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    ACTIVE EMI FILTER WITH FEED FORWARD CANCELLATION
    23.
    发明专利
    ACTIVE EMI FILTER WITH FEED FORWARD CANCELLATION 未知

    公开(公告)号：AU2003202223A1

    公开(公告)日：2003-07-24

    申请号：AU2003202223

    申请日：2003-01-03

    Applicant: INT RECTIFIER CORP

    Inventor： TAKAHASHI TOSHIO ,  HONDA JUN ,  PELLY BRIAN

    IPC: H03H11/04 ,  H02M1/12 ,  H02M1/15 ,  H02M1/44 ,  H02M5/458

    Abstract: An active EMI filter for reducing common mode current in a circuit comprising a rectifier coupled to an AC network, the rectifier supplying DC power to a DC bus, the DC bus feeding an inverter stage for providing AC power to a load, the load having a ground return line to a ground connection of the AC network, the active filter comprising: a transistor switching stage coupled across the DC bus, a current sensor coupled to the DC bus for sensing the common mode current flowing in the DC bus and proportional to the common mode current flowing in the ground return line from or to the load, the current sensor having inputs coupled to respective legs of the DC bus and an output driving the transistor switching stage, the transistor switching stage comprising two transistors driven by said output of the current sensor whereby one of said transistors is turned on by said current sensor output depending on the direction of common mode current in said DC bus, a capacitor coupling said transistor switching stage and said ground return line and wherein said current sensor and said switching stage are coupled in a feed forward arrangement whereby the switching stage is coupled across said DC bus between said rectifier and said current sensor, said capacitor providing a cancellation current to said ground return line from said transistor switching stage to substantially cancel the common mode current in said ground return line, said transistor switching stage and said current sensor having an amplitude gain of approximately unity, said current sensor comprising a current transformer having a primary connected in series with a respective leg of said DC bus, said two transistors of said transistor switching stage comprising two complementary type transistors coupled such that a corresponding main electrode of each transistor are coupled together in a common connection, another corresponding main electrode of each transistor being coupled to a respective secondary of each of said current transformer and wherein the control electrodes of said transistors are coupled to respective legs of said DC bus.

    ACTIVE COMMON MODE EMI FILTERS
    26.
    发明专利
    ACTIVE COMMON MODE EMI FILTERS 未知

    公开(公告)号：AU2003228784A1

    公开(公告)日：2003-11-17

    申请号：AU2003228784

    申请日：2003-04-29

    Applicant: INT RECTIFIER CORP

    Inventor： TAKAHASHI TOSHIO ,  PELLY BRIAN

    IPC: H02M1/12 ,  H02M1/14 ,  H02M1/15 ,  H02M1/44 ,  H02M5/458 ,  H03H11/04

    Abstract: An active EMI filter for reducing common mode noise current in a circuits, comprising: a transistor stage having two transistors coupled in series, a current sensor for sensing the common mode noise current, the current sensor having an output driving the transistor stage, whereby each of the transistors is driven in response to the common mode noise current, a capacitor coupling the transistor stage and the ground return line, the capacitor providing a cancellation current to cancel the common mode noise current, the current sensor comprising a current transformer having a primary coupled with the circuit having the common mode noise. The current sensor and the transistor stage may be coupled in a feed forward arrangement wherein the transistor stage and the current sensor have an amplitude gain of approximately unity; or in a feedback arrangement wherein the transistor stage and current sensor provide high gain.

    28.
    发明专利
    未知

    公开(公告)号：DE10125910B4

    公开(公告)日：2007-02-01

    申请号：DE10125910

    申请日：2001-05-28

    Applicant: INT RECTIFIER CORP

    Inventor： TAKAHASHI TOSHIO

    IPC: G01R31/02 ,  G01R31/34 ,  G01R15/18 ,  G01R31/06 ,  G01R31/12 ,  G01R31/14 ,  H02P27/06

    Abstract: Motor insulation degradation is determined using circuitry to sense the common mode leakage current from the ground wire cable. In a preferred embodiment of the invention, a small current transformer detects the common mode leakage current flowing in the ground wire cable of the motor controller circuit. A single pole low pass filter generates an average leakage current signal from the sensed current. The average leakage current signal is converted to a PWM signal. A pulse generator receives the PWM signal and generates pulse signals at the rising and falling edges of the PWM signal. A pair of level shifters receive the rising edge and falling edge pulse signals and transpose those signals from a floating high voltage to a voltage referenced to ground. A pulse reconstruction circuit receives the level shifted pulse signals and reconstructs a pulse width modulated signal having a duty cycle which varies with respect to the magnitude of the common mode leakage current. This output signal is input directly to a microcontroller or a digital signal processor to calculate and determine the amount of motor insulation degradation.

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