Converter design for novel motor

Abstract

There is provided a power electronic device for driving a switched reluctance motor, comprising: a plurality of phase legs, each phase leg comprising a phase winding, in which the plurality of phase legs are connected in series to form a ring; and a main inverter having a plurality of inverter legs, in which the number of the plurality of legs is equal to the number of the plurality of phase legs, in which each leg of the plurality of legs is connected to two of the plurality of phase legs at a switch node and each of the plurality of phase legs is connected to two of the plurality of legs, and in which each of the plurality of phase legs is connected to two of the plurality of legs, and in which the number of the plurality of legs is equal to the number of the plurality of phase legs. At least one of the phase legs includes at least one voltage source connected in series with a respective phase winding.

Description

Technical Field

[0001] This disclosure relates to power converters and control methods for said power converters. Specifically, this disclosure relates to a power converter for a switched reluctance motor (SRM), which is used as a motor or generator. Background Technology

[0002] Switched reluctance motors (SRMs) can be driven using asymmetric bridge power converters. An asymmetric bridge power converter uses two active switches and two diodes per phase. Each asymmetric bridge provides unidirectional current excitation to one phase of the SRM by applying three possible voltage states. Asymmetric bridges have the advantage of requiring a small number of semiconductor devices to function; however, commercial power modules are typically only available in multiples of a fully filled half-bridge configuration, where each device location includes an active switch and an anti-parallel diode.

[0003] Power electronic converters typically used to drive three-phase motors employ six switches and six diodes to deliver three balancing currents, which are typically sinusoidal with a 120° offset between phases. Such power electronic converters support a maximum total load VA of [value missing]. For an arrangement using a fully filled half-bridge device to implement an asymmetric bridge power converter using commercially available modules, the total supported maximum load VA is also [value missing]. However, this means that the increased number of power semiconductors used is worse compared to conventional three-phase inverters, and therefore, the total installed VA rating of an asymmetric bridge power converter implemented with a fully filled half-bridge will be twice that of a conventional three-phase inverter.

[0004] Against this backdrop, this publicly available teaching content was designed. Summary of the Invention

[0005] A power electronic device for driving a switched reluctance motor is provided, comprising: a plurality of phase arms, each phase arm including a phase winding, wherein the plurality of phase arms are connected in series to form a loop; and a main inverter having a plurality of inverter bridge arms, wherein the number of the plurality of bridge arms is equal to the number of the plurality of phase arms, wherein each of the plurality of bridge arms is connected to two of the plurality of phase arms at a switching node, and each of the plurality of phase arms is connected to two of the plurality of bridge arms, and wherein at least one of the phase arms includes at least one voltage source connected in series with a corresponding phase winding.

[0006] A method for controlling a power electronic device as described in the embodiments and examples herein is further provided, comprising: controlling at least one voltage source to provide cyclic bias current in a plurality of phase arms; and controlling the plurality of inverter bridge arms to provide a plurality of currents at respective switching nodes.

[0007] A switched reluctance motor is also provided, comprising: a stator; a rotor; a housing; and power electronic devices as described in the embodiments and examples herein. Attached Figure Description

[0008] Further details, aspects, and embodiments of the invention will be described by way of example only with reference to the accompanying drawings. In the drawings, the same reference numerals are used to identify the same or similarly functional elements. Elements in the drawings are shown for simplicity and clarity and are not necessarily drawn to scale.

[0009] Figure 1 Asymmetric bridge power converters for driving SRMs are shown according to different embodiments and implementations of the present disclosure; Figure 2 Examples of asymmetric bridges implemented using commercially available power modules according to various embodiments and implementations of this disclosure are shown, wherein each phase requires two fully filled half-bridge arms; Figure 3 Examples of power electronic converters typically used for driving three-phase motors are shown in various embodiments and implementations according to this disclosure; Figure 4 Alternative arrangements according to various embodiments and implementations of the present disclosure are shown, which include asymmetric bridge arms at each end of the series string of phase windings; Figure 5 The arrangement of using a controllable voltage source connected in series with a phase winding to form a loop is shown in various embodiments and implementations of this disclosure; Figure 6 Examples of power converters for driving a three-phase SRM according to various embodiments and implementations of the present disclosure are shown, including a main inverter and an auxiliary converter implementing two voltage sources; Figure 7 Examples of power converters for driving a three-phase SRM according to various embodiments and implementations of the present disclosure are shown. The power converter includes a main inverter implemented by a combination of IGBTs and anti-parallel diodes and an auxiliary converter implemented using MOSFETs. Figure 8 Examples of power converters for driving a three-phase SRM according to various embodiments and implementations of the present disclosure are shown. The power converter includes a main inverter implemented by a combination of IGBTs and anti-parallel diodes and an auxiliary converter implemented using an asymmetric configuration. Figure 9 The diagram illustrates the general arrangement of a power converter for driving a three-phase SRM having two series voltage sources according to various embodiments and implementations of the present disclosure; Figure 10 Alternative embodiments of a power converter for driving a three-phase SRM are shown, according to various embodiments and implementations of the present disclosure, including a main inverter and an auxiliary converter implementing a single voltage source; Figure 11 Alternative embodiments of a power converter for driving a three-phase SRM are shown according to various embodiments and implementations of the present disclosure, the power converter including a main inverter and an auxiliary converter that implement a single voltage source using an asymmetric configuration; Figure 12 The diagram illustrates the general arrangement of a power converter for driving a three-phase SRM having a single series voltage source, according to different embodiments and implementations of this disclosure. Figure 13 An embodiment of the general arrangement for driving a power converter for a three-phase SRM according to different embodiments and implementations of the present disclosure is shown, the three-phase SRM including a main inverter and a voltage source connected in series with each of the phase windings. Figure 14 Various embodiments and implementations of this disclosure are shown for implementation. Figure 13 An embodiment of the overall arrangement of the power converter shown includes a main inverter, a first auxiliary converter that implements two voltage sources, and a second auxiliary converter that implements a single voltage source. Figure 15 An embodiment of the general arrangement for driving a power converter for a three-phase SRM according to various embodiments and implementations of the present disclosure is shown, the three-phase SRM including a main inverter and two voltages connected in series with each phase winding; Figure 16 Various embodiments and implementations of this disclosure are shown for implementation. Figure 15 An embodiment of the overall arrangement of the power converter shown in the figure includes a main inverter and three auxiliary converters, each of the three auxiliary converters implementing two voltage sources; Figure 17 An embodiment of the general arrangement for driving a power converter for a four-phase SRM according to different embodiments and implementations of the present disclosure is shown. The four-phase SRM includes a main inverter and two voltages connected in series with each of the phase windings. Detailed Implementation

[0010] In the following description, for purposes of explanation, numerous specific details of certain embodiments are set forth. References to "embodiments" or similar language in the specification mean that a particular feature, structure, or characteristic described in connection with an embodiment is included at least in that embodiment, but not necessarily in other embodiments.

