A high-efficiency control method for high-power drive system

Abstract

The application discloses a high-efficiency control method for a high-power driving system. The application simultaneously considers inverter efficiency and motor efficiency, and selects optimal current instruction and modulation mode on line according to actual operation conditions. The current calibration method is adopted, first, the current regulation angle is given at the corresponding speed to maximize the output torque. On this basis, the modulation mode calibration is carried out, the SVPWM and four kinds of DPWM (DPWM0, DPWM1, DPWM2, DPWM3) are respectively used for modulation output, and the corresponding modulation mode when the minimum power input is determined. Finally, the current and modulation mode corresponding to the current speed and torque are made into a table, and the electric driving system is controlled efficiently through the table lookup method.

Description

Technical Field

[0001] This invention relates to a high-efficiency control method for high-power drive systems, belonging to the field of motor control. Background Technology

[0002] As the power system of electric heavy-duty trucks, the efficiency of the high-power electric drive system determines the mileage that the truck can travel with the same amount of electricity. To achieve a higher mileage for electric heavy-duty trucks, the efficiency of the electric drive system must be improved.

[0003] Existing technologies reduce losses at both the inverter and motor levels. The inverter primarily employs DPWM modulation, while the motor mainly uses model-based control methods. However, these existing technologies do not consider the electric drive system as a whole, resulting in the following problems:

[0004] 1) When a certain DPWM modulation is used, although the inverter loss is reduced, the output current harmonics increase, which leads to increased motor loss and reduced overall efficiency of the electric drive system.

[0005] 2) Only when the inverter output power factor and modulation index remain constant can a specific DPWM modulation strategy reduce inverter losses. However, when the electric drive system is working, the modulation index and power factor are constantly changing.

[0006] 3) The motor control method based on the loss model is based on a mathematical model and depends on the motor parameters. When the motor is working in different states, the change of motor parameters leads to an increase in losses. Summary of the Invention

[0007] Objective: To address the problem of unpredictable operating conditions in electric drive systems and the variation of motor parameters with these conditions, this invention treats the electric drive system as a whole and proposes an efficient control method for high-power drive systems.

[0008] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides an efficient control method for a high-power drive system, comprising:

[0010] The current magnitude, current angle, and modulation method of the inverter under the current operating condition are determined by looking up the instruction table according to the current operating condition of the electric drive system. The operating condition includes speed and torque, and the instruction table contains the correspondence between speed, torque, current magnitude, current angle, and modulation method.

[0011] Based on the actual current and the determined current magnitude and current angle, the initial modulation wave signal is output through closed-loop PI control.

[0012] Based on the initial modulated wave signal and the determined modulation method, the corresponding zero-sequence component is obtained;

[0013] The corresponding zero-sequence component is superimposed on the output initial modulated wave signal to obtain the given modulated wave signal;

[0014] The electric drive system is controlled according to the given modulation wave signal.

[0015] The modulation methods include SVPWM modulation, DPWM0 modulation, DPWM1 modulation, DPWM2 modulation, and DPWM3 modulation.

[0016] In some embodiments, the method for obtaining the instruction table includes:

[0017] Step S11: Perform current calibration: At a given speed n, provide a current magnitude i, adjust the current angle to maximize the motor output torque, and record the current angle γ and torque T corresponding to the maximum output torque at speed n and current magnitude i. max ;

[0018] Step S12: Based on step S11, perform modulation mode calibration: Modulate the output using SVPWM, DPWM0, DPWM1, DPWM2, and DPWM3 modulation modes respectively, compare the input power of the electric drive system under each modulation mode, and determine the modulation mode corresponding to the minimum input power of the electric drive system; obtain the current angle γ and torque T corresponding to the rotational speed n and current magnitude i. max and modulation method m;

[0019] Step S13: Adjust the given current at speed n, and repeat steps S11 to S12 until the motor output torque reaches the maximum torque of the motor, so as to obtain the current angle, torque and modulation method corresponding to various current magnitudes at speed n.

[0020] Step S14: Following the methods in steps S11 to S13, calibrate the corresponding relationships between current magnitude, current angle, and modulation method for various torques across the entire speed range, and store them in the instruction table.

[0021] Furthermore, before obtaining the current angle, torque, and modulation method corresponding to various current magnitudes at rotational speed n, the following steps are also included:

[0022] By fitting the recorded torque, current angle, and modulation data corresponding to all current magnitudes at rotational speed n, we can obtain the torque, current angle, and modulation method corresponding to the total current magnitude at rotational speed n.

[0023] Furthermore, before obtaining the correspondence between the current magnitude, current angle, and modulation method corresponding to various torques across the entire speed range, the process also includes: fitting the recorded data of torque, current angle, and modulation method corresponding to various current magnitudes across the entire speed range.

