Control method and control device of permanent magnet synchronous motor and permanent magnet synchronous motor system

Abstract

The application provides a control method and device of a permanent magnet synchronous motor and a permanent magnet synchronous motor system. The permanent magnet synchronous motor is electrically connected with an inverter, the inverter is used for driving the permanent magnet synchronous motor, and the inverter comprises three phases, each phase comprising an upper bridge and a lower bridge. The method comprises the following steps: obtaining a time sequence control signal of a target phase in a target moment in a current period; in the case that the time sequence control signal represents that the target phase is controlled to be turned on, controlling the upper bridge of the target phase to be turned on according to a first duty ratio and controlling the lower bridge of the target phase to be turned on according to a second duty ratio; collecting a current of the target phase to obtain a target phase current; in the case that the target phase current is less than a preset current, controlling the permanent magnet synchronous motor to be in a short-circuit braking state; and in the case that the target phase current is greater than or equal to the preset current, controlling the upper bridge and the lower bridge of the three phases to be turned off so that the permanent magnet synchronous motor is turned off. Through the application, the problem that a single resistor cannot obtain a current in the case that the permanent magnet synchronous motor is in a short-circuit braking state is solved.

Description

Technical Field

[0001] This application relates to the field of motor control, and more specifically, to a control method, control device, permanent magnet synchronous motor system, computer-readable storage medium, and electronic device for a permanent magnet synchronous motor. Background Technology

[0002] Currently, variable frequency air conditioner compressors generally use permanent magnet synchronous motors as power sources. To improve the cooling and heating capacity of the air conditioner, the permanent magnet synchronous motor needs to operate at high speed. If the unit stops at this time, the back electromotive force (EMF) of the permanent magnet motor may be higher than the DC bus voltage. This back EMF will charge the bus capacitor, creating a pump-up voltage. Excessive pump-up voltage can cause overvoltage damage to components or trigger overvoltage protection. Therefore, to reduce the pump-up voltage, the traditional method is to short-circuit the inverter's lower bridge, allowing the motor's kinetic energy to be dissipated through its internal impedance. The motor current does not pass through the bus, thus preventing charging of the bus capacitor. During the short-circuit lower bridge process, the phase current of the permanent magnet motor needs to be monitored in real time. If the phase current is too high, the switch needs to be turned off to prevent demagnetization of the permanent magnet motor due to excessive current. However, in the current variable frequency air conditioner industry, compressor current sampling generally uses a single resistor. But when the lower bridge is short-circuited, the motor current does not flow through the sampling resistor, the controller cannot collect the phase current, and therefore cannot effectively protect the motor.

[0003] Therefore, how to use a single resistor to collect the phase current of the air conditioner compressor under the above conditions is a technical problem that needs to be solved. Summary of the Invention

[0004] The main objective of this application is to provide a control method, control device, computer-readable storage medium, and electronic device for a permanent magnet synchronous motor, so as to at least solve the problem that the phase current cannot be collected when the permanent magnet synchronous motor is short-circuited for braking in the prior art.

[0005] To achieve the above objectives, according to one aspect of this application, a control method for a permanent magnet synchronous motor is provided. The permanent magnet synchronous motor is electrically connected to an inverter, the inverter being used to drive the permanent magnet synchronous motor, and the inverter comprising three phases, each phase comprising an upper bridge and a lower bridge. The method includes: acquiring a timing control signal for a target time of a target phase within the current cycle, wherein the timing control signal is a signal used to control whether the target phase is turned on; when the timing control signal indicates that the target phase is turned on, controlling the upper bridge of the target phase to turn on according to a first duty cycle and controlling the lower bridge of the target phase to turn on according to a second duty cycle, wherein the first duty cycle is much smaller than the second duty cycle; acquiring the current of the target phase to obtain the target phase current; when the target phase current is less than a preset current, controlling the permanent magnet synchronous motor to be in a short-circuit braking state; when the target phase current is greater than or equal to the preset current, controlling the upper bridge and the lower bridge of the three phases to turn off, thereby turning off the permanent magnet synchronous motor.

[0006] Optionally, controlling the upper bridge of the target phase to conduct according to a first duty cycle includes: acquiring the current of the target phase in the previous cycle to obtain the current of the previous target phase, wherein the previous cycle is a cycle adjacent to the current cycle and preceding the current cycle; and controlling the upper bridge of the target phase to conduct according to the first duty cycle when the current of the previous target phase is less than 0.

[0007] Optionally, the method further includes: when the current of the previous target phase is greater than 0, obtaining the dead time, adding the first duty cycle to the dead time by a predetermined multiple to obtain a third duty cycle; and controlling the upper bridge of the target phase to conduct according to the third duty cycle.

[0008] Optionally, the timing control signal controls each phase to conduct in a predetermined order within each cycle. After acquiring the current of the target phase and obtaining the target phase current, the method further includes: acquiring the current of the phase preceding the target phase to obtain the first phase current; calculating the sum of the first phase current and the target phase current to obtain the sum of phase currents; determining the negative sum of the phase currents as the current of the next phase of the target phase to obtain the second phase current; controlling the permanent magnet synchronous motor to be in the short-circuit braking state when the first phase current or the second phase current is less than the preset current; and controlling the upper bridge and the lower bridge of the three phases to turn off when the first phase current or the second phase current is greater than or equal to the preset current, so as to turn off the permanent magnet synchronous motor.

[0009] Optionally, obtaining the timing control signal of the target moment of the target phase within the current period includes: obtaining a one-to-one mapping relationship between time and pulse signals within the current period, wherein the pulse signal includes a high-level signal and a low-level signal, the high-level signal indicating conduction and the low-level signal indicating deactivation; determining the midpoint of the time period corresponding to the high-level signal as the target moment, and obtaining the timing control signal of the target moment.

[0010] Optionally, after controlling the upper bridge of the target phase to conduct according to a first duty cycle and controlling the lower bridge of the target phase to conduct according to a second duty cycle, the method further includes: controlling the upper bridge of two phases other than the target phase in the three phases of the permanent magnet synchronous motor to turn off, and controlling the lower bridge of the two phases other than the target phase in the three phases to conduct.

[0011] According to another aspect of this application, a control device for a permanent magnet synchronous motor is provided. The permanent magnet synchronous motor is electrically connected to an inverter, the inverter being used to drive the permanent magnet synchronous motor, and the inverter comprising three phases, each phase comprising an upper bridge and a lower bridge, comprising: an acquisition unit, configured to acquire a timing control signal at a target time within the current cycle, wherein the timing control signal is a signal characterizing the conduction of each phase of the permanent magnet synchronous motor; a first control unit, configured to, when the timing control signal characterizes the conduction of the target phase, control the upper bridge of the target phase to conduct according to a first duty cycle, and control the lower bridge of the target phase to conduct according to a second duty cycle, wherein the first duty cycle is much smaller than the second duty cycle; and a second control unit, configured to acquire the current of the target phase, obtain the target phase current, control the permanent magnet synchronous motor to be in a short-circuit braking state when the target phase current is less than a preset current, and control the upper bridge and the lower bridge of the three phases to be turned off when the target phase current is greater than or equal to the preset current, so as to shut down the permanent magnet synchronous motor.

