Motor driving device and motor driving method

Abstract

The invention relates to a motor driving device and a motor driving method, and the motor driving device comprises an MCU micro-control unit, a frequency conversion control module, an electronic bypass module and a mechanical bypass module. The MCU is used for controlling an inverter in the frequency conversion control module to limit the starting current to be smaller than the target current in the starting stage and controlling the frequency conversion control module to be closed after the rotating speed of the motor to be driven reaches the rated rotating speed. The electronic bypass module is triggered to be fully conducted and the mechanical bypass module is controlled to be short-circuited when the current of the to-be-driven motor crosses the zero point, and the target current is one time of rated current of the to-be-driven motor; and the MCU is also used for closing the electronic bypass module after determining that the mechanical bypass module is short-circuited. According to the invention, the problem that the voltage of a power grid drops suddenly because the starting current reaches 6-8 times of the rated current when the motor is directly started in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of motor driving, and in particular to a motor driving device and a motor driving method. BACKGROUND

[0002] The direct starting mode in the existing motor starting technology has the following problems: when directly starting, the starting current of the asynchronous motor reaches 6-8 times of the rated current, resulting in a sudden drop in the power grid voltage (voltage drop > 10%), which easily causes flicker in a weak power grid scenario such as a rural power grid, and interferes with the operation of precision equipment (such as medical instruments) in the same power grid.

[0003] In view of the above technical problems in the prior art, there is currently no effective solution. SUMMARY

[0004] The present application provides a motor driving device and a motor driving method to solve the problem that the starting current reaches 6-8 times of the rated current when the motor is directly started in the prior art.

[0005] In a first aspect, the present application provides a motor driving device, which comprises an MCU micro control unit, a variable frequency control module, an electronic bypass module and a mechanical bypass module. The MCU is configured to control the inverter in the variable frequency control module to limit the starting current to be less than a target current during the starting stage, control the variable frequency control module to be closed when the speed of the motor to be driven reaches the rated speed, and trigger the electronic bypass module to be fully conductive and control the mechanical bypass module to be short-circuited when the current of the motor to be driven is zero, wherein the target current is 1 times of the rated current of the motor to be driven. The MCU is further configured to close the electronic bypass module after determining that the mechanical bypass module is short-circuited.

[0006] Optionally, the variable frequency control module further comprises a rectifier bridge and a filter capacitor; wherein the rectifier bridge, the filter capacitor and the inverter are connected in parallel.

[0007] Optionally, the rectifier bridge is a three-phase bridge rectifier circuit, each phase rectifier circuit in the three-phase bridge rectifier circuit comprises two diodes, and each phase rectifier circuit is connected to three phases in the three-phase alternating current input respectively.

[0008] Optionally, the inverter comprises three groups of two-by-two series insulated gate bipolar transistors (IGBTs), the three groups of two-by-two series IGBTs are connected in parallel with each other, and each group of two-by-two series IGBTs is connected to three phases in the three-phase alternating current output respectively.

[0009] Optionally, the electronic bypass module comprises electronic switch components, wherein an input end of each group of electronic switch components is connected to an input end of one phase of the three-phase alternating current, and an output end of each group of electronic switch components is connected to an output end of one phase of the three-phase alternating current, and the electronic switch components comprise thyristors, insulated gate bipolar transistors (IGBTs) and COMS transistors.

[0010] Optionally, in the case where the electronic switch components are thyristors, each group of thyristors comprises two thyristors connected in anti-parallel; and in the case where the electronic switch components are IGBTs, each group of IGBTs comprises two IGBTs with their source and drain electrodes connected in series.

[0011] Optionally, the mechanical bypass module comprises three groups of mechanical contactors, wherein an input end of each group of mechanical contactors is connected to an input end of one phase of the three-phase alternating current, and an output end of each group of mechanical contactors is connected to an output end of one phase of the three-phase alternating current.

[0012] Optionally, the MCU is further configured to trigger the electronic bypass module to be fully conductive in a time-delay manner.

