Frequency converter operating range adjustment method, device, medium and motor control system

Abstract

The application provides a frequency converter operation range adjusting method, device, medium and motor control system. The frequency converter comprises a DC bus and six half-bridges connected in parallel between the DC bus. Each half-bridge is connected by two IGBT modules in series. An output terminal is led out at the connection point of the two IGBT modules of each half-bridge. The six half-bridges are divided into three groups. The two output terminals of each group are connected to form a phase output connected with a load motor. First operation data of the load motor is monitored. The first operation data comprises torque and rotating speed of the load motor. The current operation interval of the frequency converter is determined based on the first operation data. A target control strategy is determined based on the current operation interval. The frequency converter is adjusted in operation range by using the target control strategy. Thus, only the electrical topology of the frequency converter is changed to a double parallel structure, the hardware is slightly changed, the cost is low and the implementation is easy. The output operation range of the frequency converter is improved, and the frequency converter can be applied to more different characteristic motors.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of frequency converters, in particular to a frequency converter operation range adjusting method, device, medium and motor control system. BACKGROUND

[0002] The output power of a frequency converter is determined by the torque and speed of a load motor. At low speed, the output power of the frequency converter is mainly determined by the load torque, that is, the output current amplitude. The output current amplitude of the frequency converter is limited by the maximum current amplitude of the power device used, such as IGBT, diode; at high speed, the output power of the frequency converter is mainly determined by the motor speed, that is, the output current frequency. In order to ensure the stability of the output current harmonics and the algorithm, the switching carrier ratio of the frequency converter needs to be kept above 10, that is, the upper limit of the output current frequency is limited by the switching frequency of the power device. Therefore, in order to improve the operation range of the frequency converter, it is necessary to increase the amplitude or frequency of the output current of the frequency converter, that is, to increase the maximum current amplitude or switching frequency of the power device.

[0003] In the prior art, in order to increase the output current amplitude of the frequency converter, a power module with larger conduction current is usually used; in order to increase the output current frequency of the frequency converter, the temperature rise of the power module at high switching frequency needs to be reduced. No matter which method is used, the output operation range of the frequency converter is improved from a single dimension, and the power module, or the power topology, or the heat dissipation mode of the existing frequency converter needs to be greatly changed and adjusted, which cannot be applied to motors with different characteristics. SUMMARY

[0004] Therefore, the embodiments of the present application provide a frequency converter operation range adjusting method, device, medium and motor control system to overcome the problem that the existing frequency converter operation range adjusting method needs to make great changes to the hardware of the frequency converter and the adjusting method is single, which is difficult to apply to motors with different characteristics.

[0005] According to a first aspect, the embodiments of the present application provide a frequency converter operation range adjusting method, comprising:

[0006] The frequency converter comprises a DC bus and six half-bridges connected in parallel between the DC bus, each half-bridge being composed of two IGBT modules connected in series, and an output terminal being led out at the connection point of the two IGBT modules of each half-bridge, and the six half-bridges being divided into three groups, and the two output terminals of each group being connected to form a phase output connected with a load motor, and the method comprises:

[0007] monitoring first operation data of the load motor, the first operation data comprising torque and speed of the load motor;

[0008] determining a current operation interval of the frequency converter based on the first operation data;

[0009] determining a target control strategy based on the current operation interval;

[0010] adjusting the operation range of the frequency converter by using the target control strategy.

[0011] Optionally, the determining the current operation interval of the frequency converter based on the first operation data comprises:

[0012] calculating the operation range of the frequency converter under different control strategies respectively;

[0013] dividing each operation range according to the control strategy to obtain a plurality of operation intervals, and the control strategy selection mode of different operation intervals is different;

[0014] extracting the current operation interval corresponding to the first operation data from the operation intervals.

[0015] Optionally, the determining the target control strategy based on the current operation interval comprises:

[0016] obtaining the control strategy selection mode corresponding to the current operation interval;

[0017] judging whether the control strategy selection mode corresponds to a plurality of control strategies;

[0018] when the control strategy selection mode corresponds to only one control strategy, determining the control strategy as the target control strategy.

[0019] Optionally, when the control strategy selection mode corresponds to only a plurality of control strategies, the determining the target control strategy based on the current operation interval further comprises:

[0020] obtaining second operation data of the frequency converter, the second operation data being operation data related to the loss of the frequency converter;

[0021] calculating the loss corresponding to a plurality of control strategies based on the second operation data respectively;

[0022] sorting the losses corresponding to the plurality of control strategies, and determining the control strategy with the lowest loss as the target control strategy.

