Multi-port buck-boost converter and control method

Abstract

An illustrative example embodiment of a buck-boost converter includes at least three input / output ports, at least three switch sets, and at least two ripple current limiters. One switch set is associated with each input / output port. Each ripple current limiter is associated with a corresponding switch set within the switch sets, and each ripple current limiter is located between the associated switch set and the other switch set.

Description

Background Technology

[0001] Buck-boost converters are useful for controlling the amount of power delivered to a load. For example, a buck-boost DC-DC converter is useful for raising or lowering the input voltage. When the voltage supplied to the load is too high, the converter lowers the voltage to the load. Alternatively, when the power supply cannot provide the required voltage, the converter can raise the output voltage to the load. These two regulation types can be used at different times to meet the needs of different situations.

[0002] Buck-boost converters have proven useful as interfaces in hybrid energy storage systems for adjustable control of battery charge distribution and in power supply arrangements involving wide ranges of input and output voltages. Despite their proven usefulness, buck-boost converters are not without limitations. Traditional buck-boost converters have only one input port and one input / output port, with a switch located between them. This necessitates multiple converters, for example, in cases with multiple loads, increasing system cost. Another drawback is that the switching control in many buck-boost converters tends to introduce additional ripple current, requiring more robust and expensive components. Summary of the Invention

[0003] An illustrative example embodiment of a buck-boost converter includes at least three input / output ports, at least three switch sets, and at least two ripple current limiters. One switch set is associated with each input / output port. Each ripple current limiter is associated with a corresponding switch set within the switch sets, and each ripple current limiter is located between the associated switch set and the other switch set.

[0004] In addition to one or more of the features described above, or as an alternative, the first ripple current limiter in the ripple current limiter is associated with one of the input / output ports, the second ripple current limiter in the ripple current limiter is associated with another input / output port, and the first ripple current limiter in the ripple current limiter and the second ripple current limiter in the ripple current limiter are connected in series.

[0005] In addition to one or more of the features described above, or as an alternative, the first ripple current limiter in the ripple current limiter includes a sensor, and the second ripple current limiter in the ripple current limiter includes a sensor.

[0006] In addition to one or more of the features described above, or as an alternative, the first ripple current limiter in the ripple current limiter is associated with one of the input / output ports, the second ripple current limiter in the ripple current limiter is associated with another input / output port, and the first ripple current limiter in the ripple current limiter and the second ripple current limiter in the ripple current limiter are connected in parallel.

[0007] In addition to one or more of the features described above, or as an alternative, the first ripple current limiter in the ripple current limiter includes a sensor, and the second ripple current limiter in the ripple current limiter includes a sensor.

[0008] In addition to one or more of the features described above, or as an alternative, each ripple current limiter in the ripple current limiter includes a sensor.

[0009] In addition to one or more of the features described above, or as an alternative, the set of switches associated with the first input / output port includes a first switch and a second switch, wherein a first switch connector couples one side of the first switch to one side of the second switch; the set of switches associated with the second input / output port includes a third switch and a fourth switch, wherein a second switch connector couples one side of the third switch to one side of the fourth switch; the set of switches associated with the third input / output port includes a fifth switch and a sixth switch, wherein a third switch connector couples one side of the fifth switch to one side of the sixth switch; a first ripple current limiter in the ripple current limiter is connected between the first switch connector and the second switch connector; and a second ripple current limiter in the ripple current limiter is connected between the first switch connector and the third switch connector.

[0010] In addition to one or more of the features described above, or as an alternative, the first ripple current limiter in the ripple current limiter is connected in series with the second ripple current limiter in the ripple current limiter.

[0011] In addition to one or more of the features described above, or as an alternative, the first ripple current limiter in the ripple current limiter runs in parallel with the second ripple current limiter in the ripple current limiter.

[0012] In addition to one or more of the features described above, or as an alternative, the buck-boost converter includes a controller for controlling the operation of switches, a first switch having a side connected to the positive terminal of a first input / output port, a second switch having a side connected to the negative terminal of the first input / output port, a third switch having a side connected to the positive terminal of a second input / output port, and a fourth switch having a side connected to the negative terminal of the second input / output port. The controller can selectively provide switch activation signals to the switches, the switch activation signals provided to the first switch being synchronized with the switch activation signals provided to the third switch, and the phase of the switch activation signals provided to the first switch being the same as the phase of the switch activation signals provided to the third switch for at least a majority of the period.

