Real-time sensorless motor control drive system

Abstract

The present invention provides a real-time sensorless motor control and drive system. The control and drive system mainly includes a three-phase inverter module, a back-electromotive force detection module, an angle offset module, a switching module, and a low-voltage to high-voltage drive module. The back-electromotive force detection can be applied to a back-electromotive force type motor with a switching point to detect the motor rotation position, which is then transmitted to an angle lag offset circuit to obtain the reversing point required by the drive circuit. At the same time, the frequency is converted into a voltage signal to represent the speed, synchronously reflecting the current motor rotation speed for motor speed control.

Description

Technical Field

[0001] The present invention relates to a real-time sensorless motor control drive system, and more specifically, to a control system that does not require a position sensor or speed sensing device, nor does it use a microprocessor (MCU) for algorithm calculations or computer software monitoring for interrupt calculations, but instead relies on real-time circuit calculations to achieve sensorless motor drive. Background Art

[0002] Generally, brushless DC motors (three-phase BLDC motors, PMSM motors, or PMAC motors) have a simple structure and high efficiency and are widely used in industry. Typically, a three-phase motor uses an armature formed by applying current to a coil as the motor stator, and a permanent magnet formed by repeating north and south poles as the rotor.

[0003] In order for a brushless DC motor to rotate continuously, it must create a continuously rotating magnetic field. Since the stator flux rotates synchronously with the magnetic field of the rotor's permanent magnets, information about the rotor's position may be required. In other words, to create a continuously rotating magnetic field, the current flowing to each phase of the armature coils must be commutated at the appropriate time, requiring the rotor's position to be accurately identified for proper commutation. Commutation, in this context, refers to changing the direction of the current flowing through the motor's stator coils to allow the rotor to rotate.

[0004] For smooth operation of a brushless DC motor, the rotor position and phase current commutation timing must be precisely matched. To achieve this, a device configured to detect the rotor position is required. Typically, rotor position detection sensors such as Hall sensors, resolvers, and encoders are used.

[0005] However, recently, as manufacturing costs increase and driving circuits become complicated, a sensorless method is used that can drive a motor without a sensor for detecting a rotor position.

[0006] A method for driving a brushless DC motor includes extracting back electromotive force (EMF) generated in a stator coil of each phase when the motor rotates, and estimating position information of the rotor and each phase current commutation time by using a zero-crossing point of the back EMF.

[0007] Common methods require additional hardware, such as a microcontroller (MCU) or system-on-a-chip (SoC) with digital logic, resistors, capacitors, diodes, and other complex algorithms, making implementation difficult. Using the MCU or SoC's digital logic resources to perform mathematical calculations to control the motor driver requires the MCU's digital logic to estimate the back EMF position, resulting in slow system actuation and potential delays and inaccuracies.

[0008] Furthermore, using MCU or SoC digital logic to estimate the speed value will also slow down the system, causing delays and inaccuracies. For better application results, high-speed MCU or SoC digital logic is required to achieve better performance, which will also increase costs. Summary of the Invention

[0009] The purpose of the present invention is to provide a control system that does not require position sensors and speed sensing devices, nor does it use a microprocessor (MCU) for algorithm calculations or computer software monitoring for interrupt calculations, but instead uses real-time circuit calculations to achieve sensorless motor drive.

[0010] Another object of the present invention is to provide a real-time sensorless motor control drive system that can achieve drive control at a lower implementation cost without using components such as a microprocessor (MCU) or SoC digital logic and position sensors / speed sensors.

[0011] Another object of the present invention is to provide a real-time sensorless motor control drive system that can be integrated into a single chip. The single-chip solution is convenient for users to directly integrate into a printed circuit board (PCB) application, so that users can easily achieve the purpose of speed control.

