A marine multiphase high-speed permanent magnet DC generator controllable rectifier device with high short-circuit current resistance

Abstract

This invention discloses a controllable rectifier device for a marine multiphase high-speed permanent magnet DC generator with high short-circuit current tolerance. It includes several PWM combined rectifier modules, a PWM control unit, and a DC bus capacitor. Each PWM combined rectifier module consists of three SiC-MOSFET controllable rectifier bridge arms and three SCR controllable rectifier bridge arms connected in parallel. Each SiC-MOSFET controllable rectifier bridge arm is composed of two SiC-MOSFETs with anti-parallel diodes connected in series. The emitter of the upper SiC-MOSFET in the SiC-MOSFET controllable rectifier bridge arm is connected to the anode of the upper fast recovery thyristor in the SCR controllable rectifier bridge arm, and then connected to the generator's output terminal. Each PWM combined rectifier module is matched with a PWM control unit. This invention integrates DC voltage regulation, turning gear control, short-circuit protection, and device redundancy, effectively avoiding excessive system margin design, saving costs, and offering strong modular scalability.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically, to a controllable rectifier for a marine multiphase high-speed permanent magnet DC generator that can withstand large short-circuit currents. Background Technology

[0002] As a core component of various marine propulsion systems, generators can significantly reduce size and weight, increase power density, and improve the adaptability of generator sets by adopting high-speed direct-drive technology. If a multiphase electromagnetic scheme is also used, the system will have redundant reliability and exhibit more flexible adaptability.

[0003] Compared with multiphase electrically excited rectifier generators, multiphase high-speed permanent magnet rectifier generators have advantages such as high power density and high efficiency.

[0004] Due to the uncontrollable voltage and the need for generator turning gear, multiphase high-speed permanent magnet generators often use PWM controllable rectifier devices with bidirectional voltage flow and voltage regulation function at the back end.

[0005] The AC output voltage frequency of multiphase high-speed permanent magnet generators can typically reach 0.5k~1kHz. In order to reduce the output ripple of the PWM controllable rectifier, the carrier ratio design value (switching frequency / generator frequency) is generally not less than 10, that is, the switching frequency of the switching device is not less than 5kHz~10kHz, and SiC-MOSFET is generally selected.

[0006] While PWM controllable rectifiers can solve the problems of DC-side voltage regulation, stable output, and turning, permanent magnet generators have large transient and steady-state short-circuit currents when facing DC-side short circuits, which can easily damage switching devices. If the current rating of switching devices such as SiC-MOSFETs is selected based on the short-circuit current, it will result in an over-margin design of the system and higher costs. Fast thyristors are relatively cheaper than SiC-MOSFETs and have a stronger ability to withstand surge currents.

[0007] Among existing related patent technologies, such as the composite function converter for multiphase high-speed permanent magnet DC generators disclosed in patent document (CN120880212A), a BUCK control unit is used to achieve short-circuit current limiting protection. However, the control bandwidth of the two-stage architecture (rectifier + BUCK) is limited. When a short circuit occurs at the output of a high-speed permanent magnet generator (500~1000Hz), the rate of increase of the short-circuit current is extremely high. The outer loop limiting alone cannot complete the protection action within microseconds. The uncontrolled rectifier bridge arm uses high-frequency diodes in series, which cannot be actively turned off during a short circuit. The fault current still needs to be suppressed through the controllable bridge arm and the BUCK module. The use of high-frequency rectifier diodes, IGBTs, and SiC devices in combination requires separate adaptation of the drive circuit and heat dissipation design, which increases the complexity of the BOM and the engineering cost.

[0008] Therefore, there is an urgent need for a controllable rectifier for marine multiphase high-speed permanent magnet DC generators that can withstand large short-circuit currents. This rectifier should fully adapt to the short-circuit characteristics of multiphase high-speed permanent magnet generators and meet the requirements for DC power supply stability and safety. It should effectively avoid excessive system margin design, save costs, and have a simple and reliable structure with strong modular expandability. Summary of the Invention

[0009] The problem to be solved by this invention is to propose a controllable rectifier device for a marine multiphase high-speed permanent magnet DC generator that can withstand large short-circuit currents, in order to fully adapt to the requirements of short-circuit characteristics and DC power supply stability and safety of multiphase high-speed permanent magnet generators.

