DC-AC side.

[0009] In a preferred embodiment of the SOP power module dead zone effect suppression method of the present invention: when the system is in a non-light load mode, a first bus voltage command and a second bus voltage command that are equal to each other are generated so that the DC bus voltage of the AC-DC side is equal to that of the DC-AC side after adjustment.

[0010] In a preferred embodiment of the SOP power module dead-time effect suppression method of the present invention: the generation of unequal first bus voltage commands and second bus voltage commands includes: Obtain the second harmonic fluctuation component in the DC bus voltage of the SOP power module; The first bus voltage command and the second bus voltage command are compensated based on the second harmonic fluctuation component, so that the actual DC bus voltage on both sides of the SOP power module meets the voltage difference condition required to suppress the polarity reversal of the DAB converter bridge port voltage during the dead time period.

[0011] In a preferred embodiment of the SOP power module dead-time effect suppression method of the present invention: generating unequal first bus voltage commands and second bus voltage commands includes: obtaining the current phase shift angle and dead-time ratio of the DAB converter; determining the minimum bus voltage difference condition required to suppress the polarity reversal of the DAB converter bridge port voltage based on the phase shift angle and dead-time ratio; and setting the relative magnitudes of the first bus voltage command and the second bus voltage command according to the minimum bus voltage difference condition.

[0012] In a preferred embodiment of the SOP power module dead-zone effect suppression method of the present invention: obtaining the current phase shift angle of the DAB converter includes: Obtain the current transmission power of the SOP power module; The phase shift angle of the DAB converter is set according to the transmission power.

[0013] In a preferred embodiment of the SOP power module dead-time effect suppression method of the present invention: obtaining the current dead-time ratio of the DAB converter includes: Read the dead time and switching cycle of the SOP power module; based on the dead time and switching cycle, determine the proportion of the dead time to half a switching cycle, and use it as the dead time proportion.

[0014] In a preferred embodiment of the dead-zone effect suppression method for SOP power modules described in this invention: the SOP power module includes an AC-DC converter, a dual active bridge DAB converter, and a DC-AC converter connected in sequence, wherein both the AC-DC converter and the DC-AC converter adopt a single-phase H-bridge structure.

[0015] In a preferred embodiment of the dead-zone effect suppression method for SOP power modules described in this invention: the second harmonic fluctuation component is generated by the single-phase H-bridge structure on the AC-DC side or DC-AC side of the SOP power module during the power conversion process.

[0016] The beneficial effects of this invention are as follows: Based on the transmission power of the SOP power module, a first bus voltage command and a second bus voltage command are generated. Under light load, the two are made unequal, forming a bus voltage difference. Combined with compensation for the second harmonic fluctuation component in the DC bus voltage, it ensures that the DC bus voltages on both sides meet the condition of suppressing the polarity reversal of the DAB bridge port voltage during the dead time period, eliminating the current zero step, restoring soft switching, and improving the voltage stability under light load. No additional hardware or complex control is required, and the engineering implementation is simple. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Wherein: Figure 1 A schematic diagram of the SOP power module topology is shown; Figure 2 The diagram shows the voltage polarity reversal waveform at the DAB bridge port of the SOP power module. Figure 3 The control block diagram of the SOP power module is shown; Figure 4 The simulation diagram of positive power light load operation under conventional control is shown; Figure 5 The simulation diagram of positive power light load operation using the suppression method of this application is shown; Figure 6 The simulation diagram of negative power light load operation under conventional control is shown; Figure 7 The simulation diagram of negative power light load operation using the suppression method of this application is shown; Figure 8 The simulation diagram of full-load operation under negative power using the suppression method of this application is shown. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0019] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0020] Reference Figures 1-3 This embodiment provides a method for suppressing the dead-time effect of an SOP power module, including: Get the current transmission power of the SOP power module; Based on the transmission power, a first bus voltage command for controlling the DC bus voltage on the AC-DC side and a second bus voltage command for controlling the DC bus voltage on the DC-AC side are generated. The DC bus voltage on the AC-DC side of the SOP power module is adjusted according to the first bus voltage command, and the DC bus voltage on the DC-AC side of the SOP power module is adjusted according to the second bus voltage command, so as to suppress the polarity reversal of the DAB converter bridge port voltage.

