JPS62281701A - Speed control unit for electric rolling stock - Google Patents

Abstract

PURPOSE:To allow an electric rolling stock to control the speed in the wide dynamic range, by controlling it with full wave conduction in low speed and high torque running and with half wave conduction in high speed and low torque running. CONSTITUTION:Armature windings 1-3 of a three-phase brushless DC motor 20 and a half wave conduction circuit and a full wave conduction circuit both supplying power to those windings are provided side by side. By manual operation by an operator of a rolling stock and automatic operation based on the detection of the torque and speed of motor, the speed control of an electric rolling stock is carried out in selectively changing over respectively through a control circuit 12 with half wave conduction by transistors 4, 5, 6 and 10 in low speed running and with full wave conduction by transistors 4-9 in high speed running. In this way, the motor can be driven in well high efficiency in the low speed limits so that the effectual speed control may be performed at fully wide range.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention Industrial Field of Application This invention relates to the speed of industrial electric vehicles such as electric vehicles and electric motorcycles for general road use and forklifts that use a motor as a driving power source. The present invention relates to a control device, and more particularly to a speed control device based on switching the energization method of an electric vehicle using a three-phase brushless DC motor as a driving power source.

BACKGROUND ART Conventionally, various electric vehicles using a motor as a driving power source belong to the public domain (for example, Utility Model Application Publication No. 49-132546, Utility Model Application Publication No. 5).
0-147354, etc.).

Normally, the speed control of electric vehicles, electric motorcycles, and other electric vehicles that use a motor as a driving power source is: ■ Voltage v control method that changes the voltage applied to the motor in large or small steps; ■ A transmission between the motor and the wheels. This is generally done using either the installed transmission control method. For rough speed control, a transmission control method using gear shift is adopted.
Furthermore, a voltage control method using pedal operation is used for detailed speed control to complement this.

The reason for this is that motors have low efficiency when high torque is required at low speeds, such as when starting a vehicle, and on the other hand, their efficiency improves as the required torque decreases at high speeds, such as when driving at high speeds. This is because in the low speed range, using a transmission can prevent a drop in efficiency.

When the above-mentioned voltage control method and transmission control method are used together for the speed control of a point-of-sight electric vehicle, which the present invention aims to solve, firstly, the structure of the electric vehicle becomes complicated, and it also becomes larger and heavier. become

Furthermore, there are problems in that the driving operation becomes complicated and the efficiency inevitably decreases due to the loss caused in the transmission.

On the other hand, it is possible to manufacture and put into practical use a motor with increased efficiency in the low speed range by increasing the field strength of the motor, etc., but this motor also has a smaller maximum speed, which makes it difficult to control the transmission. Since it is necessary to expand the dynamic range of speed by using both methods, the same problems as mentioned above arise.

Purpose Therefore, the purpose of the present invention is to provide an electric vehicle that does not require the adoption of a transmission control system, can drive a motor with sufficiently high efficiency in a low speed range, and can perform speed control over a sufficiently wide range for practical use. An object of the present invention is to provide a speed control device.

Means to solve problems As a means to solve the problems of the above-mentioned conventional technology.

The speed control device for an electric vehicle according to the present invention, as shown in the embodiment in the drawings, is a speed control device for an electric vehicle using a three-phase brushless DC motor as a driving power source, and includes: an electric motor of a three-phase brushless DC motor 2o; Child winding 1.2.
3, and a half-wave energization circuit and an aftereffect energization circuit to supply power to these.

The control circuit 12 selectively switches half-wave energization during low-speed driving and full-wave energization during high-speed driving, either manually by the vehicle driver or automatically based on detection of motor torque and speed. The configuration is designed to control the speed of electric vehicles.

In addition, as a specific embodiment, half wave 60° and 90°
The current-carrying circuit consists of three-phase armature windings 1, 2, .
3 and switching transistors 4, 5, and 6 for supplying power thereto are respectively connected, and a transistor 10 that performs a switching operation in synchronization with the transistors 4 to 6 is connected to the neutral point of the star-shaped connection. (Figure 3).

