US-20260126819-A1 - SYSTEM AND METHOD FOR ERROR COMPENSATION IN PULSE-WIDTH MODULATED SYSTEMS

Abstract

A gas flow regulation system is provided, the system comprising a solenoid valve configured to transition between an open position and a closed position, the solenoid valve comprising a solenoid; a power source; a switch configured to connect or disconnect the power source to the solenoid valve depending on a duty cycle of the system; and a controller comprising a memory storing: a mathematical model of an electrical circuit comprising the solenoid valve, the power source and the switch; and instructions to execute the following steps: determine a required value of current through the solenoid; measure a response of the electrical circuit to a testing signal; calculate, based on the required value of current through the solenoid, the response of the electrical circuit to the testing signal and the mathematical model of the electrical circuit, a compensation value to a duty cycle of the system; adjust the duty cycle of the system based on the compensation value.

Inventors

• Jan Ondrich

Assignees

• PITTWAY SARL

Dates

Publication Date

20260507

Application Date

20230525

Priority Date

20220610

Claims (20)

1. 1 . A gas flow regulation system, comprising: a solenoid valve configured to transition between an open position and a closed position, the solenoid valve comprising a solenoid; a power source; a switch configured to connect or disconnect the power source to the solenoid valve depending on a duty cycle of the system; and a controller comprising a memory storing: a mathematical model of an electrical circuit comprising the solenoid valve, the power source and the switch; and instructions to execute the following steps: determine a required value of current through the solenoid; measure a response of the electrical circuit to a testing signal; calculate, based on the required value of current through the solenoid, the response of the electrical circuit to the testing signal and the mathematical model of the electrical circuit, a compensation value to a duty cycle of the system; adjust the duty cycle of the system based on the compensation value.
2. 2 . The gas flow regulation system of claim 1 , wherein the compensation value is dependent on a switch-on time of the switch.
3. 3 . The gas flow regulation system of claim 1 , wherein the compensation value is dependent on a switch-off time of the switch.
4. 4 . The gas flow regulation system of claim 1 , wherein the compensation value is dependent on a difference between a switch-on time and a switch-off time of the switch.
5. 5 . The gas flow regulation system of claim 1 , wherein the instructions further comprise the following steps: create the mathematical model; store the mathematical model in the memory.
6. 6 . The gas flow regulation system of claim 1 , further comprising at least one of: an integrator, a diode, or a shunt resistor.
7. 7 . The gas flow regulation system of claim 1 , wherein the memory stores a first mathematical model and a second mathematical model, and wherein the instructions further comprise the following steps: determine whether the current flows through the circuit during the whole PWM period or whether the current drops to zero in the switch non-active phase; and select a model from the first and the second mathematical model based on determination whether the current flows through the circuit during the whole PWM period or whether the current drops to zero in the switch non-active phase.
8. 8 . A method of controlling a gas flow regulation system, the system comprising a solenoid valve configured to move between an open position and a closed position, the solenoid valve comprising a solenoid; a power source; a switch configured to connect or disconnect the power source to the solenoid valve depending on a duty cycle of the system; and a controller comprising a memory storing: a mathematical model of an electrical circuit comprising the solenoid valve, the power source and the switch; the method comprising: determining, by the controller, a required value of current through the solenoid; measuring, by the controller, a response of the electrical circuit to a testing signal; calculating, by the controller, based on the required value of current through the solenoid, the response of the electrical circuit to the testing signal and the mathematical model of the electrical circuit, a compensation value to a duty cycle of the system; adjusting, by the controller, the duty cycle of the system based on the compensation value.
9. 9 . The method of claim 8 , wherein the method further comprises: measuring dependency of a difference between the duty cycle instructed by the controller and the duty cycle of the system on a switch-on time of the switch; and determining the compensation value based on the measured dependency.
10. 10 . The method of claim 8 , wherein the method further comprises: measuring dependency of a difference between the duty cycle instructed by the controller and the duty cycle of the system on a switch-off time of the switch; and determining the compensation value based on the measured dependency.
11. 11 . The method of claim 8 , wherein the method further comprises: measuring dependency of a difference between the duty cycle instructed by the controller and the duty cycle of the system on a difference between a switch-on time and a switch-off time of the switch; and determining the compensation value based on the measured dependency.
12. 12 . The method of claim 8 , wherein the method further comprises: creating, by the controller, the mathematical model; storing, by the controller, the mathematical method in the memory.
13. 13 . The method of claim 8 , wherein the system further comprises at least one of: an integrator, a diode, or a shunt resistor.
14. 14 . The method of claim 8 , wherein the memory stores a first mathematical model and a second mathematical model, and wherein the method further comprises: determining, by the controller, whether the current flows through the circuit during the whole PWM period or whether the current drops to zero in the switch non-active phase; and selecting, by the controller, a model from the first and the second mathematical model based on determination whether the current flows through the circuit during the whole PWM period or whether the current drops to zero in the switch non-active phase.
15. 15 . The gas flow regulation system of claim 2 , wherein the instructions further comprise the following steps: create the mathematical model; store the mathematical model in the memory.
16. 16 . The gas flow regulation system of claim 2 , further comprising at least one of: an integrator, a diode, or a shunt resistor.
17. 17 . The gas flow regulation system of claim 3 , further comprising at least one of: an integrator, a diode, or a shunt resistor.
18. 18 . The gas flow regulation system of claim 4 , further comprising at least one of: an integrator, a diode, or a shunt resistor.
19. 19 . The method of claim 9 , wherein the method further comprises: measuring dependency of a difference between the duty cycle instructed by the controller and the duty cycle of the system on a switch-off time of the switch; and determining the compensation value based on the measured dependency.
20. 20 . The method of claim 10 , wherein the method further comprises: measuring dependency of a difference between the duty cycle instructed by the controller and the duty cycle of the system on a difference between a switch-on time and a switch-off time of the switch; and determining the compensation value based on the measured dependency.

