WO2011100861A1

WO2011100861A1 - Power conversion circuit and method of power conversion

Info

Publication number: WO2011100861A1
Application number: PCT/CN2010/000222
Authority: WO
Inventors: Violet Han
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2010-02-22
Filing date: 2010-02-22
Publication date: 2011-08-25
Anticipated expiration: 2012-08-22

Abstract

A power conversion circuit (200) is provided. The circuit includes a power module (20) for providing a constant current as a source current; a plurality of switch components (21,22,23), each of which being coupled to the power module; a plurality of capacitors (31,32,33), each of which being coupled to a corresponding switch component in series; and a control module (23), coupled to each of the switch components to control the switch components to switch on or off by monitoring change of the voltage of a branch circuit. The branch circuit (1,2,3) includes the switch component and the corresponding capacitor.

Description

A POWER CONVERSION CIRCUIT AND A METHOD OF POWER CONVERSION

TECHNICAL FIELD

The present invention relates to power converting technology, more particularly, to a power conversion circuit and a method of power conversion.

BACKGROUND

With increasing complexity of electronic systems, it is common for an electronic system to require power provided at several different discrete voltage. For example, electronic systems may include discrete circuits requiring voltage such as 3v, 5v, 9v etc.

To meet this requirement, a power distribution system is employed, which includes an individual point-of-load ("POL") regulator at the point of power consumption within the electric system. Particularly, a POL regulator would be included with each respective electronic circuit to convert the intermediate bus voltage, which derived from an isolated DC/DC converter, into the level required by each of the electronic circuits. Generally, an electronic system includes multiple POL regulators to convert the intermediate bus voltage into each of the multiple voltage levels.

FIG. 1 depicts an existing distributed power system. As shown, an isolate DC/DC converter 10 generates an intermediate bus voltage by changing a nominal input voltage from a bulk AC/DC rectifier module. The intermediate bus voltage is then convened to point-of-load voltages via POLs 11, 12 and 13. And the POLs 11, 12 and 13 convert the intermediate bus voltage into the level required by the electronic circuits respectively.

With this distributed approach, multiple POLs are configured in the electronic systems, thus the space of the electronic system becomes larger and the cost is higher. Moreover, implementation of many POLs and power manage circuit cause debugging to be difficult, especially when it comes to electromagnetic issues as every POL is playing as an

electromagnetic source in the electrical system.

Thus, it would be advantageous to have a power conversion circuit and method which can not only satisfy the requirement of different voltage for the respective circuit, but also drawbacks above mentioned.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a power conversion circuit, including:

a power module for providing a constant current as source current ;

a plurality of branch circuits, each of which being coupled to the power module, and each branch circuit at least including a switch component and a capacitor coupled to the switch component in series; and

a control module, connected to each of the branch circuits via being coupled to the switch component of each of the branch circuits to control the switch component to switch on by monitoring change of the voltage of each branch circuits.

According to another aspect of the present invention, there is provided a device with the power conversion circuit.

According to yet another aspect of the present invention, there is provided a method of power conversion, the method including :

providing a constant current as source current by a power module ;

monitoring change of the voltage of each of branch circuits by a control module;

delivering the source current to any of the branch circuits by means of the control module switching on a switch component of the branch circuit according to the monitored change; and converting the voltage of the branch circuit by means of charging a capacitor based on the delivered current, wherein the capacitor is set in the branch circuit and coupled to the switch component.

Various other aspect and features of the present invention are defined in the claims. The above and other objects, features and advantages of this invention will be apparent from the following detailed description of illustrative embodiments which is to be read in connection with the accompanying drawings .

BRIEF DESCRIPTION OF THE DRAWINGS

FIG.l depicts an existing distributed power system; FIG .2 is a schematic diagram of the power conversion circuit according to the present invention;

FIG.3 is an exemplary configuration of the control module according to the present invention;

FIG.4 is an example of the control scheme according to the present invention;

FIG.5 is a flow chart of the method of power conversion according to the present invention; and

FIGs.6-9 show different example of the simulation result respectively, according to the present invention.

