Multiphase power converter

Abstract

A method of controlling a multiphase power converter (2) including a plurality of phases (4a, 4b). Each of the plurality of phases (4a, 4b) includes a bidirectional power converter (6a, 6b), a first side (8a, 8b) and a second side (10a, 10b). The first sides (8a, 8b) are connected together at a first node (12) and the second sides (10a, 10b) are connected together at a second node (14). The method includes a simultaneous control step of simultaneously controlling a first phase (4a) such that power flows from the first side (8a) of the first phase (4a) to the second side (10a) of the first phase (4a) and a second phase (4b) such that power flows from the second side (10b) of the second phase (4b) to the first side (8b) of the second phase (4b).

Description

[0001] Multiphase power converter

[0002] Technical Field

[0003] This disclosure relates to a method and system for controlling a multiphase power converter. In particular, the disclosure relates to controlling a multiphase power converter to facilitate testing of the multiphase power converter.

[0004] Background Art

[0005] Multiphase power converters are commonly used in power electronics for a variety of reasons, such as to increase efficiency, spread power dissipation, reduce cooling requirements, increase redundancy and / or decrease ripple in the power output.

[0006] Testing the performance of a multiphase power converter has typically been done by connecting a second multiphase power converter to the output of the first multiphase power converter and the output of the second multiphase power converter back to the input of the first multiphase power converter such that power flows through the two multiphase power converters in a closed loop. However, this method involves disconnecting the multiphase power converter from other components, such as a power source and / or a power sink (or load). This can be time consuming and inconvenient, especially when the multiphase power converter forms part of a larger system or a consumer product. Furthermore, a second multiphase power converter is required for the testing.

[0007] Summary of the Disclosure

[0008] According to a first aspect of the present disclosure, there is provided a method of controlling a multiphase power converter, wherein the multiphase power converter comprises a plurality of phases; wherein each of the plurality of phases comprises a bidirectional power converter; wherein each of the plurality of phases comprises a first side and a second side; wherein the first sides of the plurality of phases are connected together at a first node; wherein the second sides of the plurality of phases are connected together at a second node; and wherein the method comprises a simultaneous control step of simultaneously controlling: a first phase of the multiphase power converter such that power flows from the first side of the first phase to the second side of the first phase; and a second phase of the multiphase power converter such that power flows from the second side of the second phase to the first side of the second phase.

[0009] According to this arrangement, power through the first phase of the converter can be recirculated back through the second phase of the converter, thereby allowing both phases to be operated simultaneously (potentially at high power throughput) without significant overall power consumption. The only power input that is required during such operation is to make up for any losses in the bidirectional power converters of the first phase and the second phase (although, as discussed below, in some examples not all power needs to be recirculated). Additionally, as power can be recirculated within the multiphase power converter, there is no need for a second multiphase power converter to be provided in order to perform testing or analysis. Nor is there any need for the multiphase power converter to be disconnected from other circuits for such testing or analysis.

[0010] The multiphase power converter may be any type. The multiphase power converter may be configured to receive power (e.g. at the first node) and provide a different power output (e.g. at the second node). The multiphase power converter may be connectable to a power source (e.g. at the first node), wherein the power source may be configured to provide power to the multiphase power converter. The multiphase power converter may be connectable to a power sink (e.g. at the second node), wherein optionally the power sink may be configured to receive power from the multiphase power converter.

[0011] The multiphase power converter may be configured as a buck converter, a boost converter or a buck-boost converter. The multiphase power converter may be configured as an AC-AC converter, an AC-DC converter, a DC-AC converter or a DC-DC converter.

[0012] The multiphase power converter may include any number of phases (e.g. two, three, four, eight, ten or more phases). Each phase of the plurality of phases comprises a bidirectional power converter, which may each be any type. However, in some examples, the bidirectional power converters are each the same, i.e. each phase comprises the same type of bidirectional power converter. Having converters of the same type may allow for easier comparison between two phases. For example, if the first phase and the second phase are each of the same type then certain characteristics can be expected to be the same (or at least similar), allowing for easier analysis. The bidirectional power converters may each be configured as a buck converter, each as a boost converter or each as a buck-boost converter. The bidirectional power converters may each be configured as an AC-AC converter, an AC-DC converter, a DC-AC converter or a DC-DC converter.

[0013] In some examples, one or more of the plurality of phases comprises additional components such as a local controller and / or one or more monitoring devices (e.g. a voltage sensor, a current sensor, a temperature sensor).

[0014] In some examples, the first side of the first phase may be understood as the path between the first node and the input of the bidirectional power converter of the first phase. The second side of the first phase may be understood as the path between the output of the bidirectional power converter of the first phase and the second node. The second side of the second phase may be understood as the path between the second node and the input of the bidirectional power converter of the second phase. The first side of the second phase may be understood as the path between the output of the bidirectional power converter of the second phase and the first node.

[0015] The method of the present disclosure includes a simultaneous control step for controlling the multiphase power converter. This step includes controlling the first phase of the multiphase power converter such that power flows from the first side of the first phase to the second side of the first phase. At the same time (i.e. simultaneously), the second phase of the multiphase power converter is controlled such that power flows from the second side of the second phase to the first side of the second phase.

[0016] Therefore, at least a portion of the power flowing from the second side of the first phase flows into the second side of the second phase, and at least a portion of the power flowing from the first side of the second phase flows into the first side of the first phase. Accordingly, at least a portion of the power can circulate within the multiphase power converter. This may help to reduce the power required to perform certain operations on the multiphase power converter. This will be discussed in more detail below.

[0017] In some examples, controlling the first phase of the multiphase power converter comprises controlling the first phase to provide a particular voltage. The particular voltage may comprise a particular magnitude and / or a particular polarity.

[0018] In some examples, controlling the second phase of the multiphase power converter comprises controlling the second phase to provide a particular current. The particular current may comprise a particular magnitude and / or a particular polarity.

[0019] In some examples, controlling the first phase of the multiphase power converter comprises controlling the first phase to provide a particular voltage and controlling the second phase of the multiphase power converter comprises controlling the second phase to provide a particular current. This may help to ensure that the two phases are able to self-regulate with respect to one another. As each phase is only limited by the control step to provide a particular voltage or a particular current, the respective current or voltage of each phase may be regulated (e.g. by the phase itself) such that the power flowing through each phase is consistent with the power required by other limitations of the circuit.

[0020] This may be particularly advantageous if there is a requirement that the power flowing on the second side of the first phase should be substantially equal to the power flowing on the second side of the second phase (e.g. when no power is being provided to a sink). For example, the control step may comprise controlling the first phase to provide a particular voltage on its second side and controlling the second phase to provide a particular current throughput. The first phase can then regulate its current (in order to provide the particular voltage according to the control step) and the second phase can regulate the voltage on its second side (in order to provide the particular current according to the control step), such that the power flowing on the second side of the first phase is substantially equal to the power flowing on the second side of the second phase.

