935 results about "Center tap" patented technology

Voltage regulators often have coupled output inductors because coupled output inductors provide improvements in cost and efficiency. Coupled inductors are often used in multi-phase voltage regulators. Feedback control of voltage regulators often requires accurate and responsive sensing of output current. Provided is a technique for accurately sensing the magnitude of output current in coupled inductors. An RC circuit (comprising a resistor and capacitor in series) is connected in parallel with the coupled inductor. The inductor has a leakage inductance Lk and a DC (ohmic) resistance of DCR. The resistor and capacitor are selected such that an RC time constant is equal to an L/R time constant of Lk/DCR. With the matching time constants, a sum of voltages on the capacitors is accurately proportional to a sum of currents flowing in the output inductors. Also provided is a technique for sensing current when an uncoupled center tap inductor is present.

A head for use in a drive includes a heating element capable of generating heat sufficient to cause the head to have a shape that is similar or identical to the shape that the head has when performing an operation (e.g. writing) on a recording medium in the drive. The heating element is activated when the operation is not being performed. Hence, a head generates the same amount (or similar amount) of heat and is therefore at the same temperature (also called “operating temperature”), regardless of whether or not an operation (such as writing) is being performed. Therefore, the head maintains a fixed shape or has a shape that varies minimally, within a predetermined range around the fixed shape, that in turn results in maintaining fly height (distance between the head and the recording medium). The heating element may be implemented to use loss mechanisms inherent in a write transducer, e.g. by providing a center tap to the write transducer. When using a center tapped write transducer, currents in phase with one another are provided to perform a write operation. When not performing the write operation, the same currents are provided, but out of phase.

The present invention discloses a forward-flyback converter with active-clamp circuit. The secondary side of the proposed converter is of center-tapped configuration to integrate a forward circuit and a flyback circuit. The flyback sub-circuit operating continuous conduction mode is employed to directly transfer the reset energy of the transformer to the output load. The forward sub-circuit operating discontinuous conduction mode can correspondingly adjust the duty ratio with the output load change. Under the heavy load condition, the mechanism of active-clamp flyback sub-circuit can provide sufficient resonant current to facilitate the parasitic capacitance of the switches to be discharged to zero. Under the light load condition, the time interval in which the resonant current turns from negative into positive is prolonged to ensure zero voltage switching function. Meanwhile, the flyback sub-circuit wherein the rectifier diode is reverse biased is inactive in order to further reduce the power losses.

A disk drive is disclosed comprising an interface for receiving a primary supply voltage and a secondary supply voltage from a host computer. The primary supply voltage is applied to the windings of a multi-phase spindle motor in a commutation sequence, and the secondary supply voltage is connectable to a center tap of the windings.

A step-down constant-current transformer including a controllable switch downstream from the one input and connected in series to a choke, a capacitor connected in parallel at the output, and upstream from the choke, a second controllable switch in parallel. Both controlled switches are MOSFET transistors. A control unit, in particular a pulse-width control unit, is provided for the MOSFET transistors. The voltage across the parallel-connected MOSFET transistor is monitored to determine whether a reverse current, i.e., a current flowing through the choke from the output in the direction of the input of the constant-current transformer, or an electric potential at the center tap of the half-bridge formed by the two MOSFET transistors is detected. For this purpose, a comparator and an AND circuit are provided, which, in the event of such a reverse current, block the parallel-connected MOSFET transistor to prevent the reverse current.

A power conversion circuit system comprises a primary conversion circuit, a secondary conversion circuit, and a control circuit for controlling the primary and secondary conversion circuits. The primary conversion circuit comprises a primary full bridge circuit, which includes a bridge section composed of both a primary coil in a transformer and a primary magnetic coupling reactor in which two reactors are magnetically coupled, a first input/output port disposed between a positive bus bar and a negative bus bar of the primary full bridge circuit, and a second input/output port disposed between the negative bus bar of the primary full bridge circuit and a center tap of the primary coil in the transformer. The secondary conversion circuit has a configuration similar to that of the primary conversion circuit.

A disk drive is disclosed comprising an interface for receiving a supply voltage from a host computer and control circuitry for controlling at least one operation of the disk drive. The supply voltage is applied to the windings of a multi-phase spindle motor in a commutation sequence during a normal operating mode, and a secondary voltage supplied by a center tap of the windings is used to power the control circuitry during the normal operating mode.

The invention relates to a resonant switched capacitor direct current voltage converter which comprises a first voltage node, a second voltage node, a first switch, a second switch, a first diode, a second diode and a control circuit, wherein a first voltage exists between the first voltage node and a negative wire; a second voltage exists between the second voltage node and the negative wire; and the control circuit provides switching gate signals for the first and the second switches. The resonant switched capacitor direct current voltage converter further comprises a center-tapped inductor and a resonant capacitor, wherein the center-tapped inductor is connected between the first switch and the second switch; and the resonant capacitor is connected between the common node of the first and the second diodes and the central node of the center-tapped inductor. Compared with the conventional switched capacitor direct current voltage converter, the invention has the advantages of reducing complexity, loss and cost, improving the speed, and avoiding the limitation.