[0021] like Figure 1 As shown, the SOP power module adopts a three-stage conversion structure of AC-DC, DC-DC, and DC-AC. The AC-DC and DC-AC conversion stages use single-phase H-bridge converters, with the AC port connected to the power grid to realize energy conversion between AC and DC. The DC-DC stage is a DAB topology, sharing a DC bus with the single-phase H-bridge converters on both sides, thereby realizing energy transfer within the module. The DAB uses a high-frequency transformer to reduce the overall size of the module. Figure 1 The specific components are as follows: T1~T8 are the switching transistors of the H-bridge converter, S1~S8 are the DAB switching transistors; T represents a transformer with a turns ratio n of 1:1; Lt is the transformer leakage inductance; Lg1 and Lg2 are AC side inductors; C1 and C2 are DC bus capacitors; u1 and u2 represent the bus capacitor voltages; iL represents the DAB inductor current, and the arrow in the figure indicates its positive direction; ig1 and ig2 represent AC side currents; ug1 and ug2 represent AC side voltages; uab and ucd represent DAB bridge port voltages.

[0022] like Figure 2 As shown, in the SOP power module, after adding a dead time, the polarity of the DAB bridge port voltage is reversed. Figure 2 In the diagram, uab is the AC output voltage of the DAB bridge port, iL is the current in inductor Lt, Ths is half a switching cycle, M is the proportion of dead time to Ths, and D represents the proportion of phase shift angle within half a switching cycle (0≤D≤1). With the addition of dead time, the duty cycle of the upper and lower switches in the same bridge arm is no longer 50%. This will cause the voltage polarity to reverse and the voltage drop to occur at the DAB bridge port under light load. Furthermore, the DAB current is zero at the voltage drop position, reducing the transmission power of the system. This is because the commutation path of the system changes during the dead time. Therefore, it is necessary to effectively suppress the dead time effect.

[0023] like Figure 3As shown, the dead-zone effect suppression method of this SOP power module is applied to the SOP power module to form a flexible closed-loop device. Specifically, in the AC-DC power loop, the AC voltage ug1, AC current ig1, and bus voltage u1 on the grid 1 side are sampled, and a voltage and current dual closed-loop control strategy is used to achieve stable control of u1 and ig1. In the DC-DC power loop, the bus voltage u2 is sampled, and a voltage closed-loop control strategy is used. The H-bridge switches on the primary and secondary sides operate with a 50% duty cycle, and the stable control of u2 is achieved through single phase shift control on the secondary side. In the DC-AC power loop, the AC voltage ug2 and AC current ig2 on the grid 2 side are sampled, and a power and current dual closed-loop control strategy is adopted to achieve stable control of the system power.

[0024] Specifically, by controlling the bus voltage according to the system's transmission power, the voltage values ​​of the bus capacitors on both sides of the SOP power module are adjusted to form a certain bus voltage difference. While realizing the control of the SOP power module, the polarity reversal and voltage drop of the bus voltage are eliminated. Under light load, a certain voltage difference is formed between the two bus voltages; under heavy load, the voltage values ​​of the two bus voltages are kept equal, thereby effectively suppressing the voltage drop and polarity reversal of the DAB bridge port under light load. This is simple to implement and does not increase the complexity of system control.

[0025] In one embodiment provided in this application, generating a first bus voltage command and a second bus voltage command based on transmission power includes: The transmission power is compared with a preset dead-zone effect suppression threshold, which is the transmission power boundary for determining whether to suppress the polarity reversal of the DAB converter bridge port voltage. If the transmission power is less than the dead-zone effect suppression threshold, the system is determined to be in light-load mode. If the transmission power is not less than the dead-zone effect suppression threshold, the system is determined to be in a non-light-load mode.

[0026] In one embodiment provided in this application, when the system is in a light load mode, a first bus voltage command and a second bus voltage command that are not equal are generated so that the adjusted DC bus voltage on the AC-DC side is not equal to that on the DC-AC side.

[0027] In one embodiment provided in this application, when the system is in a non-light load mode, a first bus voltage command and a second bus voltage command that are equal to each other are generated so that the adjusted DC bus voltage on the AC-DC side is equal to that on the DC-AC side.

[0028] In one embodiment provided in this application, generating a first bus voltage command and a second bus voltage command that are not equal includes the following steps A1-A2: A1: Obtain the second harmonic fluctuation component in the DC bus voltage of the SOP power module; A2: Based on the second harmonic fluctuation component, the first bus voltage command and the second bus voltage command are compensated so that the actual DC bus voltage on both sides of the SOP power module meets the voltage difference condition required to suppress the polarity reversal of the DAB converter bridge port voltage during the dead time period.

[0029] It should be further explained that for SOP power modules, since a single-phase H-bridge converter is used on the AC side, there will be a second-harmonic voltage fluctuation on the DC bus. Therefore, the impact of the dead-time effect needs to be considered when suppressing the dead-time effect.

[0030] Bus voltage second harmonic component u 2nd It can be represented as: (1) Among them, U AB I is the effective value of the fundamental component of the bridge voltage; ω is the angular frequency of the grid voltage; I g1 This is the effective value of the AC side current; φ AB U1 is the phase angle of the AC side current lagging behind the bridge voltage, i.e., the power factor angle; U1 is the average value of the AC-DC side bus voltage, and C1 is the AC-DC side DC bus capacitance.

