新型低电压吊扇相比传统的交流感应电动机吊扇设计节省了大量能源

Optimize Your Fan Solution

Changing from a high-voltage, single-phase ACIM to a lower-voltage three-phase PMSM/BLDC motor requires a two-stage power conversion circuit. First, a fly-back rectification circuit converts the 90−265 VAC input power into an intermediate DC voltage. This voltage is used to spin a BLDC or PMSM motor, so it should be in a voltage range that matches the intended motor. In our ceiling fan reference design, the intermediate voltage is set to 32 volts.

It’s also important that the fly-back circuit keep a high Power Factor Correction (PFC) ratio. Even during low fan speed conditions, our reference design keeps the PFC at 0.9 or above. Doing this reduces the load on the power delivery system and avoids penalties or extra charges that could apply if the PFC drops below that.

The intermediate 32 volts are then dropped to 10 volts by an MCP16331 peak current mode PWM DC/DC converter. This is used to efficiently power the three MIC4605 half-bridge MOSFET gate drivers, which switch the six MOSFETs on and off as directed by a dsPIC® Digital Signal Controller (DSC) PWM outputs. The 10 volts are further dropped to 3.3V by a highly efficient MIC5205 Low Drop-Out (LDO) voltage regulator to power the dsPIC DSC motor controller itself.