Dual-frequency power supply system and method suitable for double-fed linear motor

Abstract

This application discloses a dual-frequency power supply system and method for a doubly-fed linear motor. The doubly-fed linear motor includes a stator and a mover. The stator is powered by a dual-frequency power supply, forming two independent first traveling wave magnetic fields and a second traveling wave magnetic field. The current amplitude and phase of the stator's dual-frequency power supply are independently adjustable. The mover is powered by a dual-frequency power supply, with its first power supply frequency synchronized with the first traveling wave magnetic field of the stator and its second power supply frequency synchronized with the second traveling wave magnetic field of the stator. The current amplitude and phase of the mover's dual-frequency power supply are independently adjustable. Under the first traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the first power supply frequency. Under the second traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the second power supply frequency. The mover includes at least two control loops, each of which performs dual-frequency power supply electromechanical energy conversion, increasing the overall electromechanical energy conversion control freedom of the doubly-fed linear motor.

Description

Technical Field

[0001] This application relates to the field of motor and control technology, and in particular to a dual-frequency power supply system and method suitable for doubly fed linear motors. Background Technology

[0002] High-speed maglev train technology addresses the critical national need for high-speed, high-capacity intercity transportation and possesses significant strategic value. For maglev applications at speeds of 600 km / h or higher, the inherent limitations of existing long-stator linear synchronous motor (LLSM) systems, such as track-vehicle phase coupling, dynamic coupling of levitation and traction control, and vehicle power supply technology, pose potential constraints to speed increases. Compared to existing LLSM systems, the "double-fed linear motor (DFLM) quasi-synchronous operation (QSO)" system integrates traction, levitation, and power supply capabilities, and offers advantages in track-vehicle frequency coupling and dynamic decoupling of levitation and traction.

[0003] In doubly-fed linear motor control, slip power is required to provide contactless power to the mover (i.e., the carriage of the maglev train). The slip power of the doubly-fed linear motor... Algebraically coupled with the product of slip frequency and traction force, it can be expressed as:

[0004] in, The slip frequency, For traction force, The value is the pole gap. Here, the negative sign is defined as the energy injected from the follower into the air gap; therefore, in real engineering applications, the slip power is negative.

[0005] Currently known slip power control strategies for doubly-fed linear motors all employ direct control of the slip frequency. However, when the doubly-fed linear motor operates in scenarios with insufficient reaction force or no driving force required, such as the coasting mode of a maglev train (i.e., traveling at a relatively slow speed), it will not generate sufficient air resistance, thus resulting in insufficient driving force. In static levitation or natural deceleration scenarios, no traction force is required. In these cases, according to the slip power equation, it is evident that the doubly-fed linear motor cannot generate sufficient slip power, or even any slip power at all; or a very high slip frequency is required, further leading to very high reactive power and extremely large inverter capacity. Rail transit applications based on doubly-fed linear motors also face the problem of maintaining or controlling slip power in scenarios with insufficient reaction force or no driving force required.

[0006] In summary, current control methods cannot solve the problem of maintaining or controlling slip power in doubly-fed linear motors under under-reaction force conditions. Furthermore, doubly-fed linear motors based on a single-frequency power supply also suffer from insufficient degrees of freedom in controlling traction and normal force fluctuations. Summary of the Invention

[0007] The main objective of this application is to provide a dual-frequency power supply system and method suitable for doubly fed linear motors, aiming to solve the technical problem of insufficient freedom in existing slip power control, while increasing the freedom of electromechanical energy conversion control of doubly fed linear motors.

[0008] To achieve the above objectives, this application proposes a dual-frequency power supply system suitable for a doubly-fed linear motor, the dual-frequency power supply system for a doubly-fed linear motor comprising: The doubly fed linear motor includes a stator and a mover; The stator is powered by dual frequency, forming two independent first traveling wave magnetic fields and second traveling wave magnetic fields on the stator. The current amplitude and phase of the stator powered by dual frequency are independently adjustable. The mover is powered by a dual-frequency power supply. The first power supply frequency of the mover is synchronized with the first traveling wave magnetic field of the stator, and the second power supply frequency of the mover is synchronized with the second traveling wave magnetic field of the stator. The current amplitude and phase of the dual-frequency power supply of the mover are independently adjustable. Under the first traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the first power supply frequency; Under the second traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the second power supply frequency; The mover includes at least two control loops, which respectively perform dual-frequency power supply electromechanical energy conversion, increasing the overall electromechanical energy conversion control freedom of the doubly fed linear motor; The electromechanical energy control and transformation includes, but is not limited to, the adjustment of the traction force, power supply, and normal force of the doubly fed linear motor.

[0009] Optionally, the control loop is used to independently adjust the amplitude and direction of the traction force; The combined control of the control loop is used to meet the adaptability of the doubly fed linear motor to traction conditions. The control circuit included in the doubly fed linear motor mover is used to independently adjust the magnitude and phase of traction force fluctuations, and the overall traction force fluctuations of the doubly fed linear motor are offset by the combination of various control circuits.

[0010] Optionally, the control circuits included in the doubly fed linear motor mover each operate independently in subsynchronous traction mode or supersynchronous braking mode, and control the power supply from the stator side to the mover side through the combination of the various control circuits. When all control circuits of the doubly fed linear motor share a common DC bus, a DC bus capacitor is used to filter the fluctuations in the power supply. When the control circuits of the doubly fed linear motor do not share a DC bus, a separate DC bus capacitor is set on the independent DC bus of each circuit to filter the power fluctuations of each circuit.

[0011] Optionally, the first power supply frequency or the second power supply frequency is used for electromechanical energy conversion, which includes traction force and power supply control; Another power supply frequency is used to weaken the traveling wave magnetic field of the stator at the corresponding frequency, or to regulate the fluctuation of the normal force.

