JPS5852878Y2 - Transistor motor drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive circuit for a transistor motor that detects the rotational position of a permanent magnet rotor using a magnetic conversion element and switches and controls the current flowing through a drive coil of a stator.

The conventional transistor motor drive circuit uses three magnetic transducers MR1, MB2°MB2, as shown in Fig. 1, and detects the position of the permanent magnet rotor using the magnetic transducers MR1, MR2°MB2. ,・It is configured to obtain an output according to this detected position.

Then, the outputs of the magnetic transducer elements MR0, MR2, and MR3 are used as switching transistors Q and *Q, respectively.
29Q3 is turned on and off, and its output signal is sent to the corresponding commutator drive transistor Q4 * Q! l s
This is used as the control signal for Q6.

However, according to this circuit, the magnetic transducer M R,=MR
2. Since three MR3s are used, the output of each element becomes uneven due to rotor magnetization, variations in the elements, etc. Therefore, for example, as shown in FIG.
, L2. The phase of the terminal voltage of L3 deviates from the normal phase, causing a delay as shown in a and a lead as shown in b in the figure.

Even if a delay like b occurs, two or more amplifying transistors Q1-Q2-Qs are turned on at the same time, resulting in a decrease in efficiency. However, if a delay like a occurs, the switching transistor Q1゜Q2-
There is a decisive drawback as a starting circuit in that not even one Qs turns on, resulting in starting failure.

Therefore, in recent years, in order to eliminate this drawback, a differential switching circuit is constructed by connecting the emitters of three switching transistors in common, and a magnetic conversion element is connected to the base of each switching transistor, and the output of this magnetic conversion element is It is known to control the on/off state of a switching transistor, and control the drive transistor in accordance with the on/off state of the switching transistor to control the energization of the drive coil.

Since one of the switching transistors in the drive circuit is always in an on state, the drawback of starting failure can be solved.

However, in the case of the above two drive circuits, three magnetic transducers are used, so the structure for magnetically shielding each magnetic transducer is complicated, and the magnetic transducer is expensive, so the cost is high. It had the disadvantage of being expensive.

The present invention has been devised in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a drive circuit for a transistor motor that is simple in structure and inexpensive.

The transistor motor drive circuit of the present invention connects the emitters of a plurality of switching transistors in common, connects a thermal resistance element to the base of one of the switching transistors, and connects the base of the other switching transistor to the rotor position. A magnetic conversion element is connected to detect the temperature, and the temperature coefficients of this magnetic conversion element and the thermal resistance element are set to be approximately equal, and the output of each switching transistor is used to control on/off of the corresponding drive transistor. This device is characterized in that when the drive transistor is turned on, a drive coil connected in series to the drive transistor is energized and driven.

Next, one embodiment of the present invention will be described based on FIGS. 3 and 4.

This embodiment is of a three-phase, half-wave type, and uses, for example, a Hall element as the magnetic transducer.

The two magnetic transducers MR, MR2 have an electrical angle of 120
The thermistor Th as a thermal resistance element is placed at a location where the temperature rises to the same extent as the magnetic transducer elements MR1 and MR2.

The magnetic transducer MR, the resistor R2, and the magnetic transducer MR2 and the resistor R6 are connected in series to the power supply terminal (
+Vcc) (-Vcc), and the base of a switching transistor Q+-Q2 as a differential switching circuit is connected to the intermediate point thereof.

The emitters of switching transistors Q1-Q2 are
They are connected to the power supply terminal (-Vcc) through a common resistor R1, and their respective collectors are connected to the power supply terminal (+Vcc) through resistors R3 and R4, respectively, and directly to the drive transistors Q4 and Qs. It is connected to the base.

A resistor R7 and the thermistor Th are connected in series between the power supply terminals (+Vcc) (-Vcc),
The connection point is connected to the base of switching transistor Q3.