[0023] Optionally, the control strategy comprises a single module control strategy, a parallel shunt control strategy and a parallel frequency division control strategy, wherein,

[0024] the single module control strategy has only one half-bridge in working state for each corresponding two half-bridges, and the driving signals of the upper and lower bridge arms of the half-bridge in working state are different;

[0025] The parallel shunt control strategy is that the upper bridge arm drive signals of each corresponding two half bridges are completely same, the lower bridge arm drive signals of each corresponding two half bridges are completely same, and the upper and lower bridge arm drive signals of each half bridge are different;

[0026] The parallel shunt control strategy is that the upper bridge arm drive signals of each corresponding two half bridges are completely same, the lower bridge arm drive signals of each corresponding two half bridges are completely same, and the upper and lower bridge arm drive signals of each half bridge are different;

[0027] Optionally, before extracting the current operation interval corresponding to the first operation data from each operation interval, the method further comprises:

[0028] determining whether the first operation data exceeds the maximum operation range corresponding to the frequency converter;

[0029] extracting the current operation interval corresponding to the first operation data from each operation interval when the first operation data does not exceed the maximum operation range of the frequency converter;

[0030] performing an alarm when the first operation data exceeds the maximum operation range of the frequency converter.

[0031] According to a second aspect, an embodiment of the present application provides a frequency converter operation range adjusting device, the frequency converter comprising: a direct current bus and six half bridges connected in parallel between the direct current bus, each half bridge comprising two IGBT modules connected in series, an output terminal being led out at the connection point of the two IGBT modules of each half bridge, the six half bridges being divided into three groups, the two output terminals of each group being connected to form a phase output connected with a load motor, the device comprising:

[0032] a monitoring module configured to monitor first operation data of the load motor, the first operation data comprising: torque and speed of the load motor;

[0033] a first processing module configured to determine a current operation interval of the frequency converter based on the first operation data;

[0034] a second processing module configured to determine a target control strategy based on the current operation interval;

[0035] a third processing module configured to adjust the operation range of the frequency converter by using the target control strategy.

[0036] According to a third aspect, an embodiment of the present application provides a motor control system, comprising: a frequency converter and a motor controller, wherein,

[0037] The frequency converter comprises: DC buses, six half-bridges connected in parallel between the DC buses, each half-bridge being composed of two IGBT modules connected in series, an output terminal being led out at the connection point of the two IGBT modules of each half-bridge, and the six half-bridges being divided into three groups, two output terminals of each group being connected to form a phase output connected with a load motor.

[0038] The motor controller is connected with the control terminals of the IGBT modules in each half-bridge respectively.

[0039] The motor controller comprises: a memory and a processor, which are connected with each other in communication, the memory storing computer instructions, and the processor executing the computer instructions to perform the frequency converter operating range adjusting method of the first aspect or any of the optional embodiments thereof.

[0040] Optionally, the motor control system further comprises:

[0041] a drive board corresponding to each half-bridge, the motor controller sending a drive signal to the IGBT modules of the corresponding half-bridge through the drive board;

[0042] The DC buses are provided with a capacitor.

[0043] According to a fourth aspect, an embodiment of the present application provides a computer readable storage medium storing computer instructions for causing a computer to execute the frequency converter operating range adjusting method of the first aspect or any of the optional embodiments thereof.

[0044] The technical scheme of the present application has the following advantages:

[0045] 1.The method and device for adjusting the operation range of a frequency converter, the frequency converter comprising: a DC bus and six half-bridges connected in parallel between the DC bus, each half-bridge comprising two IGBT modules connected in series, an output terminal being led out at the connection point of the two IGBT modules of each half-bridge, the six half-bridges being divided into three groups, the two output terminals of each group being connected to form a phase output connected with a load motor, the first operation data of the load motor being monitored, the first operation data comprising: the torque and the speed of the load motor, the current operation interval of the frequency converter being determined based on the first operation data, the target control strategy being determined based on the current operation interval, and the operation range of the frequency converter being adjusted by using the target control strategy. Thus, only the connection mode of each phase IGBT module in the original frequency converter topology is changed to a double-parallel structure, the hardware modification is small, the cost is low, and the implementation is easy. The current operation interval of the frequency converter is accurately determined by using the torque and the speed of the load motor as two dimensions, and then the target control strategy is reasonably selected to adjust the operation range of the frequency converter, which not only improves the output operation range of the frequency converter, but also is applicable to more different characteristic motors, and can be simultaneously applicable to a larger range of motor drives with high torque and low speed, low torque and high speed.