[0012] Optionally, the combination of the various control loops is used to adjust the overall normal force requirement of the doubly fed linear motor; The combination of the various control loops is used to regulate the overall normal force fluctuation of the doubly fed linear motor.

[0013] Optionally, the system is applied to stationary, natural deceleration, slow travel, slow acceleration, and slow deceleration conditions of wheel-rail transportation. In the aforementioned rail transit scenario, the traction force and power supply are adjusted based on the control loop, without considering the adjustment of the normal force.

[0014] Optionally, the system is applied to the static levitation, natural deceleration, slow driving, slow acceleration and slow deceleration conditions of high-speed maglev transportation; In the high-speed maglev transportation scenario, the traction force, power supply, and normal force are adjusted based on the control loop.

[0015] Optionally, under the stationary or static buoyancy and natural deceleration conditions, the current amplitudes corresponding to the first and second stator power supply frequencies are equal, and the stator's dual-frequency power supply frequency... and They are respectively:

[0016]

[0017] in Used for regulating the power supply. The electrical frequency corresponding to the vehicle speed; The mover includes a first mover unit and a second mover unit, and is independently controlled by a first control loop and a second control loop. The first power supply frequency of the first mover unit is subsynchronous traction, and the second power supply frequency is a field weakening frequency. The second power supply frequency of the second mover unit is supersynchronous braking, and the first power supply frequency is a field weakening frequency. Alternatively, a combination configuration can be provided where the first moving subunit is for subsynchronous traction and the second moving subunit is for supersynchronous braking; In the high-speed maglev transportation scenario, the amplitude of the mover current corresponding to the subsynchronous traction and supersynchronous braking modes is the normal force that meets the levitation requirements. The weak magnetic current vector corresponding to the mover is opposite to the corresponding stator current vector, and their ratio is the winding reduction coefficient. In the context of rail transit, the adjustment of normal force is not considered.

[0018] Optionally, under conditions of slow driving, coasting, slow acceleration, or slow deceleration, the current amplitudes corresponding to the first and second stator power supply frequencies are not equal, and the stator's dual-frequency power supply frequency... and They are respectively:

[0019]

[0020] in Used for regulating the power supply. The electrical frequency corresponding to the vehicle speed; The mover includes a first mover unit and a second mover unit, and is independently controlled by a first control loop and a second control loop. The first power supply frequency of the first mover unit is subsynchronous traction, and the second power supply frequency is a field weakening frequency. The second power supply frequency of the second mover unit is supersynchronous braking, and the first power supply frequency is a field weakening frequency. Alternatively, it can be a combination configuration where one moving subunit is for subsynchronous traction and the other moving subunit is for supersynchronous braking; In the high-speed maglev transportation scenario, the amplitude of the mover current corresponding to the subsynchronous traction and supersynchronous braking modes is the normal force that meets the levitation requirements. The weak magnetic current vector corresponding to the mover is opposite to the corresponding stator current vector, and their ratio is the winding reduction coefficient. In the context of rail transit, the adjustment of normal force is not considered.

[0021] Furthermore, to achieve the above objectives, this application also proposes a dual-frequency power supply method suitable for a doubly-fed linear motor, wherein the method is applied to the dual-frequency power supply system for a doubly-fed linear motor described in any of the above claims, and the method includes: The doubly fed linear motor includes a stator and a mover; The stator is powered by dual frequency, forming two independent first traveling wave magnetic fields and second traveling wave magnetic fields on the stator. The current amplitude and phase of the stator powered by dual frequency are independently adjustable. The mover is powered by a dual-frequency power supply. The first power supply frequency of the mover is synchronized with the first traveling wave magnetic field of the stator, and the second power supply frequency of the mover is synchronized with the second traveling wave magnetic field of the stator. The current amplitude and phase of the dual-frequency power supply of the mover are independently adjustable. Under the first traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the first power supply frequency; Under the second traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the second power supply frequency; The mover includes at least two control loops, which respectively perform dual-frequency power supply electromechanical energy conversion, increasing the overall electromechanical energy conversion control freedom of the doubly fed linear motor; The electromechanical energy control and transformation includes, but is not limited to, the adjustment of the traction force, power supply, and normal force of the doubly fed linear motor.

[0022] This application presents a doubly-fed linear motor comprising a stator and a mover. The stator employs dual-frequency power supply, forming two independent first traveling wave magnetic fields and a second traveling wave magnetic field. The current amplitude and phase of the stator's dual-frequency power supply are independently adjustable. The mover also employs dual-frequency power supply, with its first power supply frequency synchronized with the first traveling wave magnetic field of the stator and its second power supply frequency synchronized with the second traveling wave magnetic field of the stator. The current amplitude and phase of the mover's dual-frequency power supply are independently adjustable. Under the first traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the first power supply frequency. Under the second traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the second power supply frequency. The mover contains at least two control loops, each performing dual-frequency power supply electromechanical energy conversion separately. This solves the technical problem of insufficient freedom in existing slip-ring power control and increases the overall electromechanical energy conversion control freedom of the doubly-fed linear motor. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a structural block diagram provided for Embodiment 1 of the dual-frequency power supply system applicable to a doubly-fed linear motor; Figure 2 This is a schematic diagram of the stator dual-frequency power supply provided in Embodiment 1 of the dual-frequency power supply system applicable to a doubly-fed linear motor in this application; Figure 3 This is a schematic diagram of a doubly fed linear motor system with two control loops as provided in Embodiment 1 of the dual-frequency power supply system applicable to doubly fed linear motors in this application; Figure 4This application provides a stator current-oriented dual-frequency power supply system for a doubly-fed linear motor, as described in Embodiment 1. Schematic diagram of dual-frequency excitation in coordinate system; Figure 5 This is a schematic diagram of dual-frequency excitation with the introduction of a field weakening current vector, provided in Embodiment 1 of the dual-frequency power supply system applicable to a doubly fed linear motor in this application. Figure 6 This is a schematic diagram of the current configuration under coasting or slow acceleration conditions provided in Embodiment 1 of the dual-frequency power supply system applicable to a doubly fed linear motor in this application. Figure 7 This is a schematic diagram of a finite element model of a doubly-fed linear motor provided for Embodiment 1 of the dual-frequency power supply system applicable to doubly-fed linear motors in this application; Figure 8 This is a schematic diagram of the current configuration under coasting or slow acceleration conditions provided in Embodiment 1 of the dual-frequency power supply system applicable to a doubly fed linear motor in this application. Figure 9 This is a schematic diagram showing the result of applying a weak field adjustment to the mover side using dual-frequency excitation, as provided in Embodiment 1 of the dual-frequency power supply system applicable to a doubly fed linear motor.

