Constant speed control and constant power control of permanent magnet synchronous motor

Abstract

The motor controller includes: a current controller configured to generate a control signal for driving a permanent magnet synchronous motor (PMSM), wherein the current controller is configured to measure voltage information and current information of the PMSM; a power constant controller configured to receive the voltage information and the current information, and generate a first target speed based on a target power of the PMSM and based on the voltage information and the current information; a first signal generator configured to generate a second target speed; and a speed constant controller coupled between the power constant controller and the current controller, wherein the speed constant controller is configured to switchably receive the first target speed and the second target speed, and adjust the motor speed of the PMSM based on the received first target speed or the received second target speed.

Description

Technical Field

[0001] The present disclosure generally relates to apparatus and methods for achieving constant speed control and constant power control of a permanent magnet synchronous motor (PMSM), and more particularly to a PMSM utilizing sensorless field oriented control (FOC). Background Art

[0002] Motor controllers use motor control algorithms that implement constant speed control or constant power control to control permanent magnet synchronous motors (PMSMs). PMSMs can be used in fan motors, such as those used in vacuum cleaners, exhaust fans, fume extraction fans, and other similar applications. However, there are at least four problems.

[0003] First, constant speed control cannot maintain a constant airflow from the fan when the air inlet has changed. For example, the air inlet of a vacuum cleaner may become partially or completely blocked.

[0004] Second, because the speed is held constant, if the load increases, the motor power will increase rapidly, so constant speed control does not protect the battery power of the motor. For example, the load may increase in response to the air intake opening more than during normal operation.

[0005] Third, the frequency bandwidth of typical constant power control is usually narrow. As a result, the dynamic response is slow. If, as in the case of a vacuum cleaner, the motor needs to start quickly, the constant power control may not meet this requirement because the startup speed is too slow.

[0006] Fourth, the general power constant control only controls the motor power, which is also the output power of the inverter, but it cannot reflect the input power to protect the battery power.

[0007] Therefore, an improved device with power constant control implemented in a PMSM using sensorless field-oriented control (FOC) that can solve these problems is desired.

[0008] Problems can also arise with vacuum cleaners and other suction equipment when the inlet of the vacuum cleaner or suction device becomes blocked by one or more objects. This blocked inlet can lead to numerous other problems, including burnout of motors and circuit boards, which can reach high temperatures without effective cooling airflow. Furthermore, without airflow, dust, dirt, and other debris cannot be vacuumed.

[0009] Therefore, an improved device with constant power control would be desirable with the added ability to automatically (ie, without user intervention) remove inlet obstructions during runtime of the motor. Summary of the Invention

[0010] One or more embodiments provide a motor controller configured to drive a permanent magnet synchronous motor (PMSM) using sensorless field-oriented control (FOC). The motor controller includes: a current controller configured to generate a control signal for driving the PMSM, wherein the current controller is configured to measure voltage information and current information of the PMSM; a power constant controller configured to receive the voltage information and the current information and generate a first target speed based on a target power of the PMSM and based on the voltage information and the current information; a first signal generator configured to generate a second target speed; a speed constant controller coupled between the power constant controller and the current controller, wherein the speed constant controller is configured to switchably receive the first target speed and the second target speed and adjust the motor speed of the PMSM based on the received first target speed or the received second target speed; a first switch configured to switchably couple the speed constant controller to the power constant controller in a first switching state to receive the first target speed, or to couple the speed constant controller to the first signal generator in a second switching state to receive the second target speed; and a first switch controller configured to control the switching state of the first switch.

[0011] One or more embodiments provide a method for driving a PMSM using sensorless field-controlled optical (FOC) control. The method includes: generating a control signal for driving the PMSM by a current controller; measuring voltage information and current information of the PMSM by the current controller; generating a first target speed by a constant power controller based on a target power of the PMSM and based on the voltage information and the current information; generating a second target speed by a first signal generator; switchably receiving the first and second target speeds by a constant speed controller coupled between the constant power controller and the current controller; adjusting the motor speed of the PMSM based on the received first target speed or the received second target speed by the constant speed controller; switchably coupling the constant speed controller to the constant power controller in a first switching state to receive the first target speed, or coupling the constant speed controller to the first signal generator in a second switching state to receive the second target speed by a first switch; and controlling the switching state of the first switch by a first switch controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Embodiments are described herein with reference to the accompanying drawings.

[0013] Figure 1A is a schematic block diagram illustrating a motor control actuator of a power semiconductor device according to one or more embodiments;

[0014] Figure 1Bis a schematic diagram illustrating a power inverter utilizing single shunt current sensing according to one or more embodiments;

[0015] Figure 2A is a diagram illustrating a speed constant control feature according to one or more embodiments;

[0016] Figure 2B is a diagram illustrating a power constant control feature according to one or more embodiments;

[0017] Figure 3A-1 and Figure 3A-2 is a schematic block diagram of a motor control algorithm implemented by a motor controller according to one or more embodiments;

[0018] Figure 3B is a schematic block diagram of a fast startup logic module included in a motor control algorithm and used to implement a constant speed control mode and a constant power control mode according to one or more embodiments;

[0019] Figure 3C is a schematic block diagram of a fail-safe logic module included in a motor control algorithm and used to implement a fail-safe state during a constant power control mode according to one or more embodiments;

[0020] Figure 4 FIGURE 1 illustrates a fitted curve (ie, a normal speed fitting curve) according to one or more embodiments, wherein a normal motor speed is fitted to a target power;

[0021] Figure 5 is a diagram illustrating a motor rapid start process according to one or more embodiments compared to a conventional constant power start process;

[0022] Figure 6 is a graph illustrating motor speed and input power of the inverter 1 according to a fail-safe state of the motor controller 6 according to one or more embodiments;

[0023] Figure 7 is a flow chart of a fail-safe logic flow implemented by the fail-safe logic module 60 according to one or more embodiments. DETAILED DESCRIPTION

[0024] Hereinafter, details are set forth to provide a more thorough explanation of the exemplary embodiments. However, it will be apparent to those skilled in the art that the embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form or schematic form rather than in detail to avoid obscuring the embodiments. In addition, unless otherwise specifically noted, the features of the different embodiments described below may be combined with each other.

[0025] In addition, in the following description, equivalent or similar reference numerals are used to indicate equivalent or similar elements having equivalent or similar functionality. Since identical or functionally equivalent elements are given the same reference numerals in the drawings, repeated descriptions of elements having the same reference numerals may be omitted. Therefore, the descriptions provided for elements having the same or similar reference numerals are interchangeable.

[0026] In this regard, directional terms such as "top," "bottom," "below," "above," "front," "back," "backward," "leading to," "rearward," etc., may be used with reference to the orientation of the accompanying drawings being described. Because portions of the embodiments may be positioned in many different orientations, the directional terms are used for illustrative purposes and are in no way limiting. It is understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the claims. Therefore, the following detailed description should not be taken in a limiting sense.

[0027] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements. Other words used to describe the relationship between elements (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.) should be interpreted in a similar manner.

[0028] In the embodiments shown in the drawings or described herein, any direct electrical connection or coupling, i.e., any connection or coupling without additional intermediate elements, may also be achieved through an indirect connection or coupling, i.e., a connection or coupling with one or more additional intermediate elements, and vice versa, as long as the general purpose of the connection or coupling (e.g., to transmit a signal or to transmit information) is substantially maintained. Features from different embodiments may be combined to form other embodiments. For example, unless otherwise indicated, changes or modifications described with respect to one embodiment may also apply to other embodiments.

[0029] The term "substantially" may be used herein to describe small manufacturing tolerances (eg, within 5%) that are considered acceptable in the industry without departing from aspects of the embodiments described herein.

[0030] A sensor may refer to a component that converts a physical quantity to be measured into an electrical signal (eg, a current signal or a voltage signal). The physical quantity may be, for example, a current or voltage across a shunt resistor in a single shunt resistor system.

[0031] Signal processing circuitry and / or signal conditioning circuitry can receive one or more signals from one or more components and perform signal conditioning or processing thereon. As used herein, signal conditioning refers to manipulating a signal in such a way that the signal meets the requirements of the next stage for further processing. Signal conditioning can include conversion from analog to digital (e.g., via an analog-to-digital converter), amplification, filtering, conversion, biasing, range matching, isolation, and any other process required to make the signal suitable for processing after conditioning.

[0032] Thus, the signal processing circuitry may include an analog-to-digital converter (ADC) that converts an analog signal from one or more sensor elements into a digital signal. The signal processing circuitry may also include a digital signal processor (DSP) that performs some processing on the digital signal.

