Abstract: A bidirectional power converter includes flyback converter units connected in parallel, each having a controller and adapted to accumulate power from a primary side during an ON time and to deliver the accumulated power to a secondary side during an OFF time, the primary and secondary sides being interchangeable as to the direction of power conversion, the controller operating at a boundary between discontinuous and continuous conduction modes and performing valley switching when switching from OFF to ON, one converter unit operating as a master wherein the controller is adapted to control the length of ON time in order to feedback-control an overall current output of the converter, and each other converter unit operating as a slave wherein the controller controls the length of ON time in order to feedback-control a phase delay of ON time of the slave relative to ON time of another converter unit.

Abstract: A driver (1) for driving a gas discharge lamp (2) comprises:—a current source (3) generating lamp current, having a setpoint input (4) for receiving a setpoint signal;—a controller (10) generating a current setpoint signal (SM);—a controllable noise signal source (20) generating a pseudo random noise signal (SPRNS);—an adder (22) adding the current setpoint signal (SM) from the controller and the pseudo random noise signal (SPRNS) from the noise signal source, and providing the result to the setpoint input of the current source;—measuring means (40) measuring a characteristic lamp response of the lamp in response to the pseudo random noise signal (SPRNS), and providing to the controller a sense signal;—a memory (30) associated with the controller, having stored therein at least one reference signal. The controller compares the measured lamp response with said predetermined reference signal in the memory, and may switch off the lamp.

Abstract: A lamp driver circuit for operating a gas discharge lamp (La) is proposed, which comprises a switched mode power supply circuit (SMPS) and a first and a second output terminal (OT1, 0T2) for supplying a lamp current to the gas discharge lamp (La). The lamp driver circuit further comprises an output capacitor (CO) connected between the SMPS circuit and a ground terminal (GT) and comprises a resistive shunt (Rsh) connected between the ground terminal (GT) and the second output terminal (0T2) for determining the lamp current. An output current sensing circuit for determining a SMPS output current is comprised in the lamp driver circuit instead of a further resistive shunt, which would require a differential voltage measurement. The output current sensing circuit comprises a sensing resistor (RS) connected in series with a sensing capacitor (CS), the series connection being connected in parallel to the output capacitor.

Abstract: A circuit arrangement and a method for operating a high intensity discharge lamp driver, which assure long-lasting stable operation of a high intensity discharge lamp regardless of the type or the age of the lamp. This is achieved by the determination of a correctional setpoint signal for a given time period based on the a difference signal between a principal setpoint signal and the actual output current signal for a given time period. The principal setpoint signal is then adjusted by the determined correctional setpoint signal.

Abstract: A lamp driver circuit for operating a gas discharge lamp (La) is proposed, which comprises a switched mode power cc supply circuit (SMPS) and a first and a second output terminal (OT1, 0T2) for supplying a lamp current to the gas discharge lamp (La). The lamp driver circuit further comprises an output capacitor (CO) connected between the SMPS circuit and a ground terminal (GT) and comprises a resistive shunt (Rsh) connected between the ground terminal (GT) and the second output terminal (0T2) for determining the lamp current. An output current sensing circuit for determining a SMPS output current is comprised in the lamp driver circuit instead of a further resistive shunt, which would require a differential voltage measurement. The output current sensing circuit comprises a sensing resistor (RS) connected in series with a sensing capacitor (CS), the series connection being connected in parallel to the output capacitor.

Abstract: In a method and circuit for operating a gas discharge lamp, the physical processes occurring in the gas discharge lamp are determined in order to control the behavior, and thus the light output, of the gas discharge lamp. Thereto, the method comprises the steps of, and the circuit comprises means for, providing an operating current to the gas discharge lamp and determining an operating parameter of the gas discharge lamp. Based on the determined operating parameter a value of a physical lamp parameter of the gas discharge lamp is determined. Using the determined value of the physical lamp parameter and a corresponding mathematical model of a physical process occurring in the gas discharge lamp an operating state of the gas discharge lamp is estimated. Using the model, which is based on the physical principles of the processes occurring in the gas discharge lamp, it is possible to determine the physical state of the gas discharge lamp.