Description

FIELD OF THE INVENTION The present invention relates to systems and methods for error compensation in pulse-width modulated (PWM) systems, in particular solenoid valves. BACKGROUND OF THE INVENTION Many systems are based on a pulse-width modulation (PWM) technique. PWM is a method of reducing the average power delivered by an electrical signal, and it is simple and efficient way to achieve a specific output value of a process with low cost. The average value of voltage (and current) fed to the load is controlled by turning the switch between supply and load on and off at a fast rate The total power supplied to the load depends on the on/off times (active and non-active phases) of the switch. One specific application of a PWM system is a solenoid valve. A solenoid valve may be used to control (regulate) flow of a fluid, e.g. gas. In solenoid valve, intensity of the magnetic field which creates the force for the opening of the valve is equivalent to the average value of the electric current of the winding. The valve often has a spring or other element acting against this force to close the valve in case no current is supplied to the valve. Electric current through the solenoid valve must meet certain minimal value to ensure that the valve is open. The existing systems often compensate for e.g. influence of a supply voltage change or an influence of an ambient temperature. This is mainly achieved by a simple voltage feedback so that the current (which is proportional to the voltage as well as the force opening the valve) can be regulated. One of the problems with existing PWM systems as applied to solenoid valves is that the components of the circuitry are not ideal. Existing systems compensating for the non-ideal behaviour of the components usually utilize a table with characteristic data of the system (thus being a system which is not self-adaptable) and/or they require complex signal processing and/or they require additional components such as pressure sensor, temperature sensor and the like. Therefore, there is a need to provide a simple yet accurate system and method of regulating the PWM system which would mitigate the above-mentioned situation. SUMMARY OF THE INVENTION In a first aspect of the invention, a gas flow regulation system is provided, the system comprising a solenoid valve configured to transition between an open position and a closed position, the solenoid valve comprising a solenoid; a power source; a switch configured to connect or disconnect the power source to the solenoid valve depending on a duty cycle of the system; and a controller comprising a memory storing: a mathematical model of an electrical circuit comprising the solenoid valve, the power source and the switch; and instructions to execute the following steps: determine a required value of current through the solenoid; measure a response of the electrical circuit to a testing signal; calculate, based on the required value of current through the solenoid, the response of the electrical circuit to the testing signal and the mathematical model of the electrical circuit, a compensation value to a duty cycle of the system; and adjust the duty cycle of the system based on the compensation value. In an embodiment of the first aspect, the compensation value in the gas flow regulation system is dependent on a difference between a switch-on time and a switch-off time of the switch. In a second aspect of the invention, a method of controlling a gas flow regulation system, the system comprising a solenoid valve configured to move between an open position and a closed position, the solenoid valve comprising a solenoid; a power source; a switch configured to connect or disconnect the power source to the solenoid valve depending on a duty cycle of the system; and a controller comprising a memory storing: a mathematical model of an electrical circuit comprising the solenoid valve, the power source and the switch; the method comprising: determining, by the controller, a required value of current through the solenoid; measuring, by the controller, a response of the electrical circuit to a testing signal; calculating, by the controller, based on the required value of current through the solenoid, the response of the electrical circuit to the testing signal and the mathematical model of the electrical circuit, a compensation value to a duty cycle of the system; and adjusting, by the controller, the duty cycle of the system based on the compensation value. In an embodiment of the second aspect, the method may further comprise: measuring dependency of a difference between the duty cycle instructed by the controller and the duty cycle of the system on a difference between a switch-on time and a switch-off time of the switch; and determining the compensation value based on the measured dependency. Other embodiments are defined in the claims and described in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS Specific embodiments of t