Power converters and modular power converters

Abstract

A power converter having a modular, compact architecture with a reduced component count is disclosed. The power converter includes parallel power conversion sections and utilizes one or more mutually coupled input inductors having multiple windings. The windings are connected in pairs in a differential mode between a power source and the parallel power conversion sections. Each power conversion section receives the same input voltage and produces the same output voltage. Due to the winding connections and the identical input and output voltages, the input of the power converter exhibits current balancing and sharing between each branch of the parallel configuration, thereby allowing a single current sensor to provide a measurement of the current and a single controller to control the operation of each of the power conversion sections.

Description

Background Art

[0001] The subject matter disclosed herein relates to a power converter having a modular, compact architecture with reduced component count. More specifically, the power converter includes parallel power conversion sections and utilizes one or more mutually coupled input inductors having multiple windings connected in pairs in a differential mode between a power source and the parallel power conversion sections, thereby producing current balancing and sharing between each branch of the parallel configuration.

[0002] As is known to those skilled in the art, a power converter allows a controlled output voltage and / or current to be supplied from an input power source. The input power source may be an alternating current (AC) or direct current (DC) voltage having a first amplitude and a first frequency. The output of the power converter may be an AC or DC voltage having a second amplitude and a second frequency, wherein the second amplitude and / or the second frequency are different from the first amplitude and / or the first frequency. Depending on the configuration of the power converter, the output of the power converter may be fixed or variable. Many configurations of one or more active or passive switching devices and inductive or capacitive devices are arranged to provide a controlled output voltage.

[0003] In order to convert the voltage from a first amplitude and a first frequency at the input to a second amplitude and a second frequency at the output, the power converter utilizes one or more power switching devices, such as thyristors, silicon-controlled rectifiers (SCRs), diodes, metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), other power transistors, and the like. The power switching devices can be active or passive, and a controller can generate switching signals to control the operation of the active devices. The switching devices are switched on and off at frequencies ranging from hundreds of hertz to hundreds of kilohertz to synthesize the desired output voltage from the input voltage.

[0004] However, switching the devices on and off creates an electrically noisy environment with undesirable conducted and / or radiated emissions. Undesirable conducted emissions include transient voltages and / or currents at the input and output of the power converter. In order to limit undesirable conducted emissions, a filter device may be connected at the input or output. As the power rating of the power converter increases, the switching devices and the filter devices must be sized accordingly. Increasing the power rating of the switching devices and / or filter devices typically results in increased costs, for example due to more expensive materials, increased size to handle the increased current capacity, or a combination thereof.

[0005] At high power levels, these devices may no longer be rated to handle the desired power, or the cost of devices that can be rated to handle the desired power is too high. Historically, these disadvantages have been overcome by providing multiple power conversion sections operating in parallel. Each power conversion section handles a portion of the system power, and therefore, the components of each section only need to be rated to handle a corresponding portion of the power.

[0006] However, such systems are not without drawbacks. Each power conversion section requires its own filters and switching devices, increasing the physical size of the system.

[0007] A first feature of the present invention is to provide a parallel power converter system having a reduced size.

[0008] Another feature of the present invention is to provide a parallel power converter system with reduced parts count, which in turn reduces cost and further reduces size.

[0009] It is also known to provide a separate controller to control each power conversion section. The controllers of each power conversion section must be synchronized to operate together and produce the desired output voltage. Synchronization requires communication between the controllers. As previously noted, the rapid switching of switching devices creates an electrically noisy environment. This electrical noise can cause communication errors between the controllers or require additional shielding to prevent errors.

[0010] Another feature of the present invention is to provide a parallel power converter system that does not require communication between the power conversion sections. Summary of the Invention

[0011] The subject matter disclosed herein describes a power converter having a modular, compact architecture with reduced component count and reduced size. The power converter includes parallel power conversion sections and utilizes one or more mutually coupled input inductors having multiple windings. The mutual windings are connected in pairs in a differential mode between the power supply and the parallel power conversion sections. Each power conversion section receives the same input voltage and produces the same output voltage. Due to the winding connection and the same input voltage and output voltage, the input of the power converter exhibits current balance and sharing between each section of the parallel configuration, thereby allowing a single current sensor to provide a measurement of the current. The current measurement is provided to a single controller, which generates a control signal for each power conversion section in the power conversion section. The single controller eliminates the need for communication between the power conversions.

