US 9,112,439 B2 · Method and circuit arrangement for detecting motor load without sensors and for controlling motor current according to load for a stepper motor

Abstract

A method and a circuit arrangement are provided in which a mechanical load applied to the motor shaft or a load angle of the motor can be detected without sensors in a stepper motor. This is achieved substantially based on the fact that the load or the load angle creates a mutually induced voltage (back EMF) in the motor coils and the load or the load angle is detected by determining the phase shift of the motor voltage at at least one of the motor coil relative to the coil current at said motor coil connection, the phase shift being caused by the mutually induced voltage. A method and a circuit arrangement are also provided wherein the motor current of a stepper motor can be controlled according to load angle in such a way that the current consumption of the motor is relatively low.

Claims18

Dependent claims

Method for sensor-free detection of a motor load angle or load value in a stepper motor, comprising:

generating from supplied target coil currents by a chopper process chopper switch signals,
impressing, by a motor supply voltage which is switched by the chopper switch signals the target coil currents into motor coil terminals,
generating, via the load angle and the load value, respectively, a counter-induced voltage in the motor coils,
determining a temporal intersecting point of the courses of two motor voltages at two motor coil terminals,
detecting a phase shift, caused by the counter-induced voltage, between one of these two motor voltages and the coil current at this motor coil terminal at the moment of the occurrence of the intersecting point,
and determining the load angle and the load value, respectively, on the basis of the phase shift.

3 more elements

Dependencies are inferred from the claim text.

Method and circuit arrangement for detecting motor load without sensors and for controlling motor current according to load for a stepper motor

Life of this patent

Method and circuit arrangement for detecting motor load without sensors and for controlling motor current according to load for a stepper motor

Life of this patent

Abstract

Claims18