Composite function converter suitable for multi-phase high-speed permanent magnet direct-current generator

Abstract

The invention relates to a composite function converter suitable for a multi-phase high-speed permanent magnet direct-current generator. An uncontrolled rectifier bridge arm is formed by connecting two high-frequency rectifier diodes in series; the controllable rectifier bridge arm is formed by connecting two IGBTs (Insulated Gate Bipolar Translator) with antiparallel diodes in series; an upper tube IGBT collector of the controllable rectifier bridge arm and a cathode of an upper tube diode of the uncontrolled rectifier bridge arm are connected in parallel with an anode of the intermediate bus capacitor; the emitting electrode of the lower tube IGBT and the anode of the lower tube diode of the uncontrolled rectifier bridge arm are connected in parallel with the cathode of the intermediate bus capacitor; the emitting electrodes of the upper tubes IGBT of the controllable rectifier bridge arms are respectively connected to the output end of the generator; the anodes of the upper diodes of the uncontrolled rectifier bridge arms are respectively connected to the other output ends of the generator; the interleaved BUCK module is connected between the intermediate DC bus capacitor and the load, and the BUCK control unit is used for controlling the interleaved BUCK module to operate; and the barring control unit is used for controlling the controllable rectifier bridge arm to realize a generator barring function.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, specifically to a composite function converter suitable for multiphase high-speed permanent magnet DC generators, especially suitable for scenarios with limited installation space, direct drive of high-speed prime movers, and high requirements for power supply stability and safety. Background Technology

[0002] High-speed permanent magnet generators offer significant advantages in applications with specific requirements, such as limited installation space and direct drive from a high-speed prime mover, due to their high power density, compact structure, and lack of an excitation system. Furthermore, employing a multiphase electromagnetic scheme provides redundancy and reliability, exhibiting greater flexibility in adaptability.

[0003] However, since permanent magnet generators do not have active excitation voltage regulation capability and have relatively soft load characteristics, if only an uncontrolled rectification scheme is used, the DC output voltage of the system will fluctuate within a large range as the load changes, making it difficult to meet the power supply stability requirements.

[0004] While existing technologies like PWM controllable rectification can solve the problems of DC-side voltage regulation and stabilization, the carrier frequency must be increased to adapt to the high-frequency (typically 500–1000 Hz) AC output voltage of multiphase high-speed permanent magnet generators. However, the high-frequency harmonic currents brought about by the high carrier frequency will pose challenges to the motor's thermal and insulation design. In addition, the need to solve the problem of multiphase coordinated control makes the system complex. Furthermore, PWM controllable rectification technology itself does not have DC-side output current limiting and protection functions, posing a significant operational risk when the load side is short-circuited.

[0005] Among existing related patents, such as the multiphase high-power generator-converter integrated system disclosed in patent document (CN106451531B), the sub-modules of its modular multilevel inverter include three-phase PWM rectifiers, resulting in a complex structure, prominent harmonic problems at high frequencies, and the lack of dedicated current-limiting protection and turning gear function, making it unsuitable for high-speed scenarios. The permanent magnet synchronous motor converter device based on the MMC structure disclosed in patent document (CN204696934U) uses a chain-type series structure of fully controlled devices, which improves the voltage level, but the high carrier frequency leads to large harmonics in high-frequency applications, and the lack of integrated turning gear control and current-limiting protection makes it insufficiently adaptable to multiphase high-speed generators. Summary of the Invention

[0006] The problem to be solved by this invention is to propose a composite function converter suitable for multiphase high-speed permanent magnet DC generators in order to fully adapt to the characteristics of multiphase high-speed permanent magnet generators and the requirements for DC power supply stability and safety, in view of the above-mentioned situation.

[0007] To achieve the above objectives, the technical solution of the present invention is: a composite function converter suitable for multiphase high-speed permanent magnet DC generators, comprising several uncontrolled rectifier bridge arms, controlled rectifier bridge arms, an intermediate DC bus capacitor, interleaved parallel BUCK modules, a BUCK control unit, and a turning gear control unit; the uncontrolled rectifier bridge arms are composed of two high-frequency rectifier diodes connected in series; the controlled rectifier bridge arms are composed of two IGBTs with anti-parallel diodes connected in series; the collector of the upper IGBT of the controlled rectifier bridge arm, the cathode of the upper diode of the uncontrolled rectifier bridge arm, and the positive terminal of the intermediate bus capacitor are connected in parallel; the emitter of the lower IGBT of the controlled rectifier bridge arm... The anode of the lower diode of the uncontrolled rectifier bridge arm is connected in parallel with the cathode of the intermediate bus capacitor; the emitter of the upper IGBT of the controlled rectifier bridge arm, i.e., the collector of the lower IGBT, is connected to the output terminal of the generator; the anode of the upper diode of the uncontrolled rectifier bridge arm, i.e., the cathode of the lower diode, is connected to the remaining output terminals of the generator; the interleaved parallel BUCK module is connected between the intermediate DC bus capacitor and the load; the BUCK control unit is used to control the operation of the interleaved parallel BUCK module, including controlling the DC side output of a specified voltage, current, or power; the turning control unit is used to control the controlled rectifier bridge arm to realize the generator turning function.

