Isolation impedance measuring system and method using fourier transform and component value self calibration
AssigneeMaxim Integrated Products, Inc.
InventorsJiangang Liu, Jason Allen Wortham
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Abstract
Embodiments of the present invention disclose methods and systems in a vehicle having high voltage (HV) for measuring isolation impedance in an EV or HEV utilizing an AC impedance measurement system. The method utilizes an extraction algorithm based on a Fourier transform to calculate phase and amplitude and then utilizes the calculated phase and amplitude to determine the isolation impedance. The isolation impedance comprises leakage resistance and total capacitance that are coupled in parallel between the high voltage system and the chassis. Embodiments of the present invention also provide a method and systems for component value self-calibration.
Claims20
A method for determining isolation impedance, the method comprising:
- receiving at a voltage node a waveform signal that is representative of a first voltage;
- and
- extracting amplitude and phase information from the waveform signal;
- utilizing the amplitude and phase information to determine an isolation impedance between a second voltage and a ground potential, the second voltage being coupled to the voltage node and being higher than the first voltage.
A system for determining isolation impedance, that system comprising:
- a signal source that generates an excitation signal, the excitation signal is coupled to a high voltage system via a first impedance;
- a measuring system that measures a waveform signal at a voltage node that is coupled to the first impedance;
- and
- a processor that calculates an isolation impedance between the high voltage system and a ground potential based on the waveform signal.
A method for a self-calibrating procedure for a high voltage system in an electric vehicle or a hybrid electric vehicle, the method comprising:
- based on different waveform signals at a voltage node that is coupled to a high voltage system, each waveform signal being associated with a different circuit configuration,
- extracting amplitude and phase information from a cycle of the waveform signals by utilizing one of a Discrete Fourier Transform and a Fourier Transform;
- and
- utilizing the amplitude and phase information to calculate at least one of component value initial tolerance and temperature coefficients.
Dependencies are inferred from the claim text.