[0013] In a second aspect, a motor driving method based on the motor driving device of the first aspect is provided, and the method comprises the following steps: The MCU controls the variable frequency control module to limit the starting current to be less than a target current in the starting stage, wherein the target current is 1 times the rated current of the motor to be driven. The MCU controls the variable frequency control module to be turned off when the speed of the motor to be driven reaches the rated speed, and triggers the electronic bypass module to be fully conductive and controls the mechanical bypass module to be short-circuited at the zero-crossing point of the current of the motor to be driven. The MCU turns off the electronic bypass module after determining that the mechanical bypass module is short-circuited.

[0014] Optionally, the MCU triggers the electronic bypass module to be fully conductive at the zero-crossing point of the current of the motor to be driven, which comprises that the MCU triggers the electronic bypass module to be fully conductive in a time-delay manner at the zero-crossing point of the current of the motor to be driven.

[0015] Compared with the prior art, the technical scheme provided by the embodiment of the present application has the following advantages: in the embodiment of the present application, the inverter in the frequency conversion control module limits the starting current to below 1 times of the rated current in the starting stage, thereby avoiding the occurrence of grid voltage drop; in addition, when the switching is performed when the rotating speed reaches the rated rotating speed, the MCU can trigger the full conduction of the electronic bypass module and control the short circuit of the mechanical bypass module, so as to ensure that the full conduction of the electronic bypass module and the short circuit of the mechanical bypass module can be synchronized, thereby greatly reducing the risk of impact current rebound. Moreover, in the embodiment of the present application, the first conduction of the electronic bypass module can ensure the normal driving of the entire driving device, that is, the flow interruption of the entire driving device can be avoided, and the closing of the electronic bypass module after the combination of the mechanical bypass module does not affect the normal operation of the entire driving device. As can be seen, the fluctuation is small during the switching of the two bypass modules, and there is no mechanical arc, thereby making the noise of the entire driving device small during operation. BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0016] In order to more clearly illustrate the technical schemes in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiment or prior art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0017] One or more embodiments are exemplarily illustrated by pictures in the drawings corresponding thereto, and these exemplary illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, unless otherwise specified. The drawings in the drawings do not constitute a proportional limitation.

[0018] Figure 1 A structural schematic diagram of a motor driving device provided by the embodiment of the present application is shown in the figure. Figure 2 An optional structural schematic diagram of a motor driving device provided by the embodiment of the present application is shown in the figure. Figure 3 A flowchart of a motor driving method provided by the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0019] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0020] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplicity, the elements and settings of the particular examples in the following description are depicted. Of course, they are merely examples and are not intended to limit the present application. Furthermore, for example, the reference numerals included in the following description are only for clarity and are therefore, the same reference numerals are used for the same elements even though they are depicted in different examples. Such repetition is for the purpose of simplicity and clarity and it does not indicate a relationship between the various embodiments and / or settings discussed.

[0021] In order to solve the problem that the starting current reaches 6-8 times of the rated current when the motor is directly started in the related art, resulting in a sudden drop of the power grid voltage, the present application provides a motor driving device, as shown in Figure 1 The motor driving device includes a microcontroller unit (MCU) 101, a variable frequency control module 102, an electronic bypass module 103 and a mechanical bypass module 104. The microcontroller unit 101 is configured to control the inverter 21 in the variable frequency control module 102 to limit the starting current to be less than a target current during a starting stage, to control the variable frequency control module 102 to be closed when the speed of the motor to be driven reaches a rated speed, and to trigger the electronic bypass module 103 to be fully conductive and control the mechanical bypass module 104 to be short-circuited when the current of the motor to be driven is zero, wherein the target current is 1 times of the rated current of the motor to be driven. In this regard, in a specific example, the specific process of controlling the inverter in the variable frequency control module to limit the starting current to be less than the target current is as follows: during the starting process, the ratio of the output voltage and frequency of the inverter is accurately controlled to maintain the constant air gap flux of the motor, thereby avoiding magnetic saturation and limiting the current to be below 1 times of the rated current, and avoiding the problem that the starting current reaches 6-8 times of the rated current in the prior art, resulting in a sudden drop of the power grid voltage.