[0021] In some examples, the method further comprises, for at least one phase, the steps of: measuring at least one characteristic of the phase; and determining a performance indicator of the phase from the measurement.

[0022] The at least one characteristic may be measured in any way. In some examples, the at least one phase may comprise one or more monitoring devices (e.g. a voltage sensor, a current sensor, a temperature sensor, etc.). In some examples, the one or more monitoring devices may be located in or placed proximal to the phase. The one or more monitoring devices may be configured to provide an output corresponding to the at least one characteristic of the phase (e.g. a signal indicative of voltage, current or temperature). The output may be used to determine a performance indicator of the phase.

[0023] In some examples, the characteristic comprises one or more of: a voltage across the phase; a current through the phase; a temperature associated with the phase; and a duty cycle associated with the phase.

[0024] The performance indicator of the phase may be determined in any way. In some examples, the measurement(s) from the monitoring device(s) may be communicated to a processor configured to determine a performance indicator of the phase from the measurement(s).

[0025] The performance indicator may take many forms. For example, the performance indicator may be indicative of one or more of: a rate of change of the characteristic; the difference between the measured value(s) of the characteristic and a target value of the characteristic; the response time to a control signal based on one or more values of the characteristic; the efficiency of the phase and / or one or more predicted values of the characteristic.

[0026] The determined value of the performance indicator may be used to identify potential operational problems in one or more phases of the multiphase power converter. An indication that there may be an operational problem may be provided as an output (e.g. to a user) and / or stored (e.g. in a log file) to form a record of the performance of the multiphase power converter. The performance indicator may be used to help determine what action should be taken to address potential operational problems and when such action should be taken. This may help to ensure that potential operational problems are addressed, thereby helping to maintain and / or improve the performance of the multiphase power converter.

[0027] In some examples, the power flowing on the second side of the first phase is substantially equal in magnitude to the power flowing on the second side of the second phase. The power flowing on the second side of the first phase may flow directly into the second side of the second phase via the second node. The multiphase power converter may be operated in this manner in order to test both the first and second phases at substantially the same power (e.g. at a desired operating power). Operating the multiphase power converter in this manner may help to reduce the power required to test the multiphase power converter because the power used to test the first phase is also used to test the second phase.

[0028] In some examples, a power source is connected to the multiphase power converter at the first node; and wherein the method comprises the step of: controlling the power source to supply power to the multiphase power converter.

[0029] The power source may be any type, for example a cell, a battery or a mains power source. The power source may be configured to provide AC or DC power as appropriate. The power source may be configured to provide power to the multiphase power converter in order to facilitate power flow through the multiphase power converter as described above, thereby facilitating testing of the multiphase power converter if desired. The power source may be configured to provide power to the power sink via the multiphase power converter.

[0030] In some examples, the power supplied by the power source is equal to the difference between the power flowing on the first side of the first phase and the power flowing on the first side of the second phase.

[0031] The power flowing on the first side of the first phase and the power flowing on the first side of the second phase may be different owing to power losses in the multiphase power converter (e.g. loss of power across the bidirectional power converters) and / or owing to power being supplied from the multiphase power converter to another component (e.g. a power sink). The power source may be configured to supply the power that has been lost and / or supplied to another component. This may help to ensure that there is sufficient power flowing in the multiphase power converter, for example to perform tests on one or more of the phases at the desired power and / or to supply power to another component.

[0032] In some examples, the multiphase power converter does not supply power to a power sink. Thus, the only substantial power loss in the multiphase power converter may be the loss of power across the bidirectional power converters. Bidirectional power converters generally have high efficiency (e.g. in excess of 90%). Hence, the power required from the power source may be an order of magnitude smaller than the power flowing through the first phase and the second phase. As the power source only needs to supply energy to cover the power loss, the phases can be tested at high power with low power consumption.

[0033] Hence, the method and system according to the present disclosure may help to ensure that testing of the multiphase power converter can be carried out using a relatively small amount of power. This may be particularly advantageous for multiphase power converters, especially where they are used in systems with high current and / or high power requirements, e.g. in electric vehicles. This may help to ensure that the multiphase power converter may be tested more easily, more frequently and / or more conveniently. By testing the multiphase power converter more frequently, issues with the performance may be identified and addressed more quickly, thereby helping to facilitate performance improvements compared to a system that is tested less frequently.

[0034] Even when power is being supplied to a power sink, the excess power required for testing one or more phases of the multiphase power converter is still only determined by the power loss across the phases. Hence, the excess power required for testing may still be an order of magnitude smaller than the power flowing through the phases, as set out above.

[0035] In some examples, a power sink is connected to the multiphase power converter at the second node; and wherein the method comprises the step of: controlling the multiphase power converter to supply power to the power sink.

[0036] The power sink is configured to receive power from the multiphase power converter. The power sink may be configured to receive AC or DC power. The power sink may be any type, e.g. any electrical load. For example, the power sink may be a device that consumes power such as an electric vehicle. The power sink may be an energy storage device such as a cell or a battery.

[0037] The step of controlling the multiphase power converter to supply power to the power sink may take place at the same time as (i.e. simultaneously with) the simultaneous control step of the method. In some examples, power may be supplied to the power sink while one or more phases of the multiphase power converter are undergoing testing (e.g. measuring at least one characteristic of the phase and determining a performance indicator of the phase from the measurement). Being able to test the multiphase power converter while the multiphase power converter is operational (e.g. supplying power to a power sink) may allow the multiphase power converter to be tested more easily, more frequently and / or more conveniently. By testing the multiphase power converter more frequently, issues with the performance may be identified and addressed more quickly, thereby facilitating performance improvements compared to a system that is tested less frequently. The method and system of the present disclosure may facilitate this mode of operation because only a small amount of power may be required for testing the phases of the multiphase power converter.

[0038] In some examples, the first and second phases (and any further phases being controlled in the simultaneous control step and / or undergoing testing) may not contribute to the multiphase power converter supplying power to the sink. Instead, the power flowing through these phases may flow through another phase of the multiphase power converter. This may help to ensure that there is sufficient power to perform test operations on these phases. Therefore, the first and second phases (and any further phases being controlled in the simultaneous control step and / or undergoing testing) may be different phases from those supplying power to the power sink. Such test operations may be performed when the multiphase power converter has a low power demand that does not require all phases to supply power to the load. For example, when at least two phases are not required for supplying the load, those phases may be tested as discussed above, without impacting any simultaneous power supply to the load.