[0011] Figure 1 An asymmetric bridge power converter for driving an SRM is shown. Figure 1 The asymmetric bridge is arranged to drive a three-phase SRM. The first phase includes a first-phase winding 1 electrically coupled to a first bridge arm A and a second bridge arm B. First bridge arm A includes a first active switch Q1 and a first diode D1, while second bridge arm B includes a second active switch Q2 and a second diode D2. The second phase includes a second-phase winding 2 electrically coupled to a first bridge arm C and a second bridge arm D. First bridge arm C includes a first active switch Q3 and a first diode D3, while second bridge arm D includes a second active switch Q4 and a second diode D4. The third phase includes a third-phase winding 3 electrically coupled to a first bridge arm E and a second bridge arm F. First bridge arm E includes a first active switch Q5 and a first diode D5, while second bridge arm F includes a second active switch Q6 and a second diode D6.

[0012] Figure 1 The active switches Q1 through Q6 are shown as insulated-gate bipolar transistors (IGBTs), but those skilled in the art will recognize that alternative, functionally equivalent semiconductor devices can be used instead of IGBTs or diodes. For example, any type of power field-effect transistor (FET), bipolar junction transistor (BJT), or gate-off (GTO) thyristor can be used. The semiconductor devices used can be made from a variety of semiconductor materials.

[0013] The description will refer to the first phase. Figure 1 The circuit operation. In magnetization mode, when the first phase winding 1 needs to establish a magnetic field, active switches Q1 and Q2 are turned on. Current. The current flows through switch Q1, from arm A through phase winding 1 to arm B, and also through switch Q2. The voltage across phase winding 1... Will equal to In freewheeling mode, only one of Q1 and Q2 is switched on. For example, if Q1 is on and Q2 is off, the current... The current flows through switch Q1, from arm A through phase winding 1 to arm B, and also through diode D2. The voltage across phase winding 1... The current will drop to zero. In demagnetization mode, when the first phase winding 1 no longer needs to establish a magnetic field, both Q1 and Q2 are disconnected. The current flows through diode D1, from arm A through phase winding 1 to arm B, and also through diode D2. The voltage across phase winding 1... Will equal to .

[0014] Each asymmetric bridge applies three possible voltage states: ,0, This provides excitation for one phase of the electrical circuit with a unidirectional current. The advantage of an asymmetric bridge is that it requires fewer semiconductor devices to operate. Using an asymmetric bridge power converter, each phase can be controlled independently. However, commercially available power modules are typically only available in multiples of a fully filled half-bridge configuration, where each device location includes an active switch and an anti-parallel diode.

[0015] Figure 2 An embodiment of an asymmetric bridge implemented using commercially available power modules is shown, wherein each phase requires two fully filled half-bridge arms. The first phase includes a first phase winding 1 electrically coupled to a first bridge arm A and a second bridge arm B. Bridge arm A includes a first active switch Q1 and a second active switch Q2, as well as a first diode D1 and a second diode D2. Bridge arm B includes a third active switch Q3 and a fourth active switch Q4, as well as a third diode D3 and a fourth diode D4. The second phase includes four active switches Q5 through Q8 and four diodes D5 through D8. The third phase includes four active switches Q9 through Q12 and four diodes D9 through D12.

[0016] Figure 3 An embodiment of a power electronic converter typically used to drive a three-phase motor is shown. A total of six switches Q1 to Q6 and six diodes D1 to D6 are used to transfer three balanced currents, typically sinusoidal with a 120° offset, between the phases. If the phase voltages are also sinusoidal, the maximum peak volume on each phase is... ,in, This is the DC-link voltage. The peak arm current, given by the difference between phase currents, is the peak current of a single phase phase. Therefore, for a given DC bus voltage... and the rated current of the switch The total load VA supported by the three-phase inverter is equal to .

[0017] for Figure 2 The arrangement (and its relationship with) Figure 3 Compared to the arrangement which uses twice the number of power semiconductors, the maximum available peak voltage across each phase is equal to the DC bus voltage, and the maximum peak phase current is equal to the switching current, and therefore... Figure 2The total load VA supported by the arrangement is also equal to Therefore, with Figure 3 Compared to the arrangement of power semiconductors, power semiconductors in Figure 2 It was poorly used in the layout.

[0018] Although the current and voltage waveforms applied to the SRM are typically not sinusoidal, it can be expected that... Figure 2 The total installed VA rating of the power semiconductors in the arrangement is much higher than Figure 3 The layout was designed to accommodate this, and therefore a commercially available power switch module was used. Figure 2 The layout may not be cost-effective.

[0019] Figure 4 An alternative arrangement of asymmetrical bridge arms at each end of a series string comprising phase windings is shown. Multiple phase windings 1, 2, and 3 are connected in series, each with a fully filled bridge arm at an intermediate node. Specifically, bridge arm B is connected at the common node of phase windings 1 and 2, and bridge arm C is connected at the common node of phase windings 2 and 3. At the ends of the string, asymmetrical bridge arms A and D are connected to phase windings 1 and 3, respectively. Asymmetrical bridge arms A and D at the ends of the series string carry the full-phase current (i.e., the DC component plus the AC component), while bridge arms B and C at the intermediate nodes carry only the AC component of the current. If each position (i.e., position 1) is implemented using a fully filled half-bridge arm (i.e., for...),... Figure 4 (the four half-bridge arms of the embodiment), then Figure 4 The layout compared to Figure 2 The layout offers a more cost-effective alternative, but still does not Figure 3 The layout may result in potential cost savings.

[0020] Figure 5 This illustrates an arrangement using a controllable voltage source connected in series with the phase winding to form the phase loop PR. Controllable voltage source The voltage source consists of a first-phase winding 1, a second-phase winding 2, and a third-phase winding 3 connected in series. Transport current Through a series of phase windings 1, 2, and 3. For the current... The DC component is controlled to provide a substantially constant circulating current. The AC component... , ,and A three-phase inverter controlled by six switches Q1 to Q6. Current The DC component circulates around the phase loop PR, but does not flow through the switches Q1 to Q6 of the bridge device, thereby reducing the rated current required for switches Q1 to Q6 and / or reducing losses in the switches.

[0021] The sum of the voltages around ring PR must be zero. Therefore:

[0022] if Defined as a rigid DC voltage source, then the sum of the voltages... It must also be a fixed voltage, so that the current... , and Remove one degree of freedom from the current. Consider only the voltage. The AC components, the sum of which must be zero, are the same as in a conventional three-phase bridge with a delta-connected load. If the three voltages and currents form a balanced, but not necessarily sinusoidal, three-phase set, the resulting AC voltage cannot contain any third harmonic of the fundamental frequency, thus limiting the range of possible applied voltage waveforms.

