Dual-motor control circuit, method, and variable frequency speed regulation system

Abstract

The application relates to a dual-motor control circuit, method and variable-frequency speed regulation system. A mode switching module is arranged, so that in the case of common bridge arm failure, the phase connected between the first motor, the second motor and the common bridge arm can be switched to be connected with the bus capacitor bridge arm, so that the inverter topology is converted from five bridge arms to four bridge arms. At this time, the variable-frequency speed regulation system can keep normal operation in the four-bridge-arm mode, and system shutdown caused by common bridge arm failure can be avoided.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a dual-motor control circuit, method, and variable frequency speed control system. Background Technology

[0002] The main problem encountered in the promotion and application of variable frequency speed control systems is the high cost of motor drive systems. Currently, the cost of motor drive systems is mainly reduced by improving the structure of rectifiers and inverters in the motor drive system. For example, typical five-arm inverter topologies and four-arm inverter topologies reduce the number of switching transistors by sharing a common arm, thereby reducing system costs. However, this method makes the common arm more prone to damage. When the common arm is damaged, the system cannot operate and the inverter needs to be replaced, affecting the normal operation of the system. Summary of the Invention

[0003] This application provides a dual-motor control circuit, method, and variable frequency speed control system, aiming to solve the technical problem that the system cannot operate normally when the common bridge arm is damaged in the prior art.

[0004] To solve the aforementioned technical problems, or at least partially solve them, this application provides a dual-motor control circuit. The dual-motor control circuit is connected to a power supply, a first motor, and a second motor, respectively. The dual-motor control circuit includes a rectifier module, a bus capacitor bridge arm, a five-bridge inverter module, and a mode switching module. The power supply is connected to the input terminal of the rectifier module, and the output terminal of the rectifier module is connected to the five-bridge inverter module via the bus capacitor bridge arm. The five-bridge inverter module is connected to the first motor and the second motor. Wherein:

[0005] The five-arm inverter module includes a common arm. The first phase connection terminal of the first motor is connected to the midpoint of the common arm through the mode switching module. The first phase connection terminal of the first motor is also connected to the midpoint of the bus capacitor arm through the mode switching module. The first phase connection terminal of the second motor is connected to the midpoint of the common arm through the mode switching module. The first phase connection terminal of the second motor is also connected to the midpoint of the bus capacitor arm through the mode switching module. Wherein:

[0006] The mode switching module is used to connect the first phase connection terminal of the first motor to the midpoint of the common bridge arm or the midpoint of the bus capacitor bridge arm.

[0007] The mode switching module is used to connect the first phase connection terminal of the second motor to the midpoint of the common bridge arm or the midpoint of the bus capacitor bridge arm.

[0008] Optionally, the mode switching module includes a first circuit breaker, a second circuit breaker, a third circuit breaker, and a fourth circuit breaker, wherein:

[0009] The first phase connection terminal of the first motor is connected to the midpoint of the common bridge arm through the first circuit breaker, and the first phase connection terminal of the first motor is also connected to the midpoint of the bus capacitor bridge arm through the second circuit breaker.

[0010] The first phase connection terminal of the second motor is connected to the midpoint of the common bridge arm through the third circuit breaker, and the first phase connection terminal of the second motor is also connected to the midpoint of the bus capacitor bridge arm through the fourth circuit breaker.

[0011] Optionally, the five-arm inverter module includes five switching arms connected in parallel, each switching arm comprising a first arm, a second arm, a third arm, a fourth arm, and a common arm; wherein:

[0012] The midpoint of the first bridge arm is connected to the second phase connection end of the first motor, and the midpoint of the second bridge arm is connected to the third phase connection end of the first motor.

[0013] The midpoint of the third bridge arm is connected to the second phase connection end of the second motor, and the midpoint of the fourth bridge arm is connected to the third phase connection end of the second motor.

[0014] To achieve the above objectives, this application also provides a dual-motor control method, the method comprising the following steps:

[0015] The dual-motor control method is applied to the dual-motor control circuit described above, and the dual-motor control method includes:

[0016] Obtain the operating status of the first motor, the second motor, and the common bridge arm;

[0017] The target mode of the dual-motor control circuit is determined based on the operating status.

[0018] Send a target signal corresponding to the target mode to the mode switching module so that the mode switching module sets the connection objects of the first phase connection terminal of the first motor and the first phase connection terminal of the second motor to correspond to the target mode.

[0019] Optionally, the step of determining the target mode of the dual-motor control circuit based on the operating state includes:

[0020] The selectable mode is determined based on the operating status of the common bridge arm;

[0021] The target load motor is determined based on the operating status of the first motor and the second motor;

[0022] The target mode corresponding to the target load motor is determined in the optional modes.

[0023] Optionally, determining the selectable mode based on the operating status of the common bridge arm includes:

[0024] Determine whether the operating status of the common bridge arm is in normal operation.

