Power conversion system cooperative control method based on CAN bus

Abstract

The invention discloses a power conversion system cooperative control method based on a CAN bus, and relates to the technical field of power conversion system control, and the method comprises the steps: setting a master machine and a slave machine of a power conversion system based on a plurality of devices connected in parallel, and selecting a CAN communication bus to carry out the data communication between the master machine and the slave machine, the method comprises the following steps: accurately calculating the phase of the slave computer during actual wave transmission by using a timestamp counter CANTSC value latched by a message object timestamp register MOTS of a CAN module in the slave computer and used for receiving an angle signal time sent by a host computer and a timestamp counter CANTSC value of an actual wave transmission time of the slave computer, so as to determine a wave transmission angle; meanwhile, according to the received amplitude information sent by the host, the slave calculates the modulation ratio of final wave sending by combining bus power supply of the respective driving controller; and the slave outputs signals with the same amplitude, the same frequency and the same phase in each control period according to the modulation ratio and the wave sending angle determined by calculation, so that accurate cooperative control among a plurality of drivers in the parallel operation system is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of power conversion system control, and in particular to a CAN bus-based power conversion system collaborative control method. Background Art

[0002] With the rapid development of the industrial field, a single inverter power module or device is increasingly unable to meet the industry's high-power needs, and multiple devices in parallel have become the main means of expanding the capacity of energy storage power conversion systems. In order to achieve the stable operation of the parallel system, it is necessary to coordinate the control of each device to ensure that the real-time output voltage amplitude, phase and frequency of each device are the same, otherwise it will cause system circulation and lead to parallel failure. Similarly, for the control of multi-branch motors for large-capacity electric propulsion of marine equipment in the industrial field, it is necessary to control multiple groups of stator unit modules and their winding branches of the motor through multiple drivers. Coordinated control is required between multiple drivers to ensure output synchronization, otherwise the output frequency or phase will be different, causing the motor speed and electromagnetic torque to fluctuate violently, and the motor cannot operate stably. Therefore, stable and effective coordinated control is an important prerequisite for ensuring the stable operation of parallel systems in the industrial field.

[0003] Existing collaborative control can adopt a method of outputting multiple groups of PWM through the same control unit, but the number of PWM output by a control unit is limited. Taking DSP28379 as an example, it can only output 24 PWM at most, so the number of parallel connections is limited, which is not conducive to system expansion; in addition, a synchronous pulse signal can be generated through hardware circuits or software. Each parallel device captures the synchronization signal and adjusts its own phase to achieve synchronization, but this method requires additional hardware, and the time from receiving the pulse signal to the final output voltage cannot be guaranteed to be completely consistent, and its synchronization accuracy is poor. Summary of the invention

[0004] In order to solve the deficiencies of the above-mentioned prior art, the present invention provides a collaborative control method for a power conversion system based on a CAN bus, by setting a master-slave machine for the parallel system, the master machine and each slave machine communicate through the CAN bus, and the message object timestamp register MOTS of the CAN module in the slave machine latches the time when the angle signal sent by the master machine is received and the timestamp counter CANTSC value of the actual time when the slave machine transmits the wave, so as to accurately calculate the phase of the slave machine when it actually transmits the wave; in addition, according to the amplitude information sent by the master machine received by the slave machine, combined with the bus power supply of each drive controller, the modulation ratio of the final wave is calculated, so as to ensure that the output voltage amplitude of each slave machine is consistent; by controlling the phase and amplitude in each control cycle, the output voltage amplitude, phase and frequency of each slave machine are finally consistent, and accurate collaborative control between multiple drivers in the parallel system is realized.

[0005] In a first aspect, the present invention provides a collaborative control method for a power conversion system based on a CAN bus.

[0006] A CAN bus-based power conversion system collaborative control method, comprising:

[0007] Set up a master and slave machine of a power conversion system based on multiple devices in parallel, and select a CAN communication bus for data communication between the master and slave machines;

[0008] The host calculates the angle step value of each control cycle according to the wave voltage and the control frequency, and calculates the number of control cycles corresponding to the wave voltage cycle. When the number of control cycles is reached, the host sends an angle zero-crossing instruction to multiple slaves synchronously.