[0024] In some embodiments, obtaining the corresponding zero-sequence component based on the initial modulated wave signal and the determined modulation scheme includes:

[0025]

[0026] Among them, u z For the zero-order component, u min u max The three phases of the initial modulation wave signal are respectively The minimum and maximum values ​​in the equation are given, where k is the coefficient corresponding to different modulation methods m.

[0027] Furthermore, obtaining the corresponding zero-sequence component based on the initial modulated wave signal and modulation scheme further includes:

[0028] SVPWM modulation method: u z =0;

[0029] DPWM0 modulation mode: In the 12 sectors, the initial modulation wave signal is k=1 in sectors 3, 4, 7, 8, 11, and 12, and k=0 in other sectors;

[0030] DPWM1 modulation mode: In the 12 sectors, the initial modulation wave signal is k=1 in sectors 1, 4, 5, 8, 9, and 12, and k=0 in other sectors;

[0031] DPWM2 modulation method: In the 12 sectors, the initial modulation wave signal is k=1 in sectors 1, 2, 5, 6, 9, and 10, and k=0 in other sectors;

[0032] DPWM3 modulation mode: In the 12 sectors, the initial modulation wave signal is k=1 in sectors 2, 3, 6, 7, 10, and 11, and k=0 in other sectors.

[0033] In some embodiments, controlling the electric drive system according to the given modulation wave signal includes:

[0034] The given modulated wave signal is compared with a triangular carrier wave, and a drive signal is output to control the inverter based on the comparison result.

[0035] In a second aspect, the present invention provides a high-efficiency control system for a high-power drive system, including a processor and a storage medium;

[0036] The storage medium is used to store instructions;

[0037] The processor is configured to operate according to the instructions to perform the steps of the method according to the first aspect.

[0038] Thirdly, the present invention provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect.

[0039] Beneficial effects: The efficient control method for high-power drive systems provided by this invention has the following advantages compared with traditional methods:

[0040] (1) By using the calibration method, the optimal current and modulation method corresponding to the current speed and torque are stored in the instruction table for lookup control, which avoids the increase in losses caused by the failure of the minimum loss control algorithm due to parameter changes of the motor under different operating conditions.

[0041] (2) Treat the motor controller and the motor as a whole, with the goal of improving the efficiency of the electric drive system. Although using specific DPWM modulation can increase the efficiency of the motor controller, the increase in motor losses due to the increase in the output harmonics of the motor controller may lead to a decrease in the efficiency of the electric drive system.

[0042] (3) Different modulation strategies are adopted for different operating conditions so that the electric drive system can achieve the best efficiency under any operating condition. Using fixed DPWM modulation can only improve efficiency when the electric drive system is operating within a fixed speed and torque range. However, the speed and torque of the electric drive system are constantly changing. When the speed and torque change, the power factor and modulation degree of the motor controller also change, resulting in an increase in motor controller losses under the current DPWM modulation method. Attached Figure Description

[0043] Figure 1 This is a control block diagram of an embodiment of the present invention;

[0044] Figure 2 This is a diagram showing the PWM sector division in the embodiment;

[0045] Figure 3 This is a flowchart illustrating the instruction table generation method according to an embodiment of the present invention. Detailed Implementation

[0046] To more clearly illustrate the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings. The specific embodiments described are only for explaining the present invention and are not intended to limit the present invention.

[0047] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0048] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] Example 1

[0050] An efficient control method for high-power drive systems includes:

[0051] The current magnitude, current angle, and modulation method of the inverter under the current operating condition are determined by looking up the instruction table according to the current operating condition of the electric drive system. The operating condition includes speed and torque, and the instruction table contains the correspondence between speed, torque, current magnitude, current angle, and modulation method.

[0052] Based on the actual current and the determined current magnitude and current angle, the initial modulation wave signal is output through closed-loop PI control.

[0053] Based on the initial modulated wave signal and the determined modulation method, the corresponding zero-sequence component is obtained;

[0054] The corresponding zero-sequence component is superimposed on the output initial modulated wave signal to obtain the given modulated wave signal;

[0055] The electric drive system is controlled according to the given modulation wave signal.

[0056] In some embodiments, such as Figure 1 As shown, an efficient control method for high-power drive systems includes:

[0057] (1) The instruction generation module generates the torque instruction T issued by the vehicle controller. e * Based on the detected actual rotational speed n, look up the instruction table and output i. d i qCurrent command (current magnitude and current angle) and modulation method.

[0058] The instruction table includes torque instruction T. e * The correspondence between the actual rotational speed n and the commanded current magnitude i, current angle γ0, and modulation method m. The command table is obtained in the following way, and its flowchart is as follows. Figure 3 As shown.

