JPH04340301A - Controller for electric automobile - Google Patents

Abstract

PURPOSE:To regenerate kinetic energy at the time of braking and potential energy at the time of traveling on a downhill efficiently, in the form of electric energy, to a battery. CONSTITUTION:A booster type chopper comprising a high frequency reactor L, a switching element Q2 to be turned ON/OFF through a brake mechanism and a rectifier D2 for feeding the electromotive force of the motor to the battery upon turn OFF of the element Q2 is connected between the DC motor and the battery Ba. When the motor is decelerated, a current induced by the electromotive force of the motor flows through the reactor and the element Q2 being turned ON and that current is commutated to the rectifier upon turn OFF of the element Q2 to be recovered efficiently back to the battery through the reactor L. In case of downhill traveling, the electromotive force is higher than the battery voltage and thereby a current flows from the motor through the reactor and the rectifier into the battery to be recovered therein.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device mainly for braking in an electric vehicle.

0002

2. Description of the Related Art FIG. 3 schematically shows the electrical control system of a conventional electric vehicle, and the circuit for a switch that changes the direction of rotation of a DC motor M as a driving power source is omitted. The transistor Q1 is turned on and off at regular intervals by a driving accelerating means such as an accelerator, and as it is operated in the direction of acceleration, the ratio of on to off increases, and the energization rate from the storage battery Ba of the drive power source to the DC motor M increases. becomes larger, and the rotational speed of the DC motor M becomes higher. Note that there is a minimum on-time and a minimum off-time that can be operated depending on the rating of the transistor Q1, and if the cycle is determined from this, the minimum and maximum values of the energization rate are determined, so the current limiting circuit (not shown) The on/off ratio is automatically controlled so as not to exceed the capability of the transistor Q1. Moreover, braking is performed by a mechanical brake. D1 in the figure is a freewheeling diode that serves as a load current path when the transistor Q1 is off.

0003

[Problem to be solved by the invention] Such an electric vehicle is
It was developed following the steam car, and has the great advantage of solving problems such as air pollution and oil resource problems that gasoline and diesel cars have, but it is overwhelming compared to gasoline cars because it requires a heavy and large storage battery. has been done. This is because internal combustion engines, which are commonly used today as driving power sources, can carry a much larger amount of energy than storage batteries.

However, if we consider the original function of a car, a car is a device that moves objects, so if we apply the law of conservation of energy of basic physics to this car, we can say that ``an object with a certain mass has resistance. The total amount of energy when moving in a state where there is no energy and returning to the original origin is zero.'' This means that the driving power source can be made extremely compact. If this law of conservation of energy were to be applied to automobiles, then only electrical and electrochemical energy would be considered, rather than petroleum energy that is simply combusted. Conventional electric vehicles require heavy and large storage batteries because they do not recover any of the energy used as a power source during driving.

SUMMARY OF THE INVENTION Therefore, the technical object of the present invention is to provide an electric vehicle control device that makes it possible to manufacture a vehicle that consumes far less energy than an internal combustion engine driven vehicle.

[0006]

[Means for Solving the Problems] In the present invention, as a technical means for achieving the above-mentioned problems, an electric vehicle control device is constructed as follows. That is, in an electric vehicle control device that runs by supplying DC power from a storage battery as a drive power source to a DC motor as a driving power source via a step-down chopper, a step-up type electric vehicle is provided between the storage battery and the DC motor. In addition to connecting the chopper, this boost type chopper is
a high-frequency reactor connected to the DC motor; a switching element that is turned on and off at regular intervals by a braking mechanism and that flows a current due to the electromotive force of the DC motor that is in a regenerative state when the switching element is turned off; and a rectifier for supplying the voltage to the storage battery, and high frequency blocking capacitors are connected in parallel to the input side and output side of the step-up chopper, respectively.