[0008] Furthermore, let A be the number of uncontrolled rectifier bridge arms, B be the number of controlled rectifier bridge arms, and M be the number of generator phases, satisfying the condition: A+B=M and B≥3; wherein B=3, and the 3 sets of controlled rectifier bridge arms are respectively connected to the same set of three-phase windings with a phase difference of 120° at the generator output terminal.

[0009] Furthermore, the interleaved parallel BUCK module includes several SiC-MOSFET bridge arms, a filter inductor, and a filter capacitor. Each SiC-MOSFET bridge arm is formed by two SiC-MOSFETs connected in series with anti-parallel SiC diodes. The drain of the upper SiC-MOSFET is connected to the positive terminal of the intermediate bus capacitor, and the source of the lower SiC-MOSFET is connected to the negative terminal of the intermediate bus capacitor. The source of the upper SiC-MOSFET, which is also the drain of the lower SiC-MOSFET, is connected to the input terminal of the filter inductor. The output terminal of the filter inductor is connected in parallel to the positive terminal of the output filter capacitor. The negative terminal of the output filter capacitor is connected in parallel to the negative terminal of the intermediate bus capacitor.

[0010] Furthermore, the interleaved parallel BUCK module is a two-phase interleaved parallel BUCK module, including two sets of SiC-MOSFET bridge arms, two filter inductors, and one set of output filter capacitors; or the interleaved parallel BUCK module is a three-phase interleaved BUCK module, including three sets of SiC-MOSFET bridge arms, three filter inductors, and one set of output filter capacitors.

[0011] Furthermore, the turning control unit controls the controllable rectifier bridge arm, which is activated only when the generator system shaft needs to be turned, and the inverter outputs variable voltage and variable frequency AC power to drive the generator to operate at low speed in electric mode.

[0012] Furthermore, each interleaved parallel BUCK module is matched with a BUCK control unit. When the power of a single module is insufficient to meet the system requirements, multiple interleaved parallel BUCK modules operate in parallel.

[0013] Furthermore, when multiple interleaved parallel BUCK modules are connected, the BUCK control units of each interleaved parallel BUCK module form a master-slave structure through a communication network. The master is a dual closed-loop control structure, and the slave is a single closed-loop control structure. The master responds to the system's voltage regulation operation command, while the slave only responds to the master's control command. The master's outer loop is a voltage loop, and its inner loop is a current loop, while the slave only has an inner current loop.

[0014] Furthermore, the host dual closed-loop 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 output by the outer loop and the actual current value output by this module, and an output that is the PWM duty cycle of each branch of this module in alternating parallel connection.

[0015] Furthermore, in the slave single closed-loop structure, the input is the difference between the current value of each module given by the host and the actual output current value of this module, and the output is the PWM duty cycle of each branch of this module in alternating parallel connection.

[0016] Furthermore, the BUCK control unit performs amplitude limiting processing on the outer loop output of the converter to achieve current limiting protection under output short-circuit conditions.

[0017] The beneficial effects of this invention are:

[0018] 1. Stable voltage and low harmonics: The uncontrolled rectifier bridge arm is the main regulator, and the controlled rectifier bridge arm is the auxiliary regulator, which reduces the harmonics caused by high-frequency PWM control. At the same time, DC output voltage is regulated by interleaved parallel BUCK modules.

[0019] 2. Multifunctional: It integrates turning gear control (no additional device required), DC voltage regulation, and current limiting protection functions, simplifying the system structure.

[0020] 3. High safety: Through the limiting processing of the BUCK control unit, current limiting protection is achieved under operating conditions such as output short circuit, reducing operational risks.

[0021] 4. High scalability: The modular design supports the parallel operation of multiple interleaved BUCK modules to adapt to different power requirements.

[0022] In summary, the composite-function converter for multiphase high-speed permanent magnet DC generators provided by this invention integrates functions such as turning gear control, DC voltage regulation, and current limiting protection. During normal operation, there is no high-frequency harmonic injection on the generator side. It features a simple and reliable structure and strong modular expandability. This invention provides a feasible solution to the problems of DC power supply voltage regulation, stable output, current limiting protection, and harmonic reduction on the generator side that arise in the application of multiphase high-speed permanent magnet DC generators. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the composite function converter structure applicable to multiphase high-speed permanent magnet DC generators of the present invention;

[0024] Figure 2 This is a schematic diagram of a master-slave controller structure. Detailed Implementation

[0025] 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.