[0012] To at least achieve the above-mentioned primary objectives, the present invention is a real-time sensorless motor control drive system for driving a three-phase motor, the control drive system comprising: a three-phase inverter module that converts a DC input voltage into a three-phase AC voltage and supplies the three-phase AC voltage to the three-phase motor; a back electromotive force detection module that detects the center point of the back electromotive force switching from the output terminal of the three-phase inverter and generates a frequency signal with a fixed period, and the frequency signal is regularly synchronized with a frequency three times the back electromotive force frequency of the three-phase motor, thereby obtaining the switching point positions of six back electromotive forces of the motor in multiples of 60 degrees; an angle The degree shift module shifts the frequency signal by 30 degrees, generating short pulse signals that offset the six back-EMF switching points by 30 degrees. Each short pulse signal has a 60-degree difference in motor rotation angle. The switching module uses the short pulse signal as a time switching signal, switching every 60 degrees. After six switching cycles, this six-step switching sequence is repeated for a total of 360 degrees, completing the six-step square wave commutation. The low-voltage to high-voltage drive module performs pulse width modulation (PWM) after the six-step square wave commutation, and accordingly outputs the signals required to control the switching components of the three-phase inverter module, thereby achieving control and drive of the three-phase motor.

[0013] As a preferred embodiment, the control drive system includes a speed control module and a pulse width modulation control module. The speed control module is used to receive external speed instructions and generate a control signal to the pulse width modulation control module, so that the pulse width modulation control module can control the output pulse duty cycle.

[0014] As a preferred embodiment, the control drive system includes a starter motor control module. When the three-phase motor is initially stationary, the starter motor control module uses a variable voltage that gradually increases from small to large to control the frequency signal frequency from slow to fast, and allows the control voltage to gradually increase from small to large to control the short pulse signal frequency of the angle offset module from small to large, thereby providing frequency operation for driving the motor.

[0015] As a preferred embodiment, the control drive system includes a real-time speed estimation module, which uses the aforementioned fixed-cycle frequency signal, and each half-cycle time is the 60-degree rotation angle characteristic of the motor, that is, three times the frequency signal time period is the frequency calculation of one rotation of the motor.

[0016] Preferably, the real-time speed estimation module uses a frequency-to-voltage converter to count the frequency and express the motor speed in terms of voltage.

[0017] Preferably, the back-electromotive force detection module comprises three voltage comparators, each of which determines the difference between the three-phase AC voltage and the center point. The three voltage comparators each determine the switching point between the output terminal and the center point, generating a high- and low-voltage level conversion output. The voltage comparator's downstream stage is connected to a monostable multivibrator to produce three square wave signals with a phase difference of 120 degrees. These three signals are input to an OR gate to be combined into a single signal, which drives a D-type register whose output is inverted and connected to the input, thereby producing a fixed-period frequency signal.

[0018] As a preferred method, the angle offset module uses two sets of constant current charge and discharge circuits to charge and discharge two capacitors to calculate the time. The two sets of constant current charge and discharge circuits are respectively assigned a charge and discharge timing circuit. One set of charge and discharge circuits charges the capacitor in the first half cycle of the frequency signal and discharges the capacitor in the second half cycle. The discharge current is set to twice the charging current, so that the discharge time is half the charging time, which is equivalent to the time it takes for the motor to rotate by 30 degrees.

[0019] As a preferred method, another set of charging and discharging circuits in the angle offset module uses the inverted frequency signal to count, recording the time it takes for another motor to rotate 60 degrees and the 30-degree time offset, so that when the frequency changes from low to high or from high to low, this delay time will be performed.

[0020] As a preferred embodiment, the two sets of charge and discharge output signals of the angle shift module are connected to two comparators and then passed through a bistable multivibrator (SR latch) to generate a frequency signal with a 30-degree offset. The signal is then modulated by a monostable multivibrator to generate a short pulse signal with a 30-degree offset, with each short pulse signal having a 60-degree difference in the motor rotation angle.

[0021] Preferably, the switching module is a 6-bit shift register that pulls the short pulse signal to the frequency input of the 6-bit shift register. Based on the characteristics of the shift register, each frequency cycle will shift, passing the register value to the next level of register, and passing the register value to the next level of register. Switching is performed every 60 degrees, and after six switchings for a total of 360 degrees, this six-step switching sequence is repeated to complete the six-step square wave commutation.

[0022] As a preferred embodiment, the shift register of the switching module pre-sets two register values ​​to high potentials, and the other shift registers to low potentials.

[0023] As a preferred embodiment, the low-voltage to high-voltage (LV to HV) driver module is connected to the shifted and temporarily stored switching components of the corresponding three-phase inverter module through six AND gates, thereby obtaining control signals for the six switching components that control the three-phase motor drive. Due to the AND gate logic function, the AND gate switches can be controlled to function as a pulse width modulation (PWM) function.