[0033] Modern devices in automotive, consumer, and industrial applications rely on power semiconductor devices for many functions, such as converting electrical energy and driving electric motors. For example, insulated gate bipolar transistors (IGBTs), metal oxide semiconductor field effect transistors (MOSFETs), and diodes, to name a few, have been used in a variety of applications, including but not limited to switches in power supplies and power converters.

[0034] A power semiconductor device typically includes a semiconductor structure configured to conduct a load current along a load current path between two load terminal structures of the device. Furthermore, the load current path can be controlled by means of a control electrode (sometimes referred to as a gate electrode). For example, upon receiving a corresponding control signal from, for example, a driver unit, the control electrode can set the power semiconductor device to one of an on-state and an off-state. The control signal can be a voltage signal or a current signal having a controlled value.

[0035] A power transistor is a power semiconductor device that can be used to drive a load current. For example, an IGBT is turned "on" or "off" by activating and deactivating its gate terminal. Applying a positive input voltage signal across the gate and emitter will keep the device in its "on" state, while making the input gate signal zero or slightly negative will turn it "off". There are turn-on and turn-off processes for turning on and off power transistors. During the turn-on process, a gate driver integrated circuit (IC) can be used to provide (source) a gate current (i.e., a turn-on current) to the gate of the power transistor in order to charge the gate to a sufficient voltage to turn on the device. Conversely, during the turn-off process, a gate driver IC is used to draw (sink) a gate current (i.e., a turn-off current) from the gate of the power transistor in order to sufficiently discharge the gate to turn off the device. According to a pulse width modulation (PWM) scheme, a current pulse can be output from the gate driver IC as a control signal. Therefore, during a PWM cycle for controlling the power transistor, the control signal can be switched between an on current level and an off current level. This in turn charges and discharges the gate voltage to switch the power transistor on and off accordingly.

[0036] In particular, the gate of the power transistor is a capacitive load, and the on-current (i.e., gate source current) and the off-current (i.e., gate sink current) are specified as initial currents when a switching event is initiated. During the off-event, after a short period of time (short compared to the PWM period), the gate current decreases and reaches zero when the gate reaches 0 V. During the on-event, after a short period of time (short compared to the PWM period), the gate current decreases and reaches zero when the gate reaches 15 V.

[0037] The transistors may include insulated gate bipolar transistors (IGBTs) and metal oxide semiconductor field effect transistors (MOSFETs) (e.g., silicon MOSFETs or silicon carbide MOSFETs). Although IGBTs may be used as examples in the following embodiments, it should be understood that MOSFETs may be used in place of IGBTs, and vice versa. In this context, when MOSFETs are used in place of IGBTs, the collector of the IGBT in any of the examples described herein may be replaced by the drain of the MOSFET, the emitter of the IGBT may be replaced by the source of the MOSFET, and the collector-emitter voltage V CE The MOSFET drain-source voltage V DS Therefore, any IGBT module can be replaced by a MOSFET module and vice versa.

[0038] Certain embodiments described herein relate to, but are not limited to, power semiconductor devices that can be used within a power converter or power supply. Thus, in one embodiment, a power semiconductor device can be configured to carry a load current to be supplied to a load and / or, in turn, a load current provided by a power supply. For example, the semiconductor device can include one or more power semiconductor cells, such as a monolithically integrated diode cell and / or a monolithically integrated transistor cell. Such a diode cell and / or such a transistor cell can be integrated into a power semiconductor module.

[0039] In the field of power electronics, power semiconductor devices are commonly used, which include transistors that are suitably connected to form a half-bridge. For example, a half-bridge can be used to drive an electric motor or a switched-mode power supply.

[0040] For example, a multiphase inverter is configured to provide multiphase power by supplying a multiphase load (e.g., a three-phase motor). For example, three-phase power involves three symmetrical sinusoidal waves that are 120 electrical degrees out of phase with each other. In a symmetrical three-phase power system, each of the three conductors carries an alternating current (AC) with the same frequency and voltage amplitude relative to a common reference, but with a phase difference of one-third of the cycle. Due to the phase difference, the voltage on any one conductor reaches its peak value one-third of the cycle after one of the other conductors and one-third of the cycle before the remaining conductor. This phase delay delivers constant power to a balanced linear load. A rotating magnetic field can also be generated in the motor.

[0041] In a three-phase system feeding a balanced, linear load, the sum of the instantaneous currents in the three conductors is zero. In other words, the current in each conductor is equal in magnitude to the sum of the currents in the other two conductors, but of opposite sign. The return path for the current in any phase conductor is through the other two phase conductors. The instantaneous currents result in a current space vector.

[0042] A three-phase inverter includes three inverter legs, each for each of the three phases, and each inverter leg is connected to a direct current (DC) voltage source in parallel with each other. Each inverter leg includes a pair of transistors, such as a pair of transistors arranged in a half-bridge configuration for converting DC to AC. In other words, each inverter leg includes two complementary transistors (i.e., a high-side transistor and a low-side transistor) connected in series, and they are turned on and off complementarily to each other to drive the phase load. However, a multiphase inverter is not limited to three phases and may include two or more phases, each having an inverter leg.

[0043] Figure 1A1 is a schematic block diagram illustrating a motor control actuator 100 of a power semiconductor device according to one or more embodiments. Specifically, the motor control actuator 100 includes a power inverter 1 and an inverter control unit 2. The inverter control unit 2 functions as a motor control unit and may therefore also be referred to as a motor controller or motor control IC. The motor control unit may be a single-chip IC or may be divided into a microcontroller and gate driver on two or more ICs.

[0044] The motor control actuator 100 is also coupled to a three-phase motor M including three phases U, V, and W. The power inverter 1 is a three-phase voltage generator configured to provide three-phase power by supplying a three-phase voltage to drive the motor M. It will be further appreciated that the power inverter 1 and the inverter control unit 2 may be placed on the same circuit board or on separate circuit boards.

[0045] Deviations in both amplitude and phase can result in power and torque losses in the motor M. Therefore, the motor control actuator 100 can be configured to monitor and control the amplitude and phase of the voltage supplied to the motor M in real time to ensure that proper current balance is maintained based on a feedback control loop. Open-loop motor control units also exist and can be implemented.

[0046] A power inverter 1 for a three-phase motor M includes a switch array of six transistor modules 3u+, 3u-, 3v+, 3v-, 3w+ and 3w- (collectively referred to as transistor modules 3) arranged in complementary pairs. Each complementary pair constitutes an inverter branch that supplies a phase voltage to the three-phase motor M. Therefore, each inverter branch includes an upper (high-side) transistor module 3 and a lower (low-side) transistor module 3. Each transistor module may include a power transistor and may also include a diode (not shown). Therefore, each inverter branch includes an upper transistor and a lower transistor. Load current paths U, V and W extend from the output of each inverter branch (i.e., the output of each half bridge) located between the complementary transistors and are configured to be coupled to a load, such as a motor M. The power inverter 1 is coupled to a DC power source 4 (e.g., a battery or a diode bridge rectifier) ​​and to an inverter control unit 2.

[0047] In this example, the inverter control unit 2 includes a motor control circuit and a gate driver circuit for controlling the switch array. In some examples, the inverter control unit 2 can be monolithic, where the motor control circuit and the gate driver circuit are integrated onto a single bare die. In other examples, the motor control circuit and the gate driver circuit can be divided into separate ICs. A "monolithic" gate driver is a gate driver on a single silicon chip and can further be made using specific high voltage (HV) technology. In addition, the gate driver IC can be integrated on the power inverter 1.

[0048] The motor controller performs the motor control function of the motor control actuator 100 in real time and transmits PWM control signals to the gate driver. The motor control function can include controlling a permanent magnet motor or controlling an induction motor, and can be configured as sensorless control that does not require rotor position sensing, such as in the case of sensor-based control using Hall sensors and / or encoder devices. Alternatively, the motor control function can include a combination of sensor-based control (e.g., used at lower rotor speeds) and sensorless control (e.g., used at higher rotor speeds).

[0049] For example, the inverter control unit 2 includes a controller and driver unit 5, which includes a microcontroller unit (MCU) 6 as a motor controller, and a gate driver 7 for generating a driver signal for controlling the transistor of each transistor module 3. Therefore, the load current paths U, V, and W can be controlled by the controller and driver unit 5 by controlling the control electrodes (i.e., gate electrodes) of the transistors 3. For example, when receiving a PWM control signal from the microcontroller, the gate driver IC can set the corresponding transistor to be in one of a conducting state (i.e., an on state) or a cut-off state (i.e., an off state).

[0050] The gate driver IC can be configured to receive instructions including power transistor control signals from the microcontroller and turn on or off the corresponding transistor 3 according to the received instructions and control signals. For example, during the turn-on process of the corresponding transistor 3, the gate driver IC can be used to provide (source) a gate current to the gate of the corresponding transistor 3 to charge the gate. Conversely, during the turn-off process, the gate driver IC can be used to draw (sink) a gate current from the gate of the transistor 3 to discharge the gate.

