Insulating-type switching electric power source device

• US 6,597,588 B2
• Filed: 08/06/2002
• Issued: 07/22/2003
• Est. Priority Date: 08/10/2001
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Matsumoto, Tadahiko
• Primary Examiner(s): Vu, Bao Q.
• Application Number:
  US10/212,262
• Publication Number:
  US 20030035306A1
• Time in Patent Office: 350 Days
• Field of Search: 363/21.08, 363/21.16, 323/907
• US Class Current: 363/21.08
• CPC Class Codes: H02M 1/0019 the disturbance parameters being load current fluctuations
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: Y10S 323/907 Temperature compensation of semiconductor

Abstract

An insulating-type switching electric power source device has an input voltage Vin of a primary side that is converted at an input/output ratio determined by switching operations of a switching device, and then is output. Voltage subjected to rectifying and smoothing by a primary-side rectification smoothing circuit is used as detecting signals of the output voltage, to control the time ratio of the switching device. A load regulation correcting circuit outputs load regulation correcting signals correlated with the amount of output current. A temperature compensating circuit corrects the load regulation correcting signals according to the ambient temperature. The load regulation correcting signals correct the output voltage detecting signals according to the fluctuations of the output voltage according to fluctuations in the output current and fluctuations in the ambient temperature. As a result, fluctuations in the output voltage caused by fluctuations in the output current and fluctuations in the ambient temperature are compensated for.

Claims

1. An insulating-type switching electric power source device, comprising:

a transformer having a primary side and a secondary side;

a switch device provided at the primary side of said transformer and converting input voltage of the primary side of said transformer to output voltage of the secondary side of said transformer;

a primary side rectification smoothing circuit provided at the primary side of said transformer and performing rectification smoothing of the voltage of a coil of said transformer;

a control circuit for using said voltage subjected to rectification smoothing as detection signals of output voltage, and controlling the time ratio of said switch device so as to stabilize said output voltage;

a load regulation correcting circuit detecting current correlated with output current by a current detecting device provided in a circuit at the primary side, the load regulation correcting circuit generating load regulation correcting signals having a correlation with said output current from the detected current and correcting detection signals of said output voltage, according to output voltage fluctuations due to output current fluctuations; and

a temperature compensating circuit for changing the amount of load regulation correction by said load regulation correcting circuit according to the fluctuations in the ambient temperature, so as to reduce the amount of load regulation correction under low-temperature environments, and to increase the amount of load regulation correction under high-temperature environments.

2. An insulating-type switching electric power source device according to claim 1, further comprising a secondary-side rectification smoothing circuit for performing rectification smoothing of the voltage of a secondary coil of said transformer, wherein said secondary-side rectification smoothing circuit includes a MOS-FET which is a synchronous rectifier.

3. An insulating-type switching electric power source device according to claim 1, wherein said load regulation correcting circuit includes:

a switching current detecting device detecting switching current and defining said current detecting device; and

a capacitor to which the voltage of said switching current detecting device is peak-charged;

whereby said load regulation correcting circuit outputs the charged voltage of said capacitor as load regulation correcting signals.

4. An insulating-type switching electric power source device according to claim 1, wherein said temperature compensating circuit includes:

a serial resistor connection unit including a plurality of resistors introduced in a conducting path of said load regulation correcting circuit for generating load regulation correcting signals; and

a temperature sensing unit connected in parallel to a position where a divided voltage of said serial resistor connection unit is applied;

wherein said temperature sensing unit is configured such that equivalent resistance values change due to fluctuations in ambient temperature, thereby changing the resistance values of said temperature compensating circuit, thus performing temperature compensation for the load regulation correcting signals passing through said temperature compensating circuit.

5. An insulating-type switching electric power source device according to claim 1, further comprising:

a serial connection unit including a plurality of resistors connected to the output side of said primary-side rectification smoothing circuit, and the divided output voltage from said serial connection unit is output to said control circuit as detection signals of the output voltage of said switching electric power source device;

wherein said temperature compensating circuit includes;

a temperature compensating current channel for supplying current to a voltage dividing position which differs from the detection signal output unit at said serial connection unit of said resistors; and

a temperature sensing unit which is introduced into said temperature compensating current channel and which varies the amount of conduction on said temperature compensating current channel according to fluctuations in the ambient temperature;

said temperature compensating circuit changes detecting signals applied to said control circuit from said primary-side rectification smoothing circuit according to temperature change, by fluctuating the amount of current supplied to the serial connecting unit of said resistors from said temperature compensating current channel with said temperature sensing unit so as to change the voltage dividing ratio of said serial connecting unit of said resistors, thereby performing temperature compensation for load regulation correction.

6. A switching electric power source device, comprising a plurality of insulating-type switching electric power source devices according to claim 1, wherein the input and output of each of said plurality of insulating-type switching electric power source devices are connected in parallel.