KR100292527B1 - A method of sinusoidal current control for brushless dc motor - Google Patents

Abstract

The present invention relates to a sinusoidal current control method of a BCD motor. In the related art, when a drive logic applied to a motor is controlled by a fixed pulse width modulation method when a BLC motor is controlled, a distorted current waveform is generated, thereby causing torque ripple of the motor. This causes vibration noise and decreases the output efficiency of the motor. Accordingly, the present invention provides a method for performing a method of initializing RAM and variables; Detecting a initial position of the rotor from the hall sensor, and initializing and enabling a timer in the microcomputer; A third step of initially forcing the motor to the desired control logic from the position of the current rotor sensed in the second step; Determining whether the hall sensor value has been changed; If the value of the hall sensor has not been changed as a result of the determination in the fourth step, the process returns to the third step. If the value of the hall sensor is changed, the timer value T1 at that time is read from the RAM and the timer value T1 is changed. A fifth step of determining whether it is an overflow; If the timer value T1 is overflowed as a result of the determination in the fifth step, the process returns to the second step. If the timer value T1 is not an overflow, the timer value T1 read from the change of the hall sensor is read and stored in the RAM. And the compensation control angle ( Calculating a sixth step; It is determined whether to stop the driving of the motor and returns when the stop request is made. If there is no stop request, the motor returns to the desired control logic from the detected rotor position and then returns to the desired control logic. By minimizing the distortion, it is possible to improve the ripple of the torque, and also increase the torque by increasing the conduction angle of the switching element gate terminal, thereby improving the output efficiency of the motor.

Description

A METHOD OF SINUSOIDAL CURRENT CONTROL FOR BRUSHLESS DC MOTOR}

The present invention relates to a sinusoidal current control method of a BCD motor, and in particular, to improve the current waveform in a motor conduction angle control method for reducing vibration noise of a BLC motor, to improve the output efficiency of the motor. It relates to a sinusoidal current control method.

In general, the BCD motor control apparatus detects the counter electromotive force of the voltage supplied to the motor, as shown in FIG. 1 of the accompanying drawings, and displays three Hall sensors for each phase of the rotor of the motor 300. Detected by (Ha, Hb, Hc), and using the detected position information of the rotor to determine the rotational speed of the motor 300 according to the control signal (U +, V +, W +, U-, V-, W- A microcomputer (100) for outputting; Switched by the control signal (U +, V +, W +, U-, V-, W-) of the microcomputer 100 to the drive unit 200 to apply the alternating current of the desired average voltage and frequency to the motor 300 It is composed.

FIG. 2 is a detailed circuit diagram of the BCD motor 300, and includes six transistors which receive a predetermined control signal of the microcomputer 100 through the interface unit 500 and are subjected to conduction control accordingly. A driving unit 200 consisting of an inverter in which two transistors are connected in series, and an inverter of the two transistors connected in series of the driving unit 200 are connected to each common connection point and converted according to switching of the driving unit 200. It consists of a BCD motor 300 consisting of a stator to which the three-phase power is applied and a rotor operated by a rotor magnetic field of the stator. The operation of the conventional apparatus will be described with reference to FIGS. 1 and 2. .

First, the BCD motor 300 is a motor 300 that uses the characteristics of permanent magnets instead of brushes among brush motors, unlike induction motors. Hall sensors (Ha) Rotation by, Hb, Hc is always detected and the detected signal is applied to the microcomputer 100 as shown in FIGS. 3A, 3B, and 3C.

Then, the microcomputer 100 receives the detection signal to determine the rotational speed of the motor 300, and compares the determined rotational speed with a target speed set in advance of the program. Controlled by timing signals U +, V +, W +, U-, V-, and W- as shown in FIGS.

That is, the microcomputer 100 outputs a predetermined control signal through the interface unit 500 to enable the switching operation of the driving unit 600. The microcomputer 100 controls the counter electromotive force of the voltage supplied to the motor 300. After detecting the position of the rotor of the current motor 300, and using the detected position information of the rotor to determine the rotation speed of the motor 300, the determined rotation speed and the predetermined target speed in the program Compare and control the motor 300 to rotate at the target speed according to the comparison result.