[0010] To achieve the above objectives, the technical solution of the present invention is: a controllable rectifier device for a marine multiphase high-speed permanent magnet DC generator with high short-circuit current tolerance, comprising several PWM combined rectifier modules, a PWM control unit, and a DC bus capacitor. The PWM combined rectifier module is composed of three SiC-MOSFET controllable rectifier bridge arms and three SCR controllable rectifier bridge arms connected in parallel. Each SiC-MOSFET controllable rectifier bridge arm is composed of two SiC-MOSFETs with anti-parallel diodes connected in series, designated as an upper SiC-MOSFET and a lower SiC-MOSFET. Each SCR controllable rectifier bridge arm is composed of two fast recovery thyristors with stronger inrush current tolerance connected in series, designated as an upper thyristor. The upper SIC-MOSFET of the SIC-MOSFET controllable rectifier bridge arm and the cathode of the upper fast recovery thyristor of the SCR controllable rectifier bridge arm are connected in parallel with the positive terminal of the DC bus capacitor; the emitter of the lower SIC-MOSFET of the SIC-MOSFET controllable rectifier bridge arm and the anode of the lower fast recovery thyristor of the SCR controllable rectifier bridge arm are connected in parallel with the negative terminal of the DC bus capacitor; the emitter of the upper SIC-MOSFET of the SIC-MOSFET controllable rectifier bridge arm and the anode of the upper fast recovery thyristor of the SCR controllable rectifier bridge arm are connected to the output terminal of the generator; each PWM combined rectifier module is matched with a PWM control unit.

[0011] Furthermore, the on-state voltage drop of the SiC-MOSFET is greater than that of the fast recovery thyristor.

[0012] Furthermore, if the number of PWM combined rectifier modules is A, the number of SiC-MOSFET controllable rectifier bridge arms is B, the number of SCR controllable rectifier bridge arms is C, and the number of generator phases is M, then the following conditions must be met simultaneously: 3A=B=C=M; B=C≥3; typically: take B=C=3.

[0013] Furthermore, each of the aforementioned PWM combined rectifier modules should be connected to the same set of three-phase windings with a phase difference of 120° at the generator output terminal.

[0014] Furthermore, the PWM control unit has three operating modes. The first operating mode controls the corresponding PWM combined rectifier module to operate in rectification mode, i.e., controlling the DC side output of a specified voltage, current, or power. In this mode, all fast recovery thyristors of the SCR controllable rectifier bridge arm are in the off state. The second operating mode controls the corresponding PWM combined rectifier module to operate in short-circuit protection mode, i.e., the SiC-MOSFETs of all SiC-MOSFET controllable rectifier bridge arms in the control module are disconnected, and all fast recovery thyristors of the SCR controllable rectifier bridge arms are turned off. When the thyristor is turned on, the short-circuit current is mainly borne by the fast recovery thyristor of the SCR controllable rectifier bridge arm, ensuring that the SiC-MOSFET is not damaged due to overcurrent. This operating mode is only activated when the DC side of the generator is short-circuited. The third operating mode is used to control the corresponding PWM combined rectifier module to operate in a turning mode, that is, switching from rectification to inverter output variable voltage variable frequency AC power to drive the generator to run at low speed in electric mode. At this time, all fast recovery thyristors of the SCR controllable rectifier bridge arm are in the off state. This operating mode is only activated when the generator system shaft needs to be turned.

[0015] Furthermore, when the power of a single PWM combined rectifier module is insufficient to meet the system requirements, multiple PWM combined rectifier modules are connected in series and parallel.

[0016] Furthermore, when multiple PWM combined rectifier modules are connected in series and parallel, the PWM control units of each PWM combined rectifier module form a master-slave structure through a communication network.

[0017] Furthermore, when the PWM control unit operates in rectification mode, the master unit has a dual closed-loop control structure, while the slave unit has a single closed-loop control structure. The master unit responds to the system's voltage regulation operation command, while the slave unit only responds to the master unit's control command. The master unit has an outer voltage loop and an inner current loop, while the slave unit only has an inner current loop.

[0018] The dual-loop control structure has an outer loop input that is the difference between the DC voltage given by the system and the actual DC voltage output, and an output that is the current value given to each module. The inner loop input is the difference between the current value given to each module by the outer loop output and the actual current value output by this module, and an output that is the PWM duty cycle of the controllable rectifier bridge arm of this module. The single-loop control structure has an input that is the difference between the current value given to each module by the host and the actual current value output by this module, and an output that is the PWM duty cycle of the controllable rectifier bridge arm of this module.

