Drive circuit for variable winding motor and electric drive system including the same

Abstract

The utility model relates to a drive circuit for a variable winding motor, comprising: an inverter circuit, the inverter circuit comprising two groups of inverter bridges, the midpoints of the half bridges in the first inverter bridge are respectively connected to the first end of a corresponding winding in the first group of windings, and the midpoints of the half bridges in the second inverter bridge are respectively connected to the first end of a corresponding winding in the second group of windings; a switch circuit, the switch circuit comprising a plurality of switch elements; and a control unit, the control unit being configured to selectively control the on and off of each bridge arm in the inverter circuit and each switch element in the switch circuit, so that the variable winding motor operates in different working modes. The utility model also relates to an electric drive system comprising the drive circuit. According to the drive circuit of the utility model, the fault tolerance of the topological structure of the motor drive circuit is improved while ensuring the increase of the motor speed regulation range, thereby further improving the safety of the motor control.

Description

Technical Field

[0001] The utility model relates to the field of motors, and more specifically, to a drive circuit for a variable winding motor and an electric drive system comprising the drive circuit. Background Art

[0002] The variable winding motor is an advanced motor type that optimizes the motor's performance by changing the way the motor windings are connected (for example, in series or in parallel) to adapt to different operating conditions. The design of this motor allows high torque at low speeds and high efficiency at high speeds, so this variable winding motor has significant advantages in applications that require a wide speed range and high dynamic performance. For example, in the fields of electric vehicles, wind power generation, and industrial automation, this motor can provide the required flexibility and efficiency.

[0003] For the control of variable winding motors, the existing solution is based on a conventional three-phase bridge inverter, and a switching element is added to the star connection configuration of the motor winding to realize the series or parallel connection of the motor winding. Since the conventional three-phase bridge inverter has only three bridge arms, when any of the bridge arms fails, the motor will not be able to operate normally. With the continuous improvement of motor control safety and fault tolerance requirements, this conventional three-bridge arm inverter can no longer meet the market demand for high fault tolerance application scenarios. Utility Model Content

[0004] The utility model aims to propose a drive circuit for a variable winding motor, which adopts an inverter with a six-bridge arm topology structure and adds a switch group at the motor winding end, so as to improve the fault tolerance of the motor drive circuit topology structure while ensuring that the motor speed regulation range can be increased, thereby further improving the safety of motor control.

[0005] The first aspect of the utility model provides a drive circuit for a variable winding motor, wherein the variable winding motor includes two sets of three-phase windings, and the drive circuit includes:

[0006] An inverter circuit, the inverter circuit comprising two groups of inverter bridges adopting a three-phase half-bridge topology structure, wherein the half-bridge midpoints of each bridge arm in the first inverter bridge are respectively connected to the first end of a corresponding one of the first windings of the two groups of three-phase windings, and the half-bridge midpoints of each bridge arm in the second inverter bridge are respectively connected to the first end of a corresponding one of the second windings of the two groups of three-phase windings;

[0007] a switching circuit including a plurality of switching elements configured to electrically connect the first group of windings and the second group of windings to each other in different connection modes; and

[0008] A control unit is configured to selectively control the on and off of each bridge arm in the inverter circuit and each switch element in the switch circuit so that the variable winding motor operates in different working modes.

[0009] According to an optional embodiment, the switch circuit includes:

[0010] at least one first switching element for connecting a second end of a corresponding one of the first set of windings to a first neutral point;

[0011] at least one second switching element for connecting a first end of a corresponding one of the second set of windings to a second end of a corresponding one of the first set of windings; and

[0012] A third switching element is used to connect the first neutral point to a second neutral point, wherein the second neutral point is connected to a second end of a corresponding one of the second group of windings.

[0013] According to an optional embodiment, the at least one first switching element, the at least one second switching element and the third switching element are selected from the group consisting of a MOS tube, a BJT tube, an IGBT tube and a thyristor.

[0014] According to an optional embodiment, the first inverter bridge and the second inverter bridge are respectively connected between a positive DC bus and a negative DC bus of a DC power supply.

[0015] According to an optional embodiment, the first group of windings includes a first winding, a second winding and a third winding in a star connection configuration, and the second group of windings includes a fourth winding, a fifth winding and a sixth winding in a star connection configuration.

[0016] According to an optional embodiment, the first group of windings and the second group of windings are electrically connected to each other in parallel or in series.

