MULTI-PHASE SWITCHED POWER CONVERTER

Abstract

A multi-phase power converter comprising a plurality of phases for generating an output voltage according to a switching signal and an input voltage, each phase of the plurality of phases comprising a switching element and inductance; wherein the plurality of phases is connected to a common star point, wherein an output capacitor is connected to the common star point. The phases of the multi-phase power converter are not identical in terms of their inductance. Therefore, at least one phase may be optimized for a low current such that, in low power operation, said at least one phase is optimal for lower current levels.

Claims

1. Multi-phase power converter comprising a plurality of phases for generating an output voltage according to a switching signal and an input voltage, each phase of the plurality of phases comprising a switching element and inductance; wherein the plurality of phases is connected to a common star point, wherein an output capacitor is connected to the common star point; and wherein the inductance of at least one phase differs from the inductance of another phase.

2. The multi-phase power converter according to claim 1, wherein the inductance is anti-proportional to a ripple inductor current.

3. The multi-phase power converter according to claim 2, wherein the inductance of the at least one phase is selected such that the ripple operating current is 20%-40% of a peak current.

4. The multi-phase power converter according to claim 1, wherein the inductance of each of the plurality of phases differs from the inductance of another phase.

5. The multi-phase power converter according to claim 1, wherein the switching element of the at least one phase differs from the switching element of another phase.

6. The multi-phase power converter according to claim 1, wherein the switching element of the at least one phase is optimized for an operating current of said phase.

7. The multi-phase power converter according to claim 5, wherein the switching element is a dual switching element.

8. The multi-phase power converter according to claim 1, wherein the switching element of each of the plurality of phases differs from the inductance of another phase.

9. The multi-phase power converter according to claim 1 being a buck-converter.

10. The multi-phase power converter according to claim 1 being a boost-converter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Reference will be made to the accompanying drawings, wherein:

[0013] FIG. 1 shows a block-diagram of multi-phase power converter.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The multi-phase power converter shown in FIG. 1 comprises three phases controlled by switching signals Vg1, Vg2, Vg 3 for generating an output current or voltage according to input voltage Vin and the switching signals.

[0015] The first phase comprises a dual switching element comprising an inverter U1 a high-side field effect transistor (FET) Q1 and a low-side FET Q2, and an inductance L1. The second phase comprises a dual switching element comprising an inverter U2 a high-side FET Q3 and a low-side FET Q4, and an inductance L2. The third phase comprises a dual switching element comprising an inverter U3 a high-side FET Q5 and a low-side FET Q6, and an inductance L3.

[0016] The three phases are connected to a common star point to which the capacitor C1 is connected to. Each phase produces its own operating current for charging the capacitor C1.

[0017] While in the prior art the inductance L1, L2 and L3 are equal and the FETs Q1, Q2, Q3, Q4, Q5 and Q6 are identical, according to the present invention the inductance of at least one phase differs from the inductance of another phase. At least one phase may be optimized for a low current such that, in low power operation, said at least one phase is optimal for lower current levels.

[0018] For example, the third phase may be optimized for lower current levels. L1 equals L2, but L3 differs from L1 and L2.

[0019] Optimally, the inductance L3 may be selected such that the ripple current is 20%-40% of the peak current value. For fixed input and output voltage, to first order, the ripple current is proportional to the inverse of the inductance.

[0020] Moreover, the dual switching elements may be optimized for each phase since an optimal switching device selection depends on the operating current of that phase. Switching elements Q5 and Q6 may be optimized with respect to their size and cost for example, for the operating current of the third phase. Q1 may be identical to Q3, but Q5 may be different from Q1 and Q3. Q2 may be identical to Q4, but Q6 may be different from Q2 and Q4.

[0021] The inductance of each of the plurality of phases may be different from the inductance of another phase. Hence, each phase may be optimized for its individual operating current.

[0022] Also, the switching element of each of the plurality of phases may be different from the inductance of another phase.

[0023] The three-phase buck converter is just an example. The concept of optimized inductances and switching elements for the load conditions of an individual phase may be applied to any buck or boost converter design.