Inverter control method and energy storage equipment

Abstract

The invention discloses an inverter control method and energy storage equipment. The inverter control method comprises the following steps: acquiring the output power of an inverter; determining a modulation mode of the PWM signal according to the output power; the modulation mode of the PWM signal comprises a discontinuous pulse width modulation mode and a space vector pulse width modulation mode; determining a switching frequency parameter of the inverter according to the modulation mode of the PWM signal; the switching frequency parameter comprises at least one of a switching frequency jitter depth, a switching frequency jitter mode and a switching frequency updating speed; a PWM signal is generated based on the switching frequency parameter. The EMC performance of the inverter is comprehensively improved, and the robustness is higher. And meanwhile, the efficiency of the inverter is improved, the dependence on a large-size and high-cost EMI filter is reduced or simplified, the implementation and upgrading are easy, and integration in a product and optimization on site through fixed upgrading are facilitated. And the compactness of the overall structure of the inverter is improved, and the power density of a power system is improved.

Description

Technical Field

[0001] This invention relates to the field of inverters, and more particularly to an inverter control method and an energy storage device. Background Technology

[0002] Traditional methods for improving the electromagnetic compatibility (EMC) of inverters primarily rely on hardware circuitry, such as adding electromagnetic interference (EMI) filters (e.g., common-mode inductors and X / Y capacitors) to the DC and AC sides, and adding snubber circuits to the switching transistors. These methods have inherent drawbacks: 1. High cost: magnetic components and high-voltage film capacitors are bulky and expensive; 2. Large size: contradicting the trend towards inverter miniaturization and high power density; 3. Fixed design: once the hardware is finalized, its EMI suppression effect is fixed and cannot cope with EMI characteristic drift caused by component aging and load changes. Currently, some methods exist to improve EMI through software, but these often have significant side effects. For example, reducing the switching frequency: while reducing the switching noise spectrum, leads to deteriorated output waveform quality (increased harmonics), slower dynamic response, and increased magnetic component size, contradicting the optimization goal. Increasing dead time: While it can prevent bridge arm shoot-through, excessively long dead times can introduce output waveform distortion and reduce inverter efficiency. Therefore, there is an urgent need for a control method that improves EMI without significant side effects to address the aforementioned shortcomings of existing technologies. Summary of the Invention

[0003] This invention provides an inverter control method and an energy storage device, which improves the EMC performance of the inverter and reduces the cost of the inverter.

[0004] In a first aspect, embodiments of the present invention provide an inverter control method, comprising:

[0005] Obtain the output power of the inverter;

[0006] The modulation mode of the PWM signal is determined based on the output power; the PWM signal is used to drive the inverter; the modulation mode of the PWM signal includes discontinuous pulse width modulation mode and space vector pulse width modulation mode.

[0007] The switching frequency parameters of the inverter are determined based on the modulation mode of the PWM signal; the switching frequency parameters include at least one of the following: switching frequency jitter depth, switching frequency jitter mode, and switching frequency update speed.

[0008] The PWM signal is generated based on the switching frequency parameters.

[0009] Optionally, determining the switching frequency parameters of the inverter based on the modulation mode of the PWM signal includes:

[0010] If the modulation mode of the PWM signal is discontinuous pulse width modulation mode, perform one or more of the following: increase the switching frequency jitter depth, decrease the switching frequency update speed, and switch the jitter mode to random jitter mode;

[0011] If the modulation mode of the PWM signal is space vector pulse width modulation mode, perform one or more of the following: reduce the switching frequency jitter depth, increase the switching frequency update speed, and switch the jitter mode to pseudo-random jitter mode.

[0012] Optionally, determining the switching frequency parameters of the inverter based on the modulation mode of the PWM signal includes:

[0013] If the modulation mode of the PWM signal is discontinuous pulse width modulation mode, increase the switching frequency jitter depth, decrease the switching frequency update speed, and switch the switching frequency jitter mode to random jitter mode;

[0014] If the modulation mode of the PWM signal is space vector pulse width modulation mode, reduce the switching frequency jitter depth, increase the switching frequency update speed, and switch the switching frequency jitter mode to pseudo-random jitter mode.

[0015] Optionally, the inverter control method further includes:

[0016] The fundamental frequency of the switching frequency is determined based on the output power.

[0017] After determining the fundamental frequency of the switching frequency based on the output power, the process further includes:

[0018] If the modulation mode of the PWM signal is a discontinuous pulse width modulation mode, reduce the fundamental frequency;

[0019] If the modulation mode of the PWM signal is space vector pulse width modulation mode, increase the fundamental frequency.

[0020] Optionally, the inverter control method further includes:

[0021] Obtain the noise signal of the inverter;

[0022] An EMI feedback signal is generated based on the noise signal;

[0023] The switching frequency parameters are optimized based on the EMI feedback signal.

[0024] Optionally, generating an EMI feedback signal based on the noise signal includes:

[0025] An initial EMI feedback signal is generated based on the noise signal;

[0026] The initial EMI feedback signal is optimized based on the modulation mode of the PWM signal and the switching frequency parameters to form the EMI feedback signal.

[0027] Optionally, before generating the PWM signal based on the switching frequency parameters, the method further includes:

[0028] If the switching frequency is greater than the fundamental frequency, reduce the rise time or fall time of the PWM signal;

[0029] If the switching frequency is less than the fundamental frequency, increase the rise time or fall time of the PWM signal.

[0030] Optionally, after generating the EMI feedback signal based on the noise signal, the method further includes:

[0031] When the EMI feedback signal is greater than the preset EMI value, the modulation mode of the PWM signal is set to the discontinuous pulse width modulation mode;

[0032] The switching frequency jitter depth is set to the maximum preset value within the jitter preset range;

[0033] Set the rise time or fall time of the PWM signal to the maximum preset time within the preset time range.

[0034] Optionally, determining the modulation mode of the PWM signal based on the output power includes:

[0035] Obtain multiple output powers within a preset time period;

[0036] The rate of change of the output power is determined based on multiple output powers;

[0037] If the output power at the current moment is greater than or equal to a first preset value, and / or the rate of change of the output power is greater than or equal to a second preset value, the modulation mode of the PWM signal is determined to be the space vector pulse width modulation mode.

[0038] If the output power at the current moment is less than or equal to a third preset value, and / or the rate of decrease of the output power is greater than or equal to a fourth preset value, the modulation mode of the PWM signal is determined to be a discontinuous pulse width modulation mode; wherein the third preset value is less than the first preset value.

[0039] Secondly, embodiments of the present invention provide an energy storage device, including an inverter and a controller, wherein the controller is used to control the inverter to implement the inverter control method described in the first aspect.