[0051] The inverter control unit 2 or controller and driver unit 5 itself may include a PWM controller, ADC, DSP and / or clock source (i.e., timer or counter) used in implementing a PWM scheme for controlling the state of each transistor and, ultimately, each phase current provided on the corresponding load current paths U, V and W.

[0052] In particular, the microcontroller 6 of the controller and driver unit 5 can use a motor control algorithm such as a field-oriented control (FOC) algorithm to provide current control in real time for each phase current output to a multi-phase load such as a multi-phase motor. Therefore, the field-oriented control loop can be referred to as a current control loop. The motor speed can be further controlled by adding a speed constant control loop that provides speed constant control on top of the FOC control. Therefore, the FOC (i.e., the current control loop) can be considered an inner control loop, while the speed constant control loop can be considered an outer control loop. In addition, the motor power can be further controlled by a power constant control loop on top of the speed constant control loop, and in turn, the motor speed can be controlled. Therefore, at least with respect to the current control loop and the speed constant control loop, the power constant control loop can be considered the outermost control loop. In other words, the current control loop can be considered an inner control loop, the speed constant control loop can be considered an intermediate control loop, and the power constant control loop can be considered an outer control loop.

[0053] During motor control (i.e., during operation of the motor), the current control loop and the speed constant control loop always remain activated or enabled. Similarly, the power constant control loop can remain activated or enabled during motor control. However, the power constant control loop can also be switchably activated / deactivated (enabled / disabled) during motor control. In the instance when the power constant control loop is activated, the controller and driver unit 5 are considered to be in the power constant control mode, even if the speed constant control loop is also activated. In the case when the power constant control loop is deactivated, the controller and driver unit 5 are considered to be in the speed constant control mode.

[0054] In some cases, a fourth control loop (eg, a position control loop), also outside of the constant speed control loop, may be used to control the motor position.

[0055] For example, during FOC, the motor phase current should be measured so that the exact rotor position can be determined in real time. To achieve the determination of the motor phase current, the microcontroller 6 can employ an algorithm that uses single-shunt current sensing (e.g., space vector modulation (SVM), which is also known as space vector pulse width modulation (SVPWM)).

[0056] Furthermore, the switches 3 (i.e., transistors) of the power inverter 1 are controlled so that not both switches in the same inverter branch are conducting at any one time, otherwise the DC power supply would be short-circuited. This requirement can be met by complementary operation of the switches 3 within the inverter branches according to the motor control algorithm.

[0057] Figure 1B FIG1 is a schematic diagram illustrating a power inverter 1 utilizing single shunt current sensing according to one or more embodiments. In particular, the power inverter 1 includes a shunt resistor Rs placed on the negative DC link of the power inverter 1. The transistor 3 u+ , 3 u- , 3 v+ , 3 v- , 3 w+ and 3 w- are represented as switches, and the motor M is shown with one winding for each of its phases. Here, UO represents the line-to-neutral voltage from the bridge midpoint U to the motor neutral point O; UN represents the U-bridge voltage from the bridge midpoint U to the negative bus supply rail N; UV represents the line-to-line voltage from U phase to V phase; VW represents the line-to-line voltage from V phase to W phase; and WV represents the line-to-line voltage from W phase to V phase.

[0058] Figure 1A The microcontroller 6 in can receive samples of the current obtained from the shunt resistor Rs and then reconstruct the three-phase current in real time using an algorithm (i.e., software). For example, SVPWM is an algorithm based on vector control that requires sensing of the three motor phase currents. By using a single shunt resistor Rs, the DC link current pulses are sampled at precise time intervals. The voltage drop across the shunt resistor Rs can be amplified by an operational amplifier inside the inverter control unit 2 and shifted up by 1.65V, for example. The resulting voltage can be converted by an ADC inside the inverter control unit 2. Based on the actual combination of switches, the three-phase current of the motor M is reconstructed using the SVPWM algorithm. The ADC can measure the DC link current during the active vector of the PWM cycle. Two-phase current measurements are available in each sector. Since the sum of the three winding currents is zero, the third phase current value can be calculated.

[0059] SVPWM itself is an algorithm for real-time PWM control. It is used to create AC waveforms and can be used to drive a three-phase AC-powered motor at variable speed from a DC power source using multiple switching transistors. Although the examples herein are described in the context of a three-phase motor, the examples are not limited thereto and can be applied to any load scenario.

[0060] Additionally, it will be understood that implementations other than a single shunt resistor may be used for current sensing, and other motor control algorithms may be used to control the load, and the embodiments described herein are not limited in this regard.

[0061] Figure 2A FIG. 1 is a graph illustrating a velocity constant control feature according to one or more embodiments. Specifically, the graph illustrates a velocity constant control feature for airflow (m) with respect to inlet opening (%). 3 The speed control maintains the motor speed at a constant value regardless of load changes, which may occur in response to changes in the air inlet.

[0062] Figure 2B FIG. 1 is a graph illustrating a power constant control feature according to one or more embodiments. Specifically, the graph illustrates a power constant control feature for airflow (m) with respect to inlet opening (%). 3 The motor speed (rpm / s), current (A), and power (W) are arbitrary values, where 0% corresponds to a closed or blocked inlet and 100% corresponds to a fully open or unblocked inlet. The motor power is also the same as the output power of inverter 1. Power control maintains the motor power at a constant value regardless of load changes, which may occur in response to changes in the air inlet.

[0063] According to one or more embodiments, in fan applications with constant-power control, airflow doesn't change much. When the air intake is reduced, the load current changes less than with constant-speed control. Here, the constant-power controller increases the output current to maintain constant power, which in turn increases the electronic torque and motor speed.

[0064] The described embodiment of power control can use the target power as the input power to the inverter. Thus, the power control controller controls the input power to the inverter and protects the battery. Furthermore, by combining speed control and power control in the manner described herein, when the motor is started, speed control can be used to quickly start the motor, and once the motor reaches a predetermined "normal" speed at the selected target power, the motor controller can switch the control mode to power control.

[0065] Figure 3A-1 and Figure 3A-2 is a schematic block diagram of a motor control algorithm 300 according to one or more embodiments. Figure 3Bis a schematic block diagram of a fast startup logic module included in the motor control algorithm 300 and used to implement a constant speed control mode and a constant power control mode according to one or more embodiments. Figure 3C is a schematic block diagram of a fail-safe logic module included in the motor control algorithm 300 and used to implement a fail-safe state in a constant power control mode according to one or more embodiments.

[0066] In particular, Figure 3A consists of two parts Figure 3A-1 and Figure 3A-2 The two parts are connected together at the corresponding boundary (A) to form the complete motor control algorithm 300. The motor control algorithm 300 can be implemented as firmware programmed into the motor controller 6 or by a combination of firmware and circuit components. The motor controller 6 itself can include one or more controllers.

[0067] Specifically, the motor control algorithm 300 includes Figure 1A The motor controller 6 shown in FIG. 1 implements a power constant control loop 11, a speed constant control loop 12 (i.e., sensorless FOC), a current control loop 13, and a power control enable block 14. Therefore, the motor controller 6 includes a power controller, a speed controller, and a current controller, which implement their respective control loops. Therefore, the power constant control loop 11 can be used interchangeably with the power controller 11, the speed constant control loop 12 can be used interchangeably with the speed controller 12, the current control loop 13 can be used interchangeably with the current controller 13, and the power control enable block 14 can be used interchangeably with the power constant control enable signal 14s. The power control enable block 14 itself is a controller device that is configured to switch the motor controller 6 to one of two operating modes including a power control mode or a speed control mode.

[0068] As used herein, Vq and Vd represent the stator q-axis voltage and d-axis voltage of the motor in the dq coordinate system, respectively. That is, Vq is the motor voltage component on the q-axis of the DQ coordinate system, and Vd is the motor voltage component on the d-axis of the DQ coordinate system. Similarly, Iq and Id represent the stator q-axis current and d-axis current of the motor in the DQ coordinate system, respectively. That is, Iq is the motor current component on the q-axis of the DQ coordinate system, and Id is the motor current component on the d-axis of the DQ coordinate system. In addition, each proportional-integral (PI) controller receives a proportional gain KP and an integral gain KI.

[0069] PI output = KPΔ + KI∫Δdt, Equation 1, Where Δ is the error or deviation between the actual measured value (PV) and the set point (SP).

[0070] Δ=SP–PV Equation 2.

