Compact, configurable power supply for energizing ozone-producing cells
Improvements in the supply of high-frequency electrical power to ozone-producing cells can be accomplished using the systems and techniques described herein. Application of a DC-DC converter operating at a switching frequency substantially greater than a load frequency, supports generation of a high-voltage AC for powering such cells, while allowing for reductions in component size and reductions in a quality factor of a load tuning circuit. Controllable power inverters used in obtaining one or more of the switching and load frequencies can be controlled using feedback techniques to provide stable, high-quality power to ozone-producing cells under variations in one or more of externally supplied power and load conditions. An inrush protection circuit can also be provided to selectively introduce a current-limiting resistance until an input DC bus has been sufficiently initialized as determined by measurements obtained from the DC bus. The current limiting resistance can be a positive-temperature coefficient thermistor.
1. A power system for powering at least one ozone-producing cell, comprising:
a rectifier configured to rectify an AC input voltage;
a bus capacitor coupled in parallel to the rectifier, the bus capacitor configured to develop an unregulated DC voltage in response to rectified AC input voltage;
a power converter coupled to the bus capacitor and configured to produce a high-frequency AC output voltage in response to the unregulated DC voltage, when coupled to the at least one ozone-producing cell;
a first sensor configured to measure a voltage across the bus capacitor;
a second sensor configured to measure a current between the rectifier and the bus capacitor; and
a controllable current-limiting resistance coupled between the rectifier and the bus capacitor, the controllable current limiting resistance also in communication with each of the first and second sensors and configured to provide a current limiting resistance during initialization and a substantial short circuit once initialized.
2. The power system of claim 1 , wherein the controllable current-limiting resistance comprises a series resistor coupled in parallel with a controllable switch, the controllable switch in communication with the first and second sensors, being open during initialization and closed once initialized.
3. The power system of claim 2 , wherein the controllable switch comprises a semiconductor device.
4. The power system of claim 2 , wherein the series resistor comprises a positive temperature coefficient (PTC) thermistor.
5. The power system of claim 1 , wherein the controllable current-limiting resistance is part of an inrush current protection circuit which provides inrush current protection in the power converter at power-up.
6. A method for supplying power to at least one ozone-producing cell, comprising:
rectifying an AC input voltage;
charging by the rectified AC input voltage a bus capacitor to a DC operating voltage;
converting the DC operating voltage to a high-frequency AC voltage when applied to the at least one ozone-producing cell;
differentiating between an initialization state of the bus capacitor and an initialized state of the bus capacitor, the differentiating comprising measuring a voltage across the bus capacitor to determine a measured voltage and measuring a current flowing into the bus capacitor to determine a measured current; and
varying a series resistance in response to the measured voltage and the measured current, the series resistance limiting current to the bus capacitor during initialization, otherwise allowing unrestricted current when initialized.
7. The method of claim 6 , wherein the differentiating further comprises:
comparing the measured voltage to a voltage threshold; and
comparing the measured current to a current threshold; wherein,
if the measured voltage is above the threshold voltage and the measured current is below the current threshold then the initialized state is indicated.
8. The method of claim 6 , wherein the differentiating and varying steps are part of an inrush current protection process which provides inrush current protection at power-up.