Abstract: A driver (1) for driving a gas discharge lamp (2) comprises: -a current source (3) generating lamp current, having a setpoint input (4) for receiving a setpoint signal; -a controller (10) generating a current setpoint signal (SM); -a controllable noise signal source (20) generating a pseudo random noise signal (SPRNS); -an adder (22) adding the current setpoint signal (SM) from the controller and the pseudo random noise signal (SPRNS) from the noise signal source, and providing the result to the setpoint input of the current source; -measuring means (40) measuring a characteristic lamp response of the lamp in response to the pseudo random noise signal (SPRNS), and providing to the controller a sense signal; -a memory (30) associated with the controller, having stored therein at least one reference signal. The controller compares the measured lamp response with said predetermined reference signal in the memory, and may switch off the lamp.

Abstract: Current arrangement for operating a high intensity discharge lamp or a ultra high pressure discharge lamp, comprising a DC-to-DC converter, a control circuit for controlling the output value of the DC-to-DC converter, and a commutator. The control circuit comprises two control loops, one of which controlling an absolute average value of the lamp current, the other of which controlling and minimizing small variations of the lamp current around a reference value. An adaptive control of the first and second loop controllers can be used to adjust the controllers to changing system dynamics.

Abstract: A circuit arrangement for operating a high pressure discharge lamp comprises a down converter equipped with an output capacitor and a commutator equipped with lamp connection terminals. The amplitude of the DC current generated by the down converter is controlled by means of a control loop. Commutation of the DC current causes a periodical voltage to be present across the output capacitor. This periodical voltage can be an overshoot voltage and/or a voltage caused by resonance of the lamp with the output capacitor. To suppress the periodical voltage, the reference signal of the current control loop is adjusted in dependency of the amplitude of the periodical voltage.

Abstract: A circuit for a discharge lamp includes a first sub-circuit for connecting to mains voltage of a predetermined frequency for rectifying the mains voltage; and a second sub-circuit connected to the first sub-circuit for providing an alternating current, such as a square-wave current, required for the lamp. A control circuit is connected to the first and the second sub-circuit. The control circuit controls the frequency of the alternating current subject to a varying component of the mains voltage rectified by the first sub-circuit.

Abstract: Circuit for driving a load, comprising: two input terminals for connection to a source of a supply voltage; a first and a second output terminal for connection to the load; at least one inductor coupled between one of the output terminals and a corresponding connection node; at least one arrangement comprising a switch coupled between one of said input terminals and one of said connection nodes, a diode being connected between said one connection node and the other input terminal; a control unit for controlling said one or more switches; wherein each arrangement and corresponding diode are designed to allow the voltage over the opened switch of said arrangement to return to substantially zero before said switch is closed, the control unit being designed to provide a signal for closing the switch when a substantially zero voltage over said opened switch is detected. Turning the switch on at a substantially zero voltage means that switching losses are greatly reduced, and this without complicating the circuit.

Abstract: A circuit arrangement and a method for operating a high intensity discharge lamp driver, which assure long-lasting stable operation of a high intensity discharge lamp regardless of the type or the age of the lamp. This is achieved by the determination of a correctional setpoint signal for a given time period based on the a difference signal between a principal setpoint signal and the actual output current signal for a given time period. The principal setpoint signal is then adjusted by the determined correctional setpoint signal.

Abstract: An DC/AC converter for supplying two gas discharge lamps, includes a double bridge configuration of four switches and a controller. The controller controls the conducting periods of the switches with a duty cycle which is variable. By control of the conducting periods of the switches, a proper control of the energy supplied to the lamps is obtained.