A zero-voltage-switched, full-bridge, phase-shifted DC-DC converter for use in a DC power supply or battery charger includes a power transformer, four switching transistors connected to form a full bridge, and a decoupling capacitor and resonant inductor connected in series to the primary winding of the power transformer. At high loads, i.e., high output voltages, the resonant inductor charges the stray and internal capacitance of the switching transistors. Under light loads or in a no-load condition, with the current through the resonant inductor insufficient to allow the inductor to recharge these capacitances, the combination of a second inductor connected at one end to the central tap of the power transformer's primary winding and at its second opposed end to the middle point of a capacitive voltage divider, permits the second inductor to store enough energy to effectively recharge the stray and internal capacitance of the switching transistors for improved operating efficiency.

An integrated variable voltage diode capacitor topology applied to a circuit providing a variable voltage load for controlling variable capacitance. The topology includes a first pair of anti-series varactor diodes, wherein the diode power-law exponent n for the first pair of anti-series varactor diodes in the circuit is equal or greater than 0.5, and the first pair of anti-series varactor diodes have an unequal size ratio that is set to control third-order distortion. The topology also includes a center tap between the first pair anti-series varactor diodes for application of the variable voltage load. In preferred embodiments, a second pair of anti-series varactor diodes is arranged anti-parallel to the first pair of anti-series varactor diodes so the combination of the first pair of anti-series varactor diodes and the second pair of anti-series varactor diodes control second-order distortion as well.

A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.

The invention relates to equalizing equipment for battery units of an electric automobile, which comprises an inverse partial pressure battery unit equalizing system and a capacitor switching single equalizing system. In the inverse partial pressure battery unit equalizing system, two large capacitors which are connected in series are connected in parallel with a first switching tube MOSFET and asecond switching tube MOSFET which are connected in series to be crossed at two ends of the positive electrode and the negative electrode of a battery pack formed by connecting a plurality of batteryunits in series; the homonymous end of the primary side of a transformer is connected with the middle point of the large capacitors which are connected in series, and the heteronymous end of the transformer is connected with the source electrode of the first switching tube MOSFET; a multi-secondary side structure is adopted by the transformer; and the center tap of the secondary sides of the transformer is connected with the negative electrode of each battery unit. In the capacitor switching single equalizing system, four switching tubes MOSFET are connected in series in pairs; each series branch is respectively connected with the positive electrode and the negative electrode of two adjacent single batteries in each battery unit; and a filter capacitor is crossed with the middle point of the switching tubes MOSFET which are connected in series. The inverse partial pressure battery unit equalizing system equalizes a plurality of battery units which are connected in series, and the capacitor switching single equalizing system equalizes single battery in each battery unit.

Disclosed is a bi-directional battery power inverter (1) comprising a DC-DC converter circuit element (3) to which the battery (2) can be connected in order to generate an AC output voltage from a battery (2) voltage in a discharging mode while charging the battery (2) in a charging mode. The inverter (1) further comprises an HF transformer which forms a resonant circuit along with a resonant capacitor (6). In order to increase the efficiency of said battery power inverter, the transformer is provided with two windings (11,12) with a center tap (20) on the primary side, said center tap (20) being connected to a power electronic center-tap connection with semiconductor switches (21,31) while a winding (13) to which the resonant capacitor (6) is serially connected provided on the secondary side.

A neutral line regulator is designed as a plug-in module or new integrated inverter with a lower rating 4th-leg, instead of using a conventional four-leg inverter to supply power to three-phase four-wire unbalanced AC loads or three-phase nonlinear loads without a neutral connection. The neutral line regulator may be designed for controlling only the unbalanced power rather than using a fully rated inverter leg. Since this plug-in module may be separate from the main inverter and may operate at a lower power, the switching frequency may be higher than the main inverter. Thus, the size and weight requirements for providing the neutral line can be significantly reduced. In addition, the plug-in regulator may maintain voltage balance between the center-tapped DC link capacitors for non-linear, unbalanced loads. Moreover, the plug-in module may be used as a retrofit module replacing, for example, delta-wye transformers.

A family of switch-mode power supplies with low current stresses on switches and capable of producing an output voltage higher than the input voltage, incorporating a multiple-tap transformer driven by at least one ground-referenced switch. When the transformer is center-tapped, it is driven by two ground-referenced switches. The current stress in each switch is equal to the difference between the source current and the load current. The converters can operate in zero current switching and zero voltage switching. Integrated magnetics can be used to reduce further component count.