Motor control device and control method

Abstract

The invention provides a motor control device and method, and relates to the technical field of power electronics. The motor control device is applied to a motor driving system and comprises a detection module and a controller. The controller comprises a plurality of working modes; the working modes correspond to different modulation signals. For any modulation interval, the detection module obtains the input voltage and the output voltage of the motor driving system in the current modulation interval. And the controller judges modulation parameters in the current modulation interval according to the input voltage and the output voltage, and then sends different modulation signals to the frequency conversion circuit according to the modulation parameters so as to drive the frequency conversion circuit to switch the motor driving system to a corresponding modulation state at a preset time point according to the corresponding modulation signals. Wherein each modulation state corresponds to different saturation intervals. On the basis, the modulation state of the motor driving system is switched at the preset time point according to the modulation parameters, the difference value between device temperatures under different modulation types is reduced, and the circuit loss is improved.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a motor control device and a control method. Background Art

[0002] In order to keep up with the trend of energy conservation, it is necessary to continuously improve the efficiency of various types of control motors, and the two-phase modulation scheme came into being.

[0003] In the prior art, the dual-phase modulation scheme usually controls any one of the output phases of the inverter to be in a saturated state, that is, the frequency conversion efficiency is improved by reducing the switching loss.

[0004] However, in the process of reducing switching losses, the electronic components of the upper and lower bridge arms in the dual-phase modulation scheme have different losses, which will lead to a large difference in losses and / or a large temperature difference between the upper and lower bridge arms, and the corresponding device temperature may even exceed the maximum temperature limit of the electronic components. Once the maximum temperature limit is exceeded, the electronic components will be damaged, thereby affecting the working efficiency of the control motor.

[0005] Based on this, there is an urgent need for a modulation scheme that can improve circuit losses and improve the working efficiency of controlling the motor. Summary of the invention

[0006] In view of this, an object of the present invention is to provide a motor control device and a control method, which can improve circuit loss and improve the working efficiency of controlling the motor.

[0007] In order to achieve the above purpose, the technical solution adopted by the embodiment of the present invention is as follows:

[0008] In a first aspect, the present invention provides a motor control device, which is applied to a motor drive system. The motor drive system includes a frequency conversion circuit, and the frequency conversion circuit includes a plurality of switch tubes. The motor control device includes a detection module and a controller. The detection module is connected to the controller. The controller is also connected to the control end of each switch tube. The controller includes multiple working modes. Each working mode corresponds to a different modulation signal.

[0009] For any modulation interval, a detection module is used to obtain the input voltage and output voltage of the motor drive system in the current modulation interval;

[0010] The controller is further used to determine the modulation parameters of the motor drive system in the current modulation interval according to the input voltage and the output voltage;

[0011] The controller is further used to send different modulation signals to the frequency conversion circuit according to the modulation parameters, so as to drive the frequency conversion circuit to switch the motor drive system to the corresponding modulation state at a preset time point according to the corresponding modulation signal;

[0012] Optionally, when the controller adopts a bi-phase modulation mode, the controller includes a first working state and a second working state; the first working state corresponds to a first modulation signal; the second working state corresponds to a second modulation signal;

[0013] A controller, configured to send a first modulation signal to the frequency conversion circuit according to the modulation parameter, so as to drive the frequency conversion circuit to switch the motor drive system to a first modulation state at a first preset time point;

[0014] or a controller, configured to send a second modulation signal to the frequency conversion circuit according to the modulation parameter, so as to drive the frequency conversion circuit to switch the motor drive system to a second modulation state at a second preset time point;

[0015] Among them, the saturation interval corresponding to the first modulation state is 120 degrees; the saturation interval corresponding to the second modulation state is 60 degrees.

[0016] Optionally, the minimum phase voltage in the first modulation state remains unchanged in any modulation interval and is equal to a first preset value;

[0017] For two adjacent modulation intervals, the maximum phase voltage in the second modulation state remains unchanged in the current modulation interval and is equal to the second preset value; in the next modulation interval, the minimum phase voltage is fixed to the first preset value;

[0018] The first preset value is smaller than the second preset value.

