JP3230757B2 - Three-phase DC brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase DC brushless motor in which a switching element of an inverter section is controlled based on a rotor magnetic pole position to switch the current and the phase of an armature winding.

[0002]

2. Description of the Related Art A conventional three-phase DC brushless motor has a configuration shown in FIG. In FIG.
0 is a DC power supply, 12 is an inverter unit composed of a transistor three-phase bridge circuit, 14 is a rotor, 16 (16a, 1
6b, 16c) are three-phase armature windings serving as stators.
The rotor is a claw-pole or comb-shaped massive rotor having a built-in permanent magnet, and serves as a field.

[0003] The inverter unit 12 includes a transistor T _r1, T _r2, T _r3 as three input-side switching element connected to the + side of the power supply 10, the power supply 10 - is connected to the side three output transistor T _r4 as side switching element, T _r5, have a T _r6. Each transistor T _r1 ~T _r6
Have anti-parallel flywheeling diodes D ₁ to
D ₅ is connected.

[0004] transistor T _r1 and T _r4 paired, T _r2 and T _r5, the connection point of the T _r3 and T _r6 are three-phase armature winding 16a~
16c is connected to one end. Each winding 16a-16c
Are connected to each other to form a star-connected armature winding 16 after all.

Reference numeral 18 denotes a rotor magnetic pole position detector, which includes a permanent magnet plate 20 directly connected to the rotor 14, three magnetic sensors 22 disposed at equal intervals so as to surround the permanent magnet plate 20, and outputs of the sensors 22. And a distributor 24 that determines the magnetic pole position of the rotor 14 based on the

[0006] 26 denotes a control unit, based on a signal indicating the rotor pole position distributor 24 outputs, as well as selectively turn on and off the transistor T _r1 through T _r3, transistor T based on the speed command select one of the _r4 ~T _r6 chopping control. Here, the difference (V ₁ −V) = V ₂ between the speed command 1V ₁ supplied from an external device and the speed signal V fed back from the control unit 26 is input to the control unit 26 as a speed command 2V _2. You.

[0007] The control unit 26 includes an input-side transistor T _r1 through T _r3 by the driver 28, 30, separately controlled and an output-side transistor T _r4 through T _r6. That input side transistor T _r1 through T _r3 is on as is within a predetermined rotor magnetic pole position is held in the ON or OFF state
Controlled off. Output-side transistor T _r4 through T _r6 is such that a duty ratio corresponding to the speed command V _3, for example, chopping control by PWM (pulse width control) scheme.

[0008] transistor T _r1 through T _r6 are here on-off control or chopping control, the change in order by changing the rotor magnetic pole position is a matter of course. As a result, the armature winding 16 generates a rotating magnetic field to rotate the rotor 14.

[0009]

Problems of the Prior Art In the motor configured as described above, there is a possibility that the external force is applied to the rotor 14 to forcibly reverse the rotation. For example, when this motor is used for driving a blower fan of an external unit of an air conditioner, the wind of the outside air drives the fan in the reverse direction to reverse the motor. By this reverse rotation, the motor functions as a generator, and generates an induced voltage of the opposite polarity in the armature winding 16.

[0010] When the transistor T _r4 through T _r6 of the side to be chopping control at this time is in a state close to all off or off, for example, when the transistor T _r1 is ON, the current i ₁ in winding 16a is by induced voltage flows , This current i ₁
The current flows back to the diodes D ₂ and D ₃ while being divided into the currents i ₂ and i ₃ of the windings 16b and 16c.

[0011] The on-off control by the transistor T _r1 ~
This is because _Tr3 is controlled so as to turn on sequentially in synchronization with the rotor magnetic pole position so that the ON periods do not overlap. When the induced voltage is large, there is a risk of destroying the diode D ₁ to D ₃ or transistor T _r1 through T _r3.

The currents i ₁ , i ₂ , i
When the transistor T _r1 is turned off when _{the 3} is flowing,
At the moment of the turning off, the current corresponding to the current i ₁ is generated by the induction component of the winding 16 through the diode D ₄ to the power supply 10.
Will flow from the negative electrode of the regenerative energy by the coil 16 is discharged through the diode D _4. Matato La
Njisuta T _r4 through T _r6 is chopping control, but operation
During the transistor T _r4 ~T _r6 of (in the chopping operation)
Off between as the T _r1 through T _r3 and D ₁ to D ₃ and the winding 1
Current circulates in 6. Oh but one of the T _r4 ~T _r6 is
At the moment of the current, a part of this current (for example , one of the currents i ₂ and i ₃ )
Transistor T _r4 ~T _r6 noise part) are out of the on
Re or (e.g. T _r5, T _r6) through the other D ₄ to D ₆ Noise
(For example, D ₄ ), and when it is turned off at this time,
Due to the induction component of the armature winding, the current is
Power supply 1 through any of D _{1 to} D ₃ (for example, D ₂ , D ₃ )
0 and the other D _{4 to} D ₆ (for example, D ₄ )
The current returning to winding 16 through
Will be issued. As a result, the voltage between both poles of the battery 10 sharply increases,
It could destroy the transistor T _r1 through T _r6 and diodes D ₁ to D ₆ is generated.

[0013]

[0008] The present invention has been made in view of such circumstances, the input and output of the inverter section
ON / OFF control of either switching element
When the other switching element is controlled by chopping
Another object of the present invention is to provide a three-phase DC brushless motor that can prevent a switching element and the like of an inverter from being damaged when the motor is reversed by an external force.

