KR100327383B1 - Method for detecting rotor position of bldc motor - Google Patents

Abstract

Design the circuit to detect the rotor position according to the electromagnetic correlation of the BLDC motor and configure it outside the BLDC motor so that accurate rotor position detection can be performed regardless of the temperature / pressure condition according to the rotor operation. The present invention relates to a rotor position detection device of a BLDC motor, comprising: an inverter driver for supplying and driving a three-phase (u / v / w) power supply to a BLDC motor, a BLDC motor, and a 'u' phase power supply among three-phase power sources. A multiplier for multiplying the coil inductance (Ls) by the current, a first integrator for integrating the current flowing in the 'u' phase of the three-phase power supply and multiplying the coil resistance value, and an equivalent coil of each of the three-phase power supplies. Magnetic flux by adding the second integrator for integrating the voltage of the pseudo neutral point implemented by connecting the resistors Ru '/ Rv' / Rw ', the operation output of the second integrator and the inverted first integrator and multiplier With an adder that outputs a value And a zero detector for detecting the position of the rotor whose magnetic flux value is '0' and the microcomputer for detecting the rotor drive position by pulling the phase of the zero detector output by 90 °. Reliability can be improved.

Description

Rotor position detection device of BLC motor {METHOD FOR DETECTING ROTOR POSITION OF BLDC MOTOR}

The present invention relates to a brushless DC (BLDC) motor, and more particularly to a rotor position detection device of the BLDC motor.

In general, a BLDC motor forms a magnetic field and a rotor for transmitting torque to the outside, an amateur coil generating a torque by interaction with the electromagnetic field, and a stator core that forms a magnetic path at the same time as fixing the amateur coil. It is installed on the side or the upper side of the rotor and consists of a position detecting element such as a hall sensor for detecting the rotational position of the rotor.It has good torque characteristics at low speed and is small compared to other motors. It is mainly used in washing machines that require torque and require high speed and low torque when dehydrating.

In this case, as shown in FIG. 1, the BLDC motor 10 receives a three-phase power source (u / v / w) and has a coil having N pole or S pole magnetism and a N pole and S pole permanent magnet installed therein. It is configured to include a rotor that rotates according to the magnetism of, the hall sensor is installed to detect a position for driving the rotor, that is, the position of the polarity change, such as 'A' or 'B' point.

The hall sensor is installed on the side or the upper side of the internal rotor of the BLDC motor according to the prior art, and when the rotor rotates at high speed, the temperature and pressure inside the BLDC motor rise and accordingly There is a problem that the sensor is damaged and does not accurately perform the sensing operation.

Accordingly, the present invention has been made to solve the above-described problems, and designed a circuit for detecting the rotor position according to the electromagnetic correlation of the BLDC motor and configured the outside of the BLDC motor to the temperature according to the rotor operation It is an object of the present invention to provide a rotor position detection device of a BLDC motor capable of performing accurate rotor position detection regardless of a pressure condition.

1 is a view for explaining the rotor position detection of a BLDC motor according to the prior art

2 is an equivalent circuit diagram of a BLDC motor

3 is a view showing the configuration of a rotor position detection device of a BLDC motor according to the present invention;

4 is a view showing a detailed configuration of FIG.

Explanation of symbols for main parts of drawings

100: BLDC motor 200: inverter drive unit

300: multiplier 400, 500: integrator

600: adder 700: zero detection unit

800: micom

The present invention multiplies the coil inductance (Ls) by the current flowing in the 'u' phase of the three-phase power supply, the inverter drive unit for supplying and driving the three-phase (u / v / w) power to the BLDC motor, BLDC motor A multiplier for multiplying, a first integrator for integrating the current flowing in the 'u' phase of the three-phase power supply and multiplying the coil resistance value, and an equivalent resistance of the coil for each of the three-phase power supplies (Ru '/ Rv' / Rw). An adder for outputting a magnetic flux value by adding a second integrator for integrating the voltage of the pseudo neutral point implemented by connecting '), an arithmetic output of the second integrator, and an inverted first integrator and a multiplier, and outputting a magnetic flux value; And a microcomputer for detecting the rotor drive position by pulling the phase of the zero detector output by 90 ° and detecting the position of the rotor whose output magnetic flux value is '0'.

Prior to the detailed description of the present invention, first, the design principle of the circuit for detecting the drive position of the rotor will be described.

Since the driving position of the rotor to be detected in the present invention is a position at which the electromotive force induced by the motor coil becomes '0', the electromotive force (e ₀ ) is expressed by the expression with reference to the equivalent circuit diagram of the motor shown in FIG. Equation 1 is as follows.

Here, 'V' is a voltage applied to the motor coil, 'Ra' is a motor coil resistance, 'i' is a current flowing in the motor coil, and 'jwLs (Xs)' is an inductance of the motor coil.

Here, each variable according to Equation 1 described above is a value that cannot be measured in practice.

Therefore, integrating both sides of Equation 1 is expressed as Equation 2, which is an equation for the magnetic flux (φ) that links the rotor, and the variables included in Equation 2 are converted into values that can be measured. Shall be.

However, as a result of integrating both sides in Equation 2 'That is, the magnetic flux (φ) is 90 ° behind the sine value' e ₀ 'to actually obtain the cosine value, so obtain the magnetic flux according to Equation 2 and pull the phase 90 °, the rotor required in the present invention The principle is to detect the driving position.

Therefore, according to this principle, the present invention can be realized by designing a circuit for pulling the above-described equation (2) and its phase by 90 ° and by linking the two circuits together.

