JP2002354603A - Backlash reduction control device for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure stop performance having no uncomfortable feeling by reducing a shock and noise caused by a backlash in an operation of an electromagnetic brake or the like, in an electric vehicle of a complete stop type that is stopped by applying a brake force by the electromagnetic brake or the like while gradually applying the brake force to a motor when the vehicle is stopped. SOLUTION: A control device is provided with: a motor control means that controls the drive amount and the dynamic braking amount of a wheel-drive motor 1; an electromagnetic brake control means that brake-stops the revolution of the motor 1 by actuating the electromagnetic brake 2 when a stop operation is performed; and a current detecting means that detects a fed current and a generated current of the motor 1 before the operation of the electromagnetic brake 2 and switches a stop means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle such as an electric wheelchair, and more particularly to a control device for decelerating and stopping the electric vehicle.

[0002]

2. Description of the Related Art In an electric vehicle, particularly an electric wheelchair, a motor drive circuit is switched to a closed circuit when an accelerator for controlling a traveling speed is operated to a neutral position, that is, in conjunction with a stop operation. Take a deceleration means to gradually increase the braking amount to decelerate, actuate the electromagnetic brake attached to the motor shaft before complete stop, take braking stop means such as fixing the motor shaft, and stop from the uphill condition It is configured to be able to stop without slippage due to its own weight even during operation. In this ascending state, the traveling load is large not only during acceleration but also during deceleration,
Since the gear of the motor shaft, which is the driving gear, constantly drives the driven gear group in the drive transmission path, there is no change in the gear contact state even in the gear group with a large backlash. No impact or noise is generated when the motor shaft is fixed. Also, in the downhill state, the driving gear constantly brakes the driven gear group, so that there is no change in the gear contact state as when stopping from the uphill state, and there is no impact or shock even when the motor shaft is fixed. No noise is generated. Also, when stopping from a high-speed running state on a flat road surface, the driving gear that previously had the driven gear group in the driving state is switched to the braking state. The tooth surfaces are separated from each other and the adjacent tooth surfaces are in contact with each other. However, a sufficient deceleration of the vehicle body requires a certain deceleration time by the deceleration means. Is completed. That is, since the change of the gear contact state is completed in a state where the motor shaft and the drive side gear have not been fixed by the electromagnetic brake yet, no impact or noise is generated when the motor shaft is fixed by the electromagnetic brake. I have. However, when stopping from a very low speed running state on a flat ground, the above-described deceleration time is extremely short, and the motor shaft is fixed by the electromagnetic brake earlier than the completion of the change of the gear contact state, that is, the driving side gear is in the fixed state. In contrast, the gear tooth surfaces that have been in contact with each other are separated due to the backlash driven from the vehicle body due to the inertia force of the vehicle weight, and the driven gear tooth surface collides with the tooth surface of the adjacent driving gear. For this reason, there is a case where a shock is generated to generate noise or stop with a sense of incongruity. For this reason, JP-A-8-29
As a means to reduce backlash in 6718 etc.,
There is disclosed a technique of sandwiching a mating gear with a driving gear.

[0003]

In the above technique, it is necessary to employ a member for reducing the backlash itself, and the load on the gear box tends to increase. An object of the present invention is to improve the above-mentioned drawbacks of the prior art, and to reduce a stop impact and noise caused by backlash during traveling at a low speed without using any additional members.

[0004]

A motor control means for controlling a driving amount and a power generation braking amount of a wheel driving motor 1 and an electromagnetic brake control for stopping the rotation of the motor 1 by operating an electromagnetic brake 2 at the time of a stop operation. Means, a current detection means for detecting a supply current and a generation current of the motor 1 and a motor rotation sensor 3 for detecting the number of rotations of the motor 1. When the supply current value or the generated current value of the motor 1 at the time when the rotation speed of the motor is controlled to be equal to or less than the set value exceeds the set value, the motor 1 is controlled by the motor control means. When the supply current value and the generated current value are both equal to or less than the set values, the electromagnetic brake is applied after a predetermined period of time. That performs the stop control motor 1 by 2, construction of an electric vehicle backlash reduction control apparatus characterized.