[0039] The method and system according to the present disclosure may allow the multiphase power converter to be tested without being disconnected from the power source and power sink and without any further equipment being required for testing. The (typically small) amount of power required for testing may be provided by the power source. This power circulates internally from one phase to another in order to perform tests. This may be particularly advantageous when the multiphase power converter is part of a larger system and / or a product, whereby removing the multiphase power converter for testing is time consuming and inconvenient. Being able to test the multiphase power converter without disconnecting it from the power source and power sink may allow the multiphase power converter to be tested more easily, more frequently and / or more conveniently. By testing the multiphase power converter more frequently, issues with the performance may be identified and addressed more quickly, thereby helping to facilitate performance improvements compared to a system that is tested less frequently.

[0040] In some examples, the method further comprises the step of simultaneously controlling: the first phase of the multiphase power converter such that power flows from the second side of the first phase to the first side of the first phase; and the second phase of the multiphase power converter such that power flows from the first side of the second phase to the second side of the second phase.

[0041] That is, the direction of power flow may be reversed compared to the first simultaneous control step of the method. This is possible owing to the bidirectional power converters being configured to accept power flow in both directions.

[0042] In some examples, one or more steps of the method may be repeated after the direction of the power flow has been reversed. In particular, the steps of (for at least one phase): measuring at least one characteristic of the phase; and determining a performance indicator of the phase from the measurement may be repeated after the direction of the power flow has been reversed. This step may be used to determine whether the performance of the phase is substantially the same when power flows in each direction through the phase. In addition, two similar phases can be compared under similar operating conditions. That is, by carrying out one operation with current circulation in one direction followed by a second operation with current circulation in the opposite direction, both bidirectional converters can be tested with the same power flow in the same direction, which may allow better comparison of the two phases and better identification of any problems or discrepancies.

[0043] In some examples, the steps of the method are carried out during a power-up stage of the multiphase power converter. The power-up stage may be a period of time shortly after (e.g. immediately after) the multiphase power converter is switched on. The power-up stage may end when the multiphase power converter begins to perform operations such as providing power to a power sink. Carrying out the steps of the method during a power-up stage may allow tests to be performed on one or more phases of the multiphase power converter before the multiphase power converter becomes (e.g. fully) operational. This may help to ensure that problems are identified and / or addressed before the multiphase power converter is required to perform other operations. The steps of the method may be particularly well suited to being performed during a power-up stage because only a relatively small amount of power is required from an external power source to perform the tests, compared to the power circulating within the multiphase power converter.

[0044] In some examples, the steps of the method are repeated after a predetermined interval of time has elapsed. For example, the predetermined interval of time may be approximately a day, approximately a week, approximately a month, approximately a year. The predetermined interval of time may be determined and measured in any suitable way. Repeating the steps of the method after a predetermined interval of time has elapsed may facilitate more frequent and / or more regular testing of the multiphase power converter. This may help to ensure that problems are identified and / or addressed more quickly, compared to a system that is not tested as frequently and / or regularly.

[0045] In some examples, the multiphase power converter comprises a third phase and the third phase of the multiphase power converter is controlled simultaneously with the first phase such that power flows from the first side of the third phase to the second side of the third phase. Thus the third phase may be operated in parallel with the first phase, providing power flow in the same direction as the first phase.

[0046] In some examples, the multiphase power converter comprises a fourth phase and the fourth phase of the multiphase power converter is controlled simultaneously with the second phase such that power flows from the second side of the fourth phase to the first side of the fourth phase. Thus the fourth phase may be operated in parallel with the second phase, providing power flow in the same direction as the second phase.

[0047] Controlling the multiphase power converter such that power flows in the same direction through a plurality of phases may allow the power flow in one or more directions to be split between two phases (i.e. the first phase and the third phase and / or the second phase and the fourth phase). This may allow a greater number of phases to be tested at one time, which may help to decrease the time required to test the multiphase power converter.

[0048] Controlling the multiphase power converter such that power flows in the same direction through a plurality of phases may help to increase the flexibility and / or control to perform certain tests. For example, a particular phase may be tested at a different power without requiring that another phase is tested at substantially the same power. In some examples, the power flowing through a particular phase may be reduced (or prevented altogether) without preventing power from circulating through the multiphase power converter, as there are other phases available through which power may flow in the required direction.

[0049] In some examples, the multiphase power converter comprises at least three phases; and wherein the method comprises a plurality of test operations, each test operation comprising: selecting one of the at least three phases as the first phase; selecting another of the at least three phases as the second phase; and performing the simultaneous control step for the selected first phase and the selected second phase; wherein each test operation selects a different combination or permutation of the at least three phases for the first phase and the second phase.

[0050] Selecting a different combination or permutation of the at least three phases for the first phase and the second phase each time that the test operation is carried out may help to ensure that all three phases undergo testing as desired. For example, this may help to ensure that the phases are tested while power flows in each direction through each phase. A full set of permutations can provide a larger data set to compare the performances of the phases and thus provides more information from which to deduce any errors or performance issues.

[0051] According to a second aspect of the present disclosure, there is provided a system comprising: a multiphase power converter, wherein the multiphase power converter comprises a plurality of phases; wherein each of the plurality of phases comprises a bidirectional power converter; wherein each of the plurality of phases comprises a first side and a second side; wherein the first sides of the plurality of phases are connected together at a first node; wherein the second sides of the plurality of phases are connected together at a second node; and a controller configured to simultaneously control: a first phase of the multiphase power converter such that power flows from the first side of the first phase to the second side of the first phase; and a second phase of the multiphase power converter such that power flows from the second side of the second phase to the first side of the second phase.

[0052] It will be appreciated that the preferred and optional features that are described above in relation to the first aspect are equally applicable to the second aspect and will be understood to be preferred and optional features of that system.

[0053] The controller may be any type. The controller may be configured to send control signals to (e.g. each of) the phases of the multiphase power converter, the power source (where present) and the power sink (where present) via any means (e.g. wired or wireless and via any suitable transmission or control protocol).

[0054] In some examples, the controller is configured to receive feedback from the multiphase power converter. In some examples, the system comprises a monitoring means or monitoring device, which may be connected to the controller via the second node. The monitoring means or monitoring device may be configured to measure and / or determine a parameter representative of an output of the multiphase power converter. For example, the monitoring means or monitoring device may be configured to measure and / or determine the current, the voltage and / or the power at an output of the multiphase power converter.