[0025] If the common bridge arm is in normal operating condition, the selectable modes include five-bridge arm mode and single-motor mode;

[0026] If the common bridge arm is in an abnormal operating state, then the optional mode is the four-bridge arm mode.

[0027] Optionally, when the common bridge arm is in normal operating condition, the step of determining the target mode corresponding to the target load motor in the optional modes includes:

[0028] Determine whether the target load motor is a dual-motor or a single-motor motor;

[0029] If the target load motor is a dual-motor type, then the target mode is a five-arm mode;

[0030] If the target load motor is a single motor, then the target mode is a single motor mode.

[0031] Optionally, after the step of determining the target mode of the dual-motor control circuit based on the operating state, the method further includes:

[0032] Match the target modulation scheme corresponding to the target mode;

[0033] A driving signal is generated according to the target modulation scheme;

[0034] The drive signal is sent to the five-bridge inverter module.

[0035] To achieve the above objectives, this application also provides a variable frequency speed control system, characterized in that the variable frequency speed control system includes a first motor, a second motor, a power supply, and a dual-motor control circuit as described above.

[0036] Optionally, the variable frequency speed control system further includes a control chip, the detection terminals of which are respectively connected to the first motor, the second motor, and the common bridge arm, and the output terminal of which is connected to the control terminal of the mode switching module; the control chip includes:

[0037] The first acquisition module is used to acquire the operating status of the first motor, the second motor, and the common bridge arm;

[0038] The first determining module is used to determine the target mode of the dual-motor control circuit based on the operating state.

[0039] The first transmitting module is used to transmit a target signal corresponding to the target mode to the mode switching module, so that the mode switching module sets the connection objects of the first phase connection terminal of the first motor and the first phase connection terminal of the second motor to correspond to the target mode.

[0040] This application proposes a dual-motor control circuit, method, and variable frequency speed control system. By setting a mode switching module, in the event of a common arm failure, the phase connection between the first motor and the second motor and the common arm can be switched to the connection with the bus capacitor arm, thereby changing the inverter topology from five arms to four arms. At this time, the variable frequency speed control system can maintain normal operation in a four-arm configuration, thus avoiding system shutdown due to a common arm failure. Attached Figure Description

[0041] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0042] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0044] Figure 1 This is a schematic diagram of the dual-motor control method of this application;

[0045] Figure 2 This is a schematic diagram of the five-bridge-arm inverter topology of the dual-motor control circuit of this application.

[0046] Figure 3 This is a schematic diagram of the four-bridge arm inverter topology of the dual-motor control circuit of this application.

[0047] Figure 4 This is a schematic diagram of the first motor full-bridge inverter topology of the dual-motor control circuit of this application;

[0048] Figure 5 This is a schematic diagram of the second motor full-bridge inverter topology of the dual-motor control circuit of this application;

[0049] Figure 6 This is a flowchart illustrating an embodiment of the dual-motor control method of this application.

[0050] Explanation of icon numbers:

[0051]

[0052] Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0055] This application provides a dual-motor control circuit, see [link]. Figure 1 The dual-motor control circuit is connected to the power supply ACC, the first motor M1, and the second motor M2, respectively. The dual-motor control circuit includes a rectifier module 100, a bus capacitor bridge arm 200, a five-bridge inverter module 300, and a mode switching module 400. The power supply ACC is connected to the input terminal of the rectifier module 100, and the output terminal of the rectifier module 100 is connected to the five-bridge inverter module 300 via the bus capacitor bridge arm 200. The five-bridge inverter module 300 is connected to the first motor M1 and the second motor M2. Wherein:

[0056] The five-arm inverter module 300 includes a common arm 311. The first phase connection terminal of the first motor M1 is connected to the midpoint of the common arm 311 through the mode switching module 400. The first phase connection terminal of the first motor M1 is also connected to the midpoint of the bus capacitor arm 200 through the mode switching module 400. The first phase connection terminal of the second motor M2 is connected to the midpoint of the common arm 311 through the mode switching module 400. The first phase connection terminal of the second motor M2 is also connected to the midpoint of the bus capacitor arm 200 through the mode switching module 400. Wherein:

[0057] The mode switching module 400 is used to connect the first phase connection terminal of the first motor M1 to the midpoint of the common bridge arm 311 or the midpoint of the bus capacitor bridge arm 200.

[0058] The mode switching module 400 is used to connect the first phase connection terminal of the second motor M2 to the midpoint of the common bridge arm 311 or the midpoint of the bus capacitor bridge arm 200.

[0059] The power supply ACC is an AC power supply. The AC power output by the power supply ACC is rectified by the rectifier module 100 to obtain DC power, and the DC power is used to charge the bus capacitor in the bus capacitor bridge arm 200, thereby providing DC bus voltage through the bus capacitor bridge arm 200. The five-bridge inverter module 300 inverts the DC bus voltage based on the corresponding modulation method to drive the first motor M1 and the second motor M2.