[0059] Step 1: Perform current calibration on the test bench: Set the dynamometer to speed mode and drive the motor to rotate at speed n0 (e.g., 200 rpm). Set the electric drive system to current mode, set the current magnitude i0 (e.g., 30A), and adjust the current angle γ. When the motor output torque reaches its maximum value T... 0max At the same time, record the current speed n0, current magnitude i0, current angle γ0, and torque T. 0max .

[0060] Step 2, Modulation mode calibration: Based on Step 1, five modulation modes are used respectively: Modulation Mode 1 (SVPWM modulation), Modulation Mode 2 (DPWM0 modulation), Modulation Mode 3 (DPWM1 modulation), Modulation Mode 4 (DPWM2 modulation), and Modulation Mode 5 (DPWM3 modulation) to perform modulation output. The input power P of the electric drive system under each modulation mode is measured using a power analyzer. in Record the minimum input power P of the electric drive system inmin The corresponding modulation scheme is m0. The input power of the electric drive system includes the input power of the inverter and the motor.

[0061] Step 3: Increase the given current magnitude, repeat the above steps, and record the current rotational speed n, current magnitude i, current angle γ, and torque T. max And the modulation method m. Until the maximum torque point of the motor is calibrated, the recorded data is subjected to curve fitting.

[0062] Step 4: Calibrate and perform curve fitting on the full speed range of the motor using the method described above, and store the fitted curve in the instruction table.

[0063] (2) PI regulation module: The error between the command current and the actual current is used as the input signal to track and control the command current.

[0064] (3) Voltage conversion module, which converts the voltage output by the PI adjustment module in the rotating coordinate system into the voltage in the stationary coordinate system.

[0065] (4) PWM modulation module, performs PWM modulation output. Based on the modulation mode m output from the instruction table, the corresponding zero-sequence component u is obtained. z The expression for the zero-order component is:

[0066]

[0067] in, Given the initial modulated wave signal without superimposed zero-sequence components, the zero-sequence component u can be calculated based on the k value corresponding to different modulation schemes m. z .

[0068] The correspondence between the modulation scheme m and the value of k is as follows:

[0069] m=1, corresponding to modulation mode 1 (SVPWM modulation): the initial modulation wave does not have a zero-sequence component superimposed, i.e., u z =0; m=2, corresponding to modulation mode 2 (DPWM0 modulation): the initial modulation wave is superimposed with the zero-sequence component. In the 12 sectors, the initial modulation wave signal k=1 in sectors 3, 4, 7, 8, 11, and 12, and k=0 in other sectors; m=3, corresponding to modulation mode 3 (DPWM1 modulation): the initial modulation wave is superimposed with the zero-sequence component. In the 12 sectors, the initial modulation wave signal k=1 in sectors 1, 4, 5, 8, 9, and 12, and k=0 in other sectors. 0; m=4, corresponding to modulation mode 4 (DPWM2 modulation): the initial modulation wave is superimposed with the zero-sequence component. In the 12 sectors, the initial modulation wave signal k=1 in sectors 1, 2, 5, 6, 9, and 10, and k=0 in other sectors; m=5, corresponding to modulation mode 5 (DPWM3 modulation): the initial modulation wave is superimposed with the zero-sequence component. In the 12 sectors, the initial modulation wave signal k=1 in sectors 2, 3, 6, 7, 10, and 11, and k=0 in other sectors;

[0070] The 12-sector diagram of the initial modulated wave signal is as follows Figure 2 As shown.

[0071] The obtained zero-order component u z The new modulation wave is superimposed on the initial modulation wave and used as a given modulation wave. It is compared with the triangular carrier wave to output a drive signal for inverter control.

[0072] Compared with traditional methods, the above method,

[0073] (1) By using the calibration method, the optimal current and modulation method corresponding to the current speed and torque are stored in the instruction table for lookup control, which avoids the increase in losses caused by the failure of the minimum loss control algorithm due to parameter changes of the motor under different operating conditions.

[0074] (2) Treat the motor controller and the motor as a whole, with the goal of improving the efficiency of the electric drive system. Although using specific DPWM modulation can increase the efficiency of the motor controller, the increase in motor losses due to the increase in the output harmonics of the motor controller may lead to a decrease in the efficiency of the electric drive system.

[0075] (3) Different modulation strategies are adopted for different operating conditions so that the electric drive system can achieve the best efficiency under any operating condition. Using fixed DPWM modulation can only improve efficiency when the electric drive system is operating within a fixed speed and torque range. However, the speed and torque of the electric drive system are constantly changing. When the speed and torque change, the power factor and modulation degree of the motor controller also change, resulting in an increase in motor controller losses under the current DPWM modulation method.