[0055] The monitoring means or monitoring device may be configured to provide this information to the controller. The controller may adjust the control signals that it provides to the first and / or second phases according to the information it receives from the monitoring means or monitoring device. For example, if the monitoring means or monitoring device determines that the power is lower than intended, the controller may increase the particular current and / or voltage that it commands in its control signal. Hence, the monitoring means or monitoring device and the controller may be configured to operate as a feedback loop. This may help to ensure that the multiphase power converter is operating as intended.

[0056] In some examples, the controller is configured to receive feedback from one or more phases of the multiphase power converter. For example, each of the first and second phases may be configured to measure and / or determine a parameter representative of the performance of the first and second phases respectively. Each of the first and second phases may be configured to provide this information to the controller. The controller may adjust the control signals that it provides to the first and / or second phases according to this information. Hence, the first and second phases may provide a feedback loop to the controller. This may help to ensure that the multiphase power converter is operating as intended.

[0057] In some examples, the system further comprises a power source connected to the multiphase power converter at the first node; and wherein the controller is configured to control the power source to supply power to the multiphase power converter.

[0058] The controller may be configured to determine the power requirements of the system (in particular the multiphase power converter and / or the power sink or load where present), in order to control the power supply.

[0059] In some examples, the power supplied by the power source is equal to the difference between the power flowing on the first side of the first phase and the power flowing on the first side of the second phase. As discussed above, the power required from the power source may be an order of magnitude smaller than the power flowing through the first phase and the second phase.

[0060] In some examples, the system further comprises a power sink connected to the multiphase power converter at the second node; and wherein the controller is configured to control the multiphase power converter to supply power to the power sink. The controller may be configured to determine the power requirements of the power sink where present in order to control the multiphase power converter to supply power to the power sink. In some examples, the multiphase power converter does not supply power to the power sink.

[0061] In some example, the multiphase power converter comprises more than two phases; and the first and second phases do not contribute to the multiphase power converter supplying power to the sink.

[0062] In some examples, the first and second phases (and any further phases being controlled in the simultaneous control step and / or undergoing testing) do not contribute to the multiphase power converter supplying power to the sink. Instead, the power flowing through these phases may flow through another phase of the multiphase power converter. This may help to ensure that there is sufficient power to perform test operations on these phases. Therefore, the first and second phases (and any further phases being controlled in the simultaneous control step and / or undergoing testing) may be different phases from those supplying power to the power sink.

[0063] According to a third aspect of the present disclosure, there is provided a method of controlling a multiphase power converter, wherein the multiphase power converter comprises a plurality of phases; wherein each of the plurality of phases comprises a bidirectional power converter; wherein each of the plurality of phases comprises a first side and a second side; wherein the first sides of the plurality of phases are connected together at a first node; wherein the second sides of the plurality of phases are connected together at a second node; and wherein the method comprises the step of simultaneously: controlling a first set of phases of the multiphase power converter such that power flows from the first side to the second side of each phase in the first set of phases; controlling a second set of phases of the multiphase power converter such that power flows from the second side to the first side of each phase in the second set of phases.

[0064] According to a fourth aspect of the present disclosure, there is provided a system comprising: a multiphase power converter, wherein the multiphase power converter comprises a plurality of phases; wherein each of the plurality of phases comprises a bidirectional power converter; wherein each of the plurality of phases comprises a first side and a second side; wherein the first sides of the plurality of phases are connected together at a first node; wherein the second sides of the plurality of phases are connected together at a second node; and a controller configured to simultaneously control: a first set of phases of the multiphase power converter such that power flows from the first side to the second side of each phase in the first set of phases; and a second set of phases of the multiphase power converter such that power flows from the second side to the first side of each phase in the second set of phases.

[0065] It will be appreciated that the preferred and optional features that are described above in relation to the first and second aspects are equally applicable to the third and fourth aspects and will be understood to be preferred and optional features of that method and system.

[0066] In some examples, the method and / or system comprises controlling a third set of phases of the multiphase power converter to supply power to a power sink in accordance with a power demand from the power sink. In some examples, the first and second set of phases are different from the third set of phases. That is, in some examples the first and second set of phases do not supply power to the power sink. In some examples, the method and / or system comprises controlling a fourth set of phases of the multiphase power converter to block power flowing through each phase in the fourth set of phases. In some examples, the fourth set of phases are used neither for test operations nor for supplying power to the power sink. The fourth set of phases may not be required for operations such as testing or supplying power to the power sink. In some examples, blocking power from flowing through the fourth set of phases may be implemented in response to identifying an operational problem in the fourth set of phases. This may help to ensure that the phase(s) are not used if certain operational problems are identified.

[0067] Each of the first, second, third and / or fourth set of phases may comprise any number of phases. In some examples, each of the first, second, third and / or fourth set of phases comprise at least one phase.

[0068] Brief Description of the Drawings

[0069] Certain examples of the present disclosure will now be described with reference to the accompanying drawings in which:

[0070] Figure 1 is a schematic diagram of a multiphase power converter in accordance with an example of the present disclosure;

[0071] Figure 2 is a schematic diagram showing the power flow through a multiphase power converter in accordance with an example of the present disclosure;

[0072] Figure 3 is a schematic diagram of a system comprising a multiphase power converter and a controller in accordance with an example of the present disclosure;

[0073] Figure 4 is a schematic diagram showing the power flow through a system comprising a multiphase power converter and a controller in accordance with an example of the present disclosure;

[0074] Figure 5 is a schematic diagram of a multiphase power converter in accordance with an example of the present disclosure;

[0075] Figure 6 is a schematic diagram showing the power flow through a multiphase power converter in accordance with an example of the present disclosure; Figure 7 is a schematic diagram showing the power flow through a multiphase power converter in accordance with an example of the present disclosure;

[0076] Figure 8 is a schematic diagram showing the power flow through a multiphase power converter in accordance with an example of the present disclosure;

[0077] Figure 9 is a flow diagram showing a method of controlling a multiphase power converter in accordance with an example of the present disclosure;

[0078] Figure 10 is a flow diagram showing a method of controlling a multiphase power converter in accordance with an example of the present disclosure; and

[0079] Figures 11a and 11b are schematic diagrams showing the power flow through a multiphase power converter that includes four sets of phases in accordance with an example of the present disclosure.

[0080] Detailed

[0081] Figure 1 is a schematic diagram of a multiphase power converter 2 according to an example of the present disclosure.

[0082] The multiphase power converter 2 of this example includes a first phase 4a and a second phase 4b. Each of the first phase 4a and the second phase 4b includes a bidirectional power converter 6a, 6b, a first side 8a, 8b and a second side 10a, 10b. The first sides 8a, 8b of the first phase 4a and the second phase 4b are connected together at a first node 12 and the second sides 10a, 10b of the first phase 4a and the second phase 4b are connected together at a second node 14.