Further, the aftereffect 60° energizing circuit connects the three-phase electric machine prewinding i1, 2.3, which is also connected in a star shape, and the switching transistors 4, 5, 6 that supply power thereto, respectively. Transistors 7, 8, 9 which perform switching operations in synchronization with transistors 4, 5, 6 are connected to the emitters of transistors 4, 5, 6 (FIG. 3).

Further, the full-wave 90' energizing circuit connects the star-connected three-phase TL armature winding 2.3 and the switching transistor 4°5.6 that supplies power to it, respectively, Transistors 7.8.9 that perform switching operations in synchronization with the transistors 4.5.6 are connected to the emitters of the transistors 4.5.6, and the power supply battery 11 is connected to +V, O, and -V. A relay switch 14 that can be separated into two parts and can conduct electricity in both directions between its 0 point and the neutral point of the armature winding connected in a star shape.
(Fig. 5).

Function First, a three-phase brushless DC motor is a three-phase synchronous motor with a rotor on the armature side, as shown in Figure 1, which is a conceptual diagram of an outer rotor type three-phase brushless DC motor 20. A DC motor is equipped with a position sensor 21, and the timing of the current flowing through the armature windings of each phase is changed based on the position signal from the position sensor 21.

In FIG. 1, the rotor on the outer periphery is formed by arranging four permanent magnets 22 each having a size obtained by dividing the circumference into four equal parts, with the polarities S and N alternated.

The armature is an inner stator, and a position sensor 21, such as a Hall element, is attached to the end of three armature windings 1, 2.3 equally spaced at 120 degrees. This position sensor 21 detects the north and south poles of the permanent magnet 22 and performs two pairs of on and off (opening and closing) operations while the rotor rotates once.

FIG. 2A shows the output of the position sensor 21 for each phase. Since one same-position sensor 21 is attached to each armature winding, the output of the position sensor 21 is three in total.

Further, FIG. 2B-H shows the timing of the current flowing through each armature winding 1, 2.3 of the three-phase brushless DC motor 20. Incidentally, the case where current flows only in the positive direction through each armature winding is called half-wave energization, and the case where current flows in both positive and negative directions is called aftereffect energization. Also, changing the flow direction every 60' per rotation angle is called 60° energization, and changing the flow direction every 90° is called 90° energization.

The maximum number of revolutions that this motor can rotate under the same applied voltage is half-wave 9 when 1 is the case of half-wave 60° energization.
0' when energized is 1/1.5. The speed gradually decreases to 1/2 when the full wave is energized at 60° and to 1/3 when the aftereffect is energized at 90°.

On the other hand, the efficiency of the motor 20 improves in an inverse ratio to the above rotation speed. Therefore, at low speeds, the full wave 90
'The motor is rotated by energization, and as the speed increases, the energization method is changed to full wave 60' energization - half wave 90° energization - half wave 60°
It is only necessary to switch to energization, and then the dynamic range of speed control will be wide and the motor 20 will be rotated with high efficiency.

Because of the operating characteristics of the three-phase brushless DC motor 2o, as described above, the driver of an electric vehicle must perform manual switching operations when driving at low speeds, or detect the relationship between the motor rotation speed and the maximum torque at that time. automatically, the control circuit 12
A full-wave energization circuit is selected through , so-called full-wave energization is performed, and the motor 20 is rotated normally at low speed and large torque with high efficiency. Also, when running at maximum speed based on the relationship between power supply voltage and required torque, if you select a half-wave energization circuit and perform so-called half-wave energization, the maximum speed can be doubled without increasing the speed. It will come.

Embodiment Next, a first embodiment of the present invention shown in FIG. 3 will be described, particularly a speed control device having a configuration capable of half-wave 60° and 90° energization and full-wave 60° energization.

In the figure, reference numerals 1, 2, and 3 indicate three-phase armature windings of a three-phase brushless DC motor 20, which is a driving power source for an electric vehicle, and these are connected in a star shape.