[0007]

[Operation] When the brake pedal of the braking mechanism is depressed,
The switching element repeats on and off at regular intervals. At this time, since the step-down chopper is in a non-driving state, the DC motor is in a regenerative state and functions as a generator. Therefore, when the switching element is on, even if the electromotive force of the motor is lower than the battery voltage of the storage battery, due to the presence of the high-frequency reactor, current due to the electromotive force of the motor flows through the high-frequency reactor and the switching element, and the switching element When the high-frequency reactor is off, the current flowing through the high-frequency reactor is commutated to the rectifier and collected in the storage battery. The inevitable result is that the electric motor is braked. Here, a high-frequency reactor operates the boost chopper at high frequencies, and a capacitor prevents high-frequency current from flowing to the storage battery and electric motor, respectively, so that the kinetic energy generated when the vehicle decelerates is It can be very efficiently recovered into storage batteries as electrical energy. Moreover, by operating at a high frequency, a small reactor can be used.

On the other hand, when a car runs downhill,
Generally, both the step-down and step-up choppers are in a non-driving state, but since the electromotive voltage of the motor is higher than the battery voltage of the storage battery, current flows from the motor to the storage battery via the high-frequency reactor and rectifier. Potential energy can be recovered as original electrical energy in a storage battery.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the drawings. First, to explain the focus of the present invention, based on the above-mentioned law of conservation of energy,
■When an electric vehicle decelerates, its own kinetic energy is effectively recovered into the storage battery as electrical energy,
■It aims to significantly reduce energy consumption by effectively recovering the potential energy of an electric vehicle when it travels downhill into a storage battery as original electrical energy.

To explain this point in detail with reference to FIG. 2, an electric braking circuit is provided in place of the mechanical braking mechanism of the conventional electric vehicle. That is, a braking transistor Q2 is connected in parallel to a DC motor M, and a storage battery B
An energy recovery diode D2 to a is connected in parallel to the transistor Q1. The braking transistor Q2 is repeatedly turned on and off at regular intervals when the brake pedal is depressed, and the on-time ratio increases depending on the degree of depression. And the driving transistor Q
When the brake pedal is depressed while the driving transistor Q1 is repeatedly turned on and off, the driving transistor Q1
By maintaining the OFF state, the DC motor M enters a regenerative state and functions as a generator. On the other hand, the braking transistor Q2 repeats on and off at regular intervals, and when the braking transistor Q2 is on, a current I1 flows from the motor M through the transistor Q2, and when the transistor Q2 is off, the current is transferred to the diode D2. A current I2 flows through the storage battery Ba, and is recovered by the storage battery Ba as electrical energy. Here, since there is an inductance in the armature La of the DC motor M, even when the electromotive voltage of the motor M is lower than the battery voltage of the storage battery Ba, a current I2 flows from the motor M to the storage battery Ba, and the motor M
is braked.

With only the circuit configuration shown in "FIG. 2" which shows the operating principle of the present invention, the original purpose of the braking transistor Q2 is limited to braking the electric motor M, and the recovery efficiency of electric energy is poor. The circuit configuration is as shown in 1. That is, as shown in "Fig. 2", armature La of electric motor M
Instead of using the inductance of
, a braking transistor Q2, and an energy recovery diode D2 constitute a step-up chopper, and high-frequency blocking capacitors C1 and C2 are connected in parallel to the input and output sides of this step-up chopper, respectively. The reason why the high frequency reactor L is used in this way is because the armature La of the DC motor M generally does not have an iron core suitable for high frequency current, and also because of the skin effect of the electric wire when the wiring is long. This is because the apparent resistance loss increases, and this causes the electric energy storage battery B to
The efficiency of recovery to a can be greatly improved. Further, high frequency current is prevented from flowing into the storage battery Ba and the DC motor M by the capacitors C1 and C2, respectively.