[0012] According to another aspect of this application, a permanent magnet synchronous motor system is provided, including a permanent magnet synchronous motor, a bus capacitor, a sampling resistor, a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch. The permanent magnet synchronous motor includes three phases. Each switch is connected in parallel with a diode. The first switch and the second switch are connected in series through a first node to form a first branch. The third switch and the fourth switch are connected in series through a second node to form a second branch. The fifth switch and the sixth switch are connected in series through a third node to form a third branch. The first terminal of the bus capacitor is connected to the first terminal of the first branch. The first end of the second branch and the first end of the third branch are electrically connected. The second ends of the first branch, the second ends of the second branch, and the second ends of the third branch are electrically connected. The second end of the bus capacitor is electrically connected to the first end of the sampling resistor. The second end of the sampling resistor is electrically connected to the second end of the second branch. The first phase of the permanent magnet synchronous motor is electrically connected to the first node. The second phase of the permanent magnet synchronous motor is electrically connected to the second node. The third phase of the permanent magnet synchronous motor is electrically connected to the third node. The permanent magnet synchronous motor includes a program for executing any of the control methods described above.

[0013] According to another aspect of this application, a computer-readable storage medium is provided, the computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to perform any of the control methods described above.

[0014] According to another aspect of this application, an electronic device is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including methods for performing any of the control methods described herein.

[0015] By applying the technical solution of this application, the upper and lower bridges of the target phase are controlled to conduct according to the first and second duty cycles, respectively, through timing control signals. After conduction, the target phase current is collected. When the target phase current is less than the preset current, the permanent magnet synchronous motor is controlled to be in a short-circuit braking state. When the target phase current is greater than or equal to the preset current, the three-phase upper and lower bridges are turned off, causing the current of the permanent magnet synchronous motor to decrease and preventing excessive current from causing demagnetization of the air conditioner compressor motor. Compared with the prior art, where a single resistor cannot collect the target phase current when the permanent magnet synchronous motor is running at high speed, thus making it impossible to monitor whether the target phase current is too large, this application can control the target phase to conduct according to the timing control signal and collect the target phase current. Therefore, it can solve the problem in the prior art that a single resistor cannot collect the target phase current when the motor is short-circuited, achieving the effect of timely collection of the target phase current and monitoring the motor's operating status. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1 A flowchart illustrating a control method for a permanent magnet synchronous motor provided in an embodiment of this application is shown.

[0018] Figure 2 A schematic diagram of the structure of a permanent magnet synchronous motor system provided in an embodiment of this application is shown;

[0019] Figure 3 A flowchart illustrating a specific control method for a permanent magnet synchronous motor provided in this application is shown.

[0020] Figure 4 The waveforms of three-phase current and bus current of a permanent magnet synchronous motor provided in this application are shown.

[0021] Figure 5 The diagram shows the phase current and bus voltage waveforms of a permanent magnet synchronous motor provided in this application when it stops at high speed without any corresponding stop control method.

[0022] Figure 6 The diagram shows the phase current and bus voltage waveforms of a permanent magnet synchronous motor under dead-zone-free compensation conditions provided in this application.

[0023] Figure 7 The phase current and bus voltage waveforms of a control method for a permanent magnet synchronous motor under dead-zone compensation provided in this application are shown.

[0024] Figure 8A structural block diagram of a control device for a permanent magnet synchronous motor provided in an embodiment of this application is shown. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] As described in the background section, in the prior art, when a permanent magnet synchronous motor stops at high speed, the lower bridge of the inverter is usually short-circuited to reduce the pump boost voltage. This causes the motor current to not flow through the sampling resistor, and the phase current is generally collected through a single sampling resistor. Therefore, the phase current cannot be collected under the above circumstances, thus failing to effectively protect the motor. To solve the problem that a single resistor cannot collect the phase current, the embodiments of this application provide a control method, control device, permanent magnet synchronous motor system, computer-readable storage medium, and electronic device for a permanent magnet synchronous motor.

[0029] For ease of description, the nouns or terms used in the embodiments of this application are explained below:

[0030] Pump-up voltage: Variable frequency air conditioner compressors generally use permanent magnet synchronous motors as power sources. To improve the cooling and heating capacity of the air conditioner, the permanent magnet synchronous motor needs to operate at high speed. If the unit needs to be stopped at this time, and the back EMF of the permanent magnet motor is higher than the DC bus voltage, the back EMF will charge the bus capacitor, forming a pump-up voltage. Excessive pump-up voltage can cause overvoltage damage to components or trigger overvoltage protection.

[0031] Fault-free shutdown: refers to shutdown without any motor malfunction.

[0032] Fault shutdown: refers to the shutdown of the motor due to faults such as overcurrent or loss of synchronism.

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0034] This embodiment provides a control method for a permanent magnet synchronous motor that runs on a mobile terminal, computer terminal, or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0035] Figure 1 This is a flowchart of a control method for a permanent magnet synchronous motor according to an embodiment of this application. The permanent magnet synchronous motor is electrically connected to an inverter, which drives the permanent magnet synchronous motor. The inverter includes three phases, each phase including an upper bridge and a lower bridge, as shown below. Figure 1 As shown, the method includes the following steps:

[0036] Step S201: Obtain the timing control signal of the target time of the target phase within the current period, wherein the timing control signal is a signal used to control whether the target phase is turned on.

[0037] Specifically, variable frequency air conditioner compressors generally use permanent magnet synchronous motors as power sources. To ensure the cooling or heating effect of variable frequency air conditioners, permanent magnet synchronous motors typically operate at high speeds. Stopping at high speeds can easily lead to voltage surge. To reduce this voltage surge, the lower bridge of the inverter in the permanent magnet synchronous motor system is usually short-circuited. However, with the lower bridge short-circuited, a single resistor cannot collect the phase current, thus making it impossible to monitor the motor's phase current. Excessive phase current may damage the motor. Therefore, this application, based on short-circuiting the lower bridge of the inverter, uses a timing control signal to drive the upper bridge to conduct. Specifically, it first acquires the timing control signal for the target phase at the target time within the current control cycle. The target phase can be any one of the three phases, the current cycle is the control cycle corresponding to the target, and the target time can be the midpoint of the time period corresponding to the conduction.