[0019] Optionally, under the condition that the modulation parameters include a voltage modulation rate,

[0020] The detection module is also used to determine the voltage modulation rate of the current motor drive system according to the input voltage and the output voltage;

[0021] The controller is further used to determine whether the voltage modulation rate is greater than or equal to a preset switching modulation rate;

[0022] The controller is further used to send a first modulation signal to the frequency conversion circuit under the condition that the voltage modulation rate is greater than or equal to the preset switching modulation rate, so as to switch the modulation state of the current motor drive system to the first modulation state at a first preset time point;

[0023] The controller is further used to send a second modulation signal to the frequency conversion circuit under the condition that the voltage modulation rate is less than the preset switching modulation rate, so as to switch the modulation state of the current motor drive system to the second modulation state at a second preset time point;

[0024] The saturation interval corresponding to the first modulation state is greater than the saturation interval corresponding to the second modulation state.

[0025] Optionally, under the condition that the voltage modulation rate is greater than or equal to the preset switching modulation rate, if the current motor drive system is in the second modulation state;

[0026] The controller is further used to send a first modulation signal to the frequency conversion circuit, so as to drive the frequency conversion circuit to switch the motor drive system to a first modulation state when the motor drive system is currently at a first preset time point;

[0027] The first preset time is the time point corresponding to the saturation output in the second modulation state.

[0028] Optionally, under the condition that the voltage modulation rate is less than the preset switching modulation rate, if the current motor drive system is in the first modulation state;

[0029] The controller is further used to send a second modulation signal to the frequency conversion circuit, so as to drive the frequency conversion circuit to switch the motor drive system to a second modulation state when the motor drive system is currently at a first preset time point;

[0030] The second preset time is the time point corresponding to the saturation output in the first modulation state.

[0031] Optionally, the detection module is further used to obtain a maximum loss value of the switch tube corresponding to the first modulation state;

[0032] The controller is also used to determine a preset switching modulation rate according to a maximum loss value of the switch tube corresponding to the first modulation state and a loss value of the switch tube corresponding to the three-phase modulation mode.

[0033] Optionally, the preset switching modulation rate is equal to 0.5.

[0034] In a second aspect, the present invention further provides a motor control method, which is applied to a motor control device, wherein the motor control device comprises a detection module and a controller; the detection module is connected to the controller; the controller is also connected to a control end of a down-conversion circuit of a motor drive system, and the motor control method comprises the following steps:

[0035] For any modulation interval, the detection module is used to obtain the input voltage and output voltage of the motor drive system in the current modulation interval;

[0036] Using the controller to determine the modulation parameters of the motor drive system in the current modulation interval according to the input voltage and the output voltage;

[0037] Using the controller to send different modulation signals to the frequency conversion circuit according to the modulation parameters, so as to drive the frequency conversion circuit to switch the motor drive system to the corresponding modulation state at a preset time point according to the corresponding modulation signal;

[0038] Wherein, each modulation state corresponds to a different saturation interval.

[0039] Optionally, under the condition that the modulation parameter includes a voltage modulation rate, the step of using the controller to determine the modulation parameter of the motor drive system in the current modulation interval according to the input voltage and the output voltage includes:

[0040] Determine the voltage modulation rate of the current motor drive system according to the input voltage and the output voltage by using the controller;

[0041] Using a controller to determine whether a voltage modulation rate is greater than or equal to a preset switching modulation rate;

[0042] Under the condition that the voltage modulation rate is greater than or equal to the preset switching modulation rate, the controller is used to send a first modulation signal to the frequency conversion circuit to switch the modulation state of the current motor drive system to the first modulation state at a first preset time point;

[0043] Under the condition that the voltage modulation rate is less than the preset switching modulation rate, the controller is used to send a second modulation signal to the frequency conversion circuit to switch the modulation state of the current motor drive system to the second modulation state at a second preset time point;

[0044] The saturation interval corresponding to the first modulation state is greater than the saturation interval corresponding to the second modulation state.

[0045] The motor control device and control method provided by the embodiments of the present invention have the following beneficial effects:

[0046] A motor control device provided by the present invention is applied to a motor drive system, the motor drive system includes a frequency conversion circuit, the frequency conversion circuit includes a plurality of switch tubes, and the motor control device includes a detection module and a controller; the detection module is connected to the controller; the controller is also connected to the control end of each switch tube; the controller includes multiple working modes; each working mode corresponds to a different modulation signal. For any modulation interval, the detection module is used to obtain the input voltage and output voltage of the motor drive system in the current modulation interval; the controller is used to judge the modulation parameters of the motor drive system in the current modulation interval according to the input voltage and the output voltage; the controller is also used to send different modulation signals to the frequency conversion circuit according to the modulation parameters, so as to drive the frequency conversion circuit to switch the motor drive system to the corresponding modulation state at a preset time point according to the corresponding modulation signal. Wherein, each modulation state corresponds to a different saturation interval. Based on this, the present invention switches the modulation state of the motor drive system at a preset time point according to the modulation parameters of the motor drive system in the current modulation interval, reduces the difference between the device temperatures under different modulation types, improves circuit loss, and improves the working efficiency of the motor drive system.

