Bus side capacitance determination method and device, equipment and storage medium

Abstract

The invention discloses a bus side capacitance determination method and device, equipment and a storage medium, and the method comprises the steps: transmitting a voltage rising instruction to a frequency converter, so as to enable the bus voltage to rise from an initial bus voltage value; the initial bus voltage value is a voltage value generated by counter electromotive force on the motor side when the frequency converter does not start control; determining at least two bus voltage values and corresponding moments within the time period when the bus voltage rises to the target bus voltage value; and calculating the capacitance value of the bus side capacitor according to the current value corresponding to the voltage rising instruction, the at least two bus voltage values and the corresponding moments. According to the invention, automatic identification of the bus-side capacitor without shutdown and external equipment can be realized, continuous operation of the system is guaranteed, and the maintenance cost is reduced.

Description

Technical Field

[0001] This application relates to the field of power electronics, and in particular to a method, apparatus, device and storage medium for determining bus-side capacitance. Background Technology

[0002] With the development of power electronics technology, DC power distribution electric propulsion systems are widely used in various types of ships due to their advantages in energy efficiency, robustness, and integration flexibility. In DC power distribution electric propulsion systems, the control performance of the DC bus voltage is highly dependent on the capacitance value of the bus-side capacitor. Currently, the capacitance value of the bus-side capacitor is mostly detected offline. This method requires system shutdown and relies on external detection equipment, affecting continuous system operation and increasing maintenance costs.

[0003] Therefore, how to provide a solution to the above-mentioned technical problems is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this application is to provide a method, apparatus, device, and storage medium for determining bus-side capacitance, which can achieve automatic identification of bus-side capacitance without shutdown or external equipment, ensuring continuous system operation and reducing maintenance costs.

[0005] To address the aforementioned technical problems, this application provides a method for determining bus-side capacitance, comprising:

[0006] A voltage boost command is issued to the frequency converter to cause the bus voltage to rise from the initial bus voltage value; the initial bus voltage value is the voltage value generated by the back electromotive force on the motor side when the frequency converter is not started.

[0007] Within the time period during which the bus voltage rises to the target bus voltage value, at least two bus voltage values ​​and their corresponding times are determined;

[0008] The capacitance value of the bus-side capacitor is calculated based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time.

[0009] Optionally, the voltage boost command is a current-type control command;

[0010] Sending voltage boost commands to the frequency converter, including:

[0011] A DC current reference value is injected into the frequency converter to cause the bus voltage to rise from the initial bus voltage value.

[0012] Optionally, the target bus voltage value is a preset voltage safety limit.

[0013] During the time period when the bus voltage rises to the target bus voltage value, at least two bus voltage values ​​and their corresponding times are determined, including:

[0014] Determine the first moment at which the DC current reference value is injected;

[0015] Determine the second moment when the bus voltage rises to the first bus voltage value;

[0016] Determine the third moment when the bus voltage rises to the preset voltage safety limit;

[0017] The second time is later than the first time, the third time is later than the second time, and the first bus voltage value is less than the preset voltage safety limit.

[0018] Optionally, the current value corresponding to the voltage boost command is the DC current reference value;

[0019] Based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time, calculate the capacitance value of the bus-side capacitor, including:

[0020] Determine a first time difference between the first time point and the second time point, and a second time difference between the second time point and the third time point;

[0021] The capacitance value of the bus-side capacitor is calculated using the DC current reference value, the first time difference, the second time difference, the initial bus voltage value, the first bus voltage value, and the preset voltage safety limit.

[0022] Optionally, the voltage boost command is a voltage-type control command;

[0023] Sending voltage boost commands to the frequency converter, including:

[0024] A voltage boost command is sent to the frequency converter. The voltage boost command is used to set the target bus voltage value and control the bus voltage to rise from the initial bus voltage value to the target bus voltage value at a preset slope.

[0025] Optionally, during the time period when the bus voltage rises to the target bus voltage value, at least two bus voltage values ​​and their corresponding times are determined, including:

[0026] Determine the fourth moment when the voltage boost command is issued to the frequency converter;

[0027] Determine the fifth moment when the bus voltage rises to the second bus voltage value;

[0028] Determine the sixth moment when the bus voltage rises to the target bus voltage value;

[0029] The fifth time point is later than the fourth time point, the sixth time point is later than the fifth time point, and the second bus voltage value is less than the target bus voltage value.

