A multi-module parallel synchronous control method for high-power converters

Abstract

The present invention provides a multi-module parallel synchronous control method for a high-power converter, comprising: a centralized control subsystem calculating and outputting a q-axis current setpoint, a d-axis current setpoint, and a phase angle for controlling each submodule based on motor voltage and motor current, and distributing the q-axis current setpoint, d-axis current setpoint, and phase angle to each submodule control system; and each submodule control system calculating and outputting a control duty cycle for controlling each submodule based on the q-axis current setpoint, d-axis current setpoint, and phase angle, and controlling the corresponding submodule based on the control duty cycle. The present invention outputs power device control signals for each submodule based on the collected voltage and current at the submodule output end and the motor voltage and current through a dual closed-loop control algorithm, thereby achieving variable-frequency speed control of the motor load. This method can effectively reduce parallel circulating currents, balance submodule currents, and improve the output power quality of the inverter.

Description

Technical Field

[0001] The present invention relates to the field of frequency converter control, and more particularly to a multi-module parallel synchronous control method for a high-power converter. Background Art

[0002] Multi-module paralleling is a key technology for increasing inverter power levels. High-power inverters can be achieved by connecting multiple low-power modules in parallel. However, since the modules cannot be completely electrically and structurally identical when connected in parallel, problems such as circulating current and current imbalance can occur between modules, affecting the inverter's output power quality. Summary of the Invention

[0003] The present invention provides a multi-module parallel synchronous control method for a high-power converter in order to reduce parallel circulating current, balance submodule currents, and improve the quality of power output by the converter.

[0004] The present invention provides a multi-module parallel synchronous control method for a high-power converter, comprising:

[0005] Based on the motor voltage and motor current, the centralized control subsystem calculates and outputs the q-axis current set value, d-axis current set value, and phase angle for each submodule, and sends the q-axis current set value, d-axis current set value, and phase angle to each submodule control system;

[0006] According to the q-axis current given value, the d-axis current given value and the phase angle, each submodule control system calculates and outputs a control duty cycle for controlling each submodule, and controls the corresponding submodule based on the control duty cycle.

[0007] The present invention provides a multi-module parallel synchronous control method for high-power converters. Based on the collected voltage and current at the output ends of the sub-modules and the motor voltage and current, a dual closed-loop control algorithm is used to output power device control signals for each sub-module, thereby realizing variable frequency speed control of the motor load. This method can effectively reduce parallel circulating current, balance the sub-module current, and improve the output power quality of the inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A flow chart of a multi-module parallel synchronous control method for a high-power converter provided by an embodiment of the present invention;

[0009] Figure 2 A schematic diagram of a multi-module parallel synchronous control system for a high-power converter provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention can be arbitrarily combined with each other to form a feasible technical solution. This combination is not restricted by the sequence of steps and / or structural composition mode, but must be based on the ability of ordinary technicians in this field to implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0011] See also Figure 1 , provides a flow chart of a multi-module parallel synchronous control method for a high-power converter according to an embodiment of the present invention. The control method is based on Figure 2 The multi-module parallel synchronous control system shown is controlled, wherein, Figure 2 The number of submodule control systems in the embodiment is four, which is only one embodiment of the present invention. In practice, a larger number of submodule control systems may be used in the control system, which should not limit the present invention.

[0012] Figure 2 In the system, the multi-module parallel synchronous control system includes a centralized control system and multiple sub-module control systems, and each system shares one CAN bus and two RS485 buses.

[0013] An embodiment of the present invention provides a multi-module parallel synchronous control method for a high-power converter, comprising the following steps:

[0014] Step 1: Based on the motor voltage and motor current, the centralized control subsystem calculates the q-axis current set value, d-axis current set value and phase angle of each submodule for output control, and sends the q-axis current set value, d-axis current set value and phase angle to each submodule control system.

[0015] Among them, motors can be mainly divided into permanent magnet synchronous motors and asynchronous motors. When the motor types are different, the centralized control system has different methods for calculating the q-axis current set value, the d-axis current set value and the phase angle.

[0016] In a possible embodiment of the present invention, when the motor is a permanent magnet synchronous motor, the centralized control system uses an outer loop closed-loop control algorithm to calculate and output a q-axis current set value, a d-axis current set value, and a phase angle for each submodule based on the motor voltage and motor current, including:

[0017] Step 11, according to the current moment Axis estimated current and current moment Estimated axis current and the motor current at the current moment The actual current of the shaft and the motor at the current moment The actual current of the axis is calculated at the current moment. The proportional integral output of the axis disturbance loop and the current moment Shaft disturbance loop proportional integral output.