[0071] The sensorless FOC software supports driving two types of permanent magnet synchronous motors (PMSMs): surface-mounted motors with constant air gaps and internally mounted motors with variable reluctance. The sensorless FOC algorithm structure is illustrated in FIG3A and follows a cascade control structure with an outer power constant control loop, an intermediate speed constant control loop, and an inner current control loop, each of which acts to change the motor winding voltage to drive the motor to a target power or target speed. If the output of the power control enable signal 14s is, for example, a logic high (i.e., "1"), the input TargetSpeed ​​of the speed constant control loop is connected to the output of the power constant control loop 11 via switch 63, and the power constant control loop implements power constant control. If the output of the power control enable signal 14s is a logic low (i.e., "0"), the input TargetSpeed ​​of the speed constant control loop is connected to an external digital or analog signal 15s (universal asynchronous receiver / transmitter (UART), variable speed pump (VSP), frequency, and duty cycle) via switch 63. In other words, according to the control of the power control enable block 14, the input of the speed ramp rate SpdRampRate block 21 is switchably connected to one of the two alternative paths via the switch 63. The external digital signal or analog signal 15s is generated by the external signal generator 15, which is configured to generate the external digital signal or analog signal 15s based on one or more input parameters related to setting the target speed of the motor.

[0072] The speed controller 12 calculates the motor torque required to follow the target speed (TargetSpeed). TargetSpeed ​​is a variable that sets the target speed of the motor. When the power control enable signal 14s is 1, the target speed (TargetSpeed) comes from the output of the power constant control loop 11. When the power control enable signal 14s is 0, the target speed (TargetSpeed) comes from an external digital signal or analog signal 15s. The target speed is a constant value; according to the speed ramp rate, the target speed is changed to the inclined boost value SpdRef by the speed ramp rate SpdRampRate block 21. The error generator 22 receives the SpdRef signal and the actual (measured) motor speed value MotorSpeed ​​(i.e., the estimated speed) from the flux estimator and phase-locked loop (PLL) unit 43, and generates a speed error ErrSpeed, which is the deviation between the SpdRef signal and the actual (estimated) motor speed.

[0073] The PI compensator 23 acts on the error ErrSpeed. The integral term forces the speed steady-state error to zero, while the proportional term improves the high-frequency response. The PI compensator gains KP and KI are adjusted depending on the motor and load characteristics to meet the target dynamic performance. The output of the PI compensator 23 is the torque current TrqRef, which is capable of maintaining the motor speed SpdRef. The limiting function block 24 applies one or more limiting functions to the output of the PI compensator 23. For example, the limiting function block 24 performs a motor limiting function MotorLim on the output of the PI compensator 23 to prevent integral windup and maintain the motor current within the maximum current of the motor. The limiting function block 24 performs a low speed limiting function LowSpeedLim on the output of the PI compensator 23 to limit the motor current to a low speed. The limiting function block 24 performs a regenerative current limiting function RegenLim on the output of the PI compensator 23 to limit the regenerative current of the motor.

[0074] When the current loop of the current controller 13 drives the motor current, the motor current is required to generate the torque current TrqRef. The internal permanent magnet (IPM) controller 31 is configured to separate the torque current TrqRef into IdRef and IqRef based on the difference between Ld and Lq for an internal mounted magnetic motor with variable reluctance. For a surface mounted magnetic (SMM) motor with a constant air gap, IqRef is equal to TrqRef, and IdRef is equal to 0. IqRef is the current command on the q axis (i.e., the reference current value). In other words, IqRef is the value of the target current for the Iq current component. Similarly, IdRef is the value of the target current for the Id current component (i.e., the reference current value). The IPM controller 31 also receives the field weakening current IdFwk, which is limited by block 45 based on FwkCurRatio. The flux weakening current IdFwk is calculated by the field weakening block 44 based on FwkVoltLvl (which indicates the field weakening level) and Vdq (which is the square root of Vd and Vq). FwkVoltLvl sets the field weakening level. For both surface magnet motors (SMM) and interior permanent magnets (IPM), the field weakening current IdFwk is added to IdRef in the IPM controller 31.

[0075] The current Iq loop PI compensator 34 acts on the error ErrIq between IqRef and Iq. This current Iq loop PI compensator 34 is also referred to as an Iq controller 34. The integral term forces the steady-state error to zero, while the proportional term improves high-frequency response. The PI compensator gains KP and KI are adjusted based on the motor and load characteristics to meet the target dynamic performance. The limit function block 36 applies one or more limit functions to the output of the PI compensator 34 to prevent integral windup and maintain the inverter output voltage based on VdqLim (the limit on Vdq).

[0076] Similarly, the error ErrId between IdRef and Id is acted upon by the current Id loop PI compensator 35, also referred to as an Id controller 35. The PI compensator gains KP and KI are adjusted depending on the motor and load characteristics to meet the target dynamic performance, but are generally the same as those of the current Iq loop PI 34. A limit function block 37 applies one or more limit functions to the output of the PI compensator 35 to prevent integral windup and maintain the inverter output voltage based on VdqLim.

[0077] The forward vector rotation unit 38 applies forward vector rotation to the current loop output voltages Vd and Vq and converts them into two-phase AC voltage components Vα and Vβ based on the rotor angle calculated by the flux estimator and PLL unit 43. The space vector pulse width modulator 39 receives the two-phase AC voltage components Vα and Vβ and generates inverter switching signals (i.e., PWM control signals for the six paths output from the motor controller 6) based on the Vα and Vβ voltage inputs and SVPWM. The gate driver 7 then turns the corresponding power transistors 3 on and off based on the PWM control signals.

[0078] The current loop of current controller 13 calculates the inverter voltage to drive the motor current required to generate the desired torque. Phase current reconstruction circuit 40 uses single-shunt reconstruction to reconstruct each of the phase currents Iu, Iv, and Iw for each corresponding phase U, V, and W. Specifically, phase current reconstruction circuit 40 measures the DC link current in the shunt resistor during the active vector of the PWM cycle. In each PWM cycle, there are two different active vectors, and the DC link current in each active vector represents the current in one motor phase. Because the sum of all three winding currents is zero under balanced conditions, the third phase current value can be calculated.

[0079] Field-oriented control (FOC) applies an α-β transformation to the three-phase currents using Clarke transformation at a Clarke transformation unit 41 to derive an α current Iα and a β current Iβ. FOC also uses vector rotation (i.e., coordinate rotation) at a vector rotation unit 42 to transform the motor winding currents using the α and β currents Iα and Iβ into two quasi-DC current components: an Id current component that strengthens or weakens the rotor magnetic field, and an Iq current component that generates motor torque.

[0080] Two error generators (e.g., subtractors) 32 and 33 generate error values ​​ErrIq and ErrId, respectively. Specifically, error generator 32 receives reference current value IqRef as a set value (SP) from IPM control block 31 and Iq current value as a real measurement value (PV) from vector rotation unit 42, and generates error value ErrIq. Similarly, error generator 33 receives reference current value IdRef (i.e., a reference current value on the d-axis) as a set value (SP) from IPM control block 31 and Id current value as a real measurement value (PV) from vector rotation unit 42, and generates error value ErrId.

[0081] Typically, the torque reference current from the speed controller is separated into Iqref and Idref by the IPM control block 31 based on the difference in the motor inductances Ld and Lq. Normally, for an SMM motor, IdRef is zero; or for an IPM motor, IdRef is a negative value scaled with the torque current TrqRef. However, above a certain speed (called the base speed), the inverter output voltage becomes limited by the DC bus voltage. In this case, the field weakening controller 44 generates a negative Id, which is added to the Id separated from the torque reference current to counteract the rotor magnetic field that reduces the winding electromotive force (EMF). This enables operation at higher speeds but lower torque output. The field weakening block 44 is used to adjust the Id current to keep the motor voltage within the bus voltage limit.

[0082] The rotor magnet position estimator includes a flux estimator and a PLL 43. The flux estimator and flux PLL operate to detect the rotor position and measure the motor speed of the running motor. The flux is calculated based on the feedback current (i.e., using the α and β currents Iα and Iβ), the estimated voltages Vα and Vβ (based on the DC bus feedback voltage and the modulation index), and the motor parameters (inductance and resistance). The output of the flux estimator represents the rotor flux in the α-β two-phase (stationary orthogonal coordinate system, with the u phase aligned with the α phase).

[0083] The angle and frequency phase-locked loop (PLL) of the flux estimator and PLL 43 estimates the flux angle (i.e., the estimated rotor angle) and motor speed based on the rotor flux vector in the α-β component. The PLL's vector rotation calculates the error between the rotor flux angle and the estimated angle. The PLL's PI compensator and integrator in the closed-loop path force the angle and frequency estimates to track the rotor flux angle and frequency. The motor speed is derived from the rotor frequency based on the number of rotor poles.