[0040] The technical solution of this invention determines the modulation mode of the PWM signal based on the inverter's output power, ensuring that the modulation mode matches the inverter's load state. This reduces the number of switching operations when the inverter is under light load, directly lowering switching losses and EMI noise at the source. Conversely, it increases the number of switching operations when the inverter is under heavy load, ensuring the quality of the inverter's output waveform. Through software optimization, electromagnetic interference generated during the switching process of the inverter's transistors can be dynamically and adaptively suppressed, balancing waveform quality and switching losses to achieve optimal coordination between efficiency and EMI performance. Furthermore, after determining the PWM signal modulation mode, the inverter's switching frequency parameters can be determined accordingly. Under the PWM signal modulation mode, the switching frequency of the provided PWM signal varies within a small range near the fundamental frequency according to a set switching frequency jitter pattern. This disperses interference energy concentrated at the fundamental frequency and its harmonics across a frequency band within the switching frequency jitter depth range, significantly reducing the quasi-peak interference level at any specific frequency point, comprehensively improving the inverter's EMC performance, and enhancing its robustness. Simultaneously, it allows the switching frequency update speed to match the current PWM signal modulation mode, ensuring output waveform quality requirements, improving EMI measurement accuracy, and enhancing the stability of the inverter control system. While effectively suppressing EMI, it reduces the impact on THD of the output waveform quality and inverter efficiency, thus improving inverter efficiency. It also reduces or simplifies reliance on bulky, high-cost EMI filters, achieving "software-driven hardware," facilitating implementation and upgrades without modifying the hardware structure. This allows for easy integration into the product and optimization through fixed upgrades in the field. Furthermore, it improves the overall compactness of the inverter structure and increases the power density of the power system. Attached Figure Description

[0041] Figure 1 A flowchart illustrating an inverter control method provided in an embodiment of the present invention;

[0042] Figure 2 This is a comparative schematic diagram showing the operation of the switching transistor under different PWM signal modulation modes, provided as an embodiment of the present invention.

[0043] Figure 3 A schematic diagram of interference level curves for an inverter using different switching frequency settings, provided as an embodiment of the present invention;

[0044] Figure 4A flowchart illustrating another inverter control method provided in an embodiment of the present invention;

[0045] Figure 5 A flowchart illustrating another inverter control method provided in an embodiment of the present invention;

[0046] Figure 6 An interactive schematic diagram of a controller provided in an embodiment of the present invention;

[0047] Figure 7 A flowchart illustrating another inverter control method provided in an embodiment of the present invention;

[0048] Figure 8 A schematic diagram of voltage variation curves of an inverter using different shutdown methods is provided for an embodiment of the present invention.

[0049] Figure 9 A flowchart illustrating another inverter control method provided in an embodiment of the present invention;

[0050] Figure 10 A flowchart illustrating another inverter control method provided in an embodiment of the present invention;

[0051] Figure 11 A schematic diagram illustrating the workflow of a modulation switching module provided in an embodiment of the present invention;

[0052] Figure 12 A schematic diagram illustrating the workflow of a spectrum modulation module provided in an embodiment of the present invention;

[0053] Figure 13 This is a schematic diagram of the structure of an energy storage device provided in an embodiment of the present invention. Detailed Implementation

[0054] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0055] This invention provides an inverter control method for controlling the operating state of an inverter. The inverter can be applied to photovoltaic devices, energy storage devices, and uninterruptible power supplies (UPS), etc. The inverter includes a bridge circuit, such as a half-bridge or full-bridge, and can also be a multi-phase bridge circuit. The bridge circuit includes switching transistors, and the inverter control method controls the conduction state of each switching transistor, thereby controlling the operating state of the inverter. The inverter control method provided in this invention can be executed by a controller. Figure 1This is a flowchart illustrating an inverter control method provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the inverter control method includes:

[0056] S110, Obtain the output power of the inverter.

[0057] Specifically, the inverter controller may include an acquisition module for acquiring the inverter's output power. The output power can be determined by the inverter's output voltage and output current. When acquiring the inverter's output power, the acquisition module can directly acquire the inverter's output power; for example, the acquisition module may include a power meter. The acquisition module can also acquire the inverter's output voltage and output current separately to determine the inverter's output power. For example, the acquisition module may include a voltage transformer and a current transformer. When the inverter's output power is greater than or equal to a preset power value, the inverter can be determined to be in heavy-load mode. When the inverter's output power is less than the preset power value, the inverter can be determined to be in light-load mode. The preset power value can be determined based on the inverter's load-carrying capacity.

[0058] S120. Determine the modulation mode of the PWM signal based on the output power; the PWM signal is used to drive the inverter; the modulation modes of the PWM signal include discontinuous pulse width modulation mode and space vector pulse width modulation mode.

[0059] Specifically, when the controller controls the operation of the switching transistors in the inverter, it can provide pulse width modulation (PWM) signals to the transistors. The controller also includes a modulation switching module to dynamically switch the modulation mode of the PWM signal based on the output power. When the inverter's output power is less than a preset power value, it can be determined that the inverter is in light-load mode, and the modulation mode of the PWM signal can be determined to be discontinuous pulse width modulation (DPWM). At this time, the modulation switching module can switch the modulation mode of the PWM signal to DPWM mode through an adaptive modulation strategy. By continuously clamping the upper or lower switching transistor of a certain phase arm in the inverter during certain carrier cycles, the switching frequency of the transistors can be reduced by up to 33%, thereby directly reducing the inverter's switching losses and EMI noise at the source. The switching frequency refers to the number of times the transistor switches within the cycle corresponding to the fundamental frequency.

[0060] When the inverter's output power is greater than or equal to a preset power value, it can be determined that the inverter is in heavy-load mode. Therefore, the modulation mode of the PWM signal can be determined to be Space Vector Pulse Width Modulation (SVPWM). At this time, the modulation switching module can switch the PWM signal module to SVPWM mode through an adaptive modulation strategy, ensuring the quality of the inverter's output waveform. Thus, the modulation mode of the PWM signal can be automatically switched according to the inverter's load state without increasing the inverter's cost, reducing EMI noise while ensuring the quality of the inverter's output waveform.

[0061] For example, Figure 2 This is a comparative diagram showing the operation of the switching transistors under different PWM signal modulation modes, as provided in an embodiment of the present invention. The horizontal axis represents electrical angles, and the vertical axis represents the number of switching actions. Curve 11 represents the number of switching actions of the upper arm switch of the inverter in the entire cycle under SVPWM mode; curve 12 represents the number of switching actions of the lower arm switch of the inverter in the entire cycle under SVPWM mode; curve 13 represents the number of switching actions of the upper arm switch of the inverter in the entire cycle under DPWM mode; and curve 14 represents the number of switching actions of the lower arm switch of the inverter in the entire cycle under DPWM mode. Figure 2 As shown, in SVPWM mode, the switches of the upper and lower bridge arms maintain high-frequency switching, and the switching actions are relatively evenly distributed throughout the cycle. Each switch performs approximately 12-15 switching actions in one fundamental cycle. In DPWM mode, the upper bridge arm switch is fully clamped in the 120°-240° range (0 switching actions), and the lower bridge arm switch is clamped in the 0°-120° and 240°-360° ranges. The switching actions are concentrated in specific ranges, with no switching in other ranges. Each switch performs approximately 4-6 switching actions in one fundamental cycle.

