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28 条记录 (耗时 0.023 秒)

    Split gradient amplifier for an MRI system
    1.
    发明授权
    Split gradient amplifier for an MRI system 失效
    用于MRI系统的分离梯度放大器

    公开(公告)号：US5270657A

    公开(公告)日：1993-12-14

    申请号：US965131

    申请日：1992-10-22

    申请人： William F. Wirth ,  Thomas G. McFarland ,  Robert M. Vavrek ,  Peter B. Roemer ,  Otward M. Mueller ,  John N. Park

    发明人： William F. Wirth ,  Thomas G. McFarland ,  Robert M. Vavrek ,  Peter B. Roemer ,  Otward M. Mueller ,  John N. Park

    IPC分类号： G01R33/385 ,  G01V3/00

    CPC分类号： G01R33/3852

    摘要： A gradient amplifier for use in magnetic resonance imaging equipment employs a low voltage DC power supply connected in series between a pair of higher voltage DC power supplies, the latter supplies serving to provide increased power for rapid gradient switching and the former supply providing correction current to produce the desired voltage output. The high voltage DC power supplies preferably comprise multiple DC units which can be combined to provide finer steps of control prior to correction by the lower voltage supply. The low voltage DC power supply preferably comprise one or more linear amplifiers connected in series, or one or more switchmode amplifiers connected in series. The DC power supplies are controlled in an open loop manner from a gradient signal that designates the desired current for the gradient coil and the amplifiers are operated in a closed loop responding to to a feedback signal from the gradient coil.

    摘要翻译： 用于磁共振成像设备的梯度放大器采用串联连接在一对高压直流电源之间的低压直流电源，后者用于为快速梯度切换提供增加的功率，而前一个电源提供校正电流 产生所需的电压输出。 高压DC电源优选地包括多个DC单元，其可以组合以在由较低电压源进行校正之前提供更精细的控制步骤。 低压DC电源优选地包括串联连接的一个或多个线性放大器或串联连接的一个或多个开关模式放大器。 直流电源由开路环路控制，该梯度信号指定用于梯度线圈的期望电流，并且放大器响应于来自梯度线圈的反馈信号在闭环中工作。

    Transformer-coupled gradient speed-up circuit
    2.
    发明授权
    Transformer-coupled gradient speed-up circuit 失效
    变压器耦合梯度速度电路

    公开(公告)号：US5063349A

    公开(公告)日：1991-11-05

    申请号：US533233

    申请日：1990-06-04

    申请人： Peter B. Roemer ,  Otward M. Mueller ,  John N. Park ,  William McMurray

    发明人： Peter B. Roemer ,  Otward M. Mueller ,  John N. Park ,  William McMurray

    IPC分类号： A61B5/055 ,  G01R33/385 ,  G01R33/48 ,  H01F7/20

    CPC分类号： G01R33/3852

    摘要： A gradient current speed-up circuit, for use in a higher-speed NMR imaging system having an associated gradient coil, has a gradient power amplifier receiving an input analog signal controlling amplifier output current, and a transformer having a primary winding and a pair of secondary windings connected in series with the amplifier output and the coil. Semiconductor switching elements selectively connect the primary winding between first and second potential sources, and are turned on and off in selected patterns to cause a current to be suddenly applied to, and removed from, flow through the associated gradient coil; the amplifier output current is changed with the gradient coil current lags behind an amplitude commanded by a master input signal.

    Snubbers for low temperature power electronics
    4.
    发明授权
    Snubbers for low temperature power electronics 有权
    低温功率电子缓冲器

    公开(公告)号：US07369377B1

    公开(公告)日：2008-05-06

    申请号：US11224184

    申请日：2005-09-12

    申请人： Michael J. Hennessy ,  John N. Park ,  Otward M. Mueller ,  Eduard K. Mueller

    发明人： Michael J. Hennessy ,  John N. Park ,  Otward M. Mueller ,  Eduard K. Mueller

    IPC分类号： H02H7/00 ,  H02H9/00 ,  H01L29/00 ,  H01L23/34

    CPC分类号： H03K17/92 ,  H01L2924/0002 ,  H01L2924/00

    摘要： Switching losses and conduction losses are isolated by networks which are partially cryogenic and partially at room temperature. Switching losses are independent of temperature. Advantageously the switching losses are taken in a snubber network at room temperature and conduction losses are incurred at cryogenic temperatures, where majority carrier devices like MOSFETs operate with ultra low on-state resistance and corresponding low conduction losses. Low loss leads carry current efficiently from the cryogenic environment to room temperature without adversely affecting refrigeration. Switch and snubber network may both operate cryogenically.

