Method for controlling PWM phase difference of vehicle-mounted double-electric-drive system

Abstract

The invention relates to the technical field of PWM phase difference control, and discloses a vehicle-mounted double-electric-drive system PWM phase difference control method, which comprises a rotor angle difference processing unit, a rotor angle difference-PWM reference phase difference table look-up unit, a PWM reference phase difference instruction slope control unit, a PWM reference phase difference control enabling detection unit and a PI controller, the system comprises a dual-motor PWM reference starting point timestamp capturing and phase difference calculating unit, a PWM reference phase difference setting unit, an A motor PWM wave sending unit and a B motor PWM wave sending unit. A PWM reference phase difference instruction is obtained through a rotor angle difference-PWM reference phase difference look-up table, the PWM reference phase difference of the two motors is adjusted and controlled through the PI controller, and the phase difference of PWM signals for driving the A semiconductor module and the B semiconductor module is adjusted and smoothly controlled in real time. Therefore, the ripple current generated by the direct-current capacitor in the vehicle-mounted driving system is more reliably counteracted, and the ripple current in the direct-current capacitor is reduced.

Description

Technical Field

[0001] This invention relates to the field of PWM phase difference control technology, specifically a method for controlling the PWM phase difference in an on-board dual electric drive system. Background Technology

[0002] In recent years, with the rapid growth of new energy vehicles, they have played a crucial role in energy conservation and emission reduction. In the existing dual-motor drive system, motors A and B are controlled by a processor. Under this condition, the semiconductor module of drive A and the semiconductor module of drive B share a DC capacitor.

[0003] In existing technologies, the phase difference of the PWM signals of the drive semiconductor module A and the drive semiconductor module B can be controlled based on the phase difference of the output current vectors of the two motors. This allows the ripple current generated by the DC capacitor in the vehicle drive system to cancel each other out, reducing the ripple current in the DC capacitor and lowering the heating of the DC capacitor, thereby reducing the size of the DC capacitor. In reality, the currents of the two motors are controlled relatively independently. When turning or slipping, the speeds of the two motors become asynchronous, causing a large sudden change in the phase difference of the current vectors of the two motors. If the phase difference of the PWM signals of the drive semiconductor module A and the drive semiconductor module B is directly controlled, it will affect the actual 6-channel PWM output of the motor, causing current control problems.

[0004] Therefore, real-time and smooth control of the phase difference between the PWM signals driving semiconductor module A and semiconductor module B is the key to achieving ripple current cancellation technology.

[0005] In view of this, we propose a control method for the PWM phase difference of an on-board dual electric drive system. Summary of the Invention

[0006] The purpose of this invention is to provide a control method for the PWM phase difference of an on-board dual electric drive system to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for controlling the PWM phase difference of an on-board dual electric drive system includes a rotor angle difference processing unit, a rotor angle difference-PWM reference phase difference lookup table unit, a PWM reference phase difference command slope control unit, a PWM reference phase difference control enable detection unit, a PI controller, a dual-motor PWM reference start point timestamp capture and phase difference calculation unit, a PWM reference phase difference setting unit, an A motor PWM wave generation unit, and a B motor PWM wave generation unit.

[0009] The rotor angle difference processing unit is used to calculate the electrical angle phase difference Δθ between the two motors based on the electrical angle of the rotor position of motor A and the electrical angle of the rotor position of motor B.

[0010] The PWM reference phase difference command slope control unit is used to detect the PWM reference phase difference when the Enable signal output by the PWM reference phase difference control enable detection unit is enabled. When Enable is detected, the value is controlled according to a certain slope to the PWM reference phase difference command reference. The control process obtains the PWM reference phase difference command.

[0011] The PWM reference phase difference control enable detection unit is used to detect the enable conditions of PWM reference phase difference control, including the PWM signal frequencies of the driving semiconductor module A and the driving semiconductor module B being the same, the rotor position decoding of the two motors being fault-free, and the speed of the two motors being the same. After comprehensive analysis, the enable signal Enable is output and anti-jitter processing is performed.

[0012] Preferably, the rotor angle difference-PWM reference phase difference lookup table unit is used to obtain the PWM reference phase difference command reference based on the electrical angle phase difference between the two motors.

[0013] Preferably, the reference phase difference command is used for PWM. By controlling the PWM reference phase difference between the two motors, the ripple current generated by the DC capacitor in the dual drive system can be mutually canceled, reducing the ripple current in the DC capacitor. The rotor angle difference-PWM reference phase difference table can be obtained through theoretical calculation and bench verification or bench calibration.

