A cascaded driving system, a control method, a device and a storage medium

Abstract

The application belongs to the field of new energy vehicle motor control, and particularly relates to a cascaded driving system, a control method, equipment and a storage medium. The driving system comprises: a plurality of motor controller modules and driving motors, each motor controller module is connected with a driving motor; the motor controller modules are connected in series; the motor controller module comprises a support capacitor and an inverter unit; two ends of the support capacitor are respectively connected with positive and negative poles of a direct current power supply, and the support capacitor is connected in parallel with the inverter unit; an insulating pad is arranged on a stator of the driving motor, and an insulating bearing is adopted for a rotor of the driving motor. The application has the effect that low-voltage inverters can be used in high-voltage applications.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of new energy vehicle motor control, and particularly relates to a cascaded driving system, a control method, equipment and a storage medium. BACKGROUND

[0002] In recent years, more and more people like new energy vehicles, and new energy vehicles have ushered in an era of rapid development. The motor driving system is one part of the new energy vehicle, and the motor driving system refers to the overall system for controlling the operation of the motor. With the increase of the direct current voltage of the motor driving system, the voltage withstand capability of the power device in the motor driving system needs to be improved to adapt to the increased direct current voltage.

[0003] In the related art, when the direct current voltage is increased, the most direct solution is to select a high-voltage power device.

[0004] In the above related technology, the high-voltage power device is usually expensive and has large loss, which increases the use cost. SUMMARY

[0005] The technical problem to be solved by the application is to provide a cascaded driving system, a control method, equipment and a storage medium, which realizes the effect of a high-voltage device by using a low-voltage device, thereby saving cost.

[0006] A cascaded driving system comprises:

[0007] A plurality of motor controller modules and driving motors, each motor controller module being connected with a driving motor;

[0008] The motor controller modules are connected in series;

[0009] The motor controller module comprises a support capacitor and an inverter unit;

[0010] The support capacitor is connected with the positive and negative poles of a direct current power supply respectively, and the support capacitor is connected with the inverter unit in parallel;

[0011] An insulating pad is arranged on the stator of the driving motor, and the rotor of the driving motor adopts an insulating bearing;

[0012] Optionally, the inverter unit comprises:

[0013] Six switching tubes, namely a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a fifth switching tube and a sixth switching tube;

[0014] One end of the supporting capacitor is connected to the collector of the first switch, the collector of the third switch, and the collector of the fifth switch, respectively, and the other end of the supporting capacitor is connected to the emitter of the second switch, the emitter of the fourth switch, and the emitter of the sixth switch, respectively.

[0015] The three phases of the drive motor are respectively connected between the first and second switching transistors, between the third and fourth switching transistors, and between the fifth and sixth switching transistors.

[0016] Optionally, between two adjacent motor controller modules, one motor controller module uses a shielded cable for its connection to the drive motor, while the other motor controller module has an AC filter magnetic ring on its connection to the drive motor.

[0017] Optionally, the switching transistor is an IGBT or a MOSFET.

[0018] Optionally, the motor controller module is further provided with a cooling plate, which is made of insulating material and the cooling medium is cooling oil.

[0019] Optionally, the motor controller module is connected in parallel with a voltage sensor.

[0020] Optionally, insulating bolts may be used when installing the stator of the drive motor.

[0021] A control method for a cascaded drive system, applied to a cascaded drive system, includes:

[0022] Obtain the withstand voltage rating of the motor controller module;

[0023] According to the voltage rating, match the highest withstand voltage of the corresponding supporting capacitor;

[0024] When the voltage of the supporting capacitor exceeds the maximum withstand voltage, the motor controller module is controlled to stop.

[0025] When the voltage of the supporting capacitor is less than the maximum withstand voltage, the capacitor energy of the supporting capacitor is obtained;

[0026] Based on the capacitor energy, the motor speed of the drive motor, and the voltage of the supporting capacitor, the torque control command of the drive motor is obtained.

[0027] A terminal device includes a memory and a processor. The memory stores a computer program that can run on the processor. When the processor loads and executes the computer program, a cascaded drive system control method is used.

[0028] A computer-readable storage medium storing a computer program, wherein when the computer program is loaded and executed by a processor, a cascaded drive system control method is employed.

