High-power synchronous motor excitation device and control method

Abstract

The invention discloses a high-power synchronous motor excitation device and a control method. The high-power synchronous motor excitation device comprises a multi-pulse excitation transformer, a plurality of three-phase PWM rectifiers, a field suppression circuit and a multi-phase interleaved parallel bidirectional DC-DC converter, wherein the direct current sides of the three-phase PWM rectifiers are connected in parallel; aC side LCL filters of the three-phase PWM rectifiers are connected with windings of the secondary side of the excitation transformer in a one-to-one correspondence manner, and DC sides of the three-phase PWM rectifiers are connected in parallel to form a DC bus; the bidirectional DC-DC converter can quickly, accurately and stably adjust direct-current excitation in a wide range, and provides additional excitation damping to control and suppress low-frequency oscillation of a power system; positive damping electromagnetic torque is provided by adjusting terminal voltage of the synchronous motor, low-frequency oscillation of the power system is suppressed, and stability of the power system is improved. Energy stored by the magnet exciting coil is directly fed back to a power grid through the bidirectional DC-DC converter and the PWM rectifier, and the field suppression circuit is started, so that efficient, rapid and reliable field suppression is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of motors, and relates to an excitation device and a control method for a high-power synchronous motor. Background Art

[0002] Thyristor rectifiers are widely used in generator excitation systems to provide fast excitation. Fast excitation and its control provide a powerful and important means to improve the safety and stability of power systems. For example, the use of excitation control technologies such as Power System Stabilizer (PSS) and enhanced additional excitation damping control (SEDC) can not only suppress subsynchronous low-frequency oscillations, but also improve the operating stability and anti-interference ability of power systems, and have been widely used.

[0003] Due to the semi-controlled characteristics of thyristor switching devices, each thyristor switching device can only be turned on and off once in each power grid power frequency voltage cycle. Its switching frequency is low and its response to control signals is slow. According to Shannon's theorem, the Nyquist frequency of the excitation system is only half of the power grid power frequency. Therefore, when dealing with system short-circuit faults and other application scenarios that require the excitation system to force excitation or increase excitation, the excitation system cannot provide fast and powerful excitation regulation, which can easily lead to the expansion of power system accidents. In addition, the excitation current is generated and adjusted by changing the trigger delay angle of the thyristor, and the resulting low-frequency excitation current ripple is large, which will cause low-frequency fluctuations in the excitation magnetic field and electromagnetic torque of the motor, thereby adversely affecting the safe and stable operation of the motor system. The use of bulky power frequency smoothing inductors can reduce but cannot effectively eliminate the low-frequency disturbances of the excitation current. Since the excitation device based on thyristor rectifier cannot provide fast, accurate and smooth excitation regulation, even if excitation control methods such as PSS are used to adjust the electromagnetic torque of the motor and enhance the positive damping of the system, it is difficult to quickly and effectively suppress the low-frequency / ultra-low-frequency oscillation of 0.1Hz~3Hz of the synchronous generator terminal voltage.

[0004] In addition, since the electromagnetic torque of the motor is generated by the interaction between the rotor excitation magnetic field and the stator magnetic field, a machine-side subsynchronous damping controller based on a static VAR compensator (STATCOM) can be added to provide fast current compensation on the stator side of the generator. The rotor excitation system and the machine-side STATCOM can work together to quickly adjust the electromagnetic torque to enhance the forward damping of the motor system, effectively suppress low-frequency / ultra-low-frequency oscillations, and further improve the stability of the power system. However, adding a machine-side subsynchronous damping controller based on STATCOM will significantly increase the hardware cost of the system.

[0005] The existing excitation system based on thyristor rectifier cannot meet the requirements of safe and stable operation of modern power system, and its control and regulation performance and economy need to be improved urgently. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a high-power synchronous motor excitation device and control method, so as to improve the performance and function of the excitation system and effectively reduce the cost, volume and weight of the excitation system.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a high-power synchronous motor excitation device, which includes a multi-pulse excitation transformer, a parallel PWM rectifier circuit, an interlaced parallel bidirectional DC-DC converter and a demagnetization circuit; the parallel PWM rectifier circuit is electrically connected to the DC side of the multi-pulse excitation transformer, the interlaced parallel bidirectional DC-DC converter and the demagnetization circuit are electrically connected to the parallel PWM rectifier circuit, and the excitation winding is electrically connected to the interlaced parallel bidirectional DC-DC converter; the parallel PWM rectifier circuit is composed of a plurality of three-phase PWM high-frequency rectifiers.