[0019] Furthermore, when the PWM control unit operates in short-circuit protection mode, that is, when a DC-side short-circuit signal is detected, the host responds to the system's instruction to turn off the SiC-MOSFETs of each module and turn on the fast recovery thyristors of each module. The slave responds to the host's control instruction and outputs that the PWM duty cycle of the SiC-MOSFET controllable rectifier bridge arm of this module is 0, while simultaneously turning on the conduction signal of the SCR controllable rectifier bridge arm of this module.

[0020] The beneficial effects of this invention are:

[0021] This invention provides a controllable rectifier for a marine multiphase high-speed permanent magnet DC generator capable of withstanding large short-circuit currents. It integrates DC voltage regulation, turning gear control, short-circuit protection, and device redundancy, effectively avoiding excessive system margin design and saving costs. Furthermore, it features a simple and reliable structure with strong modular expandability. When a short circuit occurs on the DC side of the generator, a fast recovery thyristor with stronger inrush current tolerance bears the short-circuit current, preventing the SiC-MOSFET from breaking down due to overcurrent. If the freewheeling diode inside the SiC-MOSFET fails, the fast recovery thyristor, in a conducting state, can temporarily assume the freewheeling function, ensuring normal system operation. This provides a feasible solution to the problems of DC power supply voltage regulation, stable output, short-circuit protection, and high cost associated with multiphase high-speed permanent magnet DC generator applications. Attached Figure Description

[0022] Figure 1 It is the marine multiphase high-speed permanent magnet DC generator controllable rectifier device with high short-circuit current in the embodiment. Figure 2 This is the master-slave controller structure in the embodiment. Detailed Implementation Plan To make the objectives, technical solutions, and advantages of the present invention clearer, the following description, through embodiments and accompanying drawings, provides a more detailed explanation. It should be noted that the embodiments described below are merely for illustrative purposes and are not intended to limit the scope of the invention.

[0023] In the following embodiments, for ease of description, we will take the adaptation of a twelve-phase permanent magnet high-speed generator as an example and use four sets of PWM combined rectifier modules as a typical case for explanation. Obviously, the adjustments made to the number of generator phases and the number of PWM combined rectifier modules are still within the scope of this invention.

[0024] like Figure 1 As shown in the figure, a controllable rectifier device suitable for multiphase high-speed permanent magnet DC generator provided by an embodiment of the present invention includes four sets of PWM combined rectifier modules (including twelve sets of SiC-MOSFET controllable rectifier bridge arms and twelve sets of SCR controllable rectifier bridge arms), four sets of PWM control units, and DC bus capacitors.

[0025] The bridge arm consists of twelve SiC-MOSFET controllable rectifier arms, each consisting of two SiC-MOSFETs with anti-parallel diodes, and is divided into upper SiC-MOSFET and lower SiC-MOSFET. The twelve SCR controllable rectifier bridge arms are composed of two fast recovery thyristors, namely the upper fast recovery thyristor and the lower fast recovery thyristor. The on-state voltage drop of a SiC-MOSFET is greater than that of a fast recovery thyristor.

[0026] The collector of the upper SIC-MOSFET in the SIC-MOSFET controlled rectifier bridge arm and the cathode of the upper fast recovery thyristor in the SCR controlled rectifier bridge arm are connected in parallel with the positive terminal of the DC bus capacitor.

[0027] The emitter of the lower SIC-MOSFET in the SIC-MOSFET controlled rectifier bridge arm and the anode of the lower fast recovery thyristor in the SCR controlled rectifier bridge arm are connected in parallel with the negative terminal of the DC bus capacitor.

[0028] The emitter of the upper SIC-MOSFET (i.e. the collector of the lower SIC-MOSFET) of the SIC-MOSFET controllable rectifier bridge arm is connected to the anode of the upper fast recovery thyristor (i.e. the cathode of the lower fast recovery thyristor) of the SCR controllable rectifier bridge arm and then connected to the output terminal of the generator; wherein, a single PWM combined rectifier module should be connected to the same three-phase winding with a phase difference of 120° at the output terminal of the generator.

[0029] The four PWM control units, namely PWM control unit 1 to PWM control unit 4, are used to control the four parallel PWM combined rectifier modules, namely PWM combined rectifier module 1 to PWM combined rectifier module 4.