[0029] The beneficial effects of this invention are:

[0030] 1. Each motor controller module is connected to a drive motor, and the motor controller modules are connected in series. Each motor controller module includes a supporting capacitor and an inverter unit. The two ends of the supporting capacitor are connected to the positive and negative terminals of the DC power supply, respectively. The supporting capacitor and the inverter unit are connected in parallel. The stator of the drive motor is equipped with an insulating pad, and the rotor of the drive motor uses an insulated bearing. This application has the advantage of achieving high-voltage applications using a low-voltage inverter, which has the advantages of lower cost and shorter development cycle compared to products that directly use high-voltage power devices and high-voltage withstand voltage designs.

[0031] 2. Due to insulation requirements, the casings of the two motors cannot be at the same potential. One motor casing is grounded, while the other is suspended. For the motor with its casing grounded, traditional electromagnetic compatibility methods are used. For the motor with its casing suspended, a filter is used to block the common-mode current, thus satisfying both insulation and electromagnetic compatibility requirements. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the single motor drive system structure of the present invention;

[0033] Figure 2 This is a schematic diagram of the cascade mechanism of the two motor drive systems of the present invention;

[0034] Figure 3 This is a schematic diagram of the insulation path between the two motors when the dual stator is electrically connected according to the present invention;

[0035] Figure 4 This is a schematic diagram of the insulation path between two motors when the dual stator is electrically insulated according to the present invention;

[0036] Figure 5 This is a schematic diagram of the structure of the present invention using metal bearings and a reducer;

[0037] Figure 6 This is a schematic diagram of the structure of the present invention using an insulated bearing and a reducer;

[0038] Figure 7 This is a schematic diagram of the insulation path between IGBT chips when the cooling water channel is not insulated according to the present invention;

[0039] Figure 8 This is a schematic diagram of the electromagnetic compatibility structure of the cascaded drive system of the present invention;

[0040] Figure 9This is a schematic diagram of the equivalent circuit of the cascaded drive system of the present invention;

[0041] Figure 10 This is a schematic diagram illustrating the power-energy relationship in a cascaded drive system.

[0042] Figure 11 This is a schematic diagram of the capacitor energy control principle in a cascaded drive system.

[0043] Figure 12 This is a schematic diagram of the control flow of the cascaded drive system of the present invention.

[0044] 1. First motor controller module; 2. First drive motor; 3. First supporting capacitor; 4. Second motor controller module; 5. Second drive motor; 6. Second supporting capacitor; 7. Voltage sensor; 8. Cooling plate; 9. First switching transistor; 10. Second switching transistor; 11. Third switching transistor; 12. Fourth switching transistor; 13. Fifth switching transistor; 14. Sixth switching transistor; 15. Metal bearing; 16. Reducer; 17. Insulated bearing; 18. Shielded cable; 19. AC filter magnetic ring. Detailed Implementation

[0045] A cascaded drive system, such as Figure 1 As shown, it includes:

[0046] Several motor controller modules and drive motors, with each motor controller module connected to one drive motor.

[0047] The motor controller modules are connected in series.

[0048] The motor controller module includes a support capacitor and an inverter unit.

[0049] The two ends of the support capacitor are connected to the positive and negative terminals of the DC power supply, respectively, and the support capacitor is connected in parallel with the inverter unit.

[0050] The stator of the drive motor is equipped with an insulating pad, and the rotor of the drive motor uses an insulating bearing 17.

[0051] The inverter unit includes:

[0052] There are 6 switching transistors, namely the first switching transistor 9, the second switching transistor 10, the third switching transistor 11, the fourth switching transistor 12, the fifth switching transistor 13, and the sixth switching transistor 14.

[0053] One end of the supporting capacitor is connected to the collector of the first switching transistor 9, the collector of the third switching transistor 11, and the collector of the fifth switching transistor 13, respectively. The other end of the supporting capacitor is connected to the emitter of the second switching transistor 10, the emitter of the fourth switching transistor 12, and the emitter of the sixth switching transistor 14, respectively.

[0054] The three phases of the drive motor are respectively connected between the first switch tube 9 and the second switch tube 10, between the third switch tube 11 and the fourth switch tube 12, and between the fifth switch tube 13 and the sixth switch tube 14.

[0055] Between two adjacent motor controller modules, one motor controller module is connected to the drive motor via a shielded cable 18, while the other motor controller module is connected to the drive motor via an AC filter magnetic ring 19.

[0056] The switching transistor is either an IGBT or a MOSFET.

[0057] The motor controller module is also equipped with a cooling plate 8, which is made of insulating material and uses cooling oil as the cooling medium.

[0058] The motor controller module is connected in parallel with voltage sensor 7.

