WO2009048292A2

WO2009048292A2 - Control apparatus and method for bldc hub motor

Info

Publication number: WO2009048292A2
Application number: PCT/KR2008/005970
Authority: WO
Inventors: Dong Ryul Shin
Original assignee: E & I Co, Ltd
Priority date: 2007-10-11
Filing date: 2008-10-10
Publication date: 2009-04-16
Also published as: WO2009048292A3; KR100827414B1

Abstract

A control apparatus and method for a brushless direct current hub motor are provided. The control apparatus for a brushless direct current hub motor includes an input unit generating a forward/reverse RPM control command of the motor, a sensor unit detecting rotation of the motor, a controller outputting a motor driving signal by combining a motor rotational signal of the sensor unit with the RPM control command of the input unit, a switching device unit supplying a driving current to the motor by performing switching operation in accordance with the combined signal, and a brushless direct current hub motor rotating by the driving current. The brushless direction current hub motor has a multi-phase independent parallel winding. The controller drives the switching device unit such that a switching-on time of a lower end signal of the H-bridge is longer than a switching-on time of an upper end signal of the H-bridge to eliminate residence power of a motor coil. An apparatus/method is provided. The residence current of the motor coil can be eliminated and thus hysteresis phenomenon can be prevented.

Description

CONTROL APPARATUS AND METHOD FOR BLDC HUB

MOTOR

Technical Field

[1] The present invention relates to a control apparatus and method for a brushless direct current (BLDC) hub motor and, more particularly, to a control apparatus and method for a BLDC motor, which uses a permanent magnet as a rotor, forms a stator winding in a multi-phase independent parallel structure, and controls distributed power. Background Art

[2] Generally, a brushless direct current (BLDC) motor is designed to generate torque by interaction between a rotational magnetic field generated by a stator with a 3 -phase coil and a magnetic field generated by a rotor to which a permanent magnet is attached.

[3] The BLDC motor has all of advantages of direct current motors such as running convenience, easy controllability of an RPM, and the like and the number of RPM, easily controllable and does not use a brush that is a shortcoming in the direct current motor, thereby reducing noise and maintenance costs. Therefore, the BLDC motor has been widely used in a variety of different fields.

[4] The BLDC motor detects a position of the rotor and applies a control signal to a power driving module in accordance with the detected position of the rotor to apply a proper current to the 3 -phase coil of the stator, thereby generating the torque by the interaction between the magnetic field of the rotor and the magnetic field generated by the current applied to the stator.

[5] The detection of the position of the rotor is essential for the rotation of the BLDC motor. In order to detect the position of the rotor, a hole sensor that varies in its potential difference depending on a variation of magnetic flux is used or a current transformer is installed on each phase.

[6] Further, Korean Patent No. 07258111 (May 31 , 2007) discloses such a BLDC motor.

[7] That is, a driving apparatus of the BLDC motor of the patent includes a rectifying unit 12 rectifying a current from an alternating current (AC) power source 10, a power module 22 having a plurality of switching devices, a power module driving unit 14 outputting on/off signals of the switching devices of the power module 22, and a controller 16 outputting driving control signals to the power module driving unit 14 and the power module driving unit 14.

[8] In addition, in order to detect a position of a rotor using counter electromotive force applied to a stator, the driving apparatus further includes a position detecting unit 18 having a plurality of comparators outputting zero crossing point detecting signals by comparing a reference voltage with the counter electromotive force. [9] Reference numerals 20a to 20c indicate 3-phase coils of the stator and reference numerals 22a to 22c denotes sub-windings that are further wound around the 3-phase coils to detect the position of the rotor. [10] The Korean Patent No. 07258111 discloses a technique for conveniently driving and controlling the BLDC motor without using a complicated algorithm such as a vector control by detecting the counter electromotive force using the sub-windings and by using the position detecting unit as it is.

