Abstract: The object of the present application is to ensure the security of a device when a precharging relay is not closed and a load current passes through a precharging resistor, so as to ensure the customer's security. Provided is a security control method for a system with a precharging circuit, comprising: giving out an error alarm and stopping operating the system when the number of times of undervoltage of a precharging circuit achieves m times and the duration between the first undervoltage and the mth undervoltage is less than or equal to ? seconds, where m and ? are positive integers. Compared with the previous method, the present invention has the following advantages of no danger of combustion and high reliability; and cost saving and no need of adding additional hardware.

Abstract: A heat-dissipating structure for a variable speed drive (VSD), a VSD device having the heat-dissipating structure, and a method for controlling the heat-dissipating structure. The heat-dissipating structure comprises: an electronic element array, having a first end and an opposite second end, electronic elements in the array producing heat during operation; a heat-dissipating fan, disposed at the first end of the array and used to conduct cooling air to flow between the first end and the second end to cool the electronic elements in the array; and a control apparatus, for controlling operation of the fan, the control apparatus controlling the fan so that the fan rotates at a first rotation direction within a first time period to conduct the cooling air to flow from the second end to the first end, and rotates at a second rotation direction contrary to the first rotation direction within a second time period to conduct the cooling air to flow from the first end to the second end.

Abstract: A heat-dissipating structure for a variable speed drive (VSD), a VSD device having the heat-dissipating structure, and a method for controlling the heat-dissipating structure. The heat-dissipating structure comprises: an electronic element array, having a first end and an opposite second end, electronic elements in the array producing heat during operation; a heat-dissipating fan, disposed at the first end of the array and used to conduct cooling air to flow between the first end and the second end to cool the electronic elements in the array; and a control apparatus, for controlling operation of the fan, the control apparatus controlling the fan so that the fan rotates at a first rotation direction within a first time period to conduct the cooling air to flow from the second end to the first end, and rotates at a second rotation direction contrary to the first rotation direction within a second time period to conduct the cooling air to flow from the first end to the second end.

Abstract: The object of the present application is to ensure the security of a device when a precharging relay is not closed and a load current passes through a precharging resistor, so as to ensure the customer's security. Provided is a security control method for a system with a precharging circuit, comprising: giving out an error alarm and stopping operating the system when the number of times of undervoltage of a precharging circuit achieves m times and the duration between the first undervoltage and the mth undervoltage is less than or equal to ? seconds, where m and ? are positive integers. Compared with the previous method, the present invention has the following advantages of no danger of combustion and high reliability; and cost saving and no need of adding additional hardware.