[0059] Insulating bolts are used when installing the stator of the drive motor.

[0060] Specifically, the inverter cascaded drive system can solve the problem of low-voltage inverter power devices (IGBTs or MOSFETs) in high-voltage applications by using series voltage division of supporting capacitors. This application uses two motor controller modules as an example.

[0061] like Figure 2 As shown, the first motor controller module 1 includes a first supporting capacitor 3 and an inverter unit. One end of the first supporting capacitor 3 is connected to the positive terminal of the DC voltage, and the other end of the first supporting capacitor 3 is connected to the second supporting capacitor 6 in the second motor controller module 4. The other end of the second supporting capacitor 6 is connected to the negative terminal of the DC voltage. The first motor controller module 1 is connected to the first drive motor 2, and the second motor controller module 4 is connected to the second drive motor 5. A voltage sensor 7 is connected in parallel between the first motor controller module 1 and the second motor controller 4. Both the first supporting capacitor 3 and the second supporting capacitor 6 are connected in parallel with filter resistors. The connection line between the first motor controller module 1 and the first drive motor 2 is a shielded cable 18. An AC filter magnetic ring 19 is provided on the connection line between the second motor controller module 4 and the second drive motor 5. At this time, the two motor controller modules are cascaded.

[0062] One end of the first supporting capacitor 3 is connected to the collectors of the first switching transistor 9, the third switching transistor 11, and the fifth switching transistor 13, respectively. The other end of the first supporting capacitor 3 is connected to the emitter of the second switching transistor 10, the emitter of the fourth switching transistor 12, and the emitter of the sixth switching transistor 14, respectively. The three phases of the first drive motor 2 are connected between the first switching transistor 9 and the second switching transistor 10, between the third switching transistor 11 and the fourth switching transistor 12, and between the fifth switching transistor 13 and the sixth switching transistor 14, respectively. The connection relationship between the second drive motor 5, the inverter unit, and the second supporting capacitor 6 is exactly the same as the connection relationship between the first motor control module, the first supporting capacitor 3, and the inverter unit.

[0063] According to national standards, when performing insulation withstand voltage tests on a cascaded drive system, the withstand voltage rating of the power devices and motor to the casing is 2*U. DC +1000V, which means that the voltage withstand requirement of the two low-voltage drive systems for the casing is not reduced due to the voltage division by the capacitor.

[0064] Insulating the two low-voltage drive systems is an effective way to solve this problem. This requires that the cascaded inverters and the motor housings be insulated from each other and not at the same potential. However, after the two inverters and the motor are mutually insulated, there are requirements for the electromagnetic compatibility scheme of the drive system.

[0065] The first motor controller module 1 and the first drive motor 2 constitute the first drive system, and the second motor controller module 4 and the second drive motor 5 constitute the second drive system. The grounding points of the first drive system and the second drive system need to be insulated, that is, the stators of the motors need to be insulated from each other, the rotors of the motors need to be insulated from each other, and the controllers need to be insulated from the water-cooled plates.

[0066] If the stators of the first drive motor 2 and the second drive motor 5 are not insulated, and the first motor controller module 1 and the second motor controller simultaneously emit non-vector PWM waves, then both sets of windings of the first drive motor 2 and the second drive motor 5 will be connected to a high-voltage DC voltage; for example, in Figure 3 In the first motor controller module 1, if it is in vector mode, a high DC voltage is applied between the A-phase winding of the first drive motor 2 and the B and C-phase windings of the second drive motor 5. Because the outer casings of these windings are interconnected, the insulation class of the windings should be in accordance with U. DC design.

[0067] If the stators of the first drive motor 2 and the second drive motor 5 are insulated, and both the first motor controller module 1 and the second motor controller module 4 exhibit non-vector behavior, then both sets of windings of the first drive motor 2 and the second drive motor 5 will be connected to a high-voltage DC voltage. For example, in Figure 4In the above scenario, if the first motor controller module 1 and the second motor controller module 4 are in vector mode, a high DC voltage U is applied between the A-phase winding of the first drive motor 2 and the B and C-phase windings of the second drive motor 5. DC Because the outer casings of these winding contacts are mutually insulated, and the resistance of the insulator itself is much greater than that of the internal insulation of the motor, it bears most of the voltage. Therefore, the voltage on the first drive motor 2 and the second drive motor 5 can be ignored. Thus, the insulation class of the windings of the first drive motor 2 and the second drive motor 5 is designed based on the voltage divider, with a value of U. DC / 2, which means the insulation requirement between the first drive motor 2 and the second drive motor 5 is reduced by half. Therefore, insulating pads and insulating bolts are used when installing the drive motor stator.

