Power Converter

• US 20080259647A1
• Filed: 10/24/2006
• Published: 10/23/2008
• Est. Priority Date: 10/25/2005
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Risseeuw, Pieter Martin
• Application Number:
  US12/091,101
• Publication Number:
  US 20080259647A1
• Time in Patent Office: Days
• US Class Current: 363/21.1
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 3/015 with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuit
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/33571 Half-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 7/4818 with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuits
• 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 power converter comprises a series arrangement of a first main current path of a first controllable switch (M2) and a second main current path of a second controllable switch (M3). The series arrangement is arranged to receive a DC-input voltage (V1). A series arrangement of an inductance (L) and a capacitance (2) is arranged in parallel with the second main current path. An output node (NO) which is coupled to the inductance (L) supplies an output voltage (VO) of the power converter. The power converter further comprises a means (M1) for varying the capacitance (2). A controller (1) controls the first controllable switch (M2) and the second controllable switch (M3) with a variable repetition frequency (fr) to stabilize the output voltage (VO), and controls the means (M1) for varying to vary the capacitance (2) or the inductance (L) in dependence on an output power of the power converter.

Claims

1. A power converter comprising

a series arrangement of a first main current path of a first controllable switch (M2) and a second main current path of a second controllable switch (M3), the series arrangement being arranged for receiving a DC-input voltage (V1),

a series arrangement of an inductance (L) and a capacitance (2) being arranged in parallel with the second main current path, wherein the inductance (L) and capacitance (2) determine a resonance frequency (fr1, fr2),

an output node (NO) coupled to the inductance (L) for supplying an output voltage (VO) of the power converter,

a means (M1) for varying the capacitance (2) or the inductance (L), and

a controller (1) for controlling the first controllable switch (M2) and the second controllable switch (M3) with a variable repetition frequency (fr) to stabilize the output voltage (VO), and for controlling the means (M1) for varying to vary the capacitance (2) or the inductance (L) in dependence on a required peak output power of the power converter.

2. A power converter as claimed in claim 1, wherein:

the capacitance (2) comprises a first capacitor (C1) and a second capacitor (C2;

C20),

the controller (1) is constructed for supplying a switching signal (CS1), and

the means (M1) for varying comprise a switch (M1) having a control input for receiving the switching signal (CS1) for selectively connecting the second capacitor (C2) in parallel with the first capacitor (C1), or for selectively short circuiting the second capacitor (C20) if arranged in series with the first capacitor (C1).

3. A power converter as claimed in claim 1, further comprising a rectifier (RE) coupled between the inductor (L1, L2) and the output node (NO) for supplying the output voltage (VO) being a DC-voltage to a load (LO).

4. A power converter as claimed in claim 1, wherein the inductance comprises a primary winding of a transformer, and wherein a load is coupled to a secondary winding of the transformer.

5. A power converter as claimed in claim 1, wherein the controller (1) is arranged for receiving a command (PC) indicating a power mode of a load (LO) being coupled to the output node (NO) to increase the capacitance (2) or the inductance (L) if the command (PC) indicates a power consumption of the load (LO) higher than a predetermined level.

6. A power converter as claimed in claim 5, wherein the load (LO) has a first power mode being a standby mode and a second mode being a normal operating mode, wherein the command (PC) is a standby command, and wherein the capacitance (2) or the inductance (L) has a lower value during the standby mode than during the normal mode.

7. A power converter as claimed in claim 1, wherein the controller (1) comprises a comparator (110) having a first input for receiving the DC-input voltage (V1), a second input for receiving a predetermined level (VR1) and an output for supplying a switching signal (CS1) to the means (M1) for varying to increase the capacitance (2) or the inductance (L) if the DC-input voltage (Vi) drops below the predetermined level (VR1).

8. A power converter as claimed in claim 1, wherein the controller (1) comprises:

a frequency determining circuit (10′

) for generating a frequency signal (RF) indicating the variable repetition frequency (fr), and

a switch control circuit (11′

) for receiving the frequency signal (RF) to supply the switching signal (CS1) for increasing the capacitance (2) or the inductance (L) if the repetition frequency (fr) drops below a predetermined frequency (fr1).

9. A power converter as claimed in claim 1, wherein the controller (1) comprises:

means (10″

) for limiting the repetition frequency (fr) to a predetermined minimal value (fm), and

an error amplifier (12) for receiving a reference signal (VR2) and an input signal (VO′

) being proportional to the output voltage (VO) to supply an error signal (ER) indicating a difference between the input signal (VO′

) and the reference signal (VR2),

a clipping detector (13) for receiving the error signal (ER) to detect a clipping of the error signal (ER), and

a switch control circuit (11″

) for increasing the capacitance (2) if the clipping detector (13) has detected the clipping of the error signal (ER).

10. An apparatus comprising a circuit (LO) operating in different power modes wherein the circuit (LO) consumes different powers, and the power converter as claimed in claim 1, wherein the circuit is coupled to the output node (NO).

11. A method of controlling a power converter comprising a series arrangement of a first main current path of a first controllable switch (M2) and a second main current path of a second controllable switch (M3), the series arrangement being arranged for receiving a DC-input voltage (V1), a series arrangement of an inductance (L) and a capacitance (2) being arranged in parallel with the second main current path, and an output node (NO) coupled to the inductance (L) for supplying an output voltage (VO) of the power converter, and wherein the method comprises controlling (1) the first controllable switch (M2) and the second controllable switch (M3) with a variable repetition frequency (fr) to stabilize the output voltage (VO), and varying (M1) the capacitance (2) or the inductance (L) in dependence on an required peak output power of the power converter.