Counter electromotive force detection circuit of brushless direct current motor and range hood applying counter electromotive force detection circuit

Abstract

The invention discloses a counter electromotive force detection circuit of a brushless direct current motor and a range hood applying the counter electromotive force detection circuit. The counter electromotive force detection circuit of the brushless direct current motor comprises an input comparison module, a conversion module and a latch output module. The input comparison module compares a busvoltage with a back electromotive force and transmits a comparison result to the latch output module, and the latch output module latches the comparison result of the input comparison module after receiving a trigger signal of the conversion module and finally outputs the comparison result. According to the counter electromotive force detection circuit of the brushless direct current motor, a hardware circuit detection method is used for replacing a software algorithm, internal resources of the MCU processor are released, MCU space resources are provided for expansion of other functions except motor control, and the cost is reduced; meanwhile, the hardware processing speed is higher than that of software processing, a zero-crossing detection result is directly outputted by hardware without a software algorithm, the complexity of software design is greatly simplified and the real-time performance of processing is improved.

Description

technical field [0001] The invention belongs to the technical field of brushless direct current motors, and in particular relates to a counter electromotive force detection circuit of a brushless direct current motor and a range hood using the same. Background technique [0002] At present, brushless DC motors are widely used in range hood products. In order to reduce the manufacturing cost of motors and improve reliability, brushless DC motors without Hall sensors are becoming a trend. There is no Hall sensor inside the motor, which means that the motor control software needs to perform very precise timing control on the commutation time of the motor, which undoubtedly increases the burden on the MCU processor. [0003] In the electronic control software, the general practice is to compare the zero-crossing by sampling the bus voltage Vbus and the counter electromotive force Vemf. When it is detected that Vemf≥1 / 2Vbus or Vemf≤1 / 2Vbus, it means that a zero-crossing event has...

AI Technical Summary

Problems solved by technology

Obviously, on a multifunctional range hood, too much MCU processor resources are consumed in the motor control function, which will inevitably lead to too few resources reserved for other functions to be realized, or affect the subsequent function expansion of the product. If the internal More resource-rich MCU processors will result in high cost

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