[0047] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0049] Figure 1 A schematic diagram of the structure of a motor drive system in the prior art is shown;

[0050] Figure 2 A module structure diagram of a motor control device provided by an embodiment of the present invention is shown;

[0051] Figure 3 A schematic diagram showing an output state corresponding to a first modulation state of a motor drive system according to an embodiment of the present invention is shown;

[0052] Figure 4 A schematic diagram showing an output state corresponding to the second modulation state of the motor drive system in an embodiment of the present invention is shown;

[0053] Figure 5 One of the schematic diagrams of the steps of the motor control method provided by an embodiment of the present invention is shown;

[0054] Figure 6 A schematic diagram of step 200 in an embodiment of the present invention is shown;

[0055] Figure 7 The second schematic diagram of the steps of the motor control method provided by the embodiment of the present invention is shown.

[0056] Icons: 10-motor control device; 11-detection module; 12-controller; 20-motor drive system; 21-frequency conversion circuit; 4a-first switch tube; 5a-second switch tube; 6a-third switch tube; 7a-fourth switch tube; 8a-fifth switch tube; 9a-sixth switch tube; 4b-first freewheeling diode; 5b-second freewheeling diode; 6b-third freewheeling diode; 7b-fourth freewheeling diode; 8b-fifth freewheeling diode; 9b-sixth freewheeling diode. DETAILED DESCRIPTION

[0057] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0058] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0059] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0060] As described in the background technology, although the frequency conversion efficiency can be improved by reducing switching losses, the different losses of electronic components in the upper and lower bridge arms in the dual-phase modulation scheme will cause the device temperature to exceed the maximum temperature limit of the electronic components, affecting the working efficiency of the control motor.

[0061] Based on this, the present invention provides a motor control solution, which can ensure that the device temperature is lower than the maximum temperature limit of the electronic components on the basis of reducing switching losses, thereby improving the working efficiency of the motor drive system.

[0062] The motor control device and control method provided by the present invention will be described in detail below.

[0063] Please refer to Figure 1 , Figure 1 A structural schematic diagram of a motor drive system in the prior art is shown, wherein the motor drive system 20 at least includes a frequency conversion circuit 21, and the frequency conversion circuit 21 is composed of multiple switching tubes, wherein the frequency conversion circuit 21 includes three output terminals, and each output terminal is respectively connected to each phase input terminal of the three-phase motor.

[0064] Please refer to Figure 2 , Figure 2The module structure diagram of the motor control device provided by the present invention is shown; the motor control device 10 in this embodiment is applied to the motor drive system, including a detection module 11 and a controller 12; the detection module 11 is connected to the controller 12; the controller 12 is also connected to the control end of each switch tube under the frequency conversion circuit 21 in the motor drive system 20, and the controller includes multiple working modes; each working mode corresponds to a different modulation signal.

[0065] Based on this, the controller in the present invention can send different modulation signals to each switch tube in the frequency conversion circuit in different working modes to change the turn-off / on frequency of each switch tube.

[0066] It should be noted that, in this embodiment, after the controller sends the modulation signal, the motor drive system needs to switch states at a preset time point.

[0067] In this embodiment, for any modulation interval, the detection module 11 is used to obtain the input voltage and output voltage of the motor drive system 20 in the current modulation interval.

[0068] The controller 12 is further used to determine the modulation parameters of the motor drive system in the current modulation interval according to the input voltage and the output voltage.

[0069] The controller 12 is also used to send different modulation signals to the frequency conversion circuit according to the modulation parameters, so as to drive the frequency conversion circuit to switch the motor drive system to a corresponding modulation state at a preset time point according to the corresponding modulation signal.

[0070] Wherein, each modulation state corresponds to a different saturation interval.

[0071] Based on this, the motor control device in the present invention can switch the modulation state of the motor drive system at a preset time point according to the modulation parameters of the motor drive system in the current modulation range, reduce the difference between the device temperatures under different modulation types, improve circuit losses, and improve the working efficiency of the motor drive system 20.