[0008] The capacity of the multi-pulse excitation transformer is a 6-, 12-, 18-, 24- or 30-pulse transformer.

[0009] The primary side of the multi-pulse excitation transformer is a group of three-phase windings, and each group of three-phase windings on the secondary side is connected to a three-phase PWM high-frequency rectifier.

[0010] The capacity of the three-phase PWM high-frequency rectifier is a 2-, 3- or 5-level three-phase fully controlled device bridge circuit; the DC sides of the three-phase PWM high-frequency rectifiers are connected in parallel to form a DC bus.

[0011] The three-phase two-level PWM rectifiers of the three-phase PWM high-frequency rectifier all adopt dual-loop control, including a DC bus voltage control outer loop and an AC side input current control inner loop.

[0012] The input end of the staggered parallel bidirectional DC-DC converter is connected to the DC bus, and the output end is connected to the excitation coil.

[0013] The capacity of the staggered parallel bidirectional DC-DC converter is a 2-, 3- or 5-level bidirectional bridge circuit, and the number of parallel staggered H-bridge circuits is adjustable; the input end of the demagnetization circuit is connected to the DC bus.

[0014] In the control method of the high-power synchronous motor excitation device as described above, the three-phase PWM high-frequency rectifier adopts a DC voltage outer loop control to provide the set DC bus voltage, and the more pulses the excitation transformer has, the higher the ripple frequency of the DC bus voltage and the smaller the fluctuation; the three-phase PWM high-frequency rectifier adopts a conventional grid-connected industrial frequency current control strategy to ensure that the AC side grid-connected current is sinusoidal and the power factor is adjustable; the three-phase PWM high-frequency rectifier also adds a machine-end additional damping controller to detect and calculate the modal compensation current of the low-frequency oscillation signal, and then injects it into the machine end of the synchronous motor through the current inner loop control of the three-phase PWM high-frequency rectifier, thereby providing a positive damping electromagnetic torque to suppress low-frequency oscillation; in addition, the current inner loop of the three-phase PWM high-frequency rectifier adopts a current balancing measure, and the current balancing measure includes master-slave current balancing or droop current balancing, so as to realize that each parallel three-phase PWM high-frequency rectifier bears the transmission power on average, avoiding overload of individual rectifiers.

[0015] As described above, the control method of the high-power synchronous motor excitation device, the staggered parallel bidirectional DC-DC converter includes two working conditions: excitation control and de-excitation control; Under the excitation control condition, the interleaved parallel bidirectional DC-DC converter works in the buck mode, and adopts the excitation voltage controller, including the PI controller, to quickly reduce the DC bus voltage to the required excitation voltage; the interleaved parallel bidirectional DC-DC converter also adds an additional excitation damping controller to detect and calculate the modal compensation current of the low-frequency oscillation signal, and inject it into the excitation current of the synchronous motor, thereby providing positive damping electromagnetic torque to suppress low-frequency oscillation; in addition, the interleaved parallel bidirectional DC-DC converter adopts current balancing measures in the voltage loop to realize the average transmission power of each interleaved parallel H bridge, avoiding overload of individual H bridge circuits; Under the demagnetization control condition, the interleaved parallel bidirectional DC-DC converter works in the boost mode, and uses a current controller, including a PI controller, to quickly release the stored electric energy in the excitation coil and inject it into the DC bus, causing the DC bus voltage to rise dynamically; the rise in the DC bus voltage will, on the one hand, trigger the three-phase PWM high-frequency rectifier to automatically feed back the excitation electric energy to the grid, and on the other hand, when the DC bus voltage exceeds the preset threshold, the demagnetization resistor will be connected to the DC bus by closing the demagnetization switch, accelerating the demagnetization speed of the excitation coil by consuming the excitation electric energy; Similarly, the interleaved parallel bidirectional DC-DC converter adopts current balancing measures in the voltage loop to achieve that each interleaved parallel H-bridge bears the transmission power on average, avoiding overload of individual H-bridge circuits; Similarly, the interleaved parallel bidirectional DC-DC converter adopts current sharing measures to ensure that each interleaved parallel H-bridge bears the transmission power on average, thereby avoiding overload of individual H-bridge circuits.

