Motor vector control device, vehicle-mounted thermal management system and current ripple suppression method

Abstract

The invention relates to a motor vector control device based on a multi-motor system, a vehicle-mounted thermal management system comprising the motor vector control device, and a method for suppressing bus current ripples of the multi-motor system by using the motor vector control device. The motor vector control device comprises: a power supply configured to supply power to a main control chip in the device; at least two drive circuits, wherein each drive circuit is arranged between the direct current bus and a corresponding motor in the at least two motors; the main control chip is connected to the control ends of the at least two driving circuits and is configured to adjust the output torque of each motor in a space vector pulse width modulation mode, and the main control chip is further configured to adjust the output torque of each motor in a single modulation period. The zero vector position of each motor is adjusted to ensure that the effective vector of each motor falls into different interval ranges.

Description

Technical Field

[0001] This disclosure relates to the field of motor control, and more specifically, to a motor vector control device based on a multi-motor system, an on-board thermal management system including the device, and a method for using the motor vector control device to suppress bus current ripple in a multi-motor system. Background Technology

[0002] In vehicle thermal management systems, various actuators (such as water pumps, water valves, expansion valves, and fans) play a crucial role. These actuators are divided into intelligent and non-intelligent types. Intelligent actuators have built-in controllers and receive commands from the thermal management system via a communication bus. However, this configuration means that each actuator requires a separate controller, resulting in higher costs.

[0003] To reduce costs, the new electrical architecture's thermal management system adopts a strategy of integrating the actuator control section, reducing the actuator to a non-intelligent type, retaining only the motor and mechanical structure. This design simplifies the system but requires the thermal management system to provide stable power filtering to drive multiple motors.

[0004] These actuators typically include multiple high-power water pumps and fans, which can lead to problems such as excessive bus current and overheating of filter capacitors when the thermal management system controls multiple motors simultaneously. To address these issues, the thermal management system usually uses large-capacity capacitors and inductors for filtering, but this results in increased filter size and cost.

[0005] Therefore, there is an urgent need to provide a solution that can effectively suppress the problem of large current (i.e., current ripple) in multi-motor systems. Summary of the Invention

[0006] To address the problem of excessive current ripple in existing multi-motor systems, this disclosure proposes a novel motor vector control device. This device does not require altering the original PWM carrier wave in the motor controller; instead, it suppresses capacitor ripple current in multiple motors within a single interrupt routine by employing different voltage modulation methods. Specifically, this disclosure uses Space Vector Pulse Width Modulation (SVPWM). By adjusting the positions of the zero vectors V0(0,0,0) and V7(1,1,1) of different motors within the PWM cycle, the effective operating vectors of different motors are evenly distributed within a single PWM cycle without overlap. This method maintains the original duration of the effective voltage vector while preventing multiple motors from maximizing their current simultaneously by adjusting the position of the zero vectors, thereby effectively reducing bus current ripple.

[0007] The first aspect of this disclosure provides a motor vector control device based on a multi-motor system, the multi-motor system including at least two motors connected to a DC bus, the device comprising:

[0008] A power supply configured to supply power to the main control chip in the device;

[0009] At least two drive circuits, each drive circuit being disposed between the DC bus and a corresponding motor of the at least two motors; and

[0010] A main control chip is connected to the control terminals of the at least two drive circuits and configured to adjust the output torque of each motor in a space vector pulse width modulation manner. The main control chip is further configured to ensure that the effective vector of each motor falls within a different range by adjusting the zero vector position of each motor within a single modulation cycle.

[0011] According to an optional embodiment, the main control chip is further configured to measure the three-phase current of a corresponding motor when the corresponding motor of the at least two motors is at zero vector, so as to adjust the output torque of each motor in real time based on the measurement result.