[0046] 2.The motor control system provided by the embodiment of the present application, comprising: a frequency converter and a motor controller, wherein the frequency converter comprises: a DC bus, six half-bridges connected in parallel between the DC bus, each half-bridge comprising two IGBT modules connected in series, an output terminal being led out at the connection point of the two IGBT modules of each half-bridge, the six half-bridges being divided into three groups, the two output terminals of each group being connected to form a phase output connected with a load motor; the motor controller is connected with the control end of the IGBT module in each half-bridge; the motor controller comprises: a memory and a processor, the memory and the processor being connected with each other in communication, the memory storing computer instructions, and the processor executing the computer instructions to execute the method for adjusting the operation range of the frequency converter provided by another embodiment of the present application. Thus, only the connection mode of each phase IGBT module in the original frequency converter topology is changed to a double-parallel structure, the hardware modification is small, the cost is low, and the implementation is easy. The current operation interval of the frequency converter is accurately determined by using the torque and the speed of the load motor as two dimensions, and then the target control strategy is reasonably selected to adjust the operation range of the frequency converter, which not only improves the output operation range of the frequency converter, but also is applicable to more different characteristic motors, and can be simultaneously applicable to a larger range of motor drives with high torque and low speed, low torque and high speed. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor based on these drawings.

[0048] Figure 1 A structure schematic diagram of a motor control system according to an embodiment of the present application;

[0049] Figure 2 A flow chart of a frequency converter operating range adjusting method according to an embodiment of the present application;

[0050] Figure 3A A waveform diagram of signals of a certain phase under a parallel shunt control strategy according to an embodiment of the present application;

[0051] Figure 3B A waveform diagram of signals of a certain phase under a parallel shunt control strategy according to an embodiment of the present application;

[0052] Figure 4A A frequency converter operating range change schematic diagram under a parallel shunt control strategy according to an embodiment of the present application;

[0053] Figure 4B A frequency converter operating range change schematic diagram under a parallel shunt control strategy according to an embodiment of the present application;

[0054] Figure 4C A frequency converter operating range schematic diagram corresponding to different operating intervals according to an embodiment of the present application;

[0055] Figure 5 A specific working process schematic diagram of a frequency converter operating range adjusting according to an embodiment of the present application;

[0056] Figure 6A Another frequency converter operating range schematic diagram corresponding to different operating intervals according to an embodiment of the present application;

[0057] Figure 6B Another specific working process schematic diagram of a frequency converter operating range adjusting according to an embodiment of the present application;

[0058] Figure 7 A structure schematic diagram of a frequency converter operating range adjusting device according to an embodiment of the present application;

[0059] Figure 8 A structure schematic diagram of a motor controller according to an embodiment of the present application. DETAILED DESCRIPTION

[0060] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0061] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0062] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements inside, it can be wireless connection, or it can be wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0063] The technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0064] In the prior art, to increase the output current amplitude of the frequency converter, a power module with larger on-current is usually used; and to increase the output current frequency of the frequency converter, the temperature rise of the power module at high switching frequency needs to be reduced. No matter which method is used, the output operating range of the frequency converter is improved from a single dimension, and the power module, or the power topology, or the heat dissipation mode of the existing frequency converter needs to be greatly changed and adjusted, which cannot be applied to motors with different characteristics.

[0065] Based on the above problems, the embodiments of the present application provide a motor control system, such as Figure 1As shown, the frequency converter operating range adjusting system specifically comprises: a frequency converter 101 and a motor controller 102, wherein the frequency converter 101 comprises: a DC bus 1, six half-bridges 2 connected in parallel between the DC bus 1, each half-bridge being composed of two IGBT modules 21 connected in series, an output terminal being led out at the connection point of the two IGBT modules 21 of each half-bridge 2, the six half-bridges 2 being divided into three groups, and the two output terminals of each group being connected to form a phase output connected with a load motor 3; and the motor controller 102 being connected with the control ends of the IGBT modules 21 in each half-bridge. For more details of the working process of the motor controller 102, refer to the related description of the method embodiment below, which will not be repeated here.