[0009] Each slave calculates and determines the phase angle of the actual transmission of the slave according to the timestamp counter CANTSC value of the CAN receiving buffer receiving the angle zero-crossing instruction latched in the respective MOTS register and the timestamp counter CANTSC value of the slave actually transmitting the wave;

[0010] Combined with the angle step value, determine the transmission angle of each slave in each control cycle;

[0011] The slave outputs signals of the same amplitude, frequency and phase in each control cycle according to the calculated modulation ratio and transmission angle to complete the coordinated control.

[0012] Further technical solutions, before allowing the wave to be launched, are carried out in advance, including:

[0013] Before the master starts, the master sends a shutdown command to each slave via broadcast;

[0014] After the host starts, it asks all slaves whether they are ready to send waves through broadcasting. The slaves return the wave-sending preparation status to the host. After all slaves are ready to send waves, the host sends a wave-sending permission command to the slaves through broadcasting.

[0015] A further technical solution is to calculate the phase angle when the slave actually transmits the wave, including:

[0016] For each slave, obtain the count value of the timestamp counter CANTSC at the moment when the CAN receiving buffer receives the angle zero-crossing instruction latched by the slave MOTS register, and read the count value of the slave timestamp counter CANTSC at the moment when the slave actually sends the wave;

[0017] The difference operation is performed based on the two count values ​​obtained to calculate the time period from when the slave receives the angle zero-crossing instruction sent by the host from the CAN receiving buffer to the actual wave transmission moment;

[0018] Combined with the time period from when the host sends data to when the slave CAN receiving buffer receives data, calculate and determine the precise delay time period from when the slave actually sends the wave to when the host sends the angle zero-crossing instruction;

[0019] According to the calculated precise delay time period, the phase angle of the slave device relative to the master device when the slave device actually transmits the wave is calculated.

[0020] A further technical solution is to determine the transmission angle of each control cycle by accumulating the phase angle and angle step value for each slave machine based on the actual transmission phase angle of the slave machine in the initial control cycle and the angle step value of each control cycle.

[0021] A further technical solution is that when the control cycle number is counted, the next control cycle is taken as the initial control cycle, and the angle of the host in the initial control cycle is reset to zero.

[0022] A further technical solution is that in each control cycle, the host calculates the amplitude of the phase voltage of the wave generator and sends the phase voltage amplitude once to all slaves via CAN; wherein, in the initial control cycle, the host sends the phase voltage amplitude and the angle zero-crossing instruction to each slave at the same time;

[0023] After receiving the phase voltage amplitude, each slave calculates the modulation ratio in combination with the detected DC bus voltage of the respective inverter.

[0024] According to a further technical solution, the power conversion system based on multiple devices in parallel adopts SPWM modulation.

[0025] According to a further technical solution, the host calculates the amplitude of the wave-generating phase voltage, including:

[0026] The line voltage output by multiple slaves in parallel is sampled through the ADC module, and the feedback phase voltage amplitude is calculated according to the line voltage;

[0027] The PI closed-loop control output is performed according to the set phase voltage amplitude and the feedback phase voltage amplitude, and the output value is limited;

[0028] The value after the limiting process is added to the set phase voltage amplitude to obtain the final wave phase voltage amplitude.

[0029] In a further technical solution, the calculation formula of the modulation ratio M is:

[0030]

[0031] In the above formula, U dc Represents the detected inverter DC bus voltage, V PAmp_S Indicates the phase voltage amplitude sent by the host and received by the slave. The calculation formula is: Where k is the ratio of the maximum detection voltage of the master and slave, k = V max_M / V max_S , V max_M The maximum detection voltage of the host is V max_S is the maximum detection voltage of the slave, is the set phase voltage amplitude, and PIout is the output value of the voltage closed-loop control.

[0032] A further technical solution is that the slave outputs signals with the same amplitude, frequency and phase in each control cycle according to the calculated modulation ratio and transmission angle to complete the coordinated control, including:

[0033] The slave calculates the modulation wave of SPWM transmission in each control cycle according to the modulation ratio and transmission angle determined by calculation;

[0034] The modulated wave is compared with the triangular carrier of the control chip for PWM output. After passing through the inverter, AC power with the same amplitude, frequency and phase is output to complete the coordinated control of the parallel system.