[0026] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0028] Reference Figure 1 , Figure 1 This is a structural block diagram provided for a first embodiment of a dual-frequency power supply system for a doubly-fed linear motor according to this application. The doubly-fed linear motor includes a stator 10 and a mover 20; The stator 10 is powered by dual frequency, forming two independent first traveling wave magnetic fields and second traveling wave magnetic fields on the stator. The current amplitude and phase of the stator dual frequency power supply are independently adjustable. The mover 20 is powered by dual frequency. The first power supply frequency of the mover is synchronized with the first traveling wave magnetic field of the stator, and the second power supply frequency of the mover is synchronized with the second traveling wave magnetic field of the stator. The current amplitude and phase of the dual frequency power supply of the mover are independently adjustable. Under the first traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the first power supply frequency; Under the second traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the second power supply frequency; The mover includes at least two control loops 30, which respectively perform dual-frequency power supply electromechanical energy conversion, increasing the overall electromechanical energy conversion control freedom of the doubly fed linear motor; The electromechanical energy control and transformation includes, but is not limited to, the adjustment of the traction force, power supply, and normal force of the doubly fed linear motor.

[0029] It should be noted that the aforementioned Doubly-Fed Linear Motor (DFLM) is a type of linear motor where both the stator and mover can be connected to AC power and form electromagnetic coupling. It can control traction and energy transmission over a wide speed range by adjusting the current amplitude and "slip frequency." The stator can be a long stator (laid on the track), and the mover is mounted on the vehicle body. Both the stator and mover have windings and can be AC-excited separately. The traveling wave magnetic field can be a magnetic field waveform generated by multiphase AC current in the motor windings, moving along space at a certain speed. The stator's first and second traveling wave magnetic fields can be two independent traveling wave magnetic fields generated by dual-frequency stator power supply, with different frequencies and different spatial propagation speeds. Their characteristics are that their frequencies are independent, and their amplitude and phase can be independently controlled, thus forming a superimposed composite magnetic field in space. The electromechanical energy conversion can be the mutual conversion between electrical energy and mechanical energy, including but not limited to the adjustment of DFLM traction force, power supply, and normal force. Electromechanical energy conversion based on the first supply frequency under the first traveling wave magnetic field of the stator can be achieved by the interaction between the first traveling wave magnetic field of the stator and the current of the first supply frequency of the mover, generating specific traction force and normal force, and realizing energy transfer (feeding or feedback). Electromechanical energy conversion based on the second supply frequency under the second traveling wave magnetic field of the stator is similar. At least two control loops can be provided, meaning there are two independent power supply channels on the mover side, which can control the power supply parameters (amplitude, phase, mode) of the first and second supply frequencies respectively, to realize dual-frequency electromechanical energy conversion. Each control loop can realize dual-frequency electromechanical energy conversion, and each supply frequency can operate in subsynchronous traction or supersynchronous braking mode.

[0030] It should be noted that the stator dual-frequency power supply process provided in this embodiment can be referred to Figure 2 , Figure 2 This is a schematic diagram of the stator dual-frequency power supply provided in Embodiment 2 of the dual-frequency power supply system applicable to DFLM of this application; as shown Figure 2 As shown, the long stator of the DFLM (i.e., the stator itself) contains two traveling wave magnetic fields, which can be represented by the stator current vector. and This indicates that their respective motion frequencies are respectively and ,and .like Then the dual-frequency power supply of the stator degenerates into a single-frequency power supply.

[0031] It should be noted that, in Figure 2 In the diagram, and The positive direction of motion is defined as to the right, which is the direction of the motion of the mover. However, their respective motion frequencies... and Possibly positive or negative means and These two traveling wave magnetic fields can move either in the direction of the mover's forward movement or in the direction of the mover's backward movement.

[0032] Reference Figure 3 , Figure 3 This application provides a schematic diagram of a DFLM system with a mover containing two control loops, as shown in Embodiment 1 of a dual-frequency power supply system applicable to DFLMs. Considering, for example... Figure 3 The complete DFLM system shown can simultaneously sense the dual-frequency power supply magnetic field from the stator side on the mover side within each control loop. Therefore, reasonable control can be implemented on the mover side to achieve the desired effect of dual-frequency electromechanical energy conversion. For the DFLM mover, under dual-frequency stator power supply, the mover's magnetic flux vector... The equation can be expressed as:

[0033] in, For the self-sensory perception of the mover, The mutual inductance between stationary and moving parts. The moving part excitation current vector, and These are the phase numbers of the stationary and moving units, respectively.

[0034] Assuming the air gap permeability is , For the moving phase magnetizing inductor, we have:

[0035] For the mutual inductance between stationary and moving parts:

[0036] and These are the equivalent number of turns of the stator and mover windings, respectively. and The phase numbers of the stationary and moving parts are respectively. For the leakage of the moving part, and has .