[0022] In addition, the current zero-crossing point of the motor to be driven in the embodiment of the present application refers to the time or position at which the current value in a three-phase alternating current circuit passes through zero. It can be seen that, in the embodiment of the present application, the electronic bypass module is triggered to be fully conductive at the current zero-crossing point, and the mechanical bypass module is controlled to be short-circuited, so as to ensure that the electronic bypass module is fully conductive and the mechanical bypass module is short-circuited synchronously. In the prior art, the bypass module of the frequency converter needs to be controlled by an additional contactor. When the switching is performed at the rated speed, the time for the contactor to be completely closed is uncertain, and each action cannot be consistent, resulting in that the motor counter electromotive force is out of synchronization with the grid phase, thereby forming an impact current rebound. In the present application, when the switching is performed at the rated speed, the electronic bypass module is triggered to be fully conductive and the mechanical bypass module is controlled to be short-circuited by the MCU, so as to ensure that the electronic bypass module is fully conductive and the mechanical bypass module is short-circuited synchronously, thereby greatly reducing the risk of impact current rebound.

[0023] The micro control unit 101 is also configured to close the electronic bypass module 103 after determining that the mechanical bypass module 104 is short-circuited.

[0024] After the closing of the variable frequency control module 102 and the opening of the electronic bypass module 103 and the short-circuiting of the mechanical bypass module 104 are completed, the electronic bypass module 103 is controlled to be closed again. Since the mechanical bypass module 104 has a relatively long action time, usually tens of ms to hundreds of ms, and the electronic bypass module is an electronic component and has a relatively fast action time, usually 5-20us, the electronic bypass module 103 is first turned on to ensure that the entire driving device can normally drive the motor, that is, the entire driving device can avoid current interruption during driving. The closing of the electronic bypass module 103 after the combination of the mechanical bypass module 104 does not affect the normal operation of the entire driving device. It can be seen that the fluctuation is small during the switching of the two bypass modules, and there is no mechanical arc, so that the noise of the entire driving device during operation is small.

[0025] Further, in the embodiment of the present application, the MCU is also configured to trigger the electronic bypass module 103 to be fully conductive in a delay target time length. In specific examples, the target time length is usually set to 100us, and can also be tens of us, and the value range can be 5-200us. Specifically, the delay time when the inverter in the variable frequency control module is closed can be referred to, that is, the electronic bypass module 103 is triggered to be fully conductive by delay, which can offset the opening inertia of the variable frequency control module 102, that is, there is a delay when the variable frequency control module 102 is closed, so as to prevent the variable frequency control module 102 from generating a circulating current with the grid.

[0026] Further, as shown in FIG. 1, the driving device comprises a micro control unit 101, a variable frequency control module 102, an electronic bypass module 103 and a mechanical bypass module 104. Figure 2As shown, the frequency conversion control module 102 in the embodiment of the present application includes a rectifier bridge 22 and a filter capacitor 23; wherein the rectifier bridge 22, the filter capacitor 23 and the inverter 21 are connected in parallel.

[0027] As shown, the rectifier bridge 22 is a three-phase bridge rectifier circuit, each phase rectifier circuit in the three-phase bridge rectifier circuit includes two diodes, and each phase rectifier circuit is connected to three phases in the three-phase alternating current input respectively. Figure 2

[0028] As shown, the inverter 21 includes three groups of two-by-two series insulated gate bipolar transistors (IGBTs), the three groups of two-by-two series IGBTs are connected in parallel with each other, and each group of two-by-two series IGBTs is connected to three phases in the three-phase alternating current output respectively. Figure 2

[0029] To this end, the inverter 21 can include six insulated gate bipolar transistors (IGBT1-IGBT6). The six IGBTs are divided into three groups, each group containing two IGBTs connected in series between the positive (P) and negative (N) DC bus. Specifically, the first group is IGBT1 and IGBT2 in series, the second group is IGBT3 and IGBT4 in series, and the third group is IGBT5 and IGBT6 in series.

[0030] As shown, the electronic bypass module 103 includes electronic switching components, wherein the input end of each group of electronic switching components is connected to one phase of the three-phase alternating current input, and the output end of each group of electronic switching components is connected to one phase of the three-phase alternating current output. In a specific example of the embodiment of the present application, the electronic switching component can be any one of a thyristor, an insulated gate bipolar transistor (IGBT) and a COMS transistor. Further, in the case of a thyristor as an electronic switching component, each group of thyristors includes two thyristors connected in anti-parallel; in the case of an IGBT as an electronic switching component, each group of IGBTs includes two source and drain series insulated gate bipolar transistors (IGBTs).