[0060] The mode switching module 400 switches the inverter mode by switching the connection objects of the first phase connection terminals of the first motor M1 and the second motor M2; wherein phase a of the motor is the first phase, phase b is the second phase, and phase c is the third phase; specifically:

[0061] When the first phase connection terminal of the first motor M1 is connected to the midpoint of the common bridge arm 311, and the second phase connection terminal of the first motor M1 is also connected to the midpoint of the common bridge arm 311, the first phase connection terminal of the first motor M1 and the second phase connection terminal of the second motor M2 share the common bridge arm 311. At this time, the inverter form is a five-bridge arm inverter topology.

[0062] When the first phase connection terminal of the first motor M1 is connected to the midpoint of the bus capacitor bridge arm 200, and the second phase connection terminal of the first motor M1 is connected to the midpoint of the bus capacitor bridge arm 200; the first phase connection terminal of the first motor M1 and the second phase connection terminal of the second motor M2 share the bus capacitor bridge arm 200. At this time, the inverter form is a four-bridge-arm inverter topology.

[0063] When the first phase connection terminal of the first motor M1 is connected to the midpoint of the common bridge arm 311, and the second phase connection terminal of the first motor M1 is connected to the midpoint of the bus capacitor bridge arm 200; the inverter form corresponding to the first motor M1 is a voltage-source full-bridge inverter, and the inverter form corresponding to the second motor M2 is a three-phase four-switch inverter.

[0064] When the first phase connection terminal of the first motor M1 is connected to the midpoint of the bus capacitor bridge arm 200, and the second phase connection terminal of the first motor M1 is connected to the midpoint of the common bridge arm 311; the inverter form corresponding to the first motor M1 is a three-phase four-switch inverter, and the inverter form corresponding to the second motor M2 is a voltage-source full-bridge inverter.

[0065] In this embodiment, the mode switching module 400 enables switching between various inverter forms. The five-arm inverter topology has higher bus voltage utilization and higher output power, but it is prone to damage to the common arm 311. When the common arm 311 is damaged, the five-arm inverter topology is destroyed. At this time, the mode switching module 400 converts the inverter form to a four-arm inverter topology. Since the four-arm inverter topology does not include the common arm 311, it can operate normally even when the common arm 311 is damaged, thus ensuring the use of the variable frequency speed control system.

[0066] In this embodiment, by setting a mode switching module 400, the first motor M1 and the second motor M2 can be switched from being connected to the common bridge arm 311 to being connected to the bus capacitor bridge arm 200 in the event of a failure of the common bridge arm 311. This converts the inverter topology from five bridge arms to four bridge arms. At this time, the variable frequency speed control system can maintain normal operation in the form of four bridge arms, thus avoiding system shutdown caused by a failure of the common bridge arm 311.

[0067] Further details will follow. Figure 1 The mode switching module 400 includes a first circuit breaker QF1, a second circuit breaker QF2, a third circuit breaker QF3, and a fourth circuit breaker QF4, wherein:

[0068] The first phase connection terminal of the first motor M1 is connected to the midpoint of the common bridge arm 311 through the first circuit breaker QF1, and the first phase connection terminal of the first motor M1 is also connected to the midpoint of the bus capacitor bridge arm 200 through the second circuit breaker QF2.

[0069] The first phase connection terminal of the second motor M2 is connected to the midpoint of the common bridge arm 311 through the third circuit breaker QF3, and the first phase connection terminal of the second motor M2 is also connected to the midpoint of the bus capacitor bridge arm 200 through the fourth circuit breaker QF4.

[0070] The first circuit breaker QF1 and the second circuit breaker QF2 switch the connection object of the first phase connection terminal of the first motor M1. Specifically, when the first circuit breaker QF1 is open and the second circuit breaker QF2 is closed, the first phase connection terminal of the first motor M1 is connected to the midpoint of the bus capacitor bridge arm 200; when the first circuit breaker QF1 is closed and the second circuit breaker QF2 is open, the first phase connection terminal of the first motor M1 is connected to the midpoint of the common bridge arm 311.

[0071] The third circuit breaker QF3 and the fourth circuit breaker QF4 switch the connection object of the first phase connection terminal of the second motor M2. Specifically, when the third circuit breaker QF3 is open and the fourth circuit breaker QF4 is closed, the first phase connection terminal of the second motor M2 is connected to the midpoint of the bus capacitor bridge arm 200; when the third circuit breaker QF3 is closed and the fourth circuit breaker QF4 is open, the first phase connection terminal of the second motor M2 is connected to the midpoint of the common bridge arm 311.

[0072] It should be noted that this embodiment uses a circuit breaker as an example for illustration, but other switching devices can be selected in actual applications. Since this embodiment is applied to a high-voltage scenario, generally, a high-voltage circuit breaker is used to construct the mode switching module 400 to meet the safety requirements of the circuit.