[0062] It should be noted that in some embodiments, the modulation mode of the PWM signal also includes a sinusoidal pulse width modulation (SPWM) mode as a backup mode for the DPWM and SVPWM modes. When an inverter malfunctions, causing abnormalities in the DPWM and SVPWM modes, the inverter can be controlled via the SPWM mode to ensure its normal operation.

[0063] S130. Determine the switching frequency parameters of the inverter based on the modulation mode of the PWM signal; the switching frequency parameters include at least one of the following: switching frequency jitter depth, switching frequency jitter mode, and switching frequency update speed.

[0064] Specifically, the switching frequency is the number of times the switching transistor switches within the period of the fundamental frequency. The switching frequency jitter depth is the fluctuation range of the switching frequency. For example, the switching frequency jitter depth can be ±5%, in which case the fluctuation range of the switching frequency is ±5% of the fundamental frequency.

[0065] The switching frequency jittering method refers to the variation pattern of the switching frequency within the jittering depth range near the fundamental frequency. For example, the switching frequency jittering method can include random jittering or jittering according to a specific pattern. Random jittering can be a jittering method where the switching frequency changes in a random sequence within the fluctuation range of the fundamental frequency (i.e., within the fundamental frequency jittering depth), to ensure the control stability of the inverter. Jittering according to a specific pattern can be a jittering method where the switching frequency changes in a specific pattern within the fluctuation range. For example, a jittering method according to a specific pattern can include a jittering method where the switching frequency changes according to a pseudo-random sequence, triangular wave, or sine wave pattern within the fluctuation range of the fundamental frequency, to achieve electromagnetic interference frequency diffusion while ensuring output waveform quality. In this way, the switching frequency of the PWM signal varies in a small range near the fundamental frequency according to the set switching frequency jitter mode. This allows the interference energy concentrated at the fundamental frequency and its harmonics to be "dispersed" to the frequency band within the switching frequency jitter depth range, thereby significantly reducing the quasi-peak interference level at any specific frequency point, reducing the inverter's EMI, and making the inverter easier to pass EMC conducted interference tests.

[0066] The switching frequency update rate is the speed at which the switching frequency is updated, and it can be limited by the number of switching cycles. The switching cycle and the switching frequency are reciprocals of each other; that is, the product of the switching cycle and the switching frequency is 1 second. For example, the switching frequency update rate can be 5 switching cycles, meaning the switching frequency is updated after 5 switching cycles. The switching frequency jitter period is positively correlated with the switching frequency update rate. The switching frequency jitter period is the time from the update time to the next update time, used to characterize the time during which the switching frequency jitters at the current jitter depth and jitter pattern.

[0067] After determining the modulation mode of the PWM signal, the switching frequency parameters of the inverter can be determined based on the modulation mode, ensuring that the switching frequency parameters provided by the PWM signal modulation mode match the output power of the inverter. This allows for the distribution of interference energy concentrated at the fundamental frequency and its harmonics across a wider frequency band, while meeting the quality requirements of the output waveform under different load conditions. This ensures effective electromagnetic interference frequency diffusion, reduces quasi-peak interference levels, and improves the accuracy of EMI measurement and the stability of the inverter control system.

[0068] For example, Figure 3 This is a schematic diagram illustrating the interference level curves of an inverter using different switching frequency settings, provided as an embodiment of the present invention. The horizontal axis represents frequency, and the vertical axis represents interference level. Curve 1 shows the amplitude of the interference level when the PWM signal uses a traditional fixed switching frequency, and curve 2 shows the amplitude of the interference level when the PWM signal uses the switching frequency parameters provided in this embodiment. Figure 3 As shown, when the PWM signal uses the switching frequency parameters provided in this embodiment, the interference level decreases significantly.

[0069] S140 generates a PWM signal based on the switching frequency parameter.

[0070] Specifically, after determining the switching frequency parameters, the final PWM signal can be determined based on the modulation mode of the PWM signal and the switching frequency parameters. The PWM signal is then transmitted to the driver chip, which amplifies it into a high-power drive signal, optimizing the PWM signal for driving the switching transistors in the inverter. This allows for dynamic and adaptive suppression of electromagnetic interference generated during the switching process of the inverter transistors through software optimization, comprehensively improving the inverter's EMC performance and enhancing its robustness. While effectively suppressing EMI, it reduces the impact on total harmonic distortion (THD) of the output waveform quality and inverter efficiency, thus improving inverter efficiency. It also reduces or simplifies the reliance on bulky, high-cost EMI filters, achieving "software-driven hardware," facilitating implementation and upgrades without modifying the hardware structure. This makes it easy to integrate into products and optimize through fixed upgrades in the field. Furthermore, it improves the overall compactness of the inverter structure and increases the power density of the power system.

[0071] The technical solution of this embodiment determines the modulation mode of the PWM signal based on the inverter's output power, ensuring that the modulation mode matches the inverter's load state. This reduces the number of switching operations when the inverter is under light load, directly reducing switching losses and EMI noise at the source. When the inverter is under heavy load, the number of switching operations increases to maintain the quality of the inverter's output waveform. Thus, through software optimization, electromagnetic interference generated during the switching process of the inverter's switching transistors can be dynamically and adaptively suppressed, balancing waveform quality and switching losses to achieve optimal coordination between efficiency and EMI performance. After determining the modulation mode of the PWM signal, the inverter's switching frequency parameters can be adjusted according to the modulation mode. Under the PWM signal modulation mode, the switching frequency of the provided PWM signal varies within a small range near the fundamental frequency according to a set switching frequency jitter pattern. Interference energy concentrated at the fundamental frequency and its harmonics is "dispersed" across the frequency band within the switching frequency jitter depth range, significantly reducing the quasi-peak interference level at any specific frequency point, further reducing EMI in specific frequency bands, comprehensively improving the inverter's EMC performance, and enhancing its robustness. Simultaneously, it allows the switching frequency update speed to match the current PWM signal modulation mode, ensuring output waveform quality requirements, improving EMI measurement accuracy, and enhancing the stability of the inverter control system. While effectively suppressing EMI, it reduces the impact on THD of the output waveform quality and inverter efficiency, thus contributing to improved inverter efficiency. It also reduces or simplifies reliance on bulky, high-cost EMI filters, achieving "software-driven hardware," facilitating implementation and upgrades without modifying the hardware structure. This allows for easy integration into the product and optimization through fixed upgrades in the field. It improves the overall compactness of the inverter structure and increases the power density of the power system.

[0072] In some embodiments, determining the inverter's switching frequency parameters based on the modulation mode of the PWM signal includes:

[0073] If the modulation mode of the PWM signal is discontinuous pulse width modulation mode, execute one or more of the following: increase the switching frequency jitter depth, decrease the switching frequency update speed, and switch the jitter mode to random jitter mode.

