Browse Prior Art Database

Control for resonance converter

IP.com Disclosure Number: IPCOM000130031D
Publication Date: 2005-Oct-11
Document File: 2 page(s) / 25K

Publishing Venue

The IP.com Prior Art Database

Abstract

This paper concerns control of a resonance converter, which with a resonant DC-circuit converts electric energy from an AC source into DC-supply at the output. The DC supply is achieved by continuously switching a DC voltage with two alternately switching MOSFET switches. Then the voltage is scaled to the output in a transformer. The innovation in the circuit resides in a current measurement by use of yet another transformer.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 50% of the total text.

Abstract

This paper concerns control of a resonance converter, which with a resonant DC-circuit converts electric energy from an AC source into DC-supply at the output. The DC supply is achieved by continuously switching a DC voltage with two alternately switching MOSFET switches. Then the voltage is scaled to the output in a transformer. The innovation in the circuit resides in a current measurement by use of yet another transformer.

With this construction it is possible to deliver a constant electric energy to a device at the output, electrically represented as a load at the output. This load could represent several electric devices that requires a constant and stable input electric energy. Converters like this therefore have several fields of use.

Prior art

In order to keep the output at a stable level in a converter like this it is required to incorporate some control of the output voltage and current. This is done with a feedback signal from the output that is compared to a reference signal given by the user. A control circuit do this and regulate the output signal according to the difference. This is a well known technical problem in the art, and several solutions to it have been proposed. Among these are US3953779, where the purpose is to limit the peak values for the current and voltage, in this way reducing the electrical loss in the converter thereby improving the efficiency.

Another example is US4694383, where the output power is regulated as a function of the output voltage. This relation between the output power as a function of the output voltage can be unlinear in some working areas. This invention seeks through current and voltage feedback circuits to make this relation between output voltage and power more linear, thus giving a more reliable working area. A comparator generates control signals for the switches from this relation, which should make the output power more stable.

If the converter should be an AC-DC converter, it would be advantageous to place a rectifier at the output. This could be a Wheatstone bridge with diodes. An example of a switching resonant converter, with four switches, a transformer and a rectifier at the output, is shown in US4935857.

Description of the new resonance converter

The purpose of the design described in this paper is to make a converter, which through a more linear relationship between output voltage and output power can give a stable output, using the advantage that a more linear relationship between output voltage and output power makes the converter easier to control. 

A principle circuit diagram can be seen in figure 1. The voltage-controlled oscillator or VCO is an electronic circuit whose purpose is to generate a repeating voltage waveform, which results in a stable output, V0. The VCO uses feedback from the resonant circuit and amplification of the returned signal to generate this output.There are several possibilities for feedback to this circuit. Such as current and voltage fee...