[0035] One or more of the above technical solutions have the following beneficial effects:

[0036] 1. The present invention provides a CAN bus-based power conversion system collaborative control method, which uses the message object timestamp register MOTS and the timestamp counter CANTSC of the CAN module in the slave machine without using the hardware synchronization signal to achieve more accurate phase synchronization. In which, the parallel system is set with a master and a slave machine, and the master machine communicates with each slave machine through the CAN bus. The message object timestamp register MOTS of the CAN module in the slave machine is used to latch the time when the angle signal sent by the master machine and the timestamp counter CANTSC value of the actual time when the slave machine actually sends the wave, and the phase of each slave machine when it actually sends the wave is accurately calculated, so as to achieve accurate phase synchronization, and the phase corresponding time error between the slave machines can be reduced to a few microseconds.

[0037] 2. In the present invention, the host sends an amplitude instruction to the slave in each control cycle. The slave calculates the modulation ratio of the final wave according to the amplitude information sent by the host and the bus power supply of each drive controller to ensure the output amplitude set by the host, that is, to ensure that the output voltage amplitude of each slave is consistent, thereby achieving higher-precision amplitude control.

[0038] 3. The present invention controls the phase and amplitude in each control cycle, and finally achieves consistency in the output voltage amplitude, phase and frequency of each slave, realizes precise coordinated control between multiple drivers in the parallel system, and can realize the parallel function of multiple slaves. It can be modularly configured according to power requirements to facilitate system expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0040] Figure 1 is a schematic diagram of phase synchronization control in an embodiment of the present invention;

[0041] Figure 2 A control block diagram of amplitude coordinated control in an embodiment of the present invention;

[0042] Figure 3 Schematic diagram of the master-slave cooperative control of the power conversion system based on the CAN bus in an embodiment of the present invention;

[0043] Figure 4 The flowchart of the host sending instructions to the slave in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] It should be noted that the following detailed descriptions are exemplary only, are intended to describe specific embodiments, are intended to provide further explanation of the present invention, and are not intended to limit exemplary embodiments according to the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0045] Embodiment 1

[0046] This embodiment provides a CAN bus-based power conversion system collaborative control method, which specifically includes the following steps:

[0047] Set up a master and slave machine of a power conversion system based on multiple devices in parallel, and select a CAN communication bus for data communication between the master and slave machines;

[0048] The host calculates the angle step value of each control cycle according to the wave voltage and the control frequency, and calculates the number of control cycles corresponding to the wave voltage cycle. When the number of control cycles is reached, the host sends an angle zero-crossing instruction to multiple slaves synchronously.

[0049] Each slave calculates and determines the phase angle of the actual transmission of the slave according to the timestamp counter CANTSC value of the CAN receiving buffer receiving the angle zero-crossing instruction latched in the respective MOTS register and the timestamp counter CANTSC value of the slave actually transmitting the wave;

[0050] Combined with the angle step value, determine the transmission angle of each slave in each control cycle;

[0051] The slave outputs signals of the same amplitude, frequency and phase in each control cycle according to the calculated modulation ratio and transmission angle to complete the coordinated control.

[0052] The above content provides a more detailed introduction to the CAN bus-based power conversion system collaborative control method proposed in this embodiment.

[0053] Step S0: Set up the master and slave machines of the power conversion system based on multiple devices in parallel, and select the CAN communication bus for data communication between the master and slave machines. Specifically, set up the master and slave machines of the system, and label the master and slave machines, with the master machine being marked as M and the multiple slave machines being marked as S in sequence. 1 ,S 2 ,…S N , where the host is used to calculate the amplitude of the wave and send the amplitude and angle zero crossing instructions to the slave, and the slave is used to output AC voltage according to the instructions sent by the host. In addition, a CAN communication bus with high safety and reliability is selected to realize data communication between the master and slave modules (i.e., the master and slave). In this embodiment, the host is denoted as M and the slave 1 is denoted as S 1 , slave 2 is denoted as S 2 Take this as an example for introduction.

[0054] Step S1, make preliminary preparations before allowing the wave to be sent, i.e., the preparation stage before allowing the wave to be sent. Before the host starts, it sends a shutdown command to each slave; after the host starts, it asks all slaves whether they are ready to send the wave through broadcasting, and the slaves return the accurate information of whether they are ready to send the wave to the host according to their own conditions. After all slaves are ready to send the wave, the host sends a command to allow the wave to be sent to the slaves through broadcasting.

