Abstract: A control method and control circuit for a switched-mode power supply (SMPS) and a control chip are disclosed. The SMPS is switched between different operating modes based on different levels of its output voltage. When the output voltage is lower than a first reference and the difference between it and the first reference exceeds a threshold, an operating frequency of a power transistor and output voltage are controlled to satisfy a proportional relationship defined by an associated slope. When the output voltage is lower than the first reference and the difference between it and the first reference is below the threshold, the power transistor is controlled to operate at a fixed frequency. When the output voltage is higher than the first reference, the power transistor is controlled to operate at a variable frequency.

Abstract: An adjustment-facilitating vibrating mill includes a base, a grinding cylinder, and a vibrating motor. An elastic mechanism is arranged on the base. The grinding cylinder is fixedly connected to the elastic mechanism. The vibrating motor is arranged on the grinding cylinder. Two sides of the vibrating motor are provided with eccentric mechanisms; each eccentric mechanism includes a fixed eccentric block, an adjustment motor, and an adjustable eccentric block. The fixed eccentric block sleeves an output shaft of the vibrating motor. The adjustment motor is connected to the fixed eccentric block through a mounting seat. The adjustable eccentric block is connected to the adjustment motor through a transmission mechanism. According to the vibrating mill, an included angle between the adjustable eccentric block and the fixed eccentric block is adjusted using the adjustment motor and the transmission mechanism, so that an exciting force can be adjusted without removing the vibrating motor.

Abstract: A module level power electronics (MLPE) photovoltaic system and a method for photovoltaic string control are provided. The method is applied to a control unit in the MLPE photovoltaic system. The control unit detects an output current of each photovoltaic string in the MLPE photovoltaic system, and then controls, for photovoltaic strings connected in parallel to a same inverter in the MLPE photovoltaic system, a voltage of a photovoltaic string with larger output current to be reduced, or controls a voltage of a photovoltaic string with smaller output current to be increased, so that backflow current can be reduced to preset range tolerable for MLPE device. The method is from a perspective of the MLPE photovoltaic system, the backflow current is limited by controlling voltage change of associated photovoltaic string without additional hardware cost, effectively protecting MLPE device in the MLPE photovoltaic system.

Abstract: The Disclosed in the present application are a power electronic device on a direct-current side of a photovoltaic system, and a test system and a control method therefor, achieving a simple, fast, and low-cost functional test on the power electronic device during a production process or a troubleshooting process of the power electronic device on the direct-current side of the photovoltaic system. The power electronic device is used for detecting a fluctuation of an electric signal parameter of an input end of the power electronic device; when the fluctuation meets a preset condition, the device is switched from a limited output state to a non-limited output state; the fluctuation of the electric signal parameter of the input end is generated by applying a disturbance to the input end of the power electronic device on the direct-current side of the photovoltaic system by a direct-current power supply having a disturbance output.

Abstract: A module level power electronics (MLPE) photovoltaic system and a method for photovoltaic string control are provided. The method is applied to a control unit in the MLPE photovoltaic system. The control unit detects an output current of each photovoltaic string in the MLPE photovoltaic system, and then controls, for photovoltaic strings connected in parallel to a same inverter in the MLPE photovoltaic system, a voltage of a photovoltaic string with larger output current to be reduced, or controls a voltage of a photovoltaic string with smaller output current to be increased, so that backflow current can be reduced to preset range tolerable for MLPE device. The method is from a perspective of the MLPE photovoltaic system, the backflow current is limited by controlling voltage change of associated photovoltaic string without additional hardware cost, effectively protecting MLPE device in the MLPE photovoltaic system.