[0016] It also includes four three-phase PWM high-frequency rectifiers connected in parallel on the DC side electrically connected to a 24-pulse excitation transformer, as well as a multi-phase interleaved parallel bidirectional high-frequency DC-DC converter and a demagnetization circuit.

[0017] The main beneficial effects of the present invention are: The more pulses the excitation transformer uses in the excitation device, the higher the ripple frequency of the DC bus voltage of the PWM rectifier and the smaller the fluctuation. Compared with the thyristor-based rectifier circuit, there is no need to use bulky power-frequency smoothing inductors, and the volume and weight are greatly reduced.

[0018] The AC side of each PWM rectifier is connected to a different secondary winding of the excitation transformer, thereby avoiding the occurrence of circulating current during the high-frequency commutation operation of each PWM rectifier.

[0019] The high-frequency switching PWM rectifier can not only adjust the DC bus voltage quickly, accurately, smoothly and over a wide range, but also inject oscillation mode compensation current into the machine end of the synchronous motor as needed without adding STATCOM, thereby quickly and accurately generating positive damping electromagnetic torque, suppressing low-frequency oscillations of the power system, and improving the stability of the power system.

[0020] The multi-phase interleaved parallel bidirectional DC-DC converter greatly improves the equivalent switching frequency of the input and output current by interleaving and paralleling. Compared with the thyristor-based excitation regulation circuit, it can not only quickly, accurately, stably and widely step down the DC bus voltage for excitation and improve the excitation control and regulation performance, but also greatly reduce its size and weight. When dealing with system short-circuit faults and other application scenarios that require the excitation system to force excitation or increase excitation, the excitation system can provide fast and powerful excitation regulation to prevent the expansion of power system accidents.

[0021] Under the demagnetization condition of the synchronous motor, the multi-phase interleaved parallel bidirectional DC-DC converter will switch to the boost working mode, quickly release the energy stored in the excitation coil in reverse and inject it into the DC bus side, and achieve efficient, fast and reliable demagnetization by combining the PWM rectifier energy feedback to the grid and the opening of the demagnetization circuit discharge consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] Figure 1 It is a structural schematic diagram of the present invention.

[0024] Figure 2 It is the wiring diagram of the multi-pulse excitation transformer of the present invention.

[0025] Figure 3 This is a control diagram of the present invention.

[0026] Figure 4 The present invention provides a wiring and control diagram for a staggered parallel two-level bidirectional DC-DC converter.

[0027] Figure 5 Another structural schematic diagram of the present invention.

[0028] In the figure: a multi-pulse excitation transformer 1; a parallel PWM rectifier circuit 2; an interleaved parallel bidirectional DC-DC converter 3; a demagnetization circuit 4; and an excitation winding 5. DETAILED DESCRIPTION

[0029] like Figure 1~Figure 5 A high-power synchronous motor excitation device is provided, which includes a multi-pulse excitation transformer 1, a parallel PWM rectifier circuit 2, an interlaced parallel bidirectional DC-DC converter 3 and a demagnetization circuit 4; the parallel PWM rectifier circuit 2 is electrically connected to the DC side of the multi-pulse excitation transformer 1, the interlaced parallel bidirectional DC-DC converter 3 and the demagnetization circuit 4 are electrically connected to the parallel PWM rectifier circuit 2, and the excitation winding 5 is electrically connected to the interlaced parallel bidirectional DC-DC converter 3; the parallel PWM rectifier circuit 2 is composed of a plurality of three-phase PWM high-frequency rectifiers.

[0030] Preferably, the AC-side LCL filters of each three-phase PWM high-frequency rectifier are connected to the secondary windings of the excitation transformer in a one-to-one correspondence, and their DC sides are connected in parallel to form a DC bus.

[0031] Preferably, the demagnetization circuit 4 includes a demagnetization switch and a demagnetization resistor connected to the DC bus.

[0032] In a preferred solution, the capacity of the multi-pulse excitation transformer 1 is a 6-, 12-, 18-, 24- or 30-pulse transformer.