[0074] Specifically, when the inverter is in light-load mode, the PWM signal modulation mode is DPWM mode, which has relatively low requirements for the quality of the output waveform. At this time, the number of switching cycles is relatively small, and the switching frequency jitter depth can be increased, allowing for a wider jitter range. This disperses interference energy concentrated at the fundamental frequency and its harmonics as much as possible across a wider frequency band, further reducing quasi-peak interference levels and improving the inverter's EMC performance. And / or, it can reduce the switching frequency update speed, resulting in a longer residence time at each frequency point. This ensures that EMI testing equipment (such as a spectrum analyzer) can effectively record the energy diffusion, improving the accuracy of EMI measurements. Simultaneously, it ensures that the inverter's control loop has sufficient time to complete the adjustment of the current switching frequency, maintaining the stability of the inverter control system. When the switching frequency changes, the change is relatively smooth, avoiding drastic and continuous phase changes in the PWM signal itself, thus preventing the introduction of new EMI noise during EMI noise elimination. In DPWM mode, increasing the switching frequency jitter depth and decreasing the switching frequency update speed can fully utilize the low switching losses of DPWM mode and avoid introducing additional control complexity due to frequent frequency switching. At this time, DPWM mode reduces the number of switching operations, reducing EMI at the source. The switching frequency jitter depth disperses the remaining EMI noise spectrum, further reducing quasi-peak interference levels. And / or, the jitter mode can be switched to random jitter mode, which can further improve the control stability of the inverter.

[0075] If the modulation mode of the PWM signal is space vector pulse width modulation mode, perform one or more of the following: reduce the switching frequency jitter depth, increase the switching frequency update speed, and switch the jitter mode to pseudo-random jitter mode.

[0076] Specifically, when the inverter is in heavy-load mode, the PWM signal modulation mode is SVPWM mode, and the quality requirements for the output waveform are very high. At this time, the number of switching cycles is relatively large. Therefore, the switching frequency jitter depth can be reduced, and / or the switching frequency update speed can be increased, and / or the jitter mode can be switched to a pseudo-random jitter mode with good correlation characteristics. This aims to achieve optimal electromagnetic interference spectrum diffusion while ensuring the quality of the output waveform, and to ensure the strict reproducibility of battery compatibility testing.

[0077] In some embodiments, determining the switching frequency parameters of the inverter based on the modulation mode of the PWM signal includes:

[0078] If the modulation mode of the PWM signal is discontinuous pulse width modulation mode, increase the switching frequency jitter depth, decrease the switching frequency update speed, and switch the switching frequency jitter mode to random jitter mode.

[0079] Specifically, when the modulation mode of the PWM signal is DPWM mode, it is possible to simultaneously increase the switching frequency jitter depth, reduce the switching frequency update speed, and switch the switching frequency jitter mode to random jitter mode. While meeting the quality requirements of the output wave, it is possible to further reduce the quasi-peak interference level, thereby improving the measurement accuracy of EMI and the stability of the inverter control system, and improving the EMC performance of the inverter.

[0080] If the modulation mode of the PWM signal is space vector pulse width modulation mode, reduce the switching frequency jitter depth, increase the switching frequency update speed, and switch the switching frequency jitter mode to pseudo-random jitter mode.

[0081] Specifically, when the modulation mode of the PWM signal is SVPWM mode, it can simultaneously reduce the switching frequency jitter depth, increase the switching frequency update speed, and switch the switching frequency jitter mode to pseudo-random jitter mode to ensure the quality requirements of the output waveform. At the same time, it can maximize the electromagnetic interference frequency diffusion effect and improve the EMC performance of the inverter.

[0082] Figure 4 A flowchart illustrating another inverter control method provided in an embodiment of the present invention is shown below. Figure 4 As shown, the inverter control method includes:

[0083] S210, Obtain the output power of the inverter.

[0084] S220. Determine the modulation mode of the PWM signal and the fundamental frequency of the switching frequency based on the output power.

[0085] Specifically, the fundamental frequency is the center value of the switching frequency jitter range. For example, the fundamental frequency can be 50Hz. Different output power values ​​of the inverter can characterize the inverter's load state. For example, when the inverter's output power is greater than or equal to a preset power value, the inverter is in heavy load mode, and the fundamental frequency can be set relatively high. When the inverter's output power is less than the preset power value, the inverter is in light load mode, and the fundamental frequency can be set relatively low. For example, when the inverter is in light load mode, the PWM signal modulation mode is DPWM mode, and the fundamental frequency can be 47Hz. When the inverter is in heavy load mode, the PWM signal modulation mode is SVPWM mode, and the fundamental frequency can be 49Hz or 50Hz.

[0086] S230. When the modulation mode of the PWM signal is discontinuous pulse width modulation mode, perform one or more of the following actions: increase the switching frequency jitter depth, decrease the switching frequency update speed, and switch the jitter mode to random jitter mode, thereby reducing the fundamental frequency.

[0087] Specifically, when the modulation mode of the PWM signal is DPWM mode, the fundamental frequency can be reduced, switching losses can be reduced, and EMC test frequency points can be avoided, making it easier to meet EMC test requirements. It also avoids sensitive radio frequency bands that may exist in other systems.

[0088] S240. When the modulation mode of the PWM signal is space vector pulse width modulation mode, perform one or more of the following: reduce the switching frequency jitter depth, increase the switching frequency update speed, and switch the jitter mode to pseudo-random jitter mode, and increase the fundamental frequency.

[0089] Specifically, when the modulation mode of the PWM signal is SVPWM mode, the fundamental frequency can be increased, which can further improve the quality of the output waveform.

[0090] S250 generates PWM signals based on switching frequency parameters.

[0091] Figure 5 A flowchart illustrating another inverter control method provided in an embodiment of the present invention is shown below. Figure 5 As shown, the inverter control method includes:

[0092] S310: Obtain the output power and noise signal of the inverter.

[0093] Specifically, the noise signal is used to characterize the EMI level of the current inverter. For example, the noise signal can be a high-frequency common-mode current signal or an interference signal, and the acquisition module can include a current sensor (such as a Rogowski coil) to sample and acquire the noise signal.

[0094] S320. Determine the modulation mode of the PWM signal based on the output power; the PWM signal is used to drive the inverter; the modulation modes of the PWM signal include discontinuous pulse width modulation mode and space vector pulse width modulation mode.

[0095] S330. Determine the switching frequency parameters of the inverter based on the modulation mode of the PWM signal; the switching frequency parameters include at least one of the following: switching frequency jitter depth, switching frequency jitter mode, and switching frequency update speed.

[0096] S340: Generates an EMI feedback signal based on the noise signal.

[0097] Specifically, the controller also includes a closed-loop EMI suppression module, which can generate an EMI feedback signal through an adaptive algorithm (such as the LMS algorithm) to characterize the noise signal.

[0098] S350 optimizes switching frequency parameters based on EMI feedback signals.