[0084] When driving an Interior Permanent Magnet (IPM) motor, the rotor salient poles generate a reluctance torque component to increase the torque generated by the rotor magnets. When driving a Surface Magnet Motor (SMM), the salient poles are zero (Ld = Lq), and for maximum efficiency, Id is set to zero. In the case of an IPM motor with negative salient poles (Ld < Lq), a negative Id will generate a positive reluctance torque. The most efficient operating point is when the total torque is maximized for a given current magnitude. The most efficient operating points of the Surface Magnet Motor (SMM) and Interior Permanent Magnet (IPM) are calculated by the IPM control block 31.

[0085] It should be understood that the illustrated speed constant controller 12 and current controller 13 only illustrate one example configuration and are not limited thereto. For example, generally, the speed constant controller 12 is configured with a speed control loop that outputs a torque current TrqRef based on the target speed TargetSpeed. Additionally, the current controller 13 is configured to calculate voltage information and current information for driving the motor based on the torque current TrqRef output from the speed constant controller 12. Specifically, the current controller 13 determines the stator q-axis voltage Vq and d-axis voltage Vd, as well as the stator q-axis current Iq and d-axis current Id. The voltage and current information Vd, Vq, Iq, and Id are provided to the power constant controller 11, and specifically to the power feedback estimator 51 of the power constant control loop 11.

[0086] The power feedback estimator 51 receives the voltage and current information Vd, Vq, Iq, and Id from the current control loop 13 and calculates the feedback power of the motor M. Specifically, the Vd, Vq, Id, Iq inputs of block 51 are supplied by blocks 42, 36, and 37 respectively. As pointed out above, the motor power is also the output power of the inverter 1. Therefore, the feedback power calculated by the power feedback estimator 51 is the motor power, or Figure 1A the output power of the inverter 1 shown in

[0087] The feedback power Pfb is calculated by the following DQ coordinate equation, namely Equation 3:

[0088]

[0089] Here, Equation 3 is based on the principle of the normal coordinate formula represented by Equation 4 through equal amplitude transformation:

[0090] Power = u a i a + u b i b + u[[ID=2​​​​​​​c It represents the instantaneous value of the three-phase voltage input to the motor, and i a ,i b ,i c Indicates the instantaneous value of the three-phase current input to the motor.

[0091] The first power scaler, i.e., power normalization block 52, scales the feedback power Pfb to derive a scaled (normalized) feedback power value Pscfb. Thus, the first power scaler 52 normalizes the feedback power Pfb, and the output of the power scaler, power normalization block 52 is represented by the following equation 5:

[0092]

[0093] The scaled (normalized) feedback power value Pscfb is then provided to a second scaler, i.e., a power adjustment block 53, which converges (scales) the scaled feedback power value Pscfb (i.e., output power) to the input power Inputpower based on the adjustment parameter. The input power value Inputpower is then provided to an error generator (e.g., a subtractor) 54. The error generator 54 receives the target power value (TargetPower) as a reference value and the input power value Inputpower from the second scaler 54, and thereby generates a power error value ErrPower. The power error value ErrPower is the deviation or difference between the target power and the actual (estimated) input power. In other words, if the target power and the actual (estimated) input power Inputpower are equal, the power error value ErrPower is zero; if the target power and the actual (estimated) input power Inputpower are not equal, the power error value ErrPower is not zero, and therefore represents the difference between the two.

[0094] The error generator 54 provides the power error value ErrPower to the power control loop PI controller 55, and the PI controller 55 generates a target speed (TargetSpeed) based on the power error value ErrPower. The target power TargetPower comes from the external signal generator 16, which is configured to generate an external digital signal or analog signal 16s (UART, VSP, frequency, and duty cycle) that provides the target power TargetPower. The external signal generators 15 and 16 can be separate devices or can be combined into a single device.

[0095] The target speed (TargetSpeed) output from the power control loop PI controller 55 is limited by a limit function block 56. For example, when the target speed (TargetSpeed) exceeds a threshold value MaxSpeedLim (=MaxSpeed), the target speed will be limited to MaxSpeedLim (maximum speed limit of the motor), where MaxSpeed ​​is the maximum speed of the motor.

[0096] Switch 61 is used to implement a fast start operation using the constant speed control mode before the constant power control mode. Specifically, the motor controller 6 will be set in the constant speed control mode to perform a fast start operation of the motor, and then after one or more motor starting conditions have been met, the motor controller 6 will switch to the constant power control mode. The timing and relationship between these two control modes are described in Figure 5 is further illustrated in FIG.

[0097] In the first step of the fast start (i.e., constant speed control mode), the motor speed MotorSpeed ​​of the motor, as monitored by the fast start logic module 58, is less than 5%*MaxSpeed. In addition, the start flag output from the fast start logic module 58 has been initialized to 0 in response to the motor stop state (e.g., Figure 1A (The controller 6 in FIG40 receives a motor stop command or does not receive a start command after power-on.) This means that before the controller 6 enters the motor run state, the start flag is set to 0, and after the controller 6 enters the run state while the motor speed MotorSpeed ​​is less than 5%*MaxSpeed, the start flag remains at 0. Therefore, the fast start logic module 58 receives the measured motor speed MotorSpeed ​​from block 43, compares the motor speed MotorSpeed ​​with a mode threshold (e.g., 5%*MaxSpeed), and sets the value of the start flag based on the comparison result. The mode threshold represents the switching point between the two control modes and can be configurable based on the corresponding application.

[0098] The start flag output from the fast start logic module 58 is a control signal for the switch 61, which is used to switchably control its on / off state. As a result of the start flag being set to 0, the target speed of the speed controller 12 is connected to the signal generation block 57 (10%*MaxSpeed), which sets the target speed TargetSpeed ​​of the TargetSpeed ​​signal path to 10%*MaxSpeed. It will be understood that the fraction or percentage of the MaxSpeed ​​value applied by the signal generation block 57 is configurable based on the corresponding application.

[0099] The TargetSpeed ​​signal path may include a control mode switch 61 for fast start control and / or may include a fail-safe switch 62 for fail-safe control. In other words, fast start control and fail-safe control may be implemented independently of each other, or may be implemented in combination as shown. If fail-safe control is not implemented, switch 62, block 59, and block 60 may be removed, and the output of switch 61 will be coupled to switch 63. If fast start control is not implemented, switch 61, block 57, and block 58 may be removed, and switch 62 will be coupled to block 56 when the fail-safe flag = 0. Therefore, the TargetSpeed ​​signal path can change according to the switch state of these switches to provide TargetSpeed ​​to block 21. The TargetSpeed ​​signal path may also include blocks 57, 58, and 59, each of which generates a value for the target speed TargetSpeed ​​provided to block 21.

[0100] Typically, the fail-safe function will only be run after the fast startup has completed. During the fast startup process, the fail-safe function is not enabled, so the fail-safe flag = 0, and switch 62 is connected to switch 61. After the fast startup process, the startup flag output from block 58 is set to 1, then switch 61 is connected to block 56, and the fail-safe function is enabled. Switch 62 will be connected to switch 61 or block 59 depending on the fail-safe state.

[0101] In the first step, when the start flag is 0, the power loop integral is initialized by the fast start logic module 58. Then, the PI controller 55 is initialized to the normal speed of the target power, which is the motor speed corresponding to the target power of the motor. This means that in the following PI 55 controller expression, KI∫Δdt is initialized to the normal speed of the target power.

[0102] PI output = KPΔ + KI∫Δdt, Equation 6,

[0103] In the second step of the fast start (i.e., constant power control mode), the motor speed, as monitored by the fast start logic module 58, is equal to or greater than 5%*MaxSpeed. As a result of meeting this threshold, the start flag output from the fast start logic module 58 is set to 1. In response to the start flag being set to 1, the target speed of the speed controller 12 is connected to the block 56, which is the output of the power control loop. As a result, the control mode of the motor controller 6 is changed from the constant speed control mode to the constant power control mode.

[0104] Figure 3BFIG3 is a schematic block diagram of fast startup logic module 58 according to FIG3A . Fast startup logic module 58 includes a threshold generator 58a, a comparator 58b, and a motor state detector 58c. Threshold generator 58a sets the mode threshold used by comparator 58b. Motor state detector 58c detects the state of the motor, and more specifically, detects when the motor is stopped. When the motor is stopped, motor state detector 58c sets the start flag to 0, which also initializes PI controller 55.

[0105] Therefore, first, the start flag is set to 0 by the motor state detector 58c, so that when the controller 6 enters the running state, the start flag has been initialized to 0. As a result, the switch 61 is connected to the block 57 that implements constant speed control, and the integral of the power loop PI 55 is initialized to the normal speed of the target power in this process. For example, the mode threshold can be set based on a preset fraction or percentage of the maximum speed of the motor MaxSpeed. The comparator 58b receives the mode threshold from the threshold generator 58a and the measured motor speed MotorSpeed ​​from the block 43 and performs a comparison. If the measured motor speed MotorSpeed ​​is equal to or greater than the mode threshold, the comparator 58b sets the start flag to 1. The state of the switch 61 is controlled by the start flag generated by the fast start logic module 58.