[0012] According to one embodiment of the present invention, a power converter includes multiple power conversion sections, a mutual choke, a current sensor, and a controller. Each power conversion section includes an input and an output. The input is configured to receive a first voltage having a first amplitude and a first frequency, and the output is configured to deliver a second voltage having a second amplitude and a second frequency. The mutual choke includes a magnetic core, a first winding, and a second winding. The first winding on the magnetic core is connected in series between a power source and a first power conversion section selected from the plurality of power conversion sections. The second winding on the magnetic core is connected in series between the power source and a second power conversion section selected from the plurality of power conversion sections. The first winding is configured to conduct a first current, and the second winding is configured to conduct a second current. The first winding and the second winding are connected between the power source and the first and second power conversion sections, respectively, such that the first current flows in a direction opposite to the second current relative to the magnetic core. The current sensor is configured to generate a signal corresponding to the amplitude of the current entering the power conversion section. The controller is configured to receive a signal from the current sensor and, in response to the signal from the current sensor, generate a first set of control signals for the first power conversion section and a second set of control signals for the second power conversion section.

[0013] According to another embodiment of the present invention, a modular power converter includes at least one pair of power conversion sections, a mutual choke, a current sensor, and a controller. Each pair of power conversion sections includes a first power conversion section and a second power conversion section. The first power conversion section includes an input terminal configured to receive a first voltage having a first amplitude and a first frequency, and an output terminal configured to deliver a second voltage having a second amplitude and a second frequency. The second power conversion section includes an input terminal configured to receive the first voltage, and an output terminal configured to deliver the second voltage. The mutual choke includes a first winding electrically connected between a power source and the first power conversion section, and a second winding electrically connected between the power source and the second power conversion section. The first and second windings are electrically connected such that a first current in the first winding flows in an opposite direction to a second current in the second winding. The current sensor can be configured to generate a signal corresponding to the amplitude of the current provided to the first power conversion section, the second power conversion section, or a combination thereof. The controller may be used to receive the signal from the current sensor and generate a first set of control signals for the first power conversion section and a second set of control signals for the second power conversion section in response to the signal from the current sensor.

[0014] According to another embodiment of the present invention, a modular power converter includes at least one pair of power conversion sections, at least one mutual choke, a current sensor, and a controller. Each pair of power conversion sections can be configured to receive a first voltage having a first amplitude and a first frequency, and an output terminal can be configured to deliver a second voltage having a second amplitude and a second frequency. Each choke includes at least one pair of windings connected in a differential mode, and each pair of windings is configured to be connected between a power source that can be used to provide the first voltage and a pair of power conversion sections in the power conversion section. The current sensor can be configured to generate a signal corresponding to the amplitude of the current provided to the modular power converter, and the controller can be configured to receive the signal from the current sensor and generate a set of control signals for each pair of power conversion sections in response to the signal from the current sensor.

[0015] These and other objects, advantages, and features of the present invention will be readily apparent to those skilled in the art from the detailed description and accompanying drawings. However, it should be understood that the detailed description and accompanying drawings, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Numerous changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the present invention includes all such modifications. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Various exemplary embodiments of the subject matter disclosed herein are illustrated in the accompanying drawings, wherein like reference numerals refer to like parts throughout, and in which:

[0017] Figure 1 is a schematic representation of an exemplary power converter incorporating mutually coupled input inductors for a pair of branches in the power converter according to one embodiment of the present invention;

[0018] Figure 2 is a schematic representation of an exemplary power converter incorporating mutually coupled input inductors for a pair of branches in the power converter according to another embodiment of the present invention;

[0019] Figure 3 is a schematic representation of an exemplary power converter incorporating modular mutually coupled input inductors for current sharing between two pairs of branches in the power converter according to another embodiment of the present invention;

[0020] Figure 4 is a schematic representation of an exemplary power converter incorporating mutually coupled input inductors for two pairs of branches in the power converter according to another embodiment of the present invention;

[0021] Figure 5is a schematic representation of an exemplary power converter incorporating a modular mutually coupled input inductor and a multi-phase alternating current (AC) power source for current sharing among four branches of the power converter according to another embodiment of the present invention;

[0022] Figure 6 is a schematic representation of an exemplary power converter incorporating a modular mutually coupled input inductor and a multi-phase alternating current (AC) power source for current sharing among four branches of the power converter according to another embodiment of the present invention;

[0023] Figure 7 is a schematic representation of an exemplary power converter having a multi-phase AC power source incorporating a plurality of mutually coupled input inductors and four branches, wherein each inductor corresponds to a phase of the AC power source, in accordance with another embodiment of the present invention; and

[0024] Figure 8 yes Figure 1 A block diagram representation of one embodiment of a controller; and

[0025] Figure 9 is a representative illustration of a choke with multiple windings wrapped around a common core.

