Method for reducing magnetic field emission for heated seats and other applications
AssigneeHella GmbH & Co. KGaA
InventorDebabrato Kumar Mondal
Life of this patent
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Abstract
A system and a method for controlling a power MOSFET for limiting electromagnetic interference from a load is provided. The system and method include a pulse-width-modulated (PWM) control voltage to operate the power MOSFET in accordance with its Ohmic region (linear mode). By operating the power MOSFET in its Ohmic region, the electromagnetic field generated by the load is reduced, without requiring a dedicated DC/DC converter that would otherwise increase the cost, size, and weight of the power electronics.
Claims13
A method for pulse-width-modulated (PWM) control of a power MOSFET having a load path, the method comprising:
- (a) providing an electrical load that is series connected with the load path of the power MOSFET;
- (b) activating the power MOSFET with a PWM gate voltage, the PWM gate voltage having a frequency and a duty cycle;
- (c) measuring the current in the load path of the power MOSFET during activation of the power MOSFET;
- (d) comparing the measured current in the load path of the power MOSFET with a current limit value;
- (e) iteratively decreasing a frequency of the PWM gate voltage and increasing a duty cycle of the PWM gate voltage until the measured current in the load path is determined to exceed the current limit value;
- and
- (f) if the measured current in the load path is not less than the current limit value, reverting to an immediately previous frequency or duty cycle of the PWM gate voltage.
A system for pulse-width-modulated (PWM) control of a power MOSFET, the system comprising:
- a power MOSFET having a load path;
- an electrical load that is series connected with the load path of the power MOSFET;
- a current sensor adapted to measure a current value in the load path of the power MOSFET;
- a voltage source adapted to provide a variable PWM gate voltage to the power MOSFET,
- wherein the voltage source is operable to iteratively decrease a frequency of the PWM gate voltage and iteratively increase a duty cycle of the PWM gate voltage until a measured current in the load path is determined to exceed a current limit value based on the output of the current sensor.
Dependencies are inferred from the claim text.