[0024] The technical feature of this invention lies in the fact that the pulse waves of the short pulse signal are also spaced 60 degrees apart and lag 30 degrees from the frequency signal, providing a switching signal to the next stage. Here, the back-EMF position is detected by the back-EMF detection module, and a 30-degree lag signal is provided to the power-stage MOS switch for switching. This circuit does not use the MCU or SoC digital logic to calculate the position and lag angle, which will cause delays in switching. It can detect and synthesize the switching signal in real time to drive the power-stage MOS switch. The drive system of this invention can effectively control the motor rotation in real time and achieve sensorless position, current, and speed control.

[0025] The effectiveness of the present invention lies in that it does not require position sensors and speed sensing devices, nor does it use a microprocessor (MCU) for algorithm calculations, or computer software monitoring for interrupt calculations. Real-time circuit calculations can realize the function of sensorless motor driving. It includes back-electromotive force detection, angle offset synthesis, open-loop startup, six-step square wave commutation operation, and current PWM control loop and speed control loop. Among them, back-electromotive force detection can be applied to back-electromotive force type motors with similar switching points such as trapezoidal and sine waves to detect the motor rotation position, and then transmit it to the angle lag offset circuit to obtain the commutation point required by the drive circuit. At the same time, the frequency is converted into a voltage signal to represent the speed, and the current motor rotation speed is synchronously reflected to perform motor speed control. A simple open-loop startup circuit slowly drives the motor to rotate to an appropriate speed steady state and then switches to a closed loop for control. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a block diagram of the real-time sensorless motor control drive system of this application.

[0027] Figure 2 This is a circuit diagram of the back electromotive force detection module of this application.

[0028] Figure 3 This is a circuit diagram of the angle shift module of this application.

[0029] Figure 4 Schematic diagram of the waveforms of SCK and SVCK in this application.

[0030] Figure 5 This is a circuit diagram of the six-step switching module of this application.

[0031] Figure 6 This is a circuit diagram of the low-voltage to high-voltage drive module of this application.

[0032] Figure 7 Schematic diagram of input and output waveforms of SVCK frequency control transformation in this application.

[0033] Figure 8 This is the corresponding diagram of the input and output waveforms of the motor position control loop in this application.

[0034] Figure 9 This is the waveform corresponding to the motor startup in this application.

[0035] Figure 10 This is the waveform corresponding to the real-time speed estimation of this application.

[0036] In the picture:

[0037] 100: Three-phase motor; 200: Control drive system; 210: Three-phase inverter module; 220: Back-EMF detection module; 221: Voltage comparator; 222, 236: Monostable multivibrator; 224: D-type register; 230: Angle shift module; 231, 232: Constant current charge and discharge circuit; 233, 234: Comparator; 235: Bistable multivibrator; 240: Switching module; 241-246: Shift register; 250: Low-voltage to high-voltage drive module; 251-257: AND gate; 260: Speed ​​control module; 270: Pulse-width modulation control module; 280: Starter motor control module; 290: Real-time speed estimation module; Q1-Q6: Switch components; SCK: Frequency signal; SVCK: Short pulse signal; C1, C2: Capacitors. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It is obvious that the embodiments described are only embodiments of a part of the present invention, not all embodiments. However, for the description of the present disclosure, if it is determined that the detailed description makes the embodiments of the present disclosure unclear, the detailed description may be omitted. Parts not related to the description are omitted in order to specifically describe the present disclosure, and throughout the specification, the same figure numbers refer to the same components.

[0039] The term "switch component" as used herein refers to a wiring component configured to connect or disconnect current in electrical and electronic devices. Switch components may include, but are not limited to, transistors, bipolar junction transistors (BJTs), field-effect transistors (FETs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and insulated-gate bipolar transistors (IGBTs) configured to connect current based on a control signal.