[0014] Preferably, when the Enable signal output by the PWM reference phase difference control enable detection unit is disabled, the value of the PWM reference phase difference command φ_Cmd remains unchanged at the moment when Enable is detected.

[0015] Preferably, the PI controller is used to measure the measured PWM reference phase difference when the Enable signal output by the PWM reference phase difference control enable detection unit is enabled. and PWM reference phase difference command The PWM register count value CNT_Diff is dynamically adjusted by the PI controller to output the PWM reference phase difference.

[0016] Preferably, when the Enable signal output by the PWM reference phase difference control enable detection unit is disabled, the PI controller performs deintegration and other related processing.

[0017] Preferably, the dual-motor PWM reference start point timestamp capture and phase difference calculation unit is used to capture the PWM reference start point timestamps of the two motors, and at the same time calculate the PWM reference phase difference φ_Fbk based on the switching cycle.

[0018] Preferably, the PWM reference phase difference setting unit is used to set the PWM reference phase difference PWM register count value CNT_Diff output by the PI controller to the PWM reference of motor B when the signal Enable output by the PWM reference phase difference control enable detection unit is enabled, so as to change the PWM reference phase difference between the two motors.

[0019] Among them, the PWM reference phase of motor A does not need to be processed. When the Enable signal output by the PWM reference phase difference control enable detection unit is disabled, the PWM reference phase of motor B also does not need to be processed.

[0020] Preferably, the PWM wave generation unit for motor A is used to control the PWM wave generation of motor A based on the PWM reference of motor A, including 6-channel PWM output, FOC trigger output, current sampling trigger output, etc.

[0021] Preferably, the B motor PWM ripple generation unit is used to control the PWM ripple generation of the B motor based on the PWM reference of the B motor after phase difference control, including 6-channel PWM output, FOC trigger output, current sampling trigger output, etc.

[0022] By employing the above technical solution, the present invention provides a method for controlling the PWM phase difference of an on-board dual electric drive system. It possesses at least the following beneficial effects:

[0023] (1) The present invention obtains the PWM reference phase difference instruction by looking up the table of rotor angle difference-PWM reference phase difference, and adjusts and controls the PWM reference phase difference of the two motors by PI controller, and adjusts and controls the phase difference of the PWM signals of the drive semiconductor module A and the drive semiconductor module B in real time, thereby more reliably realizing the mutual cancellation of the ripple current generated by the DC capacitor in the vehicle drive system and reducing the ripple current in the DC capacitor.

[0024] (2) By setting a PWM reference phase difference command slope control unit, the present invention makes the rise or fall of the PWM reference phase difference more stable through slope control, thereby avoiding motor control problems caused by sudden changes in the PWM reference phase difference.

[0025] (3) By setting up a PI controller and using PWM reference phase difference closed-loop control, the present invention achieves fast response and precise control, thereby improving the stability of the system. Attached Figure Description

[0026] The accompanying drawings, which are provided to further illustrate the invention, constitute a part of this application:

[0027] Figure 1 This is a schematic diagram of the overall scheme of the present invention;

[0028] Figure 2 This is a schematic diagram of the PWM reference phase difference output of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figures 1-2 As shown, this invention proposes a control method for PWM phase difference in a vehicle-mounted dual electric drive system, comprising: a rotor angle difference processing unit, a rotor angle difference-PWM reference phase difference lookup table unit, a PWM reference phase difference command slope control unit, a PWM reference phase difference control enable detection unit, a PI controller, a dual-motor PWM reference start point timestamp capture and phase difference calculation unit, a PWM reference phase difference setting unit, an A motor PWM wave generation unit, and a B motor PWM wave generation unit;

[0031] The rotor angle difference processing unit is used to calculate the electrical angle phase difference Δθ between the two motors based on the electrical angle of the rotor position of motor A and the electrical angle of the rotor position of motor B.

[0032] The rotor angle difference processing unit acquires the rotor position electrical angle ΔA of motor A and the rotor position electrical angle ΔB of motor B in real time, and calculates the electrical angle phase difference Δθ between the two motors. Δθ reflects the relative position difference between the rotors of the two motors in space.

[0033] The PWM reference phase difference command slope control unit is used to detect the PWM reference phase difference when the Enable signal output by the PWM reference phase difference control enable detection unit is enabled. When Enable is detected, the value is controlled according to a certain slope to the PWM reference phase difference command reference. The control process obtains the PWM reference phase difference command.