[0073] Furthermore, the five-arm inverter module 300 includes five switching arms connected in parallel, the switching arms including a first arm 321, a second arm 322, a third arm 323, a fourth arm 324, and a common arm 311; wherein:

[0074] The midpoint of the first bridge arm 321 is connected to the second phase connection end of the first motor M1, and the midpoint of the second bridge arm 322 is connected to the third phase connection end of the first motor M1.

[0075] The midpoint of the third bridge arm 323 is connected to the second phase connection end of the second motor M2, and the midpoint of the fourth bridge arm 324 is connected to the third phase connection end of the second motor M2.

[0076] The common bridge arm 311 and the bus capacitor bridge arm 200 are connected in parallel to each other at the DC end of the rectifier module 100; except for the common bridge arm 311, each switch bridge arm is connected to one and only one phase connection terminal of a motor; at the same time, except for the first phase, the other phase connection terminals of the motor are connected to the midpoint of one switch bridge arm.

[0077] Furthermore, the switch bridge arm includes a first switch S1 and a second switch S2; wherein:

[0078] The drain of the first switch S1 is connected to the positive terminal of the DC bus of the bus capacitor bridge arm 200, the source of the first switch S1 is connected to the drain of the second switch S2, and the source of the second switch S2 is connected to the negative terminal of the DC bus of the bus capacitor bridge arm 200.

[0079] The midpoint of the switch bridge arm is between the source of the first switch S1 and the drain of the second switch S2.

[0080] It is understandable that the gates of the first switch S1 and the second switch S2 are connected to the control chip, and the control chip outputs a drive signal to control the conduction of the first switch S1 and the second switch S2, thereby realizing the inversion of the DC bus voltage.

[0081] The specific types of the first switch S1 and the second switch S2 can be selected based on the actual application needs. In this embodiment, the first switch S1 and the second switch S2 are IGBTs.

[0082] Furthermore, the bus capacitor bridge arm 200 includes a first capacitor C1 and a second capacitor C2; wherein:

[0083] The first terminal of the first capacitor C1 is connected to the positive DC terminal of the rectifier module 100, the second terminal of the first capacitor C1 is connected to the first terminal of the second capacitor C2, and the second terminal of the second capacitor C2 is connected to the negative DC terminal of the rectifier module 100.

[0084] The first end of the first capacitor C1 serves as the positive DC bus of the bus capacitor bridge arm 200, the second end of the second capacitor C2 serves as the negative DC bus of the bus capacitor bridge arm 200, and the midpoint between the second end of the first capacitor C1 and the first end of the second capacitor C2 serves as the midpoint of the bus capacitor bridge arm.

[0085] Understandably, in the case of a five-arm inverter topology, the first capacitor C1 and the second capacitor C2 are equivalent to a bus capacitor; in the case of a four-arm inverter topology, the first capacitor C1 serves as the bus capacitor of the first motor M1, and the second capacitor C2 serves as the bus capacitor of the second motor M2.

[0086] Furthermore, the rectifier module 100 is a rectifier bridge.

[0087] The specific type of rectifier module 100 can be set based on the application scenario and requirements. For example, in this embodiment, it is an uncontrolled rectifier bridge composed of four diodes. The AC terminal of the rectifier bridge is connected to the power supply ACC, and the DC terminal of the rectifier bridge is connected in parallel with the bus capacitor bridge arm 200 and the five-bridge inverter module 300.

[0088] The different inverter forms of the dual-motor control circuit of this application are described below:

[0089] The second phase connection terminal of the first motor M1 is connected to the midpoint of the first bridge arm 321, and the third phase connection terminal of the first motor M1 is connected to the midpoint of the second bridge arm 322; the second phase connection terminal of the second motor M2 is connected to the midpoint of the third bridge arm 323, and the second phase connection terminal of the second motor M2 is connected to the midpoint of the fourth bridge arm 324.

[0090] See Figure 2 , Figure 2 This is a schematic diagram of the five-bridge-arm inverter topology of the dual-motor control circuit of this application.

[0091] The first circuit breaker QF1 and the third circuit breaker QF3 are closed, and the second circuit breaker QF2 and the fourth circuit breaker QF4 are open. At this time, the first phase connection terminal of the first motor M1 is connected to the midpoint of the common bridge arm 311, and the first phase connection terminal of the second motor M2 is connected to the midpoint of the common bridge arm 311. The first capacitor C1 and the second capacitor C2 are equivalent to a bus capacitor. The five-bridge-arm inverter module 300 is controlled based on the modulation method corresponding to the five-bridge-arm inverter topology.

[0092] See Figure 3 , Figure 3 This is a schematic diagram of the four-bridge arm inverter topology of the dual-motor control circuit of this application.