[0083] In this example, the first side 8a of the first phase 4a may be understood as the path between the first node 12 and the input of the bidirectional power converter 6a The second side 10a of the first phase 4a may be understood as the path between the output of the bidirectional power converter 6a and the second node 14. The second side 10b of the second phase 4b may be understood as the path between the second node 14 and the input of the bidirectional power converter 6b. The first side 8b of the second phase 4b may be understood as the path between the output of the bidirectional power converter 6b and the first node 12. The method of the present disclosure includes a simultaneous control step for controlling the multiphase power converter 2. This step includes controlling the first phase 4a of the multiphase power converter 2 such that power flows from the first side 8a of the first phase 4a to the second side 10a of the first phase 4a. At the same time (i.e. simultaneously), the second phase 4b of the multiphase power converter 2 is controlled such that power flows from the second side 10b of the second phase 4b to the first side 8b of the second phase 4b. In Figure 1 , the direction of power flow in each phase is indicated by the arrows.

[0084] It can be seen in Figure 1 that the power flow forms a loop through the multiphase power converter 2. That is, the power flowing from the second side 10a of the first phase 4a flows into the second side 10b of the second phase 4b, and the power flowing from the first side 8b of the second phase 4b flows into the first side 8a of the first phase 4a. This will be discussed in more detail below.

[0085] As the bidirectional power converters 6a, 6b are configured to allow power to flow in both directions, it will be understood that the power may flow in the opposite direction through each phase from that shown in Figure 1.

[0086] Figure 2 is a schematic diagram showing the power flow through a multiphase power converter 2 according to an example of the present disclosure. The multiphase power converter 2 of Figure 2 is similar to that of Figure 1. In this example, the multiphase power converter 2 is connected to a power source 16 at the first node 12 and a power sink 18 at the second node 14.

[0087] The power flowing on the first side 8a of the first phase 4a is denoted by P1. The power flowing on the second side 10a of the first phase 4a is denoted by P2. P2 may be different from P1, for example due to loss of power across the bidirectional power converter 6a of the first phase 4a (e.g. power dissipation as heat).

[0088] In this example, the power flowing on the second side 10b of the second phase 4b is denoted by P2 and is substantially equal to the power flowing on the second side 10a of the first phase 4a. Therefore, in this example no power is supplied to the power sink 18 (as denoted indicated by the ‘0’ next to power sink 18). Substantially all of the power flows directly from the second side 10a of the first phase 4a to the second side 10b of the second phase 4b. The advantages of this will be discussed further below.

[0089] The power flowing on the first side 8b of the second phase 4b is denoted by P3. P3 may be different from P2 due to loss of power across the bidirectional power converter 6b of the second phase 4b (e.g. dissipation as heat).

[0090] Owing to loss of power across the two bidirectional power converters 6a, 6b, the power source 16 is required to supply power equal to the difference between P1 and P3. This ensures that the power is able to flow in a loop through the first phase 4a and the second phase 4b. However, as no power is supplied to the power sink 18, the only substantial power loss in the multiphase power converter 2 is the loss of power across the two bidirectional power converters 6a, 6b. Bidirectional power converters generally have high efficiency (e.g. in excess of 90%). Hence, the power required from the power source 16 may be an order of magnitude smaller than the power flowing in the loop through the first phase 4a and the second phase 4b.

[0091] In one example, which is provided here purely to illustrate the operation and not to be construed in any limiting way whatsoever, the value of P1 is 10 W and the two bidirectional power converters 6a, 6b each have an efficiency of 95%. P2 therefore has a value of 9.5 W, owing to 5% of the power being lost across the bidirectional power converter 6a in the first phase 4a. P3 has a value of 9.025W, owing to another 5% of the power being lost across the bidirectional power converter 6b in the second phase 4b. However, the power source 16 is only required to deliver 0.975 W of power to the circuit (i.e. approximately 10% of the power circulating in the multiphase power converter 2). This allows the performance of one or more of the phases 4a, 4b to be tested at the desired operating power, while a much lower power is supplied to the multiphase power converter 2.

[0092] Hence, the method and system according to the present disclosure may help to ensure that testing of the multiphase power converter can be carried out using a small amount of power (much smaller than the full operating power). This may be particularly advantageous for multiphase power converters as they are often used in systems with high current and / or high power requirements such as in electric vehicles. Reducing the power required for testing may allow the multiphase power converter to be tested more easily, more frequently and / or more conveniently. By testing the multiphase power converter more frequently, issues with the performance may be identified and addressed more quickly, thereby helping to facilitate performance improvements compared to a system that is tested less frequently.

[0093] Furthermore, the method and system according to the present disclosure may allow the multiphase power converter to be tested without being disconnected from the power source and power sink and without any further equipment being required for testing. The (typically small) amount of power required for testing may be provided by the power source. This power circulates internally from one phase to another in order to perform tests. This may be particularly advantageous when the multiphase power converter is part of a larger system and / or a product, whereby removing the multiphase power converter for testing is time consuming and inconvenient. Being able to test the multiphase power converter without disconnecting it from the power source and power sink may allow the multiphase power converter to be tested more easily, more frequently and / or more conveniently. As set out above, this can help to improve or maintain the performance of the system.

[0094] Furthermore, the method and system according to the present disclosure may allow the multiphase power converter to be tested during operation. That is, the multiphase power converter may be tested while it continues to supply power to a power sink or load. Being able to test the multiphase power converter while the multiphase power converter is operational allows the multiphase power converter to be tested more easily, more frequently and / or more conveniently. As set out above, this may help to improve or maintain the performance of the system.

[0095] Figure 3 is a schematic diagram of a system comprising a multiphase power converter 2 and a controller 20 according to an example of the present disclosure.

[0096] The controller 20 is in communication with the first phase 4a via a first connection 24a and in communication with the second phase 4b via a second connection 24b. The first and second connections 24a, 24b may be any type (e.g. wired or wireless connections). The controller 20 is configured to send control signals to each of the first and second phases 4a, 4b via the first and second connections 24a, 24b respectively.

[0097] In some examples, the controller 20 may send different control signals to each of the first and second phases 4a, 4b. For example, the controller 20 may send a command to the first phase 4a to provide a particular voltage and the controller may send a command to the second phase 4b to provide a particular current. In other words, the first phase 4a is operated in a voltage control mode and the second phase 4b is operated in a current control mode.

[0098] Controlling one phase to provide a particular voltage (voltage control mode) and another phase to provide a particular current (current control mode) allows the two phases to self-regulate with respect to one another. This may be particularly advantageous if no power is being provided to a power sink, i.e. such that the power flowing on the second side of the first phase is substantially equal to the power flowing on the second side of the second phase.