[0099] Specifically, after determining the EMI feedback signal, the switching frequency parameters are fine-tuned based on the EMI feedback signal to minimize the noise signal of the feedback loop and achieve dynamic and adaptive optimal EMI control.

[0100] It should be noted that when the EMI feedback signal includes interference in a specific frequency band, the jitter mode can be dynamically switched to a random sequence with different statistical characteristics (such as the longest period sequence), which can achieve full-dimensional, adaptive optimal EMI control from the noise source, propagation path to the spectrum shape.

[0101] S360 generates PWM signals based on switching frequency parameters.

[0102] In some embodiments, generating an EMI feedback signal based on a noise signal includes:

[0103] An initial EMI feedback signal is generated based on the noise signal.

[0104] Specifically, after acquiring the noise signal, the noise signal can be processed to form an initial EMI feedback signal.

[0105] The initial EMI feedback signal is optimized based on the modulation mode and switching frequency parameters of the PWM signal to form an EMI feedback signal.

[0106] Specifically, the closed-loop EMI suppression module can also receive the modulation mode of the PWM signal provided by the modulation switching module and the switching frequency parameters provided by the spectrum modulation module. After the closed-loop EMI suppression module generates the initial EMI feedback signal based on the noise signal, it can optimize the initial EMI feedback signal according to the modulation mode and switching frequency parameters of the PWM signal, thus forming a better EMI feedback signal that matches the current load state and EMI state of the inverter. This allows for a better balance between EMI suppression and output waveform quality, improving the overall performance of the inverter.

[0107] Specifically, Figure 6 This is a schematic diagram illustrating the interaction of a controller according to an embodiment of the present invention. Figure 6As shown, after the acquisition module acquires the output power and noise signals, it transmits the output power to the modulation switching module. The modulation switching module determines the modulation mode of the PWM signal based on the output power and sends the modulation mode to the spectrum modulation module and the closed-loop EMI suppression module. The spectrum modulation module determines the inverter's switching frequency parameters based on the PWM signal's modulation mode and sends the switching frequency parameters to the closed-loop EMI suppression module. The closed-loop EMI suppression module generates an EMI feedback signal based on the noise signal, the PWM signal's modulation mode, and the switching frequency parameters, and sends it to the spectrum modulation module. The spectrum modulation module dynamically optimizes the switching frequency parameters based on the EMI feedback signal and sends the optimized switching frequency parameters to the driver chip to drive the inverter.

[0108] Figure 7 A flowchart illustrating another inverter control method provided in an embodiment of the present invention is shown below. Figure 7 As shown, the inverter control method includes:

[0109] S410: Obtain the output power of the inverter.

[0110] S420. Determine the modulation mode of the PWM signal based on the output power; the PWM signal is used to drive the inverter; the modulation modes of the PWM signal include discontinuous pulse width modulation mode and space vector pulse width modulation mode.

[0111] S430. Determine the switching frequency parameters of the inverter based on the modulation mode of the PWM signal; the switching frequency parameters include at least one of the following: switching frequency jitter depth, switching frequency jitter mode, and switching frequency update speed.

[0112] S440. Adjust the driving parameters of the PWM signal according to the switching frequency parameters; the driving parameters include the rise time and / or fall time of the PWM signal.

[0113] Specifically, the controller may also include an active drive module for adjusting the drive parameters of the PWM signal. After determining the switching frequency parameters, the rise time and / or fall time of the PWM signal can be adjusted according to the switching frequency parameters to adjust the voltage slope of the PWM signal, thereby adjusting the turn-off and turn-on speeds of the switching transistor. This allows the switching transistor to use a relatively gentle turn-off speed to reduce voltage spikes and voltage change rate when turned off. Conversely, a relatively steep turn-on speed is used when the switching transistor is turned on to ensure conduction efficiency. This "soft turn-off, hard turn-on" strategy can generate a drive waveform with an optimized switching slope, directly reducing the voltage change rate and voltage spikes during the switching process, effectively suppressing EMI. For example, by setting the switching transistor to "soft turn off," the voltage change rate during the switching process can be reduced from the traditional greater than 100V / ns to approximately 25V / ns. The corresponding high-frequency EMI components (30-100MHz) can be reduced by 10-15dB, while also reducing voltage overshoot and ringing during the switching process.

[0114] For example, Figure 8 This diagram illustrates the voltage variation curves of an inverter using different turn-off methods, as provided in an embodiment of the present invention. The horizontal axis represents time, and the vertical axis represents voltage. Curve 3 represents the gate drive voltage of the switching transistor, curve 4 represents the voltage variation curve when the inverter uses conventional hard turn-off, and curve 5 represents the voltage variation curve when the inverter uses the soft turn-off method provided in this embodiment of the invention. Figure 8 As shown, at t=3μs, the gate drive voltage drops instantaneously from 15V to 0V, which is the turn-off command for the switching transistor. Curve 4 shows that after the turn-off command is issued, the voltage across the switching transistor rises almost vertically, jumping instantaneously from 50V to 500V, generating extremely high du / dt (voltage change rate) and significant electromagnetic interference. Curve 5 shows that after the turn-off command is issued, the voltage across the switching transistor rises slowly and linearly, taking approximately 4μs to rise from 50V to 500V, significantly reducing the du / dt (voltage change rate).

[0115] S450 generates PWM signals based on switching frequency parameters.

[0116] In some embodiments, adjusting the drive parameters of the PWM signal according to the switching frequency parameter includes:

[0117] If the switching frequency is greater than the fundamental frequency, reduce the rise time or fall time of the PWM signal.

[0118] Specifically, when the switching frequency is higher than the fundamental frequency, the switching frequency is high. In this case, the rise time or fall time of the PWM signal can be reduced to shorten the soft turn-off time of the switching transistor and avoid efficiency loss. For example, when the switching transistor is turned off at a high level, the rise time of the PWM signal can be reduced. When the switching transistor is turned off at a low level, the fall time of the PWM signal can be reduced.

[0119] If the switching frequency is less than the fundamental frequency, increase the rise time or fall time of the PWM signal.

[0120] Specifically, when the switching frequency is lower than the fundamental frequency, the switching frequency is considered low. In this case, the rise time or fall time of the PWM signal can be increased to enhance EMI suppression. For example, when the switch is off at a high level, the rise time of the PWM signal can be increased. When the switch is off at a low level, the fall time of the PWM signal can be increased.

[0121] In some embodiments, adjusting the drive parameters of the PWM signal according to the switching frequency parameter includes:

[0122] Adjust the gate drive resistor of the switching transistor in the inverter according to the switching frequency parameter.

[0123] Specifically, the gate drive resistor of the switching transistor can adjust the rate of change of the gate voltage, thereby adjusting the rise or fall time of the PWM signal, and thus regulating the turn-on and turn-off speeds of the transistor. For example, when the transistor is turned off, the gate drive resistor can be increased to give the transistor a relatively gentle turn-off speed, reducing voltage spikes and the rate of voltage change. When the transistor is turned on, the gate drive circuit can be reduced to give the transistor a relatively steep turn-on speed, ensuring the transistor's conduction efficiency.

