Control apparatus for driving three-phase motor, and electromechanical system

Abstract

The present invention relates to a control apparatus for driving a three-phase motor and an electromechanical system. The control apparatus comprises a three-phase inverter bridge, a short-circuit detection unit and a controller. The short-circuit detection unit is configured to detect whether each bridge arm is short-circuited. The controller is configured to perform the following steps: step S20, if it is detected that one of the bridge arms is short-circuited, according to the short-circuited bridge arm, determining an available zone (AZ), an operable zone (OZ) and a stop zone (SZ), which are divided on the basis of voltage space vectors; step S30, calculating a desired voltage vector Ue; step S40, determining a zone determined in step S20 where the desired voltage vector Ue is located; and S50, according to the zone where the desired voltage vector Ue is located, controlling a power switch element of a bridge circuit. The electromechanical system comprises a three-phase motor and the described control apparatus configured to drive the three-phase motor.

Description

Control device and electromechanical system for driving three-phase motor Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a control device for driving a three-phase motor and an electromechanical system comprising the control device. Background Art

[0002] Currently, motors such as brushless DC motors (BLDC) and permanent magnet synchronous motors (PMSM) are widely used as power sources in many fields requiring low torque ripple or high power density, including vehicles and other industrial fields.

[0003] Brushless DC motors and permanent magnet synchronous motors are typically driven by at least one three-phase bridge inverter circuit, which primarily includes six power switching elements, such as metal oxide semiconductor field effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). However, power switching elements withstand high voltages, high currents, and high temperatures when driving the motor, resulting in a higher failure rate than other electronic components, sometimes as high as 60% to 70% failure rate, making them the weak point of the entire system.

[0004] In current solutions, once a short-circuit fault is detected in a MOSFET or IGBT, the typical strategy is to stop driving the three-phase bridge inverter circuit, thereby stopping driving the motor to prevent the fault from spreading. At this point, the motor stops working and the system loses its functionality.

[0005] For some fail-safe applications, certain functions must still be executed even when a fault occurs. In this case, the motor will be reversed by other power sources, such as human power or hydraulics, to rotate. For example, in an electronic power steering (EPS) system, if the power switch shorts and the electronic power assist is lost, the motor will be reversed when the driver manually turns the steering wheel. Another example is a brake assist system where the power switch shorts and the electronic power assist is lost, and the motor will be reversed when the driver applies the brakes.

[0006] In such applications, the controller stops driving the inverter circuit during a fault condition, and the reverse-drag motor will operate in generator mode, generating back electromotive force (BEMF). When the motor rotor enters a specific angle range, the BEMF will induce current in the current path formed by the short-circuited power switching element, the body diode of other MOSFETs, or the freewheeling diode of other IGBTs, thereby generating a resistive torque that resists the external power source, thereby hindering or even blocking the system function. Specifically, in the aforementioned ESP application, the driver will find it very difficult to rotate the steering wheel, requiring more force than pure manual steering. The same is true for the application of brake assist systems, where pressing the brake pedal will be more difficult than without brake assist.

[0007] To address these shortcomings, common solutions include adding two or three additional power switching elements to disconnect the motor phase nodes from the bridge inverter drive, or using relays to disconnect the motor windings' star connection, thereby eliminating the BEMF current path. However, the addition of additional electronic components increases system cost and reduces reliability. Furthermore, the additional power switching elements generate more heat during operation, wasting energy and reducing efficiency. Furthermore, more electronic components occupy more PCB area, increasing system size.

[0008] Summary of the Invention

[0009] Therefore, the object of the present invention is to provide a control device for driving a three-phase motor, by means of which the electromechanical system can continue to perform some functions when the power switching devices in the three-phase bridge inverter circuit are short-circuited, especially in "fail-oriented safe state" applications.

[0010] According to one aspect of the present invention, the above object is achieved by a control device for driving a three-phase motor. The control device includes: a three-phase inverter bridge, a short-circuit detection unit, and a controller.

[0011] The three-phase inverter bridge includes three bridge paths, each bridge path includes a bridge arm between a voltage source node and a phase node and a bridge arm between the phase node and a reference node, and each bridge arm includes a power switching element.

[0012] The short circuit detection unit is configured to perform the steps:

[0013] Step S10: Detect whether each bridge arm is short-circuited.