[0106] The power calculation method used by power controller 11 is affected only by the accuracy of current sampling derived from stator q-axis current Iq and d-axis current Id, and the accuracy of stator q-axis voltage Vq and d-axis voltage Vd output from PI controllers 34 and 35. As a result, this method works well over the entire motor speed range, including the flux weakening region. However, it does not work well under overmodulation conditions.

[0107] Note that the second scaler 53 performs input power adjustment to derive the measured input power from the scaled feedback power Pscfb (i.e., the scaled output power). As shown in FIG3A , to control the input power of inverter 1 for battery protection, an adjustment parameter is set on the feedback power signal path. This adjustment parameter is set according to the following procedure.

[0108] First, the adjustment value at the second scaler 53 is set to 1, the target power is varied at multiple values ​​from low power to maximum power, and for each value of the varied target power, the input power value output by the second scaler 53 is recorded in the memory.

[0109] Second, the ratio between the input power and the target power is calculated based on the recorded value. The determined ratio is set as the adjustment parameter (i.e., scaler value) for the second scaler 53. Therefore, the adjustment parameter is set so that the scaled output power from the first scaler 52 converges to the input power. In other words, the scaled output power is converted into the estimated input power Inputpower.

[0110] After the above steps, the input power of the inverter can be matched to the target power using the error generator 54 and the PI controller 55. The output of the PI controller 45 is the target speed (TargetSpeed) provided by the power controller 11.

[0111] The fast start function will now be described using the motor control algorithm 300 .

[0112] Test the normal motor speed (rpm / s) at a number of target power points. These target power points are set at equal intervals, from small to large. For example, the target power points can be percentages set in 10% increments from 0% to 100%, where 100% represents the maximum target power for the motor. Then, perform curve fitting to construct a curve for the target power and normal motor speed. Figure 4 The graph shows a fitting curve (ie, a normal speed fitting curve) in which the normal motor speed is fitted to the target power.

[0113] The equation for the fitted curve is set forth in Equation 7 below:

[0114] Normal speed = A*target power^2 + B*target power + C Equation 7

[0115] (NormalSpeed=A*TargetPower^2+B*TargetPower+C)

[0116] Where A, B, and C are the fitting parameters used to fit the curve.

[0117] Figure 5FIG3 is a diagram illustrating a motor rapid startup process according to one or more embodiments, compared to a conventional constant power startup process. According to the startup process implemented using the motor control algorithm 300, the motor M is first started using constant speed control. That is, the motor controller 6 is initially set to constant speed control mode upon startup (i.e., when the motor power switch is turned on). The target speed TargetSpeed ​​is set to 10% of the maximum speed MaxSpeed ​​by the signal generator 57. When the motor speed MotorSpeed ​​determined by the flux estimator and PLL unit 43 reaches a predetermined percentage of the maximum speed MaxSpeed, the rapid startup logic module sets the startup flag to 1, and the switch 61 responds by coupling to the block 56 to implement a transition from constant speed control to constant power control. The predetermined percentage is set to a percentage or amount greater than zero but less than the rapid startup target speed TargetSpeed ​​(e.g., 10% of the maximum speed MaxSpeed) in the first step of the rapid startup. In this example, the predetermined percentage is set to 5%, but is not limited thereto.

[0118] This predetermined percentage corresponds to a switching threshold or switching point for the motor speed at which the operating mode of the motor controller 6 switches from the constant speed control mode to the constant power control mode. Thus, when the motor speed in this example reaches 5% of the maximum speed, the control mode switches to the constant power control mode. After startup, the control mode will remain in the constant power control mode, or the control mode can be disabled to meet other system requirements during the motor runtime following the startup period. The startup period is defined as the increase from zero motor speed to a normal speed corresponding to the target power.

[0119] In the first step of the quick start process, use Figure 4 The fitting curve shown in FIG initializes the integration of the power controller 55 to the normal speed NormalSpeed ​​at this moment. Here, the normal speed corresponds to the target power TargetPower. Figure 5 A diagram illustrating a motor rapid start process according to one or more embodiments compared to a conventional constant power start process, a normal speed corresponding to a target power_A is normal speed_A.

[0120] While the power control loop is initialized to the normal speed (NormalSpeed), the target speed (TargetSpeed) of the speed control mode will remain at the normal speed. This is because the frequency bandwidth of the power controller 55 is smaller than that of the speed controller 23, and the integral of the power controller 55 is affected by the speed controller 23. Therefore, these characteristics can be used to achieve a quick start of the motor.

[0121] In view of the above, the power constant control is configured to maintain the power consumption at a constant level, which can, for example, maintain the airflow in the fan application, and can be implemented using the currents Iq and Id and the voltages Vd and Vq as its feedback inputs. In addition, the measured output power of the inverter 1 is adjusted (i.e., converted) to the input power of the inverter 1 by the power control loop 11 (e.g., scalers 52 and 53), which provides battery power protection. In addition, during motor startup, before switching to the power constant control mode, the speed constant control mode can be used first to achieve faster startup. By checking the motor speed when the inlet of the fan is blocked, it can be seen which mode the motor controller 6 is in. When the motor speed changes and the inlet of the fan is blocked, the motor controller 6 is in power constant control. When the motor speed does not change and the inlet of the fan is blocked, the motor controller 6 is in speed constant control mode.

[0122] 3A , the power controller 11 may further include a fail-safe switch 62 controlled by a fail-safe logic module 60. The switch 62 is used to implement a fail-safe function while the motor controller 6 is in the constant power control mode. The fail-safe logic module 60 is configured to receive the measured motor speed MotorSpeed ​​from the block 43 and perform a comparison thereon.

[0123] The fail-safe flag is initialized to 0, so if the motor is operating in the constant power control mode and the measured motor speed MotorSpeed ​​is less than the fault speed threshold VacFaultSpeed, the fail-safe logic module 60 maintains the fail-safe flag at 0 and thus controls the fail-safe switch 62 to be connected to the switch 61, which is connected to the block 56 in the constant power control mode. As a result, the motor controller 6 continues to operate in the constant power control mode.

[0124] If the motor is operating in the constant power control mode and the measured motor speed (MotorSpeed) is equal to or greater than the fault speed threshold (VacFaultSpeed), the fail-safe logic module 60 sets the fail-safe flag to 1 and, accordingly, controls the connection of the fail-safe switch 62 to the signal generator block 59. The signal generator block 59 sets the target speed (TargetSpeed) to the minimum power speed (MinPowerSpeed). As a result, the target speed provided to the block 21 is set to the MinPowerSpeed ​​value, and the control mode of the motor controller 6 switches to the constant speed control mode in response to entering the fail-safe state. That is, by coupling the switch 61 to the signal generator 59, the motor controller 6 switches out of the constant power control mode and into the constant speed control mode.

[0125] Fail-safe logic module 60, and therefore motor controller 6, remains in the fail-safe state until certain conditions are met. For example, a safe operating condition is detected, in response to which fail-safe logic module 60 reconnects switch 62 to switch 61 by setting the fail-safe flag to 0. Alternatively, an unsafe condition continues to exist, and fail-safe logic module 60 then shuts down the motor.

[0126] In the fail-safe state, fail-safe logic module 60 continues to monitor measured motor speed MotorSpeed ​​and, based on an evaluation of measured motor speed MotorSpeed, switchably couples fail-safe switch 62 to switch 61 (which is set in its position coupled to block 56 in constant power control mode and represents a fail-safe constant power control mode) or to signal generator 59 (representing a fail-safe constant speed control mode). Fault speed threshold VacFaultSpeed ​​can be set, for example, to 1.08*NormalSpeed. Minimum power speed MinPowerSpeed ​​can be set, for example, to 0.7*NormalSpeed. However, these thresholds are configurable based on the application.

[0127] In the fail-safe state, when fail-safe switch 62 is coupled to signal generator 59 (i.e., fail-safe flag = 1), the measured motor speed MotorSpeed ​​should decrease. If the measured motor speed MotorSpeed ​​reaches (i.e., decreases to) the minimum power speed threshold MinPowerSpeed, the fail-safe logic module 60 sets the fail-safe flag to 0 and connects fail-safe switch 62 to block 56, which is the output of the power control loop. As a result, the mode of motor controller 6 changes from the fail-safe constant speed control mode to the fail-safe constant power control mode.