[0055] After the above step S1, the master-slave cooperative control is performed. In this embodiment, the wave phase and amplitude are controlled in each control cycle, and finally the output voltage amplitude, phase and frequency of each slave are consistent, so as to realize the precise cooperative control between multiple drivers in the parallel system. First, the wave amplitude cooperative control in each control cycle is introduced.

[0056] Step S2, the host calculates the amplitude of the wave-generating phase voltage. Specifically, the host sets the phase voltage amplitude; the host samples the line voltage output by multiple slaves in parallel through the ADC module, and obtains the feedback phase voltage amplitude according to the line voltage calculation; the host performs PI closed-loop control output according to the set phase voltage amplitude and the feedback phase voltage amplitude, and performs amplitude limiting processing on the output value; the value after amplitude limiting processing is added to the set phase voltage amplitude as the final real amplitude of the wave-generating phase voltage; in addition, in each control cycle, the host sends the phase voltage amplitude to each slave once through CAN.

[0057] like Figure 2As shown, step S2.1, the host sets the phase voltage amplitude to

[0058] Step S2.2: The host uses the ADC module to sample the two line voltages V output by the slaves in parallel. ab and V bc , convert the two line voltages to the stationary coordinate system to obtain V α and V β , and calculate the output phase voltage amplitude V PAmp , the calculation formula is as follows:

[0059]

[0060] Step S2.3, calculate the output value of the voltage closed loop, and limit the output value. Taking the position PI closed loop control as an example, the calculation formula is as follows:

[0061]

[0062] In the above formula, PIout is the output value of the voltage closed loop, K p is the voltage loop proportional coefficient, K i is the voltage loop integration coefficient.

[0063] Step S2.4, calculate the phase voltage amplitude V used by the slave to actually generate the wave PAmp_S , the calculation formula is:

[0064]

[0065] In the above formula, k is the ratio of the maximum detection voltage of the master and slave.

[0066] Furthermore, let the maximum detection voltage of the host be V max_M , the maximum detection voltage of the slave is V max_S , then k = V max_M / V max_S , the above formula can be expressed as:

[0067]

[0068] Step S2.5: In each control cycle, the host sends the phase voltage amplitude to each slave once via CAN.

[0069] Step S3: The slave calculates the actual modulation ratio for wave generation. Specifically, the slave receives the phase voltage amplitude of the wave generation from the master in each control cycle, and calculates the modulation ratio in combination with the DC bus voltage of each inverter detected by the slave itself.

[0070] In order to adapt to parallel control, the power conversion system based on multiple devices in parallel in this embodiment adopts SPWM modulation. When the modulation ratio is 1, the maximum output phase voltage amplitude is U dc / 2, so the slave receives the phase voltage amplitude V sent by the host. PAmp_S And the detected inverter DC bus voltage U dc , the modulation ratio M can be calculated, and its calculation formula is:

[0071]

[0072] By calculating through the above formula, N (in this embodiment, N=2) slaves each calculate the modulation ratio M in real time according to their actual bus voltage value. 1 ,M 2 …M N .

[0073] Secondly, the coordinated control of the transmission phase in each control cycle is introduced.

[0074] Step S4, determination of the host angle zero-crossing instruction. Specifically, the host calculates the angle step value of each control cycle according to the wave voltage frequency and the wave control frequency, and calculates the number of control cycles corresponding to one electrical cycle of the wave voltage. Whenever the number of control cycles is counted, the angle is reset once, and at the same time, the host synchronously sends the angle zero-crossing instruction to multiple slaves.

[0075] Step S4.1, taking the frequency of the wave voltage as f w , the wave control frequency is f c For example, the period of the wave voltage is calculated to be T w =1 / f w s, the control period is T c =1 / f c s, then each voltage cycle corresponds to n c =T w / T c The angle step value of each control cycle is θ step for Among them, the wave voltage frequency and the wave control frequency are both set manually. The wave voltage frequency is set according to the output voltage of the power conversion system, and the wave control frequency setting is consistent with the actual PWM frequency of the slave.

[0076] In this embodiment, taking the wave voltage frequency of 50 Hz and the wave control frequency of 2 kHz as an example, it is calculated that the period of the wave voltage is 20 ms and the control period is 500 us. Each voltage period corresponds to 40 control periods, and the angle step value of each control period is 360° / 40=9°.