[0026] In describing the preferred embodiments of the present invention shown in the drawings, specific terminology will be used for the sake of clarity. However, the present invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to achieve a similar purpose. For example, the words "connected," "attached," or similar terms are generally used. These are not limited to direct connections, but include connections through other elements where those skilled in the art recognize such connections as equivalent. DETAILED DESCRIPTION

[0027] Various features and advantageous details of the subject matter disclosed herein are more fully explained with reference to the non-limiting examples described in detail in the following description.

[0028] First go to Figure 1 , shows a power converter 10 according to one embodiment of the present invention. The power converter 10 includes a first power conversion section 12a and a second power conversion section 12b. Each of the first power conversion section and the second power conversion section is connected in parallel between a power source 35 and an output terminal 70. According to the embodiment shown, the power source 35 is a direct current (DC) power source, thereby supplying a first DC voltage u 输入 The output 70 of the power converter 10 is a DC bus having a positive supply rail 72 and a negative supply rail 74, on which a second DC voltage DC is provided. 输出A first voltage u is provided as an input to the power converter 10 输入 has a first amplitude and a first frequency, wherein for a DC voltage, the frequency is zero Hertz (0 Hz). A second voltage DC is provided as an output from the power converter 10 输出 The power converter 10 has a second amplitude and a second frequency, wherein the frequency is zero hertz (0 Hz) for a DC voltage. It is contemplated that the power converter 10 may be a boost converter such that the second voltage is greater than the first voltage; a buck converter such that the second voltage is less than the first voltage; or a combination thereof, wherein the output voltage may vary according to application requirements and may be greater than or less than the input voltage.

[0029] The power converter 10 further includes a mutual choke 20 connected in series between the DC power source 35 and each of the power conversion sections. The mutual choke 20 is a single magnetic device that includes separate windings for each power conversion section wound on a single magnetic device. According to the embodiment shown, the first winding 22 is connected in series between the power source 35 and the first power conversion section 12a, and the second winding 24 is connected in series between the power source 35 and the second power conversion section 12b. Also refer to Figure 9 , an exemplary mutual choke 20 is shown. For ease of illustration and not intended to be limiting, the exemplary mutual choke 20 is shown with only four turns in each winding. Similarly, a square core 25 is shown for ease of illustration and not intended to be limiting. The shape of the core 25 or the number of turns per winding will be selected based on the application requirements to achieve the desired inductance in each of the windings 22, 24.

[0030] Each of the first and second windings 22, 24 is wound around a magnetic core 25 and connected in a differential mode between a power source 35 and power conversion sections 12a, 12b. In other words, current flows through each winding in opposite directions relative to the magnetic core 25. The first winding 22 includes a first end 26 and a second end 28, and the second winding 24 includes a first end 29 and a second end 27. Both the first and second windings 22, 24 are connected between the power source 35 and the respective power conversion sections 12a, 12b, such that current flows from the power source 35 to the respective power conversion sections 12a, 12b. However, the first end 26 of the first winding 22 begins at the second end 27 of the second winding 24, and both windings are wound around the magnetic core 25 of the mutual choke 20 such that the second end 28 of the first winding 22 is at the first end 29 of the second winding 24. A first current 21 flowing through the first winding 22 is conducted through the first winding 22 in a first direction. A second current 23 flowing through the second winding 24 is conducted through the second winding 24 in a second direction. The first direction is opposite to the second direction relative to the magnetic core 25 of the choke 20. Although each winding is shown as terminating near the magnetic core 25, this is for ease of illustration and to provide reference numbers in other figures. For example, it is contemplated that a single conductor may span between the power source 35 and one of the power conversion sections, with a portion of the single conductor wound around the magnetic core to define a winding.

[0031] The power converter 10 also includes a current sensor 40 that generates a signal 42 corresponding to the amplitude of the current at the input of the power converter 10. Figure 1 and Figure 2 , a single current sensor 40 is provided at some location on the input side of the power converter 10. The power converter shown includes two branches, wherein the first branch is at least partially defined by the first winding 22 and the first power conversion section 12a, and the second branch is at least partially defined by the second winding 24 and the second power conversion section 12b. A common or shared electrical conductor is connected between the power supply 35 and the two branches. Figure 1 In FIG, a current sensor 40 is shown as being operatively connected to a common electrical conductor. Figure 2 , current sensor 40 is shown as being operatively connected in the first branch. In either position, a signal 42 generated by current sensor 40 is provided to a controller 50 of power converter 10.