[0023] Only when The full flexibility of the arrangement in Figure 5 can only be guaranteed when it also has a controlled AC component with a voltage bandwidth equivalent to that of the bridge arm. It is expected that the amplitude of the AC component, consisting only of third harmonics, will be smaller than the amplitude of the bridge arm. Furthermore, Must equal And therefore voltage source It must be able to absorb phase current. The exchange component. Therefore, in order to Figure 5 The arrangement allows for fully flexible control of the three-phase current. , and The voltage source will need to be a broadband voltage source. It needs to be a broadband voltage source with AC capability equal to the bridge arm and DC capability equal to the average phase current required by the switched reluctance motor. Voltage source It will also need to be electrically isolated from the DC bus, thus increasing the complexity of the layout compared to powering a voltage source.

[0024] Figure 5 The arrangement utilizes a series voltage source added to a three-phase inverter with three bridge arms. By increasing the series voltage source This allows DC or slowly varying current to be superimposed on the AC current waveform delivered by the three-phase inverter. Therefore, Figure 5 The layout makes better use of commercially available "off-the-shelf" inverter hardware. If the voltage source... It is believed that it can synthesize arbitrary voltage waveforms with a wide bandwidth, so the resulting converter arrangement has four independently controllable voltage nodes, and therefore three independent currents can be controlled. Therefore, Figure 5 The arrangement is equivalent to the operation. Figure 4It has an asymmetrical series arrangement, but has the additional benefit of phase-to-phase current elimination in all three arms.

[0025] pass Figure 4 In this arrangement, the number of bridge legs can be reduced to one more than the number of phases. For example, a three-phase SRM can be implemented using four bridge legs. However, in this arrangement, the outermost bridge leg in the series string of phase windings does not benefit from interphase current cancellation, and therefore the losses in this series arrangement are greater than in an unbroken ring arrangement, such as... Figure 5 As shown in the image.

[0026] Figure 5 Series voltage source arrangement An external power supply is required. In high-power applications where the only readily available power source is the power supply associated with the main inverter, which is typically a high-voltage AC or DC source, providing an external power supply is inconvenient. For example, the DC bus of a typical electric vehicle will be in the range of 200V to 1000V, while the voltage source required to deliver DC current is typically less than 10% of that voltage. When isolation requirements are also considered, power electronic solutions will typically involve isolated DC-DC converters with a power rating of 10% to 20% of the motor's rated power (depending on peak DC losses, which can be as high as 20kW on a 100kW peak-rated traction motor). In typical three-phase applications, the additional cost of a series voltage source with current isolation can easily outweigh the cost of an asymmetrical series arrangement utilizing additional bridge arms.

[0027] Compared to conventional asymmetric bridge arrangements implemented using fully filled commercial half-bridge modules, ring or series topologies offer a more cost-effective converter solution for driving SRMs. However, Figure 4 and Figure 5 The ring and series arrangements have the disadvantages discussed above.

[0028] In this context, it has been designed Figures 6 to 17 The embodiments described herein. In particular, this document provides a power electronic device comprising a main inverter and one or more voltage sources, said one or more voltage sources being implemented by one or more auxiliary converters. The one or more voltage sources are connected in series with these phases to form a loop. Arrangements utilizing more than one voltage source in a phase arm are also described herein. Thus, the total number of voltage sources in series can be between one voltage source and twice the number of voltage sources, because bridge arms exist in the main inverter.

[0029] The auxiliary converter is operable to drive a circulating bias current through the SRM phase windings, wherein the bias current is combined with the current supplied by the main inverter to regulate the net current supplied to each phase winding. Under steady-state excitation, this bias current includes a DC component as well as selected harmonics of the SRM excitation current. In the more general case where excitation is altered due to variations in the desired SRM phase winding current, the average bias current will follow the average value of the desired SRM phase winding current.

[0030] The advantage of the various embodiments presented herein is that the power to drive the circulating bias current in one or more series-connected voltage sources is directly derived from the AC component of the phase current synthesized by the main inverter. These synthesized currents can be the SRM excitation current itself, or they can be currents injected into phase windings having a spectrum different from that of the SRM excitation current. The same auxiliary converter used to provide the power to drive the circulating bias current is used to synthesize the one or more series-connected voltage sources supporting the circulating bias current. Therefore, no additional power supply is required, and thus, no current ground isolation between the voltage sources and the main inverter is required.

[0031] Additionally, the series voltage source can be integrated into or onto the SRM without requiring separate or additional power connections. The series voltage source can be packaged with the main inverter. Alternatively, the series voltage source can be packaged separately from the main inverter and / or the SRM.

[0032] The power electronic device described herein can be used to drive a switched reluctance motor (SRM). The power electronic device may include multiple phase arms. As used herein, the term "phase arm" describes a phase winding, optionally connected in series with one or more voltage sources, wherein a phase arm is connected between two bridge arms. The multiple phase arms may be connected in series to form a loop, wherein current flow is enabled around these phase arms.

[0033] The power electronic device may further include a main inverter. The main inverter may include multiple inverter arms. The number of inverter arms may be equal to the number of phase arms. For example, for a power electronic device configured to drive a two-phase SRM, the main inverter may have two arms. For a power electronic device configured to drive a three-phase SRM, the main inverter may have three arms. Each arm may be connected to two of the multiple phase arms at a switching node, such that each phase arm is connected to two of the multiple phase arms. That is, each phase arm is connected to exactly two phase arms, and each phase arm is connected to exactly two phase arms.

[0034] At least one phase arm may include at least one voltage source connected in series with the corresponding phase winding. In some embodiments, a phase arm may include a single voltage source connected in series with the corresponding phase winding. In some embodiments, a phase arm may include two voltage sources connected in series with the corresponding phase winding. In some embodiments, only one phase arm may include one or two voltage sources connected in series with the corresponding phase winding. In some embodiments, multiple phase arms may include one or two voltage sources connected in series with the corresponding phase winding.

[0035] In some embodiments, at least one voltage source connected in series with a respective phase winding is operable to provide a voltage supporting the circulating bias current in the plurality of phase arms. The circulating bias current may be a bias current having a DC component. In some embodiments, the circulating bias current may include harmonics of the SRM excitation current. The circulating bias current may be combined with the current provided by the main inverter to regulate the net current provided to each phase winding. In some embodiments, the circulating bias voltage may be controlled independently of the current provided by the main inverter.

[0036] In some embodiments, at least one voltage source is operable to provide a voltage having a component at the fundamental electrical frequency of the SRM. In some embodiments, at least one voltage source is operable to provide a voltage having a component at one or more harmonics at the fundamental electrical frequency of the SRM. In some embodiments, at least one voltage source is operable to provide a voltage having a component with a frequency different from the fundamental electrical frequency of the SRM. In some embodiments, at least one voltage source may be used to provide a voltage having a component with a harmonic frequency different from the fundamental electrical frequency of the SRM.