[0017] According to an optional embodiment, the first inverter bridge is composed of three first upper bridge arms and three first lower bridge arms, and the second inverter bridge is composed of three second upper bridge arms and three second lower bridge arms.

[0018] According to an alternative embodiment, the control unit forms part of a motor controller.

[0019] The second aspect of the utility model further proposes an electric drive system with a variable winding. According to an optional embodiment, the electric drive system includes:

[0020] A motor comprising two sets of three-phase windings; and

[0021] A drive circuit for a variable winding motor as described above.

[0022] According to an optional embodiment, the motor is a permanent magnet synchronous motor.

[0023] Compared with conventional variable winding motor control strategies, the drive circuit of the utility model has the following advantages:

[0024] - Improved motor output torque in low speed range: In low speed range, motors usually require larger torque to overcome inertia force during startup. The topological structure of the utility model can increase current when needed by switching between series and parallel of each winding of the motor, thereby providing greater torque output. This is particularly important for application scenarios such as vehicle startup and climbing, especially it can reduce vehicle startup time and improve the overall operating efficiency of the vehicle;

[0025] - Reduced back EMF in high speed area: When running at high speed, the back EMF of the motor will increase, which may cause the current to decrease, thus affecting the performance of the motor. By optimizing the topology of the motor drive circuit, the impact of the motor back EMF can be reduced at high speeds, and the current can be kept stable, thus ensuring that the motor can still maintain high efficiency and stability when running at high speeds;

[0026] - Able to achieve a wider speed range: The speed range of a motor refers to the range in which the motor can stably operate at different speeds. The drive circuit topology structure of the utility model enables the motor to operate in a wider speed range through optimization in the low speed and high speed areas, which is of great significance for applications requiring a wide speed ratio; and

[0027] - Improved fault tolerance of motor control: The fault tolerance of motor control refers to the ability of the system to maintain its function when some components fail. According to the drive circuit topology of the utility model, by designing redundant paths, the motor can continue to operate even when some bridge arms fail. This design greatly improves the reliability of the motor in the face of sudden failures, which not only improves the safety of the motor, but also reduces downtime and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] By incorporating the accompanying drawings and Figure 1 With reference to the specific implementation modes used to illustrate certain principles of the present invention, other features and advantages of the method of the present invention will become clear or be described in more detail.

[0029] Figure 1 A topological diagram of a conventional driving circuit for controlling a variable winding motor is shown.

[0030] Figure 2 A topological structure diagram of a driving circuit for controlling a variable winding motor according to a first exemplary embodiment of the present utility model is shown.

[0031] Figure 3 Shows Figure 2 Schematic diagram of the control strategy of the drive circuit in the first working mode shown in FIG.

[0032] Figure 4 Shows Figure 2 Schematic diagram of the control strategy of the drive circuit in the second working mode shown in FIG.

[0033] Figure 5 Shows Figure 2 Schematic diagram of the control strategy of the drive circuit in the third working mode shown in .

[0034] Figure 6 Shows Figure 2 Schematic diagram of the control strategy of the drive circuit in the fourth working mode shown in .

[0035] Figure 7 Shows Figure 2 Schematic diagram of the control strategy of the drive circuit in the fifth working mode shown in .

[0036] Figure 8 The simulation results of the motor output driven by the driving circuit according to the present invention are shown. DETAILED DESCRIPTION

[0037] The drive circuit for a variable winding motor according to the utility model will be described below with reference to the accompanying drawings and by way of example. In the following description, many specific details are set forth so that those skilled in the art can more fully understand the utility model. However, it is obvious to those skilled in the art that the utility model may be implemented without some of these specific details. On the contrary, it is contemplated that the utility model may be implemented with any combination of the following features and elements, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments and advantages are for illustrative purposes only and should not be regarded as elements or limitations of the claims.

[0038] Figure 1 FIG. 1 shows a topological structure diagram of a conventional drive circuit for controlling a variable winding motor. Figure 1 As shown in , the motor includes two groups of three-phase windings, namely the first group of windings U, V, W and the second group of windings X, Y, Z. The driving circuit of the motor still adopts a conventional three-bridge arm inverter (i.e., a three-phase half-bridge inverter). In order to realize different connection modes between the windings U, V, W and X, Y, Z in the motor, switch groups S1-S9 are added.

[0039] from Figure 1 It can be seen that when switches S4-S6 are turned on and switches S1-S3 and S7-S9 are turned off, the two groups of windings are connected in series, that is, winding U and winding X are connected in series, winding V and winding Y are connected in series, and winding W and winding Z are connected in series. On the contrary, when switches S1-S3 and S7-S9 are turned on and switches S4-S6 are turned off, the two groups of windings U / X, V / Y, W / Z are connected in parallel.