[0077] Step S4.2: The host sets a count value Cnt. The count value increases by one in each control cycle, and the corresponding angle increases by θ. step , after each addition of n c After each step angle, Cnt restarts counting and resets the angle to zero. In this embodiment, the count value of each control cycle is increased by one, and the corresponding angle is increased by 9 degrees. After each 40 step angles are added, Cnt restarts counting and resets the angle to zero.

[0078] Step S4.3, the host sends a host zero-crossing instruction to the slave via CAN in the current control cycle corresponding to the angle clearing. Specifically, when the number of control cycles is counted, the next control cycle is taken as the initial control cycle, and the angle of the host in the initial control cycle is cleared, that is, the current control cycle corresponding to the angle clearing is the initial control cycle. In addition, in the initial control cycle, the host sends the phase voltage amplitude and angle zero-crossing instructions to each slave at the same time.

[0079] Step S5: The slave calculates the actual phase angle when transmitting the wave. Figure 1 As shown, each slave calculates and determines the phase angle of the actual transmission of the slave according to the timestamp counter CANTSC value of the CAN receiving buffer receiving angle zero-crossing instruction latched in its respective MOTS register and the timestamp counter CANTSC value of the slave actually transmitting. Based on the calculated phase angle, phase coordinated control can be achieved.

[0080] Specifically, the time when the CAN receiving buffer of each slave receives the zero-crossing signal (i.e., the angle zero-crossing instruction) sent by the master can be considered to be consistent, which is recorded as δ 0 For each slave, the time from when the CAN receiving buffer receives the zero-crossing signal sent by the host to the actual wave transmission time can be obtained by subtracting the timestamp counter CANTSC value at the time when the CAN receiving buffer receives the angle zero-crossing instruction latched in the respective MOTS register from the timestamp counter CANTSC value at the actual wave transmission time of the slave, and the time can be obtained by making a difference, such as Figure 3 As shown, this period of time of slave 1 is recorded as δ t1 , the time of slave 2 is recorded as δ t2 , this time of slave N is recorded as δ tN ; Add the above two time periods together, that is, the time when the CAN receiving buffer of each slave receives the zero-crossing signal sent by the host and the time obtained by the above difference, and you can get the time when each slave actually transmits the wave from the host to zero; then, convert the time into an angle, and accurately calculate the phase angle when the slave actually transmits the wave. On this basis, each slave performs forced phase correction according to the received zero-crossing signal, and then accumulates the angle according to each control cycle step to achieve the purpose of phase synchronization of each slave.

[0081] Step S5.1: The time when each slave CAN buffer successfully receives the CAN data sent by the host can be considered to be roughly the same. The time from the host sending data to the slave buffer receiving the data is recorded as δ 0 Among them, when the CAN baud rate is Sbps, according to the set data protocol, assuming that the number of bytes sent is n data , with a value of 0-8, when it is a standard frame, then δ 0 Approximately (44+n data *8) / S seconds; when it is an extended frame, δ 0 Approximately (64+n data *8) / S seconds; however, depending on the data, there may be bit stuffing, and the specific time can be obtained through testing. In this embodiment, taking the CAN baud rate of 500kbps and the standard data frame sending 6 bytes of data as an example, the actual measured δ 0 It is about 172us.

[0082] Step S5.2, for each slave, obtain the timestamp counter CANTSC count value at the moment when the CAN receiving buffer receives the angle zero-crossing instruction latched by the slave MOTS register. Specifically, the MOTS register of each slave will latch the CANTSC count value after the CAN buffer receives the data. Among them, the value of the CANTSC counter latched by the MOTS of slave 1 is recorded as t 1_MOTS , the value of the CANTSC counter latched by the MOTS of slave 2 is recorded as t 2_MOTS , the value of the CANTSC counter latched by the MOTS of slave N is recorded as t N_MOTS .

[0083] Furthermore, since the time when the CAN receiving buffer of each slave receives the data sent by the host is the same, the latching time is not much different. However, since the power-on time of each slave is different, that is, the time when CANTSC starts timing from 0 is different, even if it is latched at the same time, the CANTSC value of MOTS latched by MOTS will be quite different. Therefore, the latched value cannot be directly used for processing, and subsequent operations are required to calculate a more accurate wave transmission phase.