[0033] Preferably, the more pulses the multi-pulse excitation transformer 1 has, the higher the ripple frequency of the DC-side bus voltage of the three-phase PWM high-frequency rectifier and the smaller the fluctuation. Compared with the thyristor-based rectifier circuit, there is no need to use bulky power-frequency smoothing inductors, and the volume and weight are greatly reduced.

[0034] In a preferred solution, the primary side of the multi-pulse excitation transformer 1 is a group of three-phase windings, and each group of three-phase windings on the secondary side is connected to a three-phase PWM high-frequency rectifier.

[0035] Preferably, the AC side of each three-phase PWM high-frequency rectifier is connected to different secondary windings of the excitation transformer, thereby avoiding the occurrence of circulating current during the high-frequency commutation operation of each PWM rectifier.

[0036] In a preferred solution, the capacity of the three-phase PWM high-frequency rectifier is a 2-, 3- or 5-level three-phase fully controlled device bridge circuit; the DC sides of the three-phase PWM high-frequency rectifiers are connected in parallel to form a DC bus.

[0037] In a preferred solution, the three-phase two-level PWM rectifiers of the three-phase PWM high-frequency rectifier all adopt dual-loop control, including a DC bus voltage control outer loop and an AC side input current control inner loop.

[0038] Preferably, the three-phase PWM high-frequency rectifier of the high-frequency switch can not only adjust the DC bus voltage quickly, accurately, stably and over a wide range, but also inject oscillation modal compensation current into the machine end of the synchronous motor as needed without adding STATCOM, thereby quickly and accurately generating positive damping electromagnetic torque, suppressing low-frequency oscillations of the power system, and improving the stability of the power system.

[0039] In a preferred solution, the input end of the staggered parallel bidirectional DC-DC converter 3 is connected to the DC bus, and the output end is connected to the excitation coil.

[0040] In a preferred solution, the capacity of the staggered parallel bidirectional DC-DC converter 3 is a 2-, 3- or 5-level bidirectional bridge circuit, and the number of parallel staggered H-bridge circuits is adjustable; the input end of the demagnetization circuit is connected to the DC bus.

[0041] Preferably, the multi-phase interleaved parallel bidirectional DC-DC converter 3 greatly improves the equivalent switching frequency of the input and output currents by means of interleaved parallel connection. Compared with the thyristor-based excitation regulation circuit, it can not only quickly, accurately, stably and widely step down the DC bus voltage for excitation use and improve the excitation control regulation performance, but also greatly reduce its size and weight. When dealing with system short-circuit faults and other application scenarios that require the excitation system to force excitation or increase excitation, the excitation system can provide fast and powerful excitation regulation to prevent the expansion of power system accidents.

[0042] In the preferred scheme, in the control method of the high-power synchronous motor excitation device as described above, the three-phase PWM high-frequency rectifier adopts a DC voltage outer loop control to provide the set DC bus voltage, and the more pulses the excitation transformer has, the higher the ripple frequency of the DC bus voltage and the smaller the fluctuation; the three-phase PWM high-frequency rectifier adopts a conventional grid-connected power frequency current control strategy to ensure that the AC side grid-connected current is sinusoidal and the power factor is adjustable; the three-phase PWM high-frequency rectifier also adds a machine-end additional damping controller to detect and calculate the modal compensation current of the low-frequency oscillation signal, and then injects it into the machine end of the synchronous motor through the current inner loop control of the three-phase PWM high-frequency rectifier, thereby providing a positive damping electromagnetic torque to suppress low-frequency oscillation; in addition, the current inner loop of the three-phase PWM high-frequency rectifier adopts a current balancing measure, and the current balancing measure includes master-slave current balancing or droop current balancing, so as to realize that each parallel three-phase PWM high-frequency rectifier bears the transmission power on average, avoiding overload of individual rectifiers.

[0043] In the above method, the interleaved parallel bidirectional DC-DC converter 3 can adjust the DC excitation quickly, accurately, stably and in a wide range, and provide additional excitation damping control to suppress low-frequency oscillation of the power system.

[0044] In the above method, the three-phase PWM high-frequency rectifier can not only increase the high DC bus voltage with low ripple, but also realize sinusoidal current input on the AC side with adjustable power factor, and can provide positive damping electromagnetic torque by adjusting the terminal voltage of the synchronous motor, thereby suppressing the low-frequency oscillation of the power system and improving the stability of the power system.

