JP2016046665A - Resonance circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resonance circuit which can be stably used for high frequency power and is frequency-adjustable.SOLUTION: The resonance circuit includes a capacitor and also includes a temperature control section which heats or cools the capacitor. A resonant frequency of the resonance circuit is detected and fed back to the temperature control section, a temperature of the capacitor is controlled and a capacity is changed, thereby controlling the resonant frequency.SELECTED DRAWING: None

Description

  The present invention relates to a resonance circuit capable of adjusting a resonance frequency, and more particularly to a resonance circuit for a high frequency power circuit.

  Class D amplifiers and class E amplifiers having high power efficiency are used in output circuits such as transmitters that output large high-frequency power. Usually, the output of these amplifiers is accompanied by an LC resonance circuit that passes the output power (for example, Patent Document 1).

  In the case of using such an LC resonance circuit, there is a method of tuning to a target frequency by changing the capacitance of a capacitor in the resonance circuit.

  The resonance frequency of the LC resonance circuit may fluctuate due to external factors such as the influence of heat generation or load during operation, ambient temperature or humidity, and aging.

  In order to keep the resonance frequency constant, a method using a mechanical variable capacitor is employed, particularly in a power circuit, avoiding a semiconductor product that is weak against heat. In addition, water-cooled capacitors for such power circuits are commercially available.

  Patent Document 1 discloses a multilayer ceramic capacitor provided with a heating element, and discloses a method for controlling the temperature of the capacitor body to be constant.

International Publication WO2013 / 111243 JP-A-5-101964

  A resonance circuit that adjusts to a target resonance frequency by changing the capacitance of a capacitor, such as an LC resonance circuit, is used. Among these, mechanical variable capacitors are used particularly for high-frequency power applications involving heat generation of capacitors. Since the mechanical variable capacitor has a sliding portion, there is a problem that it is likely to deteriorate over time. Further, a drive system for the mechanical part is required.

  The present invention has been made in view of the above circumstances, and provides a resonant circuit capable of frequency adjustment that can be stably used for high-frequency power applications without the need to include the mechanical variable capacitor and its drive system. With the goal.

That is, the present invention includes the following inventions.
(1) A resonant circuit including a capacitor,
Including a temperature control to heat or cool the capacitor;
By detecting the resonance frequency of the resonance circuit and feeding it back to the temperature control unit, by controlling the temperature of the capacitor and changing the capacitance,
A resonance circuit characterized by controlling a resonance frequency.

(2) The resonance circuit according to (1), wherein the capacitor is a liquid-cooled capacitor, and the temperature or flow rate of the coolant flowing through the liquid-cooled capacitor is adjusted to control the temperature of the capacitor.

  The resonant circuit of the present invention can be adjusted in frequency and can be stably used for high frequency power applications.

  In general, a capacitor has a temperature dependency of a capacitance, although the degree varies depending on the type. The present invention uses the temperature dependency to change the capacitance of the capacitor by raising and lowering the capacitor constituting the LC resonance circuit to an appropriate temperature, and control the resonance frequency of the resonance circuit to a target frequency. To do.

  A commercially available capacitor | condenser can be used for the capacitor | condenser used for this invention. As the capacitor, a solid electrolytic capacitor, a multilayer ceramic capacitor, a film capacitor, a mylar capacitor, or the like can be used. Capacitors with high temperature dependence (for example, multilayer ceramic capacitors) are preferable because they have a large capacitance change rate and can widen the resonance frequency range to be controlled, and capacitors with low temperature dependence (for example, mylar capacitors). It is preferable that the rate of change in capacitance is small and the resonance frequency range can be precisely controlled.

  A temperature controller for heating or cooling the capacitor is connected to the capacitor used in the present invention. The capacitor and the temperature control unit may be manufactured as a single unit, or the temperature control unit may be mounted on an existing capacitor. For example, a commercially available water-cooled condenser or a condenser provided with a temperature controller as described in Patent Document 2 can be used.

  There are no particular restrictions on the heating / cooling method in the temperature control unit, but there are, for example, a method using a Peltier element, a method using a heating element based on electrical resistance, and a method using a gas or liquid heat medium, and a combination of these methods. It may be used. In particular, a method of using water as a heat medium is preferable because it is simple and inexpensive, and a commercially available water-cooled condenser can also be used.

  In the present invention, when the amount of current is large and the capacitor generates a lot of heat for power use, a water-cooled capacitor can be preferably used. In the case of a water-cooled capacitor, the above-described resonance frequency can be controlled by controlling the temperature and flow rate of the coolant. The cooling liquid can be used without particular limitation as long as it is a liquid heat medium. As the cooling liquid, water can be preferably used from the viewpoint of characteristics such as heat capacity and viscosity and cost.

  When controlling the temperature of the cooling water, the temperature may be controlled by raising or lowering the temperature of the water, or hot water and cold water having a constant temperature may be prepared and mixed. These waters may be discharged out of the system or circulated.

  In the present invention, in order to adjust the frequency of the resonance circuit, the resonance frequency of the resonance circuit is detected and fed back to the temperature control unit.

  The method of detecting the resonance frequency is not particularly limited, and examples include a method of detecting from the voltage current and resistance value of the resonance circuit and a method of detecting from the reflected power.

  When the feedback uses a region where the temperature characteristic of the capacitor is positive (a region where the capacitance increases as the temperature rises), the resonance frequency can be increased by controlling the capacitor temperature to be decreased, and the resonance frequency can be decreased. May be controlled to increase the temperature of the capacitor. Further, if a region where the temperature characteristic of the capacitor is negative is used, the control may be performed in the reverse manner.

The resonance circuit of the present invention can be preferably used particularly for a high-frequency power circuit.

Claims (2)

A resonant circuit including a capacitor,
Including a temperature control to heat or cool the capacitor;
The resonance frequency of the resonance circuit is detected and fed back to the temperature control unit.
A resonance circuit, wherein a resonance frequency is controlled by changing a capacitance by controlling a temperature of a capacitor. 2. The resonance circuit according to claim 1, wherein the capacitor is a liquid-cooled capacitor, and the temperature or flow rate of the coolant flowing through the liquid-cooled capacitor is adjusted to control the temperature of the capacitor.