[0014] The controller is configured to perform the following steps:

[0015] Step S20, if a short circuit is detected in one of the bridge arms, determining an operational area, an operable area, and a stop area divided based on the voltage space vector according to the short-circuited bridge arm;

[0016] Step S30, calculating the expected voltage vector Ue;

[0017] Step S40, determining the area where the expected voltage vector Ue is located, which is determined in step S20;

[0018] Step S50 : controlling the power switching elements of the bridge circuit according to the region where the expected voltage vector Ue is located.

[0019] Advantageously, step 50, controlling the power switching elements of the bridge circuit according to the region where the expected voltage vector Ue is located, includes executing the following steps:

[0020] Step S51: If the desired voltage vector Ue is in the operable region, the power switching elements of the bridge circuit are controlled according to the condition that the bridge arm is not short-circuited, so as to provide the desired voltage vector Ue;

[0021] Step S52: If the desired voltage vector Ue is in the operable region, the power switching elements of the bridge circuit are controlled so that the basic voltage vector Ue is located in the operable region and has the smallest angle with the desired voltage vector Ue. e,1～6 Provide expected voltage vector Ue separately;

[0022] Step S53: If the expected voltage vector Ue is in the stop region, the control bridge is stopped.

[0023] Advantageously, in step S52, the controller performs the steps:

[0024] Step S521, determine the basic voltage vector U that provides the desired voltage vector Ue e,1～6 The direction of the desired voltage vector Ue and the basic voltage vector U e,1～6 The angle θ between them;

[0025] Step S522: Calculate the basic voltage vector U according to the following formula: e,1～6 Amplitude:

[0026] U e,1～6 =Ue / cosθ.

[0027] Advantageously, in step S52, the controller further performs the steps of:

[0028] Step S523: The calculated basic voltage vector U e,1～6 The amplitude and threshold value U of the basic voltage vector t,1～6 For comparison, if the expected basic voltage vector U e,1～6 The magnitude is greater than the threshold Ut,1～6 , then the basic voltage vector U e,1～6 The amplitude is limited to the threshold U t,1～6 .

[0029] Advantageously, the threshold value U of the basic voltage vector t,1～6 It is set according to the controller's supply voltage, the controller's maximum output current, the controller and motor's temperature limits, and the motor's field-weakening current limits.

[0030] Advantageously, after executing step S50 , the controller re-executes step S30 and subsequent steps.

[0031] Advantageously, under the control logic of the three bridges in the three-phase inverter bridge working simultaneously, the range of the operable region is [U base -60°,U base +60°], the range of the operable area is (U base +60°,U base +150°)∪(U base -150°,U base -60°), the range of the stop area is the remaining angle range of the voltage space vector diagram excluding the runnable area and the operable area, where U base It is a basic voltage vector corresponding to the following bridge arm conduction state: in the bridge circuit where the short-circuited bridge arm is located, the short-circuited bridge arm is in the conduction state, and in the other two bridge circuits among the three bridge circuits, the bridge arms opposite to the short-circuited bridge arm are in the conduction state.

[0032] Advantageously, under the control logic in which only two bridges in the three-phase inverter bridge work simultaneously, the range of the operable region is [U base -60°,U base +60°], the range of the operable area is (U base +60°,U base +120°)∪(U base -120°,U base -60°), the range of the stop zone (SZ) is the remaining angle range of the voltage space vector diagram excluding the runnable area and the operable area, where U base It is a basic voltage vector corresponding to the following bridge arm conduction state: in the bridge circuit where the short-circuited bridge arm is located, the short-circuited bridge arm is in the conduction state, and in the other two bridge circuits among the three bridge circuits, the bridge arms opposite to the short-circuited bridge arm are in the conduction state.

[0033] According to another aspect of the present invention, the aforementioned object is achieved by an electromechanical system comprising a three-phase motor and a control device according to the aforementioned embodiment, wherein the control device is configured to drive the three-phase motor.

[0034] Advantageously, the electromechanical system is an electric power steering system for a vehicle or a drive system for driving the vehicle.

[0035] Advantageously, the electromechanical system comprises an actuating member for driving the rotor of the three-phase motor in rotation by means of an external force.