[0030] Optionally, the current value corresponding to the voltage boost command is the average current value flowing through the DC bus during the time period.

[0031] Based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time, calculate the capacitance value of the bus-side capacitor, including:

[0032] Determine the third time difference between the fourth and fifth time points, and the fourth time difference between the fifth and sixth time points;

[0033] The capacitance value of the bus-side capacitor is calculated using the average current value, the third time difference, the fourth time difference, the initial bus voltage value, the second bus voltage value, and the target bus voltage value.

[0034] This application also provides a bus-side capacitance determination device, comprising:

[0035] The control module is used to send a voltage boost command to the frequency converter so that the bus voltage rises from the initial bus voltage value; the initial bus voltage value is the voltage value generated by the back electromotive force on the motor side when the frequency converter is not started.

[0036] The first determining module is used to determine at least two bus voltage values ​​and their corresponding times during the time period in which the bus voltage rises to the target bus voltage value.

[0037] The calculation module is used to calculate the capacitance value of the bus-side capacitor based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time.

[0038] This application also provides an electronic device, including:

[0039] Memory, used to store computer programs;

[0040] A processor, configured to execute the computer program to implement the steps of the bus-side capacitance determination method as described in any of the preceding descriptions.

[0041] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the bus-side capacitance determination method as described in any of the above claims.

[0042] This application utilizes the back electromotive force naturally generated when the motor rotates in the system to establish the initial voltage conditions required for testing, eliminating the need for an external signal source or power supply. By issuing a voltage rise command to the frequency converter, voltage and time sampling is completed during the controlled rise of the bus voltage. There is no need to shut down the system or remove the capacitor. Finally, based on the current value corresponding to the command and the collected voltage and time data, the capacitance value of the bus-side capacitor is calculated online. This achieves online self-diagnosis without shutting down the system or connecting external equipment, ensuring continuous system operation and reducing maintenance costs. Attached Figure Description

[0043] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A schematic diagram of the control structure for a shaft-driven generator operating mode provided in this application;

[0045] Figure 2 A schematic diagram of a DC bus control loop in shaft-driven generator mode provided in this application;

[0046] Figure 3 The present application provides a method for when the DC side current is... When kept constant, the voltage on the capacitor side Waveform curve;

[0047] Figure 4 A flowchart illustrating the steps of a method for determining bus-side capacitance provided in this application;

[0048] Figure 5a This is a schematic diagram of a current-mode control structure provided in this application;

[0049] Figure 5b This is a schematic diagram of a voltage-type control structure provided in this application;

[0050] Figure 6 This is a schematic diagram of the structure of a bus-side capacitance determination device provided in this application. Detailed Implementation

[0051] The core of this application is to provide a method, apparatus, device, and storage medium for determining bus-side capacitance, which can achieve automatic identification of bus-side capacitance without shutdown or external equipment, ensuring continuous system operation and reducing maintenance costs.

[0052] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0053] First, it should be noted that the shaft generator system effectively supplements the propulsion power of the main thruster or DC power distribution based on the shaft generator operating mode (PTO) and shaft motor operating mode (PTI) and control commands, thereby improving propulsion power or main engine power utilization. The control structure for the shaft generator operating mode (PTO) is as follows: Figure 1 As shown, the main propulsion machine acts as the prime mover, driving the permanent magnet synchronous motor to rotate. The rotor inside the motor is a permanent magnet. According to the law of electromagnetic induction, an electromotive force is induced on the input side of the motor, realizing the conversion of electrical energy.