In other words, six pulse waveforms, which are fixedly generated by combining three Hall sensors Ha, Hb, and Hc, are transmitted to the driving unit 200, as shown in FIGS. By switching each of the three transistors, the power supplied to each phase of the motor 300 is controlled to drive the motor 300.

At this time, the waveform of the current flowing in the motor 300 is as shown in FIG.

However, in the conventional technology operating as described above, when the driving logic applied to the BCD motor is used in the fixed pulse width modulation method, a distorted current waveform is generated, causing torque ripple of the motor, thereby causing vibration noise. In addition, there was a problem in reducing the output efficiency of the motor.

Accordingly, an object of the present invention is to provide a sine wave current control method of a BCD motor to improve the current waveform to improve the output efficiency of the motor.

1 is a block diagram showing the configuration of a general BCD motor control apparatus.

2 is a detailed circuit diagram of the BCD motor control apparatus

3 is a control timing diagram for switching a driving unit in FIG.

Fig. 4 is a diagram of current waveforms flowing in a motor in Fig. 1;

Figure 5 is a flow chart of the operation of the sinusoidal current control method of the present invention.

Figure 6 is a block diagram showing the configuration of the BCD motor control apparatus to which the present invention is applied.

FIG. 7 is a control timing diagram for switching a driving unit in FIG. 6; FIG.

Fig. 8 is a waveform diagram of a control pattern for pulse width modulation in Fig. 6;

9 is a waveform diagram of current between terminals in FIG. 6;

FIG. 10 is a measured waveform diagram of current between terminals in FIG. 6; FIG.

Figure 11 shows the logic for calculating position information for pulse width modulation in Figure 6;

12 is a cross-sectional view of a direct drive type washing machine to which the present invention is applied.

***** Description of the symbols for the main parts of the drawings *****

100: microcomputer 200: drive unit

300: motor 400: power supply

The present invention for achieving the above object comprises a first step of initializing the RAM and the variable; Detecting a initial position of the rotor from the hall sensor, and initializing and enabling a timer in the microcomputer; A third step of initially forcing the motor to the desired control logic from the position of the current rotor sensed in the second step; Determining whether the hall sensor value has been changed; If the value of the hall sensor has not been changed as a result of the determination in the fourth step, the process returns to the third step. If the value of the hall sensor is changed, the timer value T1 at that time is read from the RAM and the timer value T1 is changed. A fifth step of determining whether it is an overflow; If the timer value T1 is overflowed as a result of the determination in the fifth step, the process returns to the second step. If the timer value T1 is not an overflow, the timer value T1 read from the change of the hall sensor is read and stored in the RAM. And the compensation control angle ( Calculating a sixth step; It is determined by the determination of whether to stop the driving of the motor to return when the stop request, characterized in that the seventh step of controlling and returning the motor from the position of the detected rotor to the desired control logic, characterized in that performed.

Hereinafter, the operation and effects of the sinusoidal current control method of the BCD motor according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a flowchart illustrating a sinusoidal current control method of a BCD motor according to the present invention. Detecting the initial position of the rotor from the hall sensors (Ha, Hb, Hc), initializing a timer in the microcomputer (100), and enabling it; A third step of forcibly driving the motor 300 to the desired control logic from the position of the current rotor sensed in the second step; A fourth step of determining whether the values of the hall sensors (Ha, Hb, Hc) have been changed; If the value of the hall sensors Ha, Hb and Hc has not been changed as a result of the determination in the fourth step, the controller returns to the third step, and if the values of the hall sensors Ha, Hb and Hc are changed, the timer value at that time Reading (T1) from the RAM to determine whether the timer value T1 overflows; When the timer value T1 is overflowed as a result of the determination in the fifth step, the controller returns to the second step. When the timer value T1 is not overflowed, the timer value read from the change of the hall sensors Ha, Hb, and Hc ( Read T1) into RAM and save the compensation control angle (T1) from the timer value. Calculating a sixth step; The seventh step of determining whether to stop the driving of the motor 300 is returned when a stop request is requested, and if there is no stop request, the motor 300 is controlled and returned from the detected position of the rotor to a desired control logic.

