JPH04222489A - Speed controller for dc brushless motor - Google Patents

Abstract

PURPOSE:To provide a speed controller for a DC brushless motor of simple constitution and not requiring cost. CONSTITUTION:When it is a normal rotation command, a driving signal is distributed to each transistor, FET, of an inverter transistor circuit 7 from a distributing circuit 4, and a synchronous motor 8 rotates normally. The signal sending from a comparator 3 to the distributing circuit 4 is inhibited by a reverse rotation detector 5. When it changes into a reverse rotation command, a forward reverse rotation changeover circuit 6 is changed over on the side of reverse rotation, and the logic condition from the position detector 1 is inverted and the synchronous motor 8 is inverted. When the speed of the synchronous motor 8 exceeds the speed of the speed command, the output of the comparator 3 is inverted, and the distributing circuit distributes signals that turn the transistors UP, VP, and WP on and that the FETs UN, VN, and WN off, and power generation is braked. When the motor speed drops below the speed of the speed command, the distributing circuit 4 distributes a driving signal to the inverter transistor circuit 7 again. This way, power generation is braked intermittently in driving of reverse rotation, and the synchronous motor is controlled into the speed in accord with the speed command.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to speed control of DC brushless motors, and more particularly to speed control of DC brushless motors suitable for squid fishing machines, railroad crossing barriers, and the like.

0002

2. Description of the Related Art Recently, from the viewpoint of labor saving and automation, demands on the speed-torque characteristics of the drive motors used have been diversifying.

That is, the speed-torque characteristics of the motor may be required to have different characteristics during forward rotation and reverse rotation, and as a drive motor for squid fishing machines, railroad crossing barriers, etc., lowering operation should be gentle and raising operation should be gentle. needs to be fast.

The speed-torque characteristics of the motor for this purpose are:
As shown in Fig. 6, during the raising operation, for example, the forward rotation drive (
It has an inversely proportional speed-torque characteristic as shown in (a), and a constant speed characteristic as shown in (b) as a reverse drive during the lowering operation.

Motors with such drive characteristics include motors with brakes and inverter drive motors controlled by PWM (pulse width modulation).

[0006]

However, these motors have complicated auxiliary devices and control circuits, and there is room for improvement in terms of device miniaturization and cost performance.

The present invention has been made in view of these problems, and an object of the present invention is to provide a speed control device for a DC brushless motor that has a simple configuration and is inexpensive.

[0008]

Means for Solving the Problems In the present invention, in order to achieve the above object, a speed control device for a DC brushless motor is configured as shown in (1) and (2) below.

(1) An inverter circuit for energizing a synchronous motor, in which arms each consisting of anti-parallel connected diodes and transistors are bridge-connected, a position detector for detecting the rotor position of the synchronous motor, and the position detector a distribution circuit that distributes a drive signal to the transistors of each arm of the inverter transistor circuit according to the output of the inverter transistor circuit; an F-V converter that generates a voltage according to the output frequency of the position detector; A speed control device for a DC brushless motor, comprising a comparator that compares an output with a speed command signal and sends a comparison output to the distribution circuit, the distribution circuit further comprising: A speed control device for a DC brushless motor, which distributes an on signal to the transistors on each arm on the positive or negative side of an inverter transistor circuit and an off signal to the transistors on each arm on the negative or positive side of an inverter transistor circuit.

(2) A forward/reverse switching circuit that inverts the logic state of a signal sent from the position detector to the distribution circuit in response to a forward/reverse command; The speed control device for a DC brushless motor according to (1) above, further comprising a forward/reverse rotation detection circuit that prohibits the comparison output from being sent from the comparator to the distribution circuit.

[0011]

[Operation] With the configurations (1) and (2) above, when the speed of the synchronous motor exceeds the speed of the speed command signal, the transistors in each arm on the positive or negative side of the inverter transistor circuit are turned on, and the transistors on the opposite side are turned on. The transistors in each arm of are turned off to apply a dynamic brake to the synchronous motor, and when the speed of the synchronous motor falls below the speed specified by the speed command signal, the synchronous motor is energized again, and by repeating this process, the speed of the synchronous motor is adjusted to the speed command. Control the speed accordingly.