[0031] In one embodiment provided in this application, generating a first bus voltage command and a second bus voltage command that are not equal includes the following steps B1-B3: B1: Obtain the current phase shift angle and dead time ratio of the DAB converter; B2: Based on the phase shift angle and dead time ratio, determine the minimum bus voltage difference condition required to suppress the polarity reversal of the DAB converter bridge port voltage; B3: Based on the minimum bus voltage difference condition, set the relative magnitudes of the first bus voltage command and the second bus voltage command.

[0032] The process of reading the dead time and switching cycle of the SOP power module is mainly based on the dead time and switching cycle to determine the proportion of the dead time to half a switching cycle, which is used as the dead time proportion.

[0033] Specifically, during voltage polarity reversal, the current flowing through DAB is almost zero, resulting in a reduction in system power. Therefore, to avoid voltage reversal, iL(t) needs to satisfy: (2) Right now (3) Among them, i L(t) represents the DAB inductor current; t0, t1, and t3 all represent time points, with t0 and t1 being the start and end times of the dead time interval, respectively; t3 is the start time of another dead time interval; M represents the proportion of the dead time to half a switching cycle Ths; U1 is the average value of the AC-DC side bus voltage; U2 is the average value of the DC-AC side bus voltage; n is the transformer turns ratio; and D is the proportion of the phase shift angle within half a switching cycle.

[0034] Based on the critical relationship of the two bus voltages determined by the formula (3) above, that is, the minimum bus voltage difference condition, the relative magnitudes of the first bus voltage command and the second bus voltage command are further set.

[0035] In one embodiment provided in this application, obtaining the current phase shift angle of the DAB converter includes the following steps C1-C2: C1: Get the current transmission power of the SOP power module; C2: Set the phase shift angle of the DAB converter according to the transmission power.

[0036] Specifically, when the voltage polarity at the bridge ports reverses, the average transmission power P of the system is as follows: (4) Where U1 and U2 are the average values ​​of the bus voltages on both sides, k is the ratio of the average values ​​of the bus voltages, f is the DAB switching frequency, and L t P1 and P2 are the leakage inductance of the transformer, and are two power components.

[0037] Combining formulas (3) and (4) above, it can be seen that under a certain dead zone, the voltage relationship between the bus voltages U1 and U2 on both sides of the SOP module can be adjusted according to the different phase shift angles, i.e., the different transmission power, so as to eliminate voltage polarity reversal. Therefore, this dead zone effect suppression method mainly calculates the second harmonic fluctuation value of the bus voltage on both sides according to the transmission power of the system, and calculates the difference in bus voltage on both sides required to suppress the voltage drop of the DAB bridge port under the current power. According to the calculation results, the command signal value of the bus voltage on both sides is obtained. The bus voltage control strategy is used to control the bus voltage on both sides to follow the command change, so as to eliminate the voltage drop and polarity reversal of the DAB bridge port. Compared with the traditional scheme, there is no need to add a complex control strategy.

[0038] It should be further explained that when the SOP power module is running, the AC-DC side and DC-AC side are in two different states of rectification and inversion, respectively. The AC power on both sides is equal in magnitude but opposite in direction, and the parameters of the two sides are consistent. Therefore, when the module is running at unit power factor, the second harmonic fluctuation of its respective bus voltage is equal in magnitude but 180 degrees out of phase. So, when the system is running under heavy load, the average value of the bus voltages on both sides is kept equal. When the system is running under light load, the magnitude of the bus voltages on both sides is adjusted to eliminate voltage polarity reversal and voltage drop, as shown in Table 1 below.

[0039] Table 1 Rules for suppressing the dead zone effect

[0040] Reference Figures 4-8 This embodiment provides experimental simulation diagrams based on the dead-zone effect suppression method of this SOP power module. The simulation parameters in Plecs are shown in Table 2 below.

[0041] Table 2 System Parameters

[0042] Simulation results are as follows Figures 4-8 As shown, power transfer from ug1 to ug2 is considered positive, and vice versa is negative.

[0043] Figure 4 When operating under traditional control with positive power and light load, the waveforms of DAB bridge port voltage uab, ucd, and DAB current iL are as follows: the transmission power is 20kW, and the bus voltage commands U1_ref and U2_ref are 750V. At this time, uab exhibits a voltage polarity reversal phenomenon, and iL is always zero at the voltage reversal position.

[0044] Figure 5 The waveform under the proposed control strategy is shown when the power is lightly loaded and the transmission power is 20kW. Under the bus voltage adaptation control strategy, the control bus voltage commands U1_ref and U2_ref are 750V and 715V respectively. At this time, the voltage polarity reversal phenomenon of uab disappears and the zero step of current iL disappears.