[0072] In one possible implementation, please refer to Figure 1The frequency conversion circuit 21 can be composed of six switch tubes and six freewheeling diodes, wherein each freewheeling diode is connected in parallel with one of the switch tubes, and the switch tubes connected in parallel with each freewheeling diode are different. For the sake of clarity, the six switch tubes are respectively represented as the first switch tube 4a, the second switch tube 5a, the third switch tube 6a, the fourth switch tube 7a, the fifth switch tube 8a, and the sixth switch tube 9a; the six freewheeling diodes are respectively represented as the first freewheeling diode 4b, the second freewheeling diode 5b, the third freewheeling diode 6b, the fourth freewheeling diode 7b, the fifth freewheeling diode 8b, and the sixth freewheeling diode 9b; wherein the first switch tube 4a is connected in parallel with the first freewheeling diode 4b, the second switch tube 5a is connected in parallel with the second freewheeling diode 5b, the third switch tube 6a is connected in parallel with the third freewheeling diode 6b, the fourth switch tube 7a is connected in parallel with the fourth freewheeling diode 7b, the fifth switch tube 8a is connected in parallel with the fifth freewheeling diode 8b, and the sixth switch tube 9a is connected in parallel with the sixth freewheeling diode 9b. The first end of the first switch tube 4a is connected to the first end of the third switch tube 6a and the first end of the fifth switch tube 8a; the second end of the first switch tube 4a is connected to the second end of the second switch tube 5a and the U-phase input end of the three-phase motor; the second end of the third switch tube 6a is connected to the second end of the fourth switch tube 7a and the V-phase input end of the three-phase motor; the second end of the fifth switch tube 8a is connected to the second end of the sixth switch tube 9a and the W-phase input end of the three-phase motor.

[0073] Among them, the six switching tubes under the frequency conversion circuit constitute the upper bridge arm side switching device and the lower bridge arm side switching device to provide power supply voltage for each phase of the three-phase motor and drive the three-phase motor to work.

[0074] It should be noted that the present embodiment does not limit the way in which the controller implements control, as long as different modulation signals are generated, for example, a pulse width modulation signal (PWM).

[0075] In one possible implementation, the controller can use space vector modulation, please refer to Figure 1 The on state and / or off state of the six switch tubes forming a loop composed of the upper arm side switch devices and the lower arm side switch devices respectively correspond to seven instantaneous voltage vectors, which are output by the corresponding pulse amplitude of the controller to drive the above-mentioned switch tubes.

[0076] In this method, each instantaneous voltage vector is composed of 6 basic output vectors with equal phases and magnitudes at a distance of π / 3 from each other and 1 zero vector. Based on this, after drawing each instantaneous voltage vector on the voltage vector plane, multiple restricted vector voltages can be obtained, and then any voltage vector can be generated based on the multiple restricted vector voltages to determine the corresponding modulation rate, that is, the following voltage modulation rate.

[0077] In this embodiment, if it is a dual-phase modulation mode, the controller 12 in this embodiment includes a first working state and a second working state; wherein the first working state corresponds to a first modulation signal; and the second working state corresponds to a second modulation signal.

[0078] Specifically, the controller 12 is used to send a first modulation signal to the frequency conversion circuit 21 according to the modulation parameters, so as to drive the frequency conversion circuit 21 to switch the motor drive system 20 to the first modulation state or the second modulation state at a first preset time point or a second preset time point.

[0079] It should be noted that in this embodiment, the motor drive system 20 can be driven by the controller 12 to switch the motor drive system 20 to the first modulation state (or from the second modulation state to the first modulation state) at a first preset time point; or to switch the motor drive system 20 to the second modulation state (or from the first modulation state to the second modulation state) at a second preset time point.

[0080] Among them, the saturation interval corresponding to the first modulation state is 120 degrees; the saturation interval corresponding to the second modulation state is 60 degrees.

[0081] Please continue to refer to Figure 1 After the motor drive system 20 switches to the first modulation state, the saturation interval (saturation output interval) corresponding to the two-phase modulation is 120 degrees, and the upper bridge arm side switch devices and the lower bridge arm side switch devices in the frequency conversion circuit 21 are saturated and output in the order of: U-phase lower bridge arm side switch devices, V-phase lower bridge arm side switch devices, and W-phase lower bridge arm side switch devices.

[0082] Please refer to Figure 3 , Figure 3 The output state of the motor drive system corresponding to the first modulation state is shown, and the output state includes the line voltages, phase voltages, output waveforms of the switch devices on the lower bridge arm side of the U phase, and output waveforms of the switch devices on the lower bridge arm side of the U phase in any modulation interval; wherein the line voltage is expressed as: the voltage difference between the U phase, the V phase, and the W phase in any modulation interval. At this time, the number of times the switch tube corresponding to the frequency conversion circuit is turned off and on is reduced to two-thirds of the original, which helps to improve the working efficiency of the motor drive system.