[0037] Furthermore, the mover flux linkage vector can be expressed as:

[0038] in, For winding reduction factor, It is a synchronous inductor.

[0039] To achieve independent electromechanical energy conversion at both frequencies, dual-frequency excitation can also be introduced on the mover side, and its flux linkage vector can be further expressed as:

[0040] Among them, The mover excitation current vector is decomposed into and have . excitation frequency and Related, have

[0041] excitation frequency and Related, have

[0042] in For the equivalent electrical frequency of the mechanical motion of the mover, there is

[0043] in The pole distance of the DFLM. The velocity of the DFLM mover.

[0044] It should be noted that the mover excitation current vector in this embodiment... and It can be independently adjusted to complete the same or different electromechanical energy conversion tasks. Because the DFLM has phase freedom, the mover excitation current vector... and Both can independently adjust traction force and normal force. Therefore, by adopting dual-frequency power supply and combining the adjustment freedom of slip frequency, the degrees of freedom for traction force, normal force, and feed power in DFLM are greatly enriched. It can even break the strong constraint relationship between traction force and feed power in traditional DFLM control, thus adapting to different application scenarios. Different traction force, normal force, and feed power adjustment methods can be adopted based on different application scenarios.

[0045] Furthermore, the dual-frequency power supply system used in this embodiment for DFLM can be applied to stationary, natural deceleration, slow driving (coasting), slow acceleration and slow deceleration conditions of wheel-rail transportation. In the aforementioned rail transit scenario, only the adjustment of traction force and power supply is considered, while the adjustment of normal force is not considered.

[0046] The dual-frequency power supply system suitable for DFLM can also be applied to the static levitation, natural deceleration, slow driving (coasting), slow acceleration and slow deceleration conditions of high-speed maglev transportation. In the high-speed maglev transportation scenario, the adjustment of traction force, power supply, and normal force needs to be considered.

[0047] like Figure 3 As shown, to adapt to different application scenarios and purposes, the moving subunit can be divided into a front half and a rear half (corresponding to the first and second moving subunits), each using its own independent control loop for electromechanical energy conversion control. For the front half of the moving subunit, i.e., the first moving subunit (denoted by the subscript F), its flux linkage vector is further expressed as:

[0048] For the second half of the moving subunit, namely the second moving subunit (denoted by the subscript R), its flux linkage vector is further expressed as:

[0049] For maglev applications at speeds of 600 km / h or higher, the shortcomings of the existing LLSM system, such as the vehicle-track "phase coupling," dynamic coupling of levitation and traction control, and vehicle power supply technology, become potential constraints to speed improvement. Compared with the existing LLSM system, the "DFLM-QSO" has integrated traction, levitation, and power supply capabilities, and has advantages in vehicle-track "frequency coupling" and dynamic decoupling of levitation and traction. However, under certain special operating conditions (when there is no reaction force or the reaction force is insufficient), there is a bottleneck in power supply.

[0050] This embodiment intends to use the DFLM dual-frequency power supply method proposed above to specifically analyze the special working conditions of high-speed maglev applications. However, in wheel-rail transit applications, the adjustment of normal force can be disregarded.

[0051] It should be noted that the application scenarios in this embodiment include: power supply implementation under static buoyancy conditions. Static buoyancy is a very special application condition. In static buoyancy, no traction force is required, and the speed of the mover is... However, in the case of static levitation, the stator and mover of the DFLM used in maglev trains are still non-contact, so the mover side still needs to be powered through non-contact power supply.

[0052] The requirements for static buoyancy are: 1. Traction force 2. Possesses normal force adjustment capability; 3. Possesses power supply adjustment capability. This embodiment adopts the above-mentioned DFLM dual-frequency power supply method to meet the requirements of static buoyancy operation. Specifically, based on the above-mentioned DFLM dual-frequency power supply method, the stator current is set as follows:

[0053]

[0054] in, and These are the stator current vectors. and The amplitude, at this time their amplitude is .

[0055] From the mover side, two slip frequencies can be sensed. and Then we have:

[0056]

[0057] On the moving side and For example, configure it to the traction adjustment working mode (note that it can also be configured to...). and (Configured for traction force adjustment, the principle is the same). Oriented by the stator magnetic field (current vector) Electromechanical energy transformation analysis is performed using a coordinate system, where the first half of the moving sub-unit is based on... Orientation, for Coordinate system; the second half moving sub-unit is based on Orientation, for Coordinate system, such as Figure 4 As shown, Figure 4 This application provides a stator current-oriented dual-frequency power supply system embodiment one applicable to DFLM. A schematic diagram of dual-frequency excitation in a coordinate system; where... Figure 4 In this context, 'a' represents the first half of the moving subunit. Figure 4 In the figure, 'b' represents the second half-motor unit, and the stator current vector. and The included angle for:

[0058] in, This is the initial included angle. Simultaneously, and The amplitude is configured as follows:

[0059] At this moment, the traction force of the front and rear halves of the moving subunit is:

[0060]

[0061] at this time For traction force, This is the braking force. The traction force and braking force cancel each other out, thus satisfying the following:

[0062] It can be seen that the traction force of the front and rear halves of the unit can be offset to meet the requirements. The conditions were met. At the same time, the feasibility of power supply regulation was provided.

