Patent ID: 9520822
Filing Date: 2016-12-13
CPC Classification: H02P

Claim Text:
1. A circuit for driving an Eccentric Rotating Mass (“ERM”) motor, the circuit comprising: an input terminal; a driver having an input and an output; a feedback amplifier having an input coupled to the output of the driver, and an output; a summer circuit having first and second inputs, the first input coupled to the input terminal, the summer circuit further having an output coupled to the input of the driver; a first switch having a first terminal coupled to the first input of the summer circuit, and a second terminal coupled to the output of the summer circuit; a second switch having a first terminal coupled to the output of the feedback amplifier, and a second terminal coupled to the second input of the summer circuit; and a controller having a first input coupled to the output of the driver, a second input coupled to the input terminal, and an output coupled to respective control inputs of the first and second switches, wherein the controller is configured to receive an input signal from the input terminal, and a back electromechanical force (EMF) signal from the motor, wherein the controller is configured to operate the circuit in a closed loop mode when the back EMF signal is less than a lower threshold value and a difference between a value of the input signal and the back EMF signal is positive, wherein the controller is configured to operate the circuit in an open loop mode when the back EMF signal is greater than a higher threshold value and the difference between the value of the input signal and the back EMF signal is positive, wherein the controller is configured to operate the circuit in a previous one of the open loop and closed loop modes when the back EMF signal is between the higher and lower threshold values and the difference between the value of the input signal and the back EMF signal is positive, wherein the controller is configured to operate the circuit in the closed loop mode when the difference between the value of the input signal and the back EMF signal is negative, wherein the controller is configured to operate the circuit in the closed loop mode by opening the first switch and closing the second switch, and wherein the controller is configured to operate the circuit in the open loop mode by closing the first switch and opening the second switch.