[0054] DC bus control loop in shaft-driven generator mode, such as Figure 2 As shown. The control loop consists of a voltage control outer loop and a current control inner loop, where the current inner loop can be equivalent to a loop with a cutoff frequency of... The first-order control system, therefore the open-loop transfer function of the voltage closed-loop control system is as follows:

[0055] , formula (1.1);

[0056] , The proportional and integral coefficients of the PI controller in the bus voltage loop are given, and K is the conversion factor (constant) between the motor torque current and the DC current of the capacitor. The bandwidth of the above system is... Select the PI controller cutoff frequency With current loop bandwidth Between, where the current loop can be below The frequency is modeled as unity gain, and the PI controller element of the voltage control loop is in... The integral term can be approximately ignored; the above open-loop transfer function has a bandwidth of... It can be simplified to:

[0057] , formula (1.2);

[0058] According to the definition of bandwidth, there exists Therefore, the proportional gain of the voltage loop :

[0059] , formula (1.3);

[0060] Damping ratio of a second-order system Then it exists:

[0061] , formula (1.4);

[0062] Therefore, in order to determine the proportional and integral coefficients of the voltage loop PI controller, improve the performance of the control system, and meet the system's response requirements, it is necessary to identify the bus-side capacitor.

[0063] The following section introduces the mathematical relationship between the capacitance value of the bus-side capacitor and the voltage and current:

[0064] For the DC bus capacitor, neglecting line impedance and disconnecting it from the load, it can be equivalent to an integrator, as follows:

[0065] , formula (1.5);

[0066] When DC side current When kept constant, the voltage on the capacitor side The waveform curve is as follows Figure 3 As shown, the formula for calculating its capacity value is as follows:

[0067] , formula (1.6).

[0068] The relationship between the torque current on the permanent magnet synchronous motor side and the DC current is described below:

[0069] The voltage equation of a permanent magnet synchronous motor in a synchronous rotating coordinate system is: where,

[0070] , formula (1.7);

[0071] in, For the direct-axis inductance of a permanent magnet synchronous motor, For the quadrature axis inductance of a permanent magnet synchronous motor, Let be the permanent magnet flux linkage of the permanent magnet synchronous motor. In the synchronous rotating coordinate system, the power calculation expressions for the motor side and the DC side are:

[0072] , formula (1.8);

[0073] , formula (1.9);

[0074] Therefore, in order to ensure the DC side current Keeping constant, the torque current given to the permanent magnet synchronous motor side has the following relationship:

[0075] , formula (1.10);

[0076] use The control method ignores the effects of impedance and transients, thus obtaining the commanded torque current:

[0077] , formula (1.11).

[0078] The relationship between the three-phase current on the AC side and the current on the DC side is described below:

[0079] The instantaneous power on the AC side and the DC side has the relationship shown in formula (1.7):

[0080] , formula (1.12);

[0081] Phase voltage The formula for calculating the average value is shown in formula (1.8), where Let be the duty cycle of the three-phase bridge arm, where:

[0082] , formula (1.13);

[0083] The simplified DC-side current after average value modeling is obtained : , formula (1.14);

[0084] in, , , This is the normalized three-phase modulated wave.

[0085] Please refer to Figure 4 This application provides a method for determining bus-side capacitance, including:

[0086] S101: Sends a voltage boost command to the frequency converter to make the bus voltage rise from the initial bus voltage value; the initial bus voltage value is the voltage value generated by the back electromotive force on the motor side when the frequency converter is not started.

[0087] Before issuing the voltage boost command to the frequency converter in this step, the prime mover is controlled to run, and the controlled motor (which can be a permanent magnet synchronous motor) runs at an electrical angular velocity of... Before initiating bus-side capacitor identification, first provide... , Less than or equal to the maximum withstand voltage value on the DC bus side of the frequency converter It is understandable that when the operating frequency of the permanent magnet synchronous motor is... At that time, the reverse electromotive force induced on its incoming line side is approximately When the current is naturally rectified to the bus side by the three-phase bridge inverter circuit inside the frequency converter, the bus voltage is approximately .like Figure 3 time period As shown, since the controller is not running, the bus voltage remains at Record the current bus voltage value in the vicinity. , as the initial bus voltage value.

[0088] exist At any given time, a voltage boost command is sent to the frequency converter. In this embodiment, the voltage boost command can be a current-type control command or a voltage-type control command. This voltage boost command is used to control the bus voltage from the initial bus voltage value. It has begun to rise.