[0012] According to an optional embodiment, the at least two motors include a first motor, a second motor, and a third motor, and the single modulation period includes a first interval, a second interval, and a third interval, wherein the main control chip is further configured as follows:

[0013] Within the first interval, the voltage vector of the first motor is made to be an effective vector, and the voltage vectors of the second and third motors are made to be zero vectors;

[0014] Within the second interval, the voltage vector of the second motor is made to be an effective vector, and the voltage vectors of the first and third motors are made to be zero vectors; and

[0015] Within the third interval, the voltage vector of the third motor is made to be an effective vector, and the voltage vectors of the first and second motors are made to be zero vectors.

[0016] According to an optional embodiment, the main control chip is further configured to keep the phase of the carrier signal of each motor synchronized during the space vector pulse width modulation process.

[0017] According to an optional embodiment, the at least two motors are three-phase motors, and the at least two drive circuits include eight operating states, each operating state corresponding to a corresponding voltage vector of the three-phase motor.

[0018] According to an optional embodiment, the voltage vector of the three-phase motor includes six effective vectors and two zero vectors.

[0019] A second aspect of this disclosure also proposes an on-board thermal management system, which includes the motor vector control device described above.

[0020] A third aspect of this disclosure also proposes a method for suppressing bus current ripple in a multi-motor system using the motor vector control device described above. The method includes the following steps: within a single modulation cycle, adjusting the zero vector position of each motor to ensure that the effective vector of each motor falls within a different range, thereby suppressing the bus current ripple of the multi-motor system.

[0021] The motor vector control device disclosed herein not only effectively solves the current ripple problem in multi-motor systems, but also simplifies hardware configuration, reduces costs, and improves system stability and reliability. Its specific advantages include:

[0022] - To reduce the current ripple of the bus capacitor, this device achieves a uniform distribution of the effective working vector by modulating the position of the zero vector, thereby significantly reducing the ripple of the bus current. Test results show that the capacitor ripple current is reduced by 60% to 75%.

[0023] - Simplifies the hardware requirements of the circuit. This device uses a PWM carrier in phase and can be used with a single interrupt handler, reducing hardware resource requirements, making it suitable for most MCUs and lowering system costs; and

[0024] - Improve system stability. This device helps reduce the heating of the filter capacitor by reducing current ripple, thereby improving the stability and lifespan of multi-motor systems. Attached Figure Description

[0025] By incorporating the figures in this article and subsequently the accompanying figures Figure 1 The specific embodiments used to illustrate certain principles of this disclosure will make other features and advantages of the methods of this disclosure clearer or more specifically explained.

[0026] Figure 1 The diagram illustrates the working principle of a conventional current ripple suppression method for multi-motor systems.

[0027] Figure 2 A voltage vector diagram is shown in the SVPWM modulation method based on a three-phase full-bridge inverter bridge structure.

[0028] Figure 3 A schematic diagram of the voltage modulation waveform of the motor vector control device according to the present disclosure is shown.

[0029] Figure 4 A comparison chart showing the test results of the motor vector control device based on a multi-motor system disclosed herein compared to existing multi-motor system control schemes is presented. Detailed Implementation

[0030] The motor vector control device based on a multi-motor system according to the present disclosure will now be described with reference to the accompanying drawings and embodiments. In the following description, numerous specific details are set forth to enable those skilled in the art to gain a more complete understanding of the present disclosure. However, it will be apparent to those skilled in the art that implementations of the present disclosure may not include some of these specific details. Instead, the present disclosure may be practiced 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 construed as elements or limitations of the claims.

[0031] Currently, carrier phase-shifting technology is commonly used to suppress current ripple in multi-motor systems. This technology separates the effective vector and zero vector of the motor voltage by adjusting the phase of the PWM carrier curve, allowing the positive and negative currents generated by different motor controllers to cancel each other out, thereby effectively reducing capacitor ripple current.

[0032] Figure 1 A schematic diagram illustrating the working principle of a conventional current ripple suppression method for multi-motor systems is shown. Figure 1 As shown, a multi-motor system is assumed to contain two motors for driving different actuators (e.g., a water pump and a fan). For different controllers of these two motors, a 90-degree phase difference is created between the two motor carriers by modulating the carrier phase, thereby canceling out the current ripples Ic1 and Ic2 generated by the two motors, ultimately reducing the total ripple current Ic_sum on the bus (i.e., the current ripple flowing through the bus capacitor).