[0066] Specifically, as shown, Figure 1 The motor control system provided by the embodiment of the present application further comprises:

[0067] A drive board 103 corresponding to each half-bridge 2, the motor controller 102 sends a drive signal to the IGBT module 21 of the corresponding half-bridge 2 through the drive board 103. Wherein each drive board 103 corresponds to an independent PWM channel, the drive signal of each IGBT module 21 is sent through 6 pairs of independent PWM channels of the motor controller 102, and a capacitor C1 is arranged between the DC bus 1 to filter out interference in the electrical signal.

[0068] Through the cooperation of the above-mentioned components, the motor control system provided by the embodiment of the present application, by changing the connection mode of each phase IGBT module in the original frequency converter topology to a double-parallel structure, has small hardware changes, low cost and is easy to implement, by using the torque and speed of the load motor as two dimensions to accurately determine the current operating range of the frequency converter, and then reasonably selecting the target control strategy to adjust the operating range of the frequency converter, not only improves the output operating range of the frequency converter, but also can be applied to more different characteristics of the motor, and can be applied to a larger range of high-torque low-speed, low-torque high-speed motor drives.

[0069] The embodiment of the present application further provides a frequency converter operating range adjusting method, which is applied to the motor controller 102 as shown, Figure 1 As shown, the frequency converter operating range adjusting method specifically comprises the following steps: Figure 2

[0070] Step S101: monitoring first operating data of the load motor.

[0071] Wherein the first operating data comprises: torque and speed of the load motor.

[0072] Step S102: determining the current operating range of the frequency converter based on the first operating data.

[0073] ​Specifically, the historical reference data is obtained by driving the load motor of the same model frequency converter with different control strategies in advance, and recording the operating range of the frequency converter, and then the historical reference data is used to calculate the corresponding operating range of the frequency converter under different control strategies; the operating range is divided into multiple operating intervals according to the control strategy, and the control strategy selection mode of different operating intervals is different; the first running data corresponding to the current operating interval is extracted from each operating interval.

[0074] Specifically, the control strategy corresponding to the frequency converter as shown in Figure 1 includes single-module control strategy, parallel shunt control strategy, and parallel frequency division control strategy, wherein

[0075] The single-module control strategy has only one half-bridge in working state for each corresponding two half-bridges, and the driving signals of the upper and lower bridge arms of the half-bridge in working state are different. The parallel shunt control strategy has the same driving signals for the upper bridge arms of the corresponding two half-bridges, the same driving signals for the lower bridge arms of the corresponding two half-bridges, and different driving signals for the upper and lower bridge arms of each half-bridge; the parallel frequency division control strategy has time-interleaved on and off driving signals for the upper bridge arms of the corresponding two half-bridges, and time-interleaved on and off driving signals for the lower bridge arms of the corresponding two half-bridges, and only one IGBT module is in the on state at any time.

[0076] The single-module control strategy is similar to the control strategy for adjusting the operating range of the frequency converter in the prior art, and the specific control signal driving mode can refer to the related description in the prior art, which will not be repeated here.

[0077] The two independent PWM driving signals of the same phase have different PWM wave generation modes in the parallel shunt and parallel frequency division control strategies, and the A phase is taken as an example for illustration.

[0078] As shown in Figure 3A , TA is the control reference voltage value of the A phase, CV is the carrier signal of the A phase, TA1, TA2, TA3, and TA4 are respectively the driving signals of the four IGBTs of the A phase bridge arm in Figure 1 , AH is the total driving signal of the upper bridge arm output of the A phase, and AL is the total driving signal of the lower bridge arm output of the A phase. Under the parallel shunt control strategy, the upper bridge arm driving signals TA1 and TA3 are completely the same (i.e., the upper bridge arm IGBTs are turned on at the same time), and the lower bridge arm driving signals TA2 and TA4 are completely the same (i.e., the lower bridge arm IGBTs are turned on at the same time). Therefore, under the parallel shunt control strategy, the total current of the frequency converter A phase output is evenly divided in the two IGBT modules, and the output maximum current amplitude of the single-module topology frequency converter is increased by one time. Figure 4AThis diagram illustrates the change in the inverter's operating range before and after implementing a parallel shunt control strategy. The two dashed lines represent the constant power lines for the single-module topology and the parallel topology, respectively, with a 2:1 ratio between them. In the single-module topology, the maximum output torque at low speeds is limited by the maximum current amplitude of the power module; the maximum motor speed at low torque is limited by the maximum switching frequency of the power module; within the medium torque and medium speed range, both vary according to the maximum output power curve. Under the parallel shunt control strategy, the inverter's maximum output current amplitude doubles, thus doubling the maximum output torque at low speeds; the inverter's maximum switching frequency remains unchanged, therefore the maximum motor speed remains constant at low torque; within the medium torque and medium speed range, torque and speed vary according to the maximum output power curve.