[0040] See also Figure 1 , is a block diagram of the real-time sensorless motor control drive system of the present application. A real-time sensorless motor control drive system is applied to a control drive system 200 for driving a three-phase motor 100. The present application adopts a common six-step square wave control method to drive the three-phase motor 100 to rotate, which is applicable to both BLDCM and PMSM type motors. The present application is a complete motor drive control system that does not require the use of an MCU chip, a motor position sensor, and a motor speed detection device. The entire system can be easily implemented with a single chip, and a single speed control terminal facilitates the user to control the speed of the BLDCM / PMSM three-phase motor 100. The control drive system 200 includes:

[0041] The three-phase inverter module 210 is configured to convert a DC input voltage (Vdc) into a three-phase AC voltage and supply the three-phase AC voltage to the three-phase motor 100. The three-phase inverter module 210 is configured to control the speed of the three-phase motor 100 by controlling the voltage duty cycle using six switching elements Q1 through Q6. In the illustrated example, the switching elements Q1 through Q6 are metal oxide silicon field effect transistors (MOSFETs) (power MOSs). The six power MOS switching elements Q1 through Q6 are connected in a conventional inverter configuration. In addition to being connected to a power supply VM (Vdc) and outputting U / V / W power supply voltages to drive the three-phase motor 100, the gate terminals of the six power MOS switching elements Q1 through Q6 are UH / UL / VH / VL / WH / WL.

[0042] The back-electromotive force detection module 220 detects the center point of the back-electromotive force switching from the output terminals (U / V / W) of the three-phase inverter and generates a fixed-period frequency signal SCK. The frequency signal is regularly synchronized with a frequency three times the back-electromotive force frequency of the three-phase motor 100, thereby obtaining the six back-electromotive force switching point positions of the three-phase motor 100 at six multiples of 60 degrees.

[0043] The back EMF waveform of the three-phase motor 100, whether it is a trapezoidal wave, a sine wave, or any other 360-degree repeating waveform, is known to have two intersection points with a reference center value. Based on this characteristic, the positions of the six intersection points within the 360-degree cycle, namely 0 degrees (or 360 degrees), 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees, are determined and converted into a frequency signal. That is, each half cycle represents the time it takes for the three-phase motor 100 to rotate 60 degrees.

[0044] Please refer to Figure 2The three driving power lines U / V / W of the three-phase motor 100 are first connected to the positive terminal of the voltage comparator 221 after passing through the RC filtering circuit. At the same time, they are connected to a reference point N (reference voltage, generally 1 / 2 of the power supply voltage Vdc) through a resistor network. This point N is connected to the negative terminal of the voltage comparator and a capacitor is placed for voltage stabilization. Three voltage comparators determine the switching points of the voltage potentials at points U / V / W and N (i.e., the center point of the back EMF switching mentioned above), respectively, and generate high and low voltage level conversion outputs. The next stage of voltage comparator 221 is connected to a monostable multivibrator 222, which produces three square wave signals with a phase difference of 120 degrees. These three square wave signals are input to an OR gate 223 to be combined into a single signal, which drives a D-type register 224 whose output is inverted and connected to the input. The result is a fixed-cycle frequency signal SCK. This frequency signal SCK is regularly synchronized with three times the frequency of the motor's back EMF, and each half cycle represents the time it takes for the motor to rotate 60 degrees.

[0045] Please refer to Figure 3 The angle shift module 230 is configured to shift the aforementioned frequency signal SCK by 30 degrees to obtain a short pulse signal SVCK that shifts the aforementioned six back electromotive force switching points by 30 degrees, and each short pulse signal SVCK differs by 60 degrees in motor rotation angle.

[0046] The above frequency signal SCK can be used to obtain the six switching points of the motor's back electromotive force. According to the six-step square wave commutation operation method, the six commutation points can be obtained by shifting these six switching points by 30 degrees. Figure 3 The proposed circuit architecture uses two constant current charge and discharge circuits 231 and 232 to charge and discharge the two capacitors C1 and C2 to calculate the time. Since the frequency signal SCK is the frequency signal of the motor rotating 60 degrees, it is given to a charge and discharge timing circuit respectively. First, let's look at the constant current charge and discharge circuit 231. The half cycle of the frequency signal SCK is the time for the motor to rotate 60 degrees, which is T. 60 , the charging current is I1, the capacitor C1 is charged from 0V to the end of the first half cycle, and the voltage V1 is obtained. The value of V1 represents the time required for the motor to rotate 60 degrees; the second half cycle of the frequency signal SCK allows the capacitor C1 to discharge, and the discharge current I2 is set to 2 times the charging current I1. According to the capacitor constant current charge and discharge formula 1, the discharge time T is obtained. 30 T 60 Half of the time, which is equivalent to the time it takes for the motor to rotate 30 degrees.