[0034] When Enable = 1, the PWM reference phase difference command slope control unit begins operation. This is achieved by acquiring the currently measured PWM reference phase difference feedback value. and the target instruction reference value obtained from the query The unit does not immediately jump the instruction to Instead, from the current Starting with the given value, the command value is gradually adjusted according to a preset rising or falling slope (this slope can be set according to system response requirements to ensure a smooth transition). The intermediate command value generated during this smooth transition is the final output PWM reference phase difference command. This slope control mechanism effectively avoids the impact of sudden changes in phase difference commands on motor current control.

[0035] When Enable = 0 (disabled), the PWM reference phase difference command slope control unit stops working and remains in this state. At this time, the output PWM reference phase difference command... The value remains unchanged from the last time Enable was detected to change from 0 to 1 (i.e., the last time enable started), or it remains unchanged from the last valid output value. The changes no longer affect

[0036] The PWM reference phase difference control enable detection unit is used to detect the enable conditions of PWM reference phase difference control, including the PWM signal frequencies of the driving semiconductor module A and the driving semiconductor module B being the same, the rotor position decoding of the two motors being fault-free, and the speed of the two motors being the same. After comprehensive analysis, the enable signal Enable is output and anti-jitter processing is performed.

[0037] The PWM reference phase difference control enable detection unit continuously detects and determines whether the conditions for performing PWM phase difference control are met. These conditions must be met simultaneously as follows:

[0038] The PWM carrier signal frequencies of the semiconductor module (inverter A) of drive motor A and the semiconductor module (inverter B) of drive motor B are the same.

[0039] The rotor position sensors of motors A and B both functioned without fault, ensuring that the signals were valid and reliable.

[0040] The actual rotational speeds of motor A and motor B are the same, or within the allowable minimum error range;

[0041] The PWM reference phase difference control enable detection unit comprehensively judges the above conditions. If all conditions are met, the enable signal Enable = 1 (valid / enabled) is output; if any condition is not met, the enable signal Enable = 0 (invalid / disabled) is output. To prevent signal jitter from causing malfunctions, the unit performs anti-jitter filtering on the output signal Enable (such as delayed confirmation or filtering algorithm).

[0042] The rotor angle difference-PWM reference phase difference lookup table unit is used to obtain the PWM reference phase difference command reference based on the electrical angle phase difference between the two motors.

[0043] The rotor angle difference-PWM reference phase difference lookup table unit receives the calculated electrical angle phase difference Δθ. Based on Δθ, it looks up a preset rotor angle difference-PWM reference phase difference mapping table to obtain the corresponding target PWM reference phase difference command reference value. This mapping table defines the ideal PWM phase difference value that should be set for different rotor angle differences Δθ in order to achieve mutual cancellation of DC capacitor ripple current. This mapping table can be obtained through theoretical calculations (such as based on the principle of motor current waveform and ripple current cancellation) combined with bench tests or directly through bench calibration.

[0044] Reference to PWM reference phase difference command By controlling the PWM reference phase difference between the two motors, the ripple current generated by the DC capacitor in the dual drive system can be mutually canceled, reducing the ripple current in the DC capacitor. The rotor angle difference-PWM reference phase difference table can be obtained through theoretical calculation and bench verification or bench calibration.

[0045] When the Enable signal output by the PWM reference phase difference control enable detection unit is disabled, the value of the PWM reference phase difference command φ_Cmd remains unchanged when Enable is detected.

[0046] The PI controller is used to measure the measured PWM reference phase difference when the Enable signal output by the PWM reference phase difference control enable detection unit is enabled. and PWM reference phase difference command The PWM register count value CNT_Diff is dynamically adjusted by the PI controller to output the PWM reference phase difference.

[0047] When Enable=1, the PI controller receives the generated PWM reference phase difference command. And the calculated measured PWM reference phase difference feedback value Controller calculation error e = And perform proportional-integral (PI) calculation on this error:

[0048] CNT_Diff = K p *e+K i *∫e dt

[0049] Among them, K p K is the proportionality coefficient. iThis is the integral coefficient. The output CNT_Diff of the PI operation is a PWM register count value, which directly corresponds to the time offset (in counter clock cycles) that needs to be applied to the PWM reference start point of motor B. The PI controller dynamically adjusts CNT_Diff with the goal of making... Track quickly and accurately Achieve closed-loop control of phase difference;

[0050] When Enable = 0 (disabled), the PI controller stops integration (to prevent integral saturation) and performs other necessary anti-saturation or reset processing (such as clearing or maintaining the integral term). The output CNT_Diff is usually kept at 0 or unchanged (depending on the processing logic in step 7). The controller is in standby mode.