Disclosure of Invention

Technical Problem [11] However, the technique disclosed in the Korean Patent No. 07258111 has a problem in that, since a 3-phase linear winding is formed on the stator, high speed high torque driving cannot be realized due to a current limitation caused by a high coil resistance value. [12] Further, the technique disclosed in the Korean Patent No. 07258111 has a problem in that, since a controllable electric current application method is designed to generate the counter electromotive force in the form of a sine wave, a square wave, or a trapezoidal type when starting and stopping the motor, it is difficult to make up and control the controller.

Technical Solution [13] The present invention has been made in an effort to solve the above-described problems. An object of the present invention is to provide a control apparatus and method for a BLDC hub motor, in which a winding having a multi-phase independent parallel structure is formed on a stator of the motor. [14] Another object of the present invention is to provide a control apparatus and method for a BLDC hub motor, which use a controllable current applying manner that can prevent the generation of counter electromotive force of a motor coil using a rectangular manner.

Advantageous Effects

[15] According to the control apparatus and method for the BLDC hub motor of the present invention, a hysteresis phenomenon can be obviated by removing residence power from the motor coil.

[16] In addition, according to the control apparatus and method for the BLDC hub motor of the present invention, by preventing the generation of the counter electromotive force such as residence power, a drive can be simplified and costs can be reduced.

[17] Further, according to the control apparatus and method for the BLDC hub motor of the present invention, control response can be improved. Brief Description of Drawings

[18] FIG. 1 is a schematic view of a driving unit of a BLCD motor according to a related art.

[19] FIG. 2 is a block diagram of a BLDC hub motor according to an embodiment of the present invention.

[20] FIG. 3 is a block diagram of a controller depicted in FIG. 2.

[21] FIG. 4 is a view of a switching equivalent circuit of a switching device depicted in

FIG. 2.

[22] FIG. 5 is a graph illustrating timing of switching signals of the switching equivalent of FIG. 4.

[23] FIG. 6 is a connection diagram of a stator of the switching equivalent circuit of FIG.

4.

[24] FIG. 7 is a flowchart illustrating a control method for a BLDC hub motor according to an embodiment of the present invention.

[25] *Description of reference numerals of principal elements in the drawings*

[26] 101 : power source

[27] 102 : input unit

[28] 103 : controller

[29] 104 : switching device unit

Best Mode for Carrying out the Invention

[30] In one embodiment to achieve the above objects, a control apparatus for a brushless direct current hub motor includes an input unit generating a forward/reverse RPM control command of the motor; a sensor unit detecting rotation of the motor; a controller outputting a motor driving signal by combining a motor rotational signal of the sensor unit with the RPM control command of the input unit; a switching device unit supplying a driving current to the motor by performing switching operation in accordance with the motor driving signal; and a brushless direct current hub motor rotating by the driving current, wherein the brushless direction current hub motor has a multi-phase independent parallel winding; and the controller drives the switching device unit such that a switching-on time of a lower end signal of the H-bridge is longer than a switching-on time of an upper end signal of the H-bridge to eliminate residence power of a motor coil.

[31] In another embodiment to achieve the above objects, a control method for a brushless direct current motor having a multi-phase independent parallel winding includes (a) receiving a forward/reverse signal of the motor, a variable RPM command signal of the motor, and an RPM signal of the motor; (b) receiving and synchronizing the variable RPM command signal and the RPM signal of the motor; (c) combining the syn- chronized signals and outputting a motor driving signal in accordance with the combined signals, wherein a switching-on time of a lower end signal of the motor driving signal is longer than a switching-on time of an upper end signal; (d) rotating the motor using a current applied in accordance with the driving signal output; (f) determining if the variable RPM command signal of the motor is 0 and stopping, when it is determined than the variable RPM command signal of the motor is 0, the motor. Mode for the Invention

[32] Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings.