[0124] It should be noted that in other embodiments, a multi-stage turn-off drive circuit can also be used to achieve the "soft turn-off" process of the switching transistor, which will not be elaborated here.

[0125] Figure 9 A flowchart illustrating another inverter control method provided in an embodiment of the present invention is shown below. Figure 9 As shown, the inverter control method includes:

[0126] S510: Obtain the inverter's output power and noise signal.

[0127] S520. Determine the modulation mode of the PWM signal based on the output power; the PWM signal is used to drive the inverter; the modulation modes of the PWM signal include discontinuous pulse width modulation mode and space vector pulse width modulation mode.

[0128] S530. Determine the switching frequency parameters of the inverter based on the modulation mode of the PWM signal; the switching frequency parameters include at least one of the following: switching frequency jitter depth, switching frequency jitter mode, and switching frequency update speed.

[0129] S540 generates an EMI feedback signal based on the noise signal.

[0130] S550: When the EMI feedback signal is greater than the preset EMI value, the modulation mode of the PWM signal is set to discontinuous pulse width modulation mode.

[0131] Specifically, the preset EMI value can be determined based on the EMI values ​​that can be tolerated during EMC testing of the inverter. When the EMI feedback signal is greater than the preset EMI value, it indicates that the inverter's current EMI value exceeds the standard, meaning that the inverter's current EMI value cannot pass the EMC test. At this time, the closed-loop EMI suppression module sends a command to the modulation switching module, causing the modulation switching module to forcibly switch the modulation mode of the PWM signal to DPWM mode, which can reduce the switching losses of the switching transistors and directly reduce the inverter's switching losses and EMI noise from the source.

[0132] S560, Set the switching frequency jitter depth to the maximum preset value within the jitter preset range.

[0133] Specifically, when the inverter's current EMI value fails the EMC test, the closed-loop EMI suppression module simultaneously sends a command to the spectrum modulation module. This command forces the spectrum modulation module to set the switching frequency jitter depth in the switching frequency parameters to the maximum preset value within the jitter preset range. This allows the switching frequency to have the maximum jitter range, dispersing interference energy concentrated at the fundamental frequency and its harmonics as much as possible across a wider frequency band, further reducing quasi-peak interference levels and improving the inverter's EMC performance. For example, the preset jitter range for the switching frequency jitter depth can include ±7.5%, ±5%, and ±3.5%. When the inverter's current EMI value fails the EMC test, and the closed-loop EMI suppression module sends a command to the spectrum modulation module, the spectrum modulation module directly switches the switching frequency jitter depth to ±7.5% according to the command.

[0134] S570: Set the rise time or fall time of the PWM signal to the maximum preset time within the preset time range.

[0135] Specifically, when the inverter's current EMI value fails the EMC test, the closed-loop EMI suppression module simultaneously sends a command to the active drive module. This causes the active drive module to set the rise time or fall time of the PWM signal to the maximum preset time within a preset range, initiating the strongest "soft shutdown" to minimize the voltage change rate and voltage spikes during the switching process, effectively suppressing EMI. Thus, by maximizing the reduction of switching frequency, dispersing interference energy, and minimizing the voltage change rate and voltage spikes during the switching process, the inverter's EMI suppression effect is improved in multiple ways, maximizing its EMI suppression performance, rapidly reducing the EMI value, and enabling the inverter to pass the EMC test.

[0136] S580 generates PWM signals based on switching frequency parameters.

[0137] Figure 10 A flowchart illustrating another inverter control method provided in an embodiment of the present invention is shown below. Figure 10 As shown, the inverter control method includes:

[0138] S610: Obtain multiple output powers within a preset time period.

[0139] Specifically, the preset duration can be set according to the variation pattern of output power. For example, if the output power rapidly increases between 8:30 AM and 10:00 AM on a certain day, the preset duration could be one and a half hours. The time intervals between multiple output power levels can be equal to calculate the rate of change of output power. For example, the time interval between multiple output power levels could be 10 minutes.

[0140] S620: Determine the rate of change of output power based on multiple output powers.

[0141] Specifically, after acquiring multiple output powers, the rate of change of the current output power can be determined based on the ratio of the difference between two adjacent output powers to the previous output power.

[0142] S630. If the output power at the current moment is greater than or equal to the first preset value, and / or the rate of change of the output power is greater than or equal to the second preset value, determine that the modulation mode of the PWM signal is space vector pulse width modulation mode.

[0143] Specifically, the first preset value can be determined based on the inverter's operating state. If the current output power is greater than or equal to the first preset value, the inverter can be determined to be in heavy load mode, and the modulation mode of the PWM signal can be determined to be Space Vector Pulse Width Modulation (SVPWM). For example, the first preset value can be 2.5kW. And / or, if the rate of increase of the output power is greater than or equal to the second preset value, it can be determined that the inverter's load has increased significantly, and the modulation mode of the PWM signal can be determined to be SVPWM. For example, the inverter's output power jumps from 1.2kW to 3.0kW within 10 minutes.

[0144] S640. If the output power at the current moment is less than or equal to the third preset value, and / or the rate of change of the output power is greater than or equal to the fourth preset value, determine that the modulation mode of the PWM signal is discontinuous pulse width modulation mode; wherein, the third preset value is less than the first preset value.

[0145] Specifically, the third preset value can be determined based on the inverter's operating state. If the current output power is less than or equal to the third preset value, the inverter is in light-load mode, and the modulation mode of the PWM signal is determined to be discontinuous pulse width modulation (DPWM). For example, the third preset value can be 1.5kW. And / or if the rate of change of output power is greater than or equal to the fourth preset value, the inverter's load is determined to have decreased significantly, and the modulation mode of the PWM signal is determined to be discontinuous pulse width modulation (DPWM). For example, the inverter's output power decreases from 7.5kW to 1.8kW within 2 minutes.

[0146] S650. Determine the switching frequency parameters of the inverter based on the modulation mode of the PWM signal; the switching frequency parameters include at least one of the following: switching frequency jitter depth, switching frequency jitter mode, and switching frequency update speed.

[0147] S660 generates PWM signals based on switching frequency parameters.

[0148] The following example illustrates the inverter control method. For instance, in a photovoltaic (PV) power generation system, sunlight is weak in the morning, resulting in lower power output. A customer watching television at home experiences poor signal quality due to inverter EMC (Electromagnetic Compatibility) issues. The acquisition module detects low inverter output power. Based on this, the modulation switching module determines the PWM signal modulation mode to DPWM (Digital-to-PWM) to reduce EMI and sets the fundamental frequency to 47kHz, avoiding the television signal's frequency band. Simultaneously, the spectrum modulation module sets the switching frequency jitter depth to ±7.5% according to the DPWM mode and sets the switching frequency jitter method to a slow random sequence, with a switching frequency update speed of 5 switching cycles, thus eliminating EMC effects.