[0047]

[0048] Similarly, another constant-current charge-discharge circuit 232 records the time it takes for another motor to rotate 60 degrees and the time it deviates by 30 degrees. However, this method uses the inverted frequency signal SCK for counting. This method offers the advantage of real-time feedback of the motor's rotation angle, measuring every 60 degrees and simultaneously calculating the time it takes for a 30-degree offset. This eliminates any delays caused by microprocessor (MCU) algorithms or software interrupts. Furthermore, the discharge current I2 can be arbitrarily set to a different offset angle. For example, if I2 = 3 * I1, a faster discharge results in a 20-degree offset, while if I2 = 1.5 * I1, a slower discharge results in a 40-degree offset.

[0049] The output signals VA / VB of the two current charge and discharge circuits 231 and 232 are connected to two comparators 233 and 234 and then pass through a bistable multivibrator (SR latch) 235 to generate a frequency signal with a 30-degree offset. The signals are then modulated by a monostable multivibrator 236 to generate a short pulse signal SVCK with a 30-degree offset, where each short pulse has a 60-degree difference in the motor's rotation angle.

[0050] See also Figure 4 , the signal SCK / SVCK input and output waveforms, it can be clearly seen that the difference between the short pulse signal SVCK and the frequency signal SCK is that the high and low transitions of the frequency SCK will be delayed by half of the cycle time T 30 Whether the frequency signal SCK changes from low to high or from high to low, the delay time T will be 30 .

[0051] The switching module 240 uses the short pulse signal SVCK as a time switching signal, switching every 60 degrees. After six switching cycles totaling 360 degrees, this six-step switching sequence is repeated to complete the six-step square wave commutation. The low-voltage to high-voltage (LV to HV) driver module 250 performs a pulse width modulation (PWM) function after the six-step square wave commutation, and accordingly outputs the signals required to control the switching elements (gate terminals of the power MOS) of the three-phase inverter module 210, thereby achieving control and drive of the three-phase motor 100.

[0052] See also Figure 5 and Figure 6 The short pulse signal SVCK obtained by the aforementioned sensorless back EMF detection method can be directly used as the commutation point of the six-step commutation. Therefore, the purpose of six-step square wave control can be achieved by using the short pulse signal SVCK as the frequency to drive the six shift registers.

[0053] Six-step square wave commutation using the shift register method Figure 5As shown, the short pulse signal SVCK is input to the frequency of the 6-bit shift registers 241 to 246, and the values ​​of the fifth and sixth shift registers 245 and 246 are preset to high (Vdc), and the values ​​of the remaining shift registers 241 to 244 are preset to low (0V). That is, the memory values ​​D6, D5, D4, D3, D2, and D1 of the shift registers 246 to 241 are 110000 respectively. According to the characteristics of the shift registers 241 to 246, Each frequency cycle shifts, passing the register value to the next register. Therefore, the memory values ​​D6, D5, D4, D3, D2, and D1 are output in time sequence as 110000 → 100001 → 000011 → 000110 → 001100 → 011000 → 110000, repeating over and over again. A switch is made every 60 degrees, for a total of six switches, 360 degrees. This six-step switching sequence is repeated over and over again, completing the six-step square wave commutation.

[0054] In practice, the low voltage to high voltage driver module 250 is as follows Figure 6 As shown in the circuit diagram, the low-voltage to high-voltage driver module 250 connects the shift registers 246-241 to the corresponding switching elements of the three-phase inverter module 210 via six AND gates 251-256, generating control signals for the six switching elements Q1-Q6 that control the three-phase motor drive. In practice, by appropriately connecting to the corresponding driver stages, gate control signals for the six power-stage switching elements Q1-Q6 that drive the three-phase motor 100 are generated. In the diagram, the gate terminals of the U-phase upper / lower power MOSs (Q1 and Q4) are UH / UL, the gate terminals of the V-phase upper / lower power MOSs (Q2 and Q5) are VH / VL, and the gate terminals of the W-phase upper / lower power MOSs (Q3 and Q6) are WH / WL. These gates, combined with the logic functions of AND gates 251-256 and 257, control the on / off switching of AND gates 251-256, enabling pulse width modulation (PWM) functionality.