[0051] When the Enable signal output by the PWM reference phase difference control enable detection unit is disabled, the PI controller performs deintegration and other related processing.

[0052] The dual-motor PWM reference start point timestamp capture and phase difference calculation unit is used to capture the PWM reference start point timestamps of the two motors, and at the same time calculate the PWM reference phase difference φ_Fbk based on the switching cycle;

[0053] The dual-motor PWM reference start point timestamp capture and phase difference calculation unit is responsible for:

[0054] Capture timestamps: Within each PWM switching cycle, accurately capture the timestamp T_A of the start point of the PWM carrier counter of motor A (usually corresponding to the moment the counter returns to zero or reaches full) and the timestamp T_B of the start point of the PWM carrier counter of motor B. This is typically achieved using the processor's timer capture function.

[0055] Calculate the phase difference: Based on the captured timestamps T_A and T_B, and the known PWM switching period T_sw, calculate the actual time difference Δ between the current PWM reference start points of the two motors. t :

[0056] Δ t =|T_A-T_B|

[0057] This time difference is then converted into a phase difference (usually expressed in angles, ranging from 0° to 360° or 0 to 1.0 pu):

[0058] φ_Fbk=(Δ t / T_sw)*360°

[0059] The calculated φ_Fbk is the measured PWM reference phase difference feedback value.

[0060] The PWM reference phase difference setting unit is used to set the PWM reference phase difference PWM register count value CNT_Diff output by the PI controller to the PWM reference of motor B when the signal Enable output by the PWM reference phase difference control enable detection unit is enabled, so as to change the PWM reference phase difference between the two motors.

[0061] Among them, the PWM reference phase of motor A does not need to be processed. When the Enable signal output by the PWM reference phase difference control enable detection unit is disabled, the PWM reference phase of motor B also does not need to be processed.

[0062] When Enable=1, the PWM reference phase difference setting unit receives the CNT_Diff value output by the PI controller. This unit does not change the PWM reference start point of motor A (i.e., the start point of the PWM carrier counter of motor A remains unchanged). For motor B, the unit sets (writes) the CNT_Diff value to the hardware register controlling the PWM generation of motor B. This CNT_Diff value causes the start point of the PWM carrier counter of motor B to be offset by CNT_Diff count clock cycles relative to its original set point (or relative to the start point of motor A), thereby actively changing the actual phase difference between the PWM reference signals of the two motors.

[0063] When Enable = 0 (disabled), the PWM reference phase difference setting unit stops adjusting the PWM reference start point of motor B. At this time, the PWM reference start point register value of motor B remains unchanged or returns to its default value (usually 0, i.e., no offset), meaning there is no phase difference actively introduced by this method between the PWM reference start points of motors A and B. The PWM reference phase of motor A never needs to be processed by this unit.

[0064] The A motor PWM wave generation unit is used to control the PWM wave generation of the A motor based on the PWM reference of the A motor, including 6 PWM outputs, FOC trigger output, current sampling trigger output, etc.

[0065] The motor A PWM generation unit generates six complementary PWM signals to drive the power devices in inverter A, based on the motor A's own PWM reference (including its unchanged carrier start point) and the voltage vector command generated by the motor control algorithm (such as the FOC algorithm). Simultaneously, this unit also generates key event trigger signals synchronized with the PWM, such as the FOC algorithm execution trigger signal and the phase current sampling trigger signal.

[0066] The B motor PWM wave generation unit is used to control the PWM wave generation of the B motor based on the PWM reference of the B motor after phase difference control, including 6-channel PWM output, FOC trigger output, current sampling trigger output, etc.

[0067] The B motor PWM generation unit generates six complementary PWM signals to drive the power devices in inverter B, based on the B motor PWM reference with phase difference adjustment (i.e., its carrier start point has been offset by the aforementioned CNT_Diff) and the voltage vector command generated by the B motor's own control algorithm. Similarly, this unit also generates FOC trigger, current sampling trigger, and other signals synchronized with the B motor PWM.