[0149] In another example, the photovoltaic power generation system is an 8kW single-phase photovoltaic inverter, supplying power to a detached house, with EMC requirements of Class B, and the season is a typical weekday in June, with sunny weather but brief cloud cover. The coordinated process of the inverter control method in a specific time series:

[0150] 1. Low-Power Morning Operation: At dawn, with the sun just rising and irradiance at 300W / m², the inverter output power is 0.8-1.2kW. Neighboring photovoltaic systems are watching the morning news (sensitive to EMI). At this time, the acquisition module continuously monitors the output power below the 1.5kW threshold, the ambient temperature is 18°C, and heat dissipation is good. The modulation switching module determines the PWM signal modulation mode to DPWM. The spectrum modulation module sets the fundamental frequency to 47kHz according to the DPWM mode, avoiding the TV signal frequency band. The switching frequency jitter depth is ±7.5% (within a 37.5kHz range), and the switching frequency jitter method is set to a slow random sequence, with a switching frequency update speed of 5 switching cycles. At this time, the impact on neighbors disappears, the inverter efficiency is 96.2%, and the chassis temperature remains at 42°C.

[0151] 2. Rapid Power Rise Period: Solar irradiance rises to 600W / m², inverter output power is 2.8-3.2kW, and household appliances start (e.g., washing machines and air conditioners). At this time, the acquisition module detects that the output power jumps from 1.2kW to 3.0kW within 10 minutes, while load harmonics in the noise signal increase (washing machine motor starts). The modulation switching module determines the PWM signal modulation mode to be SVPWM. The spectrum modulation module sets the fundamental frequency to 49kHz according to the SVPWM mode. The switching frequency jitter depth is ±3.5%, and the switching frequency update speed is 2 switching cycles. After the output power stabilizes above 3.0kW for 5 minutes, the modulation switching module issues a modulation mode switching command for the PWM signal and completes the update of the switching frequency parameters within 2 switching cycles. During this switching process, the inverter's output voltage THD fluctuates slightly from 4.1% to 4.3%.

[0152] 3. Midday Full Load Operation: Solar irradiance reaches 950W / m², inverter output power increases from 7.2-7.8kW (near full load), grid voltage fluctuates (neighboring equipment is being used). At this time, the modulation switching module maintains SVPWM mode to ensure output waveform quality. Simultaneously, the acquisition module monitors the grid voltage dropping from 230V to 225V. The modulation switching module then adaptively adjusts the modulation ratio to adapt to the grid voltage change. The spectrum modulation module maintains a switching frequency jitter depth of ±3.5% and uses a pseudo-random sequence to avoid periodic interference. The fundamental frequency can be 50kHz at this time, matching the grid frequency. When the grid voltage drops sharply (225V→218V), the modulation switching module maintains SVPWM but adjusts the modulation depth. The spectrum modulation module increases the switching frequency jitter depth to ±5% to increase the inverter's EMI stability. During this time, the photovoltaic power generation system does not disconnect from the grid, and the output voltage THD remains at 3.2%.

[0153] 4. Sudden Cloud Cover Impact: When thick clouds pass by, solar irradiance drops sharply from 900W / m² to 200W / m², causing the inverter's output power to decrease from 7.5kW to 1.8kW (within 2 minutes), and the temperature to drop from 32°C to 28°C. The modulation switching module detects an output power fluctuation rate >3kW / min and immediately switches the PWM signal modulation mode to DPWM mode. The spectrum modulation module sets the switching frequency jitter depth to ±8% (maximum value), the fundamental frequency drops to 46kHz, and the noise immunity enhancement mode is activated. As the clouds disperse, the inverter's output power begins to recover. When the output power stabilizes above 2.5kW, the modulation switching module switches the PWM signal modulation mode back to SVPWM mode.

[0154] The following describes the inverter control method using a low-power morning operation scenario. At this time, solar irradiance is low, the inverter's output power is 0.8-1.2kW, and the ambient temperature is 18°C. The inverter's EMC performance must meet Class BEMI standards while maintaining efficiency. The acquisition module continuously acquires the output power, and the modulation switching module determines the current output power status. When the output power is below the 1.5kW threshold, and considering the ambient temperature, the DPWM mode is selected. The DPWM mode, through clamping, continuously connects one phase arm to the positive or negative DC bus in each fundamental frequency cycle, thereby reducing the number of switching operations by approximately 60%. With an ambient temperature of 18°C ​​and good heat dissipation, the DPWM mode can be chosen. The spectrum modulation module receives the DPWM mode instruction from the modulation switching module and adjusts the switching frequency parameters to the corresponding parameters. For example, setting the switching frequency jitter depth to ±7.5% disperses the fundamental and harmonic energy of the switching frequency within this frequency range, thereby reducing interference peaks at any fixed frequency point. Because DPWM itself involves fewer switching cycles, the sources of EMI noise are already reduced. Using a larger switching frequency jitter depth further diffuses the remaining EMI noise, making it easier to meet Class B requirements. A slow random sequence is used, updating the frequency every 5 switching cycles. This avoids rapid frequency changes that could lead to control loop instability (current and voltage loops require time to track frequency changes) and degraded output waveform quality. The slow change also allows for a longer residence time at each frequency point, enabling EMI testing equipment (such as a spectrum analyzer) to effectively record energy diffusion rather than measuring transient spikes caused by rapid changes. The fundamental frequency is 47kHz, avoiding the stringent Class B testing point of 150kHz. This is because the third harmonic at 150kHz is three times that of 50kHz, while the third harmonic at 47kHz is 141kHz, thus avoiding 150kHz. Additionally, 47kHz avoids other sensitive radio frequencies that may exist in residential areas. DPWM is more efficient under light loads, and the slow update of the spread spectrum reduces additional losses caused by frequency changes. Furthermore, lowering the fundamental frequency to 47kHz also reduces switching losses. The final efficiency reaches 96.2%, which is 1.8% higher than the SVPWM mode. The slow frequency update ensures the stability of the control loop and maintains good output current waveform quality.

[0155] Figure 11 This is a schematic diagram illustrating the workflow of a modulation switching module provided in an embodiment of the present invention. Figure 11As shown, initialization can be performed after the modulation switching module starts working. First, initialize the PWM signal modulation mode to SVPWM mode, and simultaneously set the switching threshold for the PWM signal modulation mode, for example, a switching current threshold. Then, sample the inverter's output parameters, which are of the same type as the switching threshold. For example, when the switching threshold is the switching current threshold, the output parameter is the output current, and the absolute value of the output current is calculated. The following explanation uses the output current as the output parameter. Determine if the absolute value of the output current is less than the switching current threshold. If so, determine if the current PWM signal modulation mode is DPWM mode. If the current PWM signal modulation mode is DPWM mode, maintain DPWM mode. If the current PWM signal modulation mode is not DPWM mode, switch the current PWM signal modulation mode to DPWM mode. Then configure the DPWM parameters, set the clamping interval, and update the PWM signal modulation mode. If not, determine if the current mode is SVPWM mode. If the current PWM signal modulation mode is SVPWM mode, maintain the PWM signal modulation mode as SVPWM mode. If the current PWM signal's modulation mode is not SVPWM, switch the current PWM signal's modulation mode to SVPWM. Then configure the DPWM parameters, enable continuous modulation, and update the PWM signal's modulation mode. Then delay and wait to ensure the stability of the switching process. Next, determine if the system containing the inverter is continuously running. If yes, return to the sampling step. If not, end the process.

