Synchronous rectifier, use of such a synchronous rectifier in a switching power supply, as well as a switching power supply

• US 9,692,318 B2
• Filed: 04/22/2014
• Issued: 06/27/2017
• Est. Priority Date: 05/14/2013
• Status: Active Grant

• Current Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Original Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Inventors: Paul, Tobias, Donkers, Niels, Alonso-Schonlau, Juan Angel, Ruf, Klaus
• Primary Examiner(s): Nguyen, Matthew
• Assistant Examiner(s): Ahmed, Yusef
• Application Number:
  US14/890,669
• Publication Number:
  US 20160094146A1
• Time in Patent Office: 1,162 Days
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/10 Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from ac or dc
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H02M 7/217 using semiconductor devices only
• CPC Class Codes: H02M 7/2176 comprising a passive stage to generate a rectified sinusoidal voltage and a controlled switching element in series between such stage and the output
• CPC Class Codes: H02M 7/219 in a bridge configuration
• CPC Class Codes: H02M 7/2195 the switches being synchronously commutated at the same frequency of the AC input voltage
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A synchronous rectifier, which rectifies an alternating voltage signal as an input signal and/or forwards a dc voltage signal as an input signal for use as an output signal. Included is a rectifying unit composed of at least one controllable switch element; a smoothing unit, which is connected to the rectifying unit and smooths the signal rectified or forwarded by the rectifying unit, in order to provide a smoothed signal for use as output signal; a control logic, which controls the rectifying unit based on the input signal and the output signal coming from the smoothing unit.

Claims

1. A synchronous rectifier, which rectifies an alternating voltage signal as an input signal, to an output signal and/or forwards a dc voltage signal as an input signal for use as an output signal, at least comprising:

a rectifying unit composed of at least one controllable switch element;

a smoothing unit, which is connected to said rectifying unit and smooths the signal rectified or forwarded by said rectifying unit, in order to provide a smoothed signal for use as an output signal; and

a control logic, which controls said rectifying unit based on the input signal and the output signal coining from said smoothing unit, wherein;

said control logic includes a digital logic unit, which by means of at least one control signal operates said at least one controllable switch element of said rectifying unit;

said control logic includes a zero point detection unit and a comparison unit;

said zero point detection unit registers zero crossings of the input signal and derives therefrom a first auxiliary signal; and

said comparison unit compares the input signal with the output signal and derives therefrom a second auxiliary signal.

2. The synchronous rectifier as claimed in claim 1, further comprising:

an overvoltage protection unit, which is arranged between said rectifying unit and said smoothing unit and limits the signal rectified by said rectifying unit to a certain turn off threshold.

3. The synchronous rectifier as claimed in claim 2, wherein:

said turn off threshold is changeable.

4. The synchronous rectifier as claimed in claim 1, wherein:

said digital logic unit based on the first and the second auxiliary signal produces said at least one control signal for operating said at one controllable switch element of said rectifying unit.

5. The synchronous rectifier as claimed in claim 1, wherein:

the first and second auxiliary signals and the control signal are digital signals.

6. The synchronous rectifier as claimed in claim 1, wherein:

said at least one controllable switch element is a semiconductor.

7. A switching power supply comprising the synchronous rectifier as claimed in claim 1, wherein:

the synchronous rectifier is arranged on a primary side and receives said input signal of the switching power supply and supplies said output signal to a subsequent direct voltage converter;

the direct voltage converter forms a galvanic isolation between the primary side and a secondary side and the switching power supply has no control loop between the primary side and the secondary side.

8. A switching power supply for energy supply of a load, wherein the switching power supply has a primary side and a secondary side, said primary side has at least one synchronous rectifier, which rectifies an alternating voltage signal as an input signal to an output signal and/or forwards a dc voltage signal as an input signal for use as an output signal, said at least one synchronous rectifier comprising:

a rectifying unit composed of at least one controllable switch element;

a smoothing unit, which is connected to said rectifying unit and smooths the signal rectified or forwarded by said rectifying unit, in order to provide a smoothed signal for use as an output signal; and

a control logic, which controls said rectifying unit based on the input signal and the output signal coming from said smoothing unit, and which receives the input signal and supplies an output signal to a subsequent direct voltage converter, which forms a galvanic isolation between the primary side and the secondary side, wherein;

said control logic includes a digital logic unit, which by means of at least one control signal operates said at least one controllable switch element of said rectifying unit;

said control logic includes a zero point detection unit and a comparison unit;

said zero point detection unit registers zero crossings of the input signal and derives therefrom a first auxiliary signal; and

said comparison unit compares the input signal with the output signal and derives therefrom a second auxiliary signal; and

the switching power supply has no control loop between the primary side and the secondary side.