[0013] In addition to one or more of the features described above, or as an alternative, the phase of the switch activation signal provided to the second switch is the same as the phase of the switch activation signal provided to the fourth switch for at least most of the period.

[0014] A method for controlling a buck-boost converter having at least three input / output ports and at least two associated ripple current limiters, wherein each of the input / output ports has a plurality of associated switches, the method comprising: providing a synchronized switch activation signal to a switch having a side connected to a positive terminal of an associated input / output port, the synchronized switch activation signals having the same phase for at least a majority of a period; and providing another synchronized switch activation signal to a switch having a side connected to a negative terminal of an associated input / output port, the other synchronized switch activation signal having the same phase for at least a majority of a period.

[0015] In addition to one or more of the features described above, or as an alternative, the synchronous switch activation signal has a first phase during a portion of the cycle, and other synchronous switch activation signals have a second opposite phase during that portion of the cycle.

[0016] In addition to one or more of the features described above, or as an alternative, each ripple current limiter includes a sensor.

[0017] In addition to one or more of the features described above, or as an alternative, the method includes selectively controlling the switch to transfer power from a first input / output port to a second input / output port during at least one time period, and to transfer power from the second input / output port to the first input / output port during at least one other time period.

[0018] From the following detailed description, various features and advantages of at least one of the disclosed exemplary embodiments will become apparent to those skilled in the art. The accompanying drawings, accompanying the detailed description, can be briefly described below. Attached Figure Description

[0019] Figure 1 A buck-boost converter configuration including at least three input / output ports and a ripple current limiter associated with each input / output port is schematically illustrated.

[0020] Figure 2 Another buck-boost converter configuration is illustrated schematically.

[0021] Figure 3 The diagram schematically illustrates the activation process. Figure 1 or Figure 2 The switching control technology of the buck-boost converter in the process.

[0022] Figure 4 The illustration schematically depicts, including, as Figure 1 or Figure 2 The buck-boost converter shown is a selected feature of the elevator car. Detailed Implementation

[0023] Figure 1 An example embodiment of a buck-boost converter 20 including at least three input / output ports is schematically illustrated. A first input / output port 22 is configured to be connected to a power source when used as an input port, or to a load when used as an output port. A first set of switches (including a first switch 24 and a second switch 26) is associated with the first input / output port 22. In this embodiment, a first capacitor 28 is parallel to switches 24 and 26.

[0024] The second input / output port 32 is configured to connect to a load when used as an output port, or to connect to a power source when used as an input port. The second set of switches includes a third switch 34 and a fourth switch 36, which are associated with the input / output port 32. A capacitor 28, operating in a known manner, is associated with the input / output port 32.

[0025] The first ripple current limiter 40 is associated with the second set of switches 34, 36. In this embodiment, the ripple current limiter 40 includes a sensor. The ripple current limiter 40 decouples the input / output port 32 from the input / output port 22 and components associated with the input / output port 22 (e.g., switches 24, 26 and capacitor 28). The sensor of the ripple current limiter 40 also provides other known functions, such as storing electrical energy when capacitor 38 discharges to transfer power at the input / output port 32, or releasing stored electrical energy to charge capacitor 38.

[0026] The third input / output port 42 is configured to connect to another load when used as an output port, or to connect to a power source when used as an input port. A third set of switches (including the fifth switch 44 and the sixth switch 46) is associated with the third input / output port 42. When needed, a capacitor 48 supplies power to the third input / output port 42.

[0027] The second ripple current limiter 50 is associated with the third switch sets 44, 46 to decouple at least input / output port 42 from input / output port 22 and the components associated with input / output port 22. The second ripple current limiter 50 includes at least a sensor.

[0028] The first switch connector 52 connects one side of the first switch 24 to one side of the second switch 26. The second switch connector 54 connects one side of the third switch 34 to one side of the fourth switch 36. The third switch connector 56 connects one side of the fifth switch 44 to one side of the sixth switch 46.