[0068] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the PWM phase difference in an on-board dual electric drive system, characterized in that, include: The unit includes a rotor angle difference processing unit, a rotor angle difference-PWM reference phase difference lookup table unit, a PWM reference phase difference command slope control unit, a PWM reference phase difference control enable detection unit, a PI controller, a dual-motor PWM reference start point timestamp capture and phase difference calculation unit, a PWM reference phase difference setting unit, an A motor PWM wave generation unit, and a B motor PWM wave generation unit. The rotor angle difference processing unit is used to calculate the electrical angle phase difference Δθ between the two motors based on the electrical angle of the rotor position of motor A and the electrical angle of the rotor position of motor B. The PWM reference phase difference command slope control unit is used to control the PWM reference phase difference φ_Fbk from the value of the PWM reference phase difference φ_Fbk at the moment when the Enable signal output by the PWM reference phase difference control enable detection unit is enabled, and to control the PWM reference phase difference command reference φ_Ref at a certain slope. The control process obtains the PWM reference phase difference command φ_Cmd. The PWM reference phase difference control enable detection unit is used to detect the enable conditions of PWM reference phase difference control, including the PWM signal frequencies of the driving semiconductor module A and the driving semiconductor module B being the same, the rotor position decoding of the two motors being fault-free, and the speed of the two motors being the same. After comprehensive analysis, the enable signal Enable is output and anti-jitter processing is performed.

2. The method for controlling the PWM phase difference of an on-board dual electric drive system according to claim 1, characterized in that: The rotor angle difference-PWM reference phase difference lookup table unit is used to look up the PWM reference phase difference command reference φ_Ref based on the electrical angle phase difference between the two motors.

3. The method for controlling the PWM phase difference of an on-board dual electric drive system according to claim 2, characterized in that: By controlling the PWM reference phase difference of the two motors according to the PWM reference phase difference command φ_Ref, the ripple current generated by the DC capacitor in the dual drive system can be mutually canceled and the ripple current in the DC capacitor can be reduced. The rotor angle difference-PWM reference phase difference table can be obtained through theoretical calculation and bench verification or bench calibration.

4. The method for controlling the PWM phase difference of an on-board dual electric drive system according to claim 1, characterized in that: When the Enable signal output by the PWM reference phase difference control enable detection unit is disabled, the value of the PWM reference phase difference command φ_Cmd remains unchanged when Enable is detected.

5. The method for controlling the PWM phase difference of an on-board dual electric drive system according to claim 1, characterized in that: The PI controller is used to dynamically adjust the measured PWM reference phase difference φ_Fbk and PWM reference phase difference command φ_Cmd through the PI controller when the Enable signal output by the PWM reference phase difference control enable detection unit is enabled, and output the PWM register count value CNT_Diff of the PWM reference phase difference.

6. The method for controlling the PWM phase difference of an on-board dual electric drive system according to claim 5, characterized in that: When the Enable signal output by the PWM reference phase difference control enable detection unit is disabled, the PI controller performs deintegration and other related processing.

7. The method for controlling the PWM phase difference of an on-board dual electric drive system according to claim 1, characterized in that: The dual-motor PWM reference start point timestamp capture and phase difference calculation unit is used to capture the PWM reference start point timestamps of the two motors, and at the same time calculate the PWM reference phase difference φ_Fbk based on the switching cycle.

8. The method for controlling the PWM phase difference of an on-board dual electric drive system according to claim 1, characterized in that: The PWM reference phase difference setting unit is used to set the PWM reference phase difference PWM register count value CNT_Diff output by the PI controller to the PWM reference of motor B when the signal Enable output by the PWM reference phase difference control enable detection unit is enabled, so as to change the PWM reference phase difference between the two motors. Among them, the PWM reference phase of motor A does not need to be processed. When the Enable signal output by the PWM reference phase difference control enable detection unit is disabled, the PWM reference phase of motor B also does not need to be processed.

9. The method for controlling the PWM phase difference of an on-board dual electric drive system according to claim 1, characterized in that: The A motor PWM wave generation unit is used to control the PWM wave generation of the A motor based on the PWM reference of the A motor, including 6-channel PWM output, FOC trigger output, current sampling trigger output, etc.

10. The method for controlling the PWM phase difference of an on-board dual electric drive system according to claim 1, characterized in that: The B motor PWM wave generation unit is used to control the PWM wave generation of the B motor based on the PWM reference of the B motor after phase difference control, including 6-channel PWM output, FOC trigger output, current sampling trigger output, etc.

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