[0032] The controller 50 is used to control the operation of each power conversion section 12 in the power converter 10. Figure 8The controller 50 includes a non-transitive memory 52 for storing a series of instructions for execution on a processor 54. It is contemplated that the processor 54 may be a single processor or a plurality of processors executing in parallel or asynchronously. The controller 50 also includes a feedback circuit 56 configured to receive a current feedback signal i fdbk 61a and voltage feedback signal v fdbk 61b, and provides feedback signals 61a, 61b to processor 54. Processor 54 is used to execute stored instructions to generate control signals CTL1 and CTL2 for each power conversion section 12. The control signal is transmitted from output terminal 64 of controller 50 to each power conversion section 12 via driver circuit 58.

[0033] Figure 1 and Figure 2 The embodiment of the power converter 10 shown in FIG includes a single pair of power conversion sections 12 and a single mutual choke 20. A pair of power conversion sections 12 and chokes can be replicated in a modular manner to increase the capacity of the power converter 10. Figure 3 and Figure 4 , shows an additional embodiment of a power converter 10 having multiple pairs of power conversion sections 12 and multiple chokes 20.

[0034] First reference Figure 3, the power converter 10 includes four power conversion sections 12a, 12b, 12c, 12d. The power conversion sections 12a, 12b, 12c, 12d are provided in pairs. Although shown as two pairs, it is contemplated that the power conversion sections 12a, 12b, 12c, 12d may be provided in various other numbers of paired sections depending on application requirements. The first power conversion section 12a and the second power conversion section 12b define a first pair of power conversion sections, and the third power conversion section 12c and the fourth power conversion section 12d define a second pair of power conversion sections. The first choke 20a includes a pair of windings 22a, 24a connected to the first pair of power conversion sections 12a, 12b in a differential mode. The second choke 20b includes a second pair of windings 22b, 24b connected to the second pair of power conversion sections 12c, 12d in a differential mode. A third choke coil 20c is also provided between the power supply 35 and each of the first and second choke coils 20a and 20b. The third choke coil 20c includes a third pair of windings 22c and 24c, wherein the third pair of windings is differentially connected to the first and second choke coils. Thus, the third choke coil 20c first divides the current from the power supply 35 into a first current 21c and a second current 23c. Each of the first and second currents 21c and 23c in the third choke coil 20c is further divided into two additional branches at the first and second choke coils 20a and 20b.

[0035] The controller 50 receives a single current feedback signal 61a from the current sensor 40 at the input of the power converter 10 and generates four sets of control signals 65, 67, 69, and 71. A first set of control signals 65 is sent from the controller 50 to the first power conversion section 12a. A second set of control signals 67 is sent from the controller 50 to the second power conversion section 12b. A third set of control signals 69 is sent from the controller 50 to the third power conversion section 12c. A fourth set of control signals 71 is sent from the controller 50 to the fourth power conversion section 12d. The outputs of each power conversion section are connected in parallel and provided to a DC bus 70 at the output of the power converter 10.

[0036] Next reference Figure 4, shows another embodiment of the present invention including four power conversion sections 12a, 12b, 12c, and 12d. The power conversion sections 12a, 12b, 12c, and 12d are again provided in pairs. The first power conversion section 12a and the second power conversion section 12b define a first pair of power conversion sections, and the third power conversion section 12c and the fourth power conversion section 12d define a second pair of power conversion sections. A mutual choke 100 is provided with windings for all four power conversion sections 12a, 12b, 12c, and 12d wound on a common magnetic core. A first winding 102 and a second winding 104 are connected to the first pair of power conversion sections 12a and 12b in a differential mode. A third winding 106 and a fourth winding 108 are connected to the second pair of power conversion sections 12c and 12d in a differential mode. As shown in the figure, the current from the power supply 35 is first divided into a first current 99 and a second current 97, each of which is provided to a pair of windings. The first current 99 is split into two additional currents 101, 105, each of which is conducted through one of the windings 102, 106 on the choke 100, and the second current 97 is split into two additional currents 103, 107, each of which is conducted through one of the windings 104, 108 on the choke 100. Alternatively, it is contemplated that the windings may be connected directly to the power source 35 at a single connection point. The outputs of each power conversion section 12 are connected in parallel and provided to the DC bus 70 at the output of the power converter 10.

[0037] Then turn Figure 5 , shows an exemplary power converter 10 configured to receive an alternating current (AC) voltage from a power source 35. The power source shown includes four individual or two pairs of power conversion sections. Figure 1 and Figure 2 In the power converter 10 for a DC power supply shown in FIG, it is contemplated that the power converter 10 may include a single pair of power conversion sections. Alternatively, more than two pairs of power conversion sections may be provided depending on application requirements. The first power conversion section 12 a and the second power conversion section 12 b define a first pair of power conversion sections, and the third power conversion section 12 c and the fourth power conversion section 12 d define a second pair of power conversion sections.

