KR940007151B1 - Arrangement for starting brushless dc motor - Google Patents

Abstract

The 3-phase brushless DC motor driving circuit without a rotator position detector includes a plurality of resistors connected to rotator driving coils, first to third comparators for respectively comparing terminal voltages detected by the resistors with a reference voltage, first to third driving transistors for turning on the rotator driving coils, and first to third switching transistors for cutting off current of the rotator driving coils, thereby achieving low power consumption.

Description

3-phase BLDC motor driving circuit without rotor position detector

1 is a three-phase BLCD motor driving circuit diagram without a rotor position detector according to the present invention.

2 is a connection state diagram for obtaining voltages of respective phases in FIG.

3 is an operational state waveform diagram of a three-phase BLCD motor driving circuit without a rotor position detector according to the present invention, (a) is a terminal voltage waveform diagram of each phase, and (b) is a voltage of each phase detected by the terminal voltage. (C) is the output state of the comparator according to the reference voltage and the voltage of each phase, (d) is the operating state of the transistor which conducts current to each phase.

* Explanation of symbols for main parts of the drawings

1 to 3: Comparators Q1 to Q3: Rotor driving transistor

Q4 to Q6 switching transistor Vs: power supply voltage

La to Lc: rotor drive coils R11 to R14, R21 to R24, R31 to R34, R4 to R9: resistance

Va to Vc: Terminal voltage V: Reference voltage

The present invention relates to a three-phase BLDC motor driving circuit without a rotor position detector. In particular, a three-phase BLDC without a rotor position detector suitable for a place where the motor is miniaturized by removing the rotor position detector. It relates to a motor drive circuit.

In the conventional three-phase BLDC motor driving circuit, a Hall (Hal1) element or a resolver (Resolver) is used to detect the position of the rotor (permanent magnet) necessary for motor rotation in a three-phase BLDC motor, but the Hall element is used. In this case, the structure of the motor is complicated, and the manufacturing process is complicated, and the size of the large size is required due to the hall element output line (needed more than six) and power is required.

Accordingly, the present invention is a three-phase BLDC motor drive circuit that eliminates Hall elements required for position detection to solve the above-mentioned disadvantages, and thus, a three-phase BLDC motor drive circuit without a rotor position detector for later integrated circuit (IC). It will be described in detail with reference to the accompanying drawings the circuit configuration thereof.

In FIG. 1, the power supply voltage Vs is connected to the collector terminal of the rotor driving transistors Q1 to Q3 that are emitter grounded through the rotor driving coils La to Lc, and the rotor driving coils La to The connection terminals of the series resistors R11 and R12 (R21 and R22) (R31 and R32) connected in parallel to Lc are passed through the resistors R13, R23 and R33, respectively, for each electron driving transistor Q3 and Q2. It is connected to the resistors R14 (R24) and R34 connected to the collector terminal of (Q1), and is connected to the "-" input terminal of the comparators 3, 2 and 1, and the reference voltage VR is the resistor R6. Connected to the collector terminal of the switching transistors Q6, Q4 and Q5 that are connected to the " + " inputs of the comparators 3, 1 and 2 via R5 and R4, (3) The outputs of (1) and (2) are connected to the base end of the rotor driving transistors Q3, Q1 and Q2 via resistors R9, R7 and R8, and at the same time switch transistor Q5. Looking at the operating state and effect of the circuit configuration as a configuration connected to the base end of (Q4) (Q6) As follows.

In Fig. 1, the three-phase Y-connected unipolar (Unipolar) means that the rotor (permanent magnet) of the drive type BLDC motor is sine wave magnetized. Terminal voltages Va to Vc are as shown in FIG.

In other words, in the armature voltage equation for the phase in Figure 2 (a),

Since the reactance is very small in the case of the small motor in Equation (1), the terminal voltage is not affected by the rotor drive coil La.