In the configuration (2) above, the logic state of the signal to the distribution circuit is reversed in response to the forward/reverse command, the synchronous motor is rotated forward or reversed, and the distribution from the comparator is performed during forward or reverse rotation. Prohibits comparison output from being sent to the circuit, and prohibits speed control from being performed during forward or reverse rotation.

[0013]

[Examples] The present invention will be explained in detail below using examples. FIG. 1 shows a "DC for level crossing barrier" which is an embodiment of the present invention.
1 is a block diagram showing the configuration of a brushless motor speed control device. In the figure, a position detector 1 uses a Hall IC, and the frequency of this output signal is F-V.
The converter 2 converts it into a voltage signal. The output voltage of the F-V converter 2 is compared with the speed command voltage in a comparator 3, and the output signal of the comparator 3 is sent to the distribution circuit 4 via the reverse rotation detection circuit 5. In addition, F-
The V converter 2, comparator 3, and reverse rotation detector 5 constitute a speed control section 9. Vcc is the positive pole side of the DC power supply, and the negative pole side is the ground.

The inverter transistor circuit 7 is composed of a three-phase transistor bridge, each arm on the positive side of the bridge uses an NPN transistor, and each arm on the negative side uses an FET (field effect transistor). All transistors have diodes connected in antiparallel.

The forward/reverse switching circuit 6 inverts the logic state of the output of the position detector 1 in response to a forward/reverse command, and shifts the input phase of each arm transistor of the inverter transistor circuit 7 by 180°. .

The reversal detector 5 that inputs forward/reverse commands is
The output signal of the converter 3 is sent to the distribution circuit 4 only during reverse rotation.

The distribution circuit 4 distributes a 120° width drive pulse to the drive circuits of the six transistors UP to WN constituting the inverter transistor circuit 7.

Assuming that a forward rotation command is now issued, the distribution circuit 4 causes a pair of transistors in the positive and negative arms of the inverter transistor circuit 7 to conduct, for example, UP and VN are brought into conduction, and then UP and WN are brought into conduction. conducts, then VP and W
A drive signal is sequentially distributed to each transistor so that N becomes conductive (see FIG. 5), and the synchronous motor 8 rotates forward in the normal mode.

The speed-torque characteristic of the motor in this case is such that the speed and torque are in an inversely proportional relationship, as shown in FIG. 6(a).

When a reverse command is issued, the forward/reverse switching circuit 6 inverts the logic state of the output of the position detector 1, and thereby each transistor UP to WN of the inverter transistor circuit 7
The conduction order changes. For example, if a reverse command is input while UP and VN are conducting, UP and VN are turned off, VP and UN are turned on, and
Subsequently, WP and UN become conductive, the direction of the current in the stator coil of the synchronous motor 8 is reversed, the direction of the torque applied to the rotor is reversed, and the rotor of the synchronous motor 8 begins to rotate in reverse.

[0021] The reverse speed increases, and the F-V converter 2
When the output voltage becomes equal to or higher than the speed command voltage, the output of the comparator 3 is inverted to "H". The reverse rotation detector 5 outputs the output of the comparator 3 to the distribution circuit 4 since the reverse rotation command has been received.

As a result, the transistor drive signal sent from the distribution circuit 4 is transmitted to the inverter transistor circuit 7.
Turn on the transistors UP, VP, and WP on each arm on the positive side, and turn on the FETs UN, VN, and WN on each arm on the negative side.
This is the signal to turn off the switch.

As a result, although the driving current for a normal motor no longer flows through the synchronous motor 8, a dynamic brake is applied due to the back electromotive force generated by the rotation of the rotor, and the synchronous motor 8 is rapidly decelerated. When the speed decreases and the output of the F-V converter 2 falls below the voltage of the speed command, the output of the comparator 3 becomes "L", the dynamic brake is released, and the synchronous motor 8 is driven again to increase the speed. in this way,
Since the electromagnetic brake is applied intermittently during driving, the speed of the synchronous motor 8 is controlled to be constant according to the speed command, and the speed of the synchronous motor 8 is controlled to be constant according to the speed command.
), the speed-torque characteristics are obtained.

Next, this embodiment will be explained with reference to detailed drawings. 2 is a detailed diagram of the position detector 1 and the forward/reverse switching circuit 6, FIG. 3 is a detailed diagram of the distribution circuit 4 and the inverter circuit 7, and FIG.
2 is a detailed diagram of the speed control section 9. FIG. 3 is placed on the right side of FIG. 2, and FIG. 4 is placed below FIG. 2, and are connected to each other at parts 1 to 2 to form one circuit diagram. FIG. 5 is an explanatory diagram of the operation of this embodiment. Portions with the same symbols as those in FIG. 1 in FIGS. 2 to 5 are corresponding portions.