[0038] According to the illustrated embodiment, AC power source 35 provides a three-phase voltage from a utility grid. A separate choke is provided for each phase of the voltage. Thus, single-phase AC voltage utilizes a single choke, while multi-phase voltages with a different number of phases utilize a single choke for each phase. As shown, a first set of three chokes is provided between the three-phase voltage and the first pair of power conversion sections. A first choke 20a, comprising a pair of windings, is connected in differential mode for the first phase of the three-phase voltage supplied to the first pair of power conversion sections 12a, 12b. A second choke 20b, comprising a pair of windings, is connected in differential mode for the second phase of the three-phase voltage supplied to the first pair of power conversion sections 12a, 12b. A third choke 20c, comprising a pair of windings, is connected in differential mode for the third phase of the three-phase voltage supplied to the first pair of power conversion sections 12a, 12b. Similarly, a second set of three chokes is provided between the three-phase voltage and the second pair of power conversion sections. Three chokes 20d, 20e, and 20f, each comprising a pair of windings, are connected to each of the three phases supplied to the second pair of power conversion sections 12c and 12d. A third set of chokes is provided between the power supply 35 and each of the first and second sets of chokes. Each of the three chokes 20g, 20h, and 20i in the third set comprises a pair of windings and is connected in differential mode to one of the three phases of the three-phase voltage between the power supply 35 and each of the first and second sets of chokes.

[0039] The controller 50 receives a current feedback signal 61a from a current sensor 40 present on each phase of the input. As shown, a first current sensor 40a is located on the first phase, a second current sensor 40b is located on the second phase, and a third current sensor 40c is located on the third phase. Each of the current sensors 40a, 40b, 40c generates a signal corresponding to the amplitude of the current present in that phase, and the signals are provided as inputs to the controller 50. The controller generates a set of control signals 66 that are used to control the operation of each power conversion section based on the current feedback signals. Figure 5 As shown, the current sensor 40 can be located before any branch in the power converter 10 and provide a signal corresponding to the total current input to the power converter 10. Figure 6 As shown, it is also contemplated that the current sensor 40 may be located in one of the branches, at an intermediate location as shown, or in the final branch connected to one of the power conversion sections 12. The signal generated by the current sensor 40 would then correspond to the amplitude of the current at the location along the branch where the current sensor is installed.

[0040] Next reference Figure 7, shows another embodiment of the present invention including four power conversion sections 12 for an AC power source 35. The power conversion sections 12 are again provided in pairs. A first power conversion section 12a and a second power conversion section 12b define a first pair of power conversion sections, and a third power conversion section 12c and a fourth power conversion section 12d define a second pair of power conversion sections. A set of mutual chokes 100 is provided for each phase of the AC power source. First choke 100a is provided for the first phase and includes four windings. First winding 102 and second winding 104 are connected as a first pair in a differential connection between the power source 35 and the first phase input terminals for the first power conversion section 12a and the first phase input terminals for the second power conversion section 12b. Third winding 106 and fourth winding 108 are connected as a second pair in a differential connection between the power source 35 and the first phase input terminals for the third power conversion section 12c and the first phase input terminals for the fourth power conversion section 12d. A second choke 100b and a third choke 100c are also provided for the second and third phases, respectively. Each of the second choke 100b and the third choke 100c further includes four windings. The four windings are connected in differential pairs to connect the respective phases of the power supply 35 to the corresponding phase input terminals in each of the power conversion sections 12.

[0041] Figures 5 to 7 The output of each of the power converters shown in FIG is provided at a DC bus 70. The DC bus 70 shown includes multiple DC voltages. Each power conversion section 12 includes a set of diodes to rectify the AC voltage. The rectified AC voltage is output as a DC voltage that is substantially equal to the peak-to-peak value of the AC input voltage between the positive supply rail 72 and the negative supply rail 74 of the DC bus. A set of transistors are connected in pairs for each phase of the input voltage to provide a third voltage at the middle supply rail 73 of the DC bus.

