Dr. Johannes Heidenhain Gmbh

Johannes Heidenhain Gmbh

Norbert Huber

Franz Ritz

Simon Graf

Alfons Ernst

Walter Schmitt

Georg Zehentner

Markus Schoenlinner

Eugen Kellner

Markus SCHÖNLINNER

A method for diagnosing a frequency converter is used for a frequency converter having a positive and negative DC link voltage which is applied via bridges of switching elements in an alternating sequence to phases of a motor. Pulse width modulation (PWM) signals drive the switching elements for a respective one of the phases and current sensors capture phase currents. In a step a), PWM signals are applied as test patterns to the switching elements. In a step b), sensor signals of the current current sensors are picked up. In a step c), the sensor signals are evaluated by ascertaining a presence of the DC link voltage upon a displacement current being recognized in the sensor signals.

Method for diagnosing a frequency converter

In an inverter and a method for operating an inverter, the inverter includes a step-up converter circuit, a dynamic intermediate circuit, and a step-down converter circuit for converting a direct voltage of a direct voltage generator or string into an alternating voltage for supplying a network. The step-up converter circuit increases the direct voltage if the latter is lower than a peak-to-peak maximum of the network voltage, and the step-down converter circuit lowers a dynamic intermediate circuit voltage, as needed, to a lower voltage currently required in the network. The step-up converter circuit dynamically increases the direct voltage to the value currently required in the network and in the process temporarily supplies an approximately sinusoidal voltage curve for the intermediate circuit voltage.

Method for operating an inverter, and inverter

In a protective circuit for a converter having a plurality of phases, for each phase current of the phases, a signal proportional to the respective phase current is applied to a transformer circuit that, below and in the area of a limiting frequency, functions as a low-pass filter with the limiting frequency, and above the limiting frequency, functions as a divider. The outputs of the transformer circuit are applied to a maximum generator for forming the absolute value maximum. This maximum is fed to a comparator in which the maximum is compared to a reference value.

Protective circuit for a converter

A converter includes a time-delay circuit for a PWM signal, applied to input of the time-delay circuit, by which rising edges of the PWM signal are delayed by an ON delay and falling edges of the PWM signal are delayed by an OFF delay, in order to form a drive signal, available at the output of the time-delay circuit, for a semiconductor switch element. The time-delay circuit includes two resistors, two capacitors, a diode and a comparator, and is therefore particularly easy to implement.

Converter having a time-delay circuit for PWM signals

The voltage of the intermediate circuit of a frequency converter is monitored, while the intermediate circuit is charged via charging resistors. When the voltage has not reached at least a reference voltage during a specific time constant, the charging process is interrupted prematurely. The reference voltage is selected to be considerably lower than the operating voltage of the intermediate circuit. The reference voltage may be less than half of the operating voltage of the intermediate circuit.

Protective circuit for a frequency converter

A method for error detection in a drive mechanism, having a multiphase electric motor and a converter connected upstream thereof, wherein the converter controls voltages of individual phases of the electric motor, and individual phase currents in the individual phases of the electric motor each extend periodically. The method includes measuring a phase current of the electric motor at a predetermined point of a respective period, simultaneously varying a voltage that is associated with the measured phase current and evaluating a measured value of the measured phase current as a function of the voltage that is associated with the measured phase current.

Method for error detection in a drive mechanism

A charging circuit for a frequency converter having a first feed line with a first constant current source therein and a second feed line with a second constant current source therein. An intermediate circuit capacitor connected between the first feed line and the second feed line, wherein the first constant current source that limits a charging current of the intermediate circuit capacitor. An electronic control device that controls both the first constant current source and the second constant current source in parallel.

Charging circuit for a frequency converter

A converter with a damping mechanism for preventing resonances that includes a rectifier, an inverter and an intermediate circuit which connects the rectifier to the inverter. The intermediate circuit includes a first conductor connected to a first potential, a second conductor connected to a second potential that is different than said first potential and a current-compensated choke looped into the first conductor and the second conductor. The current-compensated choke includes a first winding and a second winding, wherein a first current flowing from the rectifier to the inverter flows through the first winding and a second current flowing back from the inverter to the rectifier flows through the second winding.

Converter with damping mechanism for the avoidance of resonances

A method for ground potential monitoring of a rectifier drive, having a capacitor which is connected with a voltage source via a switching device. The method including applying a test voltage between a connector of a capacitor of a rectifier drive and a mass or ground potential prior to connecting the rectifier drive with a voltage source that is connected with the capacitor via a switching device. The method also includes releasing the switching device if a potential of the connector changes by a predetermined amount after the applying the test voltage.

Method for monitoring the ground potential of a rectifier drive

A circuit arrangement allows a converter to be operated with supply voltages oscillating within broad limits. The intermediate circuit voltage of the converter is controlled to avoid unacceptably high currents, so that the intermediate circuit voltage is always higher than the peak value of the rectified supply voltage. For at least this purpose, the peak value of the rectified supply voltage is determined and compared to that of the intermediate circuit voltage. If the intermediate circuit voltage is less than the peak value of the rectified supply voltage, the intermediate circuit voltage is increased to exceed the originally set setpoint value. This prevents free-wheeling diodes from becoming conductive at undesirable times and causing excessive currents.

Method and circuit arrangement for adapting the intermediate circuit voltage to the supply voltage

A circuit arrangement for generating representations of supply voltages that includes a first path that receives control signals, the first path having a subtracter for forming a difference signal from two of the control signals and a low pass filter to receive the difference signal. A second path receives the control signals, the second path includes a second low pass filters that passes frequencies higher than the first low pass filter does. Output signals of the first and second paths are fed to a combination network which, as a function of the difference between the output signals of the first and second paths, passes on the output signals of one of the first and second paths.

Method and circuit arrangement for generating a representation of the supply voltage in a frequency converter

An evaluation device with an absolute value counter is provided in an incremental position measuring system, which determines the absolute position even in case of loss of the main power supply. The evaluation device is operated by means of an emergency power supply while the main power supply is out. Following the restoration of the main power supply, counting pulses are supplied to a follow-up counter (11) by a pulse emitter, until the follow-up counter has reached the counter reading of the absolute value counter. Two rectangular signals, which are phase-shifted by 90.degree. in relation to each other, are formed as a function of the counting signals, which are present at the evaluation device in the form of output signals.

Incremental position measuring system

A measuring device is provided in which a graduated plate is scanned in at least two scanning locations. The scanning signals from the different scanning locations are transmitted to a testing circuit which determines whether the phase displacement between the scanning signals exceeds a limit value. If the limit value is exceeded, one of the scanning locations is weighted higher than the other. The weighting is implemented by increasing the components of the signals from one scanning location while decreasing the components from the signals from the other scanning location.

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Teisendorf, Germany

Norbert Huber