[0093] The first circuit breaker QF1 and the third circuit breaker QF3 are open, and the second circuit breaker QF2 and the fourth circuit breaker QF4 are closed. At this time, the first phase connection terminal of the first motor M1 is connected to the midpoint of the bus capacitor bridge arm 200, and the first phase connection terminal of the second motor M2 is connected to the midpoint of the bus capacitor bridge arm 200. The first capacitor C1 serves as the bus capacitor of the first motor M1, and the second capacitor C2 serves as the bus capacitor of the second motor M2. The first bridge arm 321 to the fourth bridge arm 324 in the five-bridge inverter module 300 are controlled based on the modulation method corresponding to the four-bridge inverter topology.

[0094] See Figure 4 , Figure 4 This is a schematic diagram of the full-bridge inverter topology of the first motor M1 in the dual-motor control circuit of this application;

[0095] The first circuit breaker QF1 and the fourth circuit breaker QF4 are closed, and the second circuit breaker QF2 and the third circuit breaker QF3 are open. At this time, the first phase connection terminal of the first motor M1 is connected to the midpoint of the common bridge arm 311, and the first phase connection terminal of the second motor M2 is connected to the midpoint of the bus capacitor bridge arm 200. The equivalent capacitance of the first capacitor C1 and the second capacitor C2 serves as the bus capacitor of the first motor M1, and the second capacitor C2 serves as the bus capacitor of the second motor M2. The first bridge arm 321, the second bridge arm 322, and the common bridge arm 311 are controlled by the modulation method of the voltage-type full-bridge inverter, and the third bridge arm 323 and the fourth bridge arm 324 are controlled by the modulation method of the three-phase four-switch inverter. The first motor M1 can achieve full power output.

[0096] See Figure 5 , Figure 5 This is a schematic diagram of the full-bridge inverter topology of the second motor M2 in the dual-motor control circuit of this application;

[0097] The first circuit breaker QF1 and the fourth circuit breaker QF4 are open, and the second circuit breaker QF2 and the third circuit breaker QF3 are closed. At this time, the first phase connection terminal of the second motor M2 is connected to the midpoint of the common bridge arm 311, and the first phase connection terminal of the first motor M1 is connected to the midpoint of the bus capacitor bridge arm 200. The equivalent capacitance of the first capacitor C1 and the second capacitor C2 serves as the bus capacitor of the second motor M2, and the first capacitor C1 serves as the bus capacitor of the second motor M2. The third bridge arm 323, the fourth bridge arm 324, and the common bridge arm 311 are controlled by the modulation method of the voltage-source full-bridge inverter, and the first bridge arm 321 and the second bridge arm 322 are controlled by the modulation method of the three-phase four-switch inverter. The second motor M2 can achieve full power output.

[0098] This application provides a dual-motor control method, applied to the aforementioned dual-motor control circuit, with reference to... Figure 6 , Figure 6 This is a flowchart illustrating the first embodiment of the dual-motor control method of this application. The method includes the following steps:

[0099] Obtain the operating status of the first motor, the second motor, and the common bridge arm;

[0100] The target mode of the dual-motor control circuit is determined based on the operating status.

[0101] Send a target signal corresponding to the target mode to the mode switching module so that the mode switching module sets the connection objects of the first phase connection terminal of the first motor and the first phase connection terminal of the second motor to correspond to the target mode.

[0102] The operating status is used to reflect the operating conditions of the first motor, the second motor, and the common bridge arm; for example, the operating status of the motor can include whether the motor is started and the motor's power requirements, while the operating status of the common bridge arm can include whether the common bridge arm is operating normally.

[0103] As can be seen from the foregoing description of the dual-motor control circuit, the dual-motor control circuit can switch between different inverter modes, that is, the dual-motor control circuit has different modes; and the motor conditions and the degree of demand for the common bridge arm are different for different modes. Therefore, the target mode to be set can be determined by the operating status of the first motor, the second motor and the common bridge arm.

[0104] After the target mode is determined, the mode switching module can be adjusted through the corresponding target signal. The connection objects include the midpoint of the common bridge arm and the midpoint of the bus capacitor bridge arm. The target mode can be switched by switching the connection objects of the first phase of the first motor and the first phase of the second motor.

[0105] By setting up a mode switching module, in the event of a common arm failure, the phase connection between the first motor and the second motor and the common arm can be switched to the connection with the bus capacitor arm, thereby changing the inverter topology from five arms to four arms. At this time, the variable frequency speed control system can maintain normal operation in the four-arm mode, which can avoid system shutdown due to common arm failure.

[0106] Furthermore, the step of determining the target mode of the dual-motor control circuit based on the operating state includes:

[0107] The selectable mode is determined based on the operating status of the common bridge arm;

[0108] The target load motor is determined based on the operating status of the first motor and the second motor;

[0109] The target mode corresponding to the target load motor is determined in the optional modes.