[0083] Please continue to refer to Figure 1 Similar to the previous embodiment, after the motor drive system switches to the second modulation state, the saturation interval (saturation output interval) corresponding to the two-phase modulation is 60 degrees, and the upper arm side switch devices and the lower arm side switch devices in the frequency conversion circuit are saturated and output in the order of: U-phase lower arm side switch devices, W-phase upper arm side switch devices, V-phase lower arm side switch devices, U-phase upper arm side switch devices, W-phase lower arm side switch devices, and V-phase upper arm side switch devices.

[0084] Please refer to Figure 4 , Figure 4 The output state of the motor drive system corresponding to the second modulation state is shown, and the output state includes the line voltages, phase voltages, the output waveforms of the switching devices on the lower bridge arm side of the U phase, and the output waveforms of the switching devices on the lower bridge arm side of the U phase in any modulation interval; at this time, the number of times the switch tube corresponding to the frequency conversion circuit is turned off and on is reduced to two-thirds of the original, which helps to improve the working efficiency of the motor drive system.

[0085] Furthermore, in the first modulation state, the minimum phase voltage remains unchanged in any modulation interval and is equal to the first preset value.

[0086] For two adjacent modulation intervals, the maximum phase voltage in the second modulation state remains unchanged in the current modulation interval and is equal to the second preset value; and the minimum phase voltage is fixed to the first preset value in the next modulation interval.

[0087] The first preset value is smaller than the second preset value.

[0088] In this embodiment, it is assumed that the first preset value is A and the second preset value is B. In the first modulation state, the minimum phase voltage remains unchanged in any modulation interval, and the corresponding value is equal to A, and dual-phase modulation is performed.

[0089] Correspondingly, in the second modulation state, the maximum phase voltage remains unchanged in the current modulation interval, and the corresponding value is equal to B; in the next modulation interval, the minimum phase voltage is fixed to remain unchanged, and the value is equal to A, and two-phase modulation is performed.

[0090] Based on this, under the condition that the modulation parameters include the voltage modulation rate, the detection module in this embodiment determines the voltage modulation rate of the current motor drive system based on the input voltage and the output voltage. Then, it is determined whether the voltage modulation rate is greater than or equal to the preset switching modulation rate. Under the condition that the voltage modulation rate is greater than or equal to the preset switching modulation rate, the controller sends a first modulation signal to the frequency conversion circuit to switch the modulation state of the current motor drive system to the first modulation state at a first preset time point. Otherwise, a second modulation signal is sent to the frequency conversion circuit to switch the modulation state of the current motor drive system to the second modulation state at a second time point.

[0091] In one possible implementation, under the condition that the voltage modulation rate is greater than or equal to the preset switching modulation rate, if the current motor drive system 20 is in the second modulation state; the controller 12 sends a first modulation signal to the frequency conversion circuit 21 in the motor drive system 20, so as to drive the frequency conversion circuit 21 to switch the motor drive system 20 to the first modulation state at a first preset time point, that is, at the time point corresponding to the saturated output in the second modulation state, for example, in the 60 degree interval.

[0092] If the current motor drive system 20 is in the first modulation state, the controller 12 sends a first control instruction to the motor drive system 20 to keep the drive frequency conversion circuit 21 in the current modulation state in the next modulation period.

[0093] In this embodiment, it is assumed that the current voltage modulation rate is represented as Ks, and the preset switching modulation rate is represented as Km. When Ks≥Km, if the current motor drive system is in the second modulation state, it switches to the first modulation state at the time point when the lower arm is saturated and outputs. Based on this, it can be ensured that there will be no change in saturated output during the switching of the two-phase modulation, ensuring the stability of the motor drive system. At the same time, compared with the single first modulation state, it can reduce the number of turn-on and turn-off of the switching tubes, achieving a more stable drive with fewer saturated phase switches.

[0094] In another possible implementation, under the condition that the voltage modulation rate is less than the preset switching modulation rate, if the current motor drive system 20 is in the first modulation state, the controller 12 sends a second modulation signal to the frequency conversion circuit 21 of the motor drive system 20 at the second preset time point, that is, the time point corresponding to the saturated output in the first modulation state, for example, in the 120-degree interval, to drive the frequency conversion circuit 21 to switch the motor drive system 20 to the second modulation state.

[0095] If the current motor drive system 20 is in the second modulation state, the controller 12 sends a second control instruction to the frequency conversion circuit 21 to keep the drive frequency conversion circuit 21 in the current modulation state in the next modulation period.