[0099] In the example set out above, the first phase 4a may be configured to regulate its current in order to provide the particular voltage as commanded by the controller 20, and the second phase 4b may be configured to regulate its output voltage (voltage on its first side) in order to provide the particular current as commanded by the controller 20. As no power is drawn by the load (power sink), the power flowing out of the second side of the first phase is substantially equal to the power flowing in to the second side of the second phase.

[0100] In this example, the controller 20 is connected to the second node 14 via monitoring means 22. The monitoring means 22 is configured to measure and / or determine a parameter representative of an output of the multiphase power converter 2. For example, the monitoring means 22 may be configured to measure and / or determine the current, the voltage and / or the power at an output of the multiphase power converter 2.

[0101] The monitoring means 22 is configured to provide this information to the controller 20. The controller 20 may adjust the control signals that it provides to the first and / or second phases 4a, 4b according to the information it receives from the monitoring means 22. For example, if the monitoring means 22 determines that the power is lower than intended, the controller 20 may increase the particular current and / or voltage that it commands in its control signal. Hence, the monitoring means 22 and the controller 20 may be configured to operate as a feedback loop. This may help to ensure that the multiphase power converter 2 is operating as intended.

[0102] Figure 4 is a schematic diagram showing the power flow through a system comprising a multiphase power converter 2 and a controller 20 according to an example of the present disclosure. In this example, the multiphase power converter 2 is connected to a power source 16 at the first node 12 and a power sink 18 at the second node 14.

[0103] The controller 20 is configured to send control signals to the first phase 4a via a first connection 24a and the controller 20 is configured to send control signals to the second phase 4b via a second connection 24b, as in Figure 3. In this example, the controller 20 is also configured to receive feedback from the first phase 4a via a third connection 26a and the controller 20 is configured to receive feedback from the second phase 4b via a fourth connection 26b. In this example, each of the first and second phases 4a, 4b may be configured to measure and / or determine a parameter representative of the performance of the first and second phases 4a, 4b respectively. Each of the first and second phases 4a, 4b is configured to provide this information to the controller 20 via the third and fourth connections 26a, 26b respectively. The controller 20 may adjust the control signals that it provides to the first and / or second phases 4a, 4b according to this information. Hence, the first and second phases 4a, 4b themselves may provide a similar function to the monitoring means 22 of Figure 3 (e.g. forming a feedback loop). In some examples, the controller 20 receives feedback from a monitoring means 22 (e.g. as shown in Figure 3) and from one or more of the phases 4a, 4b (e.g. as shown in Figure 4). Thus the connections 24a, 24b, 26a, 26b may be used in conjunction with the monitoring means 22 in some examples.

[0104] Although the first, second, third and fourth connections 24a, 24b, 26a, 26b are shown separately, it will be understood that one or more may be formed from the same (e.g. physical) connection, e.g. communications may be sent and received over the same wire or over the same wireless connection. Figure 5 is a schematic diagram of a multiphase power converter 2 according to an example of the present disclosure. The multiphase power converter 2 of this example is similar to those shown in Figures 1 to 4. In this example, the multiphase power converter 2 further includes a third phase 4c and a fourth phase 4d. The third phase 4c and fourth phase 4d each include a bidirectional power converter 6c, 6d, a first side 8c, 8d and a second side 10c, 10d.

[0105] The first sides 8a-d of the first, second, third and fourth phases 4a-d are connected together at the first node 12. The second sides 10a-d of the first, second, third and fourth phases 4a-d are connected together at the second node 14.

[0106] In this example, the third phase 4c is controlled simultaneously with the first phase 4a such that power flows from the first side 8c of the third phase 4c to the second side 10c of the third phase 4c. The fourth phase 4d is controlled simultaneously with the second phase 4b such that power flows from the second side 10d of the fourth phase 4d to the first side 8d of the fourth phase 4d.

[0107] In this manner, the power flow through the multiphase power converter forms a loop, as in the previous examples. However, in this example, the power flow in each direction is split between two phases. In this way, a greater number of phases can be tested at one time, which may help to decrease the time required to test the multiphase power converter.

[0108] This may also help to increase the flexibility and / or control to perform certain tests. For example, the power flowing through a particular phase may be reduced or prevented altogether without preventing power from flowing in a loop through the multiphase power converter (as there are other phases available through which power may flow in the direction required to form the loop).

[0109] Figure 6 is a schematic diagram showing the power flow through a multiphase power converter 2 according to an example of the present disclosure. The multiphase power converter 2 of Figure 6 is similar to that of Figure 5. In this example, the multiphase power converter 2 is connected to a power source 16 at the first node 12 and a power sink 18 at the second node 14. The power through the first and second sides of each phase of the multiphase power converter 2 is denoted by P1-P8 respectively, in a similar manner to Figure 2. As in the example of Figure 2, the power on the respective first and second sides of each phase may be different due to loss of power across the bidirectional power converter of each respective phase (e.g. by dissipation as heat).

[0110] The power provided by the power source 16 is equal to P1-P4+P5-P8. The power provided to the power sink 18 is equal to P2-P3+P6-P7. It can therefore be seen that a multiphase power converter 2 including a greater number of phases may provide a greater degree of flexibility to select the power flowing through each phase, because there are more phases to compensate in order to meet the power requirement(s) of the power source 16 and / or the power sink 18. As in the previous examples, the power to the load (power sink 18) may be zero such that P2+P6 = P3+P7.

[0111] Figure 7 is a schematic diagram showing the power flow through a multiphase power converter 2 according to an example of the present disclosure. In this example, each of the bidirectional power converters 6a-d has an efficiency of 98%.

[0112] In this example, no power is provided to the power sink 18. The power flowing through the first, second and third phases 4a-c forms a loop. In this example, the power flowing through the second side 10a of the first phase 4a is split evenly between the second sides 10b, 10c of the second and third phases 4b, 4c respectively. As both the second and third phases 4b, 4c have power flow in the same direction, this provides a greater degree of flexibility over the power flowing through each phase. This allows enhanced testing of one or more phases of the multiphase power converter. In this example, the second and third phases 4b, 4c are tested at a lower power than the first phase 4a. It will be appreciated that the power flowing through the second and third phases 4b, 4c may be split evenly or unevenly.

[0113] As power is flowing through the first, second and third phases 4a-c, one or more of these phases may undergo testing. As discussed in relation to Figure 2, the power provided by the power source 16 is much lower than the power circulating in the multiphase power converter 2.