[0084] Step S5.3: For each slave, read the count value of the slave timestamp counter CANTSC at the actual transmission time of the slave. Specifically, each slave reads the value of the CANTSC register at the transmission point, and the value of the CANTSC register read by slave 1 is recorded as t 1_TSC , the value of the CANTSC register read by slave 2 is recorded as t 2_TSC , the value of the CANTSC register read by slave N is recorded as t N_TSC .

[0085] Step S5.4: Based on the two time count values ​​obtained in the above steps S5.2 and S5.3, the time period from when the slave receives the angle zero-crossing instruction sent by the host from the CAN receiving buffer to when the slave actually sends the wave is obtained by performing a difference calculation. t1 , slave 2 is denoted as δ t2 , slave N is denoted as δ tN , the calculation formula can be expressed as:

[0086]

[0087] Step S5.5: According to the two time periods obtained in the above steps S5.1 and S5.4, calculate and determine the precise delay time period (in us) from the actual transmission time of the slave to the time when the master sends the angle zero-crossing instruction. 1 , slave 2 is denoted as δ 2 , slave N is denoted as δ N , the calculation formula can be expressed as:

[0088]

[0089] Step S5.6: According to the calculated accurate delay time period, the phase angle of the slave relative to the master when the slave actually transmits the wave is calculated. The calculation formula is:

[0090]

[0091] In this embodiment, the phase angles of slave 1 and slave 2 relative to the host when actually transmitting are calculated as:

[0092] θ 1 =δ 1 / 500*9

[0093] θ 2 =δ 2 / 500*9

[0094] Step S5.7: Each slave performs forced phase correction according to the received zero-crossing signal. That is, after slave 1 receives the synchronization signal sent by the host, the transmission angle is θ 1 , the transmission angle of slave 2 is θ 2 , the transmission angle of slave N is θ N .

[0095] Step S5.8: For each slave, based on the actual phase angle of the slave during the initial control cycle, the angle step value θ of each control cycle is calculated. step , phase angle and angle step value θ are performed for each control cycle stepThe accumulation of is used to determine the wave transmission angle of each control cycle. The wave transmission at this angle can improve the accuracy of slave synchronization and achieve the purpose of phase synchronization of each slave.

[0096] Step S6: The slave outputs a signal with the same amplitude, frequency and phase in each control cycle according to the calculated modulation ratio and wave transmission angle to complete the coordinated control. Specifically, the slave can calculate the modulation wave of the SPWM wave in each control cycle according to the above-calculated modulation ratio and wave transmission angle, compare the modulation wave with the triangular carrier of the control chip, and use it for PWM output. After passing through the inverter, the same amplitude, frequency and phase AC output is achieved, and the coordinated control of the parallel system is realized.

[0097] The above-mentioned CAN bus-based power conversion system cooperative control method proposed in this embodiment realizes the cooperative control of the parallel system by sending instructions from the host to the slave, and the master and slave execute the above-mentioned operation process. Figure 4 As shown, during the whole process, the host runs and sends a phase voltage amplitude to each slave through CAN in each control cycle. When the number of control cycles corresponding to the electrical cycle is counted, after the slave feedback is ready to send waves, the host sends synchronization + amplitude to each slave through CAN, that is, the phase voltage amplitude and angle zero-crossing instructions are sent to each slave at the same time. The slave calculates and determines the modulation ratio and the wave transmission angle according to the above method, and outputs signals with the same amplitude, frequency and phase in each control cycle to complete the coordinated control.

[0098] Those skilled in the art should understand that the above steps of the present invention can be implemented by a general-purpose computer device, or alternatively, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0099] The above description is only a preferred embodiment of the present invention. Although the specific implementation mode of the present invention is described in conjunction with the accompanying drawings, it is not a limitation of the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the protection scope of the present invention.

Claims

1. A CAN bus-based power conversion system collaborative control method, characterized in that: include: Set up a master and slave machine of a power conversion system based on multiple devices in parallel, and select a CAN communication bus for data communication between the master and slave machines; The host calculates the angle step value of each control cycle according to the wave voltage and the control frequency, and calculates the number of control cycles corresponding to the wave voltage cycle. When the number of control cycles is reached, the host sends an angle zero-crossing instruction to multiple slaves synchronously. Each slave calculates and determines the phase angle of the actual transmission of the slave according to the timestamp counter CANTSC value of the CAN receiving buffer receiving the angle zero-crossing instruction latched in the respective MOTS register and the timestamp counter CANTSC value of the slave actually transmitting the wave; Combined with the angle step value, determine the transmission angle of each slave in each control cycle; The slave outputs signals of the same amplitude, frequency and phase in each control cycle according to the calculated modulation ratio and transmission angle to complete the coordinated control.