[0014]

According to the present invention, an object of the present invention is to provide an inverter unit in which input and output switching elements are connected in a three-phase bridge, a rotor magnetic pole position detector, and a rotor magnetic pole. Input side and output corresponding to position
ON / OFF control of either switching element
And the other switching element
A control unit for performing chopping control to obtain a tee ratio ,
In a three-phase DC brushless motor that switches the current and the phase of the armature winding based on the rotor magnetic pole position,
The drive current supplied to the armature winding during normal rotation of the rotor is
Means for detecting means for detecting the induced current generated in the armature winding when a reverse rotation of the rotor due to an external force, the driving
The current exceeds the set value for more than the set time of the timer.
In other words , the three-phase DC brushless motor is provided with protection means for turning off all the switching elements when the induced current exceeds a set value.

[0015]

FIG. 1 is a block diagram of one embodiment of the present invention. In this figure, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will not be repeated.

[0016] the foregoing differs from Figure 2 in this figure, an input-side transistor T _r1 current detection resistor 50 to the collector of the through T _r3 to be on-off control, also the diode D ₁
A point connected respectively to the current detection resistor 52 in to D _3,
The protection means 54 for determining the magnitude of the current detected by the resistors 50 and 52 and outputting the stop signal S when the current is equal to or larger than a predetermined value is provided. Resistor 50 detects drive current
The resistor 52 detects the induced current at the time of reverse rotation.
It is a means to carry out.

The protection means 54 has a comparator for comparing the voltage drop at the resistors 50 and 52 with a set value set by a setter. When the voltage drop at each of the resistors 50 and 52 increases beyond a certain level, a stop signal is output. S is output. When the control unit 26 outputs the stop signal S,
All transistor T _r1 through T _r6 simultaneously outputs a signal to each driver 28, 30 to turn off. As a result all the transistors T _r1 through T _r6 completely turned off, the inverter unit 12 is protected.

In the current detection by the resistor 50, it is desirable to configure the protection means 54 so as not to output the stop signal S for a large current at the time of starting the motor. For this reason,
For example, a timer 56 for disabling the protection means 54 for a fixed time when the motor is started can be provided.

[0019] The present invention has been made to turn off all the transistors T _r1 through T _r6 when the induced current exceeds the set value, which the is the place was turned off only the transistor T _r1 ~ T _r3 input side The purpose of the term cannot be achieved. This is because when the control unit 26 outputs a signal to rotate in the forward direction based on the speed command V ₃ to the driver 30 is that the two electrodes voltage of the power source 10 increases rapidly. The reason is as follows.

[0020] Since one of the transistors T _r4 through T _r5 when this is chopping, for example if the transistor T _r4 are chopping current i ₁ this flows at the moment of ON at the instant of the next off It will be returned to the positive electrode of the battery 10 through the flywheel diode D _1. During this other winding 16b, 16c current i ₂ of
Since i ₃ flows out of the negative electrode of the power supply 10 via the diodes D ₅ and D ₆ , the voltage between both electrodes of the power supply 10 increases rapidly. Therefore could destroy the transistor T _r1 through T _r6 and diodes D ₁ to D ₆ is because occurs.

[0021] In the above embodiments also in the switching element <br/> transistor T _r1 through T _r6, but, transistor
The may be other elements, such as thyristors in place of the data is a matter of course.

[0022]

As described above, the present invention detects the induced current generated in the armature winding when the rotor reversely rotates due to an external force separately from the drive current, and this induced current exceeds a set value. Since all the switching elements are turned off, it is possible to prevent the switching elements and the like from being damaged due to the induced current at the time of reverse rotation, thereby protecting the inverter section. Also the drive power
If the flow exceeds the set value for a certain period of time, all
Since the switching element is turned off, the
Protection mechanism can be activated to prevent the motor from stopping.
You.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 DC power supply 12 Inverter part 14 Rotor 16 Armature winding 18 Rotor magnetic pole position detector 26 Control part 50 Resistance 52 as drive current detection means Resistance 52 as induced current detection means 54 Protection means

Continuation of the front page (56) References JP-A-63-240392 (JP, A) JP-A-1-129792 (JP, A) JP-A-63-206188 (JP, A) JP-A-63-154092 (JP) , A) JP-A-63-56190 (JP, A) JP-A-63-198523 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 6/12 H02H 7/097

Claims (2)

(57) [Claims] 1. An inverter section comprising input-side and output-side switching elements connected in a three-phase bridge, a rotor magnetic pole position detector, and an input side corresponding to a rotor magnetic pole position.
ON / OFF control of one of the switching elements and the output side, and the other switching element responds to the speed command
The armature and control unit, equipped with, in the three-phase DC brushless motor that switches the current and phase of the armature winding on the basis of the rotor magnetic pole position at the time of forward rotation of the rotor to chopping control so that the duty ratio Supply to winding
Means for detecting a drive current, means for detecting an induced current generated in the armature winding when the rotor reversely rotates due to external force , and setting of a timer when the drive current exceeds a set value.
A three-phase DC brushless motor, comprising: a protection unit that turns off all of the switching elements when the induced current continues for a predetermined time or more or when the induced current exceeds a set value. 2. The means for detecting a drive current includes an input side and an input side.
Between the power supply and the power supply
It is formed by a current detection resistor interposed between
The detecting means is connected to the one switching element.
The current through the flywheeling diode
3. The three-phase DC brass according to claim 1, wherein said three-phase DC brass is formed by a current detecting resistor.
Siles motor.