Phase current sensor using inverter leg shunt resistor
AssigneeTexas Instruments Incorporated
InventorZhenyu Yu
Life of this patent
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Abstract
A method for use in a pulse width modulation controlled voltage-source inverter having one or more legs, each leg including two transistors coupled serially between the terminals of a power source and providing a respective drive output, each leg further including a shunt resistor between one of the two transistors, denominated the lower transistor, and one of the terminals, in which control pulses are applied to each leg during a sequence of pulse periods. The method is for determining the phase current each leg supplies, and includes the following steps. The voltages are sampled across the shunt resistor in a plurality of sample periods. The voltages so sampled are averaged over the sample periods, and the phase current is determined from the average so derived.
Claims8
In a pulse width modulation controlled voltage-source inverter having one or more legs, each leg including two transistors coupled serially between the terminals of a power source and providing a respective drive output, each leg further including a shunt resistor between one of said two transistors, denominated the lower transistor, and one of said terminals, in which control pulses are applied to each leg during a sequence of pulse periods, a method for determining the phase current for each leg, comprising the steps of:
- sampling the voltage across said shunt resistor in a plurality of sample periods;
- and
- averaging the voltages so sampled over said sample periods, and determining the phase current from the average so derived.
In a pulse width modulation controlled voltage-source inverter having one or more legs, each leg including two transistors coupled serially between the terminals of a power source and providing a respective drive output, each leg further including a shunt resistor between one of said two transistors, denominated the lower transistor, and one of said terminals, in which control pulses are applied to each leg during a sequence of pulse periods, a method for determining the phase current for a leg, comprising the steps of:
- sampling the voltage across said shunt resistor for said leg in a plurality of sample periods to obtain a corresponding plurality of voltage sample values;
- accumulating the sum of said plurality of voltage sample values, to obtain a voltage sum value;
- determining a corresponding sum value for the current through said shunt resistor, using Ohm's Law;
- determining the average of the inverse duty cycles for said leg for said plurality of sample periods;
- and
- determining the phase current for each leg by dividing said current sum value by said inverse duty cycle average.
A system for providing pulse width modulation control, comprising:
- a voltage-source inverter circuit operable to drive a multi-phase component;
- a phase current detection circuit associated with the voltage-source inverter circuit, and adapted to provide a voltage related to a phase current of the multi-phase component;
- and
- a processor adapted to sample the voltage of the phase current detect circuit over a plurality of sample periods and use the sampled voltage to determine an average phase current for use in the control of the voltage-source inverter circuit.
Dependencies are inferred from the claim text.