[0026] In the following embodiments, for ease of description, a 12-phase permanent magnet high-speed generator is used as an example, and four sets of three-phase interleaved parallel BUCK modules are used as a typical case for explanation. Obviously, the adjustments made to the number of generator phases, the number of interleaved parallel phases, and the number of BUCK module groups are still within the scope of this invention.

[0027] like Figure 1 The diagram shows the structural composition of a composite function converter for multiphase high-speed permanent magnet DC generators according to an embodiment of the present invention; it includes 9 sets of uncontrolled rectifier bridge arms, 3 sets of controllable rectifier bridge arms, an intermediate DC bus capacitor, three sets of three-phase interleaved parallel BUCK modules, three BUCK control units, and one turning gear control unit.

[0028] The generator consists of 9 uncontrolled rectifier bridge arms, each composed of two high-frequency rectifier diodes connected in series; and 3 controlled rectifier bridge arms, each composed of two IGBTs with anti-parallel diodes. The collector of the upper IGBT in the controlled rectifier bridge arm, the cathode of the upper diode in the uncontrolled rectifier bridge arm, and the positive terminal of the intermediate bus capacitor are connected in parallel. The emitter of the lower IGBT in the controlled rectifier bridge arm, and the anode of the lower diode in the uncontrolled rectifier bridge arm, and the negative terminal of the intermediate bus capacitor are connected in parallel. The emitter (i.e., the collector of the lower IGBT) of the upper IGBT in the controlled rectifier bridge arm is connected to the output terminals of a set of three-phase windings with a 120° phase difference from each other. The anode (i.e., the cathode of the lower diode) of the upper diode in the uncontrolled rectifier bridge arm is connected to the remaining output terminals of the generator.

[0029] Three sets of three-phase interleaved parallel BUCK modules, each set including three SiC-MOSFET bridge arms, three filter inductors, and one output filter capacitor; the SiC-MOSFET bridge arms are composed of two SiC-MOSFETs connected in series with anti-parallel SiC diodes; the drain of the upper SiC-MOSFET is connected to the positive terminal of the intermediate bus capacitor, and the source of the lower SiC-MOSFET is connected to the negative terminal of the intermediate bus capacitor; the source of the upper SiC-MOSFET (i.e., the drain of the lower SiC-MOSFET) is connected to the input terminal of the filter inductor; the output terminal of the filter inductor is connected in parallel to the positive terminal of the output filter capacitor; the negative terminal of the output filter capacitor is connected in parallel to the negative terminal of the intermediate bus capacitor.

[0030] Three BUCK control units are used to control three sets of interleaved parallel BUCK modules, controlling the DC side output of specified voltage, current or power.

[0031] The turning control unit is used to control three sets of controllable rectifier bridge arms. It is activated only when the generator system shaft needs to be turned. The inverter outputs variable voltage and variable frequency AC power to drive the generator to run at low speed in electric mode.

[0032] To address the issue of coordinated control of the various BUCK control units in three sets of three-phase interleaved parallel BUCK modules, this invention also provides a control method for multiple modules in parallel.

[0033] like Figure 2 As shown, the control method is characterized by the following: the BUCK control units of each module form a master-slave structure through a communication network. 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 voltage signal given by the system, while the slave unit only responds to the current signal given by the master unit; the outer loop of the master unit is a voltage loop, and the inner loop is a current loop, while the slave unit only has an inner current loop.

[0034] The host has a dual closed-loop structure. The outer loop input is the difference between the DC voltage given by the system and the actual DC voltage output, and the output 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 the output is the PWM duty cycle of each branch of this module in alternating parallel connection.

[0035] The slave-based single-closed-loop control 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 each branch of this module in alternating parallel connection.

[0036] To address the current limiting protection issue under conditions such as output short circuit, the output of the converter's outer loop is subjected to amplitude limiting.

