U.S. Philips Corporation

Koninklijke Philips Corporation N.v.

Nxp B.v.

U.S. Phillips Corporation

Whirlpool International B.v.

Heinz Willi Van Der Broeck

Matthias Wendt

Bernhard Wagner

Christoph Loef

Martin Wimmer

Arne Lunding

Dirk Hente

Thomas Duerbaum

Peter Luerkens

Joseph Hendrik Anna Maria Jacobs

Georg Sauerländer

Thomas Dürbaum

Hans Negle

Hans Steinbusch

Ralf Austermann

Wolfgang Rexhausen

Enrico Vasconi

Diethard A Peter

Iain Mosely

F Javier Esguevillas

Heiko Osterholz

Reinhard V Hacht

Norbert Geerkens

Horticultural lighting system comprising a first string () of at least one light element (), a second string () of at least one light element (), both strings being electrically connected in parallel with each other, a power supply unit () providing an AC current/voltage to the parallel circuit of the strings, and means for energizing () the first string during a first half period of the AC voltage and the second string during a second half period of the AC voltage, so that each string radiates pulsed light, said first string and said second string being arranged such that different areas () are irradiated. The lighting system is also to be used in an environment where living organisms are irradiated with light, or a greenhouse for exposing plants to pulsed light. A corresponding method is also claimed.

Lighting system for horticultural applications

Supply circuits (---) for supplying output current signals to loads () and comprising first circuits () with transistors (---) for converting input voltage signals into pulse signals and comprising second circuits () with resonance circuits for receiving the pulse signals and for supplying the output current signals to the loads () are provided with third circuits () for controlling the first circuits (), which third circuits () comprise generators (-) for generating control signals for controlling the transistors (---) for reducing dependencies between the input voltage signals and the output current signals. The third circuits () supply the control signals in dependence of the input voltage signals and independently from the output current signals. The transistors (---) may form a full bridge, a full bridge operated in a half bridge mode, or a half bridge.

Supply circuit and device comprising a supply circuit

Recently, the use of class-D audio amplifiers has become more and more widespread. In contrast to the generally employed class-AB linear amplification technology, class-D allows for improved efficiency. However, the class-D principle is known for its poor distortion characteristics. According to the present invention a digital amplifier () is provided for converting an audio signal to a power output, comprising a ripple suppression circuit () for suppressing voltage ripples in a supply voltage supplied to the bridge circuit with () at least one pair of switches. The ripple suppression circuit () suppresses ripples in the supply voltage supplied to a switch in the bridge circuit (), which has been found to cause a major part of the distortions in the output signal of the digital amplifier ().

Digital amplifier

A conversion circuit for converting solar power into an alternating 3-phase mains comprises a converter for converting the power from a solar cell into an unipolar converter output voltage provided between a first and a second converter output terminal of the converter, the converter having a constant power output regulation. The conversion circuit further comprises an inverter for cyclically switching one of three 3-phase output terminals to the first converter output terminal, one to the second converter output terminal and one intermittently to the first and second converter output terminal. With this conversion circuit and method, high capacity energy storage components (such as a capacitor having a large capacitance) can be avoided in the conversion circuit.

3-phase solar converter circuit and method

A circuit arrangement for commutating the AC voltage of a plasma display panel, in which the losses and electro-magnetic interference which occur as a result of the influence of parasitic resistances (coils, supply lines, semiconductor switches) and the attendant hard charging and discharging processes, are substantially avoided. For the charging operation of the capacitor (Cp) of the plasma cells the oscillation circuit is supplied with an auxiliary charging voltage (u) whose value exceeds 50% of the input voltage (U). The oscillation circuit for the discharging operation is supplied with an auxiliary discharging voltage (u) whose value falls short of 50% of the input voltage (U). The two auxiliary voltages are connected to a DC converter.

Circuit arrangement for the AC power supply of a plasma display panel

A method of controlling a circuit arrangement for an AC voltage supply of a plasma display panel, the circuit arrangement comprising at least a transistor bridge constituted by the bridge transistors (T, T, T, T), an input voltage (U), a capacitor (Cp) of the plasma cell and a charging circuit comprising an auxiliary voltage (Uh), a first auxiliary transistor (T) and a first coil (L) and at the beginning of the charging operation the first auxiliary transistor (T) is turned on, characterized in that once the first auxiliary transistor (T) has been turned on, the second bridge transistor (T) of the half bridge continues to be turned on for a delay time tv and is turned off after the delay time tv has elapsed.

Method of controlling a circuit arrangement for the ac power supply of a plasma display panel

A power supply for X-ray generators which includes at least one inverter (), at least one transformer () and at least one voltage cascade () for generating a supply voltage for an X-ray tube (). In order to increase the output power that can be achieved with a comparatively small weight and a low ripple or output capacitance, the voltage cascade is conceived in respect of its capacitances and the stray inductance of the transformers () in such a manner that it can be made to operate in the resonance mode by appropriate control of the inverter. In respect of the properties mentioned it is notably advantageous to integrate a two-phase embodiment or three-phase embodiment with an X-ray system so as to form a compact tank generator.