In the figure, 4.5.6 is the three-phase armature winding 1 of the DC motor.
, 2.3, each collector is connected to the anode of the DC power supply 11 for power supply, and the emitter is connected to each armature winding 1.
, 2.3. Also, the base is pedal 13
The control circuit 12 is connected to the control circuit 12 which controls the voltage applied to the remoter 20 by the operation of:Afg.

Next, reference numeral 10 in the figure is a transistor which also constitutes a half-wave conduction circuit and performs switching operations of opening and closing in synchronization with the transistors 4, 5, and 6, and its collector is connected to the armature winding 1, which is connected in a star shape. ? .

3, its emitter is connected to the cathode of the DC power supply 11, and its base is connected to the control circuit 12.

During half-wave energization, the transistor 10 is always conductive, and the transistors 4, 10.5, 10,
Groups 6 and 10 are synchronized switching (opening and closing) in this order.
When the operation is performed, the current supplied by the DC power supply 11 becomes conductive to the armature winding 1.2.3 of each phase at the timing shown in FIG.
0' energization is performed, and the motor is efficiently rotated in the normal direction at high speeds. Switching between half-wave 60° energization and half-wave 90° energization depends on how the output of the position sensor 21 is taken.

Next, 7.8.9 in the figure is a transistor that constitutes a full-wave current-carrying circuit and performs a switching operation in synchronization with the transistors 4 and 5.6, and the collector of each transistor is the emitter of the transistors 4 and 5.6. The emitter side is connected to the cathode of the DC power supply 11, and the base is connected to the control circuit 1.
2 is connected.

Therefore, when switching from the above half-wave energization to the after-wave energization,
The transistor 10 is always off, and the pairs of transistors 4 and 8, 5 and 9, and 6 and 7 are connected to the control circuit 1, respectively.
Switching operations are performed in this order through 2.

The timing at which each element becomes conductive is the same as in FIG. The full wave 60' flows from 1 to 1 at the timing shown in the second diagram.
Power is applied and the motor has high torque in the low speed range.

Rotates forward with high efficiency.

By the way, the control circuit 12 has the functions of (1) switching each transistor 4-1o on and off according to the timing shown in FIG.
3. Adjust the current flowing through the circuit.

The former function (2) is performed by appropriately timing the outputs of the position sensor 21. For example, Figure 2B
In order to turn on and off at the timing, the output of the position sensor 21a and the reverse output of the position sensor 21b may be ANDed.

The function of the latter (2) is to switch the bases at high speed, since the method of adjusting the base voltage of each transistor 4 to 10 has a large loss, and the duty ratio of the switching is applied to the armature windings 1 to 3. This is done by utilizing the fact that it is proportional to the average voltage, that is, by chopping or pulse width control. More specifically, the armature winding 1 at the timing shown in FIG. 2B is controlled by the magnitudes of avA and b@ in the rectangular wave pulse, as shown in FIG. The average applied voltage is determined by the ratio of the a width to the b width.

Therefore, increasing the depression of the accelerator 13 attached to the control circuit 12 means increasing the value of the a width with respect to the b width of the rectangular wave pulse shown in FIG. 4 above. A rectangular wave pulse for such control can be created by first creating a rectangular wave pulse with a constant frequency using an astable multivibrator, and then using this rectangular wave as a trigger to operate a monostable multivibrator. All that is required is to change the time constant of the pibrator with respect to the depression angle of the accelerator.

Next, voltage and current control will be described. As mentioned above, changing the pulse widths a and b of the rectangular wave by the control circuit 12 means changing the average voltage applied to the armature windings 1 to 3. Therefore, the control circuit 12 changes the voltage This means that you are controlling the The relationship between the applied voltage (2), the rotational speed (n), and the current (I) of the motor 20 is expressed as V=Kn+IR. is a constant specific to the motor, and R is the resistance of the armature winding. From the above formula, if you change ■, the work will change,
Furthermore, the relationship between current flow and torque is T=KI/2π, which is proportional to current.

