Power source circuit with a compact size and operating efficiently at low temperature
AssigneeKabushiki Kaisha Toshiba
InventorHiroshi Miyazaki
Life of this patent
Estimating the term…
Abstract
A power source circuit converts direct: current (DC) power into alternating current (AC) power having a required frequency, and provides DC output power according to the AC power. The power source circuit comprises an oscillator for providing a control signal that determines a converting frequency of the AC power; an element provided for the oscillator, having temperature characteristics for increasing the converting frequency at a low temperature; and a device for determining the converting frequency of the AC power according to the control signal provided by the oscillator.
Claims19
A power source circuit for converting direct current (DC) power into alternating current (AC) power having a required frequency and providing DC output power according to the AC power for use upon a change of ambient temperature, comprising:
- oscillation means for providing a control signal that determines a converting frequency of the AC power;
- sensing means for said oscillation means, having temperature characteristics for increasing the converting frequency upon changing of ambient temperature;
- determination means for determining the converting frequency of the AC power based on said control signal provided by said oscillation means;
- a transformer coupled to said determination means;
- and
- DC output detection means, including a temperature sensor, for temperature-dependently detecting the DC output power.
A driving circuit for driving a motor for use upon a change of ambient temperature, comprising:
- oscillation means for providing a control signal that determines a converting frequency of AC power;
- sensing means provided for said oscillation means, having temperature characteristics for adjusting the converting frequency upon a change of ambient temperature;
- determination means for determining the converting frequency of the AC power based on the control signal provided by said oscillation means;
- a transformer coupled to said determination means;
- and
- means connected to a secondary winding of said transformer for providing DC output power to said motor.
A power source circuit for driving a load having temperature dependency with power supplied through power transformer means and limiting the power supplied to the load according to detected values, comprising:
- output current detection means for temperature-dependently detecting an output current supplied to the load;
- output voltage detection means for temperature-dependently detecting an output voltage supplied to the load;
- input current detection means for temperature-dependently detecting an input current supplied to the power source circuit;
- and
- limit means for limiting the power supplied to the load according to values detected by at least two of said detection means.
A method in a DC power source circuit for providing an output power signal with characteristics that follow the temperature characteristics of a load, comprising the steps of:
- providing a control signal from an oscillator circuit that determines a converting frequency to convert a DC signal to an AC signal according to temperature;
- sensing the temperature with a temperature sensor in the oscillator circuit;
- adjusting the converting frequency according to the sensed temperature;
- sensing an output current according to temperature in a current sensing circuit, the current sensing circuit including a temperature sensor, and providing a sensed current control signal;
- sensing an output voltage according to temperature in a voltage sensing circuit, the voltage sensing circuit including a temperature sensor, and providing a sensed voltage control signal;
- determining the converting frequency of the AC power according to the voltage and current control signals provided to a pulse width modulator circuit;
- and
- outputting the output power signal according to the frequency of the AC power that follows the temperature characteristics of the load.
A power source circuit for driving a load having temperature dependency and limiting power supplied to the load according to a detected value, comprising:
- output current detection means for temperature-dependently detecting an output current supplied to the load, said output current detection means including a thermistor having nonlinear positive temperature characteristics;
- and
- limit means for limiting the power supplied to said load according to said output current detected by said output current detection means.
A power source circuit for driving a load having temperature dependency and limiting power supplied to the load according to a detected value, comprising:
- output voltage detection means for temperature-dependently detecting an output voltage supplied to the load, said output voltage detection means including a thermistor having nonlinear negative temperature characteristics;
- and
- limit means for limiting the power supplied to said load according to said output voltage detected by said output voltage detection means.
A power source circuit for supplying DC power to a load comprising:
- a rectifying circuit receiving an input alternating current (AC) signal and outputting a direct current (DC) signal;
- a converter transformer, to which said DC signal is applied, for converting said DC signal applied to said converter transformer into an AC signal according to a frequency at which said applied DC power is switched ON and OFF;
- a control circuit including an oscillation circuit and a pulse width modulation (PWM) controller providing a control signal to switch ON and OFF said DC power applied to said transformer thereby controlling a converting frequency of said AC power;
- means for detecting a change in ambient temperature and for providing said control circuit an indication of said change, said control circuit thereby adjusting said converting frequency according to said change;
- and
- means connected to a secondary winding of said converter transformer for providing DC output power to said load.
Dependencies are inferred from the claim text.