[0063] However, in Figure 4 The stator current vector is shown in the operating current mode. A normal force will be generated on the first half of the moving subunit. This normal force is an additional force... Fluctuating forces; similarly, the stator current vector. The latter half of the moving subunit will generate [a certain type of element]. Fluctuating normal force. To eliminate the fluctuating normal force of the front and rear moving sub-units, a weak magnetic current needs to be introduced into each half of the moving sub-unit. That is, a weak magnetic current is introduced into the front half of the moving sub-unit. Adjusting the fluctuation of the normal force, introduced in the rear half-motion sub-unit Adjusting fluctuations in normal force, such as Figure 5 As shown, Figure 5 This is a schematic diagram of dual-frequency excitation with the introduction of a field-weakening current vector, provided as an embodiment of the dual-frequency power supply system applicable to DFLM in this application. and Set to:

[0064]

[0065] Therefore, the normal forces in the first and second halves of the unit can be expressed as follows:

[0066]

[0067]

[0068]

[0069] It is evident that the normal forces in the first and second halves of the unit are equal at this point, and the fluctuation of the normal force has been eliminated. Furthermore, it can be achieved through… The magnitude of the amplitude is used to adjust the normal force to meet the requirements of static buoyancy.

[0070] After introducing a weak magnet on the mover side, the final traction force of the front and rear halves of the unit can be expressed as:

[0071]

[0072]

[0073]

[0074] At this time, there are still For traction force, This is the braking force. The traction force and braking force cancel each other out, thus achieving:

[0075] This satisfies the requirements of static buoyancy operation.

[0076] Meanwhile, the slip frequency of the first half of the unit The slip frequency of the second half of the unit Therefore, the first half of the unit operates in DFLM subsynchronous mode; the second half operates in DFLM supersynchronous mode. When the resultant traction force is zero, both the first and second half of the moving subunit can be powered by their respective traction forces.

[0077] It can be seen that the slip power includes a steady-state component and a fluctuating component, and its average value is:

[0078] Note that the negative sign here is defined as the injection of energy from the follower into the air gap. This means that energy is transferred from the stator side to the mover side. And it can be achieved through... and The magnitude of the slip power is adjusted to meet the requirements of static buoyancy operation. 3. The slip power can be regarded as the power supply.

[0079] The fluctuation component of slip power is:

[0080] The frequency of this fluctuation component is The fluctuation frequency of this part can be filtered by the DC bus capacitor and then transmitted to the vehicle power grid.

[0081] Under static buoyancy conditions, the motion flux linkage vector equations for the first and second halves of the motion element can be simplified to:

[0082]

[0083] It can be seen that the magnetic field of the first half of the mover unit is mainly the magnetic field of the first power supply frequency, while the magnetic field of the second half of the mover unit is mainly the magnetic field of the second power supply frequency. Based on this flux linkage equation, the voltage vector and current control of the mover can be further analyzed.

[0084] Note that in rail transit applications, the introduction of a weak magnetic current vector for normal force fluctuation regulation can be disregarded.

[0085] It should be noted that the application scenario in this embodiment also includes: power supply implementation under natural deceleration (traction force is 0) of high-speed maglev trains. Natural deceleration is also an important operating condition for maglev vehicles, used for maglev vehicles entering stations. Under natural deceleration conditions, since no braking force is required (traction force is 0), but the vehicle still has a certain speed. At this point, the stator and mover of the DFLM are still not in contact, so the mover side still needs to be powered by non-contact power supply.

[0086] Specifically, the requirements for natural deceleration are: 1. Traction force 2. Possesses normal force adjustment capability; 3. Possesses power supply adjustment capability. This embodiment adopts the DFLM dual-frequency power supply method proposed above to meet the requirements of static buoyancy operation. If the vehicle has a certain speed, the requirements of natural deceleration operation are the same as those of static buoyancy operation. Under natural deceleration operation, the stator current is configured as follows:

[0087]

[0088]

[0089] From the mover side, two slip frequencies can be sensed. and Then we have:

[0090]

[0091] Still using the former half-moving subunit Orientation, for Coordinate system (with the mover as the reference); the second half of the mover unit is based on... Orientation, for Coordinate system, its orientation principle and Figure 4 Consistent. Among them, the stator current vector... and The included angle is still for:

[0092] Still on the moving side and Configured for traction adjustment operation mode, and introduced in the front half of the moving subunit. Adjusting the fluctuation of the normal force, introduced in the rear half-moving sub-unit Adjusting the fluctuation of the normal force, and Figure 5 Consistent. The analysis under natural deceleration condition is consistent with that under static buoyancy condition. It can meet the requirements of deceleration condition 1-3.

[0093] It should be noted that in rail transit applications, the introduction of a weak magnetic current vector for normal force fluctuation regulation can be disregarded.

[0094] It should be noted that the application scenario in this embodiment also includes: power supply implementation under coasting or slow acceleration conditions. Under coasting or slow acceleration conditions, a smaller traction force is often required, which necessitates... However, due to the limitation of the slip frequency, sufficient power cannot be provided at this time. Meanwhile, a certain vehicle speed is required during coasting or slow acceleration. .

[0095] The requirements for coasting or slow acceleration are: 1. A small traction force with adjustable capability; 2. Adjustable normal force; 3. Adjustable power supply. This embodiment adopts the aforementioned DFLM dual-frequency power supply method to meet the requirements for coasting or slow acceleration. Specifically, the stator current is configured as follows:

[0096]

[0097]

[0098] Still on the moving side and Configured to traction adjustment mode, and Configured as a weak magnetic current to regulate fluctuations in the normal force, see reference. Figure 6 , Figure 6 This is a schematic diagram of the current configuration under coasting or slow acceleration conditions provided in Embodiment 1 of the dual-frequency power supply system applicable to DFLM in this application. Figure 6 In this context, 'a' represents the first half of the moving subunit. Figure 6 In this context, 'b' represents the second half of the moving subunit. and Configured as follows:

[0099]

[0100] First, let's analyze the normal force. Due to the presence of a weak magnetic field, the normal force in the first and second halves of the unit can be represented as follows:

[0101]

[0102]

[0103]

[0104] Under steady-state conditions, the normal forces of the front and rear moving sub-units must be equal. Then we have:

[0105] because Therefore, the stator current does not play a dominant role in the normal force; the normal force is mainly provided by the mover excitation. and The amplitudes are roughly the same. Because ,therefore amplitude Slightly smaller amplitude .in and The amplitude can be used to adjust the normal force to meet the requirements of coasting or slow acceleration conditions.