[0040] Figure 1 The drive circuit shown in the embodiment uses a switch group to realize the series and parallel switching between the two sets of three-phase windings of the motor, thereby increasing the speed regulation range of the motor. However, with the continuous improvement of the requirements for motor control safety and fault tolerance, when any bridge arm in the inverter fails, this drive mode will cause the motor to fail to operate normally, so this drive circuit cannot meet the requirements of high fault tolerance application scenarios.

[0041] To this end, the utility model proposes a new drive circuit for a variable winding motor. The drive circuit adopts an inverter with a six-bridge arm topology structure and adds a switch group at the motor winding end. This can improve the fault tolerance of the motor drive circuit topology structure while ensuring that the motor speed regulation range can be increased, thereby further improving the safety of motor control.

[0042] Figure 2 The topological structure diagram of the drive circuit for controlling a variable winding motor according to the first exemplary embodiment of the utility model is shown. The variable winding motor can be, for example, a permanent magnet synchronous motor (abbreviated as "PMSM") having two sets of three-phase windings. Specifically, the motor may include a first set (three-phase) windings U, V, W and a second set (three-phase) windings X, Y, Z, and the two sets of windings are respectively in a star connection configuration.

[0043] The driving circuit in this embodiment particularly includes an inverter circuit for driving a motor. The inverter circuit may include two groups of inverter bridges adopting a three-phase half-bridge topology structure, namely, a first inverter bridge and a second inverter bridge. The two inverter bridges are respectively connected between the positive DC bus and the negative DC bus of the DC power supply, and are used to convert the DC voltage from the DC power supply into an AC voltage for driving each phase winding of the motor.

[0044] See also Figure 2The first inverter bridge is composed of three first upper bridge arms Q1, Q3, Q5 and three first lower bridge arms Q2, Q4, Q6, and the second inverter bridge is composed of three second upper bridge arms Q7, Q9, Q11 and three second lower bridge arms Q8, Q10, Q12. The midpoints of the half bridges of each bridge arm Q1-Q6 in the first inverter bridge are respectively connected to the first end of a corresponding winding in the first winding group U, V, W of the two three-phase windings, and the midpoints of the half bridges of each bridge arm Q7-Q12 in the second inverter bridge are respectively connected to the first end of a corresponding winding in the second winding group X, Y, Z of the two three-phase windings.

[0045] In order to realize different connection modes (e.g., series connection or parallel connection) between the first winding group U, V, W and the second winding group X, Y, Z in the motor, the drive circuit may further include a switch circuit, which includes a plurality of switch elements. The switch elements may be controlled by the control unit ( Figure 2 The first winding group U, V, W and the second winding group X, Y, Z are electrically connected to each other in different connection modes under the control of the inverter circuit (not shown). Here, the control unit may form a part of the motor controller, which may be configured to selectively control the on and off of each bridge arm Q1-Q12 in the inverter circuit and each switching element Q13-Q19 in the switch circuit, so that the motor operates in different working modes.

[0046] Specifically, the switch circuit includes at least one first switch element Q13-Q15, at least one second switch element Q16-Q18 and a third switch element Q19, and these switch elements can be any one selected from MOS tubes, BJT tubes, IGBT tubes and thyristors. This article takes N-channel MOS tubes as an example to introduce the operation of these switch elements in detail.

[0047] Among them, the first switching elements Q13-Q15 are used to connect the second end of a corresponding one of the first windings U, V, W to the first neutral point. The second switching elements Q16-Q18 are used to connect the first end of a corresponding one of the second windings X, Y, Z to the second end of a corresponding one of the first windings U, V, W. The third switching element Q19 is used to connect the first neutral point to the second neutral point, wherein the second neutral point is directly connected to the second end of a corresponding one of the second windings X, Y, Z. The use of the third switching element Q19 in this topology can achieve reliable freewheeling when the two windings are operated in series.

[0048] The following is a detailed introduction Figure 2 The control strategy for controlling the drive circuit of a variable winding motor in different operating modes is shown in FIG.