Abstract: The invention relates to a device for operating a high-pressure discharge lamp, comprising: a switched-mode power supply circuit for supplying power to the high-pressure discharge lamp from a supply voltage, the power supply circuit comprising at least one power switching element, and control means for controlling the at least one power switching element in its switched-on and switched-off states for controlling the power or current supplied to the high-pressure discharge lamp. According to the invention the control means are adapted to control the power consumed by the lamp during its steady phase or the current consumed by the lamp during its run-up phase by controlling the on-time (Ton) of the switched-on state of the at least one power switching element.

Abstract: Driver (150) for a gas discharge lamp (9) comprises: an arrangement of two MOSFET switches (61, 62) connected in series between two input terminals (51a, 52b); an inductor (73) connected in series with said lamp (9), this series arrangement being coupled to a node (P) between said two switches; a control unit (180) providing control signals (S1, S2) to said two switches. During a first commutation interval (41), a lamp circuit current (ILC) has only a first direction while during a second commutation interval (42) said lamp circuit current has only an opposite direction. In each commutation interval (41, 42), during a first operational phase (43) said lamp circuit current has a continuously increasing level while during a second operational phase (44) said lamp circuit current has a continuously decreasing level. The control unit (180) is designed to generate its control signals (S1, S2) such that said two switches are always, switched substantially simultaneously in counter-phase.

Abstract: In a bridge circuit for operating a high pressure discharge lamp an additional switching element, a control circuit for driving the additional switching element, a resonant inductor and a resonant capacitor are incorporated. The additional components together form a comparatively simple resonant igniter. The resonant inductor can be formed by part of a filter comprised in the bridge.

Abstract: A DC-AC converter in a half bridge configuration is used for operation with high pressure discharge lamps as well as low pressure discharge lamps. The converter consists in two switches (T1-T2) serially connected through a first series of diodes (D1, D2) and a second series of diodes (D3,D4) to which at their middle points (N1, N2) a first and a second lamp loads (L1,L2,LA1,LA2) are connected. Furthermore, the second terminals of the lamp loads are connected to the middle point of a series of capacitors (C3,C4) which are also connected to the terminals (Ki,K2) of the supply voltage source. The converter includes also four diodes (D5,D6,D7,D8) which shunt the switches (T1,T2) and their respective series of diodes (D1,D2,D3,D4). The switches (T1,T2) are controlled by a controller (CC) which renders alternatively conductive at low frequency the two switches (Ti,T2).

Abstract: In a ballast circuit for supplying a high pressure discharge lamp and comprising an up-converter and a bridge circuit, the output voltage of the up-converter is controlled at a higher level immediately after the ignition of the lamp and at a lower level during stationary operation. Stabilization of the discharge immediately after ignition of the lamp and a relatively small power dissipation are both realized in this ballast circuit.

Abstract: A switch mode power supply for igniting and operating a high-pressure gas discharge lamp includes an ignition sub-circuit which is coupled via a transformer to the circuit. The ignition sub-circuit has at least an ignition capacitor, and a switching element for discharging the capacitor at a desired moment in time having a control electrode. The control electrode of the switching element is connected to the commutator of the lamp circuit via a control sub-circuit having substantially passive elements.

Abstract: The present invention relates to an Electronic ballast for operating a high-pressure discharge lamp, comprising a switched-mode power supply circuit (SMPS) for supplying a rail voltage Vrail to the high pressure discharge lamp, the power supply circuit comprising a half bridge commutating forward circuit including an inductance (Lhbcf), a capacitor circuit of a first capacitor (Cs1) and a second capacitor (Cs2) in series, the lamp (LA) being connectable between the inductance (Lhbcf) and a midpoint (M) between the first and second capacitor (Cs1,Cs2); a duty cycle control circuit, connected to the switched-mode power supply circuit, for controlling the duty cycle of the half bridge commutating forward circuit; and overvoltage protection means for protecting said capacitors against overvoltage, comprising—a midpoint voltage detection circuit for detecting the voltage at the midpoint between the first and second capacitor, the midpoint voltage detection circuit providing a first signal representative of the det