[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 composite function converter suitable for multiphase high-speed permanent magnet DC generators, characterized in that, It includes several uncontrolled rectifier bridge arms, controlled rectifier bridge arms, an intermediate DC bus capacitor, interleaved parallel BUCK modules, a BUCK control unit, and a turning gear control unit; each uncontrolled rectifier bridge arm is composed of two high-frequency rectifier diodes connected in series; each controlled rectifier bridge arm is composed of two IGBTs with anti-parallel diodes connected in series; the collector of the upper IGBT of the controlled rectifier bridge arm, the cathode of the upper diode of the uncontrolled rectifier bridge arm, and the anode of the intermediate bus capacitor are connected in parallel; the emitter of the lower IGBT of the controlled rectifier bridge arm, the anode of the lower diode of the uncontrolled rectifier bridge arm, and the intermediate bus capacitor are connected in parallel. The negative terminals of the capacitors are connected in parallel; the emitter of the upper IGBT of the controllable rectifier bridge arm, i.e., the collector of the lower IGBT, is connected to the output terminal of the generator; the anode of the upper diode of the uncontrolled rectifier bridge arm, i.e., the cathode of the lower diode, is connected to the remaining output terminals of the generator; the interleaved parallel BUCK module is connected between the intermediate DC bus capacitor and the load; the BUCK control unit is used to control the operation of the interleaved parallel BUCK module, including controlling the DC side output of a specified voltage, current, or power; the turning control unit is used to control the controllable rectifier bridge arm to realize the generator turning function.

2. The composite function converter for multiphase high-speed permanent magnet DC generators according to claim 1, characterized in that, Let A be the number of uncontrolled rectifier bridge arms, B be the number of controlled rectifier bridge arms, and M be the number of generator phases, satisfying the conditions: A+B=M and B≥3; wherein B=3, and the 3 sets of controlled rectifier bridge arms are respectively connected to the same set of three-phase windings with a phase difference of 120° at the generator output terminal.

3. The composite function converter for multiphase high-speed permanent magnet DC generators according to claim 1, characterized in that, The interleaved parallel BUCK module includes several SiC-MOSFET bridge arms, a filter inductor, and a filter capacitor. Each SiC-MOSFET bridge arm is formed by two SiC-MOSFETs connected in series with anti-parallel SiC diodes. The drain of the upper SiC-MOSFET is connected to the positive terminal of the intermediate bus capacitor, and the source of the lower SiC-MOSFET is connected to the negative terminal of the intermediate bus capacitor. The source of the upper SiC-MOSFET, which is also the drain of the lower SiC-MOSFET, is connected to the input terminal of the filter inductor. The output terminal of the filter inductor is connected in parallel to the positive terminal of the output filter capacitor. The negative terminal of the output filter capacitor is connected in parallel to the negative terminal of the intermediate bus capacitor.

4. The composite function converter for multiphase high-speed permanent magnet DC generators according to claim 3, characterized in that, The interleaved parallel BUCK module is a two-phase interleaved parallel BUCK module, including two sets of SiC-MOSFET bridge arms, two filter inductors, and one set of output filter capacitors; or the interleaved parallel BUCK module is a three-phase interleaved BUCK module, including three sets of SiC-MOSFET bridge arms, three filter inductors, and one set of output filter capacitors.

5. The composite function converter for multiphase high-speed permanent magnet DC generators according to claim 1, characterized in that, The turning control unit controls the controllable rectifier bridge arm, which is activated only when the generator system shaft needs to be turned. The inverter outputs variable voltage and variable frequency AC power to drive the generator to operate at low speed in electric mode.

6. The composite function converter for multiphase high-speed permanent magnet DC generators according to claim 1, characterized in that, Each interleaved parallel BUCK module is matched with a BUCK control unit. When the power of a single module is insufficient to meet the system requirements, multiple interleaved parallel BUCK modules operate in parallel.

7. The composite function converter for multiphase high-speed permanent magnet DC generators according to claim 6, characterized in that, When multiple interleaved parallel BUCK modules are connected, the BUCK control units of each interleaved parallel BUCK module form a master-slave structure through a communication network. The master is a dual closed-loop control structure, and the slave is a single closed-loop control structure. The master responds to the system's voltage regulation operation command, while the slave only responds to the master's control command. The master's outer loop is a voltage loop and its inner loop is a current loop, while the slave only has an inner current loop.

8. The composite function converter for multiphase high-speed permanent magnet DC generators according to claim 7, characterized in that, The host has a dual closed-loop structure. The outer loop input is the difference between the DC voltage given by the system and the actual DC voltage output, and the output is the current value given to each module. The inner loop input is the difference between the current value given to each module output by the outer loop and the actual current value output by this module, and the output is the PWM duty cycle of each branch of this module in alternating parallel connection.

9. The composite function converter for multiphase high-speed permanent magnet DC generators according to claim 7, characterized in that, The slave single closed-loop structure takes as input the difference between the current value of each module given by the master and the actual current value output by this module, and outputs the PWM duty cycle of each branch of this module in alternating parallel connection.

10. The composite function converter for multiphase high-speed permanent magnet DC generators according to claim 1, characterized in that, The BUCK control unit performs amplitude limiting processing on the outer loop output of the converter to achieve current limiting protection under output short-circuit conditions.

Images