Abstract: The present disclosure discloses acoustic devices. The acoustic device may include a diaphragm; a housing configured to accommodate the diaphragm and form a first acoustic cavity and a second acoustic cavity respectively corresponding to a front side and a rear side of the diaphragm, wherein the diaphragm radiates sounds to the first acoustic cavity and the second acoustic cavity, respectively, and the sounds are guided through a first acoustic hole coupled with the first acoustic cavity and a second acoustic hole coupled with the second acoustic cavity, respectively; and a sound absorption structure, wherein the sound absorption structure is coupled with the second acoustic cavity and is configured to absorb the sound transmitted to the second acoustic hole through the second acoustic cavity in a target frequency range, the target frequency range including a resonant frequency of the second acoustic cavity.

Abstract: The present application disclosed a magnetic levitation system, and the magnetic levitation system includes a stator, a rotor, and a magnetic coupling mechanism; the stator includes a stator winding mechanism for controlling the rotor to move away from or close to the axis direction of the stator. The magnetic coupling mechanism includes magnetic sources, and the magnetic coupling mechanism is magnetically coupled with the rotor through the magnetic sources to drive the rotor to rotate around the axis direction of the stator. The magnetic levitation system decouples the magnetic circuit that drives the rotor to move from the magnetic circuit that drives the rotor to rotate, so as to reduce control difficulty, enhance stability, and reduce torque fluctuations.

Abstract: A power generation performance evaluation method and an apparatus thereof for a generator set are provided according to the embodiments of the present invention, which are related to the technical field of power apparatuses and are able to provide an accurate evaluation for the power generation performance of the generator set in combination with historical operation data of the generator set.

Abstract: Disclosed is a passive converter for a drive device of a switched reluctance motor (SRM), in which high demagnetization voltage for the SRM is provided. The converter includes a rectifier which smoothes input voltage to supply DC voltage, a boost circuit connected with the rectifier, and an asymmetric converter connected with the boost circuit, and the boost circuit includes first to third diodes and first and second capacitors. The high demagnetization voltage is generated at current duration of a single phase or poly-phase SRM by using the passive converter for the drive device of the SRM, so that the driving efficiency and the output power of the SRM can be increased.

Abstract: Disclosed is an active boost power converter for driving a single-phase SRM, capable of rapidly establishing excitation current in the excitation mode and reducing tail current and negative torque in the demagnetization mode under the high-speed operation of the SRM. The active boost power converter includes a boost module and a converter module connected to the boost module. The boost module includes first and second capacitors, first and second diodes and a switch device turned on/off to connect the first and second capacitors to each other in series or parallel. The switch device includes an insulated gate bipolar transistor (IGBT). The power converter is operated with first and second input modes and first and second output modes. Voltage of the first capacitor is equal to dc-link voltage and first and second capacitors are controlled to be operated in series or parallel by simply controlling the IGBT.

Abstract: Disclosed is a passive converter for a drive device of a switched reluctance motor (SRM), in which high demagnetization voltage for the SRM is provided. The converter includes a rectifier which smoothes input voltage to supply DC voltage, a boost circuit connected with the rectifier, and an asymmetric converter connected with the boost circuit, and the boost circuit includes first to third diodes and first and second capacitors.