[0037] In some embodiments, at least one voltage source can be implemented using an auxiliary converter. In some embodiments, two voltage sources connected in series to a common bridge arm can be implemented using an auxiliary converter having three half-bridge legs, the three half-bridge legs having a common DC bus. In some embodiments, a single voltage source can be implemented using an auxiliary converter having two half-bridge legs, the two half-bridge legs having a common DC bus. In some embodiments, multiple voltage sources can be implemented using multiple auxiliary converters. In some embodiments, each of the multiple auxiliary converters may have a separate local DC bus. In embodiments, the DC bus can be provided using one or more capacitors.

[0038] In some embodiments, the first terminal of the first voltage source and the first terminal of the second voltage source may be electrically coupled to a common switching node of the bridge arm of the main inverter. The second terminal of the first voltage source may be connected to a first phase winding. The second terminal of the second voltage source may be connected to a second phase winding. In some embodiments, the first terminal of the voltage source may be electrically coupled to a switching node of the bridge arm of the main inverter. The second terminal of the voltage source may be connected to the first phase winding.

[0039] In some embodiments, the rated voltage of the multiple switches in the half-bridge arm including the auxiliary converter may be less than the rated voltage of the multiple switches in the main inverter arm. In some embodiments, the rated current of the multiple switches in the main inverter arm is less than the rated current of the multiple switches in the half-bridge arm including the auxiliary converter.

[0040] The power electronic device disclosed herein can be controlled by a method including the following steps: controlling at least one voltage source to provide circulating bias current in a plurality of phase arms, and controlling a plurality of inverter arms to provide a plurality of currents at corresponding switching nodes of the arms. Controlling at least one voltage source may include switching one or more active switching devices of one or more auxiliary converters. In some examples, switching one or more active switching devices of one or more auxiliary converters may include using pulse width modulation (PWM) technology to generate a desired voltage at the voltage source or to provide a desired circulating bias current. Controlling the plurality of inverter arms may include switching one or more active switching devices of the main inverter. In some embodiments, switching one or more active switching devices of the main inverter may include using pulse width modulation (PWM) technology to provide one or more desired currents.

[0041] In examples of controlling the circulating bias current and / or controlling multiple currents supplied by the main inverter, it is operable to regulate the current flowing in one or more phase arms of a plurality of phase arms. In some embodiments, the power used by a voltage source in the at least one voltage source to provide the circulating bias current can be derived from the current flowing in the voltage source. In some embodiments, the power may originate from one or more AC components of the multiple currents supplied by the main inverter. In embodiments, there may be no additional or external power supply connected to an auxiliary converter to generate one or more voltage sources. In some embodiments, the one or more voltage sources may not be electrically isolated from the main inverter.

[0042] The multiple currents supplied by the main inverter may include components at the fundamental electrical frequency of the SRM. The multiple currents supplied by the main inverter may include harmonic components at the fundamental electrical frequency of the SRM. The multiple currents supplied by the main inverter may include components at frequencies different from the harmonic spectrum of the excitation current of the SRM.

[0043] Controlling power electronic devices may include measuring the average phase current of one or more phase arms. In some embodiments, at least one voltage source may be controlled to maintain the measured average phase current at a value equal to a specified circulating bias current. Controlling power electronic devices may include controlling at least one voltage source to maintain the DC bus voltage of an auxiliary converter at a value substantially the same as a specified value or within a threshold value of a specified value.

[0044] The power electronic device arrangement in these different embodiments can be used as part of a switched reluctance motor, which includes a stator, a rotor, and a housing. In some embodiments, one or both of the at least one voltage source and the main inverter can be integrated within the housing. In some embodiments, one or both of the at least one voltage source and the main inverter can be housed separately from the SRM housing. In some embodiments, at least one voltage source and the main inverter can be integrated in a single package.

[0045] Figure 6 An embodiment of a power converter for driving a three-phase SRM is shown, the power converter including a main inverter implementing two voltage sources and an auxiliary converter.

[0046] The main inverter includes arms A, B, and C, which are formed by switches Q1 through Q6. The auxiliary converter includes arms S, T, and U, which are formed by switches Q7 through Q12. This auxiliary converter includes a local DC-link capacitor. The first phase winding 1 is electrically coupled between bridge arms A and B of the main inverter. The second phase winding 2 is electrically coupled between bridge arm A of the main inverter and bridge arm S of the auxiliary converter. The third phase winding 3 is electrically coupled between bridge arm U of the auxiliary converter and bridge arm A of the main inverter. Bridge arm C of the main inverter is electrically coupled to bridge arm T of the auxiliary converter, such that the voltage... .

[0047] The combination of a phase winding and a combined series voltage source can be referred to as a phase arm. The first phase arm may include a first phase winding 1. The first phase arm is connected between arm A and arm B of the main inverter. The second phase arm may include a voltage source... The second phase winding 2 is connected in series. The second phase arm is connected between arm B and arm C of the main inverter. The third phase arm may include a voltage source. The third phase winding 3 is connected in series. The third phase arm is connected between arm C and arm A of the main inverter. Therefore, the voltage in the first, second, and third phase arms... , and :

[0048] Therefore, each inverter phase arm supports a phase winding voltage. , or Furthermore, the second and third phase arms respectively support voltage. and .

[0049] The auxiliary converter is used to synthesize the voltage to support the circulating bias current through the phase windings. This auxiliary converter includes a local DC bus capacitor. Local DC bus capacitor Power is extracted from the alternating current synthesized by the main inverter and converted into power to support the circulating bias current through the phase windings.

[0050] In addition, the auxiliary converter is used to synthesize an AC voltage that interacts with the AC component of the current flowing through the phase windings. The voltage is generated by switching the bridge arms S, T, and U of the auxiliary converter. and .Voltage and Defined as:

[0051] as well as, and Each of the following can take three possible voltage states: ,0, . and The voltage of each will depend on the state of the switch in the adjacent arm. The voltage varies depending on the various switch states. and as follows:

[0052] The time-averaged intermediate voltage can be generated using an auxiliary converter via a technique such as pulse width modulation (PWM) of the switch at an appropriate rate. In some embodiments, PWM can be performed in the range of 1 kHz to 100 kHz.

[0053] Due to voltage and voltage This is primarily related to the development of the average or DC bias component of the circulating current, and their magnitude will be on the order of the sum of the bias current and the phase resistance. Therefore, and DC bus voltage of the main inverter The value of the auxiliary inverter DC bus will be relatively small compared to the previous value. Therefore, it can be chosen to be much smaller. In some embodiments, The value is in The voltage is between 10% and 20%. Therefore, low-voltage switching devices can be used in the auxiliary converter for switches Q7 through Q12. Suitable embodiments of low-voltage switching devices may include silicon MOSFETs, GaN FETs, or the like.