[0036] According to the present invention, a control device for driving a three-phase motor includes only basic components. During normal operation of the electromechanical system, the control device continuously monitors the power switching elements for short-circuit faults. Once a short-circuit detection unit detects that one of the bridge arms has shorted, for example due to a short-circuit fault in a power switching element, the electromechanical system enters a "limp home" mode. Specifically, in this "limp home" mode, the control device, particularly the controller, utilizes the remaining five normally functioning power switching elements to control the motor to continue providing torque based on the rotor angle. This maintains control of the motor, rather than shutting it down directly, allowing the electromechanical system to continue performing some functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Features, advantages, and technical effects of exemplary embodiments will be described below with reference to the accompanying drawings.

[0038] FIG1 is a schematic diagram of a control device and a motor driven by the control device according to an embodiment of the present invention;

[0039] FIG2 shows a control method performed by a control device according to an embodiment of the present invention;

[0040] FIG3 shows a voltage space vector diagram under a motor control logic;

[0041] FIG4 shows a case where, under the control logic involved in FIG3 , the operating region, the operable region, and the stop region divided based on the voltage space vector are determined according to the short-circuited bridge arm;

[0042] FIG5 shows sub-steps according to step S52 of FIG2 ;

[0043] FIG6 is a schematic diagram showing a desired voltage vector Ue when the operable region is determined based on the sub-steps shown in FIG5 ;

[0044] FIG7 shows a voltage space vector diagram under another motor control logic;

[0045] FIG8 shows a situation in which, under the control logic involved in FIG7 , the operating area, the operable area, and the stop area divided based on the voltage space vector are determined according to the short-circuited bridge arm. DETAILED DESCRIPTION

[0046] FIG1 shows a schematic diagram of a control device and a motor driven by the control device according to one embodiment of the present invention.

[0047] The control device shown here and the electric motor it drives can be used in an electromechanical system.

[0048] The electromechanical system may be an electronic power-assist system for a vehicle, also known as an i-Boost system. Specifically, the electronic power-assist system includes, but is not limited to, a brake assist system, a pedal force compensation system, an ABS anti-lock braking system, and a power steering system.

[0049] The electromechanical system can also be a drive system used to propel a vehicle. Here, the drive system is used to provide propulsion for an electric or hybrid vehicle. The motor in the electromechanical system can be a belt-driven starter / generator (BSG) in position P0 or a motor in any of positions P1 through P4.

[0050] Electromechanical systems can also be used in other industrial fields. For example, electromechanical systems are water pumps.

[0051] As shown in FIG1 , the control device for driving a three-phase motor M includes a three-phase inverter bridge, a short-circuit detection unit (not shown), and a controller.

[0052] The three-phase inverter bridge includes three bridge paths, or phases A, B, and C. Each bridge path A, B, and C includes a bridge arm between a voltage source node and a phase node coupled to a three-phase motor M, also known as a high-voltage-side bridge arm or upper bridge arm. Each bridge path A, B, and C also includes a bridge arm between that phase node and a reference node, also known as a low-voltage-side bridge arm or lower bridge arm. Each upper bridge arm and each lower bridge arm includes a power switching element. Preferably, the power switching element is a MOSFET or an IGBT.

[0053] The short-circuit detection unit is configured to detect whether each bridge arm is short-circuited. A short-circuit detection device can be installed between the voltage source node and the phase node, and between the phase node and the reference node, of each bridge circuit A, B, or C to detect whether each bridge arm is short-circuited. Since bridge arm short-circuit failures are most likely caused by short-circuited power switching elements, it is also possible to consider installing the short-circuit detection device so that it measures whether the two ends of each power switching element are short-circuited.

[0054] The controller here uses control methods such as SPWM (Sinusoidal Pulse Width Modulation), SVPWM (Space Vector Pulse Width Modulation), and DPWM (Discontinuous Pulse Width Modulation) to control the switching elements of the three-phase inverter bridge, thereby converting DC power into AC power to drive the three-phase motor.

[0055] Here, the control device for driving the three-phase motor M comprises only basic components. According to the present invention, the control device continuously monitors the power switching elements for short-circuit faults during normal operation of the electromechanical system. Once the short-circuit detection unit detects that one of the bridge arms has shorted, for example due to a short-circuit fault in a power switching element, the electromechanical system enters a "limp home" mode. Specifically, in this "limp home" mode, the control device, particularly the controller, utilizes the remaining five normally functioning power switching elements to control the motor to continue providing torque based on the rotor angle, thereby maintaining control of the motor rather than shutting it down.