In FIG. 2, 1-1, 1-2, and 1-3 are Hall ICs arranged in the stator of the synchronous motor 8.
This is a module that integrates a Hall element and its amplifier. The outputs of the Hall ICs 1-1, 1-2, and 1-3 are as shown in FIG. 5(a).

6-1 is a non-inverter array consisting of three non-inverters connected to the same power source;
-2 is an inverter array consisting of three inverters connected to the same power source. Arrays 6-1 and 6-2 are
Power is selectively supplied through lines (1) and (2), and the array to which power is supplied supplies signals to resistors 6-3, 6-4, and 6-5. FIG. 2 shows a state when power is being supplied to the array 6-1, that is, a state where the forward/reverse rotation switching circuit 6 is switched to the forward rotation side.

In FIG. 3, 4-1 to 4-6 provide drive signals for providing a conduction period of 120° to the transistors UP to WN of each arm of the Ihanter circuit 7 based on the output of the forward/reverse switching circuit 6. It is a NAND gate to form. The output of each gate is as shown in FIG. 5(b) when power is supplied to the non-inverter array 6-1, and as shown in FIG. 5(b) when power is supplied to the inverter array 6-2. c). Note that FIG. 3 shows a state in which power is being supplied to the non-inverter array 6-1, that is, a state in which a normal rotation command is issued.

Reference numerals 4-8, 4-9, and 4-10 are analog switches which are turned on when the input of the inverter 4-7 is "L" and turned off when the input is "H".

4-17 is an amplifier array that supplies base current to each of the NPN transistors UP, VP, and WP on the positive side arm, and 8 is a synchronous motor.

In FIG. 4, 2-1, 2-2, and 2-3 are NAND gates that form pulses with a frequency three times that of the output of the position detector 1, and 2-4 is a NAND gate 2. This is an F-V converter that converts the outputs of -1, 2-2, and 2-3 into voltages proportional to their frequencies.

3-1 is a comparator, and variable resistor 2-
The speed command voltage set in step 6 is compared with the output voltage of the F-V converter 2-4 via the buffer 2-5, and when the rotational speed of the synchronous motor 8 exceeds the speed of the speed command, the signal becomes "L".
is output, and when it does not exceed, outputs "H".

5-4 is a manual switch that is switched depending on whether the synchronous motor 8 is placed on the left or right side of a cut-off rod (not shown); in the illustrated position, the synchronous motor 8 rotates forward when the cut-off rod is raised, and rotates forward when the cut-off rod is lowered. Reverse speed control is performed. When the manual switch 5-4 is reversed, the synchronous motor 8 rotates in the reverse direction when the switch is turned up, and rotates forward when it is turned down, thereby controlling the speed.

[0033] 5-6 is a switch or relay that commands raising/lowering of the cutoff rod.

The operation will be explained below with reference to FIGS. 2 to 6. Suppose now that the command voltage VCC is applied to the "rise" of the switch 5-6. Power is supplied to the non-inverter array 6-1 of the forward/reverse switching circuit 6 via the manual switch 5-4, the forward/reverse switching circuit 6 is switched to the forward rotation side, and the transistors UP of each arm of the inverter transistor circuit 7 ~
The drive signal shown in FIG. 5(b) is supplied to WN, and the synchronous motor 8 rotates normally with its original characteristics as shown in FIG. 6(a), and the cutoff rod is raised rapidly.

At this time, the inverter 5- of the reverse rotation detector 5
Since the input of the inverter 4-7 is "H", the input of the inverter 4-7 is "L" regardless of the output of the comparator 3-1, and the dynamic brake is not applied.

[0036] When the switch 5-6 "falls", the command voltage VC
When C is applied, power is supplied to the inverter array 6-2 of the forward/reverse switching circuit 6 via the manual switch 5-4, the circuit 6 is switched to the reverse side, and the NAND gates 4-1 to 4 of the distribution circuit 4 The logic state of the signal to 4-6 is reversed, and the drive signals to the transistors UP to WN of each arm of the inverter transistor circuit 7 change from (b) to (c) in FIG. 5, and the torque applied to the rotor of the synchronous motor 8 increases. The direction of is reversed and reversed.

