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  • MC34937 Typical Connection for 3 Phase Motor

  • Created: Oct 20, 2015

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This reference design is a typical connection for MC34937APEK to a 3-phase brushless DC motor. The supply of a motor is a DC source, which has been controlled by the MOSFETs. The MOSFETs function as switches for the input signal for the motor. The DC signal is converted to a PWM signal that is fed to the three input ports of the motor. The signal in each port is out of phase to each other, therefore the supply voltage for the motor is already in 3 phases. The switching of the MOSFETs is controlled by MC34937, a three-phase field effect transistor pre-driver. It provides the MOSFETs the signal when to switch on or off. The device ensures the timing of the switching in order to make the three input signals become out of phase to each other thus, emulating a 3-phase AC signal.

The MC34937APEK has six direct input control signals. An MCU can be connected to it so that the speed and triggering can be controlled. The device supports a direct 3.3V and 5.0V logic interface to MCUs. It has an extended supply voltage ranging from 6V to 58V and is capable to drive an external FET gate with >1.0A protection. The device has an integrated overcurrent, desaturation, and phase fault-detection. It is also immune against positive or negative transient voltage spikes on the gate driver.

The typical application for this device is for 12V - 48V 3-phase BLDC motors and permanent magnet synchronous motors (PMSM). It can also be used to control the motors on E-bikes, hospital beds, electric wheel chairs, and the like. For industrial use, it can drive the motors in inflation pumps and industrial fans.



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