[0038] Step S202: When the timing control signal indicates that the target phase is turned on, the upper bridge of the target phase is turned on according to the first duty cycle, and the lower bridge of the target phase is turned on according to the second duty cycle, wherein the first duty cycle is much smaller than the second duty cycle.

[0039] Specifically, the current is typically measured through a single sampling resistor to check the bus current. By activating the upper bridge, the upper and lower bridges complement each other, allowing the motor current to flow through the sampling resistor. The upper bridge's conduction time serves as the current sampling window, ensuring the controller can acquire the current. Therefore, the upper bridge's duty cycle is close to 0, and the lower bridge's duty cycle is close to 100%. When the timing control signal is high, it can be recorded as: state1 = 1, generally indicating that the target phase is conducting. The first duty cycle can be 2%, and the second duty cycle can be 98%, meaning the upper bridge conducts with a 2% duty cycle, and the lower bridge conducts with a 98% duty cycle.

[0040] Step S203: Collect the current of the target phase to obtain the target phase current. If the target phase current is less than the preset current, control the permanent magnet synchronous motor to be in a short-circuit braking state. If the target phase current is greater than or equal to the preset current, control the upper bridge and lower bridge of the three phases to shut down the permanent magnet synchronous motor.

[0041] Specifically, if the target phase current amplitude is greater than or equal to the preset current I limit When the current is at the set point, the switch is turned off; otherwise, the switch is enabled. This limits the peak current of the permanent magnet synchronous motor to near the preset current. To better limit the actual current to near the set value, the control cycle Ts should be minimized. This limits the motor current and prevents damage caused by excessive current. It should be noted that a single resistor cannot obtain the phase current, while two resistors can. However, using two resistors is more expensive than using a single resistor, so single resistors are currently more commonly used. This application mainly provides a scheme for short-circuit braking with a single resistor; such a complex scheme is not necessary for two resistors.

[0042] In this embodiment, the upper and lower bridges of the target phase are controlled to conduct according to a first duty cycle and a second duty cycle, respectively, via timing control signals. After conduction, the target phase current is collected. If the target phase current is less than a preset current, the permanent magnet synchronous motor is controlled to be in a short-circuit braking state. If the target phase current is greater than or equal to the preset current, the three-phase upper and lower bridges are turned off, causing the current of the permanent magnet synchronous motor to decrease and preventing excessive current from causing demagnetization of the air conditioner compressor motor. Compared with the prior art, where a single resistor cannot collect the target phase current when the permanent magnet synchronous motor is running at high speed, thus making it impossible to monitor whether the target phase current is too large, this application can control the target phase to conduct according to the timing control signals and collect the target phase current. Therefore, it can solve the problem in the prior art that a single resistor cannot collect the target phase current when the motor is short-circuited, achieving the effect of timely collection of the target phase current and monitoring the motor's operating status.

[0043] It should be noted that this application applies to both fault-free shutdown and fault-based shutdown (such as overcurrent, loss of synchronism, etc.) of permanent magnet motors.

[0044] In specific implementation, step S202, which controls the upper bridge of the target phase to conduct according to the first duty cycle, can be achieved through the following steps: obtaining the current of the target phase in the previous cycle, wherein the previous cycle is the cycle adjacent to and preceding the current cycle; when the current of the previous target phase is less than 0, controlling the upper bridge of the target phase to conduct according to the first duty cycle. This method controls the target phase to conduct according to the first duty cycle under the above conditions, thus accurately measuring the target current value.

[0045] Specifically, in the actual implementation process, due to the influence of the inverter dead time, the charging pulse width of the bus capacitor is greater than the discharging pulse width, and the difference is twice the dead time. This will eventually cause the bus voltage to rise during the shutdown control phase. Therefore, the current of the target phase in the previous cycle, i.e. the current of the previous target phase, is obtained first. The current of the previous target phase is less than 0, indicating that no dead time compensation is needed. Therefore, the circuit is still turned on according to the first duty cycle.

[0046] To avoid the influence of inverter dead time, the above method further includes the following steps: when the current of the target phase is greater than 0, the dead time is obtained, and the first duty cycle is added to the dead time by a predetermined multiple to obtain a third duty cycle; the upper bridge of the target phase is controlled to conduct according to the third duty cycle. This method performs dead time compensation under the above conditions, which can compensate for the problem of inconsistent charging and discharging times of the bus capacitor caused by dead time.

[0047] In practice, as mentioned above, the inverter's dead time causes a mismatch between the charging and discharging times of the bus capacitors, with the charging time exceeding the discharging time. This leads to an increase in bus voltage, even with increased pump-up voltage. Therefore, when the target phase current is greater than 0, dead time compensation is necessary. Due to the inverter's dead time, the charging pulse width of the bus capacitors is greater than the discharging pulse width, with a difference of twice the dead time. Therefore, twice the dead time is added to the original first duty cycle to obtain a new third duty cycle. The upper bridge conduction time is then the third duty cycle. This ensures that the charging and discharging times of the bus capacitors are the same, preventing a rise in bus voltage and avoiding damage to the motor.

[0048] In some optional embodiments, the timing control signal controls the conduction of each phase in a predetermined order within each cycle. After acquiring the current of the target phase in step S203, the method further includes the following steps: acquiring the current of the phase preceding the target phase to obtain the first phase current; calculating the sum of the first phase current and the target phase current to obtain the sum of phase currents; determining the negative sum of the phase currents as the current of the next phase of the target phase to obtain the second phase current; controlling the permanent magnet synchronous motor to be in a short-circuit braking state when the first phase current or the second phase current is less than the preset current; controlling the upper and lower bridges of the three phases to turn off when the first phase current or the second phase current is greater than or equal to the preset current, thereby shutting off the permanent magnet synchronous motor. This method calculates the current of each phase through the above steps, thus monitoring the current of each phase and promptly shutting off the motor when the current exceeds the preset current.

[0049] Specifically, the three phases of the motor are represented by phases A, B, and C. The sum of the currents in the three phases is 0, and the predetermined order is phase A, phase B, and phase C. Assuming the current cycle switching state is 1 (state = 1), then the duty cycle of the upper bridge of phase A (the target phase) is 2%, and the duty cycle of the lower bridge is 98%. During this switching cycle, when the upper bridge of phase A is turned on, the phase A current flows through the sampling resistor. The controller collects the phase A current and uses the sampled value from the previous state: the phase C current (the first phase current), and calculates the phase B current (the second phase current) using the fact that the sum of the three phase currents is 0. In the next cycle, the switching state is 2 (state = 2), and phase B is the target phase. Then, the duty cycle of the upper bridge of phase B is 2%, and the duty cycle of the lower bridge is 98%. During this switching cycle, when the upper bridge of phase B is turned on, the phase B current flows through the sampling resistor. The controller collects the phase B current and uses the sampled value from the previous state: the phase A current (the first phase current), and calculates the phase C current (the second phase current) using the fact that the sum of the three phase currents is 0. In the next cycle, the switching state is 3 (state = 3). Phase C is the target phase, with an upper bridge duty cycle of 2% and a lower bridge duty cycle of 98%. During this switching cycle, when the upper bridge of phase C is on, the phase C current flows through the sampling resistor. The controller collects the phase C current and uses the sampled value from the previous state: the phase B current (first phase current). It then calculates the phase A current (second phase current) using the fact that the sum of the three phase currents is 0. This cycle continues until the shutdown control ends. From the above analysis, it can be concluded that the controller can detect the three-phase current amplitude after only 3 switching cycles. If the amplitude of any phase current is greater than the preset current I... limit When the current is at the set point, turn off the switch; otherwise, enable the switch to limit the peak current of the motor to near the preset current. In order to better limit the actual current to near the preset current, the control cycle Ts should be minimized as much as possible.