[0128] This process can be repeated one or more times. For example, while still in the fail-safe state, the measured motor speed MotorSpeed ​​can begin to increase again toward the fault speed threshold VacFaultSpeed. If the measured motor speed MotorSpeed ​​reaches or exceeds the fault speed threshold VacFaultSpeed, the fail-safe logic module 60 enters the fail-safe constant speed control mode by setting the fail-safe flag to 1, which causes the fail-safe switch 62 to connect to the signal generator 59.

[0129] Figure 3C3A is a schematic block diagram of a fail-safe logic module 60. The fail-safe logic module 60 includes a first threshold generator 60a, a second threshold generator 60b, a first comparator 60c, and a second comparator 60d. The first threshold generator 60a sets a fault speed threshold VacFaultSpeed ​​used by the first comparator 60c. For example, the fault speed threshold VacFaultSpeed ​​can be set to be greater than the normal motor speed and can be a preset fraction or percentage of the normal motor speed.

[0130] The second threshold generator 60b sets a minimum power speed threshold MinPowerSpeed ​​used by the second comparator 60d. The minimum power speed threshold MinPowerSpeed ​​can be set to be less than the motor normal speed, and can be a preset fraction or percentage based on the motor normal speed.

[0131] Comparators 60 c and 60 d both receive their respective thresholds and the motor speed MotorSpeed ​​measured from block 43 and perform corresponding comparisons. If the measured motor speed MotorSpeed ​​is equal to or greater than the fault speed threshold VacFaultSpeed, comparator 60 c sets the fail-safe flag to 1, causing the motor controller 6 to enter the fail-safe constant speed control mode and causing the fail-safe switch 62 to be coupled to the signal generator 59.

[0132] If the measured motor speed MotorSpeed ​​is equal to or less than the minimum power speed threshold MinPowerSpeed, the comparator 60d sets the fail-safe flag to 0, causing the motor controller 6 to enter the fail-safe power constant control mode and causing the fail-safe switch 62 to be coupled to the block 56.

[0133] As will be described in more detail below, the fail-safe condition enables the vacuum cleaner or other suction appliance to automatically (ie, without user intervention) remove inlet obstructions during runtime of the motor while in the constant power control mode.

[0134] Figure 6is a diagram illustrating the motor speed and input power of the inverter 1 according to the fail-safe state of the motor controller 6 according to one or more embodiments. As noted above, when in the power constant control mode (i.e., switch 61 is coupled to block 56), the motor controller 6 can repeatedly switch between the fail-safe speed constant control mode (i.e., switch 62 is coupled to block 59) and the fail-safe power constant control mode (i.e., switch 62 is coupled to block 56). As described above, the fail-safe logic module 60 monitors the measured motor speed MotorSpeed ​​and controls the switch 62 accordingly.

[0135] While in constant power control mode, the motor speed is maintained at NormalSpeed ​​by the power control loop 11 based on the target power TargetPower. In the event of an inlet blockage, the motor speed will automatically increase. If the motor speed increases to the fault speed threshold VacFaultSpeed, the fail-safe logic module 60 will enter a fail-safe state and couple switch 62 to the signal generator 59 to reduce the motor speed, which helps prevent temperature increases. If the motor speed decreases to the minimum power speed threshold MinPowerSpeed, the fail-safe logic module 60 will couple switch 62 back to the limit function block 56 to allow the motor speed to increase based on the target speed TargetSpeed ​​output by the PI controller 55 and the limit function block 56. If the inlet blockage still exists, the motor speed will automatically increase back to the fault speed threshold VacFaultSpeed, causing the process to repeat. If the inlet obstruction is cleared (i.e., removed), the motor speed will likely not increase back to the fault speed threshold VacFaultSpeed, and the fail-safe logic module 60 may decide to exit the fail-safe state and resume normal operation in the constant power control mode. If the motor speed reaches the fault speed threshold VacFaultSpeed ​​a threshold number of times (e.g., 5 times) consecutively while in the fail-safe state, the fail-safe logic module 60 may disable the motor function and stop the motor.

[0136] Switching between the fail-safe constant speed control mode and the fail-safe constant power control mode allows the motor speed to change rapidly. Figure 7 The input power of inverter 1 can be seen in the dramatic changes in the vacuuming force during this process. This change in airflow (i.e., suction) applies to debris blocking the inlet, with the goal of releasing or drawing the debris in through the vacuum created by the varying force. If this process fails to remove the obstruction, the motor is stopped after several intervals to allow manual removal and prevent damage to the motor and / or circuit boards.

[0137] Figure 7 7 is a flow chart of a fail-safe logic flow implemented by the fail-safe logic module 60 according to one or more embodiments. The fail-safe logic flow 700 includes a normal operating state 701, a blocking and speed-up state 702, a blocking and speed-down state 703, and a stop state 704, all of which operate in a main power constant control mode of the motor controller 6. During the main power constant control mode, the switch 61 is coupled to the limit function block 56.

[0138] With switch 61 coupled to limit function block 56 and switch 62 coupled to switch 61, motor controller 6 operates in normal operating state 701 until the inlet is blocked. When the inlet is blocked, normal operating state 701 switches to blocked and increased speed state 702. In response to the measured motor speed increasing from normal speed, the blocked inlet is detected by fail-safe logic module 60. For example, fail-safe logic module 60 may compare the measured motor speed with a predetermined threshold (e.g., 1.01*NormalSpeed) to detect a blocked inlet.

[0139] If the motor is in the Blocked and Accelerated State 702 for a predetermined time interval (e.g., six seconds) via the fail-safe logic module 60 and the motor speed does not reach the VacFaultSpeed, the fail-safe logic module 60 returns to the Normal Operation State 701. This may indicate that the inlet blockage is partial or temporary and poses no risk to the motor or circuit board. In the Blocked and Accelerated State 702, the control mode remains the primary constant power control, and the target speed is equal to the output of the PI controller 55 and the limit function block 56. The fail-safe state has not yet been triggered.

[0140] Conversely, if the motor speed reaches VacfaultSpeed ​​in the Blocking and Speeding Up state 702, the fail-safe logic module 60 switches to the Blocking and Speeding Down state 703, and the VacFault (fault count) count value is incremented by 1. By entering the Blocking and Speeding Down state 703, the fail-safe logic module 60 has triggered the fail-safe state. Here, the target speed is set to MinPowerSpeed, and the fail-safe constant speed control mode is implemented as a sub-state. When the motor speed decreases to MinPowerSpeed, the fail-safe logic module 60 switches again to the Blocking and Speeding Up state 702 and returns to the constant power control mode.

[0141] The blocking and speed-up state 702 is repeated, and the fail-safe state can be exited by satisfying the criteria for switching to the normal operation state 701, or the fail-safe state can be maintained by switching to the blocking and speed-down state 703 after the criteria are satisfied. In the latter case, the blocking and speed-down state 703 is repeated.

[0142] Each time the fail-safe logic module 60 switches to the Block and Reduce Speed ​​state 703, the VacFault count value stored in the counter of the fail-safe logic module 60 is incremented by 1 and compared to a count threshold (e.g., Fault value = 5). If the VacFault count value equals the count threshold, the fail-safe logic module 60 switches to the Stop state 704 and stops the motor by setting VacFaultFlag (fault count flag) = 1. If the VacFault count value is less than the count threshold, the fail-safe logic module 60 monitors the motor speed by comparing it to MinPowerSpeed ​​and triggers the Increase Speed ​​state 702 if the motor speed is equal to or less than MinPowerSpeed, thereby increasing the motor speed.

[0143] The fail-safe logic module 60 provides the following advantages. The fail-safe state extends the life of the permanent magnet synchronous motor and prevents burnout. The fail-safe state is implemented at a low cost using sensorless field-oriented control (FOC). Constant power control maintains airflow when the inlet is not completely blocked. Repeatedly and rapidly decreasing and increasing the motor speed automatically clears debris.

[0144] Although various embodiments have been described, it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the present disclosure. Accordingly, the present invention is not to be limited except in accordance with the appended claims and their equivalents. With respect to the various functions performed by the components or structures (accessories, devices, circuits, systems, etc.) described above, unless otherwise indicated, terms used to describe such components (including references to "devices") are intended to correspond to any component or structure that performs the specified function of the described component (i.e., is functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs the functions described herein in the exemplary implementations of the invention.

[0145] Furthermore, the following claims are hereby incorporated into the detailed description, where each claim can stand on its own as a separate example embodiment. Although each claim can stand on its own as a separate example embodiment, it should be noted that—although a dependent claim may refer to a specific combination with one or more other claims in a claim—other example embodiments can also include combinations of the subject matter of a dependent claim with each other dependent or independent claim. Unless it is stated that a specific combination is not intended, such combinations are contemplated herein. Furthermore, it is intended that features of a claim be included in any other independent claim, even if that claim is not directly dependent on that independent claim.