Next, the rotor position detection apparatus of the BLDC motor applied to the above-described principle will be described with reference to the accompanying drawings.

3 is a layout showing the configuration of a rotor position detection device of a BLDC motor according to the present invention, Figure 4 is a view showing a detailed configuration of FIG.

The rotor position detection apparatus of the BLDC motor according to the present invention is an inverter for supplying and driving three-phase (u / v / w) power to the BLDC motor 100 and the BLDC motor 100 as shown in FIG. 3. The driver 200 integrates a multiplier 300 for multiplying the coil inductance Ls by the current i flowing in the 'u' phase power among the three phase power supplies, and the current i flowing in the 'u' phase power. And a pseudo neutral point N 'implemented by connecting a first integrator 400 for multiplying the coil resistance Ra and an equivalent resistance Ru' / Rv '/ Rw' of each of the three-phase power supplies. The second integrator 500 for integrating the voltage V _N'G , the arithmetic output of the second integrator 500 and the inverted arithmetic output of the first integrator 400 and the multiplier 300 are finally added. An adder 600 for outputting a magnetic flux value, a zero detection unit 700 and a zero detection unit 700 for detecting a position of a rotor whose magnetic flux output from the adder 600 becomes '0' Pulling the phase of 90 ° is configured to include a microcomputer (800) for detecting a rotor driving position.

Referring to the configuration of the present invention in more detail as shown in Figure 4, the multiplier 300 receives the current (i) flowing through the motor coil to the inverting end (-) through the resistor (R1) and the non-inverting end (+) Is grounded and includes a first OP amplifier A1 having an output terminal connected to the inverting terminal (−) through a resistor R2.

In addition, the first integrator 400 receives a current i flowing in the motor coil through the resistor R4 and inputs the inverting terminal (-), and the non-inverting terminal (+) is grounded through the resistor R6. The resistor R5 and the capacitor C1 are connected in parallel with each other to form a second OP amplifier A2.

Subsequently, the second integrator 500 _{inputs the} pseudo neutral voltage V _N'G to the inverting terminal (-) through the capacitor C2 and the non-inverting terminal (+) is grounded through the resistor R8, and inverts the output terminal. A resistor R7 and a capacitor C3 are connected in parallel between the stages (-) to constitute a third OP amplifier A3.

In addition, the adder 600 has an inverting end through a resistor R9, a resistor R10, and a resistor R11 in which the outputs of the multiplier 300, the first integrator 400, and the second integrator 500 are connected in parallel. The non-inverting terminal (+) is input to (−) and is grounded through the resistor R12, and one end and the output terminal of the resistor R9 are constituted by a fourth OP amplifier A4 connected through the resistor R13.

In addition, the zero detector 700 includes a photo coupler (PC) supplied with + 5V power to the anode of the photodiode (PD) and the collector of the photo transistor (PT), and the output of the adder (600) at the base has a resistance (R14). And a cathode of the photodiode (PD) of the photocoupler (PC) is connected to the collector, and the emitter is grounded and composed of a transistor (Q1) connected with a resistor (R15) between the emitter and the base. The output line is drawn between the collector and the power supply terminal of the photo transistor PT and input to the microcomputer 800.

Referring to the operation of the rotor position detection device of the BLDC motor according to the present invention configured as described above are as follows.

According to an external operation command, the inverter driver 200 supplies three-phase power, and accordingly, the BLDC motor 100 starts driving.

Next, the multiplier 300 multiplies the current i flowing through the 'u' phase of the three-phase power by the coil inductance Ls. ', And the first integrator 400 multiplies the coil resistance Ra and performs integration at the same time. Outputs the second integrator 500 by integrating the pseudo neutral point voltage V _N'G Output '

The adder 600 adds the inverted output of the multiplier 300, the inverted output of the first integrator 400, and the output of the second integrator 500 to ' Ie outputs magnetic flux φ.

Subsequently, the zero point detection unit 700 crosses the magnetic flux by using the characteristic that the output changes when the output of the adder 600 transitions from 'high' to 'low' or 'low' to 'high'. A time point, that is, a time point when the magnetic flux becomes '0' is detected and a predetermined signal is output.

Here, as described above, the signal output from the zero point detection unit 700 is a time point at which the magnetic flux becomes '0', which is 90 ° behind the induced electromotive force (e ₀ ).

Therefore, the microcomputer 800 recognizes the rotor drive position signal by advancing the phase of the zero detection unit 700 by 90 ° and drives the BLDC motor accordingly.

The rotor position detection device of a BLDC motor according to the present invention uses a zero induced electromotive force at the time of driving the motor to design a circuit according to the electromagnetic relationship and install it outside the motor to achieve high speed rotation of the rotor. Regardless of the temperature / pressure condition, the accurate rotor drive position can be detected at all times, thereby improving the reliability of motor operation.

Claims (1)

BLDC motor, Inverter drive unit for supplying and driving three-phase (u / v / w) power to the BLDC motor, A multiplier for multiplying the coil inductance Ls by the current flowing in the 'u' phase power of the three-phase power source, A first integrator for integrating a current flowing in the 'u' phase power and multiplying a coil resistance value, A second integrator for integrating the voltage of the pseudo neutral point implemented by connecting the equivalent resistances Ru '/ Rv' / Rw 'of each of the three phase power supplies, An adder for adding a calculation output of the second integrator and an inverted calculation output of the first integrator and the multiplier to output a magnetic flux value; A zero point detector for detecting the position of the rotor whose magnetic flux value output from the adder is '0', And a microcomputer for detecting the rotor drive position by pulling the phase of the zero point detector 90 °.