TWI659602B - Brushless motor torque position coding device - Google Patents

Abstract

The invention relates to a brushless motor torque position encoding device, which includes a motor position encoder, a controller, a code selector and a PWM drive circuit. The motor position encoder is connected to a motor to measure the angular displacement of the motor rotor. Generate a UVW signal and an ABI signal; the controller is used to estimate the position angle of the motor rotor; the code selector is connected to the UVW signal and ABI signal of the motor position encoder. When the motor starts, it receives the switching signal output by the controller and selects the UVW signal Transmission to the controller. When the controller judges that the UVW signal is in a specific interval, it receives the switching signal output by the controller and selects the ABI signal to transmit to the controller. This can quickly and accurately calculate the current position angle of the motor rotor, so that the controller It can drive the motor rotor and can operate according to torque control.

Description

Brushless motor torque position coding device

The invention relates to a torque position coding device for a brushless motor, and more particularly to a coding device for estimating the torque position of a rotor of a brushless motor. To facilitate accurate control of subsequent motor torque.

The brushless DC motor consists of a rotating permanent magnet (rotor) and three or more fixed coils (stator) with the same pitch. By controlling the current in the stator coil, a magnetic field of any direction and magnitude can be produced. The attraction and repulsion of the magnetic field of the rotor and the stator on the rotating shaft, that is, generating torque. The brushless DC motor control system needs to use the angular displacement measurement results of the rotor to establish a set of closed-loop feedback loops. This measurement can be performed by a magnetic position sensor or a light position sensor. The measurement result of the angular displacement of the rotor is fed back to the controller, and the current flowing through the stator coil is controlled to generate a quadrature magnetic field to drive the rotor to rotate. By measuring the angular displacement of the rotor, it can be fed back to the system that controls the stator coil current, thereby achieving precise control of the rotor torque.

The encoder used to measure the position angle of the brushless motor, as shown in the block diagram of the conventional motor torque encoding circuit in Figure 1, is a conventional UVW signal combined with the ABI signal of the Quadrature Encoder Interface (QEI). Encoding, the UVW signal can only divide the motor rotation into six sections, and the ABI can accurately estimate the angle of the brushless motor 1 Degree position. Therefore, in the conventional motor position encoder 2, in addition to providing UVW signal input to the controller 3, it also has a quadrature encoder (QEI) encoding function, which can provide information about the mechanical angle of the motor, including phase A (QEA). Three signals (ABI) of Phase B, QEB and Index are input to the controller 3. Therefore, the conventional motor position encoder 2 must have six pin outputs. When the controller 3 receives the UVW signal and the ABI signal output from the motor position encoder 2, it will output a control signal to the PWM drive circuit 4, and the PWM drive circuit 4 outputs a drive current for controlling the stator coil of the brushless motor 1 to drive the Rotor rotation angle or torque of the brush motor 1.

However, when the controller 3 reads the ABI signal, it needs to know the starting position of the brushless motor 1 by the Index signal, and the Index signal must rotate the rotor of the brushless motor 1 to the "zero point" set by the encoder. It only appears when the position is set. If the brushless motor 1 is not in the “zero” position when starting, the controller 3 cannot know the current position angle of the rotor, resulting in subsequent control processes that cannot accurately control the torque of the motor. The position encoder 2 has the disadvantage that the position angle of the motor rotor cannot be accurately calculated when the motor is in the starting state. The ABI signal must be correctly read after the motor rotor has rotated more than one turn, so it takes a long time to calculate Time, which is intolerable for the need for fast and precise motor torque control systems, so there is great room for improvement.

In order to solve the lack of knowledge, the main purpose of the present invention is to propose a brushless motor torque position coding device, which includes a motor position encoder, a controller, a code selector, and a PWM drive circuit, wherein the motor position code The controller is connected to a motor to measure the angular displacement of the motor rotor to generate a UVW signal and an ABI signal; the controller is used to estimate the position angle of the motor rotor; the code selector is connected to the UVW signal and ABI signal of the motor position encoder. Receive the switching signal output from the controller when it reaches the start, select the UVW signal and send it to the controller. When the controller judges that the UVW signal is in a specific interval, receive the switching signal output from the controller and select the ABI signal to send it to the controller. Accurately calculate the current position angle of the motor rotor, so that the controller can drive the motor rotor to operate in accordance with torque control.