[0089] This embodiment utilizes the back electromotive force naturally generated during motor operation as the initial voltage reference for testing, and issues a voltage boost command based on this, achieving autonomous construction of test conditions and precise triggering of excitation. This avoids dependence on external test power supplies or dedicated signal generators, while ensuring that the identification process of bus-side capacitors can be started directly without shutting down the system.

[0090] S102: During the time period when the bus voltage rises to the target bus voltage value, determine at least two bus voltage values ​​and their corresponding times.

[0091] In this embodiment, the target bus voltage value is a preset voltage value. During the entire time span from the initial bus voltage value to the target bus voltage value, the voltage detection unit of the frequency converter samples the bus voltage at at least two different time points and records the instantaneous bus voltage value corresponding to each sampling moment. Specifically, the determined at least two bus voltage values ​​and their corresponding times include: acquiring a first bus voltage value at a first moment during the voltage rise process; acquiring a second bus voltage value at a second moment during the voltage rise process; wherein the first moment and the second moment are different, and the second bus voltage value is higher than the first bus voltage value.

[0092] By directly collecting the instantaneous voltage values ​​at at least two different time points and their corresponding times during the dynamic rise of the bus voltage, key, paired voltage-time data are provided for subsequent calculations.

[0093] S103: Calculate the capacitance value of the bus-side capacitor based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time.

[0094] In this embodiment, the corresponding current value differs depending on whether the voltage boost command is a current-type control command or a voltage-type control command. This embodiment first calculates the voltage difference and time difference based on at least two bus voltage values ​​determined in S102 and their corresponding times. Then, by substituting the voltage difference, time difference, and current value into the capacitance calculation formula, the capacitance value on the bus side can be calculated. The voltage difference is the difference between the higher and lower of the two bus voltage values, and the time difference is the difference in the times corresponding to the acquisition of these two voltage values.

[0095] As can be seen, this embodiment utilizes the back electromotive force naturally generated when the motor rotates in the system to establish the initial voltage conditions required for testing, eliminating the need for an external signal source or power supply. By issuing a voltage rise command to the frequency converter, voltage and time sampling is completed during the controlled rise of the bus voltage. There is no need to shut down the system or remove the capacitor. Finally, based on the current value corresponding to the command and the collected voltage and time data, the capacitance value of the bus-side capacitor is calculated online. This achieves self-diagnosis without shutting down the system or connecting external equipment, ensuring continuous system operation and reducing maintenance costs.

[0096] Furthermore, according to formula (1.11), this embodiment provides as follows: Figure 5a The control structure shown is as follows. The DC side current is an input for torque current calculation, and its control loop is a current-type control. For example... Figure 3 As shown, during the capacitance identification process on the bus side, the DC bus voltage continuously increases. Therefore, to avoid overvoltage, an upper limit is imposed on the DC bus voltage. According to formula (1.14), the following is provided: Figure 5b The control structure is shown. To ensure a fixed DC current value, the bus voltage reference must pass through a ramp generator, whose control loop is a voltage-type control. Since the exact value of the capacitor is currently undetermined, the proportional and integral parameters of the PI controller need to be roughly calibrated using the inverter's factory settings, with the capacitance range based on the inverter's rated current. Make an estimate.

[0097] The implementation steps for identifying current-type controlled capacitors and voltage-type controlled capacitors are explained below.

[0098] In one exemplary embodiment, the voltage boost command is a current-type control command;

[0099] Sending voltage boost commands to the frequency converter, including:

[0100] Inject a DC current reference value into the frequency converter so that the bus voltage starts to rise from the initial bus voltage value.

[0101] In this embodiment, when the voltage boost command is a current-type control command, the voltage boost command is sent to the frequency converter, that is, in A DC current reference value is continuously injected into the current loop of the frequency converter. The DC current reference value charges the bus-side capacitor, and this DC current reference value is constant, thereby causing the bus voltage to rise from the initial bus voltage value.

[0102] This embodiment uses current-type control commands to achieve voltage boosting. By injecting a constant DC current to charge the capacitor, the bus voltage exhibits a linear upward trajectory. This method is straightforward and precise, not only avoiding potential overshoot or oscillations during voltage rise, but also greatly simplifying the acquisition of current parameters in subsequent capacitor calculation formulas (directly using set values) due to the constant charging current, thus improving the certainty and calculation accuracy of the entire identification process.