[0146] It is also noted that methods disclosed in the specification or claims may be implemented by a device having means for performing each of the corresponding acts of these methods.

[0147] Furthermore, it should be understood that the disclosure of multiple actions or functions disclosed in the specification or claims may not be interpreted as being in a particular order. Thus, the disclosure of multiple actions or functions will not restrict them to a particular order unless, for technical reasons, these actions or functions are not interchangeable. Furthermore, in some embodiments, a single action may include or be divided into multiple sub-actions. Unless expressly excluded, such sub-actions may be included and be part of the disclosure of the single action.

[0148] Depending on certain implementation requirements, the embodiments provided herein can be implemented in hardware or in software. Implementation can be performed using a digital storage medium (e.g., a floppy disk, DVD, Blu-ray, CD, RAM, ROM, PROM, PROM, EPROM, EEPROM, or FLASH memory) having electronically readable control signals stored thereon, which cooperates (or can cooperate with) a programmable computer system to perform the corresponding method. Therefore, the digital storage medium can be computer-readable.

[0149] Instructions can be executed by one or more processors, such as one or more central processing units (CPUs), digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Thus, as used herein, the term "processor" refers to any of the foregoing structures or any other structure suitable for implementing the techniques described herein. Additionally, in some aspects, the functionality described herein can be provided within dedicated hardware and / or software modules. Likewise, the technology can be fully implemented in one or more circuits or logic elements.

[0150] Thus, the techniques described in this disclosure may be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, various aspects of the described techniques may be implemented within one or more processors, including one or more microprocessors, DSPs, ASICs, or any other equivalent integrated or discrete logic circuitry, as well as any combination of these components.

[0151] The control unit including the hardware may also perform one or more of the techniques described in this disclosure. Such hardware, software, and firmware may be implemented within the same device or within separate devices to support the various techniques described in this disclosure. The software may be stored on a non-transitory computer-readable medium such that the non-transitory computer-readable medium includes a program code or program algorithm stored thereon that, when executed, causes the computer program to perform the steps of the method.

[0152] Although various exemplary embodiments have been disclosed, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention, which will achieve some of the advantages of the concepts disclosed herein. It will be apparent to those skilled in the art that other components performing the same functions may be appropriately substituted. It will be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the invention. It should be noted that features explained with reference to a particular figure may be combined with features of other figures, even those in those figures not expressly mentioned. Such modifications to the general inventive concept are intended to be covered by the appended claims and their legal equivalents.

Claims

1. A motor controller configured to drive a permanent magnet synchronous motor (PMSM) using sensorless field oriented control (FOC), the motor controller comprising: a current controller configured to generate a control signal for driving the PMSM, wherein the current controller is configured to measure voltage information of the PMSM and current information of the PMSM; a power constant controller configured to receive the voltage information and the current information, and generate a first target speed based on a target power of the PMSM and based on the voltage information and the current information; a first signal generator configured to generate a second target speed; a speed constant controller coupled between the power constant controller and the current controller, wherein the speed constant controller is configured to switchably receive the first target speed and the second target speed and adjust the motor speed of the PMSM based on the received first target speed or the received second target speed; a first switch configured to switchably couple the constant speed controller to the constant power controller in a first switching state to receive the first target speed, or to couple the constant speed controller to the first signal generator in a second switching state to receive the second target speed; as well as a first switch controller configured to control a switching state of the first switch, The power constant controller comprises: a power feedback estimator configured to receive the voltage information and the current information from the current controller and calculate the feedback power of the PMSM based on the voltage information and the current information, a first scaler configured to receive the feedback power from the power feedback estimator and convert the feedback power into a scaled feedback power, The power constant controller is configured to generate the first target speed based on the target power and the scaled feedback power.

2. The motor controller according to claim 1, wherein: The speed constant controller is configured to generate a first torque current based on the first target speed and to generate a second torque current based on the second target speed, wherein the first torque current corresponds to a first motor torque applied to the PMSM to achieve the first target speed, and the second torque current corresponds to a second motor torque applied to the PMSM to achieve the second target speed, and The current controller is configured to generate the control signal based on the first torque current or the second torque current.

3. The motor controller according to claim 1 , further comprising: a second signal generator configured to generate a third target speed; a second switch configured to switchably couple the constant speed controller to the first switch in a first switch state to receive the first target speed or the second target speed, or to couple the constant speed controller to the second signal generator in a second switch state to receive the third target speed; as well as A second switch controller is configured to control a switching state of the second switch, The speed constant controller is coupled to the second switch and is configured to receive the first target speed, the second target speed, or the third target speed based on the switch state of the first switch and the switch state of the second switch.

4. The motor controller according to claim 1, wherein: The voltage information includes a first motor voltage component corresponding to a q-axis of a DQ coordinate system and a second motor voltage component corresponding to a d-axis of the DQ coordinate system, and The current information includes a first current component corresponding to the q-axis of the DQ coordinate system and a second motor current component corresponding to the d-axis of the DQ coordinate system. 5 . The motor controller according to claim 1 , wherein the first scaler converts the feedback power into the scaled feedback power by normalizing the feedback power.

6. The motor controller according to claim 1, wherein the power constant controller comprises: a power adjuster configured to receive the scaled feedback power and convert the scaled feedback power into an estimated input power, The power constant controller is configured to generate the first target speed based on the target power and the estimated input power.

7. The motor controller of claim 6, wherein the estimated input power represents input power of a power inverter coupled to an output of the current controller.

8. The motor controller according to claim 6, wherein the power constant controller comprises: an error generator configured to receive the target power and the estimated input power and compare the target power and the estimated input power to generate an error signal, The power constant controller is configured to generate the first target speed based on the error signal.

9. The motor controller according to claim 8, wherein the power constant controller comprises: A proportional-integral (PI) controller is configured to receive the error signal and generate the first target speed based on the error signal.

10. The motor controller according to claim 1, wherein: The current controller is configured to measure the motor speed of the PMSM, and The first switch controller is configured to receive the measured motor speed and control the switching state of the first switch based on the measured motor speed.

11. The motor controller according to claim 10, wherein: The first switch controller is configured to compare the measured motor speed with a motor speed threshold, control the first switch to be in the second switching state when the measured motor speed is less than the motor speed threshold, and control the first switch to be in the first switching state when the measured motor speed is equal to or greater than the motor speed threshold. 12 . The motor controller of claim 11 , wherein the second target speed is greater than a first motor speed threshold, and the first target speed is greater than the second target speed.

13. A method for driving a permanent magnet synchronous motor (PMSM) using sensorless field oriented control (FOC), the method comprising: generating, by a current controller, a control signal for driving the PMSM; Measuring voltage information of the PMSM and current information of the PMSM by the current controller; generating, by a power constant controller, a first target speed based on a target power of the PMSM and based on the voltage information and the current information; generating a second target speed by a first signal generator; The first target speed and the second target speed are switchably received by a constant speed controller, the constant speed controller being coupled between the constant power controller and the current controller; adjusting, by the speed constant controller, a motor speed of the PMSM based on the received first target speed or the received second target speed; A first switch is switchably coupled by a first switch to couple the constant speed controller to the constant power controller in a first switching state to receive the first target speed, or to couple the constant speed controller to the first signal generator in a second switching state to receive the second target speed; The first switch controller controls the switching state of the first switch; Calculating, by the power constant controller, the feedback power of the PMSM based on the voltage information and the current information; The power constant controller converts the feedback power into a scaled feedback power; converting the scaled feedback power into an estimated input power by the power constant controller; generating an error signal by the power constant controller by comparing the target power and the estimated input power; as well as The first target speed is generated by the power constant controller based on the error signal.

14. The method according to claim 13, wherein: The voltage information includes a first motor voltage component corresponding to a q-axis of a DQ coordinate system and a second motor voltage component corresponding to a d-axis of the DQ coordinate system, and The current information includes a first current component corresponding to the q-axis of the DQ coordinate system and a second motor current component corresponding to the d-axis of the DQ coordinate system.

15. The method according to claim 13, further comprising: measuring the motor speed of the PMSM by the current controller; as well as The switching state of the first switch is controlled by the first switch controller based on the measured motor speed.

16. The method according to claim 15, further comprising: comparing, by the first switch controller, the measured motor speed to a motor speed threshold; The first switch controller controls the first switch to be in the second switch state under the condition that the measured motor speed is less than the motor speed threshold; as well as The first switch controller controls the first switch to be in the first switching state under the condition that the measured motor speed is equal to or greater than the motor speed threshold. 17 . The method of claim 16 , wherein the second target speed is greater than a first motor speed threshold, and the first target speed is greater than the second target speed.

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