Switched-mode power supply for powering a frequency converter

• US 9,923,452 B2
• Filed: 04/05/2016
• Issued: 03/20/2018
• Est. Priority Date: 04/23/2015
• Status: Active Grant

• Current Assignee: Dr. Johannes Heidenhain GmbH
• Original Assignee: Dr. Johannes Heidenhain GmbH
• Inventors: Heinrich, Simon, von Le Suire, Christian
• Primary Examiner(s): Dole, Timothy J
• Assistant Examiner(s): Kyaw, Htet Z
• Application Number:
  US15/090,630
• Publication Number:
  US 20160315546A1
• Time in Patent Office: 714 Days
• Field of Search: 363 16, 363 39, 363 2107, 363 2108, 363 49, 363 97, 320166
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H02M 3/3353 having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter

Abstract

A switched-mode power supply for supplying an operating voltage to a frequency converter includes a supply capacitor configured to supply the operating voltage to a control device for generating control signals for semiconductor switches of the switched-mode power supply. The supply capacitor is chargeable through a start-up circuit from a DC link of the frequency converter. The start-up circuit includes a current regulator that is configured to control a total current from the DC link to the start-up circuit.

Claims

1. A switched-mode power supply for supplying an operating voltage to a frequency-converter, the switched-mode power supply comprising:

a supply capacitor configured to supply the operating voltage to a control device for generating control signals for semiconductor switches of the switched-mode power supply; and

a start-up circuit from a DC link of the frequency converter by which the supply capacitor is chargeable, the start-up circuit including a current regulator that is configured to maintain a constant total current from the DC link to the start-up circuit, wherein a valve of the current regulator that controls the total current is configured to act only on a first partial current which, together with a second partial current, makes up the total current, the second partial current including a leakage current of the control device and a charging current of the supply capacitor, wherein none of the first partial current acted on by the valve flows to the control device.

2. The switched-mode power supply as recited in claim 1, further comprising two DC link capacitors connected in series in the DC link and configured to provide a mid-potential between an upper and a lower potential of the DC link, the supply capacitor having two terminals and being connected, at each of the two terminals, to a respective one of the upper and lower potentials of the DC link through a respective high-resistance resistor chain so that the start-up circuit and the control device are at the mid-potential.

3. The switched-mode power supply as recited in claim 2, wherein the control device is galvanically isolated from the semiconductor switches by gate driver transformers.

4. The switched-mode power supply as recited in claim 2, wherein a first terminal of a primary winding is connected to the mid-potential, and a second terminal of the primary winding is switchable between the upper and lower potentials of the DC link by means of the semiconductor switches.

5. The switched-mode power supply as recited in claim 1, further comprising, on a secondary side, a secondary winding and a self-supply winding whose rectified output voltages are buffered by a respective first and second buffer capacitor and fed to a voltage regulator which allows the control device to be supplied with the operating voltage during operation of the switched-mode power supply.

6. The switched-mode power supply as recited in claim 5, wherein the first buffer capacitor of the secondary winding has a capacitance that is a factor of at least 1,000 higher than that of the second buffer capacitor of the self-supply winding.

7. The switched-mode power supply as recited in claim 6, wherein the first buffer capacitor is isolated by a diode from the second buffer capacitor.