[0050] In order to accurately obtain the timing control signal at the target moment of the target phase in the current cycle, the above step S201 may be implemented through the following steps: acquiring a one-to-one mapping relationship between time and pulse signals in the current cycle, wherein the pulse signals include a high-level signal and a low-level signal, the high-level signal represents turn-on, and the low-level signal represents turn-off; determining the midpoint time of the time period corresponding to the high-level signal as the target moment, and acquiring the timing control signal at the target moment. This method determines the above midpoint time as the target moment, so that the timing control signal corresponding to the target moment can be accurately acquired.

[0051] Specifically, the bus current when the upper bridge is turned on is analyzed by taking phase A as an example. The current flowing into the motor is defined as positive, and the current flowing out of the motor is defined as negative. When the phase A current is positive and the upper bridge is turned on, the bus current flows into the motor, and the bus capacitor discharges at this time. When the phase A current is negative and the upper bridge is turned on, the phase A current charges the bus capacitor through the anti-parallel diode of the switching tube 1. The amplitude of the charging and discharging current is the amplitude of the phase A current |Ia|. Let the midpoint time of the upper bridge turn-on pulse width in switching state 1 be t1, which is the target moment, the midpoint time of the upper bridge turn-on pulse width in switching state 2 be t2, the midpoint time of the upper bridge turn-on pulse width in switching state 3 be t3, and t1<t2<t3, the shutdown control calling time interval T s =t2-t1=t3-t2, if T s is sufficiently small, for the three-phase currents of the motor: Ia(t1)+Ib(t2)+Ic(t3)=0, that is, the charging current and the discharging current of the bus capacitor are balanced, the charging energy and the discharging energy are equivalent, and the bus voltage will not change.

[0052] In some optional implementations, after the above step S202 of controlling the upper bridge of the target phase to be turned on according to a first duty ratio and controlling the lower bridge of the target phase to be turned on according to a second duty ratio, the method further includes the following steps: turning off the upper bridges of the two phases other than the target phase among the three phases of the permanent magnet synchronous motor, and controlling the lower bridges of the two phases other than the target phase among the three phases to be turned on. This method controls the upper bridges of the remaining two phases to be turned off and the lower bridges thereof to be turned on, so that the pump-up voltage can be reduced.

[0053] In the specific implementation, to prevent excessively high pump voltage, assuming the current cycle switch state is 1 (state=1), then the duty cycle of the upper bridge of phase A is 2%, and the duty cycle of the lower bridge is 98%, while the duty cycles of the upper bridge of phases B and C are 0%, and the duty cycle of the lower bridge is 100%. In the next cycle, the switch state is 2 (state=2), then the duty cycle of the upper bridge of phase B is 2%, and the duty cycle of the lower bridge is 98%, while the duty cycles of the upper bridge of phases A and C are 0%, and the duty cycle of the lower bridge is 100%. In the following cycle, the switch state is 3 (state=3), then the duty cycle of the upper bridge of phase C is 2%, and the duty cycle of the lower bridge is 98%, while the duty cycles of the upper bridge of phases A and B are 0%, and the duty cycle of the lower bridge is 100%. That is, the upper bridge is off, and the lower bridge is on.

[0054] This application also provides expressions for the dq-axis current under short-circuit steady-state conditions applicable to surface-mounted and embedded permanent magnet synchronous motors:

[0055]

[0056] Where w is the electric angular frequency of the motor. Let w be the motor flux linkage, Lq be the quadrature-axis inductance, Ld be the direct-axis inductance, and R be the phase resistance. When w × Ld >> R, the amplitude of the dq-axis current is approximately:

[0057]

[0058] The phase current amplitude Is is:

[0059]

[0060] Therefore, the phase current amplitude under steady state is independent of the motor speed.

[0061] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the control method for the permanent magnet synchronous motor of this application will be described in detail below with reference to specific embodiments.

[0062] This embodiment relates to a specific control method for a permanent magnet synchronous motor. Figure 2This application provides a schematic diagram of a permanent magnet synchronous motor system, including a permanent magnet synchronous motor, a bus capacitor, a sampling resistor Rs, switches 1, 2, 3, 4, 5, and 6. The permanent magnet synchronous motor has three phases, ea, eb, and ec. Each switch is connected in parallel with a diode. Switch 1 and switch 2 are connected in series through a first node to form a first branch, i.e., phase A. Switch 3 and switch 4 are connected in series through a second node to form a second branch, i.e., phase B. Switch 5 and switch 6 are connected in series through a third node to form a third branch, i.e., phase C. The first end of the bus capacitor is electrically connected to the first end of the first branch, the first end of the second branch, and the first end of the third branch. The second ends of phases A, B, and C are electrically connected. The second end of the bus capacitor is electrically connected to the first end of the sampling resistor. The second end of the sampling resistor is electrically connected to the second end of the second branch. The first phase of the permanent magnet synchronous motor is electrically connected to phase A. The second phase of the permanent magnet synchronous motor is electrically connected to phase B. The third phase of the permanent magnet synchronous motor is electrically connected to phase C. Figure 3 A flowchart illustrating a specific control method for a permanent magnet synchronous motor provided in this application is shown, including the following steps:

[0063] Step S1: Shutdown control entry;

[0064] Step S2: state++, if state>3, state=1. This judgment condition is the program code judgment condition, that is, to obtain the timing control signal, add 1 to the signal to obtain the timing control signal of the current cycle. If it is greater than 3, then assign the value 1 and continue to control from the first phase (there are three phases in total).

[0065] Step S3: state = 1? In the case of Y (yes), the duty cycle of the upper bridge of phase A (target phase) is 2% (first duty cycle) and the duty cycle of the lower bridge is 98% (second duty cycle). The duty cycles of the upper bridges of phases B and C are 0% (off) and 100% (on). During this switching cycle, when the upper bridge of phase A is on, the phase A current flows through the sampling resistor. The controller collects the phase A current (target phase current) and uses the sampling value of the previous state: the phase C current (first phase current). It calculates the phase B current (second phase current) by using the fact that the sum of the three phase currents is 0.

