JPH07298410A - Power source structure for electric cart - Google Patents

Abstract

PURPOSE:To provide a power source structure for an electric cart, which can avoid a battery getting in the overcharge condition by the quantity of electricity regenerated with the regenerative braking even if the regenerative braking condition extends for a long period. CONSTITUTION:This power source structure for an electric cart is equipped with a drive control means 11s, which drives an electric motor 3 for running with a battery B, and a brake control means 12, which brakes the generation of the electric motor 3, and a main battery B is composed of a main battery 8 and a spare battery 9, and this power source structure is further provided with a battery changeover means B which selects the main battery 8 or the standby battery 9 and connects it to the electric motor 3. And, the battery changeover means A is so constituted as to connect the spare battery 9 with the electric motor 3, based on the command to change the electric motor 3 over into the regenerative braking condition, and to connect the spare battery 9 or the main battery 8 to the electric motor 3, in condition that the dischargeable standby battery 9 is prior to the main battery 8, based on the command to change the electric motor 3 over into drive condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power source structure for an electric cart equipped with drive control means for driving an electric motor for traveling with a battery and braking control means for dynamically braking the electric motor.

[0002]

2. Description of the Related Art Conventionally, in this type of electric cart,
For example, Japanese Patent Application No. 5-118889 filed by the applicant earlier
In addition to the electromagnetic brake, the electric braking for traveling is not performed when the electric motor for traveling is not driven, and the dynamic braking is performed by short-circuiting the terminals of the electric motor, or 2. Description of the Related Art It is well known that an electromotive force from an electric motor acting as a generator is regenerated to a battery for braking during dynamic braking.

[0003]

By the way, in the case of braking by regenerating the electromotive force from the electric motor acting as a generator to the battery at the time of dynamic braking, the braking is comparatively long in a mountainous area. When traveling on a slope, the vehicle is always in the dynamic braking state during the traveling, and a considerable amount of current is regenerated to the battery. Then, when the vehicle runs on such a long downhill with the battery close to the fully charged state, the battery becomes overcharged, resulting in a short battery life. The present invention has been made in view of the above circumstances, and even when the dynamic braking state is long, the power of the electric cart that can avoid the battery from being overcharged by the amount of electricity regenerated by the dynamic braking. The purpose is to provide the source structure.

[0004]

In order to achieve the above object, a power source structure for an electric cart according to the present invention includes drive control means for driving an electric motor for traveling with a battery,
A battery switching unit that includes a braking control unit that dynamically brakes the electric motor, and that configures the battery with a main battery and an auxiliary battery, and selects the main battery and the auxiliary battery to connect to the electric motor. And the battery switching means connects the auxiliary battery and the electric motor based on a command to switch the electric motor to a dynamic braking state, and discharges the battery based on a command to switch the electric motor to a driving state. It is characterized in that the spare battery or the main battery is configured to be connected to the electric motor in a state where the possible spare battery is prioritized over the main battery. The operation and effect of this characteristic configuration are as follows.

[0005]

In other words, the battery is divided into the main battery and the spare battery, and the battery that regenerates the electromotive force generated by the electric motor braking is determined as the spare battery. Prevents the main battery from being unduly overcharged because it does not recharge it. Also, in the battery, it will be used preferentially from the spare battery that can be discharged,
By using a spare battery that can be discharged by charging the regenerative current during braking, overcharging of the spare battery can be avoided as much as possible.

[0006]

Therefore, even if the electromotive force generated by the electric braking from the electric motor is regenerated and charged into the battery, the main battery that is mainly used is not regeneratively charged and only the spare battery is charged. By regeneratively charging and using the spare battery with priority, the problem that the main battery and the spare battery become overcharged can be avoided, the main battery life can be extended, and the dynamic braking is comparatively performed. It is now possible to obtain an electric cart that can withstand long downhill driving.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a scooter type small electric vehicle as an example of an electric cart. This small electric vehicle includes a vehicle body frame 5 supported by a front wheel 2 steered by a steering wheel 1 and a pair of left and right rear wheels 4, 4 driven by an electric motor 3, a battery B, a steering seat. 6 and the control device 7 are installed and configured.