[0054] exist Figure 6 In the operation of this configuration, the current carried by the switches of the main inverter consists only of the differential component of the phase currents. That is to say:

[0055] If we decompose the phase current into a circulating bias current and an AC excitation component, then... It is the average cyclic bias current, and The AC excitation component consists of the fundamental frequency and its harmonics. It can be written as:

[0056] Therefore, the differential current carried by the phase legs of the main inverter does not include the circulating current. On the other hand, the source... and The current carried does include the circulating current and is equal to the total corresponding phase current. and .

[0057] The average phase current of a typical SRM can have a larger amplitude compared to the fundamental frequency component. For example, taking a bias sinusoidal current ranging from a minimum of 100A to a maximum of 700A, the average current is 400A, and the AC amplitude is 300A. Figure 1 or Figure 2 In the example arrangement, each inverter arm must be able to carry a combined current with an RMS value of 453A. However, assuming in Figure 6 The balanced three-phase excitation in the main inverter arrangement means that the RMS current in each main inverter arm will be an RMS current of a separate AC differential current component, with an RMS value of 367A. Therefore, using Figure 6 With this arrangement, the average RMS current carried by any one of the main inverter arms will be lower than, for example... Figure 1 or Figure 2 The arrangement (where the inverter bridge arm must carry the total phase current) in the layout.

[0058] Therefore, for inverters using the same switching devices, it can be expected that... Figure 6 The losses in the main inverter are lower than Figure 1 , Figure 2 or Figure 4 The inverter losses are due to: (i) fewer bridge arms, and (ii) lower losses in some or all of these bridge arms.

[0059] although Figure 6 The diagram shows a MOSFET switching device, but the semiconductor devices used to implement the main inverter and auxiliary converter can be selected in different ways depending on the desired operating parameters of the system. Figure 7 An embodiment of a power converter for driving a three-phase SRM is shown, which includes a main inverter implemented by a combination of IGBTs and anti-parallel diodes and an auxiliary converter implemented using MOSFETs. Figure 7 The arrangement operation and Figure 6 The arrangement and operation are basically the same.

[0060] Figure 8 An embodiment of a power converter for driving a three-phase SRM is shown, comprising a main inverter implemented using a combination of IGBTs and anti-parallel diodes, and an auxiliary converter implemented using an asymmetric configuration. If the individual phase winding currents are unidirectional, some arms of the auxiliary voltage source can be implemented using an asymmetric configuration, where each arm has an active switching device and a diode. Figure 8 In the embodiment shown, the auxiliary converter's bridge arms S and U are implemented in an asymmetric configuration, while the auxiliary converter's bridge arm T is implemented as a fully filled bridge arm.

[0061] If the current and If it is greater than 0, then and Each of the following can take three possible voltage states: ,0, . and The voltage of each will depend on the state of the switch in the adjacent arm. The voltage varies depending on the various switch states. and voltage as follows:

[0062] Figure 8 The overall operation of the layout and Figure 6 and Figure 7 The overall operation of the arrangement is basically the same, however, it only supports unidirectional phase winding current.

[0063] Figure 9 This diagram illustrates the overall arrangement for driving a power converter with two series-connected voltage sources (SRMs). The overall arrangement represents... Figure 6 , Figure 7 and Figure 8 The overall layout shown is as follows. Figure 9 In this embodiment, the first bridge arm A includes a first switching device Q1 and a second switching device Q2. The second bridge arm B includes a first switching device Q3 and a second switching device Q4. The third bridge arm C includes a first switching device Q5 and a second switching device Q6. A first phase winding 1 is electrically coupled between bridge arms A and B. A second phase winding 2 is connected to a voltage source. A series ground coupling is connected between bridge arm B and bridge arm C. The third phase winding 3 is connected to the voltage source. A series ground is connected between bridge arm C and bridge arm A. Voltage source and voltage source Shared public connectivity at bridge arm C.

[0064] for Figure 6 , Figure 7 , Figure 8 and Figure 9 In each of the arrangements, these two series voltage sources and They are electrically isolated from each other and have a common connection point. The resulting auxiliary converter has a common DC bus, which allows any ripple current components that may appear between the two series voltage sources. and The two are partially or completely compensated for. Therefore, with Associated local energy storage and DC bus capacitors The size can be minimized.

[0065] Figure 10 An alternative embodiment of a power converter for driving a three-phase SRM is shown, comprising a main inverter and an auxiliary converter implementing a single voltage source. The main inverter includes bridge arms A, B, and C, formed by switches Q1 to Q6. The auxiliary converter includes bridge arms T and U, formed by switches Q7 to Q10. The auxiliary converter can be used to synthesize a single arbitrary voltage. The voltage varies depending on various switching states. as follows:

[0066] Figure 11 An alternative embodiment of a power converter for driving a three-phase SRM is shown, comprising a main inverter and an auxiliary converter that implement a single voltage source using an asymmetric configuration. The main inverter includes bridge arms A, B, and C, which are formed by switches Q1 to Q6. The auxiliary converter includes bridge arms T and U and can be used to synthesize the voltage source. The implementation for individual phase winding current is unidirectional. Bridge arm T includes diode D7 and active switch Q8. Bridge arm U includes active switch Q9 and diode D10. Assuming current... If the voltage is greater than zero, then it depends on the voltage of various switching states. as follows:

[0067] Figure 12 This diagram illustrates the overall arrangement for a power converter driving a three-phase SRM with a single series voltage source. The overall arrangement represents... Figure 10 and Figure 11 The overall layout shown is as follows. Figure 12 In this embodiment, the first bridge arm A includes a first switching device Q1 and a second switching device Q2. The second bridge arm B includes a first switching device Q3 and a second switching device Q4. The third bridge arm C includes a first switching device Q5 and a second switching device Q6. A first phase winding 1 is electrically coupled between bridge arms A and B. A second phase winding 2 is electrically coupled between bridge arms B and C. The third phase winding 3 is connected to a voltage source. A series ground is connected between bridge arm C and bridge arm A. Voltage source It is coupled between bridge arm C and the third phase winding 3.

[0068] Figure 13 An embodiment of the general arrangement for driving a power converter for a three-phase SRM is shown, the three-phase SRM including a main inverter and a voltage source connected in series with each of the phase windings. Figure 13 In this embodiment, the first bridge arm A includes a first switching device Q1 and a second switching device Q2. The second bridge arm B includes a first switching device Q3 and a second switching device Q4. The third bridge arm C includes a first switching device Q5 and a second switching device Q6. The first phase winding 1 is connected to the voltage source. A series ground coupling is connected between bridge arm A and bridge arm B. The second phase winding 2 is connected to the voltage source. A series ground coupling is connected between bridge arm B and bridge arm C. The third phase winding 3 is connected to the voltage source. A series ground is connected between bridge arm C and bridge arm A. Voltage source and voltage source A common connection is shared at bridge arm C. Voltage source It is coupled between bridge arm A and the first phase winding 1.