[0055] See Figure 7 In the input / output waveform diagram, UH / UL, VH / VL, and WH / WL are controlled by the short pulse signal SVCK. Because the three-phase motor 100 rotates 60 degrees, the corresponding outputs are the signals required to control the six power stage MOS gates of the switching components Q1 to Q6. These signals change regularly according to the six-step square wave commutation method. Within one cycle of the short pulse signal SVCK, only one xH (UH / VH / WH) and one xL (UL / VL / WL) operating switching waveforms appear, and the xH and xL of the same phase are never turned on at the same time.

[0056] The six power-stage MOSFETs in this embodiment utilize a common inverter connection. In addition to connecting to power source VM and outputting U / V / W power voltages to drive the motor, they also feature six gate terminals, UH / UL / VH / VL / WH / WL. A series sense resistor, Rs, is placed at the motor drive current as required. The back-EMF detection module 220 and angle offset module 230 are described above, specifically the CU / CV / CW signals, which require an external filter capacitor, C. A six-step square-wave commutation method is implemented within the switching module 240 and the low-voltage to high-voltage (LV to HV) driver module 250 to drive the gates of the power-stage MOSFETs within the three-phase inverter module 210.

[0057] In practical applications, the control drive system 200 for driving the three-phase motor 100 also includes a speed control module 260 and a pulse width modulation control module 270. The speed control module 260 is used to receive external speed commands and generate control signals to the pulse width modulation control module 270, so that the pulse width modulation control module 270 can control the output pulse duty cycle.

[0058] In practical applications, the control drive system 200 for driving the three-phase motor 100 also includes a starting motor control module 280 and a real-time speed estimation module 290, forming two motor control loops: a speed control loop and a current control loop. Additionally, there is a motor position control loop. The speed control loop ensures that the motor speed is consistent with the user-set value. The current control loop provides the motor with a current value corresponding to the speed loop's requirements. The position control loop generates a control signal corresponding to the motor's real-time position.

[0059] See also Figure 8 , which is a corresponding diagram of the input and output waveforms of the motor position control loop. The six switching points of the U / V / W back EMF waveform are detected in sequence and reflected on the frequency signal SCK. After a 30-degree angular offset, the commutation frequency signal SVCK is generated. SVCK is used to convert the short pulse signal SVCK into the commutation point. A six-step square wave commutation operation is performed to obtain the U / V / W voltage output waveform to the driver stage and the corresponding motor feedback current waveform I U , I V , I W , achieving the motor position control loop effect.

[0060] See also Figure 9 In practice, when the three-phase motor 100 is initially stationary, the starter motor control module 280 uses a variable voltage that gradually increases from small to large to control the frequency signal frequency from slow to fast. The control voltage gradually increases from small to large to control the frequency of the short pulse signal SVCK of the angle offset module 230 from small to large, providing frequency operation for driving the three-phase motor 100.

[0061] Because the motor is initially stationary and there is no back-EMF signal to sense, an open-loop method is used to slowly rotate the motor step by step. Once the back-EMF energy is within the detection range, the position control loop is switched to control. Because the six-step square wave drive is controlled by the frequency signal SCK, its waveform resembles a general frequency signal. In practice, a common voltage-controlled frequency circuit (VCO) (not shown) can be used to generate the STCK signal. The frequency is then gradually increased by increasing the voltage, driving the motor to slowly increase. A variable voltage is used to gradually control the frequency signal from slow to fast. This allows the control voltage to gradually increase, i.e., a small current is used to charge the external capacitor, thereby controlling the STCK signal frequency from slow to fast. The starter motor control module 280 uses the duty cycle to determine whether the high / low duty of the frequency signal SCK is close to 50% / 50%, which means the back electromotive force signal is stable (DutyOK). The DutyOK signal switches the multiplexer (not shown in the figure). Finally, the open loop controlled by the STCK signal enters the closed loop operation controlled by the frequency signal SCK, providing the motor with a frequency operation for driving. The output waveform is as follows: Figure 9 shown.