[0042] In operation, the power converter 10 is used to convert a first voltage having a first amplitude and a first frequency into a second voltage having a second amplitude and a second frequency. Figures 1 to 4 As shown, the power converter 10 converts a first DC voltage received at the input of the power converter 10 into a second DC voltage present at the output 70 of the power converter. Figures 5 to 7 As shown, the power converter 10 converts an AC voltage received at the input of the power converter 10 to a DC voltage present at the output 70 of the power converter. The illustrated embodiment illustrates both DC to DC power conversion and AC to DC power conversion. It is further contemplated that the modular architecture described herein may be similarly applied to DC to AC power conversion or AC to AC power conversion without departing from the scope of the present invention.

[0043] Power converter 10 utilizes paired power conversion sections to achieve a reduced size compared to standard power converters. The paired power conversion sections are coupled with a shared magnetic device, such as a choke 20, at the input ends of the two power conversion sections. The configuration of the power conversion sections 12 and each winding 22, 24 on the choke 20 is identical, so that the electrical properties of each branch in power converter 10 are identical. As used herein, a branch of power converter 10 includes one power conversion section and one winding 22, 24 in a pair of windings on the choke 20 for the DC input. A branch includes one power conversion section and one winding 22, 24 in each pair of windings on the choke 20 for each phase of the AC input. The configuration of the shared magnetic device and paired power conversion sections creates a natural current balance between the branches of power converter 10. Therefore, the current flowing in each branch of power converter 10 is substantially the same, although it should be understood that there will be slight variations in the current amplitude due to, for example, manufacturing and component tolerances.

[0044] As described above, the paired windings 22, 24 on each magnetic core 25 are connected in a differential manner between the input and output terminals of the choke 20. The differential connection of the windings 22, 24 serves to cancel at least a portion of the flux generated in the magnetic core 25 of the magnetic device 20. The current flowing through each winding 22, 24 on the choke 20 generates a magnetic flux that is conducted within the magnetic core 25. The generated flux includes a continuous component and an alternating component, and the amplitude of the generated flux is proportional to the amplitude of the current flowing in each winding 22, 24. Since the amount of current is balanced between the branches, the amplitude of the flux generated in the magnetic core from each winding 22, 24 has the same magnitude. However, since the current flows through each winding in opposite directions around the magnetic core 25 (see, e.g., Figure 9 ), so the polarity of the flux generated by the first winding 22 is opposite to the polarity of the flux generated by the second winding 24. Therefore, the continuous component of the flux generated in the magnetic core 25 by the first winding 22 cancels the continuous component of the flux generated in the magnetic core 25 by the second winding 24.

[0045] In addition, the controller 50 can generate control signals 65, 67 to each power conversion section in a manner that cancels at least a portion of the alternating components of the flux. The disclosed power converter 10 utilizes a single current sensor 40 and a single controller 50 to generate each of the control signals 65, 67. Due to the even division between the branches, when the current sensor is measuring the total input current, the current amplitude detected by the current sensor 40 can be divided by the number of branches to obtain the current amplitude in one branch, or when the current sensor is measuring the branch current, the amplitude of the current detected by the sensor can be multiplied by the number of branches to obtain the amplitude of the total input current. Regardless of the location of the current sensor 40, the controller 50 receives the current feedback signal and generates the control signals 65, 67 to control the operation of the two power conversion sections 12.

[0046] The controller generates control signals 65, 67 at periodic intervals (e.g., in switching cycles) and transmits the control signals 65, 67 to each of the power conversion sections. Since a single controller is used to control each pair of power conversion sections, the controller 50 can shift the time at which the control signals 65, 67 are sent to each power conversion section within a switching cycle. For example, if the power converter 10 includes two power conversion sections, the controller 50 can transmit control signals 65, 67 for one power converter at the beginning of the switching cycle and can transmit control signals 65, 67 for the other power converter at the midpoint of the switching cycle. Similarly, if the power converter 10 includes four power conversion sections, the controller 50 can transmit a control signal for one of the power conversion sections at the beginning of the switching cycle and transmit a control signal for each of the other spaced-apart power conversion sections at a time equal to one-quarter of the switching cycle.

[0047] Shifting the time at which each control signal or group of control signals is sent to the power conversion section can reduce the amplitude of the alternating component of the flux induced in the magnetic core 25 of the magnetic device 20. Controlling the switching elements within each power conversion section to alternately turn on and off generates transient voltages and currents, which produce ripple currents at the input terminals of the power conversion sections. If two power conversion sections are commanded to switch simultaneously, the ripple currents generated at the input terminals will add together due to the cumulative effect of the two power conversion sections switching in series. However, shifting the switching time of one power converter to the middle of the switching cycle shifts the time at which the switching elements within each power conversion section are activated, and thus the time at which the transient voltages and currents are generated. Consequently, the phase of the ripple current between the power conversion sections is shifted. When two power conversion sections are used, the phase of the ripple current can be shifted by 180 degrees, allowing the alternating component of the flux generated by the ripple current to be similarly shifted by 180 degrees. This, in turn, causes the alternating components of the flux to cancel each other rather than have a compounding effect.