[33] FIG. 2 is a block diagram of a BLDC hub motor according to an embodiment of the present invention, FIG. 3 is a block diagram of a controller depicted in FIG. 2, FIG. 4 is a view of a switching equivalent circuit of a switching device depicted in FIG. 2, FIG. 5 is a graph illustrating timing of switching signals of the switching equivalent of FIG. 4, FIG. 6 is a connection diagram of a stator of the switching equivalent circuit of FIG. 4, and FIG. 7 is a flowchart illustrating a control method for a BLDC hub motor according to an embodiment of the present invention.

[34] As shown in FIG. 2, a control apparatus for a BLDC hub motor according to an embodiment of the present invention includes an input unit 102 inputting a forward/ reverse rotational signal and a control command output signal, a controller 103 outputting a driving signal by operating and comparing the control command output signal of the input unit 102 with a position of a rotor and an RPM signal 103, a switching device unit 104 outputting a current in accordance with the driving signal output from the controller 103, a BLDC hub motor 105 rotating by the current applied from the switching device unit 104, a sensor unit 106 detecting a position and RPM of the rotor of the BLDC motor 105, and a power source 101 supplying electric power required for the control apparatus.

[35] The power source unit receives battery power that is direct current power and supplies the received power to the switching device unit 104 and the BLDC hub motor 105 as motor driving power. The battery power is input to a direct current/direct current (DC/DC) converter and output as DC 15V logic power to a logic driving terminal of the controller 103.

[36] The input unit 102 is a variable signal input circuit for varying the RPM of the BLDC hub motor, including a variable resistor. That is, the input unit 102 varies the variable resistor to convert the 15V power into 0V~ 15V and input the converted signal to a pulse width modulation (PWM) input terminal of the controller 103.

[37] The sensor unit 106 is provided to supply the driving signal of the BLDC motor having a multi-phase (m-phase, m=2, 3, 4,—) independent parallel structure. The sensor unit 106 may include a photo interrupter sensor.

[38] The photo interrupter sensor output OV (LOW signal) when an encoder plate of the

BLDC hub motor 105, driven by a RPM command value signal for varying the RPM of the motor and the output signal of the sensor unit 106, passes through the photo interrupter sensor while rotating. When the encoder plate does not pass through the photo interrupter sensor while rotating, the photo interrupter sensor outputs +15V (HIGH signal). This signal is input to a logic IC combination unit 302 and output as Al, A2, A3, and A4 through an operation.

[39] The controller 103 includes a processor for performing a signal process and operation in the control system.

[40] As shown in FIG. 3, the controller 103 in accordance with the embodiment includes a

PWM IC 301 receiving a signal from the PWM input terminal and outputting a PWM OUT signal of a square wave, a logic IC combination unit 302 receiving the PWM OUT signal and a signal of the sensor unit 302 and combining and outputting a switching timing logic signal, and a driving unit 303 amplifying a logic signal in accordance with the switching timing logic signal from the logic IC combination unit 302.

[41] The logic IC combination unit 302 is a logic IC combination circuit that is formed by a combination of an AND gate device and a NOT gate device. The logic IC combination unit 302 receives the PWM OUT signal of the PWM IC 301 and a sensor input signal and outputs the drive driving signals Al, A2, A3, and A4 to the driving unit 302 in accordance with the operation of the logic circuit.

[42] The driving unit 303 is for driving a switching device that is formed with a H-bridge for driving an m-phase motor (m=2, 3, 4,—). The driving unit 303 receives the driving signals Al, A2, A3, and A4 of the logic IC combination unit 302 and outputs signals Ql, Q2, Q3, and Q4 for driving switching devices (eg. IGBT, GTO, TR, etc.) in the form of the H-bridge type illustrated in FIG. 4.

[43] As shown in FIG. 4, the switching device unit 104 is a 3-phase motor driving H- bridge circuit. In the case of more than 3-phase, three H-bridge drives are provided.