    摘要翻译： 开关损耗和传导损耗由部分低温部分在室温的网络隔离。 开关损耗与温度无关。 有利地，开关损耗在室温下在缓冲网络中进行，并且在低温下产生传导损耗，其中诸如MOSFET的多数载流子器件以超低导通状态电阻和相应的低导通损耗工作。 低损耗引线可将电流从低温环境有效地运送到室温，而不会对制冷产生不利影响。 开关和缓冲网络都可以低温运行。

    Ring configuration for compact power supply of power electronics
    5.
    发明授权
    Ring configuration for compact power supply of power electronics 有权
    电源电子紧凑型电源的环形配置

    公开(公告)号：US07619325B1

    公开(公告)日：2009-11-17

    申请号：US11224183

    申请日：2005-09-12

    申请人： Michael J. Hennessy ,  Otward M. Mueller ,  Eduard K. Mueller ,  John N. Park

    发明人： Michael J. Hennessy ,  Otward M. Mueller ,  Eduard K. Mueller ,  John N. Park

    IPC分类号： H01B7/30

    CPC分类号： H02M3/00 ,  H02M7/003

    摘要： An ultra compact ring topology puts the output terminals of solid state switches physically at the center of a circuit with the switches surrounded by voltage busses. The switches are symmetrically arranged around the output bus, the voltage busses are filtered (decoupled) to ground using symmetrically positioned filter components, and lead lengths to and from the switches are minimized. Switch driver circuits are closely integrated with each switch and positioned as close as possible, each to its associated switch, and arranged symmetrically. Switches may be at cryogenic temperatures and busses and lead connectors may be superconductive.

    摘要翻译： 超紧凑的环形拓扑将固态开关的输出端子物理地置于电路中心，开关由电压总线包围。 这些开关对称地布置在输出总线周围，电压总线通过对称定位的滤波器组件被过滤（去耦合）到地，并且使来自开关的引线长度最小化。 开关驱动器电路与每个开关紧密集成，并且尽可能靠近并定位于其相关联的开关上，并对称地布置。 开关可能处于低温，母线和引线连接器可能是超导的。

    Resonant inverter with improved control
    6.
    发明授权
    Resonant inverter with improved control 失效
    谐振逆变器具有改进的控制

    公开(公告)号：US4672528A

    公开(公告)日：1987-06-09

    申请号：US866818

    申请日：1986-05-27

    申请人： John N. Park ,  Robert L. Steigerwald

    发明人： John N. Park ,  Robert L. Steigerwald

    IPC分类号： H02M3/337 ,  H02P13/20

    CPC分类号： H02M3/3376 ,  H02M2007/53878 ,  Y02B70/1433 ,  Y02B70/1441

    摘要： A resonant inverter is operated in a manner to provide a substantially constant output voltage to a load. The inverter is controlled using either a frequency control mode or a phase shift control mode. In the frequency control mode, a constant output voltage is maintained through frequency variation of the rectangular wave signal applied to the resonant circuit of the inverter. In the phase shift control mode, constant output voltage is maintained by phase shifting one component signal of the rectangular wave signal relative to another component signal thereof while maintaining constant the frequency of both component signals. Mode switching occurs automatically at the extremities of the operating frequency range of controllable switch means in the resonant inverter.

    摘要翻译： 谐振逆变器以向负载提供基本恒定的输出电压的方式操作。 使用频率控制模式或相移控制模式控制变频器。 在频率控制模式中，通过施加到逆变器的谐振电路的矩形波信号的频率变化来保持恒定的输出电压。 在相移控制模式中，通过相对于其另一分量信号相移矩形波信号的一个分量信号并保持两个分量信号的频率恒定来维持恒定的输出电压。 在谐振逆变器的可控开关装置的工作频率范围的末端，自动切换模式。

    FET Motor drive system
    7.
    发明授权
    FET Motor drive system 失效
    FET电机驱动系统

    公开(公告)号：US4347464A

    公开(公告)日：1982-08-31

    申请号：US239724

    申请日：1981-03-02

    申请人： John N. Park ,  Robert L. Steigerwald

    发明人： John N. Park ,  Robert L. Steigerwald

    IPC分类号： H02K29/08

    CPC分类号： H02K29/08

    摘要： A multipole permanent magnet rotor is positioned on a shaft and rotatably mounted in a multiphase stator having two windings per stator phase. A distributor comprising a pattern of conducting and non-conducting material is mounted to turn with the rotor shaft. Pickup "fingers" in contact with the distributor, gate appropriate FET's of the pairs of FET's associated with each stator phase in sequence, with timing dependent on the instantaneous shaft position, to generate a rotating flux field. A voltage across the windings provides the current for flux generation, and can be supplied by a full wave rectified single phase AC source. The speed of rotation of the motor can be controlled by varying the voltage supplied.

    摘要翻译： 多极永磁转子位于轴上并可旋转地安装在每个定子相中具有两个绕组的多相定子中。 包括导电材料和非导电材料的图案的分配器安装成与转子轴一起转动。 拾取“指”与分配器接触，按顺序选择与每个定子相位相关联的FET对，其中定时取决于瞬时轴位置，以产生旋转磁通场。 绕组两端的电压提供了用于产生磁通的电流，并且可以由全波整流的单相交流电源提供。 可以通过改变所提供的电压来控制电动机的旋转速度。