[0106] Next, we analyze the traction force. The traction forces of the front and rear units are as follows:

[0107]

[0108]

[0109]

[0110] At this time there is For traction force, This is the braking force. The traction force and braking force cancel each other out, thus satisfying the following:

[0111] because , Therefore:

[0112] Therefore, by using traction and braking forces to cancel each other out, a smaller traction force can be provided, and the average value of the pulling force is:

[0113] At the same time, it can be adjusted and Amplitude (mainly adjusting amplitude difference) Adjust the traction demand to meet the requirements of coasting or slow acceleration conditions.

[0114] At this point, the fluctuation in traction force is:

[0115] During coasting or slow acceleration, the traction requirement is not high, therefore and The amplitudes are also relatively close, so the traction fluctuations have little impact on the maglev train.

[0116] Meanwhile, the slip frequency of the first half of the unit The slip frequency of the second half of the unit Therefore, the first half of the unit operates in subsynchronous mode; the second half operates in supersynchronous mode. Both the first and second half of the moving subunit can be powered by their respective traction forces.

[0117]

[0118] It can be seen that the slip power includes a steady-state component and a fluctuating component, and its average value is:

[0119] It can be adjusted and Amplitude (mainly adjust amplitude and )and Adjust the slip power demand to meet the requirements of coasting or slow acceleration conditions. This means that energy can be transferred from the stator side to the mover side.

[0120] The fluctuation component of slip power is:

[0121] The frequency of this fluctuation component is The fluctuation frequency of this part can be filtered by the DC bus capacitor and then transmitted to the vehicle power grid.

[0122] Similarly, under coasting or slow acceleration conditions, the motion flux linkage vector equations for the first and second halves of the motion element can be simplified to:

[0123]

[0124] It should be noted that the application scenarios in this embodiment also include: power supply implementation under slow deceleration (small braking force deceleration).

[0125] Under slow deceleration conditions, a negative traction force (braking force) is required to achieve the purpose of slow deceleration, and the amplitude of this braking force is relatively small.

[0126] The requirements for slow deceleration are: 1. To provide a small braking force with adjustable capability; 2. To have adjustable normal force; 3. To have adjustable power supply. This embodiment adopts the DFLM dual-frequency power supply method proposed above to meet the requirements of coasting or slow acceleration. Specifically, in slow deceleration, the stator current only needs to be configured as follows:

[0127]

[0128] Still on the moving side and Configured to traction adjustment mode, and Configured as a weak magnetic current:

[0129]

[0130] Then it can be satisfied:

[0131] This satisfies the requirements for slow deceleration conditions. Other analyses under slow deceleration conditions are consistent with those under coasting conditions. It meets requirements 1-3 for slow deceleration conditions.

[0132] Note that in rail transit applications, the introduction of a weak magnetic current vector for normal force fluctuation regulation can be disregarded.

[0133] This embodiment further refers to the application requirements of high-speed maglev, and performs finite element simulation of a moving subunit of a high-speed maglev train, building a finite element DFLM model as follows. Figure 7 As shown, Figure 7 This is a schematic diagram of a finite element DFLM model provided in Embodiment 1 of the dual-frequency power supply system applicable to DFLM in this application; it is a DFLM with a three-phase stator and a dual five-phase mover, with the upper part being the long stator of the DFLM and the lower part being the mover of the DFLM, containing two control units. The basic parameters of this model are shown in Table 1 - DFLM simulation parameter table: Table 1 - DFLM Simulation Parameters

[0134] This embodiment analyzes three control methods for static (stationary) or natural deceleration conditions, specifically: 1. Using traditional control methods, under static (stationary) or natural deceleration conditions, the longitudinal load of the DFLM is almost zero, therefore the traction force it provides is limited. It is also close to 0, according to the slip power equation of DFLM:

[0135] With limited mover voltage, the mover side also cannot provide a large slip. The power supply that can be provided using traditional methods .

[0136] 2. Simulation results for adjusting the motor side using dual-frequency excitation without applying a normal force are as follows: Figure 8 As shown, Figure 8 This is a schematic diagram of the current configuration under coasting or slow acceleration conditions provided in Embodiment 1 of the dual-frequency power supply system applicable to DFLM of this application; it can be seen that under dual-frequency application, the stator current is a standing wave, such as... Figure 8 As shown in Figure (a), i in Figure (a) sA i sB i sC These are the three-phase stator currents. At this time, the first control circuit of the mover is powered by the first supply frequency, without applying a field-weakening current; the second control circuit of the mover is powered by the second supply frequency, without applying a field-weakening current. Therefore, the mover currents in the first and second control circuits are equalization currents, such as... Figure 8 Figure (c) and Figure 8 As shown in Figure (d), where i ra i rb i rc i rd and i re These represent the current in each of the five phases. Since no weak magnetic current is applied to the mover side to adjust the normal force, the normal force of the mover exhibits large fluctuations, such as... Figure 8 As shown in Figure (f). Under this control method, dual-frequency power supply is used, and the traction force is very small (traction force) The average value is 0, and its slight fluctuation is due to the cogging effect of the stator and mover. This achieves the output of the feed power, where the average feed power is 9.7kW. Figure 8 Figure (e) and Figure 8As shown in Figure (b), it can be seen that by using dual-frequency excitation of the DFLM, the problem of maintaining or controlling the slip power under the condition of under-reaction force of the DFLM can be solved. This control method without applying a weak magnetic current is suitable for the stationary or natural deceleration conditions of rail transit applications.