[0103] In one exemplary embodiment, the method for determining the bus-side capacitance before injecting a DC current reference value into the frequency converter further includes:

[0104] Determine the first rated current of the motor;

[0105] Determine the second rated current of the frequency converter;

[0106] The DC current reference value is determined based on the first rated current and the second rated current.

[0107] In this embodiment, the constant DC current reference value is selected according to the following formula:

[0108] , formula (1.15);

[0109] in, The first rated current of the motor, This is the second rated current of the frequency converter, which can be obtained from the nameplate. The limitation specified by formula (1.15) ensures that the equivalent current referred to the motor side during capacitor charging does not exceed the rated value.

[0110] By introducing a step to determine the DC current reference value based on the rated current, this embodiment ensures that the capacitor identification process is conducted within electrical safety boundaries. Utilizing the most critical nameplate parameters (rated current) of the motor and inverter already present in the system as a safety benchmark eliminates the need for setting complex safety thresholds or conducting on-site testing, simplifying the parameter tuning process for engineering implementation. Selecting the smaller of the two values ​​as the current reference simultaneously protects the motor windings and inverter power devices from overcurrent risks caused by excessive identification current, ensuring equipment safety and operational reliability during the online identification process.

[0111] In one exemplary embodiment, the target bus voltage value is a preset voltage safety limit.

[0112] During the time period when the bus voltage rises to the target bus voltage value, at least two bus voltage values ​​and their corresponding times are determined, including:

[0113] The first moment to determine the reference value of the injected DC current;

[0114] Determine the second moment when the bus voltage rises to the value of the first bus voltage;

[0115] Determine the third moment when the bus voltage rises to the preset voltage safety limit;

[0116] The second time point is later than the first time point, the third time point is later than the second time point, and the voltage value of the first bus is less than the preset voltage safety limit.

[0117] In this embodiment, at the first moment Set DC current reference value The bus voltage begins to rise. During the rise, the bus voltage is recorded as it rises to the first bus voltage value. The second moment of time And the bus voltage rises to the preset voltage safety limit. (i.e. The third moment , refer to Figure 3 As shown, when the bus voltage rises to the preset voltage safety limit, this embodiment will activate the third time step. Set DC current reference value Reset to 0 to limit the bus voltage so that it does not exceed [the limit]. .

[0118] In constant current Under charging conditions, the bus voltage is to The interval increases linearly, and a midpoint within this linear segment is precisely selected. voltage and endpoint The voltage and its corresponding time can be used to obtain highly reliable voltage difference values. Time difference This provides a precise data foundation for subsequent capacitance calculations, ensuring accurate identification.

[0119] In one exemplary embodiment, the current value corresponding to the voltage boost command is a DC current reference value;

[0120] Based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time, calculate the capacitance value of the bus-side capacitor, including:

[0121] Determine the first time difference between the first and second moments, and the second time difference between the second and third moments;

[0122] The capacitance value of the bus-side capacitor is calculated using the DC current reference value, the first time difference, the second time difference, the initial bus voltage value, the first bus voltage value, and the preset voltage safety limit.

[0123] In this embodiment, the first time difference is first calculated. and the second time difference Then, the capacitance value of the current-mode control structure is obtained according to the following formula:

[0124] , formula (1.16).

[0125] In this embodiment, no complex segmented calculations or curve fitting are required. The calculation can be completed directly using the voltage and time data of the starting and ending points, as well as the known charging current. This reduces the computational burden on the controller and improves the real-time performance and reliability of the identification process.

[0126] In one exemplary embodiment, the voltage boost command is a voltage-type control command;

[0127] Sending voltage boost commands to the frequency converter, including:

[0128] A voltage boost command is sent to the frequency converter. The voltage boost command is used to set the target bus voltage value and control the bus voltage to rise from the initial bus voltage value to the target bus voltage value at a preset slope.

[0129] In this embodiment, when the voltage boost command is a voltage-type control command, the process of issuing the voltage boost command to the frequency converter includes: in Set the target bus voltage value at all times And control the bus voltage to rise at a fixed slope due to the ramp generator.