In this way, it can be seen that the terminal voltage Va is represented by the counter electromotive force superimposed on the power supply voltage Vs. In addition, 12 ^o energized 3-phase BLDC motors are most efficient when each phase (A, B, C) is energized in the “Ta, Tb, Tc” section of Fig. 3 (a) because of the torque characteristics. It is very important to detect "t1, t2, t3 ..." in FIG. 3 (a) using the acid terminal voltages Va, Vb, Vc.

Therefore, in the present invention, the "t1, t2, t3 ..." point is detected by using the terminal voltages Va, Vb, and Vc of the motor. The method of FIG. Derived from the voltages Va, Vb, Vc, the power supply voltage Vs, and the resistance, the moment at which the voltage of the terminals Vxa, Vxb, Vxc becomes less than the power supply voltage Vs is detected.

As an example, the process of detecting the "Ta" section will be described.

therefore

Accordingly, the voltage waveforms of the terminals Vxa, Vxb, and Vxc become as shown in FIG. 3 (b), and the voltage waveforms of the terminals as shown in FIG. 1 correspond to the "-" of the comparators 1, 2 and 3 in FIG. The points "t1, t2, t3 ..." are detected in comparison with the reference voltage VR which becomes an input and becomes a "+" input.

That is, when the voltage t of the terminal VXa becomes smaller than the reference voltage VR in FIG. 3 (b), the output of the comparator 1 becomes high as shown in FIG. &Quot; ON " to turn on the rotor driving transistor Q1 and the switching transistor Q6, thereby turning on the rotor driving coil La and at the same time turning the " + " input of the comparator 3 into a " low " state. This turns off the rotor drive transistor Q3 which is already conducting.

Thereafter, when the voltage of the terminal voltage VXb reaches a position t2 at which the voltage of the terminal voltage VXb becomes smaller than the reference voltage VR, the output of the comparator 2 becomes "high" to switch the switching transistor Q4 of the rotor driving transistor Q2. Turn on the rotor drive coil Lb and at the same time turn the + input of the comparator 1 to the low state to turn off the rotor drive transistor Q1 that is already conducting. To cut off the current flowing through the rotor drive coil La.

In addition, when the voltage of the terminal voltage VXC reaches a position t3 that is smaller than the reference voltage RR, the output of the comparator 3 becomes "high", thereby driving the rotor driving transistor Q3 and the switching transistor Q5. Turn on the rotor drive coil Lc and at the same time turn the " + " input of the comparator 2 " low to " off " Cut off the current flowing in the rotor drive coil (Lb).

Therefore, in FIG. 1, the time that current flows to the rotor drive coils La to Lc is the time that the rotor drive transistors Q1, Q2, and Q3 conduct as shown in FIG. Ta) (Tb) (Tc) to operate as the most efficient three-phase BLDC motor driving circuit.

As described above, the three-phase BLDC motor driving circuit without the rotor detector according to the present invention eliminates the rotor position detector, thereby miniaturizing and reducing the power of the three-phase BLDC motor. Only by performing the position detection signal, it is advantageous to make the integrated circuit, and the position detection sensitivity is very excellent, and the effect of making the fast sound is excellent.

Claims (1)

The resistors R11 to R14, R21 to R24, R31 to R34 interconnected to the rotor drive coils La, Lb, and Lc to detect the energizing switching point of each phase, and the terminal voltage Vxa, Vxb, Vxc) and rotor driving coil La (Lb) according to the outputs of the comparators (1) (2) (3) and the comparators (1) (2) (3) comparing the comparison voltage (V _R ). Rotor drive transistors Q1 (Q2) Q3 conducting (Lc) and rotor drive transistors Q3 (A3) which are in conduction in accordance with the outputs of the comparators (1) (2) (3) ( A rotor comprising switching transistors Q6, Q4 and Q5 which cut off current of the rotor drive coils Lc, La and Lb which are already flowing by " off " 3-phase BLDC motor driving circuit without position detector.

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