[0066] Step S4: Perform dead time compensation. If the previous A-phase sampling current was positive, then add twice the dead time to the upper bridge conduction time, so that the upper and lower bridges are complementary; otherwise, do not add.

[0067] Step S5: In the case of N (No), determine if state = 2? In the case of Y (Yes), the duty cycle of the upper bridge of phase B (target phase) is 2% (first duty cycle), and the duty cycle of the lower bridge is 98% (second duty cycle). The duty cycles of the upper bridges of phases A and C are 0% (off) and 100% (on). During this switching cycle, when the upper bridge of phase B is on, the phase B current flows through the sampling resistor. The controller collects the phase B current (target phase current) and uses the sampling value of the previous state: the phase A current (first phase current). It calculates the phase C current (second phase current) by using the fact that the sum of the three phase currents is 0.

[0068] Step S6: Perform dead time compensation. If the previous B-phase sampling current is positive, then add twice the dead time to the upper bridge conduction time, so that the upper and lower bridges complement each other; otherwise, do not add.

[0069] Step S7: In the case of N (No), state = 3, the duty cycle of the upper bridge of phase C (target phase) is 2% (first duty cycle), the duty cycle of the lower bridge is 98% (second duty cycle), the duty cycle of the upper bridge of phase A and phase B is 0% (off), and the duty cycle of the lower bridge is 100% (on). During this switching cycle, when the upper bridge of phase C is on, the current of phase C flows through the sampling resistor. The controller collects the current of phase C (target phase current) and uses the sampling value of the previous state: the current of phase B (first phase current), and calculates the current of phase A (second phase current) by using the fact that the sum of the three phase currents is 0.

[0070] Step S8: Perform dead time compensation. If the previous C-phase sampling current is positive, then add twice the dead time to the upper bridge conduction time, so that the upper and lower bridges complement each other; otherwise, do not add.

[0071] Step S9: If the amplitude of any phase current is greater than the set value I limit When the preset current is reached, the switch is turned off; otherwise, the switch is enabled.

[0072] Step S10: Stop control ends? If Y (yes), stop control ends; if N (no), proceed to step S2.

[0073] Figure 4 The waveforms of the three-phase current and bus current of the permanent magnet synchronous motor are shown below. The upper part represents the motor's A-phase current Ia, B-phase current Ib, and C-phase current Ic, respectively, while the lower part represents the bus current. When the timing control signal state=1, Ia conducts; when state=2, Ib conducts; and when state=3, Ic conducts. When there is current in the bus, it flows through the sampling resistor, allowing the controller to collect the current. Under the same test conditions, Figure 5 The waveforms of phase current and bus voltage of a permanent magnet synchronous motor when it stops at high speed without any corresponding stop control method are shown. The upper waveform is the bus voltage waveform, and the lower waveform is the phase current waveform. When the motor stops, the bus voltage is pumped up (pumped voltage) to 65V. Figure 6 The waveforms of phase current and bus voltage under the control method of this application without dead zone compensation are shown. However, without dead zone compensation, the upper waveform is the bus voltage waveform and the lower waveform is the phase current waveform. When the motor runs to the stop, the stop control is adopted and the bus voltage is pumped up (pumped up voltage) to 30V. Figure 7 The waveforms of phase current and bus voltage under dead-zone compensation conditions are shown in the control method of this application. The upper waveform is the bus voltage waveform, and the lower waveform is the phase current waveform. When the motor stops, shutdown control and dead-zone compensation are applied, and the bus voltage rise (rise voltage) is 0V. That is, after the above-mentioned control method and dead-zone compensation in this application, the rise voltage is 0V. Compared with no dead-zone compensation and existing methods, the rise voltage is the lowest and the effect is the best, avoiding damage to the motor caused by excessive rise voltage.

[0074] This application also provides a control device for a permanent magnet synchronous motor. It should be noted that the control device for the permanent magnet synchronous motor in this application can be used to execute the control method for the permanent magnet synchronous motor provided in this application. This device is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0075] The control device for the permanent magnet synchronous motor provided in the embodiments of this application is described below.

[0076] Figure 8 This is a schematic diagram of a control device for a permanent magnet synchronous motor according to an embodiment of this application. The permanent magnet synchronous motor is electrically connected to an inverter, which drives the permanent magnet synchronous motor. The inverter includes three phases, each phase including an upper bridge and a lower bridge, as shown below. Figure 8 As shown, the device includes:

[0077] The acquisition unit 10 is used to acquire the timing control signal of the target time within the current cycle, wherein the timing control signal is a signal characterizing the conduction of each phase of the permanent magnet synchronous motor.

[0078] Specifically, variable frequency air conditioner compressors generally use permanent magnet synchronous motors as power sources. To ensure the cooling or heating effect of variable frequency air conditioners, permanent magnet synchronous motors typically operate at high speeds. Stopping at high speeds can easily lead to voltage surge. To reduce this voltage surge, the lower bridge of the inverter in the permanent magnet synchronous motor system is usually short-circuited. However, with the lower bridge short-circuited, phase current cannot be collected, thus making it impossible to monitor the motor's phase current. Excessive phase current may damage the motor. Therefore, this application, based on short-circuiting the lower bridge of the inverter, uses a timing control signal to drive the upper bridge to conduct. Specifically, it first acquires the timing control signal for the target phase at the target time within the current control cycle. The target phase can be any one of the three phases, the current cycle is the control cycle corresponding to the target, and the target time can be the midpoint of the time period corresponding to the conduction.

[0079] The first control unit 20 is configured to control the upper bridge of the target phase to conduct according to a first duty cycle and control the lower bridge of the target phase to conduct according to a second duty cycle when the timing control signal indicates that the target phase is conducting, wherein the first duty cycle is much smaller than the second duty cycle.

[0080] Specifically, the current is typically measured using a single sampling resistor connected in series with the bus capacitor. By activating the upper bridge, which is complementary to the lower bridge, the motor current flows through the sampling resistor. The upper bridge's conduction time serves as the current sampling window, ensuring the controller can acquire the current. Therefore, the upper bridge's duty cycle is close to 0, and the lower bridge's duty cycle is close to 100%. When the timing control signal is high, it can be represented as state1 = 1, generally indicating that the target phase is conducting. The first duty cycle can be 2%, and the second duty cycle can be 98%, meaning the upper bridge conducts with a 2% duty cycle, and the lower bridge conducts with a 98% duty cycle.

[0081] The second control unit 30 is used to collect the current of the target phase and obtain the target phase current. When the target phase current is less than the preset current, the control unit controls the permanent magnet synchronous motor to be in a short-circuit braking state. When the target phase current is greater than or equal to the preset current, the control unit controls the upper bridge and lower bridge of the three phases to shut down the permanent magnet synchronous motor.