[0062] The real-time speed estimation module 290 utilizes the aforementioned fixed-cycle frequency signal SCK. Each half-cycle time is the motor's 60-degree rotation angle characteristic, that is, three times the frequency signal SCK time period is the frequency calculation for one rotation of the motor. The real-time speed estimation module 290 uses a frequency-to-voltage converter (Frequency-to-Voltage Converter) to count this frequency. This type of circuit can convert the input frequency signal into a voltage signal in real time, that is, different voltages represent different motor rotation speeds. In the implementation application, the circuit using a common frequency-to-voltage converter (Frequency-to-VoltageConverter) (not shown in the figure) is used, where the speed is represented by the ratio of the voltage size. The short pulse signal SVCK frequency is a pulse wave for every 60-degree rotation of the motor. The input and output discharge constant currents are controlled in sequence, and the N_VF voltage (representing the speed) can be calculated. The faster the frequency signal SCK frequency, the higher the N_VF voltage. The output waveform is as follows: Figure 10 shown.

[0063] The operational flow of this embodiment of the real-time sensorless motor control drive system is as follows: after a user sets a speed command, the three-phase motor 100 is initially started from a standstill using the aforementioned open-loop startup mechanism. A determination mechanism within the startup motor control module 280 indicates that the motor back-EMF frequency signal SCK is sufficiently large to be detected. The six U / V / W back-EMF switching points are then detected to generate a periodic frequency signal SCK corresponding to a 60-degree motor rotation angle. The angle shift module 230 then uses two capacitors to shift these switching points to the appropriate angle, generating a short pulse signal SVCK at the commutation point. This short pulse signal SVCK serves as the frequency control signal for the six offset registers in the switching module 240, generating a six-step square wave drive switching operation signal. The low-voltage to high-voltage (LV to HV) driver module 250 then controls the switching elements (gate terminals of the power MOSFETs) of the three-phase inverter module 210, driving the six power components in the three-phase inverter module 210, thereby rotating the three-phase motor via the U / V / W power lines.

[0064] The real-time speed estimation module 290 observes the switching point frequency signal generated by the U / V / W lines when the three-phase motor 100 rotates and converts it into a voltage form in real time to represent the motor speed. The speed control module 260 then compares and determines the speed control loop to increase or decrease the current command to meet the speed command set by the user.

[0065] At the same time, the current command size adopts a common current PWM control loop. The pulse width modulation control module 270 detects the voltage of the resistor connected to the three-phase inverter module 210 that senses the motor current size. After determining the current of the three-phase motor 100, it compares it with the current and determines whether to increase or decrease it. It then issues a voltage command to the switching module 240 of the six-step square wave drive control and the low voltage to high voltage (LV to HV) drive module 250 to increase or decrease the signal width (pulse width).

[0066] This sensorless motor control drive system utilizes the back electromotive force characteristics of a three-phase motor to detect six switching point positions, and finds the commutation points of a six-step square wave by rotating the motor 30 degrees with an offset, performing motor position commutation operations. A frequency-to-voltage converter is used to count the speed in real time, eliminating the mathematical delays of a microprocessor (MCU) or the time-consuming calculations caused by computer software interruptions. The system responds to the motor position and speed in real time and provides corresponding current command control, resulting in excellent controllable characteristics.

[0067] The sensorless motor control drive system proposed in this disclosure can effectively and efficiently drive motor rotation in real time, implementing functions such as position control loops, current PWM control loops, and speed control loops. This system eliminates the need for microprocessors (MCUs) or SoC digital logic, and components such as position and speed sensors, achieving drive control at a low implementation cost. Furthermore, this system can be implemented using FPGAs and SoCs, allowing for integration into a single chip. This single-chip solution facilitates direct integration into printed circuit boards (PCBs), allowing users to easily achieve speed control.

[0068] The above embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. A real-time sensorless motor control drive system for driving a three-phase motor, characterized in that: The control drive system includes: a three-phase inverter module configured to convert a DC input voltage into a three-phase AC voltage and supply the three-phase AC voltage to a three-phase motor; The back-EMF detection module is configured to detect the center point of back-EMF switching from the output terminals of the three-phase inverter and generate a fixed-cycle frequency signal. The frequency signal is regularly synchronized with three times the back-EMF frequency of the three-phase motor to determine the six back-EMF switching points of the motor at six 60-degree multiples. An angle shift module is configured to shift the frequency signal by 30 degrees to generate short pulse signals that are 30 degrees offset from the switching points of the six back electromotive forces, with each short pulse signal having a time difference of 60 degrees of the motor rotation angle; The switching module is configured to use a short pulse signal as the time switching signal, switching every 60 degrees, and after six switching steps of 360 degrees, repeating this six-step switching sequence to complete the six-step square wave commutation; and The low-voltage to high-voltage drive module is configured to perform pulse width modulation after six-step square wave commutation. The corresponding output controls the switching components of the three-phase inverter module to achieve the control and drive of the three-phase motor.