Next, the operation of the above embodiment will be explained. During running, DC power from the storage battery Ba is supplied to the DC motor M by a step-down chopper composed of a running transistor Q1 that repeats on and off, a high frequency reactor L, and a diode D1, and the motor M is in a power running state. The wheels are driven to rotate. Then, when the brake pedal is depressed, the DC motor M continues to rotate and enters the regenerative state even though the driving transistor Q1 remains in the off state, and functions as a generator to generate an electromotive force Em.
occurs. On the other hand, since the braking transistor Q2 is repeatedly turned on and off, even if the electromotive force of the motor M due to the high frequency reactor L is lower than the battery voltage of the storage battery Ba, the braking transistor Q2 is turned on via the reactor L and the transistor Q2. current flows. At this time, the battery voltage of storage battery Ba is Vb, the reactance of reactor L is R, and the braking transistor Q
If the on-time of Q2 is t, the current I1 flowing through the braking transistor Q2 in the on state is I1=(Em/R)t
It is expressed by the formula. The final value I1 of this current I1 at each turn-on
e is I1e = (Em /R)Ton...(If Ton is the time during which the braking transistor Q2 is on)
It is expressed by the formula 1).

Next, when the braking transistor Q2 is turned off, the current flowing through the reactor L is commutated to the recovery diode D2, and I2=I1e-{(Vb-Em)/
A current I2 of R}t flows. The final value I2e of this current I2 at each OFF time is I2e =I1e-, where Toff is the time during which the braking transistor Q2 is OFF.
{(Vb-Em)/R}Toff...It is represented by the formula (2). However, since there is a recovery diode D2, the current I2 does not fall into the negative region even if the off time Toff is longer than necessary. If the current I2 does not become zero because this time Toff is short, the final value I2e of the current I2 at that time becomes the initial value of the next current I1, and I1=I2e(Em/R)e, and the current I2
1. Although I2 appears to rise infinitely, in reality, the electromotive force of the motor M decreases, and the aforementioned current limiting circuit is turned on to prevent the current I1 from exceeding the capability of the braking transistor Q2. Since the ratio between the time Ton and the off time Toff is automatically controlled, there is no problem. Also, in order to prevent the high frequency reactor L from becoming huge,
It is clear from equations (1) and (2) that the on time Ton and the off time Toff should be set in short time units. Therefore, as described above, the reactor L is made smaller by operating the boost chopper at a high frequency.

On the other hand, when the electric vehicle runs downhill, both transistors Q1 and Q2 are generally maintained in the OFF state, but at this time, the electromotive voltage Em of the electric motor M becomes higher than the battery voltage Vb of the storage battery Ba. Electric motor M
A current I2 flows from the storage battery Ba through the diode D2. That is, the potential energy possessed by the vehicle itself can be effectively recovered into the storage battery Ba as the original electrical energy.

[0015]

As described above, according to the electric vehicle control device of the present invention, the step-up chopper that operates at a high frequency is driven during braking, and the current generated by the electromotive force of the electric motor is very efficiently recovered in the storage battery, and the inevitable As a result, the electric motor is braked, and the capacitor prevents high-frequency current from flowing to the electric motor and storage battery. When the car runs downhill, the electromotive force of the electric motor is supplied to the storage battery via the reactor and rectifier and recovered. With this configuration, it is possible to provide an electric vehicle that consumes far less energy than existing vehicles driven by internal combustion engines.

[Brief explanation of the drawing]

FIG. 1 is a schematic electrical circuit diagram of an electrical control system according to an embodiment of the present invention.

FIG. 2 is an electric circuit diagram for explaining the focus of the present invention.

FIG. 3 is a schematic electrical circuit diagram of an electrical control system of a conventional electric vehicle.

[Explanation of symbols]

M DC motor Ba Storage battery Q2 Braking transistor (switching element) L
High frequency reactor D2 diode (rectifier)

Claims (1)

[Claims] 1. An electric vehicle control device configured to run by supplying DC power from a storage battery as a driving power source to a DC motor as a driving power source via a step-down chopper, wherein: between the storage battery and the DC motor; A step-up chopper is connected to the DC motor, and the step-up chopper is connected to a high-frequency reactor connected to the DC motor, and a braking mechanism turns on and off at a constant cycle, and when the DC motor is turned on, a current generated by the electromotive force of the DC motor is generated. The step-up chopper is composed of a switching element that allows current to flow, and a rectifier that supplies the electromotive force to the storage battery when the switching element is turned off, and high-frequency blocking capacitors are connected in parallel to the input side and output side of this step-up chopper, respectively. Characteristic electric vehicle control device.