[0005]

When the vehicle is stopped on a hill or a high-speed running state on a flat ground, a relatively large supply current or a relatively large amount of power is generated even when the motor control means increases the amount of braking generated by the motor 1 immediately before the stop. When a current is generated, the current is detected by the current detecting means, and the driving of the motor 1 is stopped immediately and the motor 1 is stopped by the electromagnetic brake 2, so that the stopping can be performed without slipping due to its own weight. When the vehicle is stopped from a low-speed running state on a flat ground, only a small supply current and a generated current are generated. The detected current is detected by the current detection means, and the power generation braking is further performed for a predetermined time by the motor control means. During the time, the driving gear,
That is, in a state where the gear of the motor shaft is not fixed by the electromagnetic brake 2, the gear tooth surfaces of the driven side gear group of the drive transmission path that have been in contact therewith are separated by backlash, and the adjacent tooth surfaces are in contact with each other. After the contact of the tooth surfaces of the driven gear group is switched to a state in which the drive gear is braked, the electromagnetic brake 2 stops the motor 1, that is, the drive gear is fixed. The stop with less noise can be performed.

[0006]

FIG. 1 is a block diagram showing a connection state of input means and control means, in which the present invention is applied to an electric wheelchair.
U and 7 are key switches, which are configured to be able to supply the current of the battery power supply to the control circuit and the drive circuit by connecting the key switch 7. Reference numeral 8 denotes a speed command signal generator, which is specifically constituted by a variable resistor that is rotationally adjusted by an accelerator lever, and outputs the output voltage to a CPU.
Input to 6. Note that the output voltage of the speed command signal generator 8 at the neutral corresponding position which is automatically reset when the accelerator lever is released is set to the stop command voltage. Reference numeral 9 denotes a forward / reverse changeover switch. By operating the switch 9, the forward relay 4 or the reverse relay 5 can be connected via the forward relay switch 10 or the reverse relay switch 11 to control the rotation direction of the motor 1. It is configured in. Reference numeral 12 denotes a main relay switch, which is excited by the power switch "on" operation of the key switch 7 to connect the main relay 13 to enable supply of battery current to the drive circuit.

Reference numeral 14 denotes a drive transistor whose gate is connected to a motor drive circuit 15. The drive transistor 14 outputs a command speed of the speed command signal generator 8 and an actual speed detected by a motor rotation sensor 3 to be described later. The operation is controlled by a drive pulse output from the CPU 6, and the motor 1 is supplied with a current and driven. Reference numeral 16 denotes a braking transistor, the gate side of which is similarly connected to the motor drive circuit 15, which is also controlled by a braking pulse output from the CPU 6, and gives the motor 1 a dynamic braking action. Also, both transistors 1
4 and 16 are connected in series, and incorporate therein diodes 14a and 16a which operate at the time of reverse bias. The drain side of the driving transistor 14 is connected to the +24 V power supply side, and the source side of the braking transistor 16 is connected to the ground side. The motor rotation sensor 3 is composed of a tachogen attached to a motor shaft, and is configured to be able to detect the number of rotations and the rotation direction of the motor 1 by detecting rotation pulse outputs at two locations around the motor shaft. Numeral 2 denotes an electromagnetic brake of negative operation, which is configured to release braking by energization during running, and to return by spring force to apply a braking force to the motor shaft during stopping. Reference numerals 17 and 18 denote transistors for electromagnetic brake two-stage amplification. 19 is a current detection circuit, 20 is a 5-row LED
, A battery meter comprising a motor temperature sensor,
22, a control circuit temperature sensor; and 23, an outside air temperature sensor.

Next, the operation at the time of starting and at the time of constant speed traveling will be described. When the accelerator operation is performed after the key switch 7 is turned on, the electromagnetic brake 2 is released, and the command voltage of the speed command signal generator 8 is input to the CPU 6 in accordance with the operation amount. A braking pulse is output, the driving transistor 14 is driven by the driving pulse, and the vehicle travels by applying a battery current to the motor 1. At the same time, the CPU
6, the actual traveling speed is calculated and compared with the command speed, and the feedback control is performed so that the vehicle travels at the command speed by changing the duty ratio, which is the ratio of the drive pulse, according to the difference. If the actual speed is higher than the commanded speed, a braking pulse is output from the CPU 6 in accordance with the difference in speed to drive the braking transistor 16 to suppress the speed by dynamic braking.