[0056] FIG2 shows a control method for controlling a device to enter a “limp home” mode and executed in the mode, the control method comprising the steps of:

[0057] Step S10, the short circuit detection unit detects whether each bridge arm is short-circuited;

[0058] Step S20 , if a short circuit is detected in one of the bridge arms, the controller determines an operative area AZ, an operable area OZ, and a stop area SZ divided based on the voltage space vector according to the short-circuited bridge arm;

[0059] Step S30, the controller calculates the expected voltage vector Ue;

[0060] Step S40, the controller determines the area where the expected voltage vector Ue is located, which is determined in step S20;

[0061] In step S50, the controller performs the following steps according to the region where the expected voltage vector Ue is located:

[0062] Step S51: If the desired voltage vector Ue is in the operable area AZ, the power switching elements of the bridge circuit are controlled according to the condition that the bridge arm is not short-circuited to provide the desired voltage vector Ue;

[0063] Step S52: If the desired voltage vector Ue is in the operable region OZ, the power switching elements of the bridge circuit are controlled so that the basic voltage vector Ue is located in the operable region AZ and has the smallest angle with the desired voltage vector Ue. e,1～6 Provide expected voltage vector Ue separately;

[0064] Step S53: If the desired voltage vector Ue is in the stop zone (SZ), the control bridge is stopped.

[0065] Here, the division of the operative range AZ, the operable range OZ, and the stationary range SZ (step 20) and the calculation of the desired voltage vector Ue (step 30) are both based on the voltage space vector in the field of motor control. The resulting relationship of the voltage space vector corresponds to the switching function of the bridge arm, especially the power switching element.

[0066] For a three-phase inverter circuit, only one arm of each phase (bridge) is turned on at any one time, so a switching function Sx (x = a, b, c) can be defined. When the upper arm is on and the lower arm is off, Sx = 1; when the lower arm is on and the upper arm is off, Sx = 0. If the upper and lower arms of different phases (bridges) are turned on simultaneously, a phase current is generated, resulting in a non-zero vector. If the upper arms of all three phases (bridges) are turned on simultaneously, or if the lower arms of all three phases (bridges) are turned on simultaneously, no phase current is generated, resulting in a zero vector.

[0067] The following description will be made with reference to the voltage space vector diagram in a motor drive control mode shown in FIG3 .

[0068] In the motor drive control method corresponding to Figure 3, when the control device is operating normally, the controller controls the three bridges in the three-phase inverter bridge to operate simultaneously. At any given moment, the upper arm of one of the three bridges is connected and the lower arms of the other two bridges are connected, or the lower arm of one of the three bridges is connected and the upper arms of the other two bridges are connected. This type of motor drive control method is particularly suitable for field-oriented control (FOC) or direct torque control (DTC), for example, for permanent magnet synchronous motors.

[0069] Taking magnetic field oriented control as an example, combined with Figure 1, we can see that there are a total of 8 basic voltage vectors as shown in Table 1, including: 6 non-zero vectors U1 (001), U2 (010), U3 (011), U4 (100), U5 (101), U6 (110) and two zero vectors U0 (000) and U7 (111). The non-zero vectors have the same amplitude, both 2 / 3Udc, and adjacent vectors are separated by 60°. The two zero vectors have an amplitude of 0 and are located in the center.

[0070] Table 1: Voltage space vector table

[0071] As can be seen, the voltage space vector diagram shown in Figure 3 contains eight voltage space vectors U0-U7 and six sectors I-VI, each of which occupies an angular range of 60°. In each sector, two adjacent voltage vectors and the zero vector are selected and synthesized according to the volt-second balance principle to form an arbitrary voltage vector for each sector.

[0072] For step S20, in the control mode where the three bridges in the three-phase inverter bridge work simultaneously, the range of the operable area AZ is [U base -60°,U base +60°], the range of the operating area OZ is (U base +60°,U base +150°)∪(U base -150°,U base -60°), the range of the stop zone SZ is the remaining angle range of the voltage space vector diagram excluding the runnable zone AZ and the operable zone OZ. base is the basic voltage vector corresponding to the following bridge arm conduction states: in the bridge circuit where the short-circuited bridge arm is located, the short-circuited bridge arm is in the conduction state; and in the other two bridge circuits, the bridge arms opposite to the short-circuited bridge arm are in the conduction state. It should be noted that the upper bridge arm and the lower bridge arm are opposite to each other, or in other words, for the upper bridge arm, its opposite bridge arm is the lower bridge arm, and for the lower arm, its opposite bridge arm is the upper bridge arm.