[0096] In this embodiment, it is assumed that the current voltage modulation rate is represented as Ks, and the preset switching modulation rate is represented as Km. When Ks < Km, if the current motor drive system is in the first modulation state, it switches to the second modulation state at the time point when the lower arm is saturated and outputs. Based on this, it can be ensured that there will be no change in saturated output during the switching of the two-phase modulation, ensuring the stability of the motor drive system. At the same time, compared with the single first modulation state, it can reduce the number of turn-on and turn-off of the switching tubes, achieving a more stable drive with fewer saturated phase switches.

[0097] Furthermore, in this embodiment, the motor control device is further configured to determine the preset switching modulation rate Km according to the first modulation state.

[0098] Specifically, the detection module 11 is configured to obtain the maximum loss value of the switching tube corresponding to the first modulation state. The controller 12 is configured to determine the preset switching modulation rate according to the maximum loss value of the switching tube corresponding to the first modulation state and the loss value of the switching tube corresponding to the three-phase modulation method.

[0099] In this embodiment, the preset switching modulation rate Km is the modulation rate that makes the maximum loss value of the switching tube corresponding to the first modulation state equal to the loss value of the switching tube corresponding to the three-phase modulation method.

[0100] In this embodiment, the preset switching modulation rate is equal to 0.5.

[0101] In summary, the present invention provides a motor control device, which is applied to a motor drive system, including a detection module and a control; the controller includes multiple working modes; each working mode corresponds to a different modulation signal. For any modulation interval, the detection module obtains the input voltage and output voltage of the motor drive system in the current modulation interval. The controller determines the modulation parameters in the current modulation interval based on the input voltage and the output voltage, and then sends different modulation signals to the frequency conversion circuit based on the modulation parameters to drive the frequency conversion circuit to switch the motor drive system to the corresponding modulation state at a preset time point according to the corresponding modulation signal. Among them, each modulation state corresponds to a different saturation interval.

[0102] Based on this, the present invention switches the modulation state of the motor drive system at a preset time point according to the modulation parameters, reduces the difference between the device temperatures under different modulation types, and improves circuit loss.

[0103] For the same idea as the previous embodiment, please refer to Figure 5 , Figure 5 FIG. 1 is a schematic diagram showing the steps of the motor control method in the present invention. The motor control method is applied to the motor control device of the first embodiment described above. Please continue to refer to FIG. Figure 2 The motor control device 10 includes a detection module 11 and a controller 12; the detection module 11 is connected to the controller 12; the controller 12 is also connected to the control end of the down-conversion circuit 21 of the motor drive system 20. In this embodiment, the motor control method includes steps 100 to 300.

[0104] Step 100: For any modulation interval, use a detection module to obtain an input voltage and an output voltage of the motor drive system in the current modulation interval.

[0105] Step 200: Using a controller to determine a modulation parameter of the motor drive system in a current modulation interval according to an input voltage and an output voltage.

[0106] Step 300: Using a controller to send different modulation signals to the frequency conversion circuit according to the modulation parameters, so as to drive the frequency conversion circuit to switch the motor drive system to a corresponding modulation state at a preset time point according to the corresponding modulation signal.

[0107] Wherein, each modulation state corresponds to a different saturation interval.

[0108] In this embodiment, please refer to Figure 6 , Figure 6A schematic diagram of the steps of step 200 in the present invention is shown. Under the condition that the modulation parameters include the voltage modulation rate, step 200 of using a controller to determine the modulation parameters of the motor drive system in the current modulation interval based on the input voltage and the output voltage includes steps 201 to 204.

[0109] Step 201: Determine the voltage modulation rate of the current motor drive system according to the input voltage and the output voltage using a controller.

[0110] Step 202 , using a controller to determine whether the voltage modulation rate is greater than or equal to a preset switching modulation rate; if so, executing step 203 ; otherwise, executing step 204 .

[0111] Step 203: Under the condition that the voltage modulation rate is greater than or equal to the preset switching modulation rate, use the controller to send a first modulation signal to the frequency conversion circuit to switch the modulation state of the current motor drive system to the first modulation state at a first preset time point.

[0112] Step 204: under the condition that the voltage modulation rate is less than the preset switching modulation rate, use the controller to send a second modulation signal to the frequency conversion circuit to switch the modulation state of the current motor drive system to the second modulation state at a second preset time point.

[0113] The saturation interval corresponding to the first modulation state is greater than the saturation interval corresponding to the second modulation state.