[0069] Since each phase has a voltage source, the DC bias voltage can be evenly distributed among these phases, and therefore these individual voltage sources can each have a lower rated voltage compared to implementations using fewer voltage sources. Furthermore, the AC component of the main inverter and the additional voltage and / or current synthesized by the main inverter can be balanced among the phases of the SRM, thus simplifying control and providing a direct way to minimize any additional alternating energy exchange with the DC bus of the main inverter.

[0070] Figure 14Showing the implementation Figure 13 An embodiment of the power converter arrangement shown includes a main inverter, a first auxiliary converter implementing two voltage sources, and a second auxiliary converter implementing a single voltage source. The main inverter includes arms A, B, and C, formed by switches Q1 to Q6. The first auxiliary converter includes arms S, T, and U, formed by switches Q11 to Q16. The first auxiliary converter includes a first local DC bus capacitor. The second auxiliary converter includes bridge arm Q and bridge arm R, which are formed by switches Q7 and Q10. The second auxiliary converter also includes a second local DC bus capacitor. .

[0071] The first phase winding 1 is electrically coupled between bridge arm R of the second auxiliary converter and bridge arm B of the main inverter. The second phase winding 2 is electrically coupled between bridge arm B of the main inverter and bridge arm S of the first auxiliary converter. The third phase winding 3 is electrically coupled between bridge arm U of the first auxiliary converter and bridge arm A of the main inverter. Bridge arm A of the main inverter is electrically coupled to bridge arm Q of the second auxiliary converter, such that the voltage... The main inverter's bridge arm C is electrically coupled to the first auxiliary converter's bridge arm T, causing the voltage... .

[0072] The first phase arm may include a voltage source The first phase winding 1 is connected in series. The first phase arm is connected between arm A and arm B of the main inverter. The second phase arm may include a voltage source. The second phase winding 2 is connected in series. The second phase arm is connected between arm B and arm C of the main inverter. The third phase arm may include a voltage source. The third phase winding 3 is connected in series. The third phase arm is connected between arm C and arm A of the main inverter. Therefore, the voltage in the first, second, and third phase arms... , and :

[0073] Therefore, each inverter phase arm supports one phase winding voltage. , or Furthermore, each phase arm supports a voltage. , and .

[0074] The first auxiliary converter is used to synthesize an AC voltage that interacts with the AC component of the current flowing through the phase winding. Voltage is generated through the switching arms S, T, and U of the first auxiliary converter. and voltage .Voltage and voltage Defined as:

[0075] as well as,

[0076] The second auxiliary converter synthesizes an AC voltage that interacts with the AC component of the current flowing through the phase winding. This voltage is generated by switching arms Q and R of the second auxiliary converter. .Voltage Defined as:

[0077] Each , and Three possible voltage states can be adopted: ,0, Each , and The voltage will depend on the state of the switches in the adjacent bridge arms of the corresponding auxiliary converter.

[0078] Figure 15 An embodiment of the general arrangement for driving a power converter for a three-phase SRM is shown, the three-phase SRM including a main inverter and two voltages connected in series with each of these phase windings. Figure 15 In this embodiment, the first bridge arm A includes a first switching device Q1 and a second switching device Q2. The second bridge arm B includes a first switching device Q3 and a second switching device Q4. The third bridge arm C includes a first switching device Q5 and a second switching device Q6. A voltage source is provided between the first phase winding 1 and bridge arms A and B. and Series electrical coupling. The second phase winding 2 is connected to the voltage source. and A series electrical coupling is connected between bridge arm B and bridge arm C. The third phase winding 3 is connected to the voltage source. and An electrical coupling is connected in series between bridge arm C and bridge arm A. Voltage source and voltage source A common connection is shared at bridge arm A. Voltage source and voltage source A common connection is shared at bridge arm B. Voltage source and voltage source Shared public connectivity at bridge arm C.

[0079] Figure 15 The layout combines Figure 6 and Figure 13 Advantages of this implementation method. Specifically, each phase is supported by two voltage sources, with one voltage source on each side of the corresponding phase winding. Therefore, each bridge arm is associated with a separate auxiliary converter, which can be used in conjunction with... Figure 6 It is implemented in the same way as the other implementation.

[0080] Figure 16 Showing the implementation Figure 15 An embodiment of the power converter arrangement shown includes a main inverter and three auxiliary converters, each of which implements two voltage sources. The main inverter includes bridge arms A, B, and C, which are formed by switches Q1 to Q6.

[0081] The first auxiliary converter includes bridge arms S, T, and U, which are formed from switches Q19 to Q24. The first auxiliary converter includes a first local DC bus capacitor. The second auxiliary converter includes bridge arms P, Q, and R, which are formed by switches Q13 to Q18. The second auxiliary converter also includes a second local DC bus capacitor. The third auxiliary converter includes bridge arms L, M, and N, which are formed by switches Q7 through Q12. The third auxiliary converter also includes a third local DC bus capacitor. .

[0082] The first phase winding 1 is electrically coupled between bridge arm N of the third auxiliary converter and bridge arm P of the second auxiliary converter. The second phase winding 2 is electrically coupled between bridge arm R of the second auxiliary converter and bridge arm S of the first auxiliary converter. The third phase winding 3 is electrically coupled between bridge arm U of the first auxiliary converter and bridge arm L of the third auxiliary converter.

[0083] The main inverter's bridge arm A is electrically coupled to the bridge arm M of the third auxiliary converter, for example, via voltage... The main inverter's bridge arm B is electrically coupled to the second auxiliary converter's bridge arm Q, for example, via a voltage... The main inverter's bridge arm C is electrically coupled to the first auxiliary converter's bridge arm T, for example, via voltage... .

[0084] The first phase arm may include a voltage source and voltage source The first phase winding 1 is connected in series. The first phase arm is connected between arms A and B of the main inverter. The second phase arm may include a voltage source. and voltage source The second phase winding 2 is connected in series. The second phase arm is connected between arms B and C of the main inverter. The third phase arm may include a voltage source. and voltage source The third phase winding 3 is connected in series. The third phase arm is connected between arm C and arm A of the main inverter. Therefore, the voltage in the first, second, and third phase arms... , and :

[0085] The first auxiliary converter is used to synthesize an AC voltage that interacts with the AC component of the current flowing through the phase winding. and Defined as:

[0086] as well as,

[0087] The second auxiliary converter is used to synthesize an AC voltage that interacts with the AC component of the current flowing through the phase winding. and Defined as:

[0088] as well as,

[0089] The third auxiliary converter is used to synthesize an AC voltage that interacts with the AC component of the current flowing through the phase winding. and Defined as:

[0090] as well as,

[0091] Each , , , , and Three possible voltage states are possible: ,0, Each voltage , , , , and This will depend on the state of the switches in the adjacent bridge arms of the corresponding auxiliary converter.

[0092] Figure 17 An embodiment of the general arrangement for driving a power converter for a four-phase SRM is shown, the four-phase SRM including a main inverter and two voltages connected in series with each of these phase windings.