[0073] FIG4 shows a case where the operating area, the operable area, and the stop area are determined based on the voltage space vector according to the short-circuited bridge arm under the control method described in FIG3 , that is, the case where the lower bridge arm of bridge A is short-circuited. Here, the basic voltage vector U3 (011) corresponding to the case where the lower bridge arm of bridge A is in the conducting state, the upper bridge arm of bridge B is in the conducting state, and the upper bridge arm of bridge C is in the conducting state is U base At this time, the controller can realize the basic voltage vectors U0, U2, U3 and U1 by controlling the other five normally operating power switching devices. In this case, as shown in FIG4 , the operable area AZ is represented by a sector indicated by a grid, and the range of the operable area AZ is [U base -60°,U base +60°], that is, [U2, U1]. As shown in FIG4 , the operable area OZ is represented by a dotted sector. The range of the operable area OZ is (U base +60°,U base +150°)∪(U base -150°,U base-60°), that is, (U2-90°, U2) ∪ (U1, U1+90°). The range of the stop zone SZ is the remaining angular range of the voltage space vector diagram excluding the runnable zone AZ and the operable zone OZ, that is, [U1+90°, U2-90°].

[0074] Similarly, the operating area, the operable area, and the stop area can be divided when other bridge arms are short-circuited. base When the upper arm of bridge B is short-circuited, U2(010) is used as U base When the lower arm of bridge B is short-circuited, U5(101) is used as U base When the upper arm of bridge C is short-circuited, U1(001) is used as U base When the lower arm of bridge C is short-circuited, U6(110) is used as U base .

[0075] The steps of the control method shown in FIG. 2 will be further described below with reference to the situation shown in FIG. 4 , ie, the situation where the lower arm of the bridge A is short-circuited.

[0076] For step S30, the expected voltage vector Ue is calculated based on the current rotor angle of the motor. In this case, it is understood that the electromechanical system or the control device should also include a detection unit for directly or indirectly measuring the rotor angle.

[0077] Subsequently, referring to step S40 in FIG. 2 , the controller determines the area determined in step S20 where the desired voltage vector Ue is located, that is, determines in which area of ​​the operative area AZ, the operable area OZ, and the stop area SZ the desired voltage vector Ue is located.

[0078] In the subsequent step S50 , the controller executes different steps S51 , S52 or S53 according to the judgment result of step S40 , that is, the region where the expected voltage vector Ue is located.

[0079] Step S51 is applicable to the case where the desired voltage vector Ue is in the operable region AZ. In this case, the basic voltage vector Ue used to synthesize the desired voltage vector Ue is e,1～6 All are located in the operating area AZ. At this time, the power switching elements of the bridge circuit are controlled according to the condition that the bridge arm is not short-circuited to provide the desired voltage vector Ue. In the example shown in Figure 4, the desired voltage vector Ue is in the operable area AZ, that is, within the range of [U2, U1]. At this time, the basic voltage vector U used to provide the desired voltage vector Ue is e,2 、U e,3 and / or U e,1This can be achieved by controlling the normally operating power switching devices. Specifically, if the desired voltage vector Ue is within the range of [U2, U3], the basic voltage vector U e,2 and U e,3 The desired voltage vector Ue is synthesized; if the desired voltage vector Ue is within the range of [U3, U1], the basic voltage vector U e,3 and U e,1 The synthesis provides the desired voltage vector Ue.