[0130] This embodiment achieves precise and smooth control of the bus voltage rise process. By using a fixed slope, it ensures the linearity and predictability of voltage changes, avoiding the impact that voltage surges may cause on the system. At the same time, the clearly defined target voltage value provides a clear safe endpoint for the rise process, preventing the voltage from climbing indefinitely. This controlled and linear voltage rise waveform not only helps protect the DC bus and downstream equipment, but also provides stable and reliable measurement conditions for subsequent calculation of capacitance parameters based on voltage changes and time intervals. Thus, while ensuring system safety, it supports high-precision and repeatable online capacitance identification.

[0131] In one exemplary embodiment, the current value corresponding to the voltage boost command is the average current value flowing through the DC bus over a time period.

[0132] It can be understood that when the voltage boost command is a voltage-type control command, its corresponding current value is the average current flowing through the DC bus over a given time period. Specifically, The signal is obtained through calculation using equation (1.14). Subsequently, to filter out the high-frequency ripple and noise generated by the switching of power devices in the signal, a smooth and stable DC component is extracted for accurate calculation. The transfer function of a first-order low-pass filter is as follows:

[0133] , formula (1.17);

[0134] The cutoff frequency of the filter is determined by setting it appropriately. This can produce a filter output with low ripple content that can follow the slow change trend of the current. During the ramp-up of the bus voltage, after the filtered value reaches a stable state, it is recorded as the final equivalent charging current value used for capacitor calculation.

[0135] This embodiment eliminates the need for an additional current sensor on the DC bus, fully utilizing the existing resources of the inverter, saving hardware costs, and improving system reliability. The use of a first-order low-pass filter with a well-defined mathematical definition for post-processing effectively and controllably eliminates switching noise and extracts the pure DC current component, thereby ensuring the accuracy of the current parameters in the input capacitance calculation formula. It combines high precision and high stability.

[0136] In one exemplary embodiment, determining at least two bus voltage values ​​and their corresponding times during the time period in which the bus voltage rises to the target bus voltage value includes:

[0137] Determine the fourth moment when the voltage boost command is issued to the frequency converter;

[0138] Determine the fifth moment when the bus voltage rises to the second bus voltage value;

[0139] Determine the sixth moment when the bus voltage rises to the target bus voltage value;

[0140] The fifth time point is later than the fourth time point, the sixth time point is later than the fifth time point, and the voltage value of the second bus is less than the voltage value of the target bus.

[0141] In this embodiment, at the fourth time... Set the target bus voltage value The bus voltage begins to rise. During the rise, the bus voltage is recorded as it rises to the second bus voltage value. The fifth moment of time And the bus voltage rises to the target bus voltage value. (i.e. The sixth moment .

[0142] In one exemplary embodiment, calculating the capacitance value of the bus-side capacitor based on the current value corresponding to the voltage boost command, at least two bus voltage values, and the corresponding time includes:

[0143] Determine the third time difference between the fourth and fifth time points, and the fourth time difference between the fifth and sixth time points;

[0144] The capacitance value of the bus-side capacitor is calculated using the average current value, the third time difference, the fourth time difference, the initial bus voltage value, the second bus voltage value, and the target bus voltage value.

[0145] In this embodiment, the third time difference is first calculated. and the fourth time difference Then, the capacitance value of the voltage-type control structure is obtained according to the following formula:

[0146] , formula (1.18).

[0147] In summary, this application utilizes two schemes to detect the bus-side capacitance value: online monitoring-based spontaneous current excitation and quasi-online detection-based average current model. Specifically, it employs a current-type control structure based on a specific current loop excitation and bus voltage limiting protection, and a bus voltage setpoint based on a ramp generator. DC bus current calculated using average value modeling The voltage-type control structure identifies the capacitance value of the DC-side capacitor, improving the performance of DC bus voltage control during shaft-driven power generation.

[0148] Please refer to Figure 6 This application also provides a bus-side capacitance determination device, including:

[0149] Control module 11 is used to send a voltage boost command to the frequency converter so that the bus voltage rises from the initial bus voltage value; the initial bus voltage value is the voltage value generated by the back electromotive force on the motor side when the frequency converter is not started.