1‧‧‧Brushless motor

2‧‧‧ Motor position encoder

3‧‧‧ Controller

4‧‧‧PWM drive circuit

10‧‧‧ Motor

11‧‧‧ Motor position encoder

12‧‧‧ Controller

13‧‧‧Code selector

14‧‧‧PWM drive circuit

FIG. 1 is a block diagram of a conventional brushless motor torque encoding circuit.

FIG. 2 is a schematic circuit block diagram of a brushless motor torque position encoding device according to the present invention.

FIG. 3 is a schematic circuit diagram of an embodiment of a coding selector according to the present invention.

FIG. 4 is a schematic diagram of a control flow of a controller of the present invention.

FIG. 5A is a schematic diagram of a UVW signal waveform according to the present invention.

FIG. 5B is a schematic diagram of a switching signal waveform according to the present invention.

FIG. 5C is a schematic diagram of an ABI signal waveform according to the present invention.

Please refer to FIG. 2, which is a block diagram of a torque position coding device for a brushless motor according to the present invention. The present invention is mainly used to accurately calculate the position angle of the rotor of the motor 10 to drive the precise position of the rotor of the motor 10 according to the control torque. Therefore, the present invention includes a motor position encoder 11, a controller 12, and a code selector 13. And a PWM drive circuit 14. The motor position encoder 11 is connected to the rotor of the motor 10 to measure the angular displacement of the rotor of the motor 10, and can generate a set of UVW signals and a set of ABI signals. As shown in FIG. 5A, it is a schematic diagram of the UVW signal waveform. The UVW signal is a Hall signal that can rotate the rotor of the motor 10 360 degrees into six sections, each section is 60 degrees, as shown in Table 1 below, which is the section value defined in the embodiment of the present invention.

X: This combination does not appear

Figure 5C shows the waveform of the ABI signal. The ABI signal is obtained from the starting position of the motor 10 by the I signal. The A and B signals will count the angular displacement of the rotor in pulses. For example, when the A and B phases When the set magnification is 1, each pulse (Pulse) counted by phase A and phase B signals is 1 degree of rotation of the rotor of the motor 10. When the A phase and B-phase pulse (Pulse) number is 500, ABI 333 times the resolution of signals UVW signal (500 * ^22/333 = 6).

Although the ABI signal can accurately calculate the angular position of the rotor of the motor 10, it cannot be calculated when the motor 10 starts. Therefore, the present invention first uses the UVW signal to calculate the interval of the rotor of the motor 10, and defines the UVW signal as a unit when it is converted to a specific interval. The commutation point, and this commutation point is the "zero" position of the ABI signal. Therefore, when the motor 10 is in the starting state, only the UVW signal is read first, and the ABI signal is read when it reaches the commutation point. The angular position of the rotor of the motor 10 can be quickly and accurately calculated.

Therefore, please refer to FIG. 2, FIG. 3, FIG. 4, and FIGS. 5A, B, and C of the present invention. In the circuit of the embodiment of FIG. 2 of the present invention, the controller 12 can reduce three input terminals compared with the conventional circuit. A code selector 13 can be switched to the ABI signal when the UVW signal reaches the "commutation point". FIG. 3 is a circuit diagram of an embodiment of the coding selector 13 of the present invention, and FIG. 4 is a UVW signal of the present invention. Schematic diagram of control flow for switching to ABI signal.

The controller 12 of the present invention has only three input terminals, a switching control terminal (CS) and three output terminals. The controller 12 can calculate the position angle of the rotor of the motor 10 to precisely control the rotor torque of the motor 10, The coding selector 13 has six input terminals, which are respectively connected to the UVW signal and the ABI signal of the motor position encoder 11. The PWM driving circuit 14 is connected to the three output terminals of the controller 12 and the stator coil windings of the motor 10. The PWM driving circuit 14 receives the torque control of the controller 12 and outputs a control current to the stator coil windings to drive the rotor of the motor 10 to rotate. Moment control operation.

In the embodiment shown in FIG. 4, when the motor 10 is in the starting state (flow 100), the controller 12 first sets the switching control terminal (CS) to 0, that is, to read the UVW signal (flow 110), and the code selector 13 receives The "0" switching signal of the switching control terminal (CS) output by the controller 12, the code selector 13 selects the UVW signal output and transmits it to the input terminal of the controller 12. At this time, the controller 12 judges the motor 10 based on the UVW signal. If the position where the rotor is located reaches the "commutation point" (process 120), if the "commutation point" is not reached, the rotor continues to rotate, and the controller continuously judges whether the UVW signal reaches the "commutation point".

