Dr. Johannes Heidenhain Gmbh

Johannes Heidenhain Gmbh

Dr. Johammes Heidenvain Gmbh

Franz Ritz

Norbert Huber

Walter Schmitt

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

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 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 for adjusting a switching threshold of a touch probe, which has a touch element that can be deflected out of a position of repose and which upon a deflection of the touch element out of its position of repose causes a defined change in a measurable system parameter and outputs a switching signal when the value of the system parameter exceeds the switching threshold. The circuit includes a device for measuring the measurable system parameter, an electrical circuit for ascertaining a reference value from which the switching threshold is determinable and an incremental corrector that changes the value of the measurable reference value to the value of the measurable system parameter at the position of repose of the touch element, in which the switching threshold is determinable from the reference value.

Method and circuit for adjusting a switching threshold of a touch probe

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

An apparatus is provided for inductive transfer of the scanning signal from a sensing head to a machine body. The apparatus includes cooperating inductive coupling elements between a receiving lug of the sensing head and the spindle of the machine. Cooperating coupling elements for inductive coupling are also provided between the spindle and the machine body. The coupling element of the receiving lug includes a coil with a ferromagnetic core. The spindle includes a second cooperating coil lying opposite to the receiving-lug coil which also includes a ferromagnetic core. The scanning signal is conducted from the detector to the coil in the receiving lug and is transferred inductively to the spindle. The scanning signal then passes over a transfer coil to a receiving coil. The transfer coil and receiving coil are configured such that the signal is transferred independently of rotation of the spindle relative to the machine body.

Apparatus for inductive signal transfer in sensing heads

An incremental length measuring instrument generates analog scanning signals S.sub.1, S.sub.2 with a certain period P which are applied to a comparator in conjunction with two reference signals R.sub.S1, R.sub.S2. The measuring instrument causes the scanning signals S.sub.1, S.sub.2 to change as a function of relative displacement to two components of the measuring instrument. The comparator generates an analog control signal S.sub.D as a function of the difference of the momentary values of the signals applied as inputs to the comparator. The analog control signal S.sub.D is applied as an input to a signal generator which includes an oscillator. The oscillator generates a number of pulses in dependence on the momentary value of the analog control signal S.sub.D. These pulses cause the reference signals R.sub.S1, R.sub.S2 to be modified by the signal generator. In addition, the pulses are fed in a direction dependent manner into an incremental counter which includes a numerical display. The counter maintains a count which is displayed as an indication of the relative position of the two components of the measuring instrument. The reference signals R.sub.S1, R.sub.S2 are modified by the pulses generated by the oscillator until their momentary values correspond to the momentary values of the scanning signals S.sub.1, S.sub.2. When this occurs, the difference between these momentary values is zero and the comparator no longer delivers the control signal S.sub.D, thereby causing the pulse generation by the oscillator to cease. When this happens, the displayed counter state on the incremental counter and the reference signals R.sub.S1, R.sub.S2 remain in their momentary states.

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Uebersee, Germany

Franz Ritz