[0114] In this embodiment, after determining that the voltage modulation rate is greater than or equal to the preset switching modulation rate, the current motor drive system needs to be switched to the first modulation state. At this time, if the current motor drive system is in the second modulation state, the first modulation state can be sent by the controller to switch the motor drive system from the second modulation state to the first modulation state at a first preset time point; if the current motor drive system is in the first modulation state, the first control instruction sent by the controller can also be understood as sending a state maintenance instruction through the controller without changing the current modulation state of the motor drive system.

[0115] It should be noted that the motor drive system needs to switch to the first modulation state at the time point when the lower bridge arm is saturated. For example, when the corresponding saturation interval in the first modulation state is 120 degrees and the corresponding saturation interval in the second modulation state is 60 degrees, the current motor drive system is in the second modulation state, and the first preset time point is: the time point when the lower bridge arm is saturated when the modulation state before the change is not changed, that is, the time point when the lower bridge arm is saturated when the second modulation state is saturated (60 degree interval).

[0116] In this embodiment, after determining that the voltage modulation rate is less than the preset switching modulation rate, it is necessary to switch the current motor drive system to the second modulation state. At this time, if the current motor drive system is in the first modulation state, the second modulation signal sent by the controller can be used to switch from the first modulation state to the second modulation state at a second preset time point; if the current motor drive system is in the second modulation state, the second control instruction sent by the controller can also be understood as sending a state maintenance instruction through the controller without changing the current modulation state of the motor drive system.

[0117] It should be noted that the motor drive system needs to switch to the second modulation state at the time point when the lower bridge arm is saturated. For example, when the corresponding saturation interval in the first modulation state is 120 degrees and the corresponding saturation interval in the second modulation state is 60 degrees, the current motor drive system is in the first modulation state, and the second preset time point is: the time point when the lower bridge arm is saturated when the modulation state before the change is not changed, that is, the time point when the lower bridge arm is saturated when the first modulation state is saturated (i.e., the 120-degree interval).

[0118] In this embodiment, a certain running time can be set so that the operation ends when the running time condition is met. Figure 5 Based on the reference Figure 7 , Figure 7 Another schematic diagram of the steps of the motor control method in the present invention is shown, and step 300 further includes step 400 and step 500.

[0119] Step 400, determine whether the running time is greater than or equal to a preset threshold, if so, execute step 500; otherwise, continue to return to step 200 until the operation ends.

[0120] Step 500, end the operation.

[0121] Based on the above control method, when the voltage modulation rate is low, the motor drive system enters the second modulation state. At this time, the device losses of the upper and lower bridge arms are equal, and the maximum temperature of the device can be controlled at a lower value. When the voltage modulation rate is high, the motor drive system enters the first modulation state. At this time, the difference in device losses between the upper and lower bridge arms can also be maintained small, and the maximum temperature of the device can be controlled at a lower value, thereby achieving stable driving with less saturation phase switching. At the same time, switching is performed in the saturation interval of the switching device on the lower bridge arm side corresponding to the modulation state before switching, which can prevent changes in the saturated output during switching compared to the separate first modulation state and the separate second modulation state, thereby increasing the stability of the motor drive system.

[0122] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0123] In addition, the functional modules in the various embodiments of the present invention may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0124] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A motor control device, applied to a motor drive system, wherein the motor drive system comprises a frequency conversion circuit, wherein the frequency conversion circuit comprises a plurality of switch tubes, wherein: The motor control device includes a detection module and a controller; the detection module is connected to the controller; the controller is also connected to the control end of each switch tube; the controller includes multiple working modes; each working mode corresponds to a different modulation signal; For any modulation interval, the detection module is used to obtain the input voltage and output voltage of the motor drive system in the current modulation interval; The controller is further used to determine the modulation parameters of the motor drive system in the current modulation interval according to the input voltage and the output voltage; The controller is further used to send different modulation signals to the frequency conversion circuit according to the modulation parameters, so as to drive the frequency conversion circuit to switch the motor drive system to a corresponding modulation state at a preset time point according to the corresponding modulation signal; Wherein, each modulation state corresponds to a different saturation interval.

2. The motor control device according to claim 1, characterized in that: When the controller adopts a bi-phase modulation mode, the controller includes a first working state and a second working state; the first working state corresponds to a first modulation signal; the second working state corresponds to a second modulation signal; The controller is used to send a first modulation signal to the frequency conversion circuit according to the modulation parameter, so as to drive the frequency conversion circuit to switch the motor drive system to a first modulation state at a first preset time point; or the controller is used to send a second modulation signal to the frequency conversion circuit according to the modulation parameter, so as to drive the frequency conversion circuit to switch the motor drive system to a second modulation state at a second preset time point; Among them, the saturation interval corresponding to the first modulation state is 120 degrees; the saturation interval corresponding to the second modulation state is 60 degrees.