The above-mentioned switching between the half-wave energizing circuit and the full-wave energizing circuit for the passing motor is performed through the control circuit 12, but the switching is done by the driver of the electric vehicle by feeling the running speed of the vehicle or by actually measuring it with a meter. This can be done manually or automatically by detecting the torque and rotational speed of the motor.

By the way, a concrete method for automatic switching is, for example, to test in advance the relationship between the motor rotation speed during full-wave energization and the maximum torque at that time. When it is detected that the value has been reached, the switch will be made to half-wave energization. Incidentally, since the torque and current of the motor have a 1:1 relationship as shown in the above equation, the measurement of torque can be replaced by the measurement of the supplied current.

Second Embodiment Next, FIG. 5 shows a speed control device configured to allow half-wave energization and full-wave 90' energization.

Its basic circuit configuration is the same as the first embodiment shown in FIG. It is characterized by a configuration in which a switch 14 that can conduct bidirectional current supply like a relay is connected between the neutral point of the star-shaped connections 1 to 3.

In other words, when switching to full wave 90'.

Switch 14 becomes conductive, transistor 4.5.6 becomes conductive at the same timing as in FIG. 2C, and transistor 7.
8.9 conduct in opposite phase to the transistors 4 and 5.6, respectively, so that the current supplied by the DC power supply 11 to the armature windings 1.2.3 of each phase is as shown in FIG. 2E. The conduction state occurs at the right timing, that is, the aftereffect 90' is energized, and the motor is efficiently rotated in the normal direction even in a low speed range.

The effects of the present invention are as described in detail in conjunction with the embodiments, and the speed control device for an electric vehicle according to the present invention achieves high efficiency by full-wave energization during low-speed, high-torque running, and In the case of high-speed, low-torque running that is difficult to achieve with wave energization, switching to half-wave energization allows speed control with a wide dynamic range, and there is no need to employ a transmission control method.

[Brief explanation of drawings]

Figure 1 is a conceptual diagram of a three-phase brushless DC motor, Figure 2A is a diagram of the position sensor, and Figures 2B to E are waveforms showing the timing of current flow during half-wave energization and after-wave energization. 3 is a circuit diagram showing a speed control device for an electric vehicle according to the present invention, FIG. 4 is an explanatory diagram showing square wave control, and FIG. 5 shows a second embodiment of the invention. FIG.

Claims (1)

[Scope of Claims] [1] In a speed control device for an electric vehicle using a three-phase brushless DC motor as a driving power source, armature windings (1) (2) ( 3) is provided with a half-wave energization circuit and a full-wave energization circuit to supply power to the motor (20), and selectively switches between half-wave energization and full-wave energization to the motor (20) through the control circuit (12) to control the speed. A speed control device for an electric vehicle, characterized by having a configuration for controlling the speed. [2] Three-phase armature winding with star connection (1) (2) (
3) and switching transistors (4), (5), and (6) that supply power thereto are respectively connected, and the neutral point of the star-shaped connection is connected to the transistor (4).
The electric vehicle according to claim 1, characterized in that a transistor (10) that performs switching in synchronization with (6) is connected to constitute a half-wave 60° and 90° energization circuit. speed control device. [3] Three-phase armature winding with star connection (1) (2) (
3) and switching transistors (4), (5), and (6) that supply power thereto are connected, respectively, and a transistor (7) that performs switching in synchronization with the transistors (4, 5, and 6) is connected. ) (8) and (9) are connected to the emitters of the transistors (4), (5), and (6), respectively, to form a full-wave 60° energization circuit. [4] Three-phase armature winding with star connection (1) (2) (
3) and switching transistors (4), (5), and (6) that supply power thereto are connected, respectively, and a transistor (7) that performs switching in synchronization with the transistors (4, 5, and 6) is connected. )(8) and (9) are connected to the emitters of the transistors (4), (5), and (6), respectively, and the power supply battery (11) is connected to +V, O
, -V, and connect a relay switch (14) that can conduct electricity in both directions between the O point and the neutral point of the star-connected armature winding. A speed control device for an electric vehicle, characterized by comprising an energizing circuit.