[0031] Each group of thyristors contains two thyristors connected in anti-parallel, which allows current to flow in both directions and is suitable for alternating current circuits. The switching speed of the electronic bypass module 103 is extremely fast (on the order of milliseconds), which can achieve seamless or static switching of the load from inverter power supply to mains power supply, usually triggered immediately upon detection of inverter failure.

[0032] As shown, the mechanical bypass module 104 includes three groups of mechanical contactors, wherein the input end of each group of mechanical contactors is connected to one phase of the three-phase alternating current input, and the output end of each group of mechanical contactors is connected to one phase of the three-phase alternating current output.

[0033] Further, as shown, the mechanical bypass module 104 includes three groups of mechanical contactors, wherein the input end of each group of mechanical contactors is connected to one phase of the three-phase alternating current input, and the output end of each group of mechanical contactors is connected to one phase of the three-phase alternating current output.​​Figure 2 As shown, the frequency converter control module 102 includes three-phase AC power input terminals R, S, T, and three-phase AC output terminals A, B, C.

[0034] The electronic bypass module 103 includes three-phase AC power input terminals a1, b1, and c1, device output terminals a2, b2, and c2, and anti-parallel thyristors (SCRs).

[0035] The mechanical bypass module 104 includes three-phase AC power input terminals a11, b11, c11, device output terminals a22, b22, c22, and a mechanical contactor.

[0036] Based on this, such as Figure 2 As shown, the three-phase AC power input terminal R of the frequency converter control module 102 is connected to the three-phase AC power input terminal a1 of the electronic bypass module 103 and the three-phase AC power input terminal a11 of the mechanical bypass module 104. The three-phase AC power input terminal S of the frequency converter control module 102 is connected to the three-phase AC power input terminal b1 of the electronic bypass module 103 and the three-phase AC power input terminal b11 of the mechanical bypass module 104. The three-phase AC power input terminal T of the frequency converter control module 102 is connected to the three-phase AC power input terminal c1 of the electronic bypass module 103 and the three-phase AC power input terminal c11 of the mechanical bypass module 104.

[0037] Furthermore, the three-phase AC output terminal A of the frequency converter control module 102 is connected to the three-phase AC output terminal a2 of the electronic bypass module 103 and the three-phase AC output terminal a22 of the mechanical bypass module 104. The three-phase AC output terminal B of the frequency converter control module 102 is connected to the three-phase AC output terminal b2 of the electronic bypass module 103 and the three-phase AC output terminal b22 of the mechanical bypass module 104. The three-phase AC output terminal C of the frequency converter control module 102 is connected to the three-phase AC output terminal c2 of the electronic bypass module 103 and the three-phase AC output terminal c22 of the mechanical bypass module 104.

[0038] Based on the above explanation of the motor drive device in the embodiments of this application, the following further explanation is provided in conjunction with the specific drive process, such as... Figure 3 As shown in the figure, this application provides a motor driving method, the steps of which include: Step 301: During the startup phase, the MCU controls the frequency converter control module to limit the startup current to be less than the target current; wherein, the target current is 1 times the rated current of the motor to be driven. To this end, in the starting phase, the frequency conversion control module can convert the grid input into a 0-50Hz adjustable PWM output, and then control the ratio of output voltage and frequency through the inverter in the frequency conversion control module to maintain the constant motor air gap flux, so that the current can be limited below 1 times the rated current. It is far lower than the impact current of direct start, which is enough to ensure smooth start and no impact on the grid; at the same time, it can provide more starting torque than smaller starting current (such as 0.3 times rated), so that the motor can accelerate faster, which is suitable for load starting scenes.

[0039] Step 302, the MCU controls the frequency conversion control module to be closed after the speed of the motor to be driven reaches the rated speed, and triggers the electronic bypass module to be fully on and controls the mechanical bypass module to be short-circuited at the current zero point of the motor to be driven; In the present application, when the speed reaches the rated speed for switching, the MCU can trigger the electronic bypass module to be fully on and control the mechanical bypass module to be short-circuited to ensure that the electronic bypass module is fully on and the mechanical bypass module is short-circuited synchronously, thereby greatly reducing the risk of impact current rebound.