DETAILED DESCRIPTION

The present invention provides a power conversion circuit and method for monitoring and controlling the adjustment of the voltage of each branch circuit. In the detailed description that follows, like element numerals are used to describe like elements illustrated in one or more figures.

Referring first to FIG .2, a power conversion circuit 200 is shown in accordance with the present invention. The power conversion circuit 200 includes a power module 20, a plurality of switch components 21, 22 and 23, a plurality of capacitors 31, 32 and 33, and a control module 23. The power module 20, which provides a constant current I as source current, here depicted is, but not limited to, an isolated constant current source, and the other power source or power device which can provide a constant current source also can be used. The power module 20 is connected to the branch circuits 1, 2 and 3 via the switch components 21, 22 and 23, respectively. Each of the plurality of the capacitors 31, 32 and 33 is provided to increase the voltage applied to the corresponding load which is coupled to the capacitor in parallel. The control module 23, which is coupled to the switch components and connected to the branch circuits, is employed to monitor the change of the voltage of each branch circuits. The control module 23 is further utilized to control the corresponding switch component to switch on or off based on the detected change, when the control time is distributed to the branch circuit in accordance with a control scheme, where the control time means the period of time during which the control module handles the detected change. The power module 23 which can be implemented by a Digital Signal Processor (DSP) or Field Programmable Gate Array (FPGA) is programmable. The power module 23 further can be implemented by means of the hardware, the software or the combination of the hardware and software .

As an example, each of the switch components 21, 22 and 23 can be MOSFET, which is coupled to the power module 20 at its source node, coupled to the respective capacitor at its drain node, and couples to the control module 23 at its gate node. Alternatively, the MOSFET also can be coupled to the power module 20 at its drain node, and coupled to the capacitor at its source node, and in this case, a diode can be connected between the MOSFET and the capacitor. It should be noted that the MOSFET is only used as an example, not as a limitation, any other active switch component , such as IGBT etc . , can be employed . Term ''active switch component" herein can be any type of component which serves as switch with the ability to electrically control electron flow. FIG. 3 is an exemplary configuration of the control module 23 according to the present invention. As shown in FIG. 3, the control module 23 includes a detecting unit 230, a timing logic unit 231, a power supply unit 232 and a process unit 233. The control module 23 monitors the change on voltage of each branch circuit through detecting the voltage by the detecting unit 230. The timing logic unit 231 generates a control scheme for the branch circuits, the control scheme being programmable according to the control mechanism required by the user. The power supply unit 232 feeds power supply to the switch component 21, 22 and 23. In the case of the MOSFET is employed as the switch component, the power supply unit 232 feeds power to the MOSFET at its gate node .

FIG. 4 is an example of control scheme according to the present invention . The timing logic unit 231 of the control module

23 produces the control scheme relative to a reference tag 40.

In the present embodiment, the time sequence 41 is applied to the branch circuit 1, the time sequence 42 is applied to the branch circuit 2, and the time sequence 43 is applied to the branch circuit 3. As shown in FIG. 4, the time sequence 41 firstly changes to high level from low level at the first rising edge of the reference tag 40 and subsequently changes to low after one period of the reference tag 40, wherein the duty cycle of the time sequence 41 is 2/7; the time sequence 42 changes to high level from low level at the second rising edge of the reference tag 40 and subsequently changes to low after two periods of the reference tag 40, and the duty cycle of the time sequence 42 is 4/7; and the time sequence 43 changes to high level from low level at the fourth rising edge of the reference tag 40 and changes to low after 1/2 period of the reference tag 40, wherein the duty cycle of the time sequence 43 is 1/7. In other words, the time sequence 42 rises to high level at the falling edge of the time sequence 41, and the time sequence 43 rises to high level at the falling edge of the time sequence 42, moreover, the time sequences 41, 42 and 43 has the same period.