2. A CAN bus-based power conversion system collaborative control method as claimed in claim 1, characterized in that: Before the wave is allowed to be sent, preliminary preparations are made, including: Before the master starts, the master sends a shutdown command to each slave via broadcast; After the host starts, it asks all slaves whether they are ready to send waves through broadcasting. The slaves return the wave-sending preparation status to the host. After all slaves are ready to send waves, the host sends a wave-sending permission command to the slaves through broadcasting.

3. The CAN bus-based power conversion system collaborative control method according to claim 1, characterized in that: The calculation of the phase angle when the slave actually transmits the wave includes: For each slave, obtain the count value of the timestamp counter CANTSC at the moment when the CAN receiving buffer receives the angle zero-crossing instruction latched by the slave MOTS register, and read the count value of the slave timestamp counter CANTSC at the moment when the slave actually sends the wave; The difference operation is performed based on the two count values ​​obtained to calculate the time period from when the slave receives the angle zero-crossing instruction sent by the host from the CAN receiving buffer to the actual wave transmission moment; Combined with the time period from when the host sends data to when the slave CAN receiving buffer receives data, calculate and determine the precise delay time period from when the slave actually sends the wave to when the host sends the angle zero-crossing instruction; According to the calculated precise delay time period, the phase angle of the slave device relative to the master device when the slave device actually transmits the wave is calculated.

4. The CAN bus-based power conversion system collaborative control method according to claim 1, characterized in that: For each slave, based on the actual phase angle of the slave during the initial control cycle, and according to the angle step value of each control cycle, the phase angle and the angle step value are accumulated for each control cycle to determine the transmission angle of each control cycle.

5. The CAN bus-based power conversion system collaborative control method according to claim 1, characterized in that: When the control cycle number is counted, the next control cycle is taken as the initial control cycle, and the angle of the host in the initial control cycle is reset to zero.

6. The CAN bus-based power conversion system cooperative control method according to claim 1, characterized in that: In each control cycle, the host calculates the amplitude of the phase voltage of the wave generator and sends the phase voltage amplitude to all slaves via CAN. In the initial control cycle, the host sends the phase voltage amplitude and the angle zero-crossing instruction to each slave at the same time. After receiving the phase voltage amplitude, each slave calculates the modulation ratio in combination with the detected DC bus voltage of the respective inverter.

7. A CAN bus-based power conversion system cooperative control method as claimed in claim 6, characterized in that: The power conversion system based on multiple devices connected in parallel adopts SPWM modulation.

8. The CAN bus-based power conversion system cooperative control method according to claim 6, characterized in that: The host calculates the amplitude of the wave-generating phase voltage, including: The line voltage output by multiple slaves in parallel is sampled through the ADC module, and the feedback phase voltage amplitude is calculated according to the line voltage; The PI closed-loop control output is performed according to the set phase voltage amplitude and the feedback phase voltage amplitude, and the output value is limited; The value after the limiting process is added to the set phase voltage amplitude to obtain the final wave phase voltage amplitude.

9. A CAN bus-based power conversion system cooperative control method as claimed in claim 8, characterized in that: The calculation formula of the modulation ratio M is: In the above formula, U dc Represents the detected inverter DC bus voltage, V PAmp_S Indicates the phase voltage amplitude sent by the host and received by the slave. The calculation formula is: Where k is the ratio of the maximum detection voltage of the master and slave, k = V max_M / V max_S , V max_M The maximum detection voltage of the host is V max_S is the maximum detection voltage of the slave, is the set phase voltage amplitude, and PIout is the output value of the voltage closed-loop control.

10. The CAN bus-based power conversion system cooperative control method according to claim 1, characterized in that: The slave outputs signals with the same amplitude, frequency and phase in each control cycle according to the calculated modulation ratio and transmission angle to complete the coordinated control, including: The slave calculates the modulation wave of SPWM transmission in each control cycle according to the modulation ratio and transmission angle determined by calculation; The modulated wave is compared with the triangular carrier of the control chip for PWM output. After passing through the inverter, AC power with the same amplitude, frequency and phase is output to complete the coordinated control of the parallel system.

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