[0110] The target load motor is the motor that needs to be driven. It can be understood that the target load motor can be a single motor or a dual motor. In the case of a single motor, the target load motor is either the first motor or the second motor; in the case of a dual motor, the target load motor is either the first motor or the second motor.

[0111] The selectable mode is the mode that can be selected and set under a certain target load motor; it can be understood that the operating status of the common bridge arm determines the number of available switch bridge arms, and therefore, the operating status of the common bridge arm determines the type of mode that can be set, that is, the selectable mode options.

[0112] The target load motor indicates the number of motors that the system needs to drive. Therefore, the target load motor can be used to determine the target mode that best matches the current motor requirements among the available modes.

[0113] Furthermore, determining the selectable mode based on the operating status of the common bridge arm includes:

[0114] Determine whether the operating status of the common bridge arm is in normal operation.

[0115] If the common bridge arm is in normal operating condition, the selectable modes include five-bridge arm mode and single-motor mode;

[0116] If the common bridge arm is in an abnormal operating state, then the optional mode is the four-bridge arm mode.

[0117] When the common bridge arm is in normal operating condition, all five switch bridge arms are considered to be available. Therefore, the five-bridge arm mode and single-motor mode can be implemented. It should be noted that the four-bridge arm mode can also be implemented in this case, but since the five-bridge arm mode can output more power, the five-bridge arm mode is preferred. However, in practical applications, the four-bridge arm mode can be set as an optional mode for the current situation based on actual needs.

[0118] When the common bridge arm is in an abnormal operating state, it is assumed that only the first to fourth bridge arms are available. Therefore, the five-bridge arm mode cannot be implemented. At the same time, since the single-motor mode also uses the common bridge arm, it also cannot be implemented. In this case, the only selectable mode is the four-bridge arm mode. Since the only selectable mode is the four-bridge arm mode, the target mode can be directly set to the four-bridge arm mode.

[0119] Furthermore, when the common bridge arm is in normal operating condition, the step of determining the target mode corresponding to the target load motor in the selectable modes includes:

[0120] Determine whether the target load motor is a dual-motor or a single-motor motor;

[0121] If the target load motor is a dual-motor type, then the target mode is a five-arm mode;

[0122] If the target load motor is a single motor, then the target mode is a single motor mode.

[0123] When the common bridge arm is in normal operating condition, the selectable modes include five-bridge arm mode and single-motor mode. When the target load motor is a dual-motor motor, both the first and second motors need to be driven simultaneously. Therefore, the five-bridge arm mode corresponding to dual-motor drive is adopted. When the target load motor is a single-motor motor, only one motor needs to be driven. Therefore, the single-motor mode corresponding to single-motor drive is adopted.

[0124] Furthermore, after the step of determining the target mode of the dual-motor control circuit based on the operating state, the method further includes:

[0125] Match the target modulation scheme corresponding to the target mode;

[0126] A driving signal is generated according to the target modulation scheme;

[0127] The drive signal is sent to the five-bridge inverter module.

[0128] It is understandable that different inverter types require different modulation methods. In practical applications, different modulation methods can be set for different inverter types. For example, for the five-bridge arm mode, the modulation method can be set to half-cycle SVPWM modulation.

[0129] For the four-arm mode, the modulation method is set to three-phase four-switch SVPWM modulation;

[0130] For single-motor mode, the modulation method of the target load motor is set to the modulation method of the voltage-source full-bridge inverter, and the modulation method of the non-target load motor is set to the modulation method of the three-phase four-switch inverter.

[0131] After determining the target mode, the five-arm inverter module is controlled by matching the target modulation method corresponding to the target mode.

[0132] The overall steps of this application are described below:

[0133] During system startup or operation, the operating status of the first motor, the second motor, and the common bridge arm is acquired; and the target mode is switched in real time based on the operating status; specifically:

[0134] When the common arm is in an abnormal operating state, set the target mode to four-arm mode; specifically:

[0135] The first and third circuit breakers are opened, and the second and fourth circuit breakers are closed. At this time, the first phase connection terminal of the first motor is connected to the midpoint of the bus capacitor bridge arm, and the first phase connection terminal of the second motor is connected to the midpoint of the bus capacitor bridge arm. The first capacitor serves as the bus capacitor of the first motor, and the second capacitor serves as the bus capacitor of the second motor. The first to fourth bridge arms of the five-bridge inverter module are controlled based on the three-phase four-switch SVPWM modulation control.

[0136] When the common arm is in normal operation and both the first and second motors are running, the target mode is set to five-arm mode; specifically:

[0137] The first and third circuit breakers are closed, while the second and fourth circuit breakers are opened. At this time, the first phase connection terminal of the first motor is connected to the midpoint of the common bridge arm, and the first phase connection terminal of the second motor is also connected to the midpoint of the common bridge arm. The first capacitor and the second capacitor are equivalent to a bus capacitor. The five-bridge arm inverter module is controlled based on half-cycle SVPWM modulation.