[0082] Specifically, if the target phase current amplitude is greater than or equal to the preset current I limit When the current is high, the switch is turned off; otherwise, the switch is enabled. This limits the peak current of the permanent magnet synchronous motor to near the preset current. To better limit the actual current to near the set value, the control cycle Ts should be minimized. This limits the motor current and prevents damage to the motor from excessive current.

[0083] In this embodiment, the upper and lower bridges of the target phase are controlled to conduct according to a first duty cycle and a second duty cycle, respectively, via timing control signals. After conduction, the target phase current is collected. If the target phase current is less than a preset current, the permanent magnet synchronous motor is controlled to be in a short-circuit braking state. If the target phase current is greater than or equal to the preset current, the three-phase upper and lower bridges are turned off, causing the current of the permanent magnet synchronous motor to decrease and preventing excessive current from causing demagnetization of the air conditioner compressor motor. Compared with the prior art, where a single resistor cannot collect the target phase current when the permanent magnet synchronous motor is running at high speed, thus failing to monitor whether the target phase current is too large, this application can control the target phase to conduct according to the timing control signals and collect the target phase current. Therefore, it can solve the problem in the prior art where a single resistor cannot collect the target phase current when the motor is short-circuited, achieving the effect of timely collection of the target phase current and monitoring the motor's operating status.

[0084] It should be noted that this application applies to both fault-free shutdown and fault-based shutdown (such as overcurrent, loss of synchronism, etc.) of permanent magnet motors.

[0085] In its specific implementation, the first control unit includes an acquisition module and a control module. The acquisition module acquires the current of the target phase in the previous cycle to obtain the previous target phase current. The previous cycle is the cycle adjacent to and preceding the current cycle. The control module controls the upper bridge of the target phase to conduct according to the first duty cycle when the previous target phase current is less than 0. Under these conditions, the device controls the target phase to conduct according to the first duty cycle, thus accurately measuring the target current value.

[0086] Specifically, in the actual implementation process, due to the influence of the inverter dead time, the charging pulse width of the bus capacitor is greater than the discharging pulse width, and the difference is twice the dead time. This will eventually cause the bus voltage to rise during the shutdown control phase. Therefore, the current of the target phase in the previous cycle, i.e. the current of the previous target phase, is obtained first. The current of the previous target phase is less than 0, indicating that no dead time compensation is needed. Therefore, the circuit is still turned on according to the first duty cycle.

[0087] To avoid the influence of inverter dead time, the aforementioned device further includes an addition unit and a third control unit. The addition unit is used to obtain the dead time when the current of the previous target phase is greater than 0, and adds the first duty cycle to the dead time by a predetermined multiple to obtain a third duty cycle. The third control unit is used to control the upper bridge of the target phase to conduct according to the third duty cycle. This device performs dead time compensation under the above conditions, thus compensating for the inconsistency between the charging and discharging times of the bus capacitor caused by the dead time.

[0088] In practice, as mentioned above, the inverter's dead time causes a mismatch between the charging and discharging times of the bus capacitors, with the charging time exceeding the discharging time. This leads to an increase in bus voltage, even with increased pump-up voltage. Therefore, when the target phase current is greater than 0, dead time compensation is necessary. Due to the inverter's dead time, the charging pulse width of the bus capacitors is greater than the discharging pulse width, with a difference of twice the dead time. Therefore, twice the dead time is added to the original first duty cycle to obtain a new third duty cycle. The upper bridge conduction time is then the third duty cycle. This ensures that the charging and discharging times of the bus capacitors are the same, preventing a rise in bus voltage and avoiding damage to the motor.

[0089] In some optional embodiments, the device further includes a determining unit, a fourth control unit, and a fifth control unit. The determining unit is used to collect the current of the phase preceding the target phase to obtain the first phase current, calculate the sum of the first phase current and the target phase current to obtain the sum of phase currents, and determine the negative sum of the phase currents as the current of the next phase following the target phase to obtain the second phase current. The fourth control unit is used to control the permanent magnet synchronous motor to be in a short-circuit braking stage when the first phase current or the second phase current is less than the preset current. The fifth control unit is used to control the upper and lower bridges of the three phases to turn off when the first phase current or the second phase current is greater than or equal to the preset current, so as to shut down the permanent magnet synchronous motor. This device calculates the current of each phase through the above steps, thus monitoring the current of each phase and promptly shutting off the motor when the current exceeds the preset current.

[0090] Specifically, the three phases of the motor are represented by phases A, B, and C. The sum of the currents in the three phases is 0, and the predetermined order is phase A, phase B, and phase C. Assuming the current cycle switching state is 1 (state = 1), then the duty cycle of the upper bridge of phase A (the target phase) is 2%, and the duty cycle of the lower bridge is 98%. During this switching cycle, when the upper bridge of phase A is turned on, the phase A current flows through the sampling resistor. The controller collects the phase A current and uses the sampled value from the previous state: the phase C current (the first phase current), and calculates the phase B current (the second phase current) using the fact that the sum of the three phase currents is 0. In the next cycle, the switching state is 2 (state = 2), and phase B is the target phase. Then, the duty cycle of the upper bridge of phase B is 2%, and the duty cycle of the lower bridge is 98%. During this switching cycle, when the upper bridge of phase B is turned on, the phase B current flows through the sampling resistor. The controller collects the phase B current and uses the sampled value from the previous state: the phase A current (the first phase current), and calculates the phase C current (the second phase current) using the fact that the sum of the three phase currents is 0. In the next cycle, the switching state is 3 (state = 3). Phase C is the target phase, with an upper bridge duty cycle of 2% and a lower bridge duty cycle of 98%. During this switching cycle, when the upper bridge of phase C is on, the phase C current flows through the sampling resistor. The controller collects the phase C current and uses the sampled value from the previous state: the phase B current (first phase current). It then calculates the phase A current (second phase current) using the fact that the sum of the three phase currents is 0. This cycle continues until the shutdown control ends. From the above analysis, it can be concluded that the controller can detect the three-phase current amplitude after only 3 switching cycles. If the amplitude of any phase current is greater than the preset current I... limit When the current is at the set point, turn off the switch; otherwise, enable the switch to limit the peak current of the motor to near the preset current. In order to better limit the actual current to near the preset current, the control cycle Ts should be minimized as much as possible.

[0091] To accurately obtain the timing control signal of the target moment of the target phase within the current cycle, the acquisition unit includes a first acquisition module and a second acquisition module. The first acquisition module is used to acquire the one-to-one mapping relationship between time and pulse signals within the current cycle, wherein the pulse signals include high-level signals and low-level signals, where the high-level signal indicates conduction and the low-level signal indicates deactivation. The second acquisition module is used to determine the midpoint of the time period corresponding to the high-level signal as the target moment and acquire the timing control signal of the target moment. By determining the midpoint as the target moment, the device can accurately acquire the timing control signal corresponding to the target moment.

