Plasma display panel

• US 20040178809A1
• Filed: 12/18/2003
• Published: 09/16/2004
• Est. Priority Date: 12/19/2002
• Status: Active Grant

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Goto, Kohsei, Sakano, Junichi, Innami, Toshiyuki, Fujino, Shinichi
• Granted Patent: US 7,138,778 B2
• Time in Patent Office: Days
• US Class Current: 324/710
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current

Abstract

A current sensor has a power MOSFET Q1, connected between an electric load and a power supply, for controlling current that flows through said electric load, a mirror MOSFET Q2, connected in parallel to said power MOSFET Q1, in which a portion of the current flowing through said power MOSFET flows, and a current detection resistor RC connected between a source electrode of said power MOSFET and a source electrode of said mirror MOSFET. An inverting amplifier circuit CP of the current sensor 3 inverts and amplifies the voltage signal, which has been converted to voltage by the current detection resistor RC, and outputs the signal, thereby converting positive and nega tive voltages generated across the current detection resistor RC to a positive voltage.

Claims

1. A current sensor comprising

a power MOSFET connected between an electric load and a power source, for controlling current that flows through said electric load,

a mirror MOSFET connected in parallel to said power MOSFET, wherein a portion of the current that flows through said power MOSFET flows,

a current detection resistor con nected between a source electrode of said power MOSFET and a source electrode of said mirror MOSFET, and

a converting means for converting positive and negative voltages generated across said current detection resistor into a positive or negative voltage.

2. A current sensor according to claim 1, wherein

said converting means is an inverting amplifier circuit that inverts and amplifies a voltage signal, which has been converted into voltage by said current detection resistor, and outputs the signal.

3. A current sensor according to claim 1, wherein

said converting means is a level converting circuit that increases or decreases the level of the voltage signal, which has been converted into voltage by said current detection resistor.

4. A current sensor according to claim 1, wherein

the resistance value of said current detection resistor is determined so that a value obtained as the result of the current Imain, which flows through said power MOSFET or a parasitic diode of said power MOSFET, being divided by the mirror ratio X of said power MOSFET to said mirror MOSFET and then multiplied by the resistance value Rrc of said current detection resistor is less than the voltage drop value VD of said power MOSFET or the parasitic diode of said po wer MOSFET when said current is flowing.

5. A current sensor comprising

a power MOSFET, connected between an electric load and a power source, for controlling current that flows through said electric load,

a mirror MOSFET, connected in parallel to said power MOSFET, wherein a portion of the current that flows through said power MOSFET flows,

a current detection resistor connected between a source electrode of said power MOSFET and a source electrode of said mirror MOSFET, and

a converting means for converting positive and negative voltages generated across said current detection resistor into digital signals.

6. A PWM inverter having

three phases of arms, connected in parallel to a DC power source, each phase consisting of an upper arm and a lower arm which function in pairs so as to control alternating current, and

current sensors disposed at either all of the upper arms or the lower arms of said three phases, wherein

said current sensor consists of

a power MOSFET, connected between an el ectric load and a power source, for controlling current that flows through said electric load,

a mirror MOSFET, connected in parallel to said power MOSFET, wherein a portion of the current that flows through said power MOSFET flows,

a current detection resistor connected between a source electrode of said power MOSFET and a source electrode of said mirror MOSFET, and

a converting means for converting positive and negative voltages generated across said current detection resistor into a positive or negative voltage;

and

said PWM inverter further having

a driving device for detecting current of each phase based on the current detection signal outputted from said current sensor of each phase when all of the arms located on the opposite side of the arms wher e said current sensors are disposed are turned OFF within the PWM switching period, thereby controlling alternating current.