Now with reference to Figures 2, 3 and 4 , when the detecting unit 230 detects that the voltage Voi of the branch circuit 1 is less than a pre-set voltage for the branch circuit 1, and at the same time, the time sequence 41 is at high level, then the process unit 233 communicates a switch-on signal to the power supply unit 232 to change the state of the power supply, e.g., switch on the power supply to the gate node of the MOSFET. In this case, the current I from the power module 20 passes through the switch component 21 to the branch circuit 1. With the current being delivered to the branch circuit 1, the capacitor 31 is charged . Accordingly, the voltage V₀i of the branch circuit, i.e. , the voltage across the load, is increased. The pre-set voltage which is pre-set for each branch circuit can be programmed by the user.

In the event of at least two branch circuits are detected that the voltages are less than the respective pre-set voltage, which one of the switch components should be switched on depends upon the control scheme. For example, the branch circuits 1 and 3 both are detected the changes on the voltage by the control module 23, in which the detected voltage is less than the pre-set voltage respectively, and the control module 23 is aware of that the time sequence 43 is at a high level 430 and the time sequence 41 is at low level 410 by checking the control scheme, in this way, the control module 23 only switches on the switch component 23.

As above described, when one of the switch components is switched on, the current I from the isolated power module 20 is delivered to the branch circuit which includes the switch component, the voltage of the capacitor set in the branch circuit can be obtained from equation: Wherein the current I is the constant current from the power module 20, C represents the capacitance of the capacitor, Vo represents the voltage across the capacitor, and t is the charging time .

Since the current I has a constant value, the voltage Vo across the capacitor, namely the voltage of the branch circuit, is linear with the charging time t.

Accordingly the voltage V₀ can be controlled by means of adjusting the charging time by the control module 23, where the charging time t can be set via the control scheme by the control module 23, for example, the charging time t can be set in manner of software through the control module 23 by the user.

In addition, each of the capacitors can be a super capacitor and has a capacitance of such as IF etc.

Although the power conversion circuit is described with reference FIGs . 2 , 3 and 4, it will be appreciated that, the number of the switch component, the capacitor and the branch circuit shown above is only used to be an example, not to limit the number of these elements.

FIG. 5 is a flow chart of the method of power conversion according to the present, invention. As shown in FIG. 5, pre-set (step 50) plurality of voltages for branch circuits via for example a control module, wherein each pre-set voltage corresponds to one branch circuit. And a power module, such as an isolated constant current source, provides (step 51) a constant current as source current to the branch circuits. Then a control module monitors (step 52) whether the voltage of each branch circuit is less than the respective pre-set voltage by means of detecting the voltage of the branch circuit. If the detected voltage is less than the pre-set voltage, then the control module checks (step 54) whether the time sequence for this branch circuit is in the state of high level according to a control scheme, wherein the control scheme is produced through a programmable mechanism by such as the control module. If so, then the source current is delivered (step 56) from the power module to this branch circuit by means of switching on a switch component through which the branch circuit is coupled to the isolated constant current source, wherein the operation of switching on is executed by the control module. Thus the voltage of the branch circuit is converted (step 58) by means of charging a capacitor, which is set in the branch circuit and couple to the switch component, on the basis of the delivered source current.

Now with reference to Figures 2, 3 and 5, the pre-set voltage for each of the branch circuits 1, 2 and 3 can be set through the control module 23 by the user. The detecting unit 230 detects the voltage of each branch circuit, and sends a change signal to the process unit 233 when the detected voltage is less than the pre-set voltage. The process unit 233 then checks the control scheme produced by the timing logic unit 231, and communicates a switch-on signal to the power supply unit 232 when the time sequence is in the state of high level. The power supply unit 232 switches on the switch component according to the switch-on signal. The source current I is thus delivered to the branch circuit, and the capacitor is charged. Accordingly, the voltage of the branch circuit is increased.

FIG. 6 depicts a simulation result according to the present invention. As shown in FIG. 6, when the voltage V₀i of the branch circuit 1 is less than 3.3V and the pulse, namely the time sequence for branch circuit 1, is high, the voltage Voi is increase. As with the adjusting operation of branch circuit 1, the voltage Vo2 of branch circuit 2 and voltage V03 of branch circuit 3 also can be adjusted.