[0030] The PWM control unit 1 has three operating modes. The first operating mode controls the corresponding PWM combined rectifier module to operate in rectification mode, i.e., controlling the DC side output of a specified voltage, current, or power. In this mode, all fast recovery thyristors of the SCR controllable rectifier bridge arm are in the off state. The second operating mode controls the corresponding PWM combined rectifier module to operate in short-circuit protection mode, i.e., all SiC-MOSFETs of the controllable rectifier bridge arm in the control module are disconnected, and all fast recovery thyristors of the SCR controllable rectifier bridge arm are turned on. In this mode, the short-circuit current is mainly borne by the fast recovery thyristors of the SCR controllable rectifier bridge arm. This operating mode is only activated when the generator DC side is short-circuited. The third operating mode controls the corresponding PWM combined rectifier module to operate in turning mode, i.e., switching from rectification to inverter output of variable voltage and variable frequency AC power to drive the generator to operate at low speed in electric mode. In this mode, all fast recovery thyristors of the SCR controllable rectifier bridge arm are in the off state. This operating mode is only activated when the generator system shaft needs to be turned.

[0031] PWM control units 2 to 4 have only two operating modes: rectification mode and short-circuit protection mode.

[0032] To address the coordinated control issue of multiple PWM control units operating in rectification mode and short-circuit protection mode when multiple modules are connected in series and parallel, this invention also provides a control method for multiple modules connected in series and parallel. This control method involves the PWM control units of each module forming a master-slave structure through a communication network, as described above. Figure 2 .

[0033] When the PWM control unit operates in rectification mode, the master unit has a dual-closed-loop control structure, while the slave unit has a single-closed-loop control structure. The master unit responds to the system's voltage regulation operation commands, while the slave unit only responds to the master unit's control commands. The master unit has an outer voltage loop and an inner current loop, while the slave unit only has an inner current loop.

[0034] The host computer features a dual closed-loop structure. The outer loop input is the difference between the system-given DC voltage and the actual output DC voltage, and the output is the given current value for each module. The inner loop input is the difference between the given current value for each module output from the outer loop and the actual output current value of this module, and the output is the PWM duty cycle of the controllable rectifier bridge arm of this module.

[0035] The slave-based single-closed-loop structure has an input that is the difference between the current value of each module given by the host and the actual current value output by this module, and an output that is the PWM duty cycle of the controllable rectifier bridge arm of this module.

[0036] When the PWM control unit operates in short-circuit protection mode, that is, when a short-circuit signal is detected, the host responds to the system's instruction to turn off the SiC-MOSFETs of each module and turn on the fast recovery thyristors of each module. The slave responds to the host's control instruction and outputs that the PWM duty cycle of the controllable rectifier bridge arm of this module is 0, and at the same time turns on the conduction signal of the controllable rectifier bridge arm of this module.

[0037] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the invention is not limited thereto. Any improvements made by those skilled in the art within the scope of the technical solution disclosed in the present invention, without changing the principle, should also be considered within the scope of protection of the present invention.

Claims

1. A controllable rectifier device for a marine multiphase high-speed permanent-magnet DC generator with high short-circuit current resistance, characterized in that: It includes several PWM combined rectifier modules, a PWM control unit, and a DC bus capacitor. The PWM combined rectifier modules consist of three SiC-MOSFET controllable rectifier bridge arms and three SCR controllable rectifier bridge arms connected in parallel. Each SiC-MOSFET controllable rectifier bridge arm is composed of two SiC-MOSFETs with anti-parallel diodes connected in series, designated as an upper SiC-MOSFET and a lower SiC-MOSFET. Each SCR controllable rectifier bridge arm is composed of two fast recovery thyristors with stronger inrush current tolerance connected in series, designated as an upper thyristor and a lower thyristor. The SiC-MOSFET controllable rectifier bridge... The collector of the upper SiC-MOSFET of the SCR controllable rectifier bridge arm, the cathode of the upper fast recovery thyristor of the SCR controllable rectifier bridge arm, and the positive terminal of the DC bus capacitor are connected in parallel; the emitter of the lower SiC-MOSFET of the SCR controllable rectifier bridge arm, the anode of the lower fast recovery thyristor of the SCR controllable rectifier bridge arm, and the negative terminal of the DC bus capacitor are connected in parallel; the emitter of the upper SiC-MOSFET of the SCR controllable rectifier bridge arm and the anode of the upper fast recovery thyristor of the SCR controllable rectifier bridge arm are connected to the output terminal of the generator; each of the PWM combined rectifier modules is matched with a PWM control unit.

2. The multi-phase high speed permanent magnet DC generator controllable rectifier for marine use with high short circuit current tolerance according to claim 1, characterized in that: The on-state voltage drop of the SiC-MOSFET is greater than that of the fast recovery thyristor.