Figure 6 is a circuit diagram showing a configuration for the BCD motor control apparatus to which the present invention is applied, as shown in the general configuration is the same as the conventional, except that the conventional control system 300 can generate a current in two phases Differently from the fact that the current is generated in three phases, the operation of the present invention will be described.

First of all, in order to rotate the synchronous motor, the DC motor must sense the position of the rotor composed of the magnet of the NS pole and control the current direction (+,-) flowing in the stator appropriately for the NS pole. do.

At this time, the current direction control is configured as the control logic as shown in FIG. 7 to control the switching of the driving unit 200 to generate a sinusoidal current, as shown in FIG. 7. Controlling the switching with the N +) generates a complete sinusoidal current waveform as shown in FIG.

That is, as shown in FIG. 8, the currents applied to U, V, and W of each phase such that the voltage (current) pattern between terminals is UV = SINwt, WU = SIN (wt-120) and VW = SIN (wt-240), respectively. Change it to apply.

In other words, in order to ensure that the line voltage waveform is always a sine wave as shown in FIG. By applying the same angle extended by each phase to each phase, the current waveform corresponding to the voltage between each terminal becomes a complete sine wave current waveform as shown in Fig. 9, and Fig. 10 is a waveform diagram of the actual measured current.

Here, in order to form the control logic as shown in FIG. 7, the combined values and pulse widths of the control timings of the hall sensors Ha, Hb, Hc and the switching elements U +, U-, V +, V-, W +, W- are shown. The pulse width modulation value at the time of modulation switching is compensated for as shown in FIG. It is stored as a look-up table in the RAM of the microcomputer 100 to have a).

At this time, six switching elements from the Hall sensors Ha, Hb, and Hc are respectively set to 180+. Compensation control angle, which is an unknown control angle, is used to control switching by as much as 180 degrees or more. ) Needs to be calculated.

Here, the compensation control angle ( ) Operates the timer in the microcomputer 100 and obtains the timer value as the interval value T1 whenever the Hall sensors Ha, Hb, and Hc change as shown in FIG. 11, and stores it in the RAM. ) To 60 degrees.

Then, the value stored in the RAM is obtained as a distance value T1 of each section (six sections within 360 degrees), that is, the control compensation angle ( ) Is T1 Obtained from the formula

At this time, the control compensation angle calculated from the timer value T1 stored in the register and the timer value T1 ( ) Is stored in RAM whenever the logic of Hall sensors Ha and Hb changes.

Thereafter, the conduction angle of the gate of each switching element (180+ ) Is checked each time by the combination of position information, and the motor is operated while repeatedly performing the control timing of FIG. 7 stored in the RAM.

12 is a cross-sectional view of a direct drive type washing machine to which the present invention is applied.

As described in detail above, the present invention can improve the ripple of the torque by minimizing the distortion of the sinusoidal current waveform, and also increases the torque by increasing the conduction angle of the switching element gate stage, thereby improving the output efficiency of the motor. It can be effected.

Claims (2)

Initializing the RAM and the variable; Detecting a initial position of the rotor from the hall sensor, and initializing and enabling a timer in the microcomputer; A third step of initially forcing the motor to the desired control logic from the position of the current rotor sensed in the second step; Determining whether the hall sensor value has been changed; If the value of the hall sensor has not been changed as a result of the determination in the fourth step, the process returns to the third step. If the value of the hall sensor is changed, the timer value T1 at that time is read from the RAM and the timer value T1 is changed. A fifth step of determining whether it is an overflow; If the timer value T1 is overflowed as a result of the determination in the fifth step, the process returns to the second step. If the timer value T1 is not an overflow, the timer value T1 read from the change of the hall sensor is read and stored in the RAM. And the compensation control angle ( Calculating a sixth step; It is determined whether to stop the driving of the motor and returns when the stop request is performed. If there is no stop request, the BLC motor performs the seventh step of controlling and returning the motor from the detected rotor position to the desired control logic. Sinusoidal current control method The method of claim 1, wherein the compensation control angle ( ) Is a sinusoidal current control method of the BCD motor, characterized in that 60 degrees.