[0114] In this example, no power is flowing through the fourth phase 4d. The fourth phase 4d may be commanded to block power flowing through it. Such an arrangement may be useful when it is deemed unnecessary to test a particular phase of the multiphase power converter. It may also be determined (e.g. through testing) that a particular phase is not performing adequately and that it should be taken out of use. Alternatively, one phase may be taken out of use to reduce the power required to operate and / or test the multiphase power source (as no losses are incurred when it is off). Example values of power are also marked on this figure, purely as a means of illustrating the power flows, but without any limitation on the actual power capabilities of the devices.

[0115] Figure 8 is a schematic diagram showing the power flow through a multiphase power converter 2 according to an example of the present disclosure. In this example, each of the bidirectional power converters 6a-d has an efficiency of 96%.

[0116] In this example, the power sink 18 receives some power from the second node 14. At the same time, the first and second phases 4a, 4b are controlled such that the power flowing on the second side 10a of the first phase 6a is substantially the same as the power flowing on the second side 10b of the second phase 6b. The third and fourth phases 4c, 4d are controlled such that the power flowing on the second side 10c, 10d of each of the third and fourth phases 4c, 4d maintains the power for the power sink 18.

[0117] The power flowing through the first and second phases 4a, 4b forms a loop as discussed above. One or both of the first and second phases 4a, 4b may thus be measured and / or tested for performance. The direction of power flow through the first and second phases 4a, 4b can also be reversed so as to test them in the opposite direction without impacting the provision of power to the load 18 via the third and fourth phases 4c, 4d.

[0118] In this example, the power source 16 provides a higher power to the multiphase power converter 2 than in some previous examples because power is being provided to the power sink 18 in addition to the power required to compensate for the losses in the first and second converters 6a, 6b. However, as has been discussed in relation to the previous example, the extra power provided for testing of the first and / or second phases 4a, 4b is still an order of magnitude smaller than the power flowing through these phases. Example values of power are also marked on this figure, purely as a means of illustrating the power flows, but without any limitation on the actual power capabilities of the devices.

[0119] Figure 9 is a flow diagram showing a method of controlling a multiphase power converter according to an example of the present disclosure.

[0120] The method includes the steps of: selecting a first phase and a second phase (step 101); simultaneously controlling the power flow through the first phase in a first direction and through the second phase in the opposite direction (step 102); performing at least one test operation on at least one of the first and second phases (step 103); simultaneously controlling the first and second phases to reverse the power flow through the first and second phases (step 104) and performing at least one test operation on at least one of the first and second phases (step 105).

[0121] The first and second phases may be selected in any manner in step 101. For example, phases may be selected based on when they were last tested, the results of previous tests and / or according to a predetermined order.

[0122] In step 102, the first direction may be from the first side (of the first phase) to the second side (of the first phase). Therefore, the second direction (being the reversed direction of step 104) may be from the second side (of the second phase) to the first side (of the second phase).

[0123] Reversing the direction of the power flow in step 104 may help to ensure that both the first and second phases have been tested while power flows in both directions through the phases. This can help to determine for example whether the performance of the phase is substantially the same when power flows in each direction through the phase and / or it can help to determine if the performance of the two phases are sufficiently similar (if the phases have the same hardware then they any significant discrepancies may indicate a problem with one of the phases). The tests performed in steps 103 and 105 may be any type of test. The tests may be performed on either or both of the first and second phases. The tests may be the same or different in each step and / or for each of the first and second phases.

[0124] The method includes the optional step 106 of repeating the steps of the method. The method may be repeated as often as necessary or desired. For example, the method may be carried out each time that the multiphase power converter is in the power-up stage (e.g. shortly after the multiphase power converter is switched on). In some examples, the method may be repeated after a predetermined period of time has elapsed. Repeating the steps of the method allows the phases of the multiphase power converter to be tested more regularly.

[0125] Figure 10 is a flow diagram showing a method of controlling a multiphase power converter according to an example of the present disclosure.

[0126] The method includes the steps of: selecting, from at least three phases, a first phase and a second phase (step 201); simultaneously controlling the power flow through the first phase in a first direction and through the second phase in the opposite direction (step 202); performing at least one test operation on at least one of the first and second phases (step 203) and selecting, from the at least three phases, at least a first phase and a second phase that is a different combination or permutation of the at least three phases for the first phase and the second phase (step 204).

[0127] The first and second phases may be selected in any manner in step 201. For example, phases may be selected based on when they were last tested, the results of previous tests and / or according to a predetermined order.

[0128] In step 202, the first direction may be from the first side (of the first phase) to the second side (of the first phase). Therefore, the second direction (opposite to the first direction) may be from the second side (of the second phase) to the first side (of the second phase). The tests performed in step 203 may be any type of test. The tests may be performed on either or both of the first and second phases. If tests are performed on both the first and second phases, the tests may be the same or different for each of the first and second phases.

[0129] In step 204, the different combination or permutation of the first and second phases may be selected in any manner. For example, phases may be selected based on when they were last tested, the results of previous tests and / or according to a predetermined order. Selecting a different combination or permutation of the first and second phases may help to ensure that all of the phases of the multiphase power converter are tested.

[0130] The method includes the optional step 205 of repeating steps 202, 203 and 204 of the method. Steps 202, 203 and 204 of the method may be repeated as often as necessary or desired. For example, steps 202, 203 and 204 of the method may be repeated until all of the phases of the multiphase power converter have been tested.

[0131] Figures 11a and 11b are schematic diagrams showing the power flow through a multiphase power converter 2 that includes four sets of phases 28, 30, 32, 34 according to an example of the present disclosure.

[0132] In this example, the multiphase power converter 2 includes four sets of phases 28, 30, 32, 34. Each set of phases 28, 30, 32, 34 may include any number of phases. Each set of phases 28, 30, 32, 34 is controlled as a group such that power flows in the same direction through each phase in a given set of phases.

[0133] For example, Figure 11 b is an expanded view of the first phase 28. It can be seen that the first set of phases 28 includes three phases 4e, 4f, 4g. Each of the three phases 4e, 4f, 4g in the first set of phases 28 is similar to the phases discussed in relation to Figures 1 to 8. Although in this example, the first set of phases 28 includes three phases 4e, 4f, 4g, it will be understood that each set of phases can include any number of phases. In this example, the first set of phases 28 is controlled such that power flows from the first side 8e, 8f, 8g to the second side 10e, 10f, 10g of each phase 4e, 4f, 4g in the first set of phases 28. The second set of phases 30 is controlled such that power flows from the second side to the first side of each phase in the second set of phases. Therefore, as set out above in relation to the other figures, the power flowing through the first and second sets of phases 28, 30 forms a loop. The power flowing through the first and second sets of phases 28, 30 can be used to facilitate testing of the first and second sets of phases 28, 30.

[0134] In this example, the third set of phases 32 is controlled in order to supply power to the power sink 18 in accordance with a power demand from the power sink 18. The power flowing on the second side of the third set of phases 32 can maintain the power for the power sink 18.