[0029] exist Figure 1 In this embodiment, ripple current limiters 40 and 50 are connected in series. The first ripple current limiter 40 is connected to a first switch connector 52 between switches 24 and 26, and to a second switch connector 54 between switches 34 and 36. The second ripple current limiter 50 is connected to a third switch connector 56 between switches 44 and 46, and to the first switch connector 54 connected in series with the first ripple current limiter 40.

[0030] Each ripple current limiter 40, 50 operates to decouple the associated input / output ports 32, 42 and their corresponding components from the rest of the buck-boost converter 20. The inclusion of independent or dedicated ripple current limiters 40, 50 for each input / output port 32, 42 allows for the inclusion of multiple input / output ports within a single buck-boost converter 20. Although Figure 1 Three input / output ports 22, 32, and 42 are shown, but additional input / output ports and associated ripple current limiters may also be included.

[0031] Controller 60 controls the operation of switches 24, 26, 34, 36, 44, and 46 to achieve a desired conversion of power or voltage from an input power source coupled to at least one of the input / output ports 22, 32, and 42, so as to transfer the converted power or voltage to at least one other port. Controller 60 is configured to independently control the switches such that a different output can be provided at each of the input / output ports used as output ports. This allows for the supply of power to different loads with different power requirements via a single buck-boost converter 20.

[0032] The input / output ports are each configured to function as either input or output ports to meet the needs of a specific implementation or installation, and the controller 60 is configured to control the switch in a manner that allows bidirectional power transfer via the buck-boost converter 20.

[0033] For example, when a power source is coupled to the first input / output port 22 and a load is coupled to input / output ports 32 and 42, the assembly includes one input port and two output ports. Switches 24 and 26 can be considered input switches, and switches 34, 36, 44, and 46 can be considered output switches. Ripple current limiters 40 and 50 are each associated with a corresponding set of output switches in the output switch set, located between the associated output switch set and the input switch. Figure 1 Power transfer occurs from left to right. Alternatively, input / output port 22 can be connected to a load, and at least one of input / output ports 32 or 42 can be connected to a power source. In that case, power transfer occurs... Figure 1 The lieutenant general was at least partially from right to left.

[0034] Alternatively, the same buck-boost converter 20 can be used to transfer power from one port to another during one time period and transfer power between the two ports in the opposite direction during another time period. This can be useful, for example, when the load includes a motor that draws current when operating as a motor and generates current when operating as a generator or in regenerative mode. The controller 60 controls the switches associated with the corresponding input / output ports to use that interface as an output port and an input port respectively during those different conditions.

[0035] The controller 60 includes a computing device (e.g., a microprocessor) and a memory containing instructions that are executed by the controller 60 to achieve the desired converter operation. This manner (in which the switching of the buck-boost converter causes the transmission of the desired output (which can be boosted or deboosted)) is known to those skilled in the art and will not be described further herein.

[0036] Figure 2 Another configuration of the buck-boost converter 20 is shown. In this example embodiment, the figure shows a fourth input / output port 62. The fourth input / output port 62 has an associated set of switches, including a seventh switch 64 and an eighth switch 66. Another capacitor 68 provides electrical power at the fourth input / output port 62 under appropriate conditions.

[0037] A ripple current limiter 70 (e.g., an inductor) decouples the fourth input / output port 62 and its associated components from the rest of the buck-boost converter 20. The ripple current limiter 70 is connected between the first switch connector 52 and the fourth switch connector 74. In this example, the controller 60 is configured to control or operate the switches to achieve desired power transfer between selected ports 22, 32, 42, and 62.

[0038] In this example, ripple current limiters 40, 50, and 70 are arranged in parallel. Compared to a serial configuration, a parallel circuit configuration facilitates easier accommodation of additional ports. Additional ports with associated ripple current limiters can be placed in parallel with the ports shown in the diagram. Figure 1 Compared to the serial configuration in the middle, Figure 2 Another difference in the parallel configuration of the ripple current limiter is that the parallel configuration reduces the loss for different interfaces because the current does not need to pass through any intermediate ripple current limiter between the selected set of input / output ports 22, 32, 42, 62.

