Elmos Semiconductor Ag

Elmos Semiconductor Se

Jörg Hartzsch

A method for controlling an electric motor including a mechanical commutator, includes determining points in time at which commutation takes place by a sensor or without a sensor. The method further includes controlling the electric motor by a supply voltage signal having a sequence of pulses. The method further includes modulating the supply voltage signal by a modulation signal to reduce the magnitude of the supply voltage signal at the commutation points in time.

Method for controlling an electric motor having a mechanical commutator

In a method for generating a blocking moment in a standstill state of an electrically commutated electric motor having at least two windings, on which electric motor a possibly varying load moment acts from outside in the standstill state, first, a blocking current is supplied at a maximum value into a first winding. This blocking current is successively reduced to, possibly, a minimum value. From that moment the inductivity of the electric motor is controlled, namely by controlling the blocking current if the control deviation between the actual value and the set value of the inductivity exceeds a predetermined threshold value. Thereby, it is possible to control the blocking current in an adaptive manner insofar as, despite a varying load moment, the standstill state of the electric motor can be maintained by varying the blocking current.

Adaptive hold current for electric motors

A method for obtaining an indication of a faulty load condition of a multi-phase electric motor includes: (a) starting, a time measurement unit, (b) measuring a recirculation time interval for as long as a current that continues to flow has a magnitude larger than a threshold value, (c) continuing, in case the recirculation time interval is not terminated during the switch-off interval, the time measurement at least in a next switch-off interval, (d) repeating, for additional switch-off intervals the steps (a), (b), and (c) for respective motor phases, (e) comparing (1) the measured recirculation time intervals for respective motor phases with each other and/or (2) for one motor phase in sequential succession with each other and/or (3) with the expectation value of the respective motor phase, and (f) determining, based on a deviation, the indication of the faulty load condition.

Faulty load detection for multi-phase electric motor

An electric motor is electrically commutated with the aid of circuitry, in which the phase current experiences a zero crossing at certain time points per motor phase. Owing to the inductive load portion, the time of said zero crossing of a phase current occurs at different times to the time of the zero crossing that would arise with purely ohmic loads. Without a faulty load condition, the time of said zero crossing is within an expected value range (e.g., expected time window) which can be determined by the circuitry, the ambient conditions and by diverse motor parameters. During occurrence of the a high-side and/or low-side phase connection, it is determined whether and when the current through the switched-on high-side of low-side switch becomes greater or smaller than a predeterminable threshold wherein said time measurement can extend over one or more PWM cycles.

A method for detecting blockages of unipolar stepper motors by analyzing the motor current supply, comprising impressing a current into one or more motor windings using a controllable switch, wherein the switch selectively connects a respective motor winding connection to a supply voltage connection and wherein the connections of each motor winding lying at a common potential are permanently connected to a second supply voltage connection, wherein a current feed variant has phases between the switching of the motor windings, in which phases the motor winding connections are switched with high resistance; detecting the voltage at a motor winding connection at least for the high-resistance phase and comparing the voltage to a threshold; detecting a time interval for which the voltage is greater than the threshold; comparing interval lengths for several motor winding connections, and detecting a blockage based on the comparisons of interval lengths.

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Dortmund, Germany

Jörg Hartzsch