[0068] However, if the rotors of the first drive motor 2 and the second drive motor 5 are not insulated, such as using Figure 5 In the traditional metal bearing 15 and reducer 16 assembly, the stators of the first drive motor 2 and the second drive motor 5 are connected through the metal bearing 15 and the reducer 16 to form equipotential. Therefore, a high DC voltage is applied between the A-phase winding of the first drive motor 2 and the B and C-phase windings of the second drive motor 5. Because the outer casings of these windings are interconnected, the insulation class of the windings of the first drive motor 2 and the second drive motor 5 is determined according to U... DC design.

[0069] If the rotors of the first drive motor 2 and the second drive motor 5 use insulated bearings 17, or if insulated flanges are used for insulation at the output shaft end, and both the first motor controller module 1 and the second motor controller module 4 exhibit non-vectoring behavior, then both sets of windings of the first drive motor 2 and the second drive motor 5 will be connected to a high-voltage DC voltage. For example, in Figure 6 In the above scenario, if the first motor controller module 1 and the second motor controller module 4 are in vector mode, a high DC voltage is applied between the A-phase winding of the first drive motor 2 and the B and C-phase windings of the second drive motor 5. Because the outer casings in contact with these windings are mutually insulated, the insulation class of the windings can be determined according to U... DC / 2 design.

[0070] The cooling water channels of the first motor controller module 1 and the second motor controller module 4 also need to be insulated from each other. If they are not insulated, problems will arise with the high-voltage tolerance of the IGBT chip in the first motor controller module 1. Figure 7 Taking an example, when the first motor controller module 1 and the second motor controller module 4 are in vector mode, the IGBTs share voltage with each other. If the water-cooled plates are electrically connected, the requirement of the IGBTs on the water-cooled plates is 2*U. DC+1000V; If there is insulation between the water-cooled plates, then the requirements of the IGBTs on the water-cooled plates are U. DC +1000V.

[0071] To achieve insulation between the first and second water-cooled plates, insulating material must be used between the two plates. At the same time, because cooling water is conductive, cooling water cannot be used as the cooling medium; non-conductive cooling oil can be used instead.

[0072] Due to the insulation requirements of the cascaded drive system, the first motor controller module 1 and the second motor controller module 4 cannot have a common grounding point, which results in the electromagnetic insulation scheme of the entire system being different from that of the traditional drive system. Figure 8 For the electromagnetic compatibility solution of this patent, firstly, the Y capacitor of the traditional drive system cannot be used on the DC side; only a DC filter device in the form of a filter magnetic ring can be used. A shielded cable 18 is used between the first motor controller module 1 and the first drive motor 2. The shielding layer of the shielded cable 18 is electrically connected to the housing of the first drive motor 2 and the first motor controller module 1. The housings of the first motor controller module 1 and the first drive motor 2 can be connected to the same ground. However, since the second motor controller module 4 and the second drive motor 5 cannot be electrically connected to the first motor controller module 1 and the second drive motor 5, the second motor controller module 4 and the second drive motor 5 are in a floating state to ground. Therefore, the common-mode current of the second motor controller module 4 can only be filtered by the AC filter magnetic ring 19.

[0073] A control method for a cascaded drive system, applied to a cascaded drive system, includes:

[0074] Obtain the withstand voltage rating of the motor controller module.

[0075] Match the highest withstand voltage of the corresponding supporting capacitor according to the withstand voltage rating.

[0076] When the voltage of the supporting capacitor exceeds the maximum withstand voltage, the motor controller module is stopped.

[0077] When the voltage of the supporting capacitor is less than the maximum withstand voltage, the capacitive energy of the supporting capacitor is obtained.

[0078] Specifically, such as Figure 9 The diagram shown is an equivalent schematic of the cascaded system of this application. Figure 9 In the middle, P mot1 and P mot2 P represents the output power of the first drive motor and the second drive motor, respectively. c1 With P c2 Let E represent the charging power of capacitors C1 and C2, respectively. Under steady state, their value is 0. CLet P1 be the sum of the energy in capacitors C1 and C2, and P1 be the power of the first motor controller. P1 = P c1 +P mot1 P2 is the power of the second motor controller, P2 = P c2 +P mot2 The power mentioned above refers to the DC component of instantaneous power.