[0033] However, this existing current ripple suppression scheme has certain limitations. In particular, it requires separate control of the carrier signals for different motors, and current acquisition relies on the carrier triggered by a PWM interrupt, typically triggering ADC sampling at the zero or apex of the carrier. When using carrier phase-shifting technology, independent ADC sampling and interrupt routines need to be configured for each motor. This not only places high demands on hardware resources but also makes efficient control difficult to achieve when microcontroller unit (MCU) resources are limited. To execute the control of multiple motors within the same interrupt routine, the carrier PWM of each motor needs to be kept synchronized.

[0034] To meet the control requirements of the thermal management system for multiple motors, the existing current ripple suppression scheme needs to be improved.

[0035] To address the problem of excessive current ripple in existing multi-motor systems, this disclosure proposes a novel motor vector control device. This device does not require altering the original PWM carrier wave in the motor controller; instead, it suppresses capacitor ripple current in multiple motors within a single interrupt routine by employing different voltage modulation methods. Specifically, this disclosure uses Space Vector Pulse Width Modulation (SVPWM). By adjusting the positions of the zero vectors V0(0,0,0) and V7(1,1,1) of different motors within the PWM cycle, the effective operating vectors of different motors are evenly distributed within a single PWM cycle without overlap. This method maintains the original duration of the effective voltage vector while preventing multiple motors from maximizing their current simultaneously by adjusting the position of the zero vectors, thereby effectively reducing bus current ripple.

[0036] Figure 2 The voltage vector diagram in the SVPWM modulation method based on a three-phase full-bridge inverter bridge structure is shown. In SVPWM (Space Vector Pulse Width Modulation), the six switching devices of the three-phase full-bridge inverter can be combined to form eight different switching states, corresponding to eight vectors in the voltage space. Two of these states can be represented by three binary numbers, such as V0(0,0,0) and V7(1,1,1). These two states do not generate effective current in motor drive and are therefore called zero vectors. The other six states, such as V1(0,0,1), V2(0,1,0), V3(0,1,1), V4(1,0,0), V5(1,0,1), and V6(1,1,0), constitute six effective vectors, which are evenly distributed in the voltage space, with each pair of vectors forming a 60-degree sector.

[0037] By synthesizing these effective and zero vectors, any vector within 360 degrees can be generated. When synthesizing a particular vector, it can be decomposed into the two closest fundamental vectors, and then the desired vector can be synthesized by adjusting the application time of these two vectors. This method not only ensures that the generated voltage waveform approximates a sine wave, but also achieves efficient control of the motor through precise control of the application time. For example, in Figure 2 In the vector V2(0,1,0), it means that in sector 2, the U-phase voltage of the motor is zero, the V-phase voltage is at its maximum, and the W-phase voltage is zero.

[0038] This disclosure aims to address the capacitor ripple current problem in thermal management controllers of existing multi-motor systems using SVPWM technology. In automotive thermal management systems, the controller needs to drive multiple motors simultaneously, such as water pumps and fans. These motors have high power, leading to significant bus current ripple during control. Ripple current not only increases system energy consumption but can also cause overheating of filter capacitors, affecting system stability and lifespan. Existing solutions typically employ carrier phase shifting to suppress ripple current, but this requires multiple independent ADC sampling and interrupt routines, placing high demands on hardware resources and proving difficult to implement with limited microcontroller unit (MCU) resources.

[0039] To address this, this disclosure proposes a motor vector control device utilizing SVPWM technology, which enables precise control of multi-motor systems, effectively suppresses bus current ripple, and improves system stability and efficiency. The device specifically includes a power supply, at least two drive circuits, and a main control chip. This device is particularly useful for controlling multi-motor systems within vehicles, especially those comprising at least two motors connected to a DC bus. The power supply provides the necessary electrical energy to the entire device (especially the main control chip). The drive circuits are positioned between the DC bus and a corresponding motor among the at least two motors, responsible for converting the electrical energy provided by the power supply into a form suitable for the operation of each motor and adjusting the motor's output torque according to the instructions of the main control chip.