The emitter of this switching transistor Q3 is connected to the emitter of the switching transistor Qt-Q2, and its collector is connected to the power supply terminal (
+Vcc) and reaches the base of the drive transistor Q6.

The drive transistors Q4, Qa-Qa are
These are connected between the power supply terminals (+Vcc) and (-Vcc) in series with drive coils L1*L2 and L3, respectively.

Next, the operation of this embodiment will be explained.

When power is supplied to the circuit to drive the motor, the potentials vA, vB, and Vo at the positions indicated by the arrows in the circuit change as shown in FIG.

However, once the temperature of the thermistor Th is determined, the potential Vo shows a constant value.

The signals of potentials vA, vB, and vo are respectively applied to the switching transistors Q1. Q2. It is input to the base of Q3, but those amplification transistors Q1s Q29Q3
Their emitters are grounded through a common resistor R1, so that their switching transistors Q1. Q2
．． Q3 works differentially.

Here, the signal potentials vA and vB change with a phase difference of 120°, and the other signal potentials Vo remain constant.

If we compare the three here, their potentials VA and vB. The highest values of Vo are alternated by 120 degrees.

Therefore, the drive transistor Q4 t Qa 1Q6 is
The on state is sequentially and continuously repeated every 1200 phases.

Furthermore, since the switching operation is differential, the switching of the drive transistors Q4, Q5sQ6 is always performed reliably.

Now, since this circuit part can be separated from the motor part, it is not affected by the heat generated by the motor part.

However, the position detection element, that is, the magnetic transducer element MR1, MR
2 must be placed inside the motor, so it is immediately affected by the temperature rise in the motor section.

In particular, large-capacity motors are easily affected by the heat.

The magnetic transducer elements MR, MR2 used here are:
Since its resistance value decreases as the temperature rises, the potential v
The curves of A and ■ are generally downward due to a decrease in the level.

However, since the thermistor Th is used as another element, the potential Vo also decreases as the temperature increases.

Here, magnetic transducer elements MR1゜MR2 and thermistor T
If the temperature coefficient of h is set almost the same, the transistor Q
7. Q2. The switching operation of Q3 will be performed accurately even if the temperature fluctuates, even if the position shifts by 12 plates.

In other words, the two magnetic transducers MR11MR2 and the 18 thermistors Th can perform the same operation as the conventional drive circuit using three magnetic transducers.

In the case of thermistor Th, magnetic transducer elements MR1,
Unlike MR2, it does not require a magnetic shield and is inexpensive, so the structure is simpler and cheaper than conventional drive circuits.

According to the present invention, one of the conventionally used magnetic transducer elements is
Since the magnetic shield is replaced with a non-resistance element, magnetic shielding is easy and costs can be reduced, so the structure is simple and can be manufactured at low cost.

[Brief explanation of drawings]

Figure 1 is a drive circuit diagram of a conventional transistor motor, Figure 2 is a drive circuit diagram of a conventional transistor motor.
3 is a circuit diagram showing an embodiment of the transistor motor drive circuit of the present invention, and FIG. 4 is a diagram showing its operating characteristics. Ql, Q2. Q3...Switching transistor, Q4. Q6. Q6...drive transistor,
MRl. Mn2...magnetic conversion element, Th...thermal resistance element thermistor, "1?"2 t"3...
...Drive coil.

Claims (1)

[Scope of utility model registration request] Connecting the emitters of the plurality of switching transistors in common, connecting a thermal resistance element to the base of the one switching transistor, and connecting a magnetic conversion element for detecting the position of the rotor to the base of the other switching transistor, Furthermore, the temperature coefficients of this magnetic conversion element and the above-mentioned thermal resistance element are set to be approximately equal, and the output of each switching transistor is used to control the on/off of the corresponding drive transistor, and when these drive transistors are on, they are connected in series to this drive transistor. A drive circuit for a transistor motor, characterized in that a drive coil connected to a drive coil is energized and driven.