[0076] It is worth noting that the modules included in the above-described efficient control method for high-power drive systems are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved. The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

[0077] Example 2

[0078] Secondly, this embodiment provides a high-efficiency control system for a high-power drive system, including a processor and a storage medium;

[0079] The storage medium is used to store instructions;

[0080] The processor is configured to operate according to the instructions to perform the steps of the method according to Embodiment 1.

[0081] Example 3

[0082] Thirdly, this embodiment provides a storage medium on which a computer program is stored, which, when executed by a processor, implements the steps of the method described in Embodiment 1.

[0083] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0084] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations 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, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0085] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0086] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0087] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-efficiency control method for a high-power drive system, characterized in that, include: The current magnitude, current angle, and modulation method of the inverter under the current operating condition are determined by looking up the instruction table according to the current operating condition of the electric drive system. The operating condition includes speed and torque, and the instruction table contains the correspondence between speed, torque, current magnitude, current angle, and modulation method. Based on the actual current and the determined current magnitude and current angle, the initial modulation wave signal is output through closed-loop PI control. Based on the initial modulated wave signal and the determined modulation method, the corresponding zero-sequence component is obtained; The corresponding zero-sequence component is superimposed on the output initial modulated wave signal to obtain the given modulated wave signal; The electric drive system is controlled according to the given modulation wave signal; The method for obtaining the instruction table includes: Step S11: Perform current calibration: At a given speed n, provide a current magnitude i, adjust the current angle to maximize the motor output torque, and record the current angle γ and torque T corresponding to the maximum output torque at speed n and current magnitude i. max ; Step S12: Based on step S11, perform modulation mode calibration: Modulate the output using SVPWM, DPWM0, DPWM1, DPWM2, and DPWM3 modulation modes respectively. Compare the input power of the electric drive system under each modulation mode, determine the modulation mode corresponding to the minimum input power of the electric drive system, and obtain the current angle γ and torque T corresponding to the rotational speed n and current magnitude i. max and modulation method m; Step S13: Adjust the given current at speed n, and repeat steps S11 to S12 until the motor output torque reaches the maximum torque of the motor, so as to obtain the current angle, torque and modulation method corresponding to various current magnitudes at speed n. Step S14: Following the methods in steps S11 to S13, calibrate the corresponding relationships between current magnitude, current angle, and modulation method for various torques across the entire speed range, and store them in the instruction table.

2. The method according to claim 1, characterized in that, The modulation methods include SVPWM modulation, DPWM0 modulation, DPWM1 modulation, DPWM2 modulation, and DPWM3 modulation.

3. The method according to claim 1, characterized in that, Before obtaining the current angle, torque, and modulation method corresponding to various current magnitudes at rotational speed n, the following steps are also included: By fitting the recorded torque, current angle, and modulation data corresponding to all current magnitudes at rotational speed n, we can obtain the torque, current angle, and modulation method corresponding to the total current magnitude at rotational speed n.

4. The method according to claim 1, characterized in that, Before obtaining the correspondence between current magnitude, current angle and modulation method for various torques across the entire speed range, the process also includes: fitting the recorded data of torque, current angle and modulation method corresponding to various current magnitudes across the entire speed range.

5. The method according to claim 1, characterized in that, Based on the initial modulated wave signal and the determined modulation scheme, the corresponding zero-sequence component is obtained, including: Among them, u z For the zero-order component, u min u max The three phases of the initial modulation wave signal are respectively The minimum and maximum values ​​in the equation are given, where k is the coefficient corresponding to different modulation methods m.

6. The method according to claim 5, characterized in that, Based on the initial modulated wave signal and the modulation scheme, the corresponding zero-sequence component is obtained, further comprising: SVPWM modulation method: u z =0; DPWM0 modulation mode: In the 12 sectors, the initial modulation wave signal is k=1 in sectors 3, 4, 7, 8, 11, and 12, and k=0 in other sectors; DPWM1 modulation mode: In the 12 sectors, the initial modulation wave signal is k=1 in sectors 1, 4, 5, 8, 9, and 12, and k=0 in other sectors; DPWM2 modulation method: In the 12 sectors, the initial modulation wave signal is k=1 in sectors 1, 2, 5, 6, 9, and 10, and k=0 in other sectors; DPWM3 modulation mode: In the 12 sectors, the initial modulation wave signal is k=1 in sectors 2, 3, 6, 7, 10, and 11, and k=0 in other sectors.

7. The method according to claim 1, characterized in that, Controlling the electric drive system according to the given modulation wave signal includes: The given modulated wave signal is compared with a triangular carrier wave, and a drive signal is output to control the inverter based on the comparison result.

8. A high-efficiency control system for a high-power drive system, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1 to 7.

9. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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