[0138] When the common bridge arm is in normal operation, and the first motor is running while the second motor is not running, the target mode is set to the single-motor mode of the first motor; specifically:

[0139] The system controls the first and fourth circuit breakers to close, and the second and third circuit breakers to open. At this time, the first phase connection terminal of the first motor is connected to the midpoint of the common bridge arm, and the first phase connection terminal of the second motor is connected to the midpoint of the bus capacitor bridge arm. The equivalent capacitance of the first and second capacitors serves as the bus capacitor of the first motor, and the second capacitor serves as the bus capacitor of the second motor. The first bridge arm, the second bridge arm, and the common bridge arm are controlled by the modulation method of the voltage-source full-bridge inverter, and the third and fourth bridge arms are controlled by the modulation method of the three-phase four-switch inverter. The first motor can achieve full power output.

[0140] When the common bridge arm is in normal operation, and the first motor is not running while the second motor is running, the target mode is set to the single-motor mode of the second motor; specifically:

[0141] The first and fourth circuit breakers are opened, while the second and third circuit breakers are closed. At this time, the first phase connection terminal of the second motor is connected to the midpoint of the common bridge arm, and the first phase connection terminal of the first motor is connected to the midpoint of the bus capacitor bridge arm. The equivalent capacitance of the first and second capacitors serves as the bus capacitor of the second motor, and the first capacitor serves as the bus capacitor of the second motor. The third bridge arm, the fourth bridge arm, and the common bridge arm are controlled by the modulation method of the voltage-source full-bridge inverter, and the first and second bridge arms are controlled by the modulation method of the three-phase four-switch inverter. The second motor can achieve full power output.

[0142] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0143] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0144] This application also provides a variable frequency speed control system, characterized in that the variable frequency speed control system includes a first motor, a second motor, a power supply, and a dual-motor control circuit as described above.

[0145] Furthermore, the variable frequency speed control system also includes a control chip. The detection terminals of the control chip are respectively connected to the first motor, the second motor, and the common bridge arm, and the output terminal of the control chip is connected to the control terminal of the mode switching module. The control chip includes:

[0146] The first acquisition module is used to acquire the operating status of the first motor, the second motor, and the common bridge arm;

[0147] The first determining module is used to determine the target mode of the dual-motor control circuit based on the operating state.

[0148] The first transmitting module is used to transmit a target signal corresponding to the target mode to the mode switching module, so that the mode switching module sets the connection objects of the first phase connection terminal of the first motor and the first phase connection terminal of the second motor to correspond to the target mode.

[0149] Furthermore, the first determining module includes:

[0150] The first determining unit is used to determine the selectable mode based on the operating status of the common bridge arm;

[0151] The second determining unit is used to determine the target load motor based on the operating states of the first motor and the second motor.

[0152] The third determining unit is used to determine the target mode corresponding to the target load motor in the optional modes.

[0153] Further, the first determining unit includes:

[0154] The first judgment subunit is used to determine whether the operating status of the common bridge arm is a normal operating state;

[0155] The first execution subunit is configured to, if the operating state of the common bridge arm is normal operating state, then the selectable modes include five-bridge arm mode and single-motor mode;

[0156] The second execution subunit is configured to select the four-arm mode if the operating state of the common arm is abnormal.

[0157] Further, the second determining unit includes:

[0158] The second judgment subunit is used to determine whether the target load motor is a single motor or a dual motor;

[0159] The third execution subunit is configured to, if the target load motor is a dual motor, then the target mode is a five-arm mode;

[0160] The fourth execution subunit is configured to determine the target mode as a single-motor mode if the target load motor is a single motor.

[0161] Furthermore, the control chip also includes:

[0162] The first matching module is used to match the target modulation scheme corresponding to the target mode;

[0163] The first generation module is used to generate a driving signal according to the target modulation scheme;

[0164] The second transmitting module is used to transmit the drive signal to the five-bridge inverter module.

[0165] It should be noted that the examples and application scenarios implemented by the above modules and corresponding steps are the same, but are not limited to the content disclosed in the above embodiments. It should also be noted that the above modules, as part of the device, can be implemented in software or hardware, wherein the hardware environment includes a network environment.

