Abstract:
Since parallel MOSFETs are usually driven with one gate signal in power applications, the current sharing between the MOSFETs is automatically established with regard to the characteristics of the individual MOSFETs. This may lead to a large non-uniformity of the current distribution between the MOSFETs. According to the present invention, an individual control of the on-resistances of the MOSFETs is provided, which allows for an improved current sharing between paralleled MOSFETs.
Abstract:
The invention relates to a circuit arrangement for a converter (1) with switches (S1, S2) for chopping a DC voltage U1 into a chopped DC voltage U3, comprising control means for controlling the switch-on times of the switches (S1, S2), in which switch-on times of the switches (S1, S2) alternate with each other and are separated from each other by dead-time phases Ttot, and circuit elements comprising a resonant circuit having at least one capacitor (Cr) and at least one coil (Lr) for converting the chopped DC voltage U3 into an output voltage U2. To ensure a reliable and interference-free ZVS operation of such a circuit, a circuit arrangement and a method of operating such a circuit arrangement are proposed in which a value for the energy/charge remaining in the resonant circuit for switching the switch in the inductive mode of operation is determined and compared with a threshold value by means of a comparator (24), and in which the switches (S1, S2) are controlled in dependence upon the comparison result.
Abstract:
The invention relates to an arrangement for converting mechanical energy into electrical energy comprising a piezoelectric auxiliary generator producing an auxiliary voltage and a main generator which is coupled mechanically with the auxiliary generator and producing the electrical energy.
Abstract:
The invention relates to a circuit arrangement for an MR apparatus, having a resonant circuit, which is formed by an MR receiving coil (L1) and a capacitor (C 1), and having an electronic control circuit (S) for switching the resonant circuit between two or more operating modes. The invention proposes that the electronic control circuit (S) be connected with a receiving device (L2) for wireless reception of a high-frequency electromagnetic control signal.
Abstract:
In the case of known switched-mode power supplies with integrated preconditioner, the control curves are largely congruent, but deviate from one another in low-load operation, whereby the unregulated intermediate circuit voltage increases. To improve efficiency in low-load operation, closed-loop control of the burst cycle is effected on the primary side of the voltage transformer. The intermediate circuit voltage (Uic) is limited to a permissible limit value (U limit). The closed-loop control device in the switching stage taps the intermediate circuit voltage at a voltage divider (R1, R2) which is arranged between the preconditioner functional unit (12) and the switching stage (13). An assembly additionally monitors the output voltage, for example by means of an optocoupler (17). Burst mode comprises one or more burst cycles. A burst cycle is started when the intermediate circuit voltage (Uic) reaches its limit value (U limit). At this time, the voltage transformer is switched off. A burst cycle ends when the output voltage (U0) reaches a minimum value (U min). At this time (t3) at the latest, the voltage transformer (7) is switched on again. Burst mode is terminated again either when the switched-mode power supply is again operated under normal load or when a maximum time has elapsed, measured from the start of burst mode.
Abstract:
Die vorliegende Erfindung bezieht sich auf eine Schaltung für ein System zur kontaktlosen, induktiven Energieübertragung, insbesondere zur Anwendung bei der Energieversorgung mobiler Geräte sowie auf eine zugehörige Ladeschaltung. Die Schaltung umfasst eine primarseitige Schaltung, die auf einer Primärseite angeordnet und mit einer primärseitigen Versorgungsspannung verbindbar ist, und eine sekundärseitige Schaltung, die auf einer Sekundärseite angeordnet und mit einer mit Energie zu versorgenden Last verbindbar ist. Weiterhin ist eine Übertragerstufe mit galvanischer Trennung zum kontaktlosen Übertragen von Energie von der Primärseite über einen Luftspalt hinweg auf die Sekundärseite vorgesehen, wobei mindestens zwei magnetisch gekoppelte Spulen zur induktiven Energieübertragung vorgesehen sind, die durch Entfernen der Sekundärseite von der Primärseite räumlich voneinander trennbar sind. Die Übertragerstufe weist einen resonanten Wandler auf und die sekundärseitige Schaltung weiterhin eine Nachstabilisierungsstufe umfasst.
Abstract:
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 (18) is provided for converting an audio signal to a power output, comprising a ripple suppression circuit (16) for suppressing voltage ripples in a supply voltage supplied to the bridge circuit with (6) at least one pair of switches. The ripple suppression circuit (16) suppresses ripples in the supply voltage supplied to a switch in the bridge circuit (6), which has been found to cause a major part of the distortions in the output signal of the digital amplifier (18).
Abstract:
An electronic packaging structure, comprising a substrate; a first electrode layer on a first side of said substrate; dielectric material arranged in a preselected pattern on said first electrode layer); and a second electrode layer forming a plurality of second electrodes which are arranged on said preselected pattern of dielectric material to form a distributed capacitive structure together with said first electrode layer, is characterized in that a second decoupling capacitor stage is arranged on a second side of said substrate opposite said first side and is electrically connected to said distributed capacitive structure, said second decoupling stage having a capacity higher than that of said distributed capacitive structure.
Abstract:
The invention relates to a power converter comprising an inductor 6 for receiving energy from a power supply 1, and connected to the inductor 6 an output capacitor 7 for providing an output voltage. In order to ensure a quick compensation of a reduction of load at the voltage output using few output capacitors, it is proposed that an additional current path 11,12 is arranged in parallel either to the inductor 6 or to the capacitor 7, which additional current path 11,12 can be opened and closed. A current flowing through the additional current path 11,12 reaches basically immediately a desired value, when the additional current path 11,12 is opened. Feedback means are moreover provided for opening the additional current path 11,12, when the output voltage reaches a predetermined maximum value. The invention relates equally to a corresponding method.
Abstract:
A method for controlling the transient response of a power converter powering a load, said power converter comprising a power switch, a synchronous rectifier and a capacitor coupled between an input and an output of the power converter, said method comprising the step of-disabling said synchronous rectifier in response to a signal indicative of a change of said load, is characterized by-providing said signal based on a current representing said change of load.