[0080] Step S52 is applicable to the case where the expected voltage vector Ue is in the operable region OZ. e,1～6 The desired voltage vector Ue is provided separately. Here, the power switching elements of the bridge circuit are preferably controlled in such a way that the basic voltage vector Ue, which is located in the operable region AZ and has the smallest angle with the desired voltage vector Ue, is generated. e,1～6 A desired voltage vector Ue is provided separately to provide a wider range of operable region OZ. In the example shown in FIG4 , the desired voltage vector Ue is within the operable region OZ, that is, within the range of (U2-90°, U2)∪(U1, U1+90°). Here, the basic voltage vector Ue for providing the desired voltage vector Ue separately is realized by controlling the normally operating power switching device. e,2 or U e,1 Specifically, if the desired voltage vector Ue is within the range of (U2-90°, U2), the basic voltage vector U e,2 Provide the expected voltage vector Ue separately; if the expected voltage vector Ue is within the range of (U1, U1+90°), the basic voltage vector U e,1 The desired voltage vector Ue is provided separately.

[0081] In step S52, according to this embodiment, referring to the sub-steps of step S52 shown in FIG5 , the controller performs the steps:

[0082] Step S521, determine the basic voltage vector U that provides the desired voltage vector Ue e,1～6 The direction of the desired voltage vector Ue and the basic voltage vector U e,1～6 The angle θ between them;

[0083] Step S522: Calculate the basic voltage vector U according to the following formula: e,1～6 Amplitude:

[0084] U e,1～6 =Ue / cosθ;

[0085] Step S523: The calculated basic voltage vector U e,1～6The amplitude and threshold value U of the basic voltage vector t,1～6 By comparison, if the expected basic voltage vector U e,1～6 The amplitude is greater than the threshold U t,1～6 , then the basic voltage vector U e,1～6 The amplitude is limited to the threshold U t,1～6 .

[0086] The following is a schematic diagram illustrating the steps of providing the desired voltage vector Ue in the operable region when the lower arm of the bridge A is short-circuited, with reference to FIG6 . In the example shown in FIG6 , the desired voltage vector Ue is within the range of (U2-90°, U2), and the direction and magnitude of the desired voltage vector Ue are schematically illustrated by the arrow marked Ue in FIG6 . As described above, in this case, the basic voltage vector Ue is e,2 Here, the controller determines the basic voltage vector U that provides the desired voltage vector Ue in step S521. e,2 The direction of the desired voltage vector Ue and the basic voltage vector U e,2 Then, in step S522, the controller calculates the basic voltage vector U based on the angle θ according to the following formula: e,2 Amplitude: U e,2 =Ue / cosθ. The basic voltage vector U is obtained by calculation e,2 After the amplitude of the basic voltage vector U is e,2 The amplitude and threshold value U of the basic voltage vector t,2 Here, the threshold value U of the basic voltage vector t,1～6 The setting is based on the controller's supply voltage, the controller's maximum output current, the controller and motor's temperature limits, and the motor's field-weakening current limits. For the example in Figure 6, if the basic voltage vector U e,2 The amplitude is greater than the threshold U t,2 , then the basic voltage vector U e,2 The amplitude is limited to the threshold U t,2 , at this time the amplitude is U t,2 The basic voltage vector U e,2 Provide the expected voltage vector separately. If the basic voltage vector U e,2 The amplitude is less than or equal to the threshold U t,2 , then the basic voltage vector U e,2 The amplitude of remains the amplitude calculated by the angle θ.

[0087] Thus, when one bridge arm is short-circuited, for example due to a short-circuit fault of a power switching element, the control device, in particular the controller, uses the remaining five normally operating power switching elements to control the motor to continue to provide the motor torque according to the rotor angle.

[0088] Returning to FIG. 2 , step S53 applies to a case where the desired voltage vector Ue is in the stop zone SZ, such as the case where the desired voltage vector Ue is within the range [U1+90°, U2-90°] as shown in the example of FIG. 4 . In this case, the basic voltage vectors U6, U4, and U5 for providing the desired voltage vector Ue cannot be achieved by controlling the normally operating power switching devices, and the bridge control is stopped.

[0089] After executing step S50, the rotor angular position may change, whether primarily due to the operation of the motor in steps S51 and S52, or due to inertia or other power sources in step S53, such as the vehicle driver manipulating an actuating member used to drive the rotor of the three-phase motor in reverse. Therefore, referring to FIG2 , after executing step S50, step S40 is re-executed to recalculate the desired voltage vector Ue based on the current rotor angular position.