[0137] 3. Using dual-frequency excitation (the stator is excited by two currents of different frequencies, generating two traveling wave magnetic fields), the result of applying normal force to the mover side is as follows: Figure 9 As shown, Figure 9 This is a schematic diagram illustrating the results of dual-frequency excitation and field weakening adjustment applied to the mover side, as provided in Embodiment 1 of the dual-frequency power supply system applicable to DFLM in this application. It can be seen that under dual-frequency excitation, the stator current still exhibits a standing wave pattern, as shown below. Figure 9 As shown in Figure (a), the first control circuit of the mover uses the first power supply frequency to achieve electromechanical energy conversion, and further utilizes the second power supply frequency to weaken the second traveling wave magnetic field of the stator; the second control circuit of the mover uses the second power supply frequency to achieve electromechanical energy conversion, and further utilizes the first power supply frequency to weaken the first traveling wave magnetic field of the stator. Therefore, the mover current in both the first and second control circuits is a superposition of the first and second power supply frequencies, thus exhibiting unbalanced characteristics, such as... Figure 9 Figure (c) and Figure 9 As shown in Figure (d), because a weak magnetic current is applied to the mover side to adjust the normal force, the fluctuation of the mover normal force is greatly reduced, as shown in Figure (d). Figure 9 As shown in Figure (f). Under this control method, dual-frequency power supply is used, except in the case of very low traction force (traction force). The average value is 0, and its slight fluctuation is due to the cogging effect of the stator and mover. This achieves the output of the feed power, where the average feed power is 9.8kW. Figure 9 Figure (e) and Figure 9 As shown in Figure (b), the fluctuation of the normal force is eliminated by introducing the adjustment of the normal force. This dual-frequency excitation control method without applying a weak magnetic current is suitable for static levitation or natural deceleration conditions in high-speed maglev transportation applications.

[0138] This embodiment of the DFLM includes a stator and a mover. The stator employs dual-frequency power supply, comprising two independent first traveling wave magnetic fields and a second traveling wave magnetic field. The current amplitude and phase of the stator's dual-frequency power supply are independently adjustable. The mover also employs dual-frequency power supply, with its first power supply frequency synchronized with the first traveling wave magnetic field and its second power supply frequency synchronized with the second traveling wave magnetic field. The current amplitude and phase of the mover's dual-frequency power supply are independently adjustable. Electromechanical energy conversion is performed based on the first power supply frequency under the first traveling wave magnetic field and based on the second power supply frequency under the second traveling wave magnetic field. The mover includes at least two control loops, which are used to realize the dual-frequency power supply electromechanical energy conversion. Compared to existing methods that rely on the product of a single slip frequency and traction force to obtain slip power, this application increases the degree of freedom in adjusting traction force and slip power.

[0139] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the application of this application to dual-frequency power supply systems for DFLM. Any simple modifications based on this technical concept are within the protection scope of this application.

[0140] This application also provides a dual-frequency power supply method suitable for DFLM, the method being applied to the aforementioned dual-frequency power supply system suitable for DFLM, the method comprising: The DFLM includes a stator and a mover; The stator is powered by dual frequency, and the stator includes two independent first traveling wave magnetic fields and second traveling wave magnetic fields. The current amplitude and phase of the stator powered by dual frequency are independently adjustable. The mover is powered by a dual-frequency power supply. The first power supply frequency of the mover is synchronized with the first traveling wave magnetic field, and the second power supply frequency of the mover is synchronized with the second traveling wave magnetic field. The current amplitude and phase of the dual-frequency power supply of the mover are independently adjustable. Under the first traveling wave magnetic field, electromechanical energy conversion is performed based on the first power supply frequency; Under the second traveling wave magnetic field, electromechanical energy conversion is performed based on the second power supply frequency; The mover includes at least two control loops, which are used to realize dual-frequency power supply electromechanical energy conversion.

[0141] The dual-frequency power supply method for DFLM provided in this application, applied to the dual-frequency power supply system for DFLM in the above embodiments, can solve the technical problem of insufficient freedom in existing slip power control. Compared with the prior art, the beneficial effects of the dual-frequency power supply method for DFLM provided in this application are the same as the beneficial effects of the dual-frequency power supply system for DFLM provided in the above embodiments, and other technical features in the dual-frequency power supply method for DFLM are the same as those disclosed in the above embodiments, and will not be repeated here.

[0142] The above description is only a part of the embodiments of this application and does not limit the scope of protection of this application. All equivalent structural transformations made under the technical concept of this application and using the content of this application specification and drawings, or direct / indirect applications in other related technical fields, are included in the scope of protection of this application.

Claims

1. A dual-frequency power supply system suitable for a doubly-fed linear motor, characterized in that, The doubly fed linear motor includes a stator and a mover; The stator is powered by dual frequency, forming two independent first traveling wave magnetic fields and second traveling wave magnetic fields on the stator. The current amplitude and phase of the stator powered by dual frequency are independently adjustable. The mover is powered by a dual-frequency power supply. The first power supply frequency of the mover is synchronized with the first traveling wave magnetic field of the stator, and the second power supply frequency of the mover is synchronized with the second traveling wave magnetic field of the stator. The current amplitude and phase of the dual-frequency power supply of the mover are independently adjustable. Under the first traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the first power supply frequency; Under the second traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the second power supply frequency; The mover includes at least two control loops, which respectively perform dual-frequency power supply electromechanical energy conversion, increasing the overall electromechanical energy conversion control freedom of the doubly fed linear motor; The electromechanical energy control and transformation includes, but is not limited to, the adjustment of the traction force, power supply, and normal force of the doubly fed linear motor.