[0092] Specifically, taking phase A as an example, the bus current when the upper bridge is turned on is analyzed. The current flowing into the motor is defined as positive, and the current flowing out of the motor is defined as negative. When the phase A current is positive and the upper bridge is turned on, the bus current flows into the motor, and at this time the bus capacitor discharges. When the phase A current is negative and the upper bridge is turned on, the phase A current charges the bus capacitor through the anti-parallel diode of the switching tube 1. The amplitude of the charging and discharging current is the amplitude of the phase A current |Ia|. Let the midpoint time of the upper bridge conduction pulse width in switch state 1 be t1, that is, the target time, let the midpoint time of the upper bridge conduction pulse width in switch state 2 be t2, let the midpoint time of the upper bridge conduction pulse width in switch state 3 be t3, and t1<t2<t3, the shutdown control call time interval T s =t2-t1=t3-t2, if T s is sufficiently small, for the three-phase currents of the motor: Ia(t1)+Ib(t2)+Ic(t3)=0, that is, the charging current and the discharging current of the bus capacitor are balanced, the charging energy and the discharging energy are equivalent, and the bus voltage will not change.

[0093] In some optional embodiments, the above apparatus further includes a sixth control unit, configured to control the upper bridges of the two phases other than the target phase in the three phases of the permanent magnet synchronous motor to be turned off, and control the lower bridges of the two phases other than the target phase in the three phases to be turned on. The apparatus controls the upper bridges of the remaining two phases to be turned off and the lower bridges to be turned on, which can reduce the pumped-up voltage.

[0094] In the specific implementation process, in order to prevent the pumped-up voltage from being too high, assuming that the switch state of the current cycle is 1 (state=1), the duty cycle of the upper bridge of phase A is 2%, the duty cycle of the lower bridge is 98%, the duty cycles of the upper bridges of phase B and phase C are 0%, and the duty cycles of the lower bridges are 100%; the switch state of the next cycle is 2 (state=2), the duty cycle of the upper bridge of phase B is 2%, the duty cycle of the lower bridge is 98%, the duty cycles of the upper bridges of phase A and phase C are 0%, and the duty cycles of the lower bridges are 100%; the switch state of the next cycle is 3 (state=3), the duty cycle of the upper bridge of phase C is 2%, the duty cycle of the lower bridge is 98%, the duty cycles of the upper bridges of phase A and phase B are 0%, and the duty cycles of the lower bridges are 100%. That is, the upper bridge is turned off, and the lower bridge is turned on.

[0095] The present application provides the d-q axis current expression of surface-mounted and interior permanent magnet synchronous motors under the steady-state short-circuit condition:

[0096]

[0097] where w is the electrical angular frequency of the motor, is the flux linkage of the motor, Lq is the quadrature axis inductance of the motor, Ld is the direct axis inductance of the motor, and R is the phase resistance of the motor. When w×Ld>>R, the amplitude of the d-q axis current is approximately:

[0098]

[0099] The phase current amplitude Is is:

[0100]

[0101] Therefore, the phase current amplitude under steady state is independent of the motor speed.

[0102] The control device for the aforementioned permanent magnet synchronous motor includes a processor and a memory. The acquisition unit, the first control unit, and the second control unit, etc., are all stored as program units in the memory. The processor executes these program units stored in the memory to achieve the corresponding functions. All of the above modules reside in the same processor; alternatively, the modules may be located in different processors in any combination.

[0103] The processor contains a kernel, which retrieves the corresponding program units from memory. One or more kernels can be configured, and adjusting kernel parameters can address the problem of the inability to collect phase current when a permanent magnet synchronous motor is running at high speed, a problem present in existing technologies.

[0104] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0105] This invention provides a permanent magnet synchronous motor system, including a permanent magnet synchronous motor, a bus capacitor, a sampling resistor, a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch. The permanent magnet synchronous motor has three phases. Each switch is connected in parallel with a diode. The first switch and the second switch are connected in series through a first node to form a first branch. The third switch and the fourth switch are connected in series through a second node to form a second branch. The fifth switch and the sixth switch are connected in series through a third node to form a third branch. The first terminal of the bus capacitor is connected to the first terminal of the first branch and the second branch. The first end of the first branch is electrically connected to the first end of the third branch, the second end of the first branch, the second end of the second branch, and the second end of the third branch are electrically connected, the second end of the bus capacitor is electrically connected to the first end of the sampling resistor, the second end of the sampling resistor is electrically connected to the second end of the second branch, the first phase of the permanent magnet synchronous motor is electrically connected to the first node, the second phase of the permanent magnet synchronous motor is electrically connected to the second node, the third phase of the permanent magnet synchronous motor is electrically connected to the third node, and the permanent magnet synchronous motor includes a program for executing any of the control methods of the permanent magnet synchronous motor.

[0106] This invention provides a computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform the control method for the permanent magnet synchronous motor.

[0107] This invention provides a device that includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps of the control method for the permanent magnet synchronous motor described above.

[0108] The devices mentioned in this article can be servers, PCs, tablets, mobile phones, etc.

[0109] This application also provides a computer program product that, when executed on a data processing device, is adapted to perform a program that initializes a control method step having at least the above-described permanent magnet synchronous motor.

[0110] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0111] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0112] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0113] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0114] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0115] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0116] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0117] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0118] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0119] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0120] 1) The control method for the permanent magnet synchronous motor of this application controls the upper and lower bridges of the target phase to conduct according to a first duty cycle and a second duty cycle, respectively, through a timing control signal. After conduction, the target phase current is collected. If the target phase current is less than a preset current, the permanent magnet synchronous motor is controlled to be in a short-circuit braking state. If the target phase current is greater than or equal to the preset current, the three-phase upper and lower bridges are turned off, causing the current of the permanent magnet synchronous motor to decrease and preventing excessive current from causing demagnetization of the air conditioner compressor motor. Compared with the prior art, where a single resistor cannot collect the target phase current when the permanent magnet synchronous motor is running at high speed, thus making it impossible to monitor whether the target phase current is too large, this application can control the target phase to conduct according to the timing control signal and collect the target phase current. Therefore, it can solve the problem in the prior art that a single resistor cannot collect the target phase current when the motor is short-circuited, achieving the effect of timely collection of the target phase current and monitoring the motor's operating status.