[0093] exist Figure 17 In this embodiment, the first bridge arm A includes a first switching device Q1 and a second switching device Q2. The second bridge arm B includes a first switching device Q3 and a second switching device Q4. The third bridge arm C includes a first switching device Q5 and a second switching device Q6. The fourth bridge arm D includes a first switching device Q7 and a second switching device Q8. A voltage source is provided between the first phase winding 1 and bridge arms A and B. and Series electrical coupling. The second phase winding 2 is connected to the voltage source. and A series electrical coupling is connected between bridge arm B and bridge arm C. The third phase winding 3 is connected to the voltage source. and An electrical coupling is connected in series between bridge arm C and bridge arm D. The fourth phase winding 4 is connected to the voltage source. and An electrical coupling is connected in series between bridge arm D and bridge arm A. Voltage source and voltage source A common connection is shared at bridge arm A. Voltage source and voltage source A common connection is shared at bridge arm B. Voltage source and voltage source A common connection is shared at bridge arm C. Voltage source and voltage source Shared public connectivity at bridge arm D.

[0094] exist Figure 17 In the implementation of the arrangement, the voltage source and This can be implemented by a first auxiliary converter comprising three bridge arms and a first local DC bus capacitor. Voltage source and voltage source This can be achieved using a second auxiliary converter that includes three bridge arms and a second local DC bus capacitor. Voltage source and voltage source This can be achieved using a third auxiliary converter, which includes three bridge arms and a third local DC bus capacitor. Voltage source and voltage source It can be implemented by a fourth auxiliary converter including three bridge arms and a fourth local DC bus capacitor.

[0095] Advantageously, for the arrangement according to this disclosure, the switches of the main inverter can be sized to carry only differential current, rather than full-phase current. Under symmetrical excitation conditions, each main inverter arm experiences the same load. Therefore, since there is no DC current, the two switch positions in each arm will experience the same average load, resulting in an equal distribution of losses across the main inverter switches. Thus, the function of the main inverter switches can be implemented using commercially available power switch modules comprising one or more fully filled half-bridges with the same rated current. This is consistent with... Figure 1 , Figure 2 or Figure 4 The inverter arrangement contrasts with that of the other inverters. Figure 1 , Figure 2 or Figure 4 In inverter arrangements, the presence of a DC component in one or more of these arms will result in an asymmetric distribution of losses across inverter switching positions.

[0096] Compared to the high-voltage components of the main inverter, the lower-voltage components in the auxiliary converter are expected to have lower cost and generate lower losses. Therefore, the total cost of the main inverter and auxiliary converter can be expected to be lower than [the cost is determined by the following formula]. Figure 4 The total cost of the inverter arrangement is determined by the requirement that the number of bridge arms must be greater than the number of phases (e.g., four bridge arms for a three-phase implementation), and at least two of these bridge arms must be rated for all-phase current. Furthermore, the combined efficiency of the main inverter and auxiliary converter can be expected to be higher than [previous value]. Figure 4 The overall efficiency of the layout.

[0097] Those skilled in the art will recognize that there are many possible alternative arrangements that can use different numbers of SRM phases and / or different numbers of voltage sources. These alternative arrangements have the same advantages discussed with respect to the different specific embodiments described herein.

[0098] The embodiments and examples of this disclosure provide a power electronic device for driving a switched reluctance motor, comprising: a plurality of phase arms, each phase arm including a phase winding, wherein the plurality of phase arms are connected in series to form a loop; and a main inverter having a plurality of inverter bridge arms, wherein the number of the plurality of bridge arms is equal to the number of the plurality of phase arms, wherein each of the plurality of bridge arms is connected to two of the plurality of phase arms at a switching node, and each of the plurality of phase arms is connected to two of the plurality of bridge arms, and wherein at least one of the phase arms includes at least one voltage source connected in series with a corresponding phase winding.

[0099] In some embodiments or implementations disclosed herein, the at least one voltage source is operable to provide voltage to support the cyclic bias current in the plurality of phase arms.

[0100] In some embodiments or implementations disclosed herein, the cyclic bias current is controlled independently of the main inverter.

[0101] In some embodiments or implementations disclosed herein, the at least one voltage source is operable to provide a voltage having components at one or more frequencies, wherein the one or more frequencies include one or more of the following: the fundamental electrical frequency of the switched reluctance motor; harmonics of the fundamental electrical frequency of the switched reluctance motor; and frequencies different from the fundamental electrical frequency of the switched reluctance motor or harmonics of the fundamental electrical frequency of the switched reluctance motor.

[0102] In some embodiments or implementations disclosed herein, at least one voltage source is provided by an auxiliary converter.

[0103] In some embodiments or implementations disclosed herein, the at least one voltage source comprises two voltage sources connected in series, and the auxiliary converter comprises three half-bridge arms having a common DC bus.

[0104] In some embodiments or implementations disclosed herein, the two voltage sources include a first voltage source having a first terminal and a second terminal, and a second voltage source having a first terminal and a second terminal, wherein the first terminal of the first voltage source and the first terminal of the second voltage source are electrically coupled to the switching node of the inverter bridge arm of the main inverter, and wherein the second terminal of the first voltage source is electrically coupled to a first phase winding and the second terminal of the second voltage source is electrically coupled to a second phase winding.

[0105] In some embodiments or implementations disclosed herein, the at least one voltage source includes a single voltage source, and the auxiliary converter includes two half-bridge arms having a common direct current (DC) bus.

[0106] In some embodiments or implementations disclosed herein, the single voltage source includes a first terminal and a second terminal, the first terminal being electrically coupled to the switching node of the inverter bridge arm of the main inverter, and the second terminal being electrically coupled to the corresponding phase winding.

[0107] In some embodiments or implementations disclosed herein, the rated voltage of multiple switches in the half-bridge arm including the auxiliary converter is less than the rated voltage of multiple switches in the main inverter arm.

[0108] In some embodiments or implementations disclosed herein, the rated current of multiple switches in multiple main inverter bridge arms is less than the rated current of multiple switches in multiple half-bridge arms including auxiliary converters.

[0109] Further embodiments and examples of this disclosure provide methods for controlling power electronic devices as described in the embodiments and examples herein, including: controlling at least one voltage source to provide cyclic bias current in a plurality of phase arms; and controlling the plurality of inverter bridge arms to provide a plurality of currents at respective switching nodes.

[0110] In some embodiments or implementations disclosed herein, controlling the cyclic bias current and controlling multiple currents provided by the main inverter are operable to regulate the current flowing in each of the multiple phase arms.

[0111] In some embodiments or implementations disclosed herein, the power source used by the voltage source of the at least one voltage source to provide the cyclic bias current originates from the current flowing in the voltage source.

[0112] In some embodiments or implementations disclosed herein, the power for the at least one voltage source is derived from one or more alternating current (AC) components of the plurality of currents provided by the main inverter.

[0113] In some embodiments or implementations disclosed herein, the multiple currents provided by the main inverter include components at the fundamental electrical frequency and harmonics of the switched reluctance motor.

