Offset compensation for flow sensing devices
AssigneeSensortechnics GmbH
InventorsGennadiy FROLOV, Oleg GRUDIN
Life of this patent
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Abstract
There is described herein a flow sensing device having offset compensation and an offset compensation method, the flow sensing device having two separate and independent thermal flow sensors, each containing a heater and at least one temperature-sensitive element. The components of the two thermal flow sensors are connected such that flow-dependent contributions of each sensor into a common output signal have opposite signs after passing through a subtracting node. Heating pulses are applied to the heaters of the two thermal flow sensors out of phase, and an output signal is measured for each heat pulse applied. A net output signal is then determined by calculating a difference between a last output reading and at least one previous output reading.
Claims16
A method of offset compensation for a flow sensing device having a first thermal flow sensor with a first heater and at least a first temperature sensitive element and a second thermal flow sensor with a second heater and at least a second temperature sensitive element, the first thermal flow sensor and the second thermal flow sensor being separate and independent, measuring a same flow, and generating flow-dependent signals, the method comprising:
- applying heating pulses (i) to the first heater and the second heater alternatingly such that when the first heater is turned on, the second heater is turned off and when the second heater is turned on, the first heater is turned off;
- forming an output signal Vout from the flow-dependent signals such that contributions of the flow-dependent signals have opposite signs of sensitivity to flow:
- measuring and storing the output signal Vout of the flow sensing device at each one of the heating pulses (i);
- and
- determining a net output signal Vnet by subtracting at least one previous output signal reading Vout(i−1) from a last output signal reading Vout(i).
A flow sensing device having a compensated offset, the device comprising:
- a circuit having a first thermal flow sensor with a first heater and at least a first temperature sensitive element and a second thermal flow sensor with a second heater and at least a second temperature sensitive element, the first thermal flow sensor and the second thermal flow sensor being separate and independent, measuring a same flow, and generating flow-dependent signals of opposite signs that combine to form an output signal Vout;
- a heating module connected to an input of the circuit and configured to apply heating pulses (i) to the first heater and the second heater alternatingly such that when the first heater is turned on, the second heater is turned off and when the second heater is turned on, the first heater is turned off;
- an output module connected to an output of the circuit for measuring and storing the output signal Vout at each heating pulse (i) and determining a net output signal Vnet by subtracting at least one previous output signal reading Vout(i−1) from a last output signal reading Vout(i)
Dependencies are inferred from the claim text.