Next, the operation at the time of stopping the traveling will be described with reference to the flowchart shown in FIG. When the hand is released from the accelerator lever, it is automatically returned to the neutral position by the elastic force, a stop voltage is output from the speed command signal generator 8, and the normal deceleration control is performed until the speed becomes less than 0.5 km / h. In this normal deceleration control,
Based on the stop command from the speed command signal generator 8 described above, the CPU 6 outputs a slow stop control means for gradually reducing the drive pulse and conversely increasing the brake pulse, so that the electric vehicle is gradually decelerated.

When the speed is reduced to 0.5 km / h,
The supply current value and the generated current value to the motor 1 detected by the current detection circuit 19 are input to the CPU 6, and if at least one of the current values is a fixed small current value, for example, 2 A or more, the CPU 6 promptly outputs the minimum current value. And the braking pulse is output to the maximum, the energization to the electromagnetic brake 2 is cut off, the braking force is applied, the motor shaft is fixed, and the electric vehicle is reliably stopped.

The condition under which this function works is assumed to be a stoppage from a climbing state, a downhill state, or a high-speed running state on a flat ground. In the stop from the uphill state, the gear of the motor shaft, which is the drive side gear, constantly drives the driven side gear group of the drive transmission path. No impact or noise is generated when the motor shaft is fixed by the electromagnetic brake 2. or,
In a downhill condition, the driving gear constantly brakes the driven gear group, so there is no change in the gear contact state as when stopping from the uphill state, and there is no impact or noise even when the motor shaft is fixed. Does not occur. Since the motor shaft is fixed by the electromagnetic brake 2 before the vehicle speed completely becomes 0 km / h,
Even if there is a delay time or the like in the operation of the electromagnetic brake 2, a stop can be performed without slippage due to its own weight.

When stopping from a high-speed running state on a flat ground,
Since the driving gear that had been driving the driven gear group is switched to the braking state, the gear contact state fluctuates, so that the gear tooth surfaces that have been in contact so far are separated and the adjacent tooth surfaces are in contact. Normally, the above-described fluctuation of the gear contact state is completed while the above-described normal deceleration control is operating. That is, since the change in the gear contact state is completed in a state where the motor shaft and the driving gear have not been fixed by the electromagnetic brake 2 yet, when the motor shaft is fixed by the electromagnetic brake 2, no impact or noise is generated. Stop.

If the supply current value and the generated current value to the motor 1 input to the CPU 6 are both less than 2 A, the CPU 6 outputs the minimum drive pulse for a certain period of time, for example, 0.3 seconds, and sets the braking pulse to the maximum. Then, the power supply to the electromagnetic brake 2 is stopped, a braking force is applied to fix the motor shaft, and the electric vehicle is stopped. As a condition under which this action works, it is assumed that the vehicle is stopped from a low-speed running state on a flat ground, etc., but under this condition, the above-described normal deceleration control is not performed for an extremely short time. Although the fluctuation of the gear contact state as described above is not completed, the fluctuation of the gear contact state is completed during the above-described braking pulse output period of the fixed time, and when the motor shaft is fixed by the electromagnetic brake 2,
There is no impact or noise.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control circuit.

FIG. 2 is a flowchart.

[Explanation of symbols]

 1 motor 2 electromagnetic brake 3 motor rotation sensor

Claims (1)

[Claims] 1. A motor control means for controlling a driving amount and a power generation braking amount of a wheel driving motor (1), and an electromagnetic device for activating an electromagnetic brake (2) to stop rotation of the motor (1) at the time of a stop operation. In an electric vehicle including a brake control unit, a current detection unit for detecting a supply current and a generation current of the motor (1), and a motor rotation sensor (3) for detecting a rotation speed of the motor (1), the electric vehicle is linked to a stop operation. Motor (1)
If the supply current value or the generation current value of the motor (1) at the time when the rotation speed of the motor is controlled to be equal to or less than the set value is larger than the set value, When the power supply value and the power generation current value are equal to or less than the set values, the power generation braking of the motor (1) is performed by the motor control means and the motor (1) is stopped by the electromagnetic brake (2). A control system for reducing the backlash of an electric vehicle, comprising: performing a stop control of a motor (1) by an electromagnetic brake (2) after applying the brake.