[0079] like Figure 3B As shown, under the parallel frequency division control strategy, the upper bridge arm drive signals TA1 and TA3 are turned on alternately in a time-sharing manner, and the lower bridge arm drive signals TA2 and TA4 are turned on alternately in a time-sharing manner. The total drive signal AH of the upper bridge arm and the total drive signal AL of the lower bridge arm are consistent with the signals under the parallel current split control strategy. Under this control strategy, only one IGBT in phase A is in the on state at any given time, and the current flowing through that IGBT is the total output current of phase A. However, since both the upper and lower bridge arms are turned on in a time-sharing manner, the switching frequency of each IGBT is only half of the carrier frequency. This means that while keeping the switching frequency of each IGBT constant, the carrier frequency can be doubled, that is, the total switching frequency of phase A is doubled. Therefore, under the parallel frequency division control strategy, the total switching frequency of phase A of the inverter is evenly distributed in the two IGBT modules, which doubles the maximum output current frequency compared to the single-module topology inverter. Figure 4B This diagram illustrates the change in the inverter's operating range before and after implementing a parallel frequency division control strategy. The characteristics before and after parallel frequency division are shown. Figure 4A The characteristics before parallel current splitting are the same and will not be repeated. Under the parallel frequency splitting control strategy, the frequency of the inverter's maximum output current doubles, so the motor speed doubles under low torque conditions; the amplitude of the inverter's maximum output current remains unchanged, so the output torque remains unchanged under low speed conditions; in the medium torque and medium speed range, the torque and speed change according to the maximum output power curve.

[0080] Step S103: Determine the target control strategy based on the current operating range.

[0081] Specifically, different operating ranges correspond to different control strategies. The appropriate target control strategy is selected from the above control strategies based on the current operating range of the load motor.

[0082] Step S104: Use a target control strategy to adjust the operating range of the frequency converter.

[0083] By performing the above steps, the frequency converter operating range adjustment method provided by the embodiment of the application only needs to change the connection mode of each phase IGBT module in the original frequency converter topology to a double-parallel structure, has small hardware changes, low cost, and is easy to implement. The current operating range of the frequency converter is accurately determined by using the torque and speed of the load motor as two dimensions, and then a target control strategy is reasonably selected to adjust the operating range of the frequency converter, which not only improves the output operating range of the frequency converter, but also can be applied to more different characteristic motors, and can be applied to a larger range of high-torque low-speed, low-torque high-speed motor drives at the same time.

[0084] Specifically, in an embodiment, the step S103 specifically includes the following steps:

[0085] Step S301: Obtain the control strategy selection mode corresponding to the current operating range.

[0086] Among them, as can be known from the above steps, the control strategy selection mode corresponding to different operating ranges is different.

[0087] Step S302: Determine whether the control strategy selection mode corresponds to multiple control strategies.

[0088] Specifically, when the control strategy selection mode corresponds to only one control strategy, the control strategy is determined as the target control strategy. When the control strategy selection mode corresponds to multiple control strategies, the second operating data of the frequency converter is obtained, and the second operating data is the operating data related to the loss of the frequency converter. The loss corresponding to the multiple control strategies is calculated based on the second operating data. The losses corresponding to the multiple control strategies are sorted, and the control strategy with the lowest loss is determined as the target control strategy. Thus, when the multiple control strategies all meet the operating range requirements of the frequency converter, the control strategy with the lowest loss of the frequency converter is selected as the target control strategy, which reduces the loss of the frequency converter under partial load and saves energy consumption.

[0089] Specifically, in an embodiment, before extracting the current operating range corresponding to the first operating data from each operating range, the frequency converter operating range adjustment method provided by the embodiment of the application further includes the following steps:

[0090] Step S401: Determine whether the first operating data exceeds the maximum operating range corresponding to the frequency converter.

