Abstract: The present disclosure provides a multi-level converter with triangle topology and control method thereof, related to the technical field of multi-level converters. In the converter, n DC capacitors connected in series form a vertical edge of a triangle and are as a DC bus, n switching tubes connected in series form a bevel edge of the triangle, switching tubes each connected between a neutral point of the DC bus corresponding to each layer and a point for connecting the switching tube on the bevel edge form a horizontal edge. Each time the layer is expanded by one, the number of levels increases by one. When a voltage across each capacitor is E, an AC output terminal Xn may output a total of n+1 levels.

Abstract: A loudspeaker module and an electronic apparatus are disclosed, the loudspeaker module comprises a housing, a loudspeaker unit and a barrier rib body; the loudspeaker unit is provided in an inner cavity of the housing and divides the inner cavity of the housing into a front acoustic cavity and a rear acoustic cavity, the rear acoustic cavity is filled with sound-absorbing particles, and a cavity wall of the rear acoustic cavity is provided with a leakage hole. The barrier rib body is provided in the rear acoustic cavity, at least a part of the barrier rib body faces the leakage hole, and the distance between the leakage hole and the part of the barrier rib body facing the leakage hole is less than the size of the sound-absorbing particles. The technical solution of thc prcscnt disclosure can reduce the occurrence of the situation where the sound-absorbing particles block the leakage hole.

Abstract: A sound generator, which comprises: a housing, a vibration system and a magnetic circuit system. The vibration system and the magnetic circuit system are sequentially accommodated and fixed at a first end of the housing from top to bottom; the magnetic circuit system is provided with a rear sound hole; the housing comprises a first portion corresponding to the vibration system and the magnetic circuit system, and a second portion integrally extending downward from the first portion beyond a bottom surface of the magnetic circuit system; a second end portion of the housing is integrally provided with a housing bottom wall or separately mounted with a lower cover plate; and a rear cavity which is in communication with the rear sound hole is formed between the second portion of the housing, the bottom surface of the magnetic circuit system, and the housing bottom wall or the lower cover plate.

Abstract: The present disclosure provides a multi-level converter with triangle topology and control method thereof, related to the technical field of multi-level converters. In the converter, n DC capacitors connected in series form a vertical edge of a triangle and are as a DC bus, n switching tubes connected in series form a bevel edge of the triangle, switching tubes each connected between a neutral point of the DC bus corresponding to each layer and a point for connecting the switching tube on the bevel edge form a horizontal edge. Each time the layer is expanded by one, the number of levels increases by one. When a voltage across each capacitor is E, an AC output terminal Xn may output a total of n+1 levels.

Abstract: An embodiment of the present invention provides a sound generating device which comprises a housing, wherein a sound generating unit is mounted in the housing, a closed rear cavity is formed between the sound generating unit and the housing, and the sound generating unit is provided with a rear sound hole in communication with the rear cavity, wherein the sound generating unit comprises a magnetic circuit system, an expandable-capacity cavity being provided on the magnetic circuit system, and the expandable-capacity cavity acting as part of the rear cavity to increase a volume of the rear cavity.

Abstract: The present disclosure provides a single carrier based multilevel modulation method, a single carrier based multilevel modulation device, and a storage medium. In each control period, a modulated wave value corresponding to each of n switch pairs is obtained according to a reference voltage to obtain n modulated wave values, a triangular carrier having an amplitude of n is generated and compared with each of the n modulated wave values to obtain control signals for each of the n switch pairs, and for each phase, the control signals are input to the corresponding switch pairs of the phase bridge.

Abstract: A sound generator, which comprises: a housing, a vibration system and a magnetic circuit system. The vibration system and the magnetic circuit system are sequentially accommodated and fixed at a first end of the housing from top to bottom; the magnetic circuit system is provided with a rear sound hole; the housing comprises a first portion corresponding to the vibration system and the magnetic circuit system, and a second portion integrally extending downward from the first portion beyond a bottom surface of the magnetic circuit system; a second end portion of the housing is integrally provided with a housing bottom wall or separately mounted with a lower cover plate; and a rear cavity which is in communication with the rear sound hole is formed between the second portion of the housing, the bottom surface of the magnetic circuit system, and the housing bottom wall or the lower cover plate.