2. The real-time sensorless motor control drive system according to claim 1, wherein: The control drive system includes a speed control module and a pulse width modulation control module. The speed control module is used to receive external speed instructions and generate a control signal to the pulse width modulation control module, so that the pulse width modulation control module can control the output pulse duty cycle.

3. The real-time sensorless motor control drive system according to claim 1, wherein: The control drive system includes a starter motor control module. When the three-phase motor is initially stationary, the starter motor control module uses a variable voltage that gradually increases from small to large to control the frequency signal frequency from slow to fast. The control voltage gradually increases from small to large, thereby controlling the frequency of the short pulse signal of the angle offset module from small to large, providing frequency operation for driving the motor.

4. The real-time sensorless motor control drive system according to claim 1, wherein: The control drive system includes a real-time speed estimation module, which uses the aforementioned fixed-cycle frequency signal. Each half-cycle time is 60 degrees of the motor's rotation angle characteristic, that is, three times the frequency signal time period is the frequency calculation of one motor rotation.

5. The real-time sensorless motor control drive system according to claim 4, wherein: The real-time speed estimation module uses a frequency-to-voltage converter to count the frequency and express the motor speed in voltage.

6. The real-time sensorless motor control drive system according to claim 1, wherein: The back-EMF detection module comprises three voltage comparators, each of which determines the difference between the three-phase AC voltage and the center point. These three comparators determine the switching point between the output terminals and the center point, generating a high- and low-voltage level switching output. The voltage comparators are connected to a monostable multivibrator at the next stage, which produces three square wave signals with a phase difference of 120 degrees. These three signals are input to an OR gate, combined into a single signal that drives a D-type register whose output is inverted and connected to the input, producing a fixed-period frequency signal.

7. The real-time sensorless motor control drive system according to claim 1, wherein: The angle-shift module uses two constant-current charge-discharge circuits to calculate the charge and discharge time of two capacitors. Each constant-current charge-discharge circuit is assigned a charge-discharge timing circuit. One of the charge-discharge circuits charges the capacitor during the first half of the frequency signal's cycle and discharges it during the second half. The discharge current is set at twice the charging current, resulting in a discharge time that is half the charging time, equivalent to the time it takes for the motor to rotate 30 degrees.

8. The real-time sensorless motor control drive system according to claim 7, wherein: Another set of charging and discharging circuits in the angle offset module uses the inverted frequency signal to count and record the time it takes for another motor to rotate 60 degrees and the 30-degree time offset.

9. The real-time sensorless motor control drive system according to claim 7, wherein: The two sets of charge and discharge output signals of the angle shift module are connected to two comparators and then passed through a bistable multivibrator to produce a frequency signal with a 30-degree offset. This is then modulated by a monostable multivibrator to produce a short pulse signal with the same offset. Each short pulse signal has a 60-degree difference in the motor's rotation angle.

10. The real-time sensorless motor control drive system according to claim 1, wherein: The switching module is a 6-bit shift register that pulls the short pulse signal into the frequency input of the 6-bit shift register. Due to the characteristics of the shift register, each frequency cycle will shift, passing the register value to the next level of register. The register value is passed to the next level of register. The switching module switches every 60 degrees, and after six switching steps for a total of 360 degrees, this six-step switching sequence is repeated to complete the six-step square wave commutation.

11. The real-time sensorless motor control drive system according to claim 10, wherein: The shift register of the switching module is pre-set to have two register values ​​at high potentials, and the other shift registers are pre-set to have low potentials.

12. The real-time sensorless motor control drive system according to claim 10, wherein: The low-voltage to high-voltage drive module is connected to the switch components of the corresponding three-phase inverter module through six AND gates, obtaining control signals for the six switch components that control the three-phase motor drive. Due to the AND gate logic function, the AND gate switches can be controlled to function as pulse width modulation.

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