[0091] Specifically, since the output operating range of the frequency converter is jointly affected by the torque and the rotating speed of the load motor, the output power of the frequency converter can only be within a certain range, and the maximum operating range is the range formed by the motor torque and the rotating speed corresponding to the maximum power that the frequency converter can output when operating normally. When the first operating data does not exceed the maximum operating range of the frequency converter, the current operating interval corresponding to the first operating data is extracted from each operating interval. When the first operating data exceeds the maximum operating range of the frequency converter, an alarm is given. Thus, the frequency converter is prevented from being damaged abnormally, and the load motor is prevented from being abnormal due to the abnormality of the frequency converter, and the expansion of the failure range is avoided, and the maintenance personnel are reminded to maintain and repair in time, and the improvement demand for the heat dissipation design of the frequency converter is proposed.

[0092] In the embodiment of the application, since the motor controller adopts 6 pairs of independent PWM channels, the switching of the single-module, parallel shunt (such as Figure 3A ) and parallel frequency division (such as Figure 3B ) control strategies can be realized during the operation of the frequency converter. Therefore, the operating range of the frequency converter is as shown in Figure 4C , in the S1 operating interval, the three control strategies of single-module, parallel shunt and parallel frequency division can be adopted; in the S2 operating interval, the parallel shunt control strategy is adopted; in the S3 operating interval, the parallel frequency division control strategy is adopted; in the S4 operating interval, the parallel shunt and parallel frequency division control strategies can be adopted. Thus, the operating range of the frequency converter in two dimensions of output torque and rotating speed is improved, and the frequency converter can meet the operating requirements of more characteristic motors. The S5 region exceeds the operating range of the frequency converter, and this region is mainly affected by the heat dissipation design of the frequency converter, and the size of the region will decrease or even disappear with the improvement of the heat dissipation efficiency.

[0093] There is only one control strategy in S2 and S3 running interval, while there are 3 and 2 control strategies in S1 and S4 running interval, respectively, so the control strategy needs to be selected in the actual operation of the frequency converter. Under the premise of mature control strategies, the control strategy of S1 and S4 running interval needs to be selected according to the operating efficiency (i.e. power loss) of the frequency converter. The power consumption of the frequency converter is determined by five parameters, including output current, bus voltage, power device junction temperature, modulation algorithm (including conduction duty ratio and switching frequency) and loop parasitic inductance. Through the established loss simulation platform, the loss lookup table under the five parameter dimensions of different control strategies is obtained. In practical application, the bus voltage is basically maintained at a fixed value, and the loop parasitic inductance is also a fixed value after experimental determination; the output current is sampled by a current sensor and fed back to the motor controller at any time; after the heat resistance of the radiator is determined by experiment, the motor controller can predict the junction temperature of the power device by sampling the temperature of the radiator; the modulation algorithm is the internal data of the motor controller. Therefore, by giving the bus voltage and loop parasitic inductance, the sampled output current, the sampled and predicted power device junction temperature, and combining the modulation algorithm itself, the motor controller can obtain the loss value of each control strategy in different output running intervals, and select the optimal control strategy. Thus the optimal operating efficiency of the frequency converter under partial load is realized.

[0094] Exemplarily, as shown in Figure 5 , the frequency converter starts by single module control strategy, and then starts to judge the output running interval of the frequency converter at any time. If the output running interval is in S1 or S4, the lowest loss control strategy is selected in the loss lookup table by sampling the predicted junction temperature, output current, and modulation algorithm, and then switched; if the output running interval is in S2 or S3, the parallel shunt or parallel frequency division control strategy is directly selected and switched.

[0095] In practical application, the frequency converter can also start by single module control strategy in actual adjustment process, and then the output running range of the frequency converter is divided according to the optimal control strategy by sampling the predicted junction temperature, output current, and modulation algorithm at any time, as shown in Figure 6A , and the output running interval is judged. If the output running interval is in M1, the single module control strategy is selected and switched; if the output running interval is in M2, the parallel shunt control strategy is selected and switched; if the output running interval is in M3, the parallel frequency division control strategy is selected and switched, and the specific working process is as shown in Figure 6B .

[0096] Thus, by using the parallel shunt and parallel frequency division control strategy in combination, the effect of two-dimensional improvement of the operating range of the frequency converter is realized under the same hardware structure; by optimizing the power and control topology of the frequency converter, it is suitable for the control strategy of parallel shunt and parallel frequency division at the same time; and by monitoring the operating state and power consumption of the frequency converter, the internal control strategy is switched to realize the full output operating range under heavy load and the optimal operating efficiency under small load. Thus, with minimal hardware changes, the output operating range of the frequency converter is significantly improved, i.e. the application range. The method proposed in the present application has the advantages of easy implementation, easy porting, significant effect and the like. And the loss of the frequency converter under partial load is reduced, and the operating efficiency of the frequency converter under partial load is improved.