[0114] In some embodiments or implementations disclosed herein, the multiple currents provided by the main inverter include components at frequencies different from the harmonic spectrum of the excitation current of the switched reluctance motor.

[0115] Some embodiments or implementations disclosed herein also include measuring the average phase current; and controlling the at least one voltage source to maintain the measured average phase current at a specified cyclic bias current.

[0116] Some embodiments or implementations disclosed herein also include controlling the at least one voltage source to maintain the DC bus voltage of the auxiliary converter within a specified threshold value.

[0117] Other embodiments and examples of this disclosure provide a switched reluctance motor, including: a stator; a rotor; a housing; and power electronic devices as described in the embodiments and examples herein.

[0118] In some embodiments or implementations disclosed herein, the at least one voltage source is integrated within the housing of the switched reluctance motor.

[0119] In some embodiments or implementations disclosed herein, the at least one voltage source and the main inverter are integrated in a single package.

[0120] In some embodiments or implementations disclosed herein, the at least one voltage source is housed separately from the switched reluctance motor and the main inverter.

[0121] In some embodiments or implementations disclosed herein, the main inverter is integrated within the housing of the switched reluctance motor.

[0122] In some embodiments or implementations disclosed herein, the main inverter is housed separately from the switched reluctance motor.

[0123] All features disclosed in this specification (including any appended claims, abstract, and drawings) can be combined in any combination, except that some features are mutually exclusive. Unless otherwise expressly stated, each feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by an alternative feature for the same, equivalent, or similar purpose. Therefore, unless otherwise expressly stated, each feature disclosed in one embodiment of equivalent or similar features in the general series...

[0124] This teaching is not limited to the details of any of the foregoing embodiments. Any novel combination of the features disclosed in this specification (including any appended claims, abstract, and drawings) is conceivable. The claims should not be construed as covering only the foregoing embodiments, but also any variations falling within the scope of the claims.

Claims

1. A power electronic device for driving a switched reluctance motor, comprising: Multiple phase arms, each phase arm including a phase winding, wherein the multiple phase arms are connected in series to form a loop; and The main inverter has multiple inverter arms, wherein the number of multiple arms is equal to the number of multiple phase arms. Wherein, each of the plurality of bridge arms is connected to two phase arms of the plurality of phase arms at a switching node, and each of the plurality of phase arms is connected to two bridge arms of the plurality of bridge arms, and At least one phase arm includes at least one voltage source connected in series with the corresponding phase winding.

2. The power electronic device according to claim 1, wherein, The at least one voltage source is operable to provide a voltage to support the cyclic bias current in the plurality of phase arms.

3. The power electronic device according to claim 2, wherein, The cyclic bias current is controlled independently of the main inverter.

4. The power electronic device according to claim 1, wherein, The at least one voltage source is operable to provide a voltage having components at one or more frequencies, wherein the one or more frequencies include one or more of the following: The fundamental frequency of the switched reluctance motor; The harmonics of the fundamental electrical frequency of the switched reluctance motor; and A frequency that is different from the fundamental frequency of the switched reluctance motor or the harmonic of the fundamental frequency of the switched reluctance motor.

5. The power electronic device according to claim 1, wherein, The at least one voltage source is provided by an auxiliary converter.

6. The power electronic device according to claim 5, wherein, The at least one voltage source comprises two voltage sources connected in series, and The auxiliary converter includes three half-bridge arms that have a common DC bus.

7. The power electronic device according to claim 6, wherein, The two voltage sources include a first voltage source having a first terminal and a second terminal, and a second voltage source having a first terminal and a second terminal. Wherein, the first terminal of the first voltage source and the first terminal of the second voltage source are electrically coupled to the switching node of the inverter bridge arm of the main inverter, and The second terminal of the first voltage source is electrically coupled to the first phase winding, and the second terminal of the second voltage source is electrically coupled to the second phase winding.

8. The power electronic device according to any one of claims 5 to 7, wherein, The at least one voltage source includes a single voltage source, and The auxiliary converter includes two half-bridge arms that have a common DC bus.

9. The power electronic device according to claim 8, wherein, The single voltage source includes a first terminal and a second terminal, the first terminal being electrically coupled to the switching node of the inverter bridge arm of the main inverter, and the second terminal being electrically coupled to the corresponding phase winding.

10. The power electronic device according to any one of claims 1 to 9, wherein, The rated voltage of multiple switches in the half-bridge arm, including the auxiliary converter, is less than the rated voltage of multiple switches in the main inverter arm.

11. The power electronic device according to any one of claims 1 to 10, wherein, The rated current of multiple switches in the main inverter bridge arm is less than the rated current of multiple switches in the half-bridge arm including the auxiliary converter.

12. A method for controlling a power electronic device according to any one of claims 1 to 11, comprising: Control at least one voltage source to provide cyclic bias current in multiple phase arms; and Control multiple inverter arms to provide multiple currents at the corresponding switching nodes.

13. The method according to claim 12, wherein, The control of the cyclic bias current and the control of the plurality of currents provided by the main inverter are operable to regulate the current flowing in each of the plurality of phase arms.

14. The method according to claim 13, wherein, The power used by one of the at least one voltage source to provide the cyclic bias current originates from a current flowing in the voltage source.

15. The method according to any one of claims 12 to 14, wherein, The power used for the at least one voltage source is derived from one or more alternating current (AC) components of the plurality of currents supplied by the main inverter.

16. The method according to any one of claims 12 to 15, wherein, The multiple currents provided by the main inverter include components at the fundamental electrical frequency of the switched reluctance motor and the harmonics of the fundamental electrical frequency.

17. The method according to any one of claims 12 to 16, wherein, The multiple currents provided by the main inverter include components at frequencies different from the harmonic spectrum of the excitation current of the switched reluctance motor.

18. The method according to any one of claims 12 to 17, further comprising measuring the average phase current; and The at least one voltage source is controlled to maintain the measured average phase current at a specified cyclic bias current.

19. The method according to any one of claims 12 to 18, further comprising: The at least one voltage source is controlled to maintain the DC bus voltage of the auxiliary converter within a specified threshold value.

20. A switched reluctance motor, comprising: stator; Rotor; case; as well as The power electronic device according to any one of claims 1 to 11.

21. The switched reluctance motor according to claim 20, wherein, At least one voltage source is integrated within the housing of the switched reluctance motor.

22. The switched reluctance motor according to claim 20 or 21, wherein, At least one voltage source and main inverter are integrated in a single package.

23. The switched reluctance motor according to claim 20, wherein, At least one voltage source is separately housed from the switched reluctance motor and the main inverter.

24. The switched reluctance motor according to claim 20 or 21, wherein, The main inverter is integrated within the housing of the switched reluctance motor.

25. The switched reluctance motor according to any one of claims 20 to 23, wherein, The main inverter is housed separately from the switched reluctance motor.

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