Modular DC power supply with independent output converters

Abstract

A power supply with a DC-DC converter and a switching converter comprises an intermediate circuit and at least one output switching regulator. The intermediate circuit has an intermediate circuit voltage, and is connected to a supply voltage via the DC-DC converter. The at least one output switching regulator is connected to the intermediate circuit, and configured to supply, on the output side, a regulated output voltage.

Claims

1. A power supply, comprising: a DC-DC converter; an intermediate circuit with an intermediate circuit voltage, the intermediate circuit being connected to a supply voltage via the DC-DC converter; at least two output switching regulators connected to the intermediate circuit, each of said at least two output switching regulators supplying, on an output side, a respective regulated output voltage; and a control unit shared by a plurality of the at least two output switching regulators, the control unit only controlling the at least two output switching regulators; wherein as a parameter the control unit is supplied with an instantaneous load of the DC-DC converter; wherein the control unit controls the at least two output switching regulators dependent on said parameter to prevent an overload of the DC-DC converter; and wherein the at least two output switching regulators are deactivated based on a prioritization in an event of imminent overloading of the DC-DC converter and depending on respective connected loads to ensure continuous supply to essential output switching regulators and the respective connected loads.

2. The power supply of claim 1, wherein the DC-DC converter is controlled using a controller, and wherein the controller is supplied with a measured value of the instantaneous intermediate circuit voltage to limit the intermediate circuit voltage to a predefined lower value and to a predefined upper value.

3. The power supply of claim 1, wherein the at least two output switching regulators include a respective current regulator which limits an output current to an adjustable maximum value.

4. The power supply of claim 1, wherein the at least two output switching regulators are supplied with a switch-off signal that causes the at least two output switching regulators to switch off with a time lag after a predefined output current limit value has been exceeded.

5. The power supply of claim 4, wherein the at least two output switching regulators are connected to a timer which outputs the switch-off signal if a predefined output current limit value is exceeded for a predefined period.

6. The power supply of claim 4, further comprising: a temperature sensor for detecting a critical temperature; wherein the switch-off signal is output if a predefined output current limit value is exceeded and if the critical temperature reaches a limit value.

7. The power supply of claim 1, wherein the intermediate circuit voltage is set as a reduced voltage.

8. The power supply of claim 1, wherein the DC-DC converter is constructed as a resonant converter.

9. The power supply of claim 1, wherein a power factor correction circuit is connected upstream of the DC-DC converter for connection to a supply network.

10. The power supply of claim 1, wherein the at least two output switching regulators are connected to the intermediate circuit.

11. The power supply of claim 10, wherein the at least two output switching regulators have one of a shared output voltage regulation and a separate voltage regulation.

12. The power supply of 33, wherein each of the at least two output switching regulators has a separate output voltage regulation with different desired output voltages.

13. The power supply of claim 1, wherein the control unit shared by a plurality of the at least two output switching regulators includes an interface for communication with a bus system to send reporting data and/or receive control data.

14. The power supply of claim 1, further comprising: a basic device with a housing; wherein the housing includes contacts to which the intermediate circuit voltage is applied such that an expansion module with at least one further output switching regulator is connectable to the basic device via said contacts.

15. The power supply of claim 14, wherein the basic device further includes a separate control unit; wherein an interface is provided on the housing of the basic device.

16. The power supply of claim 1, wherein each of the at least two output switching regulator is constructed as a step-down switching regulator.

17. A method for operating a power supply of claim 1, comprising: specifying an upper value and a lower value for the intermediate circuit voltage to a controller for controlling the DC-DC converter; and specifying a desired output voltage value to a controller for controlling the at least one output switching regulator.

18. The method of claim 17, wherein an output current limit value is specified to the at least one output switching regulator, and wherein, in the case of an output current value greater than the output current limit value, the output current is limited to this maximum output current limit value.

19. The method of claim 17, wherein an excess current limit value is specified to the at least one output switching regulator, wherein the excess current limit value is a multiple of the output current limit value, and wherein, before a limitation to the output current limit value in an event the excess current limit value is reached, the output current is limited to the excess current limit value until a critical temperature inside the power supply reaches a limit value or until a predefined period has elapsed.