When it is determined that the UVW signal has reached the "commutation point", the controller 12 switches the switching signal (CS) to "1", that is, it switches to the ABI signal (flow 130), and the code selector 13 receives The "1" switching signal output from the controller 12 selects the ABI signal output and transmits it to the input terminal of the controller 12. At this time, after receiving the ABI signal, the controller 12 first confirms whether the angle is correct (process 140). If it is incorrect, it indicates that the rotor of the motor 10 has not reached the "zero point", and then switches back to read the UVW signal. This process is to avoid interference. The wrong torque angle is calculated. If the controller confirms that the angle is correct, the controller 12 outputs torque control to the PWM drive circuit 14, and the PWM drive circuit 14 The torque control is performed (flow 150), and the control current is switched out to drive the motor 10 to operate stably in accordance with the torque control (flow 160).

Please refer to FIG. 5A, FIG. 5B, and FIG. 5C together. FIG. 5A is a waveform diagram of UVW signals according to an embodiment of the present invention, FIG. 5B is a waveform diagram of switching signals according to an embodiment of the present invention, and FIG. ABI signal waveform chart. The phase interval of the UVW signal in FIG. 5A is shown in Table 1. It is divided into six intervals. In this embodiment, the transition from the sixth phase interval to the first phase interval is defined as a “commutation point”, that is, in the ABI signal. The "zero" position of the I signal, in other words, when the rotor turns to the "commutation point" of the UVW signal, the signal of the switching control terminal (CS) will change from "0" to "1", and the code selector 13 switches to ABI signal output, controller 12 reads the ABI signal to estimate the corresponding rotor position angle of the motor 10. The A and B phases of the ABI signal will increase according to the set magnification of the controller 12, and the waveforms of the A and B phases will also increase. The controller 12 detects the "0,1" changes (pulses) of the A and B phases to accurately calculate the current position angle of the rotor.

In summary, the brushless motor torque position encoding device of the present invention reduces the input pins of the encoder compared with the conventional controller, and changes the pin from 6 Pin to 4 Pin to reduce the cost. According to the motor speed, the UVW is controlled by the control logic method. The signal is switched to the ABI signal, which can increase the efficiency of the motor, without waiting for the angle of the rotor to rotate once, and reduce the alignment time of the motor. Therefore, the present invention is not only technically innovative, but also enhances the above-mentioned multiple effects over conventional items. It should be submitted in accordance with the law with statutory patent elements that are fully in line with novelty and progress. We urge your office to approve this invention patent case. Inspired by invention, to the sense of virtue.

Claims (5)

A brushless motor torque position encoding device includes: a motor position encoder connected to a motor to measure the angular displacement of the motor rotor to generate a UVW signal and an ABI signal; a controller having an input end, Switching the control end and the output end for estimating the position angle of the motor rotor; and a coding selector having an input end connected to the UVW signal and the ABI signal of the motor position encoder respectively, and receiving the controller when the motor starts A switching signal output from the switching control terminal is selected to transmit the UVW signal to the input of the controller. When the controller judges that the UVW signal is in a specific interval, it receives the switching signal output from the controller and selects the ABI signal to transmit To the input of the controller. The torque position coding device of the brushless motor according to claim 1, further comprising: a PWM driving circuit connected to the output terminal of the controller and a stator coil winding of the motor, and receiving a torque control of the controller. , Driving the motor rotor to operate in accordance with torque control. The brushless motor torque position encoding device according to claim 1, wherein the UVW signal output by the motor position encoder is a 360-degree rotation of the motor rotor into six sections, each section being 60 degrees, set The UVW signal is a commutation point when converted to the specific interval. The torque position coding device for a brushless motor as described in claim 3, wherein the commutation point is the "zero" position of the ABI signal, that is, the I signal (start counting signal) in the ABI signal is generated, so that the ABI signal The phase A signal and phase B signal start to count an angle pulse. When the phase A and phase B signals are set to 1, each angle pulse of the phase A signal and phase B signal is 1 degree of the rotation of the motor rotor. angle. The torque position coding device for a brushless motor according to claim 1, wherein when the controller starts, the switching control terminal outputs the switching signal to the coding selector, and controls the coding selector to select the UVW signal transmission Go to the input terminal of the controller to read the UVW signal and determine whether the rotor of the motor has turned to a commutation point. When it reaches the commutation point, the switching control terminal outputs the switching signal to the code selector. , Controlling the code selector to select the ABI signal to be transmitted to the input terminal of the controller, so as to read the ABI signal and calculate the position angle of the motor rotor.