At this time, the inverter 5- of the reverse rotation detector 5
Since the input of comparator 3-1 is "L", the output of comparator 3-1 is sent to distribution circuit 4 via inverter 3-2.

The speed of the synchronous motor 8 increases, and the variable resistor 2
If the command speed set in -6 is exceeded, comparator 3 -
The output of 1 is inverted from "H" to "L". Therefore, the output of inverter 3-2 becomes "H", and inverter 4-7
The input of gate 4-1 is "H" and the output is "L".
1, 4-12, 4-13 block the drive signals to the FETs UN, VN, and WN of each arm on the negative side of the inverter circuit 7, and the analog switches 4-8, 4-9, and 4
-10 is turned off and the transistors on each arm on the positive side are UP,
An on signal is supplied to VP and WP, and a dynamic brake is applied to the synchronous motor 8.

When the speed of the synchronous motor 8 falls below the speed command, the output of the comparator 3-1 becomes "H", the output of the inverter 3-2 becomes "L", and the synchronous motor 8 returns to the reverse driving state. Become.

[0040] In this way, the electric power braking is applied intermittently during reverse driving, and the cutoff rod descends at a substantially constant speed with the characteristics shown in FIG. 6(b).

When the manual switch 5-4 is switched to the reverse position, the rotational speed is controlled to a constant speed in forward rotation, and the motor rotates rapidly in reverse rotation with its original characteristics.

Note that the inverter transistor circuit 7 is
Although the configuration is a mixture of bipolar transistors and FETs, it may also be configured using only bipolar transistors or only FETs. Although bipolar transistors require control power, their voltage drop is smaller than that of FETs, making them suitable for dynamic braking.

[0043] In the embodiment, the speed is controlled to be constant during reverse rotation or forward rotation, but the present invention is not limited to this, and the same method can be used to control the speed during either forward or reverse rotation. This can be carried out by controlling the speed to be constant.

[0044] Furthermore, the speed can be controlled to be constant during forward or reverse rotation without providing a forward/reverse switching circuit.

Furthermore, the speed is not limited to being controlled to be constant, but the speed may be controlled in accordance with a changing speed command.

[0046]

[Effects of the Invention] As explained above, according to the present invention,
Speed control can be performed at low cost with a simple configuration without requiring complicated auxiliary devices or circuit configurations such as conventional brake-equipped motors or PWM-controlled inverter-driven motors.

[Brief explanation of the drawing]

[Figure 1] Block diagram of the embodiment

[Figure 2] Detailed diagram of the position detector and forward/reverse switching circuit

[Figure 3] Detailed diagram of distribution circuit and inverter transistor circuit

[Figure 4] Detailed diagram of speed control section

[Figure 5] Operation explanatory diagram of the embodiment

[Figure 6] Explanatory diagram of speed-torque characteristics

[Explanation of symbols]

1 Position detector 2 F-V converter 3 Comparator 4 Distribution circuit 7 Inverter transistor circuit 8 Synchronous motor

Claims (2)

[Claims] 1. An inverter transistor circuit for energizing a synchronous motor, in which each arm consisting of an antiparallel-connected diode and a transistor is bridge-connected, a position detector for detecting a rotor position of the synchronous motor, and the position detector a distribution circuit that distributes a drive signal to the transistors in each arm of the inverter transistor circuit according to the output of the inverter transistor circuit;
F that generates a voltage according to the output frequency of the position detector
-V converter; and a comparator that compares the output of the F-V converter with a speed command signal and sends a comparison output to the distribution circuit, the distribution circuit comprising: Furthermore, according to the comparison output of the comparator, an on signal is distributed to each transistor on the positive side or negative side of the inverter transistor circuit, and an off signal is distributed to each transistor on the negative side or positive side of the arm. Features: Speed control device for DC brushless motor. 2. A forward/reverse switching circuit that inverts the logic state of a signal sent from a position detector to a distribution circuit in response to a forward/reverse command; and a forward/reverse switch circuit for reversing the logic state of a signal sent from a position detector to a distribution circuit in response to a forward/reverse command; 2. The speed control device for a DC brushless motor according to claim 1, further comprising a forward/reverse detection circuit that prohibits the comparison output from being sent from the comparator to the distribution circuit.