[0045] In the preferred solution, the control method of the high-power synchronous motor excitation device as described above, the staggered parallel bidirectional DC-DC converter 3 includes two working conditions: excitation control and de-excitation control; Under the excitation control condition, the interleaved parallel bidirectional DC-DC converter 3 works in the step-down mode, and adopts the excitation voltage controller, including the PI controller, to quickly reduce the DC bus voltage to the required excitation voltage; the interleaved parallel bidirectional DC-DC converter 3 also adds an additional excitation damping controller to detect and calculate the modal compensation current of the low-frequency oscillation signal, and inject it into the excitation current of the synchronous motor, thereby providing a positive damping electromagnetic torque to suppress the low-frequency oscillation; in addition, the interleaved parallel bidirectional DC-DC converter 3 adopts a current balancing measure in the voltage loop to realize that each interleaved parallel H bridge bears the average transmission power, thereby avoiding overload of individual H bridge circuits; Under the demagnetization control condition, the staggered parallel bidirectional DC-DC converter 3 works in the boost mode, and adopts a current controller, including a PI controller, to quickly release the stored electric energy in the excitation coil and inject it into the DC bus, causing the DC bus voltage to rise dynamically; the rise of the DC bus voltage will, on the one hand, trigger the three-phase PWM high-frequency rectifier to automatically feed back the excitation electric energy to the power grid, and on the other hand, when the DC bus voltage exceeds a preset threshold, the demagnetization resistor will be connected to the DC bus by closing the demagnetization switch, and the demagnetization speed of the excitation coil will be accelerated by consuming the excitation electric energy; Similarly, the interleaved parallel bidirectional DC-DC converter 3 adopts current balancing measures in the voltage loop to achieve that each interleaved parallel H bridge bears the transmission power on average, thus avoiding overload of individual H bridge circuits; Similarly, the interleaved parallel bidirectional DC-DC converter 3 adopts a current balancing measure to ensure that each interleaved parallel H bridge bears the transmission power on average, thereby avoiding overload of individual H bridge circuits.

[0046] In the above method, under the demagnetization condition of the synchronous motor, the multi-phase interleaved parallel bidirectional DC-DC converter 3 will switch to the boost working mode, quickly release the energy stored in the excitation coil in reverse and inject it into the DC bus side, and realize efficient, fast and reliable demagnetization by combining the PWM rectifier energy feedback to the power grid and the opening of the demagnetization circuit discharge consumption.

[0047] The preferred solution also includes four three-phase PWM high-frequency rectifiers connected in parallel on the DC side and electrically connected to a 24-pulse excitation transformer, as well as a multi-phase interleaved parallel bidirectional high-frequency DC-DC converter and a demagnetization circuit.

[0048] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A high-power synchronous motor excitation device, characterized in that: It comprises a multi-pulse excitation transformer (1), a parallel PWM rectifier circuit (2), an interlaced parallel bidirectional DC-DC converter (3) and a demagnetization circuit (4); the parallel PWM rectifier circuit (2) is electrically connected to the DC side of the multi-pulse excitation transformer (1), the interlaced parallel bidirectional DC-DC converter (3) and the demagnetization circuit (4) are electrically connected to the parallel PWM rectifier circuit (2), and the excitation winding (5) is electrically connected to the interlaced parallel bidirectional DC-DC converter (3); the parallel PWM rectifier circuit (2) is composed of a plurality of three-phase PWM high-frequency rectifiers.

2. The high-power synchronous motor excitation device according to claim 1 is characterized in that: The capacity of the multi-pulse excitation transformer (1) is a 6-, 12-, 18-, 24- or 30-pulse transformer.

3. The high-power synchronous motor excitation device according to claim 1 is characterized in that: The primary side of the multi-pulse excitation transformer (1) is a group of three-phase windings, and each group of three-phase windings on the secondary side is connected to a three-phase PWM high-frequency rectifier.

4. The high-power synchronous motor excitation device according to claim 3 is characterized in that: The capacity of the three-phase PWM high-frequency rectifier is a 2-, 3- or 5-level three-phase fully controlled device bridge circuit; the DC sides of the three-phase PWM high-frequency rectifiers are connected in parallel to form a DC bus.