[44] The drive device in the switching device unit is constituted with switching devices such as a transistor, GTO, IGBT, and the like. The drive device receives the signals Ql, Q2, Q3, and Q4 output from the driving unit 303 and drives one phase of the BLDC hub motor with the multi-phase independent parallel structure.

[45] The drive device is a 3-phase driving type having three H-bridge switching devices

(A, B, and C switching devices) for driving three motors, i.e., three motor coils 401, 402, and 403.

[46] Among the switching device driving signals Ql, Q2, Q3, and Q4, the switching device driving signals Ql and Q2 are upper end signals of the H-bridge and the switching device driving signals Q3 and Q4 are lower end signals of the H-bridge. After the switching device driving signals Ql and Q2 are turned on, the switching device driving signals Q3 and Q4 are turned on.

[47] The lower end signal Q4 has a longer switching time than the upper end signal Ql to extract the residence power remained on the motor coils 401, 402, and 403, thereby obviating the hysteresis phenomenon.

[48] As a result, the counter electromotive force that has been generated in the current motors is eliminated and there is no need for a complicated drive to prevent the generation of the counter electromotive force in the present invention. That is, the drive is formed in a simple structure and the manufacturing costs of the drive can be reduced. In addition, a response property to the control is excellent.

[49] In Fig. 6 a switching equivalent circuit of the BLDC hub motor having the multiphase (i.e., 3-phase) is illustrated and in Fig. 5, a sequence diagram, distributing power control m-1 -phase excitation is illustrated. In Fig. 5 the excitation order is as follows: A-B → C-A → A-B → B-C

[50] That is, as shown in the equivalent circuit of FIG. 6, the distributing power control becomes possible during the control of the motor and thus a low voltage-high RPM, low- voltage-high torque BLDC hub motor becomes possible. In addition, a current load of each phase is lower than that of the conventional motor and thus the thermal generation rate is low, thereby increasing the reliability.

[51] Referring to FIG. 5, there is shown a timing of the switching signal of the driving unit 303. FIG. 5 shows an example of a switching signal for driving the 3-phase 16-poles BLDC hub motor.

[52] The switching signal must have the m-1-phase (m=2, 3, 4,—). For the 3-phase, two phases are driven and one phase must take a rest.

[53] The residence power of the motor is eliminated through the phase taking the rest phase and the rest section. A switching signal between the 7.5° and 15° makes two phases always turned on and one phase turned off when the motor rotates in sequence (A-phase is turned ON, a B -phase is turned ON, and a C-phase is turned OFF).

[54] That is, the conventional motor excites all of the phases but the motor of the present invention excites some of the phases. When comparing with the PWM control method for controlling an AC or DC motor, this switching principle maintains uniform torque by constantly supplying power in every section, thereby enabling the precise torque control. In addition, since there is no need provide a torque controller and a high quality algorithm, the control apparatus can be realized with less expense while generating the precise linear torque.

[55] The conventional motor control principle varies an amount of power supply in different section and thus it is impossible to uniformly control the torque. Therefore, the conventional motor control principle requires the high quality and high performance processor and algorithm.

[56] This causes the increase of the costs of the drive and motor. The motor constituted with the magnets can effectively drive and improves the efficiency and control performance only when it overcomes the magnetic force of the magnets.

[57] The motor of the present invention can easily overcome the magnetic force and effectively control the RPM by enabling the distributing power control that distributes and power by using the multi-phase parallel structure shown in FIG. 6.

[58] Referring to FIG. 6, there is shown connection 603 of the stator and rotor of the

BLDC hub motor having the multi-phase parallel structure in accordance with the embodiment. A 3-phase 16-poles motor is exemplarily illustrated. This motor is formed with an equivalent circuit (Bl, B2, Cl, and C2 are same as Al and A2) having parallel connection of one phase Al coil and one phase A2 coil. In addition, when varying a slot structure of the stator, an m-phase (m=2, 3, 4,—.) becomes possible. Each phase has an independent, parallel structure.