[0040] Further, in specific examples, the MCU triggers the electronic bypass module to be fully on at the current zero point of the motor to be driven, that is, the MCU triggers the electronic bypass module to be fully on at the current zero point of the motor to be driven after a delay target duration. If the switching is forced at a non-zero current point, a huge voltage spike and arc will be generated due to the inductance characteristics, which will seriously damage the switching device. When switching at the zero crossing point, the current and voltage are theoretically zero, and arcless switching can be achieved, greatly improving the reliability and service life of the system.

[0041] In addition, in this way, by triggering the electronic bypass module to be fully on with a delay, the opening inertia of the frequency conversion control module can be offset, that is, there is a delay when the frequency conversion control module stops outputting, so that the circulation between the frequency conversion control module and the grid can be prevented. That is, by triggering with a delay, it can be ensured that when the electronic bypass is on, the contacts of the mechanical bypass are very close to or have just completed closure, thereby greatly shortening the time during which the electronic bypass needs to bear a large current and reducing the thermal stress thereof. If there is no delay, the electronic bypass is turned on instantaneously, and the mechanical contacts may have a short period of current distribution uncertainty during the closing process. Delay triggering makes the switching process more orderly and controllable. It should be noted that for mechanical bypass modules of different models and different action times, the target duration can be adjusted through software, thereby enhancing the universality and flexibility of the method.

[0042] Step 303, the MCU closes the electronic bypass module after determining that the mechanical bypass module is short-circuited.

[0043] It can be seen that, in confirming that the contact of the mechanical bypass (contactor) has been reliably closed and carries current, its on-voltage drop and loss are much lower than those of the electronic bypass (thyristor). At this time, the electronic bypass has completed its temporary bridge mission. Turn off the electronic bypass module, so that it is completely removed from the circuit, eliminating its inherent conduction loss, and the system enters the most efficient operating state carried by the mechanical bypass. At this time, the entire variable frequency control module and electronic bypass module are not electrified and do not work, and the system loss is minimized.

[0044] It can be seen that, for steps 301 to 303, in the starting stage, the variable frequency control module limits the starting current to be less than or equal to 1 times the rated current of the motor; after reaching the rated speed, the MCU detects the zero point of the main circuit current, turns off the variable frequency control module, and delays the trigger of the electronic bypass module full conduction, and quickly shorts the input and output of the device in phase, realizes zero impact switching, and triggers the mechanical bypass module to short the input and output of the device in phase. Turn off the electronic bypass module after receiving the signal of the mechanical bypass module input and output shorting. For this reason, since the mechanical bypass module has a longer action time, usually tens to hundreds of ms of action time, and the electronic bypass module is an electronic component, the action time is faster, usually 5-20us, therefore, the electronic bypass module is turned on first to ensure the normal driving of the entire driving device, that is, the flow of the entire driving device can be avoided, and the electronic bypass module is turned off after the mechanical bypass module is combined. It does not affect the normal work of the entire driving device. It can be seen that the fluctuation is small during the switching of the two bypass modules, and there is no mechanical arc, so that the noise of the entire driving device during operation is small.

[0045] Through the manner of the embodiment of the present application, in the actual test process, taking a 75kW water pump as an example, the actual test performance of the present application is compared with the performance of the prior art, and table 1 is a performance comparison table of the actual test values of the present application and the actual test values of the prior art, as shown in table 1.

[0046] Table 1

[0047] Therefore, by means of the embodiment of the application, the starting current can be less than or equal to 1 times rated current, compared with the multiple times of rated current of the starting current of the motor in the prior art, the grid voltage does not suddenly drop, and the flicker is not caused in the weak grid scene such as rural power grid, and the operation of the precision equipment (such as medical instruments) in the same grid is not disturbed. In addition, by means of the embodiment of the application, the bypass switching fluctuation is less than 2%, and there is no mechanical arc, while in the prior art, the mechanical contact action delay (5-200 ms) causes the current to be discontinuous, and the instantaneous current fluctuation is greater than 20%. In addition, by means of the embodiment of the application, the total harmonic distortion rate of the current after the bypass operation is approximately equal to 0, and the noise is also approximately equal to 0.