As shown in FIGS. 1 to 3, the battery B is composed of two main batteries 8 and four spare batteries 9 arranged at the front end of the vehicle body frame 5. Further, a charger 10 that can charge only the main battery 8 is provided. Further, a drive control means 11 for driving the electric motor 3 with a PWM signal corresponding to the accelerator amount is provided, and a braking control means for switching the circuit of the electric motor 3 so as to perform dynamic braking when the PWM signal is at a low level. It has twelve. The braking control means 12 is also configured as means for sequentially charging the electromotive force from the electric motor 3 during the dynamic braking from a predetermined spare battery 9. The order in which the spare batteries 9 are charged is set in advance by hardware or by software so as to be automatically set under the control of the braking control means 12. That is, when the first spare battery 9 is fully charged by charging the regenerative current from the electric motor 3 during dynamic braking, the charging of the first spare battery 9 is stopped and the second spare battery 9 is stopped. It is configured to automatically charge. Further, when the electric motor 3 is driven, the drive control means 1 is selected by selecting the main battery 8 and the spare battery 9.
A battery selection connection unit 13 that forms a switching circuit connected to 1 is provided between the drive control unit 11 and the main battery 8 and the spare battery 9. The battery selection connection means 13 is controlled by the battery connection control means 14. The battery connection control means 14 determines whether the load of the electric motor 3 is in a light load state and the spare battery 9 is in a dischargeable state based on the detection result of the load of the electric motor 3 and the terminal voltage of each spare battery 9. In some cases, the spare battery 9 which can be discharged is connected to the drive control means 11, the main battery 8 is switched so as not to be connected to the drive control means 11, and the load of the electric motor 3 is in a light load state and the spare battery 9 is discharged. If it is impossible, the main battery 8 is connected to the drive control means 11, the spare battery 9 is switched so as not to be connected to the drive control means 11, the load of the electric motor 3 is in a heavy load state, and the spare battery 9 is discharged. If it is possible, connect the main battery 8 and the dischargeable spare battery 9 together to the drive control means 11, It is configured to allow a large current supplied to the moving motor 3. In addition, in the state where the spare battery 9 cannot be discharged,
When the electric motor 3 is in a heavy load state, only the main battery 8 is connected to the drive control means 11. Therefore, when the auxiliary battery 9 is in a dischargeable state, the auxiliary battery 9 is discharged more preferentially than the main battery 8. Here, the braking control means 12, the battery selection connection means 13, and the battery connection control means 14 constitute a battery switching means A.

This electric cart has a plurality of spare batteries 9 installed in advance according to the user's usage.
A part of ... is used as a main battery that does not perform regenerative charging together with the main battery 8, and all spare batteries 9
Can be used as the original spare battery dedicated to charging during dynamic braking. That is, for example, assuming that the main battery 8 has a total capacity of 50 Ah, the spare battery 9 has a total capacity of 10 Ah, and four spare batteries 9 are provided as in the above-described embodiment, a place with a lot of sloped land such as a mountainous area. When using, as shown in Figure 4,
When the circuit is set so that all of the spare batteries 9 are exclusively used for charging at the time of dynamic braking, and when the spare batteries 9 are used on a flat land with a small amount of sloping ground, as shown in FIG. Together with the main battery,
The circuit may be set so that only the remaining two spare batteries 9 are dedicated to charging during dynamic braking.

Next, the suspension structure of the electric cart will be briefly described. That is, as shown in FIGS. 2 and 6, a support frame 5a that supports the rear wheels 4 and 4 is pivotally attached to the vehicle body frame 5 about a horizontal axis P and is also supported by the support frame 5a. A coil spring 15 is laid across 5a and the rear end of the vehicle body frame 5 to form a suspension structure. The support frame 5a for the coil spring 15 and the vehicle body frame 5
The coil spring 15 is attached to the coil spring 15 by fastening the bolt, and the bending prevention cylinder member 16 of the coil spring 15 is simply surrounded by the coil spring 15. Therefore, in order to restrict the bending of the coil spring 15, a bar-shaped member is provided in the coil spring for suspension, and a bar-shaped member is provided on the bar-shaped member as the upper and lower hits of the coil spring. It's easy.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a block diagram showing a battery, a means for driving and braking an electric motor, and the like.

FIG. 2 is an overall side view showing an electric cart

FIG. 3 is an overall plan view showing an electric cart

FIG. 4 is an explanatory diagram showing how to use a main battery and a spare battery in this embodiment.

FIG. 5 is an explanatory diagram showing how to use a main battery and a spare battery when mainly used in flatland traveling.

FIG. 6 is a side view showing a suspension structure.

[Explanation of symbols]

 3 Electric Motor 8 Main Battery 9 Spare Battery 11 Drive Control Means 12 Braking Control Means A Battery Switching Means B Battery

Claims (1)

[Claims] 1. A drive control means (11) for driving an electric motor (3) for traveling with a battery (B), and a braking control means (12) for dynamically braking the electric motor (3), The battery (B) includes a main battery (8) and a spare battery (9), and the main battery (8) and the spare battery (9)
And a battery switching means (A) for connecting to the electric motor (3) is provided, and the battery switching means (A) is operable to switch the electric motor (3) to a dynamic braking state based on a command. Spare battery (9)
And the electric motor (3) are connected to each other, and the dischargeable auxiliary battery (9) is prioritized over the main battery (8) based on a command to switch the electric motor (3) to a driving state, The spare battery (9)
Alternatively, a power source structure for an electric cart configured to connect the main battery (8) to the electric motor (3).