[0097] By performing the above steps, the frequency converter operating range adjustment method provided by the embodiment of the present application only needs to change the connection mode of each phase IGBT module in the original frequency converter topology to a double parallel structure, which has small hardware changes, low cost and is easy to implement. By using the torque and speed of the load motor as two dimensions to accurately determine the current operating range of the frequency converter, and then reasonably selecting the target control strategy to adjust the operating range of the frequency converter, not only the output operating range of the frequency converter is improved, but also the frequency converter can be applied to more different characteristics of the motor, and can be applied to a larger range of high torque low speed and low torque high speed motor drives.

[0098] The embodiment of the present application also provides a frequency converter operating range adjustment device, which is applied to a motor controller 102 as shown in Figure 1 as shown in Figure 7 The frequency converter operating range adjustment device comprises:

[0099] A monitoring module 11 is configured to monitor first operating data of the load motor, and the first operating data comprises torque and speed of the load motor. For details, refer to the related description of step S101 in the method embodiment, which will not be repeated here.

[0100] A first processing module 12 is configured to determine a current operating range of the frequency converter based on the first operating data. For details, refer to the related description of step S102 in the method embodiment, which will not be repeated here.

[0101] A second processing module 13 is configured to determine a target control strategy based on the current operating range. For details, refer to the related description of step S103 in the method embodiment, which will not be repeated here.

[0102] A third processing module 14 is configured to adjust the operating range of the frequency converter by using the target control strategy. For details, refer to the related description of step S104 in the method embodiment, which will not be repeated here.

[0103] The inverter operating range adjustment device provided in this embodiment of the invention is used to execute the inverter operating range adjustment method provided in the above embodiment. Its implementation method and principle are the same. For details, please refer to the relevant description of the above method embodiment, which will not be repeated here.

[0104] Through the synergistic cooperation of the above-mentioned components, the inverter operating range adjustment device provided in this embodiment of the invention only requires changing the connection method of each phase IGBT module in the original inverter topology to a dual parallel structure. The hardware modification is small, the cost is low, and it is easy to implement. By using the torque and speed of the load motor to accurately determine the current operating range of the inverter, and then reasonably selecting the target control strategy to adjust the operating range of the inverter, it not only improves the output operating range of the inverter, but also can be applied to motors with more different characteristics. It can be applied to a wider range of high torque and low speed motor drives and low torque and high speed motor drives.

[0105] Figure 8 A schematic diagram of the above-mentioned motor controller is shown, as follows: Figure 8 As shown, the motor controller includes a processor 901 and a memory 902, wherein the processor 901 and the memory 902 can be connected via a bus or other means. Figure 8 Taking the example of a connection between China and Israel via a bus.

[0106] Processor 901 can be a Central Processing Unit (CPU). Processor 901 can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above types of chips.

[0107] The memory 902, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the methods in the above method embodiments. The processor 901 executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions, and modules stored in the memory 902, thereby implementing the methods in the above method embodiments.

[0108] The memory 902 can include a program storage area and a data storage area, where the program storage area can store an operating system, application programs required by at least one function, and the data storage area can store data created by the processor 901 and the like. In addition, the memory 902 can include a high-speed random access memory, and can also include a non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state memory device. In some embodiments, the memory 902 can optionally include a memory disposed remotely from the processor 901, which can be connected to the processor 901 through a network. Examples of the above network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0109] One or more modules are stored in the memory 902, which, when executed by the processor 901, perform the methods in the above method embodiments.

[0110] The above motor controller specific details can be understood in correspondence with the above method embodiments corresponding to the relevant description and effects, which will not be described here.

[0111] Those skilled in the art can understand that all or part of the processes in the above embodiments can be completed by a computer program instructing related hardware, and the implemented program can be stored in a computer readable storage medium. When the program is executed, it can include the processes of the above embodiments. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD) or a solid state drive (SSD), etc. The storage medium can also include a combination of the above types of memories.

