Synchronized array power oscillator with leg inductors
View Patent ↗An electronic high frequency induction heater driver, for a variable spray fuel injection system, uses a scalable array of zero-voltage switching oscillators that utilize full and half-bridge topology with inductors between semiconductor switches wherein the semiconductor switches are synchronous within each bridge for function, and each bridge is synchronized for function along the entire array. The induction heater driver, upon receipt of a turn-on signal, multiplies a supply voltage through a self-oscillating series resonance, wherein one component of each tank resonator circuit comprises an induction heater coil magnetically coupled to an appropriate loss component so that fuel inside a fuel component is heated to a desired temperature.
1. A synchronized array power oscillator for an electronic induction heater driver, the synchronized array power oscillator comprising:
an H-bridge circuit comprising high-side and low-side semiconductor switches and a resonant tank circuit comprising a tank circuit inductor and tank circuit capacitor, the resonant tank circuit being electrically connected between legs of the H-bridge circuit via first and second leg inductors, each leg inductor being electrically in series with an adjacent high-side switch and low-side switch and connected to the tank circuit inductor, the tank circuit inductor configured to be able to inductively heat a fuel injector;
a plurality of half-bridge circuits, each half-bridge circuit comprising high-side and low-side semiconductor switches and a corresponding tank circuit inductor configured to inductively heat a corresponding fuel injector, each half-bridge circuit further comprising a corresponding leg inductor connected in series with the high-side and low-side semiconductor switches of each half-bridge circuit, the plurality of half-bridge circuits being connected in parallel to the H-bridge circuit and connected in parallel to each other, adjacent pairs of half-bridge circuits forming a virtual H-bridge circuit, which is synchronized with the H-bridge circuit;
wherein the H-bridge circuit and the half-bridge circuits are configured to provide current to a first end of the tank circuit inductors during a first half of a sine wave and provide current to an opposite second end of the tank circuit inductors during a second half of the sine wave; and
wherein bridge switch timing is determined by a synchronized frequency of resonant tank circuits.
2. The synchronized array power oscillator of claim 1 , wherein the first and second leg inductors are between the resonant tank circuit and the high-side switches of the H-bridge circuit to source current to the resonant tank circuit from a voltage source.
3. The synchronized array power oscillator of claim 2 , wherein the first and second leg inductors are between the resonant tank circuit and the low-side switches of the H-bridge circuit to sink current from the resonant tank circuit to an absolute voltage sink having a voltage that is less than the voltage source.
4. The synchronized array power oscillator of claim 1 , wherein H-bridge synchronization is accomplished through rectifier diodes sinking charge from one leg of a bridge circuit to an opposite leg of the bridge circuit.
5. The synchronized array power oscillator of claim 1 , wherein bridge synchronization is accomplished through resistors sourcing charge from a voltage supply.
6. The synchronized array power oscillator of claim 1 , wherein an inductance of each of the at least two leg inductors is greater than an inductance of at least one of the tank circuit inductors.
7. The synchronized array power oscillator of claim 1 , wherein an inductance of each of the at least two leg inductors is more than twice an inductance of at least one of the tank circuit inductors.