[0121] 2) The control device for the permanent magnet synchronous motor of this application controls the upper and lower bridges of the target phase to conduct according to the first and second duty cycles, respectively, through timing control signals. After conduction, the target phase current is collected. When the target phase current is less than the preset current, the permanent magnet synchronous motor is controlled to be in a short-circuit braking state. When the target phase current is greater than or equal to the preset current, the three-phase upper and lower bridges are turned off, causing the current of the permanent magnet synchronous motor to decrease and preventing excessive current from causing demagnetization of the air conditioner compressor motor. Compared with the prior art, where a single resistor cannot collect the target phase current when the permanent magnet synchronous motor is running at high speed, thus failing to monitor whether the target phase current is too large, this application can control the target phase to conduct according to the timing control signal and collect the target phase current. Therefore, it can solve the problem in the prior art that a single resistor cannot collect the target phase current when the motor is short-circuited, achieving the effect of timely collection of the target phase current and monitoring the motor's operating status.

[0122] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A control method for a permanent magnet synchronous motor, characterized in that, The permanent magnet synchronous motor is electrically connected to the inverter, which drives the permanent magnet synchronous motor. The inverter includes three phases, each phase including an upper bridge and a lower bridge, comprising: Obtain the one-to-one mapping relationship between time and pulse signal within the current period, wherein the pulse signal includes a high-level signal and a low-level signal, the high-level signal indicating conduction and the low-level signal indicating deactivation; determine the midpoint of the time period corresponding to the high-level signal as the target time, and obtain the timing control signal of the target time, wherein the timing control signal is a signal used to control whether the target phase is turned on; When the timing control signal indicates that the target phase is to be turned on, the upper bridge of the target phase is controlled to be turned on according to a first duty cycle, and the lower bridge of the target phase is controlled to be turned on according to a second duty cycle, wherein the first duty cycle is 2% and the second duty cycle is 98%; The current of the target phase is collected to obtain the target phase current. When the target phase current is less than the preset current, the permanent magnet synchronous motor is controlled to be in a short-circuit braking state. When the target phase current is greater than or equal to the preset current, the upper bridge and the lower bridge of the three phases are controlled to be turned off so that the permanent magnet synchronous motor is turned off.

2. The control method according to claim 1, characterized in that, Controlling the upper bridge of the target phase to conduct according to a first duty cycle includes: Obtain the current of the target phase in the previous cycle to obtain the current of the previous target phase, wherein the previous cycle is the cycle adjacent to the current cycle and preceding the current cycle; When the current of the previous target phase is less than 0, the upper bridge of the target phase is controlled to conduct according to the first duty cycle.

3. The control method according to claim 2, characterized in that, The method further includes: When the previous target phase current is greater than 0, the dead time is obtained, and the first duty cycle is added to the dead time by a predetermined multiple to obtain the third duty cycle; The upper bridge of the target phase is controlled to conduct according to the third duty cycle.

4. The control method according to claim 1, characterized in that, The timing control signal controls the conduction of each phase in a predetermined sequence within each cycle. After acquiring the current of the target phase and obtaining the target phase current, the method further includes: The current of the phase preceding the target phase is collected to obtain the first phase current. The sum of the first phase current and the target phase current is calculated to obtain the sum of phase currents. The negative sum of the phase currents is determined as the current of the next phase of the target phase to obtain the second phase current. When the first phase current or the second phase current is less than the preset current, the permanent magnet synchronous motor is controlled to be in the short-circuit braking state; When the first phase current or the second phase current is greater than or equal to the preset current, the upper bridge and the lower bridge of the three phases are controlled to turn off, so as to turn off the permanent magnet synchronous motor.

5. The control method according to claim 1, characterized in that, Obtain the timing control signal for the target phase within the current period, including: Obtain the one-to-one mapping relationship between time and pulse signal within the current period, wherein the pulse signal includes a high-level signal and a low-level signal, the high-level signal indicating conduction and the low-level signal indicating deactivation; The midpoint of the time period corresponding to the high-level signal is determined as the target time, and the timing control signal of the target time is obtained.

6. The control method according to claim 1, characterized in that, After controlling the upper bridge of the target phase to conduct according to a first duty cycle and controlling the lower bridge of the target phase to conduct according to a second duty cycle, the method further includes: The upper bridge of the two phases other than the target phase in the three phases of the permanent magnet synchronous motor is turned off, and the lower bridge of the two phases other than the target phase in the three phases is turned on.

7. A control device for a permanent magnet synchronous motor, characterized in that, The permanent magnet synchronous motor is electrically connected to the inverter, which drives the permanent magnet synchronous motor. The inverter includes three phases, each phase including an upper bridge and a lower bridge, comprising: The acquisition unit is used to acquire a one-to-one mapping relationship between time and pulse signals within the current cycle, wherein the pulse signals include high-level signals and low-level signals, the high-level signals indicating conduction and the low-level signals indicating deactivation; the midpoint of the time period corresponding to the high-level signal is determined as the target time, and the timing control signal of the target time is acquired, wherein the timing control signal is a signal characterizing the conduction of each phase of the permanent magnet synchronous motor; A first control unit is configured to, when the timing control signal indicates that the target phase is turned on, control the upper bridge of the target phase to conduct according to a first duty cycle, and control the lower bridge of the target phase to conduct according to a second duty cycle, wherein the first duty cycle is 2% and the second duty cycle is 98%; The second control unit is used to collect the current of the target phase, obtain the target phase current, control the permanent magnet synchronous motor to be in a short-circuit braking state when the target phase current is less than the preset current, and control the upper bridge and lower bridge of the three phases to shut down the permanent magnet synchronous motor when the target phase current is greater than or equal to the preset current.

8. A permanent magnet synchronous motor system, characterized in that, include: The system comprises a permanent magnet synchronous motor, a bus capacitor, a sampling resistor, a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch. The permanent magnet synchronous motor has three phases. Each switch is connected in parallel with a diode. The first switch and the second switch are connected in series through a first node to form a first branch. The third switch and the fourth switch are connected in series through a second node to form a second branch. The fifth switch and the sixth switch are connected in series through a third node to form a third branch. The first terminal of the bus capacitor is electrically connected to the first terminal of the first branch, the first terminal of the second branch, and the first terminal of the third branch. The second terminal of the first branch, the second terminal of the second branch, and the second terminal of the third branch are also electrically connected. The second terminal of the bus capacitor is electrically connected to the first terminal of the sampling resistor. The second terminal of the sampling resistor is electrically connected to the second terminal of the second branch. The first phase of the permanent magnet synchronous motor is electrically connected to the first node. The second phase of the permanent magnet synchronous motor is electrically connected to the second node. The third phase of the permanent magnet synchronous motor is electrically connected to the third node. The permanent magnet synchronous motor includes a program for executing the control method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device on which the computer-readable storage medium is located to perform the control method according to any one of claims 1 to 6.

10. An electronic device, characterized in that, include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including a control method for performing any one of claims 1 to 6.

Images