[0048] When assembling mutual choke 20, windings 22 and 24 are arranged on magnetic core 25 so that there is a poor mutual coupling coefficient between the windings. Magnetic core 25 includes an air gap 30 to reduce coupling and prevent saturation of core 25 due to DC components. In one embodiment of the present invention, the coupling coefficient between the two windings is between approximately 0.9 and 1.0. Preferably, the coupling coefficient between the two windings is approximately 0.95. Poor mutual coupling reduces the risk of core saturation, which further helps reduce the size of magnetic core 25.

[0049] The disclosed architecture of the power converter 10 allows for a reduction in the size of the power converter. The configuration of the mutual choke 20 and the control of the power conversion section reduce the mutual inductance, causing the DC magnetic component to cancel and spreading the current ripple during the switching cycle, thereby reducing the required current rating of the inductor. The reduced current rating allows the physical configuration (e.g., conductor size and core size) to be smaller and results in the size of the core 25 being physically reduced relative to conventional magnetic component designs. In addition, the use of a single current sensor 40 and a single controller 50 reduces the component count and complexity of the power converter 10.

[0050] For further explanation, an exemplary embodiment of the present invention will be discussed. This example is not intended to be limiting, but rather to illustrate the benefits of the present invention. The exemplary power converter is configured to convert a 150 VDC input voltage to a 500 VDC output. The maximum input of the power converter is 500 amps, and the maximum desired current ripple is 100 amps. The power conversion section operates at a 20 kHz switching frequency, and the target inductance of the input inductor is 50 microhenries.

[0051] As described above, conventional power converters require either a single power conversion section and a single inductor at the input of the power converter, or parallel power conversion sections with separate inductors for each power conversion section. In the first case, a single power conversion section with a single inductor and a 500 ampere rating would require an inductor weighing approximately 69 kilograms. In the second case, a pair of power converters, each with a 250 ampere rating and each with a separate inductor, would each require two inductors weighing approximately 19 kilograms. The combined weight of the inductors for the second case is approximately 38 kilograms.

[0052] In contrast, Figure 1 As shown, the present invention utilizing a single mutual choke 20 requires a choke weighing approximately 6 kg, with each winding on the choke being rated for 250 amps. Figure 4 Another embodiment shown in produces a choke weighing approximately 8 kg, wherein each winding on the choke is rated for 125 amps. It should also be noted that each power conversion section can be rated by dividing the total rating by the number of branches in the power converter 10. Thus, Figure 1 The power conversion section 12 will be rated for 250 amps, and Figure 4 The power conversion section will be rated for 125 amps, consistent with the rating of the corresponding winding in the choke 20. As can be observed, the present invention results in a reduction of approximately fifty to ninety percent in the weight required in the choke compared to conventional chokes, resulting in a corresponding reduction in the size of the choke.

[0053] Furthermore, conventional power converters require a separate controller for each power conversion section. In the example given above, achieving at least some reduction in magnetic components using a parallel converter with conventional power converters results in the use of two separate controllers and a separate current sensor for each controller to regulate the current in each branch. Each controller requires space in the control cabinet, and coordinating the two controllers increases the complexity of the power converter. Furthermore, the additional controller and additional current sensor increase the cost of the power converter.

[0054] In contrast, the present invention utilizes a single current sensor 40 and a single controller 50 to generate control signals for each of the power conversion sections. Thus, the use of parallel power conversion sections can be achieved with a single sensor 40 and a single controller 50, allowing for smaller magnetic components.

[0055] It should be understood that the application of the present invention is not limited to the details of construction and arrangement of components set forth herein. The present invention is capable of other embodiments and can be practiced or implemented in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It should also be understood that the present invention disclosed and defined herein extends to all alternative combinations of two or more individual features mentioned or apparent from the text and / or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein illustrate the best mode for practicing the present invention and will enable others skilled in the art to utilize the present invention.