[0112] Although the embodiments of the present application are described in conjunction with the accompanying drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A method for adjusting the operating range of a frequency converter, characterized in that, The frequency converter includes: a DC bus and six half-bridges connected in parallel between the DC buses. Each half-bridge consists of two IGBT modules connected in series. An output terminal is led out from the connection point of the two IGBT modules in each half-bridge. The six half-bridges are divided into three groups, and the two output terminals of each group are connected to form a phase output connected to the load motor. The method includes: The first operating data of the load motor is monitored, and the first operating data includes the torque and speed of the load motor; The current operating range of the frequency converter is determined based on the first operating data; Determine the target control strategy based on the current operating range; The target control strategy is used to adjust the operating range of the frequency converter; Determining the current operating range of the frequency converter based on the first operating data includes: Calculate the operating range of the frequency converter under different control strategies; Each operating range is divided into multiple operating intervals according to the control strategy, and the control strategy selection method is different for different operating intervals; Extract the current operating interval corresponding to the first operating data from each operating interval.

2. The method according to claim 1, characterized in that, The determination of the target control strategy based on the current operating range includes: Obtain the control strategy selection method corresponding to the current operating range; Determine whether the control strategy selection method corresponds to multiple control strategies; When the control strategy selection method corresponds to only one control strategy, that control strategy is determined as the target control strategy.

3. The method according to claim 2, characterized in that, When the control strategy selection method corresponds to only multiple control strategies, the step of determining the target control strategy based on the current operating range further includes: Acquire the second operating data of the frequency converter, wherein the second operating data is operating data related to the losses of the frequency converter; Based on the second operating data, calculate the losses corresponding to multiple control strategies respectively; The losses corresponding to multiple control strategies are sorted, and the control strategy with the lowest loss is determined as the target control strategy.

4. The method according to claim 1, characterized in that, The control strategies include: single-module control strategy, parallel current-sharing control strategy, and parallel frequency-sharing control strategy, wherein... The single-module control strategy is that for each corresponding pair of half-bridges, only one half-bridge is in the working state, and the drive signals of the upper and lower arms of the working half-bridge are different. The parallel shunt control strategy is that the upper arm drive signals of each corresponding pair of half-bridges are exactly the same, the lower arm drive signals of each corresponding pair of half-bridges are exactly the same, and the upper and lower arm drive signals of each half-bridge are different. The parallel frequency division control strategy is that the upper arm drive signals of each corresponding two half-bridges are turned on in a time-division interleaved manner, and the lower arm drive signals of each corresponding two half-bridges are turned on in a time-division interleaved manner, and at any given time only one IGBT module is in the on state.

5. The method according to claim 1, characterized in that, Before extracting the current running interval corresponding to the first running data from each running interval, the method further includes: Determine whether the first operating data exceeds the maximum operating range corresponding to the frequency converter; When the first operating data does not exceed the maximum operating range of the frequency converter, the current operating interval corresponding to the first operating data is extracted from each operating interval; An alarm is triggered when the first operating data exceeds the maximum operating range of the frequency converter.

6. A frequency converter operating range adjustment device, characterized in that, The frequency converter includes: a DC bus and six half-bridges connected in parallel between the DC buses. Each half-bridge consists of two IGBT modules connected in series. An output terminal is led out from the connection point of the two IGBT modules in each half-bridge, dividing the six half-bridges into three groups. The two output terminals of each group are connected to form a phase output connected to the load motor. The device includes: A monitoring module is used to monitor the first operating data of the load motor, the first operating data including the torque and speed of the load motor; A first processing module is configured to determine the current operating range of the frequency converter based on the first operating data; the determination of the current operating range of the frequency converter based on the first operating data includes: calculating the operating range of the frequency converter under different control strategies; dividing each operating range into multiple operating ranges according to the control strategy, wherein the control strategy selection method is different for different operating ranges; and extracting the current operating range corresponding to the first operating data from each operating range. The second processing module is used to determine the target control strategy based on the current operating range; The third processing module is used to adjust the operating range of the frequency converter using the target control strategy.

7. A motor control system, characterized in that, include: Inverters and motor controllers, among which, The frequency converter includes: a DC bus, six half-bridges connected in parallel between the DC bus, each half-bridge consisting of two IGBT modules connected in series, and an output terminal leading out from the connection point of the two IGBT modules in each half-bridge, dividing the six half-bridges into three groups, with the two output terminals of each group connected to form a phase output connected to the load motor. The motor controller is connected to the control terminal of the IGBT module in each half-bridge. The motor controller includes a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to perform the method as described in any one of claims 1-5.

8. The motor control system according to claim 7, characterized in that, Also includes: A drive board is set up one-to-one with each half-bridge, and the motor controller sends drive signals to the IGBT modules of the corresponding half-bridge through the drive board; A capacitor is installed between the DC buses.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the method as described in any one of claims 1-5.

Images