20. The method of claim 18, wherein the at least two output switching regulators are switched off after a given period in limiting operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be described below using examples and with reference to the accompanying figures, in which schematically:

(2) FIG. 1 shows a power supply according to the prior art;

(3) FIG. 2 shows a power supply with an inventive topology in accordance with one embodiment of the present invention; and

(4) FIG. 3 shows a power supply with basic device and expansion module in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

(5) A conventional power supply has a step-down switching regulator 1 which is connected, by way of example, to a three-phase supply network L1, L2, L3 (FIG. 1). An intermediate circuit 3 with an intermediate circuit resonator is provided at the output of the step-down switching regulator 1. A DC-DC converter 2 then converts an intermediate circuit voltage into an output voltage. The output voltage is regulated using step-down switching regulators 1 because the DC-DC converter 2 has a fixed transmission ratio. The intermediate circuit voltage is therefore fixed at a certain value which depends on the desired output voltage and transmission ratio of the DC-DC converter.

(6) By contrast, according to the invention, an intermediate circuit 3 without fixed intermediate circuit voltage is provided (FIG. 2). Applied to an intermediate circuit capacitor is a voltage which is produced from the power supplied at the input side and removed at the output side. At the input side, power is loaded from the supply network L1, L2, L3 into the intermediate circuit 3 using a DC-DC converter 2. Four output switching regulators 11, 12, 13, 1n, by way of example, are applied to the intermediate circuit 3, and these take power from the intermediate circuit 3 and pass it to connected loads. The DC-DC converter 2 is constructed, for example, as an LLC resonant converter.

(7) Upper and lower limit values for the intermediate circuit voltage are optionally specified to a controller of the DC-DC converter 2 and it is also supplied with a measured value of the instantaneous intermediate circuit voltage. A voltage regulator of the intermediate circuit 3 then intervenes as soon as the intermediate circuit voltage reaches a limit value.

(8) Each output switching regulator is advantageously constructed as a step-down switching regulator. Step-down switching regulators are highly efficient in particular if the level differences between input and output voltage differ only slightly, by way of example, by only a factor of two. With an output voltage conventional in the industrial sector of 24 volts, the intermediate circuit voltage advantageously ranges between 30 and 60 volts.

(9) The topology allows independent adjustment of the voltage and the maximum current at each output. In the event of a disruption, each step-down switching regulator 11, 12, 13, 1n limits the current to the maximum value without the other outputs being affected thereby. The other load paths are continuously supplied despite a faulty load path.

(10) In many applications, the situation can occur where the power removed from the supplied loads is enduringly lower than the available total output of the power supply. Different loads are connected to two outputs by way of example, and these are never active at the same time. The power that can be transferred from the DC-DC converter 2 can then be used by an expansion module B, as illustrated in FIG. 3.

(11) A basic device A includes the DC-DC converter 2 which is connected for example by a power factor correction (PFC) circuit 5 to a single-phase supply network Net. At the output side, the DC-DC converter 2 is connected to four output switching regulators 11, 12, 13, 1n of the basic device A. The output switching regulators 11, 12, 13, 1n are controlled using a control unit SA which is set up as a master. This control unit SA is optionally connected by a suitable interface 4 to external components. A connection to a PROFINET, for example, is provided. Each output switching regulator 11, 12, 13, 1n supplies a regulated output voltage Out.sub.1, Out.sub.2, Out.sub.3, Out.sub.n at its output.

(12) The intermediate circuit 3 and the control unit SA have contacts to which the expansion module B is connected. The expansion module B includes four further output switching regulators 14, 15, 16, 1m which are connected to a shared controller SB. A regulated output voltage Out.sub.4, Out.sub.5, Out.sub.6, Out.sub.m is applied to each output switching regulator 14, 15, 16, 1m.

(13) The control unit SB of the expansion module B is set up as a slave and communicates with the control unit SA of the basic device A. The master control unit SA in the basic device A takes on load management. Scenarios for switching-off processes are provided by way of example if the sum of the power taken from the output switching regulators 11, 12, 13, 1n, 14, 15, 16, 1m exceeds the power of the DC-DC converter 2. In some embodiment, communication between the control unit SA of the basic device A and the control unit SB of an expansion module B can be omitted.

(14) In some embodiments, the intermediate circuit 3 is connected to a further supply. For this purpose, either the intermediate circuit 3 is directly connected to a connectable power source, or a further DC-DC converter is arranged for connection to a further supply source, for example, in a separate connectable module. Connection to an additional supply does not pose a problem especially if the intermediate circuit voltage is designed as an extra-low voltage.

(15) Although the present invention has been described above with reference to presently preferred embodiments, it is not limited thereto but rather can be modified in a wide variety of ways. In particular, the invention can be altered or modified in multifarious ways without departing from the essence of the invention.