[0018] In one embodiment of the present invention, according to the current moment Axis estimated current and current moment Estimated axis current and the motor current at the current moment The actual current of the shaft and the motor at the current moment The actual current of the axis is calculated at the current moment. The proportional integral output of the axis disturbance loop and the current moment The shaft disturbance loop proportional integral output includes:

[0019]

[0020]

[0021] in, For the current moment Shaft disturbance loop proportional integral output, For the current moment Shaft disturbance loop proportional integral output, is the motor d-axis inductance, is the motor q-axis inductance, is the proportional coefficient of the disturbance ring, is the perturbation loop integral coefficient, The motor at the current moment Actual shaft current, The motor at the current moment Actual shaft current, For the current moment Estimated axis current, For the current moment Estimated axis current.

[0022] Among them, calculate the current moment Estimated axis current and the current moment Estimated axis current ,include:

[0023] According to the current motor current, the current motor voltage, the motor estimated angular velocity at the previous moment, the Axis disturbance loop proportional integral output, the last moment The shaft disturbance loop proportional integral output and motor parameters are used to calculate the current moment Axis estimated current and current moment Estimated axis current.

[0024] Calculate the current time Estimated axis current and the current moment Estimated axis current The specific formula is:

[0025]

[0026]

[0027] in, Estimate the angular velocity of the motor at the last moment, For the previous moment Shaft disturbance loop proportional integral output, For the previous moment Shaft disturbance loop proportional integral output.

[0028] Step 12, according to the current moment Axis disturbance loop proportional integral output, current moment The proportional integral output of the axis disturbance loop and the phase angle at the previous moment are used to calculate the phase-locked loop output at the current moment.

[0029] In one embodiment of the present invention, the Axis disturbance loop proportional integral output, current moment The proportional integral output of the axis disturbance loop and the phase angle at the previous moment are used to calculate the phase-locked loop output at the current moment, including:

[0030]

[0031]

[0032] in, For the current moment Shaft disturbance loop proportional integral output, For the current moment Shaft disturbance loop proportional integral output, is the phase-locked loop input at the current moment, is the phase-locked loop output at the current moment, is the phase-locked loop proportional coefficient, is the phase-locked loop integral coefficient, is the phase angle at the previous moment.

[0033] Step 13: Calculate the estimated angular velocity of the motor at the current moment according to the phase-locked loop output at the current moment and the estimated angular velocity of the motor at the previous moment.

[0034] In one embodiment of the present invention, the step of calculating the estimated motor angular velocity at the current moment based on the phase-locked loop output at the current moment and the estimated motor angular velocity at the previous moment includes:

[0035]

[0036] in, Estimate the angular velocity of the motor at the current moment, Estimate the angular velocity of the motor at the last moment, is the observer bandwidth.

[0037] Step 14 : Calculate the current q-axis current given value and the current d-axis current given value based on the motor estimated angular velocity and the motor given angular velocity at the current moment.

[0038] In one embodiment of the present invention, the calculating of the current q-axis current given value and the current d-axis current given value based on the current estimated motor angular velocity and the current given motor angular velocity includes:

[0039]

[0040] in, Estimate the angular velocity of the motor at the current moment, is the given angular velocity of the motor, is the speed loop proportional coefficient, is the speed loop integral coefficient, is the given value of the q-axis current at the current moment.

[0041] When the motor is a permanent magnet synchronous motor, the d-axis current reference value is set to:

[0042]

[0043] The phase angle is calculated as:

[0044]

[0045] in, is the given value of the d-axis current at the current moment, is the phase angle at the current moment.

[0046] The above embodiment describes a method for a centralized control system to calculate the current q-axis current given value, the current d-axis current given value, and the current phase angle when the motor is a synchronous permanent magnet motor. The following describes a method for calculating the current q-axis current given value, the current d-axis current given value, and the current phase angle when the motor is an asynchronous motor.

[0047] In one embodiment of the present invention, when the motor is an asynchronous motor, the step of calculating the q-axis current set value, the d-axis current set value, and the phase angle for outputting control of each submodule based on the motor voltage and the motor current includes:

[0048] Step 11', calculating the voltage setting value according to the motor setting current.