[0079] Due to the capacitor current I C1 and I C2 Since the current is alternating current in steady state, the DC components of I1 and I2 are equal, and the following relationship holds:

[0080]

[0081] That is, the voltages of the first supporting capacitor C1 and the second supporting capacitor C2 are proportional to the output power of their respective inverters. Normally, the output power of the two inverters driving the motor is equal, therefore U C1 =U C2 There are also cases where the two inverters drive the motors with different output power. In this case, the voltages across C1 and C2 are:

[0082]

[0083] Among them, U DC It is a DC voltage.

[0084] Therefore, the higher the inverter's output power, the higher the voltage distributed across its corresponding capacitor. In the most extreme case, if one inverter is not working, the capacitor corresponding to the other inverter will bear the entire DC voltage U. DC .

[0085] The maximum voltage distributed across the first supporting capacitor C1 and the second supporting capacitor C2 is determined by the voltage rating of the power devices in the inverter. Based on historical usage data, when using 1200V power devices, the voltage U across the first supporting capacitor is... C1 Or the voltage U of the second supporting capacitor C2 The voltage must not exceed 750V; power devices with a 1700V specification must be used; the first supporting capacitor voltage U C1 Or the voltage U of the second supporting capacitor C2 The voltage cannot exceed 1200V. When the voltage sensor detects that the voltage on both capacitors exceeds the limit, both inverters need to stop working simultaneously.

[0086] The energy in the first supporting capacitor C1 and the second supporting capacitor C2 can be expressed by the following formula:

[0087]

[0088] By maintaining the energy stability of the first supporting capacitor C1 and the second supporting capacitor C2 according to the above formula, U can be achieved. C1 or U C2 Stability. Figure 10 This is a schematic diagram of the power-energy relationship in a cascaded drive system. S in the diagram represents the differential operator. Figure 10 The energy in capacitors C1 and C2 is controlled, and its schematic diagram is shown below. Figure 11 As shown, its control logic is to determine the energy E in capacitor C1. C1 and The difference, if E C1 Less than Then reduce the power P of the first drive motor. mot1 Since power P1 remains constant, therefore power P c1 Increase, the energy E in capacitor C1 C1 Increase. If E C1 Greater than Then increase the power P of the first drive motor. mot1 Since power P1 remains constant, therefore power P c1 The energy E in capacitor C1 decreases. C1 Decrease Let E be the energy of the capacitor in steady state. C2 The control logic is the same.

[0089] Figure 11 The following transfer function can be derived from this:

[0090]

[0091] In the formula k p k is the proportional gain of the PI controller, which is a positive number. i The integral coefficient of the PI controller is positive. The poles in the above equation are always negative; therefore, cascaded systems controlled by this method are always stable.

[0092] When the above control principles are implemented in specific motor control programs, the following situations occur:

[0093] When the torque command and speed of the first drive motor and the second drive motor are respectively T1 * T2 * When the Ω is 1 and the Ω is 2, the voltages across capacitors C1 and C2 in steady state are respectively:

[0094]

[0095] in, The steady-state voltage of capacitor C1, T1 is the steady-state voltage of capacitor C2. * and T2 *Ω1 and Ω2 are the torque commands in steady state, and Ω1 and Ω2 are the speeds in steady state.

[0096] Then, the energies of capacitors C1 and C2 under steady state are respectively:

[0097]

[0098] in, This is the steady-state energy of capacitor C1. Let be the steady-state energy of capacitor C2.

[0099] The torque control command for the drive motor is obtained based on the capacitor energy, the motor speed of the drive motor, and the voltage of the supporting capacitor.

[0100] Specifically, energy control loops are constructed using the energy in capacitors C1 and C2 as control targets, respectively, to control E C1 and E C2 As input, the difference between the input and the actual energy in capacitors C1 and C2 is calculated. This difference is then adjusted using a PI controller. The PI output value is divided by the speeds of the first and second drive motors, and this value is used to compensate for the torque command. Other parts can utilize traditional motor control methods. The final motor control system principle is as follows: Figure 12 As shown. Its control principle can be described as follows: When the energy in capacitors C1 and C2 is higher than the theoretical value, the corresponding first motor controller module and second motor controller module need to output more power, and at that speed, the corresponding torque needs to increase. When the energy in capacitors C1 and C2 is lower than the theoretical value, the corresponding first motor controller module and second motor controller module need to reduce the output power, and at that speed, the corresponding torque needs to decrease.