3. The multi-phase high speed permanent magnet DC generator controllable rectifier for marine use with high short circuit current tolerance according to claim 1, characterized in that: If the number of PWM combined rectifier modules is A, the number of SiC-MOSFET controllable rectifier bridge arms is B, the number of SCR controllable rectifier bridge arms is C, and the number of generator phases is M, then the following conditions are simultaneously satisfied: 3A=B=C=M; B=C≥3; Typically: take B=C=3.

4. The multi-phase high speed permanent magnet DC generator controllable rectifier for marine use with high short circuit current tolerance according to claim 1, characterized in that: Each of the aforementioned PWM combined rectifier modules is connected to the same set of three-phase windings at the generator output terminal, with a phase difference of 120°.

5. The multi-phase high speed permanent magnet DC generator controllable rectifier for marine use with high short circuit current tolerance according to claim 1, characterized in that: The PWM control unit has three operating modes. The first operating mode controls the corresponding PWM combined rectifier module to operate in rectification mode, i.e., controlling the DC side output of a specified voltage, current, or power. In this mode, all fast recovery thyristors of the SCR controllable rectifier bridge arm are in the off state. The second operating mode controls the corresponding PWM combined rectifier module to operate in short-circuit protection mode, i.e., the SiC-MOSFETs of all SiC-MOSFET controllable rectifier bridge arms in the control module are disconnected, and all fast recovery thyristors of the SCR controllable rectifier bridge arms are turned on. In this mode, the short-circuit current is mainly borne by the fast recovery thyristors of the SCR controllable rectifier bridge arms, ensuring that the SiC-MOSFETs are not damaged due to overcurrent. This operating mode is only activated when the generator DC side is short-circuited. The third operating mode controls the corresponding PWM combined rectifier module to operate in turning mode, i.e., switching from rectification to inverter output of variable voltage and variable frequency AC power to drive the generator to operate at low speed in electric mode. In this mode, all fast recovery thyristors of the SCR controllable rectifier bridge arm are in the off state. This operating mode is only activated when the generator system shaft needs to be turned.

6. The multi-phase high speed permanent magnet DC generator controllable rectifier for marine use with high short circuit current tolerance according to claim 1, characterized in that: When the power of a single PWM combined rectifier module is insufficient to meet the system requirements, multiple PWM combined rectifier modules are connected in series and parallel.

7. The controllable rectifier device for a marine multiphase high-speed permanent magnet DC generator with high short-circuit current tolerance as described in claim 6, characterized in that: When multiple PWM combined rectifier modules are connected in series and parallel, the PWM control units of each PWM combined rectifier module form a master-slave structure through a communication network.

8. The controllable rectifier device for a marine multiphase high-speed permanent magnet DC generator with high short-circuit current tolerance as described in claim 7, characterized in that: When the PWM control unit operates in rectification mode, the master unit has a dual closed-loop control structure, and the slave unit has a single closed-loop control structure. The master unit responds to the system's voltage regulation operation command, while the slave unit only responds to the master unit's control command. The master unit has an outer voltage loop and an inner current loop, while the slave unit only has an inner current loop.

9. The controllable rectifier device for a marine multiphase high-speed permanent magnet DC generator with high short-circuit current tolerance as described in claim 8, characterized in that: The dual-loop control structure has an outer loop input that is the difference between the DC voltage given by the system and the actual DC voltage output, and an output that is the current value given to each module. The inner loop input is the difference between the current value given to each module by the outer loop output and the actual current value output by this module, and an output that is the PWM duty cycle of the controllable rectifier bridge arm of this module. The single-loop control structure has an input that is the difference between the current value given to each module by the host and the actual current value output by this module, and an output that is the PWM duty cycle of the controllable rectifier bridge arm of this module.

10. The controllable rectifier device for a marine multiphase high-speed permanent magnet DC generator with high short-circuit current tolerance as described in claim 9, characterized in that: When the PWM control unit operates in short-circuit protection mode, that is, when a DC-side short-circuit signal is detected, the host responds to the system's instruction to turn off the SiC-MOSFETs of each module and turn on the fast recovery thyristors of each module. The slave responds to the host's control instruction and outputs that the PWM duty cycle of the SiC-MOSFET controllable rectifier bridge arm of this module is 0, while simultaneously turning on the conduction signal of the SCR controllable rectifier bridge arm of this module.

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