[0049] In one embodiment of the present invention, the step of calculating the voltage setting value based on the motor setting current includes:

[0050]

[0051] in, is the voltage given value, is the voltage-frequency proportional coefficient, Give the motor an angular velocity value.

[0052] Step 12 ′: Calculate the voltage feedback value at the current moment through angle transformation according to the motor voltage at the current moment.

[0053] In one embodiment of the present invention, the step of calculating the voltage feedback value at the current moment by angle transformation based on the motor voltage at the current moment includes:

[0054]

[0055] in, is the voltage feedback value at the current moment, The motor at the current moment Actual shaft voltage, The motor at the current moment Actual shaft voltage.

[0056] Step 13 ′: Calculate the current q-axis current given value, the current d-axis current given value, and the current phase angle according to the voltage given value and the voltage feedback value at the current moment.

[0057] In one embodiment of the present invention, calculating the q-axis current set value at the current moment, the d-axis current set value at the current moment, and the phase angle at the current moment according to the voltage set value and the voltage feedback value at the current moment includes:

[0058]

[0059] When the motor is an asynchronous motor, the d-axis current reference value is set to:

[0060] Calculate the phase angle:

[0061]

[0062]

[0063] in, is the voltage loop proportional coefficient, is the voltage loop integral coefficient, is the given value of the q-axis current at the current moment, is the given value of the d-axis current at the current moment, is the phase angle at the current moment.

[0064] Step 2: Based on the q-axis current given value, the d-axis current given value and the phase angle, each submodule control system calculates and outputs a control duty cycle for controlling each submodule, and controls the corresponding submodule based on the control duty cycle.

[0065] In one embodiment of the present invention, the control system of each submodule calculates and outputs a control duty cycle of each submodule based on the q-axis current set value, the d-axis current set value, and the phase angle, including:

[0066] Step 21 : Calculate the q-axis voltage given value of each submodule according to the q-axis current given value and the actual q-axis current of each submodule.

[0067] Step 22 : Calculate a given d-axis voltage value of each submodule according to the given d-axis current value and the actual d-axis current of each submodule.

[0068] In one embodiment of the present invention, calculating the q-axis voltage set value of each submodule according to the q-axis current set value and the actual q-axis current of each submodule includes:

[0069]

[0070] Calculating a d-axis voltage set value for each submodule according to the d-axis current set value and the actual d-axis current of each submodule, including:

[0071]

[0072] in, is the q-axis voltage given value of the nth submodule at the current moment, is the d-axis voltage given value of the nth submodule at the current moment, N is the number of submodules, is the actual q-axis current of the nth submodule at the current moment, is the actual d-axis current of the nth submodule at the current moment, is the current loop proportional coefficient, is the current loop integral coefficient. and The real-time measurement current of the nth submodule passes through the phase angle Coordinate transformation is obtained.

[0073] Step 23 : Calculate the control duty cycle of each submodule according to the q-axis voltage given value and the d-axis voltage given value of each submodule.

[0074] In one embodiment of the present invention, the control duty cycle of each submodule is calculated based on the q-axis voltage given value and the d-axis voltage given value of each submodule using existing technology. No further explanation is given here. Each submodule is controlled based on the calculated control duty cycle of each submodule to achieve current balancing of multiple submodules.

[0075] See also Figure 2 , provides a multi-module parallel synchronous control system for a high-power converter according to an embodiment of the present invention, the system includes a centralized control system and multiple sub-module control systems;

[0076] The centralized control system is used to calculate the q-axis current set value, d-axis current set value and phase angle of each sub-module for output control based on the motor voltage and motor current and based on the outer-loop closed-loop control algorithm, and send the q-axis current set value, d-axis current set value and phase angle to each sub-module control system; each sub-module control system is used to calculate the control duty cycle of each sub-module for output control based on the q-axis current set value, d-axis current set value and phase angle and based on the inner-loop closed-loop control algorithm, and control the corresponding sub-module based on the control duty cycle.

[0077] In one embodiment of the present invention, the centralized control system and multiple sub-module control systems share one CAN bus and two RS485 buses, wherein the CAN bus is used for medium and low-speed point-to-point communication. The centralized control system receives status feedback and fault feedback uploaded by the sub-module control systems through the CAN bus, and the sub-module control systems receive enable signals sent by the centralized control system through the CAN bus. Each sub-module control system takes turns to communicate point-to-point with the centralized control system.