[0039] As in the example above, it is possible to use any port in the port as an input or output by using appropriate control switches.

[0040] Example controller 60 is configured to use a unique control strategy to control switch operation. Figure 3 The diagram schematically illustrates the control or activation signals provided by the controller to the switches, including control signal 80 for the first switch 24, control signal 82 for the third switch 34, control signal 84 for the fifth switch 44, and control signal 86 for the seventh switch 64. A characteristic of control signals 80, 82, 84, and 86 is that they have the same phase for most of their cycle. Figure 3 The diagram illustrates a cycle. For example, the periods during which control signals 82, 84, and 86 are low overlap with the periods during which control signal 80 is low. During those periods, the signals all have the same phase.

[0041] The controller also provides control signal 90 to the second switch 26, control signal 92 to the fourth switch 36, control signal 94 to the sixth switch 46, and control signal 96 to the eighth switch 66. These control signals have the same phase for most of the cycle.

[0042] Switches 24, 34, 44, and 64, located between the respective ripple current limiters and the positive terminals of their associated ports, each have a control or activation signal synchronized to have the same phase for most of the cycle. Similarly, switches 26, 36, 46, and 66, located between the respective ripple current limiters and the negative terminals of their associated ports, each have a control signal synchronized to have the same phase for most of the cycle. By maintaining the same phase of the control signals in this way, the controller 60 reduces or minimizes the ripple current in the buck-boost converter 20. Reducing or minimizing the ripple current reduces the need for sensors in the ripple current limiters, allowing the use of less expensive components. Therefore, Figure 3 The control technology shown in the diagram provides cost savings.

[0043] As shown in the accompanying drawings and described above, the buck-boost converter 20 is useful in a variety of situations. Figure 4 An example implementation from elevator system 100 is shown. In this example, elevator car 102 has on-board power sources 104 and 105, which eliminates the need for a traveling cable to be connected to elevator car 102. In this example, a buck-boost converter 20 serves as an interface between power sources 104 and 105 and multiple loads, each of which is coupled to a corresponding input / output port in the buck-boost converter 20. For example, the car operation panel (COP) 106, elevator car lighting 108, and door mover 110 all have different power requirements. A single buck-boost converter 20, including multiple input / output ports, is controlled to supply those different power levels to loads 106-110.

[0044] By utilizing embodiments of buck-boost converters consistent with this description, it is possible to reduce the number of converters required to supply power to multiple different loads or receive power from multiple different power sources. Reducing the number of converters required lowers costs. Embodiments of switching control strategies, including those described above, can offer additional cost savings because ripple current limiter components (e.g., inductors) can be made less robust and less expensive.

[0045] The foregoing description is exemplary in nature and not limiting. Variations and modifications to the disclosed examples that do not necessarily depart from the spirit of the invention will become apparent to those skilled in the art. The scope of legal protection afforded to this invention can only be determined by studying the following claims.

Claims

1. A buck-boost converter, comprising: At least three input / output ports; At least three sets of switches, each associated with one of the at least three input / output ports; At least two ripple current limiters, each ripple current limiter being associated with two corresponding switch sets from the at least three switch sets; as well as A controller that controls the operation of switches in the at least three switch sets by providing switch activation signals. Specifically, the first switch activation signal provided to the first switch in the first switch set connected to the positive terminal of the first input / output port is synchronized with the third switch activation signal provided to the third switch in the second switch set connected to the positive terminal of the second input / output port. During at least most of the period, the phase of the first switch activation signal is the same as the phase of the third switch activation signal, and The time during which the third switch activation signal is low overlaps with the time during which the first switch activation signal is low, but is less than the time during which the first switch activation signal is low.

2. The buck-boost converter as described in claim 1, wherein... The first ripple current limiter in the ripple current limiter is associated with one of the input / output ports; The second ripple current limiter in the ripple current limiter is associated with another input / output port in the input / output ports; and The first ripple current limiter in the ripple current limiter is connected in series with the second ripple current limiter in the ripple current limiter.