3. The motor control device according to claim 2, characterized in that: The minimum phase voltage in the first modulation state remains unchanged in any modulation interval and is equal to a first preset value; For two adjacent modulation intervals, the maximum phase voltage in the second modulation state remains unchanged in the current modulation interval and is equal to the second preset value; and the minimum phase voltage is fixed to the first preset value in the next modulation interval; The first preset value is smaller than the second preset value.

4. The motor control device according to any one of claims 1 to 3, characterized in that: Under the condition that the modulation parameters include the voltage modulation rate, The detection module is further used to determine the voltage modulation rate of the current motor drive system according to the input voltage and the output voltage; The controller is further used to determine whether the voltage modulation rate is greater than or equal to a preset switching modulation rate; The controller is further configured to send a first modulation signal to the frequency conversion circuit under the condition that the voltage modulation rate is greater than or equal to a preset switching modulation rate, so as to switch the current modulation state of the motor drive system to a first modulation state at a first preset time point; The controller is further configured to send a second modulation signal to the frequency conversion circuit under the condition that the voltage modulation rate is less than a preset switching modulation rate, so as to switch the current modulation state of the motor drive system to a second modulation state at a second preset time point; The saturation interval corresponding to the first modulation state is greater than the saturation interval corresponding to the second modulation state.

5. The motor control device according to claim 4, characterized in that: Under the condition that the voltage modulation rate is greater than or equal to the preset switching modulation rate, if the motor drive system is currently in the second modulation state; The controller is further used to send a first modulation signal to the frequency conversion circuit, so as to drive the frequency conversion circuit to switch the motor drive system to a first modulation state when the motor drive system is currently at a first preset time point; The first preset time is the time point corresponding to the saturation output in the second modulation state.

6. The motor control device according to claim 4, characterized in that: Under the condition that the voltage modulation rate is less than the preset switching modulation rate, if the motor drive system is currently in the first modulation state; The controller is further used to send a second modulation signal to the frequency conversion circuit, so as to drive the frequency conversion circuit to switch the motor drive system to a second modulation state when the motor drive system is currently at a first preset time point; The second preset time is the time point corresponding to the saturation output in the first modulation state.

7. The motor control device according to claim 4, characterized in that: The detection module is further used to obtain the maximum loss value of the switch tube corresponding to the first modulation state; The controller is further used to determine a preset switching modulation rate according to a maximum loss value of the switch tube corresponding to the first modulation state and a loss value of the switch tube corresponding to the three-phase modulation mode.

8. The motor control device according to claim 7, characterized in that: The preset switching modulation rate is equal to 0.

5.

9. A motor control method, characterized in that: Applied to a motor control device, the motor control device comprises a detection module and a controller; the detection module is connected to the controller; the controller is also connected to the control end of the down-conversion circuit of the motor drive system, and the motor control method comprises the following steps: For any modulation interval, using the detection module to obtain the input voltage and output voltage of the motor drive system in the current modulation interval; Determining a modulation parameter of the motor drive system in a current modulation interval according to the input voltage and the output voltage using the controller; Using the controller to send different modulation signals to the frequency conversion circuit according to the modulation parameters, so as to drive the frequency conversion circuit to switch the motor drive system to a corresponding modulation state at a preset time point according to the corresponding modulation signal; Wherein, each modulation state corresponds to a different saturation interval.

10. The motor control method according to claim 9, characterized in that: Under the condition that the modulation parameter includes the voltage modulation rate, the step of using the controller to determine the modulation parameter of the motor drive system in the current modulation interval according to the input voltage and the output voltage includes: Determine the voltage modulation rate of the current motor drive system according to the input voltage and the output voltage using the controller; Using the controller to determine whether the voltage modulation rate is greater than or equal to a preset switching modulation rate; Under the condition that the voltage modulation rate is greater than or equal to the preset switching modulation rate, the controller is used to send a first modulation signal to the frequency conversion circuit to switch the current modulation state of the motor drive system to the first modulation state at a first preset time point; Under the condition that the voltage modulation rate is less than the preset switching modulation rate, the controller is used to send a second modulation signal to the frequency conversion circuit to switch the current modulation state of the motor drive system to a second modulation state at a second preset time point; The saturation interval corresponding to the first modulation state is greater than the saturation interval corresponding to the second modulation state.

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