[0090] Those skilled in the art will appreciate that, in principle, there is no restriction on the order in which steps S20 and S30 are executed, especially before the first execution of step S40. Throughout the "limp home" mode, as shown in Figure 2 , the desired voltage vector Ue must be continuously calculated and updated based on the changing rotor position. Therefore, steps S30, S40, and S50 must be executed repeatedly until the control device exits "limp home" mode. Step S20, which determines the voltage space vector-based divisions of the operative area AZ, the operable area OZ, and the stop area SZ based on the shorted bridge arm, does not need to be repeated.

[0091] FIG7 shows a voltage space vector diagram under another motor control method.

[0092] Under the motor drive control method corresponding to FIG7 , when the control device is operating normally, the controller controls two bridges in the three-phase inverter bridge to operate simultaneously. At any given moment, the upper arm of one of the three bridges is connected and the lower arm of another bridge is connected, while the upper and lower arms of the third bridge, excluding the aforementioned two bridges, are both disconnected. This type of motor drive control method is, for example, a six-step commutation method particularly suitable for brushless DC motors. In the voltage-space vector diagram shown in FIG7 , there are six non-zero basic voltage vectors U, W-, V, U-, W, and V-, as well as six sectors I to VI, each of which occupies an angular range of 60°.

[0093] In this control mode where only two bridges in the three-phase inverter bridge work simultaneously, the operating area AZ range is [U base -60°,U base +60°], the range of the operating area OZ is (U base +60°,Ubase +120°)∪(U base -120°,U base -60°), the range of the stop zone SZ is the remaining angle range of the voltage space vector diagram excluding the runnable zone AZ and the operable zone OZ. base It is a basic voltage vector corresponding to the following bridge arm conduction state: in the bridge circuit where the short-circuited bridge arm is located, the short-circuited bridge arm is in the conduction state, and in the other two bridge circuits of the three bridge circuits, the bridge arms opposite to the short-circuited bridge arm are in the conduction state.

[0094] FIG8 shows a case where the operating area, the operable area, and the stop area are determined based on the voltage space vector according to the short-circuited bridge arm under the control method described in FIG7 , that is, the case where the upper bridge arm of bridge B is short-circuited. Here, the corresponding basic voltage vector V(011) is U when the upper bridge arm of bridge B is in the conducting state, the lower bridge arm of bridge A is in the conducting state, and the lower bridge arm of bridge C is in the conducting state. base At this time, the controller can realize the basic voltage vectors W-, V and U- by controlling the other five normally operating power switching devices. In this case, as shown in FIG8 , the operable region AZ is represented by a sector indicated by a grid, and the range of the operable region AZ is [U base -60°,U base +60°], that is, [W-, U-]. As shown in FIG8 , the operable area OZ is represented by a dotted sector. The range of the operable area OZ is (U base +60°,U base +120°)∪(U base -120°,U base -60°), that is, (U-, W) ∪ (U, W-). The range of the stop zone SZ is the remaining angular range of the voltage space vector diagram excluding the operative zone AZ and the operable zone OZ, that is, [W, U].

[0095] Compared with the previous description of the control method involved in Figures 3, 4 and 6, only the division of the operating area, the operable area and the stop area based on the voltage space vector in step S20 is described here. The other steps can refer to the description of Figures 2 to 6.

[0096] Furthermore, in other embodiments, it is reasonable to employ the motor drive control method described in the embodiments of Figures 7 and 8 during normal operation of the control device, in which case only two bridges of the three-phase inverter bridge operate simultaneously. However, if the short-circuit detection unit detects a short circuit in one of the bridge arms, causing the electromechanical device to enter "limp home" mode, the control method described above with respect to Figures 3, 4, and 6 is then switched to, in which case all three bridges of the three-phase inverter bridge operate simultaneously. This maximizes the angular range of the operable zone OZ, enabling relatively stable motor operation.

[0097] In addition, although the controller controls the three bridges in the three-phase inverter bridge to work simultaneously when the control device is operating normally in FIG7 and FIG8

[0098] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

[0099] Reference Signs List

[0100] AZ operational area

[0101] OZ operating area

[0102] SZ Stop Zone

[0103] M motor

Claims

1. A control device for driving a three-phase motor, the control device comprising: A three-phase inverter bridge, comprising three bridge paths (A, B, C), each bridge path comprising a bridge arm between a voltage source node and a phase node and a bridge arm between the phase node and a reference node, the bridge arms respectively comprising power switch elements; A short circuit detection unit configured to perform the steps of: Step S10, detecting whether each bridge arm is short-circuited; A controller configured to perform the following steps: Step S20, if it is detected that one of the bridge arms is short-circuited, determining an operable area (AZ), an operable area (OZ), and a stop area (SZ) divided based on a voltage space vector according to the short-circuited bridge arm; Step S30, calculating the expected voltage vector Ue; Step S40, determining the area where the expected voltage vector Ue is located and determined in step S20; Step S50: controlling the power switch elements of the bridge circuit according to the region where the expected voltage vector Ue is located.