[0049] Figure 3 Shows Figure 2Schematic diagram of the control strategy of the drive circuit in the first working mode. Figure 3 In this mode, it is assumed that the switch elements Q16-Q18 are turned on, while the switch elements Q13-Q15 and Q19 are turned off (such as Figure 3 In this case, the two windings U / X, V / Y, and W / Z are electrically connected in series. At this time, the motor is equivalent to a conventional three-phase motor, and the control unit can disable each bridge arm Q7 to Q12 in the second inverter bridge (i.e., Figure 3 As shown by the light grey lines in the middle, Q7-Q12 are all turned off), so that the three-phase control of the motor can be achieved by using only the first inverter bridge Q1-Q6.

[0050] Figure 4 Shows Figure 2 Schematic diagram of the control strategy of the drive circuit in the second working mode. Figure 4 In this mode, it is assumed that the switch elements Q13-Q15 and Q19 are turned on, while the switch elements Q16-Q18 are turned off (such as Figure 4 In this case, the two windings U / X, V / Y, and W / Z are electrically connected to each other in parallel. At this time, the motor is equivalent to two three-phase motors connected in parallel, and the control unit can use the first inverter bridge Q1-Q6 and the second inverter bridge Q7-Q12 to realize synchronous control of the two three-phase motors.

[0051] Figure 5 Shows Figure 2 Schematic diagram of the control strategy of the drive circuit in the third working mode. Figure 5 In this mode, assuming that any one of the six bridge arms (U, V, W, X, Y, and Z phase bridge arms) of the drive circuit fails, for example, taking the failure of the U phase bridge arm as an example, the remaining five bridge arms (V, W, X, Y, and Z phase bridge arms) can still be used to continue to realize the three-phase asymmetric operation of the motor.

[0052] Figure 6 Shows Figure 2 Schematic diagram of the control strategy of the drive circuit in the fourth working mode. Figure 6 In this mode, assuming that any two of the six bridge arms (U, V, W, X, Y, and Z phase bridge arms) of the drive circuit fail, for example, taking the failure of the U-phase and V-phase bridge arms as an example, the remaining four bridge arms (W, X, Y, and Z phase bridge arms) can still be used to continue to achieve the three-phase asymmetric operation of the motor.

[0053] Figure 7 Shows Figure 2 Schematic diagram of the control strategy of the drive circuit in the fifth working mode. Figure 7In this mode, assuming that any three of the six bridge arms (U, V, W, X, Y, and Z phase bridge arms) of the drive circuit fail, for example, taking the failure of the U-phase, V-phase, and W-phase bridge arms as an example, the remaining three bridge arms (X, Y, and Z phase bridge arms) can still be used to continue to achieve three-phase symmetrical and stable operation of the motor.

[0054] Although Figure 5 It is shown that in the case of a U-phase fault, the remaining five bridge arms are used to realize the three-phase asymmetric operation of the motor. However, it can be understood that in the case of the U-phase fault, the three-phase symmetrical operation of the motor can also be realized by making the U, V, W phase windings and their corresponding inverter bridges (Q1-Q6) all fail (as shown in FIG. Figure 7 Similarly, although Figure 6 It is shown that in the case of U and V phase failure, the remaining four bridge arms are used to realize the three-phase asymmetric operation of the motor. However, it can be understood that in the case of U and V phase failure, the three-phase symmetrical operation of the motor can also be realized by making the U, V, and W phase windings and their corresponding inverter bridges (Q1-Q6) all fail (such as Figure 7 ).

[0055] Figure 8 The simulation results of the motor output driven by the driving circuit according to the present invention are shown. The simulation results depict the torque-speed characteristic curve of the variable winding motor driven by the driving circuit according to the present invention, such as Figure 8 As shown in FIG. 1 , the motor output includes two torque-speed characteristic curves, corresponding to the two sets of windings in the motor being connected in series (such as Figure 3 ) and in parallel (as shown in Figure 4 The output result of the case where the motor is connected as shown in FIG. 1 is shown in FIG. 1 . It can be seen from the simulation results that the motor has a wider speed range than the conventional three-phase motor.

[0056] An exemplary embodiment of the utility model further proposes an electric drive system with a variable winding, characterized in that the electric drive system comprises a motor, the motor comprises two sets of three-phase windings; and the drive circuit for the variable winding motor as described above. The motor can be a permanent magnet synchronous motor with a variable winding.

[0057] According to the drive circuit for a variable winding motor using the topological structure of the utility model, not only the performance of the variable winding motor is improved, but also the reliability and safety of the motor under various operating conditions are enhanced, so that it has a wide range of application prospects in industrial and commercial applications. In particular, the drive circuit enables the motor to operate stably within a wider speed range and has a strong fault redundancy capability, which enables the motor to better adapt to different working environments and load changes, and improves the versatility and flexibility of the motor. In addition, the energy conversion efficiency of the motor is optimized throughout the operating range, which means that at the same input power, the motor can provide more output power, or at the same output power, the motor has lower energy consumption, which has a positive impact on energy conservation, emission reduction and reducing operating costs.

