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Method for reducing magnetic field emissions for heated seats and other applications

A power and load path technology, applied in vehicle seats, ohmic resistance heating, emergency protection circuit devices for limiting overcurrent/overvoltage, etc., can solve problems such as high electromagnetic emission or interference, and electromagnetic emission problems

Pending Publication Date: 2022-03-22
HELLA KG HUECK & CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, when the heating pad is energized, electromagnetic emissions or interference can be undesirably high, sometimes exceeding the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines for time-varying electromagnetic fields
Since the resistance of a heating pad varies with temperature, electromagnetic emissions can be especially problematic at lower temperatures when the heating pad resistance decreases

Method used

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  • Method for reducing magnetic field emissions for heated seats and other applications
  • Method for reducing magnetic field emissions for heated seats and other applications
  • Method for reducing magnetic field emissions for heated seats and other applications

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Embodiment Construction

[0016] I. Ohmic operation of power MOSFETs

[0017] In this embodiment, power MOSFETs are used as switches for controlling the flow of power to electrical loads, and in particular resistive heating elements for electric seat heaters. As known in the art, a MOSFET is a three-terminal device in which the gate voltage controls the flow of current between the source and drain. The systems and methods of the present invention limit electromagnetic emissions and interference from power seat heaters by operating a power MOSFET in its ohmic region. Before discussing the system and method in more detail, the general operation of a power MOSFET in its ohmic region will now be described.

[0018] refer to figure 1 , shows the output characteristics of an exemplary power MOSFET, where the drain-source current (I DS ), and the drain-source voltage (V DS ). In the ohmic region (left), the drain-source current (I DS ) vs. drain-to-source voltage (V DS ) follows Ohm's law, since the ...

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Abstract

A system and method for controlling a power MOSFET in order to limit electromagnetic interference from a load is provided. The systems and methods include a pulse width modulation (PWM) control voltage to operate a power MOSFET according to an ohmic region (linear mode) of the power MOSFET. By operating the power MOSFET in the ohmic region of the power MOSFET, the electromagnetic field generated by the load is reduced without the need for a dedicated DC / DC converter that would otherwise increase the cost, size and weight of the power electronics.

Description

[0001] Cross References to Related Applications [0002] This application claims the benefit of US Provisional Application 62 / 882,001, filed August 2, 2019, the disclosure of which is incorporated by reference in its entirety. technical field [0003] The present invention relates to the operation of power MOSFETs in switching applications to reduce emissions and interference from electromagnetic fields, optionally in temperature controlled vehicle seats. The invention can also reduce inrush current or inrush current for capacitive and inductive loads, thereby providing cost savings for switching operations. Background technique [0004] Electric seat heaters for motor vehicles include heatmats for converting electrical energy into heat. The heating mat includes resistive heating elements positioned proximate the trim cover, generally in a spiral pattern. Modern heating mats are characterized by a short warm-up phase and even heat distribution for comfort in cold weather c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M1/08H02M1/44H02M1/32H02H9/02
CPCH02M1/08H02M1/44H02M1/32H02H9/02H02H9/025H03K17/165H03K2217/0072H02M1/0045B60N2/5685H05B1/0219H05B1/0238H05B3/0019H05B2203/029
Inventor D·K·蒙达尔
Owner HELLA KG HUECK & CO