[0156] Figure 12 This is a schematic diagram illustrating the workflow of a spectrum modulation module provided in an embodiment of the present invention. Figure 12 As shown, the spectrum modulation module can read the fundamental frequency Fb and then the switching frequency jitter depth f1. It then generates a random number Rnd using a pseudo-random number generator. Next, it determines the frequency offset f' = Rnd × f1 based on the switching frequency jitter depth and the random number. Finally, it calculates the switching frequency f = f' + Fb for the current cycle. The switching frequency update rate is then updated, and the system is reconfigured according to the current cycle's switching frequency. After the current switching cycle ends, it checks whether the system containing the inverter continues to operate. If yes, it returns to the random number Rnd generation step. If not, the process ends.

[0157] This invention also provides an energy storage device, which includes an inverter and a controller. The controller is used to control the inverter to implement the inverter control method provided in any embodiment of this invention.

[0158] Specifically, Figure 13 This is a schematic diagram of the structure of an energy storage device provided in an embodiment of the present invention. Figure 13As shown, the PWM signal provided by the controller 100 is amplified into a high-voltage signal by the driver chip 200 and then output to the inverter, specifically to the three-phase inverter bridge in the power main circuit, to control the state of the switching transistors in the three-phase inverter bridge. The DC input source of the power main circuit provides DC power (such as photovoltaic modules, batteries, etc.). The DC-side EMI filter is used to filter out high-frequency noise at the input. The three-phase inverter bridge can consist of six power switching transistors to achieve DC-AC conversion. The AC-side LCL filter is used to filter out high-frequency switching harmonics at the output. The AC grid / load is the final energy output target of the power main circuit. The output power and noise signals acquired by the controller 100 can be provided by a detection and feedback network. For example, as shown... Figure 13 As shown, the detection and feedback network can include DC voltage sensors, AC current sensors, high-frequency noise sensors, and temperature and other sensors. The DC voltage sensor is used to monitor the DC bus voltage in real time. The AC current sensor can sample the output three-phase current. The high-frequency noise sensor can be a critical EMI feedback element for detecting common-mode noise. Temperature and other sensors are used to monitor system status.

[0159] Since the controller in the energy storage device can control the inverter to implement the inverter control method provided in any embodiment of the present invention, it has the same beneficial effects as the inverter control method provided in any embodiment of the present invention, and will not be described again here.

[0160] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. An inverter control method characterized by, The method comprises: acquiring an output power of an inverter; determining a modulation mode of a PWM signal according to the output power, the PWM signal being used to drive the inverter to work; the modulation mode of the PWM signal comprises a discontinuous pulse width modulation mode and a space vector pulse width modulation mode; determining a switching frequency parameter of the inverter according to the modulation mode of the PWM signal, the switching frequency parameter comprising at least one of a switching frequency jitter depth, a switching frequency jitter mode and a switching frequency update speed; generating the PWM signal based on the switching frequency parameter.

2. The inverter control method according to claim 1, characterized by, The determining of the switching frequency parameter of the inverter according to the modulation mode of the PWM signal comprises: if the modulation mode of the PWM signal is the discontinuous pulse width modulation mode, performing one or more of increasing the switching frequency jitter depth, reducing the switching frequency update speed and switching the jitter mode to a random jitter mode; if the modulation mode of the PWM signal is the space vector pulse width modulation mode, performing one or more of reducing the switching frequency jitter depth, increasing the switching frequency update speed and switching the jitter mode to a pseudo-random jitter mode.

3. The inverter control method according to claim 1, characterized by, The determining of the switching frequency parameter of the inverter according to the modulation mode of the PWM signal comprises: if the modulation mode of the PWM signal is the discontinuous pulse width modulation mode, increasing the switching frequency jitter depth, reducing the switching frequency update speed and switching the jitter mode to a random jitter mode; if the modulation mode of the PWM signal is the space vector pulse width modulation mode, reducing the switching frequency jitter depth, increasing the switching frequency update speed and switching the jitter mode to a pseudo-random jitter mode.

4. The inverter control method of claim 1, wherein The inverter control method further comprises: determining a fundamental frequency of the switching frequency according to the output power; after the determining of the fundamental frequency of the switching frequency according to the output power, the method further comprises: if the modulation mode of the PWM signal is the discontinuous pulse width modulation mode, reducing the fundamental frequency; if the modulation mode of the PWM signal is the space vector pulse width modulation mode, increasing the fundamental frequency.

5. The inverter control method of claim 1, wherein The inverter control method further comprises: acquiring a noise signal of the inverter; forming an EMI feedback signal according to the noise signal; optimizing the switching frequency parameter according to the EMI feedback signal.

6. The inverter control method according to claim 5, characterized by, The forming of the EMI feedback signal according to the noise signal comprises: forming an initial EMI feedback signal according to the noise signal; optimizing the initial EMI feedback signal according to the modulation mode of the PWM signal and the switching frequency parameter to form the EMI feedback signal.

7. The inverter control method according to claim 5, characterized by, Before the generating of the PWM signal based on the switching frequency parameter, the method further comprises: if the switching frequency is greater than the fundamental frequency, reducing a rising edge time or a falling edge time of the PWM signal; if the switching frequency is less than the fundamental frequency, increasing the rising edge time or the falling edge time of the PWM signal.

8. The inverter control method according to claim 7, characterized by, After the forming of the EMI feedback signal according to the noise signal, the method further comprises: if the EMI feedback signal is greater than a preset EMI value, setting the modulation mode of the PWM signal to the discontinuous pulse width modulation mode; The switching frequency jitter depth is set as a maximum preset value in a preset jitter range. The rising edge time or the falling edge time of the PWM signal is set as a maximum preset time in a preset time range.

9. The method of claim 1, wherein, The modulation mode of the PWM signal is determined according to the output power, including: a plurality of output powers in a preset time period are obtained; a change rate of the output power is determined based on the plurality of output powers; if the output power at the current time is greater than or equal to a first preset value, and / or the rising change rate of the output power is greater than or equal to a second preset value, it is determined that the modulation mode of the PWM signal is the space vector pulse width modulation mode; if the output power at the current time is less than or equal to a third preset value, and / or the falling change rate of the output power is greater than or equal to a fourth preset value, it is determined that the modulation mode of the PWM signal is the discontinuous pulse width modulation mode; wherein the third preset value is less than the first preset value.

10. An energy storage device, characterized by, The inverter and a controller are included, and the controller is used to control the inverter to realize the inverter control method in any one of claims 1-9.

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