[0048] In summary, by means of the motor driving device and the driving method in the embodiment of the application, the frequency conversion soft start and the non-impact bypass of the electronic switch in the electronic bypass module are integrated, the starting current is limited to be less than or equal to 1 times rated current by the frequency conversion module in the starting stage; after the rated speed is reached, the MCU triggers the full conduction of the electronic switch in the electronic bypass module at the current zero point, and simultaneously closes the mechanical bypass module to realize zero-impact switching, and the noise after the bypass is approximately equal to 0 dB and the THDi is approximately equal to 0%, and there is no mechanical arc, which is suitable for the medical, residential and other places with poor grid capacity and noise sensitivity.

[0049] The device embodiments described above are only schematic, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, that is, they can be located in one place or distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the embodiment.

[0050] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be realized by means of software plus a general hardware platform, and of course, it can also be realized by hardware. Based on such understanding, the above technical solutions or the part that contributes to the related art can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiment.

[0051] It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and "has" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order

[0052] The above description is merely that of the specific embodiments of the application and as such is not to be taken in a limiting sense. Various modifications and alterations of the embodiments described herein will become apparent to those skilled in the art from the foregoing description, which does not limit the generality presented. It is the intention that all such modifications and alterations be considered equaliy by the spirit and scope of this application. It is therefore intended to cover in the appended claims all such changes and alterations that come within the scope of this application.

Claims

1. An electric motor drive apparatus, characterized by comprising: The MCU micro control unit, a variable frequency control module, an electronic bypass module and a mechanical bypass module are included. The MCU is configured to control the inverter in the variable frequency control module to limit the starting current to be less than a target current in a starting stage, control the variable frequency control module to be closed when the rotating speed of the motor to be driven reaches a rated rotating speed, and trigger the electronic bypass module to be fully on and control the mechanical bypass module to be short-circuited when the current of the motor to be driven is zero. The MCU is further configured to close the electronic bypass module after determining that the mechanical bypass module is short-circuited.

2. The apparatus of claim 1, wherein, The variable frequency control module further includes a rectifier bridge and a filter capacitor, wherein the rectifier bridge, the filter capacitor and the inverter are connected in parallel.

3. The apparatus of claim 2, wherein, The rectifier bridge is a three-phase bridge rectifier circuit, each phase rectifier circuit in the three-phase bridge rectifier circuit includes two diodes, and each phase rectifier circuit is connected to three phases in three-phase alternating current input respectively.

4. The apparatus of claim 2, wherein, The inverter includes three groups of IGBTs which are connected in series in pairs, the three groups of IGBTs connected in series in pairs are connected in parallel with each other, and each group of IGBTs connected in series in pairs is connected to three phases in three-phase alternating current output respectively.

5. The apparatus of claim 1, wherein, The electronic bypass module includes three groups of electronic switching components, wherein the input end of each group of electronic switching components is connected to one phase of three-phase alternating current input, the output end of each group of electronic switching components is connected to one phase of three-phase alternating current output, and the electronic switching components include thyristors, IGBTs and COMS transistors.

6. The apparatus of claim 5, wherein, In the case that the electronic switching component is a thyristor, each group of thyristors includes two thyristors connected in reverse parallel; in the case that the electronic switching component is an IGBT, each group of IGBTs includes two IGBTs connected in series.

7. The apparatus of claim 1, wherein, The mechanical bypass module includes three groups of mechanical contactors, wherein the input end of each group of mechanical contactors is connected to one phase of three-phase alternating current input, and the output end of each group of mechanical contactors is connected to one phase of three-phase alternating current output.

8. The apparatus of claim 1, wherein, The MCU is further configured to trigger in a time-delay target duration when triggering the electronic bypass module to be fully on.

9. A motor drive method based on the motor drive apparatus according to any one of claims 1 to 8, characterized by, The method includes: The MCU controls the variable frequency control module to limit the starting current to be less than a target current in a starting stage; wherein the target current is 1 times of the rated current of the motor to be driven. The MCU controls the variable frequency control module to be closed when the rotating speed of the motor to be driven reaches a rated rotating speed, and triggers the electronic bypass module to be fully on and controls the mechanical bypass module to be short-circuited when the current of the motor to be driven is zero. The MCU closes the electronic bypass module after determining that the mechanical bypass module is short-circuited.

10. The method of claim 9, wherein, The MCU triggers the electronic bypass module to be fully on in a time-delay target duration when the current of the motor to be driven is zero. ​

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