[0058] It can be understood by those skilled in the art that, in the present utility model, terms such as "comprising" and "including" indicate that in addition to the steps directly and clearly stated in the specification and claims, the technical solution of the present application does not exclude the situation of having other steps that are not directly or clearly stated. Although the present utility model has been disclosed as above with preferred embodiments, the present utility model is not limited thereto. Any changes and modifications made by any person skilled in the art without departing from the spirit and scope of the present utility model should be included in the protection scope of the present utility model, and therefore the protection scope of the present utility model should be based on the scope defined by the claims.

Claims

1. A drive circuit for a variable winding motor, the variable winding motor comprising two sets of three-phase windings, characterized in that: The driving circuit comprises: An inverter circuit, the inverter circuit comprising two groups of inverter bridges adopting a three-phase half-bridge topology structure, wherein the half-bridge midpoints of each bridge arm (Q1-Q6) in the first inverter bridge are respectively connected to the first end of a corresponding one of the first groups of windings (U, V, W) of the two groups of three-phase windings, and the half-bridge midpoints of each bridge arm (Q7-Q12) in the second inverter bridge are respectively connected to the first end of a corresponding one of the second groups of windings (X, Y, Z) of the two groups of three-phase windings; a switching circuit, the switching circuit comprising a plurality of switching elements, the plurality of switching elements being configured to electrically connect the first group of windings (U, V, W) and the second group of windings (X, Y, Z) to each other in different connection modes; and A control unit is configured to selectively control the on and off of each bridge arm in the inverter circuit and each switch element in the switch circuit so that the variable winding motor operates in different working modes.

2. The drive circuit for a variable winding motor according to claim 1, characterized in that: The switch circuit comprises: at least one first switching element (Q13-Q15), the at least one first switching element (Q13-Q15) being used to connect the second end of a corresponding one of the first group of windings (U, V, W) to a first neutral point; at least one second switching element (Q16-Q18), the at least one second switching element (Q16-Q18) being used to connect a first end of a corresponding one of the second group of windings (X, Y, Z) to a second end of a corresponding one of the first group of windings (U, V, W); and A third switching element (Q19) is used to connect the first neutral point to a second neutral point, wherein the second neutral point is connected to a second end of a corresponding one of the second group of windings (X, Y, Z).

3. The drive circuit for a variable winding motor according to claim 2, characterized in that: The at least one first switch element (Q13-Q15), the at least one second switch element (Q16-Q18) and the third switch element (Q19) are selected from the group consisting of MOS tubes, BJT tubes, IGBT tubes and thyristors.

4. The drive circuit for a variable winding motor according to any one of claims 1 to 3, characterized in that: The first inverter bridge and the second inverter bridge are respectively connected between a positive DC bus and a negative DC bus of a DC power supply.

5. The drive circuit for a variable winding motor according to any one of claims 1 to 3, characterized in that: The first group of windings (U, V, W) includes a first winding (U), a second winding (V) and a third winding (W) in a star connection configuration, and the second group of windings (X, Y, Z) includes a fourth winding (Z), a fifth winding (Y) and a sixth winding (Z) in a star connection configuration.

6. The drive circuit for a variable winding motor according to any one of claims 1 to 3, characterized in that: The first group of windings (U, V, W) and the second group of windings (X, Y, Z) are electrically connected to each other in parallel or in series.

7. The drive circuit for a variable winding motor according to any one of claims 1 to 3, characterized in that: The first inverter bridge is composed of three first upper bridge arms (Q1, Q3, Q5) and three first lower bridge arms (Q2, Q4, Q6), and the second inverter bridge is composed of three second upper bridge arms (Q7, Q9, Q11) and three second lower bridge arms (Q8, Q10, Q12).

8. The drive circuit for a variable winding motor according to any one of claims 1 to 3, characterized in that: The control unit forms part of a motor controller.

9. An electric drive system with a variable winding, characterized in that: The electric drive system includes: A motor comprising two sets of three-phase windings; and A drive circuit for a variable winding motor according to any one of claims 1 to 8.

10. The electric drive system according to claim 9, characterized in that: The motor is a permanent magnet synchronous motor.

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