A.C./D.C. converter having a linearly controllable one-way switch, and using no high voltage passive components

• US 6,246,597 B1
• Filed: 12/17/1999
• Issued: 06/12/2001
• Est. Priority Date: 12/17/1998
• Status: Expired due to Term

• Current Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Peron, Benoît
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US09/466,166
• Time in Patent Office: 543 Days
• Field of Search: 323/303, 363/52, 363/53, 363/54
• US Class Current: 363/54
• CPC Class Codes: H02M 7/1555 with control circuit

Abstract

A converter of a high A.C. voltage into a low D.C. voltage, including a one-way switch between a first terminal of application of the A.C. voltage and a first positive output terminal, and circuitry for controlling the output voltage to a desired value, the one-way switch being controlled in linear mode.

Claims

1. A converter of a high A.C. voltage into a low D.C. voltage, including a one-way switch controlled in linear mode between a first terminal of application of the A.C. voltage and a first positive output terminal, said converter including no high voltage passive components, and comprising means for controlling an output voltage to a desired value,

said control means including:

a first element for setting a reference voltage and comparing this reference voltage with the output voltage;

a second element for setting a reference current; and

first means for modifying a current of linear control of the one-way switch upon closing and opening.

2. The converter of claim 1, wherein the first element generates an error signal only when the output voltage is greater than the reference voltage.

3. The converter of claim 2, wherein the first means is, at a beginning and at an end of each halfwave of an A.C. power supply, activated and deactivated in a vicinity of a zero crossing of the A.C. power supply.

4. The converter of claim 1, wherein the control means further includes a second means for forcing conduction of the one-way switch upon power-on and in case of a microfailure of the A.C. power supply.

5. The converter of claim 4, wherein the second means for managing the microfailures is sized to be activated within an activation range of the first means to linearly modify the control current of the one-way switch.

6. The converter of claim 1, wherein the one-way switch is formed by a rectification means in series with a Darlington-type assembly of bipolar transistors.

7. The converter of claim 6, wherein a diode is connected between a common collector of the bipolar transistors and a base of a last transistor receiving a control signal, to force the transistors to operate in linear mode.

8. The converter of claim 1, associated at its input with a varistor that protects against overvoltages and, preferably, with a resistor of very small value that protects this varistor.

9. A converter of a high A.C. voltage to a low D.C. voltage, including:

a linearly controllable one-way switch disposed between a first terminal of application of the A.C. voltage and a first output terminal of the D.C. voltage;

a control circuit for controlling an output D.C. voltage to a desired value, comprising;

a first element to set a reference voltage and compare the reference voltage with an output voltage;

a second element to set a predetermined reference current according to a current requirement of a load;

a circuit for modifying a current of linear control of the one-way switch upon closing and opening;

a low voltage capacitor to filter the output voltage; and

wherein the converter includes no high voltage passive components.

10. The converter of claim 9, wherein the linearly controllable one way switch includes a plurality of high voltage bipolar transistors.

11. The converter of claim 9, wherein the linearly controllable one-way switch includes a rectifier in series with a Darlington-type assembly of bipolar transistors.

12. The converter of claim 9, wherein the first element generates an error signal when the output voltage is greater than the reference voltage.

13. The converter of claim 9, further including a third element to force conduction of the one-way switch upon power-up and in the event of a microfailure of an A.C. supply voltage.

14. The converter of claim 9, further including:

a varistor associated with an input of the converter, to protect against overvoltages; and

a small-valued resistor to protect the varistor.

15. A converter of a high A.C. voltage to a low D.C. voltage, including:

a linearly controllable one-way switch, controlled by a control current;

a first element for providing a predetermined reference voltage such that when an output voltage exceeds the reference voltage, an error current is generated, said error current being used to adjust the control current;

a second element to damp variations of the control current and determine a variation slope of the control current;

a third element to set a reference current according to a power requirement of a load, the error current, when it occurs, being subtracted from the reference current;

a fourth element to force conduction of the one-way switch upon power-up and in the event of a microfailure of an A.C. power supply.

16. The converter of claim 15, wherein the switch is turned on twice per halfwave of the A.C. voltage for a short duration with respect to a duration of the halfwave and in the vicinity of a zero-crossing of the halfwave.