3. The buck-boost converter of claim 2, wherein, The first ripple current limiter in the ripple current limiter includes a sensor, and the second ripple current limiter in the ripple current limiter also includes a sensor.

4. The buck-boost converter as described in claim 1, wherein... The first ripple current limiter in the ripple current limiter is associated with one of the input / output ports; The second ripple current limiter in the ripple current limiter is associated with another input / output port in the input / output ports; and The first ripple current limiter in the ripple current limiter is connected in parallel with the second ripple current limiter in the ripple current limiter.

5. The buck-boost converter of claim 4, wherein, The first ripple current limiter in the ripple current limiter includes a sensor, and the second ripple current limiter in the ripple current limiter also includes a sensor.

6. The buck-boost converter of claim 4, wherein, Each of the ripple current limiters includes a sensor.

7. The buck-boost converter as claimed in claim 1, wherein... The first set of switches associated with the first input / output port includes the first switch and the second switch, wherein the first switch connector couples one side of the first switch to one side of the second switch. The second set of switches associated with the second input / output port includes the third switch and the fourth switch, wherein the second switch connector couples one side of the third switch to one side of the fourth switch. The third set of switches associated with the third input / output port includes a fifth switch and a sixth switch, wherein the third switch connector couples one side of the fifth switch to one side of the sixth switch.

8. The buck-boost converter of claim 7, wherein, The first ripple current limiter in the ripple current limiter is connected between the first switch connector and the second switch connector, and the second ripple current limiter in the ripple current limiter is connected between the second switch connector and the third switch connector, such that the first ripple current limiter in the ripple current limiter and the second ripple current limiter in the ripple current limiter are connected in series.

9. The buck-boost converter of claim 7, wherein, The first ripple current limiter in the ripple current limiter is connected between the first switch connector and the second switch connector, and the second ripple current limiter in the ripple current limiter is connected between the first switch connector and the third switch connector, such that the first ripple current limiter in the ripple current limiter and the second ripple current limiter in the ripple current limiter run in parallel.

10. The buck-boost converter as claimed in claim 8 or 9, wherein The first switch has one side that is connected to the positive terminal of the first input / output port. The second switch has one side that is connected to the negative terminal of the first input / output port. The third switch has one side that is connected to the positive terminal of the second input / output port. The fourth switch has one side connected to the negative terminal of the second input / output port.

11. The buck-boost converter of claim 10, wherein, For at least most of the period, the phase of the second switch activation signal provided to the second switch is the same as the phase of the fourth switch activation signal provided to the fourth switch.

12. A method of controlling a buck-boost converter, wherein the buck-boost converter comprises: At least three input / output ports; at least three sets of switches associated with each of the at least three input / output ports; At least two ripple current limiters, each ripple current limiter being associated with two corresponding switch sets from the at least three switch sets; and a controller, which controls the operation of switches in the at least three switch sets by providing switch activation signals. The method includes: A synchronized switch activation signal is provided to a switch having a positive terminal connected to an associated input / output port on one side. The synchronized switch activation signals have the same phase for at least a majority of the period, wherein a first switch activation signal is provided to a first switch connected to the positive terminal of a first input / output port, a third switch activation signal is provided to a third switch connected to the positive terminal of a second input / output port, and the period during which the third switch activation signal is low overlaps with, but is less than, the period during which the first switch activation signal is low. Additional synchronous switch activation signals are provided to the switch on the side having a negative terminal connected to the associated input / output port, the additional synchronous switch activation signals having the same phase for at least a majority of the cycle.

13. The method of claim 12, wherein, The synchronized switch activation signal has a first phase during a portion of the cycle, and the other synchronized switch activation signal has a second opposite phase during the same portion of the cycle.

14. The method of claim 12, wherein, Each of the at least two ripple current limiters includes a sensor.

15. The method of claim 12, comprising controlling respective switches in the at least three switch sets to transmit power from a first input / output port of the at least three input / output ports to a second input / output port of the at least three input / output ports during at least one time period, and to transmit power from the second input / output port of the at least three input / output ports to the first input / output port of the at least three input / output ports during at least one other time period.

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