5. The high-power synchronous motor excitation device according to claim 4 is characterized in that: The three-phase two-level PWM rectifiers of the three-phase PWM high-frequency rectifier all adopt dual-loop control, including a DC bus voltage control outer loop and an AC side input current control inner loop.

6. The high-power synchronous motor excitation device according to claim 1 is characterized in that: The input end of the staggered parallel bidirectional DC-DC converter (3) is connected to the DC bus, and the output end is connected to the excitation coil.

7. The high-power synchronous motor excitation device according to claim 6 is characterized in that: The capacity of the staggered parallel bidirectional DC-DC converter (3) is a 2-, 3- or 5-level bidirectional bridge circuit, and the number of parallel staggered H-bridge circuits is adjustable; the input end of the demagnetization circuit is connected to the DC bus.

8. The control method of the high-power synchronous motor excitation device according to any one of claims 1 to 7, characterized in that: The three-phase PWM high-frequency rectifier adopts a DC voltage outer loop control to provide the set DC bus voltage, and the more pulses the excitation transformer has, the higher the ripple frequency of the DC bus voltage and the smaller the fluctuation; the three-phase PWM high-frequency rectifier adopts a conventional grid-connected industrial frequency current control strategy to ensure that the AC side grid-connected current is sinusoidal and the power factor is adjustable; the three-phase PWM high-frequency rectifier also adds a machine-end additional damping controller to detect and calculate the modal compensation current of the low-frequency oscillation signal, and then injects it into the machine end of the synchronous motor through the current inner loop control of the three-phase PWM high-frequency rectifier, thereby providing a positive damping electromagnetic torque to suppress low-frequency oscillation; in addition, the current inner loop of the three-phase PWM high-frequency rectifier adopts current balancing measures, including master-slave current balancing or drooping current balancing, so as to realize that each parallel three-phase PWM high-frequency rectifier bears the transmission power on average to avoid overload of individual rectifiers.

9. The control method of the high-power synchronous motor excitation device according to any one of claims 1 to 7, characterized in that: The interleaved parallel bidirectional DC-DC converter (3) includes two operating conditions: excitation control and de-excitation control; Under the excitation control condition, the interleaved parallel bidirectional DC-DC converter (3) operates in a step-down mode, and uses an excitation voltage controller, including a PI controller, to quickly reduce the DC bus voltage to the required excitation voltage; the interleaved parallel bidirectional DC-DC converter (3) also adds an additional excitation damping controller to detect and calculate the modal compensation current of the low-frequency oscillation signal, and inject it into the excitation current of the synchronous motor, thereby providing a positive damping electromagnetic torque to suppress the low-frequency oscillation; In addition, the staggered parallel bidirectional DC-DC converter (3) adopts a current equalization measure in the voltage loop to achieve that each staggered parallel H bridge bears the transmission power evenly, thus avoiding overload of individual H bridge circuits; Under the demagnetization control condition, the interleaved parallel bidirectional DC-DC converter (3) operates in a boost mode, and uses a current controller, including a PI controller, to quickly release the stored electric energy in the excitation coil and inject it into the DC bus, causing the DC bus voltage to rise dynamically; the rise in the DC bus voltage will, on the one hand, trigger the three-phase PWM high-frequency rectifier to automatically feed back the excitation electric energy to the power grid, and on the other hand, when the DC bus voltage exceeds a preset threshold, the demagnetization resistor will be connected to the DC bus by closing the demagnetization switch, thereby consuming the excitation electric energy to accelerate the demagnetization speed of the excitation coil; Similarly, the interleaved parallel bidirectional DC-DC converter (3) adopts current balancing measures in the voltage loop to achieve that each interleaved parallel H bridge bears the transmission power evenly, thus avoiding overload of individual H bridge circuits; Similarly, the interleaved parallel bidirectional DC-DC converter (3) adopts current balancing measures to ensure that each interleaved parallel H-bridge bears the average transmission power, thereby avoiding overload of individual H-bridge circuits.

10. The control method of the high-power synchronous motor excitation device according to any one of claims 1 to 7, characterized in that: It also includes four three-phase PWM high-frequency rectifiers connected in parallel on the DC side electrically connected to a 24-pulse excitation transformer, as well as a multi-phase interleaved parallel bidirectional high-frequency DC-DC converter and a demagnetization circuit.

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