Claims

1. A power converter, comprising: a plurality of power conversion sections, wherein each power conversion section comprises: an input terminal for receiving a first AC voltage having a first amplitude and a first frequency; and an output terminal for delivering a second DC voltage having a second amplitude and a second frequency; A first mutual choke, the first mutual choke comprising: Magnetic core; a first winding on the magnetic core, the first winding being connected in series between a power source and a first power conversion section selected from the plurality of power conversion sections, the first winding being configured to conduct a first current; and a second winding on the magnetic core, the second winding being connected in series between the power source and a second power conversion section selected from the plurality of power conversion sections, the second winding being configured to conduct a second current, wherein the first winding and the second winding are connected between the power source and the first power conversion section and between the power source and the second power conversion section, respectively, such that the first current flows in a direction opposite to the second current relative to the magnetic core; A second mutual choke, the second mutual choke comprising: a second magnetic core; a third winding on the second magnetic core, the third winding being connected in series between the power source and a third power conversion section selected from the plurality of power conversion sections, the third winding being configured to conduct a third current; and a fourth winding on the second magnetic core, the fourth winding being connected in series between the power source and a fourth power conversion section selected from the plurality of power conversion sections, the fourth winding being configured to conduct a fourth current, wherein the third winding and the fourth winding are connected between the power source and the third power conversion section and between the power source and the fourth power conversion section, respectively, such that the third current flows in a direction opposite to the fourth current relative to the second magnetic core; a current sensor for generating a signal corresponding to the amplitude of the current entering the power conversion section; and a controller for receiving the signal from the current sensor and generating a first set of control signals for the first power conversion section, a second set of control signals for the second power conversion section, a third set of control signals for the third power conversion section, and a fourth set of control signals for the fourth power conversion section in response to the signal from the current sensor, The power converter further comprises: A third mutual choke has a pair of windings connected in a differential mode, wherein the pair of windings is for connection between the power source and each of the first and second mutual chokes.

2. The power converter of claim 1 , wherein: The controller repeatedly generates the first control signal set and the second control signal set at periodic intervals, and The second set of control signals is delivered to the second power conversion section at a second time that differs from a first time when the first set of control signals is delivered to the first power conversion section by one quarter of the periodic interval.

3. The power converter of claim 1 , wherein: The first winding and the first power conversion section at least partially define a first branch, The second winding and the second power conversion section at least partially define a second branch, A common electrical conductor is connected between the power source and each of the first branch and the second branch, and The current sensor is connected to the common electrical conductor such that the signal from the current sensor corresponds to the amplitude of the current conducted in the common electrical conductor.

4. The power converter of claim 1 , wherein: The first winding and the first power conversion section at least partially define a first branch, The second winding and the second power conversion section at least partially define a second branch, and The current sensor is configured to connect one of the first branch and the second branch such that the signal from the current sensor corresponds to an amplitude of a current conducted in one of the first winding and the second winding.

5. The power converter according to claim 1, wherein: The third mutual choke coil comprises: a third magnetic core; a fifth winding on the third magnetic core, the fifth winding being connected in series between the power supply and the first mutual choke, and configured to conduct a fifth current; and The sixth winding on the third magnetic core is connected in series between the power supply and the second mutual choke, and the sixth winding is used to conduct a sixth current, wherein the fifth winding and the sixth winding are respectively connected between the power supply and the first mutual choke and the power supply and the second mutual choke, so that the fifth current flows in the opposite direction to the sixth current relative to the third magnetic core.

6. A modular power converter, comprising: at least one pair of power conversion sections, wherein each pair of power conversion sections is configured to receive a first AC voltage having a first amplitude and a first frequency, and the output is configured to deliver a second DC voltage having a second amplitude and a second frequency; at least one choke, wherein each choke comprises at least one pair of windings connected in a differential mode, and wherein each pair of windings is configured to be connected between a power source for providing the first AC voltage and a pair of power conversion sections in the power conversion section; a current sensor for generating a signal corresponding to an amplitude of a current provided to the modular power converter; as well as a controller for receiving the signal from the current sensor and generating a set of control signals for each pair of power conversion sections in response to the signal from the current sensor, wherein: The modular power converter includes two pairs of power conversion sections and two chokes, and The modular power converter further includes an additional choke having a pair of windings connected in a differential mode, wherein the pair of windings is for connection between the power source and each of the two chokes.

7. The modular power converter of claim 6, wherein the current sensor is operatively connected to generate a signal corresponding to the amplitude of the current conducted in one of the pair of windings in one of the at least one choke.

8. The modular power converter of claim 6, wherein the current sensor is operatively connected to generate a signal corresponding to the amplitude of the current supplied from the power source to the modular power converter.

9. The modular power converter of claim 6, wherein: The controller repeatedly generates each control signal set at periodic intervals, and The set of control signals for one of the power conversion sections in each pair of power conversion sections is delivered to the corresponding power converter at a time that is one quarter of the periodic interval different from the time at which the set of control signals for the other power conversion section in the pair of power conversion sections is delivered.

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