Elevator Hold Cut-off Switch
Elevator hold cut-off Switch
As the name implies, switching power supplies use electronic switching devices (such as transistors, FETs, thyristors, etc.).
Through the control circuit, the electronic switching device is constantly turned "on" and "off", so that the electronic switching device performs pulse modulation on the input voltage, thereby achieving DC / AC, DC / DC voltage conversion, and the output voltage adjustable and automatic Regulated.
The switching power supply generally has three operating modes: frequency, fixed pulse width mode, fixed frequency, variable pulse width mode, variable frequency and pulse width mode. The former work mode is mostly used for DC/AC inverter power supply, or DC/DC voltage conversion; the latter two work modes are mostly used for switching power supply. In addition, the switching power supply output voltage also has three operating modes: direct output voltage mode, average output voltage mode, and amplitude output voltage mode. Similarly, the former work method is mostly used for DC/AC inverter power supply, or DC/DC voltage conversion; the latter two work methods are mostly used for switching power supply.
According to the way the switching devices are connected in the circuit, the switching power supply can be roughly divided into three major categories: series-connected switching power supplies, parallel-connected switching power supplies, and transformer-type switching power supplies. Among them, the transformer-type switching power supply (hereinafter referred to as the transformer switching power supply) can be further divided into: push-pull, half-bridge, full-bridge and other types; according to the transformer's excitation and output voltage phase, can be divided into: forward excitation , Flyback, single-excited, and double-excited, etc.; if it is divided from the use, it can be divided into more categories.