Power supply for an X-ray generator

In an X-ray device which includes an X-ray tube (12) provided with means (15, 22, 23) for influencing the electron flow through the X-ray tube (12), a control voltage for the means for influencing the electron flow is customarily generated by means of a complex circuit which, because of its size, is not suitable to be accommodated within the protective tube housing. This has the drawback that the control voltage for the X-ray tube, usually of high voltage potential, must be supplied additionally to the high-voltage supply. Therefore, it is desirable to realize a simple generation means the control voltage which is suitable for accommodation in the protective tube housing. To this end, the invention proposes a piezoelectric transformer (21, 24, 25) for generating the control voltage for the X-ray tube. The invention also relates to a piezoelectric transformer which is particularly suitable for generating such a control voltage.

X-ray device including a piezoelectric transformer

The invention relates to a power supply unit which includes an inverter having output connections whereto the primary winding of a transformer is connected via a series capacitor. The rectified secondary voltage of this transformer is applied to a use which requires a high short-time power in a first mode of operation and a lower continuous power in a second mode of operation. The maximum permissible continuous power can be increased by means of an auxiliary inductance Lh which is active in the second mode of operation but inactive in the first mode of operation.

Power supply unit including a pulse width modulated inverter, notably

A circuit arrangement for powering a load having n terminals includes n branches. One of the terminals of the load is switchably connected to a first or a second terminal of a voltage source by each of the branches resulting in a voltage vector having n components being applied to the load. The vector components can each assume two values based on the voltage of the voltage source. A control circuit sets the n components of the voltage vector to one of the two values. When all n components assume the same value within some portion of a given period of time (referred to as null vector) and provided that at least one of the components of the voltage vector during this given period of time reamins at this same value, the control circuit sets all components of the voltage vector to the other value so as to form a second null vector. The circuit arrangement prevents a voltage on a terminal of the load from being sustained at a given voltage beyond a given period of time without corrective action being taken.

Circuit arrangement for powering a load

A power supply circuit for a two-phase asynchronous motor having two windings at a preset angle there-between. The supply circuit has three nodes at which are respectively supplied three node voltages U1, U2, U3 which are derived as logic combinations of a basic pulse train and a pulsed switching signal having a switching frequency and a duty cycle. The motor windings are respectively connected between the first and second nodes and between the second and third nodes. The voltage U2 at the second node has a rectangular waveform. The voltages U1 and U3 at the first and third nodes alternate between time intervals in which the voltage level is constant and time intervals in which the voltage is pulse modulated, and have a phase angle there-between corresponding to that between the motor windings. Pulse modulated intervals of each of the first and third node voltages coincide with constant voltage intervals of the other of those voltages, and the pulses in the pulse modulated intervals have a duty cycle which corresponds with a desired amplitude ratio of the voltages produced across the motor windings. The circuit achieves significant reduction in the required number of switching edges of the node voltages, thereby reducing power dissipation.

Circuit arrangement for powering a two-phase asynchronous motor

An X-ray apparatus, includes a power supply section for powering an X-ray tube (4) with a high-voltage transformer (3) which has two groups of primary and secondary windings provided on the same transformer core, the coupling between the primary windings (16, 26) belonging to different groups being weaker than the coupling between primary and secondary windings (for example, 16, 31) belonging to the same group, the primary windings of the two groups being connected to two inverters (1, 2) which operate at the same frequency. Control of the power at the secondary side is improved in that the inverters are operated at a fixed frequency and with a duty cycle which can be independently controlled.

X-ray apparatus comprising a power supply section for powering an X-ray

A circuit arrangement comprises an inverter with two parallel switching branches which are connected to a DC voltage source and each of which comprises two series-connected switching members, each of which comprises at least one switch and an anti-parallel connected diode. A switching member in one switching branch each time constitutes a diagonal pair in conjunction with a switching member in the other switching branch. A load with a given polarity is connectable to a DC voltage source via the diagonal pair. The voltage on the load temporarily becomes zero upon the change-over from one polarity to the other. A control circuit is provided for opening and closing the switches in a manner such that the switching members are successively switched on and off. The switching members are more uniformly stressed because the control circuit is constructed so that all of the switching members are successively switched on as the second switching member in their diagonal pair or all of the switching members are successively switched off as the second switching member in their diagonal pair.

DC/AC converter with equally loaded switches

A circuit arrangement for powering a two-phase asynchronous motor having two windings which each have one end connected to one anode and both have another end connected to a third node, the nodes each being arranged to receive one of three alternating voltages whose sinusoidal fundamental waves at least substantially correspond in frequency. In this circuit arrangement, the power dissipation in the switching circuit connected to the third node is reduced by the alternating voltage applied to the third node having constant levels in periodically recurring time intervals so as to obtain a more economical dimensioning without a deterioration of the operating characteristics, particularly the loadability.

A circuit arrangement for commutating a reluctance motor including a current generator which produces first and second cyclic sequences of current pulses. In response to the first cyclic sequence applied to the stator windings of the motor, a rotor travels a predetermined distance along a motion coordinate path. Application of the second sequence to the stator windings results in the rotor traveling at least twice the predetermined distance along the motion coordinate path. The second sequence, which is applied when rotor speed exceeds a predetermined level, is formed by omitting predetermined current pulses from the first cyclic sequence.

Growing community of inventors

Zuelpich, Germany

Heinz Willi Van Der Broeck