2. The dual-frequency power supply system for a doubly-fed linear motor according to claim 1, characterized in that, The control loop is used to independently adjust the amplitude and direction of the traction force; The combined control of the control loop is used to meet the adaptability of the doubly fed linear motor to traction conditions. The control circuit included in the doubly fed linear motor mover is used to independently adjust the magnitude and phase of traction force fluctuations, and the overall traction force fluctuations of the doubly fed linear motor are offset by the combination of various control circuits.

3. The dual-frequency power supply system for a doubly-fed linear motor according to claim 1, characterized in that, The control circuits included in the doubly fed linear motor mover each operate independently in subsynchronous traction mode or supersynchronous braking mode, and control the power supply from the stator side to the mover side through the combination of the various control circuits. When all control circuits of the doubly fed linear motor share a common DC bus, a DC bus capacitor is used to filter the fluctuations in the power supply. When the control circuits of the doubly fed linear motor do not share a DC bus, a separate DC bus capacitor is set on the independent DC bus of each circuit to filter the power fluctuations of each circuit.

4. The dual-frequency power supply system for a doubly-fed linear motor according to claim 1, characterized in that, The first or second power supply frequency is used for electromechanical energy conversion, which includes traction force and power supply control. Another power supply frequency is used to weaken the traveling wave magnetic field of the stator at the corresponding frequency, or to regulate the fluctuation of the normal force.

5. The dual-frequency power supply system for a doubly-fed linear motor according to claim 4, characterized in that, The combination of the various control loops is used to adjust the overall normal force requirement of the doubly fed linear motor; The combination of the various control loops is used to regulate the overall normal force fluctuation of the doubly fed linear motor.

6. The dual-frequency power supply system for a doubly-fed linear motor according to any one of claims 1-5, characterized in that, The system is applied to stationary, natural deceleration, slow movement, slow acceleration, and slow deceleration conditions in wheel-rail transportation. In the aforementioned rail transit scenario, the traction force and power supply are adjusted based on the control loop, without considering the adjustment of the normal force.

7. The dual-frequency power supply system for a doubly-fed linear motor according to any one of claims 1-5, characterized in that, The system is applied to the static levitation, natural deceleration, slow driving, slow acceleration and slow deceleration conditions of high-speed maglev transportation. In the high-speed maglev transportation scenario, the traction force, power supply, and normal force are adjusted based on the control loop.

8. The dual-frequency power supply system for a doubly-fed linear motor according to claim 6 or 7, characterized in that, Under the conditions of static or static buoyancy and natural deceleration, the current amplitudes corresponding to the first and second stator power supply frequencies are equal, and the stator's dual-frequency power supply frequency... and They are respectively: in Used for regulating the power supply. The electrical frequency corresponding to the vehicle speed; The mover includes a first mover unit and a second mover unit, and is independently controlled by a first control loop and a second control loop. The first power supply frequency of the first mover unit is subsynchronous traction, and the second power supply frequency is a field weakening frequency. The second power supply frequency of the second mover unit is supersynchronous braking, and the first power supply frequency is a field weakening frequency. Alternatively, a combination configuration can be provided where the first moving subunit is for subsynchronous traction and the second moving subunit is for supersynchronous braking; In the high-speed maglev transportation scenario, the amplitude of the mover current corresponding to the subsynchronous traction and supersynchronous braking modes is the normal force that meets the levitation requirements. The weak magnetic current vector corresponding to the mover is opposite to the corresponding stator current vector, and their ratio is the winding reduction coefficient. In the context of rail transit, the adjustment of normal force is not considered.

9. The dual-frequency power supply system for a doubly-fed linear motor according to claim 6 or 7, characterized in that, Under conditions of slow driving, coasting, slow acceleration, or slow deceleration, the current amplitudes corresponding to the first and second stator power supply frequencies are not equal, and the stator's dual-frequency power supply frequency... and They are respectively: in Used for regulating the power supply. The electrical frequency corresponding to the vehicle speed; The mover includes a first mover unit and a second mover unit, and is independently controlled by a first control loop and a second control loop. The first power supply frequency of the first mover unit is subsynchronous traction, and the second power supply frequency is a field weakening frequency. The second power supply frequency of the second mover unit is supersynchronous braking, and the first power supply frequency is a field weakening frequency. Alternatively, it can be a combination configuration where one moving subunit is for subsynchronous traction and the other moving subunit is for supersynchronous braking; In the high-speed maglev transportation scenario, the amplitude of the mover current corresponding to the subsynchronous traction and supersynchronous braking modes is the normal force that meets the levitation requirements. The weak magnetic current vector corresponding to the mover is opposite to the corresponding stator current vector, and their ratio is the winding reduction coefficient. In the context of rail transit, the adjustment of normal force is not considered.

10. A dual-frequency power supply method suitable for a doubly-fed linear motor, characterized in that, The method is applied to a dual-frequency power supply system suitable for a doubly-fed linear motor as described in any one of claims 1 to 9, and the method includes: The doubly fed linear motor includes a stator and a mover; The stator is powered by dual frequency, forming two independent first traveling wave magnetic fields and second traveling wave magnetic fields on the stator. The current amplitude and phase of the stator powered by dual frequency are independently adjustable. The mover is powered by a dual-frequency power supply. The first power supply frequency of the mover is synchronized with the first traveling wave magnetic field of the stator, and the second power supply frequency of the mover is synchronized with the second traveling wave magnetic field of the stator. The current amplitude and phase of the dual-frequency power supply of the mover are independently adjustable. Under the first traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the first power supply frequency; Under the second traveling wave magnetic field of the stator, electromechanical energy conversion is performed based on the second power supply frequency; The mover includes at least two control loops, which respectively perform dual-frequency power supply electromechanical energy conversion, increasing the overall electromechanical energy conversion control freedom of the doubly fed linear motor; The electromechanical energy control and transformation includes, but is not limited to, the adjustment of the traction force, power supply, and normal force of the doubly fed linear motor.

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