[0101] This application also discloses a terminal device, including a memory and a processor. The memory stores a computer program that can run on the processor. When the processor loads and executes the computer program, a cascaded drive system control method is used.

[0102] The terminal device can be a computer device such as a desktop computer, a laptop computer, or a cloud server. The terminal device includes, but is not limited to, a processor and a memory. For example, the terminal device may also include input / output devices, network access devices, and buses.

[0103] The processor can be a central processing unit (CPU). Of course, depending on the actual use, it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), off-the-shelf programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc., and this application does not limit it in this regard.

[0104] The memory can be an internal storage unit of the terminal device, such as a hard disk or RAM of the terminal device, or an external storage device of the terminal device, such as a plug-in hard disk, smart memory card (SMC), secure digital card (SD), or flash memory card (FC) equipped on the terminal device. Furthermore, the memory can be a combination of internal storage units and external storage devices of the terminal device. The memory is used to store computer programs and other programs and data required by the terminal device. The memory can also be used to temporarily store data that has been output or will be output. This application does not limit this.

[0105] In this terminal device, a cascaded drive system control method from the above embodiments is stored in the terminal device's memory and loaded and executed on the terminal device's processor for convenient use.

[0106] This application also discloses a computer-readable storage medium, which stores a computer program, wherein when the computer program is executed by a processor, it employs a cascaded drive system control method as described in the above embodiments.

[0107] The computer program can be stored in a computer-readable medium. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or certain middleware. The computer-readable medium includes any entity or device capable of carrying computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the computer-readable medium includes, but is not limited to, the above-mentioned components.

[0108] The cascaded drive system control method described in the above embodiments is stored in the computer-readable storage medium and loaded and executed on the processor to facilitate the storage and application of the above method.

[0109] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0110] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A cascaded drive system, characterized in that, include: Several motor controller modules and drive motors, with each motor controller module connected to one drive motor; The motor controller modules are connected in series; The motor controller module includes a support capacitor and an inverter unit; The two ends of the supporting capacitor are respectively connected to the positive and negative terminals of the DC power supply, and the supporting capacitor is connected in parallel with the inverter unit; The stator of the drive motor is provided with an insulating pad, and the rotor of the drive motor uses an insulating bearing.

2. The cascaded drive system as described in claim 1, characterized in that, The inverter unit includes: There are 6 switching transistors, namely the first switching transistor, the second switching transistor, the third switching transistor, the fourth switching transistor, the fifth switching transistor, and the sixth switching transistor; One end of the supporting capacitor is connected to the collector of the first switch, the collector of the third switch, and the collector of the fifth switch, respectively, and the other end of the supporting capacitor is connected to the emitter of the second switch, the emitter of the fourth switch, and the emitter of the sixth switch, respectively. The three phases of the drive motor are respectively connected between the first and second switching transistors, between the third and fourth switching transistors, and between the fifth and sixth switching transistors.

3. The cascaded drive system as described in claim 1, characterized in that, Between two adjacent motor controller modules, one motor controller module uses a shielded cable for its connection to the drive motor, while the other motor controller module has an AC filter magnetic ring on its connection to the drive motor.

4. The cascaded drive system as described in claim 2, characterized in that, The switching transistor is either an IGBT or a MOSFET.

5. A cascaded drive system as described in claim 1, characterized in that, The motor controller module is also equipped with a cooling plate, which is made of insulating material and the cooling medium is cooling oil.

6. The cascaded drive system as described in claim 1, characterized in that, The motor controller module is connected in parallel with a voltage sensor.

7. A cascaded drive system as described in claim 1, characterized in that, Insulating bolts are used when installing the stator of the drive motor.

8. A control method for a cascaded drive system, applied to a cascaded drive system as described in any one of claims 1-7, characterized in that, include: Obtain the withstand voltage rating of the motor controller module; According to the voltage rating, match the highest withstand voltage of the corresponding supporting capacitor; When the voltage of the supporting capacitor exceeds the maximum withstand voltage, the motor controller module is controlled to stop. When the voltage of the supporting capacitor is less than the maximum withstand voltage, the capacitor energy of the supporting capacitor is obtained; Based on the capacitor energy, the motor speed of the drive motor, and the voltage of the supporting capacitor, the torque control command of the drive motor is obtained.

9. A terminal device, comprising a memory and a processor, characterized in that, The memory stores a computer program that can run on a processor, and when the processor loads and executes the computer program, it employs the method described in claim 8.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is loaded and executed by the processor, the method described in claim 8 is employed.

Images