[59] The structure of the BLDC hub motor connects the coil of the stator and includes a shaft, a sensor plate, and the like. The rotor includes a magnet, a wheel, and an encoder plate.

[60] As shown in FIG. 7, a method of controlling a BLDC hub motor in accordance with an embodiment of the present invention includes turning a power source for a motor and a logic power source on (SlO), inputting an forward/reverse signal of the motor, an RPM signal of the motor, and a variable RPM command signal of the motor from the input unit to the controller 103 (S20), allowing the process unit of the controller 103 to convert the variable RPM command signal that is an analog signal into a digital signal using an A/D converter (S30), allowing the processor unit of the controller 103 to synchronize the digital signal with the sensor signal of the sensor unit 106 by comparing the digital signal with the sensor signal of the sensor unit 106 and to operate the synchronized signal (S40), outputting the operated signal to the driving unit 303 as the upper and lower end driving signals (S50), and controlling timings of the upper and lower driving signals using a circuit such as a latch such that a cycle of a waveform of the lower driving signal is longer than a cycle of a waveform of the upper end signal (S60), wherein the controlling of the timings uses a discontinuity phase excitation method having a rest section during the phase excitation.

[61] The method further includes allowing the driving unit 303 to output a signal for driving the motor driving H-bridge of the switching device unit 104 by amplifying the received output signal (S70), allowing the motor driving H-bridge of the switching device unit 104 to apply a driving signal to the motor in accordance with the driving signal from the driving unit 303 (S 80), allowing the motor driving H-bridge, when a driving current is applied, to rotate the motor and to detect the rotation (S90), determining if an RPM command value is 0 by comparing the sensor signal of the sensor unit 106 with the RPM command value of the input unit 102 (SlOO), and stopping, when the RPM command value is 0, the motor or, when the RPM command value is not 0, returning the process to the operation S30.

[62] Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure.

Claims

[1] A control apparatus for a brushless direct current hub motor, comprising: an input unit generating a forward/reverse RPM control command of the motor; a sensor unit detecting rotation of the motor; a controller outputting a motor driving signal by combining a motor rotational signal of the sensor unit with the RPM control command of the input unit; a switching device unit supplying a driving current to the motor by performing switching operation in accordance with the motor driving signal; and a brushless direct current hub motor rotating by the driving current, wherein the brushless direction current hub motor has a multi-phase independent parallel winding; and the controller drives the switching device unit such that a switching-on time of a lower end signal of the H-bridge is longer than a switching-on time of an upper end signal of the H-bridge to eliminate residence power of a motor coil.

[2] The control apparatus of claim 1, wherein the controller comprises a driving unit outputting a signal for driving the switching device unit in accordance with the motor driving signal.

[3] The control apparatus of one of claims 1 or 2, the controller performs a discontinuity phase excitation of the motor to eliminate the residence power of the motor coil.

[4] The control apparatus of claim 1, wherein the sensor unit is a photo interrupter sensor for detecting the rotation of the motor.

[5] A control method for a brushless direct current motor having a multi-phase independent parallel winding, comprising:

(a) receiving a forward/reverse signal of the motor, a variable RPM command signal of the motor, and an RPM signal of the motor;

(b) receiving and synchronizing the variable RPM command signal and the RPM signal of the motor;

(c) combining the synchronized signals and outputting a motor driving signal in accordance with the combined signals, wherein a switching-on time of a lower end signal of the motor driving signal is longer than a switching-on time of an upper end signal;

(d) rotating the motor using a current applied in accordance with the driving signal output;

(f) determining if the variable RPM command signal of the motor is 0 and stopping, when it is determined than the variable RPM command signal of the motor is 0, the motor. [6] The control method of claim 5, further comprising, before performing the receiving and synchronizing, converting the variable RPM command signal into a digital signal using an analog/digital converter. [7] The control method of claim 5, wherein the combining of the synchronized signals comprises performing discontinuity phase-excitation to eliminate residence power of a motor coil.