[0040] The main control chip is the core of this vector control device. It uses Space Vector Pulse Width Modulation (SVPWM) technology to precisely control the output torque of at least two motors connected to the DC bus. During the implementation of SVPWM, the main control chip can cleverly adjust the zero vector position of each motor to ensure that the effective vector of each motor falls within a different range within a single modulation cycle. This control strategy not only maintains the original duration of the effective voltage vector but also avoids the simultaneous maximization of current in multiple motors by adjusting the position of the zero vector, effectively reducing the ripple of the bus current.

[0041] In this zero-vector state, the current freewheels inside the motor. No current flows through the DC bus capacitor, and the motor phase currents are relatively stable, allowing for the acquisition of the motor's three-phase current. When one motor in the system is in a zero-vector state, the main control chip can measure the motor's three-phase current in real time and dynamically adjust the output torque based on the measurement results to optimize the overall system performance.

[0042] During this space vector pulse width modulation process, the main control chip ensures that the carrier signal phase of each motor remains synchronized. This not only improves control accuracy but also enhances system stability.

[0043] Figure 3A schematic diagram of the voltage modulation waveform of a motor vector control device according to this disclosure is shown. Assuming the device is used to control three motors, in... Figure 3 In the diagram, the red, green, and blue lines on the left represent the PWM outputs of the three-phase voltages UVW of the three motors, which are combined into a unit vector. The right side shows the PWM carrier wave and bus current waveforms of the three motors, respectively. Taking sector 1 as an example, the corresponding effective working vectors are U4(1,0,0) and U6(1,1,0).

[0044] As referenced above Figure 1 Taking the three-phase modulation process as an example, U0(0,0,0) and V7(1,1,1) are zero vectors, while other combinations V1(0,0,1), V2(0,1,0), V3(0,1,1), V4(1,0,0), V5(1,0,1), and V6(1,1,0) are effective working vectors. Within one PWM cycle, the effective working vector's duration is kept constant while the zero vector position is modified. This modulation method does not affect the motor phase voltage output. By modulating the zero vector position, the position of the effective working vector is adjusted to avoid the ripple currents Ic1, Ic2, and Ic3 of the three motors simultaneously reaching their maximum, thereby reducing the total ripple of the bus current, Ic_sum.

[0045] like Figure 3 As shown, for three FOC motors, assuming the zero vectors of the first motor are V0(0,0,0) and V7(1,1,1), the effective voltage vector of the second motor is concentrated in the range of approximately 25% and 75% of the modulation period. The zero vector of the second motor is V0(0,0,0), and the effective voltage vector of the second motor is concentrated in the range of approximately 50% of the modulation period. The zero vector of the third motor is V7(1,1,1), and the effective voltage vector of the third motor is concentrated in the range of approximately 0% and 100%.

[0046] Furthermore, this disclosure also provides an on-board thermal management system that integrates the aforementioned motor vector control device, providing a more stable and efficient solution for vehicle thermal management. Due to the use of this innovative vector control device, the on-board thermal management system not only improves the efficiency and stability of motor control but also significantly reduces the overall energy consumption and heat loss of multi-motor systems, thus enhancing the thermal management performance of multi-motor systems.

[0047] According to another embodiment, this disclosure also proposes a method for suppressing bus current ripple in a multi-motor system using the above-mentioned motor vector control device. The method is characterized in that, within a single modulation cycle, the effective vector of each motor is ensured to fall within a different range by adjusting the zero vector position of each motor, thereby suppressing the bus current ripple of the multi-motor system.

