Switch-mode synthetic power inductor
View Patent ↗A fuel delivery system for a vehicle includes a fuel injector that meters fuel flow and provides for preheating fuel to aid combustion. A control circuit including a synthetic inductor drives a heated element within the fuel flow.
1. A fuel delivery system comprising:
a fuel injector metering fuel to an energy conversion device, the fuel injector including an inductor for an inductively energized heating element for heating the fuel; and
a controller including a driver circuit for driving metering of fuel and for energizing the inductor of the heating element, the driver circuit for energizing the inductor of the heating element including a switch-mode synthetic inductor, which resolves the time-domain inductor behavior according to the equation:
i
=
1
L
∫
-
∞
t
v
(
τ
)
ⅆ
τ
where i=is the current as a function of the integral in time of v, or voltage across the inductor, and some multiplier equivalent to 1/L, the synthetic inductor further comprising a current sense resistor connected between a power source for the controller and a power circuit, which is coupled to the inductor for the heating element and configured to provide current to said inductor from the power source for the controller, the voltage, v, across the inductor being proportional to a voltage across the current sense resistor.
2. The fuel delivery system as recited in claim 1 , further comprising a gate driver, said gate driver receiving a PWM signal and operating a power switching device that controls power to the power circuit energizing the heated element.
3. The fuel delivery system as recited in claim 2 , including an output filter that receives that removes modulation from the power output by the power switching device.
4. The fuel delivery system as recited in claim 2 , including an integrator for comparing a value indicative to a desired inductance to a value indicative of an actual induction value, the integrator generating an error output indicative of a difference between the desired inductance and the actual inductance.
5. The fuel delivery system as recited in claim 4 , including an error amplifier receiving the error output from the integrator generating the input to the comparator to produce the PWM signal.
6. The fuel delivery system as recited in claim 1 , wherein the power circuit includes an output filter including an inductor and capacitor for modifying a modulation signal provided to the power circuit such that the heating element receives an output proportional to an input signal.
7. The fuel delivery system as recited in claim 6 , wherein the power circuit generates a virtual resistance value of the inductor by multiplying the current measured by the current-sense resistor by a resistance value such that when the desired virtual loss is higher, the sensed current is artificially increased.
8. A heated fuel injector control circuit comprising:
a coil, configured to provide a time varying magnetic field within a heated element of a fuel injector; and
a switch-mode synthetic inductor controlling power provided to the coil, which resolves the time-domain inductor behavior according to the equation:
i
=
1
L
∫
-
∞
t
v
(
τ
)
ⅆ
τ
where i=is the current as a function of the integral in time of v, or voltage across the coil and some multiplier equivalent to 1/L, the synthetic inductor further comprising a current sense resistor connected between a power source for the controller and a power circuit, which is coupled to the coil and configured to provide current to said coil from the power source for the controller, the voltage, v, across the coil being proportional to a voltage across the current sense resistor.
9. The heated fuel injector control circuit as recited in claim 8 , including a gate driver receiving a PWM control signal and controlling operation of the power circuit responsive thereto.
10. The heated fuel injector control circuit as recited in claim 9 , including an integrator that compares a signal indicative of a desired inductance to a signal indicative of an actual inductance and generates and error signal indicative of a difference between the desired inductance and the actual inductance.
11. The heated fuel injector control circuit as recited in claim 10 , including an error amplifier receiving the error signal from the integrator and outputting an amplified signal to the comparator.
12. The heated fuel injector control circuit as recited in claim 11 , wherein the comparator combines the amplified signal from the error amplifier and a triangle wave from a wave generator and generates the PWM control signal for producing a time varying magnetic field within the heated element such that the fuel is heated to a desired temperature.
13. The heated fuel injector as recited in claim 12 , wherein a gain of the error amplifier includes a value indicative of a resistance of the inductor.
14. The heated fuel injector as recited in claim 8 , wherein the power circuit includes an output filter including an inductor and capacitor for modifying a modulation signal provided to the power circuit such that the heating element receives an output proportional to an input signal.
15. The heated fuel injector as recited in claim 14 , wherein the power circuit generates a virtual resistance value of the inductor by multiplying the current measured by the current-sense resistor by a resistance value such that when the desired virtual loss is higher, the sensed current is artificially increased.