[0150] The first determining module 12 is used to determine at least two bus voltage values ​​and the corresponding times during the time period when the bus voltage rises to the target bus voltage value.

[0151] The calculation module 13 is used to calculate the capacitance value of the bus-side capacitor based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time.

[0152] In one exemplary embodiment, the voltage boost command is a current-type control command;

[0153] Sending voltage boost commands to the frequency converter, including:

[0154] Inject a DC current reference value into the frequency converter so that the bus voltage starts to rise from the initial bus voltage value.

[0155] In one exemplary embodiment, the bus-side capacitance determination device further includes:

[0156] The second determining module is used to determine the first rated current of the motor;

[0157] The third determining module is used to determine the second rated current of the frequency converter;

[0158] The fourth determining module is used to determine the DC current reference value based on the first rated current and the second rated current.

[0159] In one exemplary embodiment, the target bus voltage value is a preset voltage safety limit.

[0160] During the time period when the bus voltage rises to the target bus voltage value, at least two bus voltage values ​​and their corresponding times are determined, including:

[0161] The first moment to determine the reference value of the injected DC current;

[0162] Determine the second moment when the bus voltage rises to the value of the first bus voltage;

[0163] Determine the third moment when the bus voltage rises to the preset voltage safety limit;

[0164] The second time point is later than the first time point, the third time point is later than the second time point, and the voltage value of the first bus is less than the preset voltage safety limit.

[0165] In one exemplary embodiment, the current value corresponding to the voltage boost command is a DC current reference value;

[0166] Based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time, calculate the capacitance value of the bus-side capacitor, including:

[0167] Determine the first time difference between the first and second moments, and the second time difference between the second and third moments;

[0168] The capacitance value of the bus-side capacitor is calculated using the DC current reference value, the first time difference, the second time difference, the initial bus voltage value, the first bus voltage value, and the preset voltage safety limit.

[0169] In one exemplary embodiment, the voltage boost command is a voltage-type control command;

[0170] Sending voltage boost commands to the frequency converter, including:

[0171] A voltage boost command is sent to the frequency converter. The voltage boost command is used to set the target bus voltage value and control the bus voltage to rise from the initial bus voltage value to the target bus voltage value at a preset slope.

[0172] In one exemplary embodiment, the current value corresponding to the voltage boost command is the average current value flowing through the DC bus over a time period.

[0173] In one exemplary embodiment, determining at least two bus voltage values ​​and their corresponding times during the time period in which the bus voltage rises to the target bus voltage value includes:

[0174] Determine the fourth moment when the voltage boost command is issued to the frequency converter;

[0175] Determine the fifth moment when the bus voltage rises to the second bus voltage value;

[0176] Determine the sixth moment when the bus voltage rises to the target bus voltage value;

[0177] The fifth time point is later than the fourth time point, the sixth time point is later than the fifth time point, and the voltage value of the second bus is less than the voltage value of the target bus.

[0178] In one exemplary embodiment, calculating the capacitance value of the bus-side capacitor based on the current value corresponding to the voltage boost command, at least two bus voltage values, and the corresponding time includes:

[0179] Determine the third time difference between the fourth and fifth time points, and the fourth time difference between the fifth and sixth time points;

[0180] The capacitance value of the bus-side capacitor is calculated using the average current value, the third time difference, the fourth time difference, the initial bus voltage value, the second bus voltage value, and the target bus voltage value.

[0181] For a description of the features in the embodiment corresponding to the bus-side capacitance determination device, please refer to the relevant description of the embodiment corresponding to the bus-side capacitance determination method, which will not be repeated here.

[0182] Embodiments of this application also provide an electronic device, including a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform the steps in any of the above embodiments of the bus-side capacitance determination method.

[0183] Embodiments of this application also provide a computer-readable storage medium storing a computer program, wherein the computer program is configured to execute the steps in any of the above embodiments of the bus-side capacitance determination method when it is run.

[0184] In one exemplary embodiment, the aforementioned computer-readable storage medium may include, but is not limited to, various media capable of storing computer programs, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard disk, magnetic disk, or optical disk.

[0185] The embodiments of this application also provide a computer program product, which includes a computer program that, when executed by a processor, implements the steps in any of the above embodiments of the bus-side capacitance determination method.