[0045] Figure 6 The waveform is under traditional control with negative power and light load operation. The transmission power is negative 20kW, and the bus voltage commands U1_ref and U2_ref are 750V. At this time, ucd shows a voltage polarity reversal phenomenon, and iL is always zero at the voltage reversal position.

[0046] Figure 7The waveform under the proposed control strategy is shown when the power is negative and the load is light. The transmission power is negative 20kW. Under the bus voltage adaptation control strategy, the control bus voltage commands U1_ref and U2_ref are 715V and 750V respectively. At this time, the voltage polarity reversal phenomenon of ucd disappears and the zero step of current iL disappears.

[0047] Figure 8 The waveform under the proposed control strategy is as follows: when the power is negative and the load is full, the transmission power is negative 61kW. Under the bus voltage adaptation control strategy, the control bus voltage commands U1_ref and U2_ref are 750V. There is no voltage polarity reversal phenomenon in uab and ucd. The second harmonic fluctuation in the bus voltage on both sides will cause the current iL spike.

[0048] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0049] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A method for suppressing dead-time effect in SOP power modules, characterized in that: include, Obtain the current transmission power of the SOP power module; Based on the transmission power, a first bus voltage command for controlling the DC bus voltage on the AC-DC side and a second bus voltage command for controlling the DC bus voltage on the DC-AC side are generated. The DC bus voltage on the AC-DC side of the SOP power module is adjusted according to the first bus voltage command, and the DC bus voltage on the DC-AC side of the SOP power module is adjusted according to the second bus voltage command, so as to suppress the polarity reversal of the DAB converter bridge port voltage.

2. The method for suppressing dead-time effect of SOP power modules according to claim 1, characterized in that, The generation of the first bus voltage command and the second bus voltage command based on the transmission power includes: The transmission power is compared with a preset dead-zone effect suppression threshold, which is the transmission power boundary for determining whether the polarity reversal of the DAB converter bridge port voltage needs to be suppressed. If the transmission power is less than the dead-zone effect suppression threshold, the system is determined to be in a light-load mode. If the transmission power is not less than the dead-zone effect suppression threshold, the system is determined to be in a non-light-load mode.

3. The method for suppressing dead-time effect of SOP power module according to claim 2, characterized in that: When the system is in light load mode, it generates a first bus voltage command and a second bus voltage command that are not equal to each other, so that the adjusted DC bus voltage on the AC-DC side is not equal to that on the DC-AC side.

4. The method for suppressing dead-time effect of SOP power module according to claim 2, characterized in that: When the system is in a non-light load mode, a first bus voltage command and a second bus voltage command that are equal to each other are generated so that the adjusted DC bus voltage of the AC-DC side is equal to that of the DC-AC side.

5. The method for suppressing dead-time effect of SOP power modules according to claim 3, characterized in that, The generation of unequal first bus voltage commands and second bus voltage commands includes: Obtain the second harmonic fluctuation component in the DC bus voltage of the SOP power module; The first bus voltage command and the second bus voltage command are compensated based on the second harmonic fluctuation component, so that the actual DC bus voltage on both sides of the SOP power module meets the voltage difference condition required to suppress the polarity reversal of the DAB converter bridge port voltage during the dead time period.

6. The method for suppressing dead-time effect of SOP power module according to claim 3, characterized in that, The generation of unequal first bus voltage commands and second bus voltage commands includes: Obtain the current phase shift angle and dead time ratio of the DAB converter; based on the phase shift angle and dead time ratio, determine the minimum bus voltage difference condition required to suppress the polarity reversal of the DAB converter bridge port voltage; according to the minimum bus voltage difference condition, set the relative magnitudes of the first bus voltage command and the second bus voltage command.

7. The method for suppressing dead-time effect of SOP power module according to claim 6, characterized in that, The process of obtaining the current phase shift angle of the DAB converter includes: Obtain the current transmission power of the SOP power module; The phase shift angle of the DAB converter is set according to the transmission power.

8. The method for suppressing dead-time effect of SOP power module according to claim 6, characterized in that, The process of obtaining the current dead time ratio of the DAB converter includes: Read the dead time and switching cycle of the SOP power module; based on the dead time and switching cycle, determine the proportion of the dead time to half a switching cycle, and use it as the dead time proportion.

9. The method for suppressing dead-time effect of SOP power module according to claim 1, characterized in that: The SOP power module includes an AC-DC converter, a dual active bridge DAB converter, and a DC-AC converter connected in sequence, wherein both the AC-DC converter and the DC-AC converter adopt a single-phase H-bridge structure.

10. The method for suppressing dead-time effect of SOP power module according to any one of claims 5 to 9, characterized in that: The second harmonic fluctuation component is generated by the single-phase H-bridge structure on the AC-DC side or DC-AC side of the SOP power module during the power conversion process.

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