[0078] One RS485 bus is used for carrier signal synchronization, while the other is used for high-speed broadcast communication. The centralized control system outputs the carrier synchronization signal to the PWM-SyncIn pin of the submodule control circuit via RS485 bus No. 1, with a synchronization interval equal to an integer number of carrier cycles. The centralized control system issues control commands, such as the q-axis current setpoint, d-axis current setpoint, and phase angle, to the submodule control circuit via RS485 bus No. 2. Each communication must contain at least 8 bytes, at a rate of at least 75 kB / s.

[0079] The control sequence of the multi-module parallel synchronous control system is:

[0080] During the kth PWM interrupt, the centralized control system sequentially executes the following: broadcasting the k-1th control instruction, collecting voltage and current signals, executing the outer closed-loop control algorithm, and calculating the kth control instruction. Simultaneously, during the kth PWM interrupt, the submodule control system sequentially executes the following: reading the k-2th control instruction sent by the centralized control system, collecting voltage and current signals, executing the inner closed-loop control algorithm, feeding back the kth status and fault data, and outputting the power device control signal.

[0081] The present invention provides a multi-module parallel synchronous control method for high-power converters. Based on the collected voltage and current at the output ends of the sub-modules and the motor voltage and current, a dual closed-loop control algorithm is used to output power device control signals for each sub-module, thereby realizing variable frequency speed control of the motor load. This method can effectively reduce parallel circulating current, balance the sub-module current, and improve the output power quality of the inverter.

[0082] It should be noted that, in the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0083] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0084] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0085] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0086] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0087] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0088] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A multi-module parallel synchronous control method for a high-power converter, characterized in that: include: According to the motor voltage and motor current, the q-axis current set value, d-axis current set value and phase angle of each submodule are calculated and output based on the outer loop closed-loop control algorithm, and the q-axis current set value, d-axis current set value and phase angle are sent to each submodule control system; According to the q-axis current set value, the d-axis current set value and the phase angle, each submodule control system calculates and outputs a control duty cycle for controlling each submodule based on an inner-loop closed-loop control algorithm, and controls the corresponding submodule based on the control duty cycle; When the motor is a permanent magnet synchronous motor, the calculation of the q-axis current set value, the d-axis current set value, and the phase angle of each submodule for output control based on the motor voltage and the motor current includes: According to the current moment Axis estimated current and current moment Estimated axis current and the motor current at the current moment The actual current of the shaft and the motor at the current moment The actual current of the axis is calculated at the current moment. The proportional integral output of the axis disturbance loop and the current moment Shaft disturbance loop proportional integral output; According to the current moment Axis disturbance loop proportional integral output, current moment The proportional integral output of the axis disturbance loop and the phase angle at the previous moment are used to calculate the phase-locked loop output at the current moment; Calculate the current estimated angular velocity of the motor based on the current phase-locked loop output and the previous estimated angular velocity of the motor; Based on the estimated motor angular velocity and the given motor angular velocity at the current moment, a q-axis current given value and a d-axis current given value at the current moment are calculated.

2. The multi-module parallel synchronous control method for high-power converters according to claim 1, characterized in that: According to the current moment Axis estimated current and current moment Estimated axis current and the motor current at the current moment The actual current of the shaft and the motor at the current moment The actual current of the axis is calculated at the current moment. The proportional integral output of the axis disturbance loop and the current moment The shaft disturbance loop proportional integral output includes: in, For the current moment Shaft disturbance loop proportional integral output, For the current moment Shaft disturbance loop proportional integral output, is the motor d-axis inductance, is the motor q-axis inductance, is the proportional coefficient of the disturbance ring, is the perturbation loop integral coefficient, The motor at the current moment Actual shaft current, The motor at the current moment Actual shaft current, For the current moment Estimated axis current, For the current moment Estimated axis current.

3. The multi-module parallel synchronous control method for high-power converters according to claim 2, characterized in that: Calculate the current time Axis estimated current and current moment Axis estimated current, including: based on the current moment of the motor current, the current moment of the motor voltage, the motor estimated angular velocity at the previous moment, the previous moment of the motor current, the current moment of the motor voltage, the current ... Axis disturbance loop proportional integral output, the last moment The shaft disturbance loop proportional integral output and motor parameters are used to calculate the current moment Axis estimated current and current moment Estimated axis current.