[0048] Figure 4 A comparison chart of test results is shown between the motor vector control device based on a multi-motor system of this disclosure and existing multi-motor system control schemes. The test conditions are assumed to be a 10kHz carrier frequency. Figure 4 The blue waveform curve I_cap2 represents the test results using existing multi-motor system control schemes, while the orange waveform curve I_cap1 represents the test results using the motor vector modulation scheme of this disclosure. Figure 4 As can be seen, the modulation strategy disclosed herein can significantly suppress the ripple current of the bus capacitor, especially reducing the ripple current of the bus capacitor by 60% to 75%.

[0049] According to the motor vector control device disclosed herein, it achieves a uniform distribution of the effective working vector within the PWM cycle without altering the original PWM carrier wave, by innovatively using different zero-vector injection methods. Specifically, the device adjusts the positions of the zero vectors U0(0,0,0) and V7(1,1,1) of each motor, thereby adjusting the position of the effective voltage vector and reducing the overall bus current ripple. Furthermore, since this disclosure uses a PWM carrier wave with the same phase, the current sampling process is simplified. Current sampling and interrupt processing for all motors can be completed at the zero and vertices of the carrier wave, requiring only one interrupt routine. This design is applicable to most existing microcontroller units.

[0050] Those skilled in the art will understand that the steps of the method according to this disclosure are not limited to being performed in the order listed above. Furthermore, in this disclosure, terms such as "comprising" and "including" indicate that, in addition to steps that are directly and explicitly stated in the specification and claims, the technical solution of this application does not exclude the presence of other steps not directly or explicitly stated.

[0051] While this disclosure has been described above with reference to preferred embodiments, it is not limited thereto. Any modifications and alterations made by those skilled in the art without departing from the spirit and scope of this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope defined in the claims.

Claims

1. A motor vector control device based on a multi-motor system, wherein the multi-motor system includes at least two motors connected to a DC bus, characterized in that, The device includes: A power supply configured to supply power to the main control chip in the device; At least two drive circuits, each drive circuit being disposed between the DC bus and a corresponding motor of the at least two motors; and A main control chip is connected to the control terminals of the at least two drive circuits and configured to adjust the output torque of each motor in a space vector pulse width modulation manner. The main control chip is further configured to ensure that the effective vector of each motor falls within a different range by adjusting the zero vector position of each motor within a single modulation cycle.

2. The motor vector control device according to claim 1, characterized in that, The main control chip is further configured to measure the three-phase current of a corresponding motor when the corresponding motor of the at least two motors is at zero vector, so as to adjust the output torque of each motor in real time based on the measurement result.

3. The motor vector control device according to claim 1 or 2, characterized in that, The at least two motors include a first motor, a second motor, and a third motor, and the single modulation period includes a first interval, a second interval, and a third interval, wherein the main control chip is further configured as follows: Within the first interval, the voltage vector of the first motor is made to be an effective vector, and the voltage vectors of the second and third motors are made to be zero vectors; Within the second interval, the voltage vector of the second motor is made to be an effective vector, and the voltage vectors of the first and third motors are made to be zero vectors; and Within the third interval, the voltage vector of the third motor is made to be an effective vector, and the voltage vectors of the first and second motors are made to be zero vectors.

4. The motor vector control device according to claim 1 or 2, characterized in that, The main control chip is further configured to keep the phase of the carrier signal of each motor synchronized during the space vector pulse width modulation process.

5. The motor vector control device according to claim 1 or 2, characterized in that, The at least two motors are three-phase motors, and the at least two drive circuits include eight operating states, each operating state corresponding to a voltage vector of the three-phase motor.

6. The motor vector control device according to claim 5, characterized in that, The voltage vector of the three-phase motor includes six effective vectors and two zero vectors.

7. A vehicle-mounted thermal management system, characterized in that, The system includes a motor vector control device according to any one of claims 1 to 6.

8. A method for suppressing bus current ripple in a multi-motor system using a motor vector control device according to any one of claims 1 to 6, characterized in that, The method includes the following steps: within a single modulation cycle, by adjusting the zero vector position of each motor to ensure that the effective vector of each motor falls within a different range, thereby suppressing the bus current ripple of the multi-motor system.

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