2. The control device according to claim 1, wherein: Controlling the power switch element of the bridge circuit according to the region where the expected voltage vector Ue is located comprises performing the following steps: Step S51, if the desired voltage vector Ue is in the operable area (AZ), controlling the power switch element of the bridge circuit according to the condition that the bridge arm is not short-circuited to provide the desired voltage vector Ue; Step S52: If the desired voltage vector Ue is in the operable region (OZ), the power switch elements of the bridge circuit are controlled so that the basic voltage vector Ue is located in the operable region (AZ) and has the smallest angle with the desired voltage vector Ue. e,1～6 Providing the desired voltage vector Ue separately; Step S53: if the desired voltage vector Ue is in the stop zone (SZ), then stop controlling the bridge circuit.

3. The control device according to claim 2, wherein: In step S52, the controller executes the steps: Step S521, determining the basic voltage vector U that provides the desired voltage vector Ue e,1～6 The direction of the desired voltage vector Ue and the basic voltage vector U e,1～6 The angle θ between them; Step S522, calculate the basic voltage vector U according to the following formula: e,1～6 The amplitude of: And e,1～6 = Ue / cosθ.

4. The control device according to claim 3, wherein: In step S52, the controller further performs the steps: Step S523: The calculated basic voltage vector U e,1～6 The amplitude and threshold value U of the basic voltage vector t,1～6 By comparison, if the basic voltage vector U e,1～6 The magnitude is greater than the threshold U t,1～6 , then the basic voltage vector U e,1～6 The amplitude is limited to the threshold U t,1～6 .

5. The control device according to claim 2, 3 or 4, wherein: The threshold value U of the basic voltage vector t,1～6 The setting is performed according to the power supply voltage of the controller, the maximum output current of the controller, the temperature limit conditions of the controller and the motor, and the weak magnetic current limit conditions of the motor.

6. The control device according to claim 1, wherein: After executing step S50, the controller re-executes step S30 and subsequent steps.

7. The control device according to claim 1, wherein: In the control mode where the three bridges in the three-phase inverter bridge work simultaneously, The range of the operational area (AZ) is [U base -60°,U base +60°], The range of the operable area (OZ) is (U base +60°,U base +150°)∪(U base -150°,U base -60°), The range of the stop zone (SZ) is the voltage space vector diagram minus the operable area (AZ) and the remaining angular range of the operable area (OZ), Among them, U base is the basic voltage vector corresponding to the following bridge arm conduction states: In the bridge circuit where the short-circuited bridge arm is located, the short-circuited bridge arm is in a conducting state, and In the other two bridge circuits among the three bridge circuits, the bridge arms opposite to the short-circuited bridge arm are in a conducting state.

8. The control device according to claim 1, wherein: In the control mode where only two bridges in the three-phase inverter bridge work simultaneously, The range of the operational area (AZ) is [U base -60°,U base +60°], The range of the operable area (OZ) is (U base +60°,U base +120°)∪(U base -120°,U base -60°), The range of the stop zone (SZ) is the remaining angle range of the voltage space vector diagram excluding the operable zone (AZ) and the operable zone (OZ). Among them, U base is the basic voltage vector corresponding to the following bridge arm conduction states: In the bridge circuit where the short-circuited bridge arm is located, the short-circuited bridge arm is in a conducting state, and In the other two bridge circuits among the three bridge circuits, the bridge arms opposite to the short-circuited bridge arm are in a conducting state.

9. An electromechanical system comprising: Three-phase motor; as well as The control device according to claims 1 to 8, configured to drive the three-phase motor.

10. The electromechanical system of claim 9, wherein: The electromechanical system is an electronic power-assist system for a vehicle or a driving system for driving a vehicle, and in particular includes an actuating component for driving the rotor of the three-phase motor to rotate by means of an external force.

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