Abstract: An embodiment of the present invention provides a sound generating device which comprises a housing, wherein a sound generating unit is mounted in the housing, a closed rear cavity is formed between the sound generating unit and the housing, and the sound generating unit is provided with a rear sound hole in communication with the rear cavity, wherein the sound generating unit comprises a magnetic circuit system, an expandable-capacity cavity being provided on the magnetic circuit system, and the expandable-capacity cavity acting as part of the rear cavity to increase a volume of the rear cavity.

Abstract: The present disclosure provides a single carrier based multilevel modulation method, a single carrier based multilevel modulation device, and a storage medium. In each control period, a modulated wave value corresponding to each of n switch pairs is obtained according to a reference voltage to obtain n modulated wave values, a triangular carrier having an amplitude of n is generated and compared with each of the n modulated wave values to obtain control signals for each of the n switch pairs, and for each phase, the control signals are input to the corresponding switch pairs of the phase bridge.

Abstract: A terminal access scheduling method is provided. The method is applied to a scheduling server and includes performing grouping on terminals that need access to obtain multiple terminal groups; and performing cluster division on machines providing resources for access to obtain multiple machine clusters. The method also includes obtaining resource demands of the terminal groups, available resources of the machine clusters, and access quality between the terminal groups and the machine clusters; obtaining coverage ratios of the machine clusters to the terminal groups according to the resource demands of the terminal groups, the available resources of the machine clusters, and the access quality; and performing access scheduling for the terminals according to the coverage ratios.

Abstract: A method and a device for voltage balancing of DC bus capacitors of an NPC four-level inverter are disclosed. The method includes: determining an optimal zero-sequence voltage, determining an actual reference voltage of each phase based on the optimal zero-sequence voltage; comparing respectively three preset carrier signals with the actual reference voltage of each phase to obtain three first control signals; determining three duty-cycle adjustment values based on a voltage of the intermediate bus capacitor; adjusting correspondingly the three first control signals based the three duty-cycle adjustment values to obtain three second control signals; inputting correspondingly the three second control signals to three first switches of an upper bridge corresponding to each phase; and inputting correspondingly complementary signals of the three second control signals to three second switches of a lower bridge corresponding to each phase.

Abstract: A miniature sounder is mounted in an electronic terminal and comprises a front cover and a housing that are combined together. A vibration system and a magnetic circuit system are accommodated in a space formed by the front cover and the housing in a surrounding manner. Two electrical connection members used for being electrically connected to the vibration system and the electronic terminal is disposed on the housing. An antenna of the electronic terminal is fixedly on the front cover, and the antenna is electrically connected to one of the two electrical connection members, and is electrically connected to a circuit of the electronic terminal by means of the electrical connection members.

Abstract: A method and a device for voltage balancing of DC bus capacitors of an NPC four-level inverter are disclosed. The method includes: determining an optimal zero-sequence voltage, determining an actual reference voltage of each phase based on the optimal zero-sequence voltage; comparing respectively three preset carrier signals with the actual reference voltage of each phase to obtain three first control signals; determining three duty-cycle adjustment values based on a voltage of the intermediate bus capacitor; adjusting correspondingly the three first control signals based the three duty-cycle adjustment values to obtain three second control signals; inputting correspondingly the three second control signals to three first switches of an upper bridge corresponding to each phase; and inputting correspondingly complementary signals of the three second control signals to three second switches of a lower bridge corresponding to each phase.

Abstract: A terminal access scheduling method is provided. The method is applied to a scheduling server and includes performing grouping on terminals that need access to obtain multiple terminal groups; and performing cluster division on machines providing resources for access to obtain multiple machine clusters. The method also includes obtaining resource demands of the terminal groups, available resources of the machine clusters, and access quality between the terminal groups and the machine clusters; obtaining coverage ratios of the machine clusters to the terminal groups according to the resource demands of the terminal groups, the available resources of the machine clusters, and the access quality; and performing access scheduling for the terminals according to the coverage ratios.

Abstract: A miniature sounder is mounted in an electronic terminal and comprises a front cover and a housing that are combined together. A vibration system and a magnetic circuit system are accommodated in a space formed by the front cover and the housing in a surrounding manner. Two electrical connection members used for being electrically connected to the vibration system and the electronic terminal is disposed on the housing. An antenna of the electronic terminal is fixedly on the front cover, and the antenna is electrically connected to one of the two electrical connection members, and is electrically connected to a circuit of the electronic terminal by means of the electrical connection members.