[0186] Embodiments of this application also provide another computer program product, including a non-volatile computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps in any of the above embodiments of the bus-side capacitance determination method.

[0187] It should also be noted that, in this specification, 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 a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0188] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining bus-side capacitance, characterized in that, include: A voltage boost command is issued to the frequency converter to cause the bus voltage to rise from the initial bus voltage value; the initial bus voltage value is the voltage value generated by the back electromotive force on the motor side when the frequency converter is not started. Within the time period during which the bus voltage rises to the target bus voltage value, at least two bus voltage values ​​and their corresponding times are determined; The capacitance value of the bus-side capacitor is calculated based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time.

2. The method for determining bus-side capacitance according to claim 1, characterized in that, The voltage boost command is a current-type control command; Sending voltage boost commands to the frequency converter, including: A DC current reference value is injected into the frequency converter to cause the bus voltage to rise from the initial bus voltage value.

3. The method for determining bus-side capacitance according to claim 2, characterized in that, The target bus voltage value is a preset voltage safety limit. During the time period when the bus voltage rises to the target bus voltage value, at least two bus voltage values ​​and their corresponding times are determined, including: Determine the first moment at which the DC current reference value is injected; Determine the second moment when the bus voltage rises to the first bus voltage value; Determine the third moment when the bus voltage rises to the preset voltage safety limit; The second time is later than the first time, the third time is later than the second time, and the first bus voltage value is less than the preset voltage safety limit.

4. The method for determining bus-side capacitance according to claim 3, characterized in that, The current value corresponding to the voltage boost command is the DC current reference value; Based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time, calculate the capacitance value of the bus-side capacitor, including: Determine a first time difference between the first time point and the second time point, and a second time difference between the second time point and the third time point; The capacitance value of the bus-side capacitor is calculated using the DC current reference value, the first time difference, the second time difference, the initial bus voltage value, the first bus voltage value, and the preset voltage safety limit.

5. The method for determining bus-side capacitance according to claim 1, characterized in that, The voltage boost command is a voltage-type control command; Sending voltage boost commands to the frequency converter, including: A voltage boost command is sent to the frequency converter. The voltage boost command is used to set the target bus voltage value and control the bus voltage to rise from the initial bus voltage value to the target bus voltage value at a preset slope.

6. The method for determining bus-side capacitance according to claim 5, characterized in that, During the time period when the bus voltage rises to the target bus voltage value, at least two bus voltage values ​​and their corresponding times are determined, including: Determine the fourth moment when the voltage boost command is issued to the frequency converter; Determine the fifth moment when the bus voltage rises to the second bus voltage value; Determine the sixth moment when the bus voltage rises to the target bus voltage value; The fifth time point is later than the fourth time point, the sixth time point is later than the fifth time point, and the second bus voltage value is less than the target bus voltage value.

7. The method for determining bus-side capacitance according to claim 6, characterized in that, The current value corresponding to the voltage-type control command is the average current value flowing through the DC bus during the time period. Based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time, calculate the capacitance value of the bus-side capacitor, including: Determine the third time difference between the fourth and fifth time points, and the fourth time difference between the fifth and sixth time points; The capacitance value of the bus-side capacitor is calculated using the average current value, the third time difference, the fourth time difference, the initial bus voltage value, the second bus voltage value, and the target bus voltage value.

8. A device for determining bus-side capacitance, characterized in that, include: The control module is used to send a voltage boost command to the frequency converter so that the bus voltage rises from the initial bus voltage value; the initial bus voltage value is the voltage value generated by the back electromotive force on the motor side when the frequency converter is not started. The first determining module is used to determine at least two bus voltage values ​​and their corresponding times during the time period in which the bus voltage rises to the target bus voltage value. The calculation module is used to calculate the capacitance value of the bus-side capacitor based on the current value corresponding to the voltage rise command, at least two bus voltage values, and the corresponding time.

9. An electronic device, characterized in that, include: Memory, used to store computer programs; A processor, configured to implement the steps of the bus-side capacitance determination method as described in any one of claims 1-7 when executing the computer program.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the bus-side capacitance determination method as described in any one of claims 1-7.

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