[0135] In this example, the fourth set of phases 34 is controlled to block power flowing through each phase in the fourth set of phases 34. Such an arrangement may be useful when it is deemed unnecessary to test a particular set of phases of the multiphase power converter. It may also be determined (e.g. through testing) that a particular set of phases is not performing adequately and that it should be taken out of use. Alternatively, one set of phases may be taken out of use to reduce the power required to operate and / or test the multiphase power source (as no losses are incurred when it is off).

[0136] It will be appreciated that the phases of a multiphase controller 2 may be grouped together into sets on a permanent basis (e.g. at design or manufacture stage) or they may be grouped into sets on a dynamic basis according to the needs of the system. In such examples, each phase may be moved from one set to another set if desired, e.g. to enable different testing or analysis techniques. Similarly, the number of sets of phases may be changed as required. It will also be appreciated that the different sets may have the same number of phases, but also each set may have a different number of phases.

Claims

Claims1. A method of controlling a multiphase power converter, wherein the multiphase power converter comprises a plurality of phases; wherein each of the plurality of phases comprises a bidirectional power converter; wherein each of the plurality of phases comprises a first side and a second side; wherein the first sides of the plurality of phases are connected together at a first node; wherein the second sides of the plurality of phases are connected together at a second node; and wherein the method comprises a simultaneous control step of simultaneously controlling: a first phase of the multiphase power converter such that power flows from the first side of the first phase to the second side of the first phase; and a second phase of the multiphase power converter such that power flows from the second side of the second phase to the first side of the second phase.

2. A method as claimed in claim 1 , wherein controlling the first phase of the multiphase power converter comprises controlling the first phase to provide a particular voltage.

3. A method as claimed in claim 1 or 2, wherein controlling the second phase of the multiphase power converter comprises controlling the second phase to provide a particular current.

4. A method as claimed in claim 1 , 2 or 3, wherein the method further comprises, for at least one phase, the steps of: measuring at least one characteristic of the phase; and determining a performance indicator of the phase from the measurement.

5. A method as claimed in claim 4, wherein the characteristic comprises one or more of:a voltage across the phase; a current through the phase; a temperature associated with the phase; and a duty cycle associated with the phase.

6. A method as claimed in any preceding claim, wherein the power flowing on the second side of the first phase is substantially equal in magnitude to the power flowing on the second side of the second phase.

7. A method as claimed in any preceding claim, wherein a power source is connected to the multiphase power converter at the first node; and wherein the method comprises the step of: controlling the power source to supply power to the multiphase power converter.

8. A method as claimed in claim 7, wherein the power supplied by the power source is equal to the difference between the power flowing on the first side of the first phase and the power flowing on the first side of the second phase.

9. A method as claimed in any preceding claim, wherein a power sink is connected to the multiphase power converter at the second node; and wherein the method comprises the step of: controlling the multiphase power converter to supply power to the power sink.

10. A method as claimed in any preceding claim, wherein the method further comprises the step of simultaneously controlling: the first phase of the multiphase power converter such that power flows from the second side of the first phase to the first side of the first phase; and the second phase of the multiphase power converter such that power flows from the first side of the second phase to the second side of the second phase.

11. A method as claimed in any preceding claim, wherein the steps of the method are carried out during a power-up stage of the multiphase power converter.

12. A method as claimed in any preceding claim, wherein the steps of the method are repeated after a predetermined interval of time has elapsed.

13. A method as claimed in any preceding claim, wherein: the multiphase power converter comprises a third phase; and wherein the third phase of the multiphase power converter is controlled simultaneously with the first phase such that power flows from the first side of the third phase to the second side of the third phase.

14. A method as claimed in any preceding claim, wherein: the multiphase power converter comprises a fourth phase; and wherein the fourth phase of the multiphase power converter is controlled simultaneously with the second phase such that power flows from the second side of the fourth phase to the first side of the fourth phase.

15. A method as claimed in any preceding claim, wherein the multiphase power converter comprises at least three phases; and wherein the method comprises a plurality of test operations, each test operation comprising: selecting one of the at least three phases as the first phase; selecting another of the at least three phases as the second phase; and performing the simultaneous control step for the selected first phase and the selected second phase; wherein each test operation selects a different combination or permutation of the at least three phases for the first phase and the second phase.

16. A system comprising: a multiphase power converter, wherein the multiphase power converter comprises a plurality of phases; wherein each of the plurality of phases comprises a bidirectional power converter; wherein each of the plurality of phases comprises a first side and a second side;wherein the first sides of the plurality of phases are connected together at a first node; wherein the second sides of the plurality of phases are connected together at a second node; and a controller configured to simultaneously control: a first phase of the multiphase power converter such that power flows from the first side of the first phase to the second side of the first phase; and a second phase of the multiphase power converter such that power flows from the second side of the second phase to the first side of the second phase.

17. A system as claimed in claim 16, wherein the system further comprises a power source connected to the multiphase power converter at the first node; and wherein the controller is configured to control the power source to supply power to the multiphase power converter.

18. A system as claimed in claim 17, wherein the power supplied by the power source is equal to the difference between the power flowing on the first side of the first phase and the power flowing on the first side of the second phase.

19. A system as claimed in claim 16, 17 or 18, wherein the system further comprises a power sink connected to the multiphase power converter at the second node; and wherein the controller is configured to control the multiphase power converter to supply power to the power sink.

20. A system as claimed in claim 19, wherein the multiphase power converter comprises more than two phases; and wherein the first and second phases do not contribute to the multiphase power converter supplying power to the sink.

21. A method of controlling a multiphase power converter, wherein the multiphase power converter comprises a plurality of phases; wherein each of the plurality of phases comprises a bidirectional power converter;wherein each of the plurality of phases comprises a first side and a second side; wherein the first sides of the plurality of phases are connected together at a first node; wherein the second sides of the plurality of phases are connected together at a second node; and wherein the method comprises the step of simultaneously: controlling a first set of phases of the multiphase power converter such that power flows from the first side to the second side of each phase in the first set of phases; controlling a second set of phases of the multiphase power converter such that power flows from the second side to the first side of each phase in the second set of phases.

22. A method as claimed in claim 21, wherein the method comprises controlling a third set of phases of the multiphase power converter to supply power to a power sink in accordance with a power demand from the power sink.

23. A method as claimed in claim 21 or 22, wherein the method comprises controlling a fourth set of phases of the multiphase power converter to block power flowing through each phase in the fourth set of phases.

24. A method as claimed in any of claims 21 , 22 or 23, wherein each of the first, second, third and / or fourth set of phases comprise at least one phase.

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