4. The multi-module parallel synchronous control method for high-power converters according to claim 3, characterized in that: The motor current at the current moment, the motor voltage at the current moment, the motor estimated angular velocity at the previous moment, the motor Axis disturbance loop proportional integral output, the last moment The shaft disturbance loop proportional integral output and motor parameters are used to calculate the current moment Axis estimated current and current moment Estimated axis current, including: in, Estimate the angular velocity of the motor at the last moment, For the previous moment Shaft disturbance loop proportional integral output, For the previous moment Shaft disturbance loop proportional integral output, The motor at the current moment Actual shaft voltage, The motor at the current moment Actual shaft voltage.

5. The multi-module parallel synchronous control method for high power converters according to claim 1, characterized in that: According to the current moment Axis disturbance loop proportional integral output, current moment The proportional integral output of the axis disturbance loop and the phase angle at the previous moment are used to calculate the phase-locked loop output at the current moment, including: in, For the current moment Shaft disturbance loop proportional integral output, For the current moment Shaft disturbance loop proportional integral output, is the phase-locked loop input at the current moment, is the phase-locked loop output at the current moment, is the phase-locked loop proportional coefficient, is the phase-locked loop integral coefficient, is the phase angle at the previous moment; The step of calculating the estimated angular velocity of the motor at the current moment according to the phase-locked loop output at the current moment and the estimated angular velocity of the motor at the previous moment includes: in, Estimate the angular velocity of the motor at the current moment, Estimate the angular velocity of the motor at the last moment, is the observer bandwidth.

6. The multi-module parallel synchronous control method for high-power converters according to claim 1, characterized in that: The calculating of the q-axis current given value and the d-axis current given value at the current moment based on the estimated motor angular velocity and the given motor angular velocity at the current moment includes: in, Estimate the angular velocity of the motor at the current moment, is the given angular velocity of the motor, is the speed loop proportional coefficient, is the speed loop integral coefficient, is the given value of the q-axis current at the current moment, is the given value of the d-axis current at the current moment, is the phase angle at the current moment.

7. The multi-module parallel synchronous control method for high power converters according to claim 1, characterized in that: When the motor is an asynchronous motor, the calculation of the q-axis current set value, the d-axis current set value, and the phase angle of each submodule for output control based on the motor voltage and the motor current includes: Calculate the voltage given value according to the motor given current; Calculate the voltage feedback value at the current moment according to the motor voltage at the current moment; According to the voltage given value and the voltage feedback value at the current moment, the q-axis current given value at the current moment, the d-axis current given value at the current moment and the phase angle at the current moment are calculated.

8. The multi-module parallel synchronous control method for high-power converters according to claim 7, characterized in that: The step of calculating the voltage setting value according to the motor setting current includes: in, is the voltage given value, is the voltage-frequency proportional coefficient, Give the motor an angular velocity value; The step of calculating the voltage feedback value at the current moment according to the motor voltage at the current moment includes: in, is the voltage feedback value at the current moment, The motor at the current moment Actual shaft voltage, The motor at the current moment Actual shaft voltage; Calculating a q-axis current given value at the current moment, a d-axis current given value at the current moment, and a phase angle at the current moment according to the voltage given value and the voltage feedback value at the current moment, including: in, is the voltage loop proportional coefficient, is the voltage loop integral coefficient, is the given value of the q-axis current at the current moment, is the given value of the d-axis current at the current moment, is the phase angle at the current moment.

9. The multi-module parallel synchronous control method for high power converters according to claim 1, characterized in that: The control system of each submodule calculates and outputs a control duty cycle of each submodule according to the q-axis current given value, the d-axis current given value and the phase angle, including: According to the q-axis current given value and the actual q-axis current of each submodule, the q-axis voltage given value of each submodule is calculated: Calculating a d-axis voltage set value for each submodule based on the d-axis current set value and the actual d-axis current of each submodule; Calculating a control duty cycle of each submodule according to the q-axis voltage given value and the d-axis voltage given value of each submodule; Calculating the q-axis voltage given value of each submodule according to the q-axis current given value and the actual q-axis current of each submodule includes: The step of calculating the d-axis voltage given value of each submodule according to the d-axis current given value and the actual d-axis current of each submodule includes: in, is the q-axis voltage given value of the nth submodule at the current moment, is the d-axis voltage given value of the nth submodule at the current moment, N is the number of submodules, is the actual d-axis current of the nth submodule at the current moment, is the actual q-axis current of the nth submodule at the current moment, is the current loop proportional coefficient, is the current loop integral coefficient, is the given value of the q-axis current at the current moment, is the given value of the d-axis current at the current moment.

Images