FIG. 7 depicts an example simulation where the voltages of the branch circuits start up at the same slew rate. According to the present invention, each voltage of the branch circuits can be started up at the same slew rate, based on adjusting the control module by means of programming, FIG . 8 depicts another example simulation where the voltage of each branch circuit starts up at same time. As shown in FIG. 8 , the voltage of each branch circuit rises to the required voltage within same time period. FIG. 9 depicts yet another example simulation where each branch circuit starts up in turns.

From described above, according to the present invention, the required control scheme can be set via the control module, and the required pre-set voltage and other control information also can be set by the user in manner of programming, based on the control module 23 being programmed.

It should be appreciated that power conversion circuit and the method of power conversion of the present invention provide certain advantages over prior art distributed power distribution system with POL. The present power conversion circuit converts the voltages of the branch circuits in conjunction with a switch component, a super capacitor and a programmable control module, without a plurality of POL converters or regulators, thereby reducing the amount of the circuit space and easing the debugging, in particular, the likelihood of adjusting the parameters of the power conversion circuit without changing the electric element is much increased.

Having thus described a preferred embodiment of a circuit and method to convert the voltage of the branch circuits, it should be apparent to those skilled in the art that certain advantages of the circuit have been achieved. It should also be appreciated that various modifications, adaptations, and alternative embodiments thereof may be made within the scope and spirit of the present invention. The invention is further defined by the following claims.

Claims

What is claimed is :

1. A power conversion circuit, including: a power module for providing a constant current as source current ; a plurality of branch circuits, each of which being coupled to the power module, and each branch circuit at least including: a switch component; and a capacitor, coupled to the switch component in series; and a control module, connected to each of the branch circuits via being coupled to the switch component of each of the branch circuits to control the switch component to switch on by monitoring change of the voltage of each of the branch circuits.

2. The power conversion circuit of claim 1, wherein the power ' module is an isolated constant current source.

3. The power conversion circuit of claim 1 or 2, wherein the switch component is an active switch component.

4. The power conversion circuit of claim 3, wherein the switch component is a Metallic Oxide Semiconductor Field Effect

I Transistor (MOSFET) , the MOSFET being coupled to the control module via its gate.

5. The power conversion circuit of claim 1 or 2 or 4, wherein the capacitor is a super capacitor.

6. The power conversion circuit of claim 1, wherein the control module switches on the switch component when monitoring that the voltage of the branch circuit which includes the switch component is less than a pre-set voltage and control time is distributed to the branch circuit according to a control scheme.

7. The power conversion circuit of claim 6, wherein the control scheme is produced via a programmable control mechanism and the control mechanism can be programmed through the control module .

8. A power conversion device with the power conversion circuit as claimed in one of the preceding claims.

9. A method of power conversion, the method including: providing a constant current as source current by a power module; monitoring change of the voltage of each of branch circuits by a control module; delivering the source current to any of the branch circuits by means of the control module switching on a switch component of the branch circuit according to the monitored change; and converting the voltage of the branch circuit by charging a capacitor based on the delivered current, wherein the capacitor is set in the branch circuit and coupled to the switch component.

10. The method of claim 9, wherein the power module is an isolated constant current source.

11. The method of claim 9 or 10, wherein the switch component is an active switch component.

12. The method of claim 11, wherein the switch component is a Metallic Oxide Semiconductor Field Effect Transistor (MOSFET) , the MOSFET being coupled to the control module via its gate.

13. The method of claim 9 or 12, wherein the capacitor is a super capacity .

14. The method of claim 9, wherein delivering the source current to the branch circuits when the control module monitors that the voltage of the branch circuit is less than a pre-set voltage for the branch circuit, during control time being distributed to the branch circuit according to a control scheme.

15. The method of claim 14, wherein the control scheme is produced via a programmable control mechanism by the control module.