[0166] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0167] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0168] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0169] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A dual-motor control circuit, characterized in that, The dual-motor control circuit is connected to the power supply, the first motor, and the second motor respectively; the dual-motor control circuit includes a rectifier module, a bus capacitor bridge arm, a five-bridge inverter module, and a mode switching module; the power supply is connected to the input terminal of the rectifier module, the output terminal of the rectifier module is connected to the five-bridge inverter module through the bus capacitor bridge arm, and the five-bridge inverter module is connected to the first motor and the second motor; wherein: The five-arm inverter module includes a common arm. The first phase connection terminal of the first motor is connected to the midpoint of the common arm through the mode switching module. The first phase connection terminal of the first motor is also connected to the midpoint of the bus capacitor arm through the mode switching module. The first phase connection terminal of the second motor is connected to the midpoint of the common arm through the mode switching module. The first phase connection terminal of the second motor is also connected to the midpoint of the bus capacitor arm through the mode switching module. Wherein: The mode switching module is used to connect the first phase connection terminal of the first motor to the midpoint of the common bridge arm or the midpoint of the bus capacitor bridge arm. The mode switching module is used to connect the first phase connection terminal of the second motor to the midpoint of the common bridge arm or the midpoint of the bus capacitor bridge arm. The mode switching module includes a first circuit breaker, a second circuit breaker, a third circuit breaker, and a fourth circuit breaker, wherein: The first phase connection terminal of the first motor is connected to the midpoint of the common bridge arm through the first circuit breaker, and the first phase connection terminal of the first motor is also connected to the midpoint of the bus capacitor bridge arm through the second circuit breaker. The first phase connection terminal of the second motor is connected to the midpoint of the common bridge arm through the third circuit breaker, and the first phase connection terminal of the second motor is also connected to the midpoint of the bus capacitor bridge arm through the fourth circuit breaker. When the first circuit breaker and the fourth circuit breaker are closed, and the second circuit breaker and the third circuit breaker are open, the first motor achieves full power output; When the first circuit breaker and the fourth circuit breaker are open, and the second circuit breaker and the third circuit breaker are closed, the second motor achieves full power output.

2. The dual-motor control circuit as described in claim 1, characterized in that, The five-arm inverter module includes five switching arms connected in parallel, each switching arm comprising a first arm, a second arm, a third arm, a fourth arm, and a common arm; wherein: The midpoint of the first bridge arm is connected to the second phase connection end of the first motor, and the midpoint of the second bridge arm is connected to the third phase connection end of the first motor. The midpoint of the third bridge arm is connected to the second phase connection end of the second motor, and the midpoint of the fourth bridge arm is connected to the third phase connection end of the second motor.

3. A dual-motor control method, characterized in that, The dual-motor control method is applied to the dual-motor control circuit as described in any one of claims 1 to 2, and the dual-motor control method includes: Obtain the operating status of the first motor, the second motor, and the common bridge arm; The target mode of the dual-motor control circuit is determined based on the operating status. Send a target signal corresponding to the target mode to the mode switching module so that the mode switching module sets the connection objects of the first phase connection terminal of the first motor and the first phase connection terminal of the second motor to correspond to the target mode.

4. The dual-motor control method as described in claim 3, characterized in that, The step of determining the target mode of the dual-motor control circuit based on the operating state includes: The selectable mode is determined based on the operating status of the common bridge arm; The target load motor is determined based on the operating status of the first motor and the second motor; The target mode corresponding to the target load motor is determined in the optional modes.

5. The dual-motor control method as described in claim 4, characterized in that, The step of determining the selectable mode based on the operating status of the common bridge arm includes: Determine whether the operating status of the common bridge arm is in normal operation. If the common bridge arm is in normal operating condition, the selectable modes include five-bridge arm mode and single-motor mode; If the common bridge arm is in an abnormal operating state, then the optional mode is the four-bridge arm mode.

6. The dual-motor control method as described in claim 4, characterized in that, When the common bridge arm is in normal operating condition, the step of determining the target mode corresponding to the target load motor in the selectable modes includes: Determine whether the target load motor is a dual-motor or a single-motor motor; If the target load motor is a dual-motor type, then the target mode is a five-arm mode; If the target load motor is a single motor, then the target mode is a single motor mode.

7. The dual-motor control method as described in claim 3, characterized in that, Following the step of determining the target mode of the dual-motor control circuit based on the operating state, the method further includes: Match the target modulation scheme corresponding to the target mode; A driving signal is generated according to the target modulation scheme; The drive signal is sent to the five-bridge inverter module.

8. A variable frequency speed control system, characterized in that, The variable frequency speed control system includes a first motor, a second motor, a power supply, and a dual-motor control circuit as described in any one of claims 1 to 2.

9. The variable frequency speed control system as described in claim 8, characterized in that, The variable frequency speed control system further includes a control chip. The detection terminals of the control chip are connected to the first motor, the second motor, and the common bridge arm, respectively. The output terminal of the control chip is connected to the control terminal of the mode switching module. The control chip includes: The first acquisition module is used to acquire the operating status of the first motor, the second motor, and the common bridge arm; The first determining module is used to determine the target mode of the dual-motor control circuit based on the operating state. The first transmitting module is used to transmit a target signal corresponding to the target mode to the mode switching module, so that the mode switching module sets the connection objects of the first phase connection terminal of the first motor and the first phase connection terminal of the second motor to correspond to the target mode.

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