JP3123686B2 - Hybrid car power generation controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generation control device for a hybrid car that runs by driving an electric motor with the battery while charging the battery with an engine generator.

[0002]

2. Description of the Related Art The prior art is not clear because a hybrid car has not been put into practical use, but FIG. 5 shows a scheme using a synchronous generator.

[0003] A rectifier 3 converts an AC output of a synchronous generator 2 coupled to an engine 1 into a direct current, and charges a battery 4. The capacitor 5 is connected in parallel with the battery 4, converted into another AC by the inverter 6, and the electric motor 7 is driven.
The current detector 8 detects the output current of the rectifier 3.

The battery voltage reference 9 and the voltage of the battery 4 are detected and compared by a voltage detector 10, amplified by an amplifier 11 and used as a DC current reference of the generator, compared with the output of the current detector 8, and compared by an amplifier 12. IGBT 14 is amplified by PWM circuit 13
WM control is performed to cause a field current if to flow through the field winding 2a. The diode 15 is for freewheeling. With the circuit configured as described above, charging control can be performed so that the battery voltage becomes constant while limiting the output current of the synchronous generator.

[0005]

There are two problems in the system configured as described above.

First, the battery voltage changes by about 40% depending on the state of charge of the battery. Furthermore, since the engine speed also changes by about 40%, satisfactory charging cannot be performed unless the terminal voltage of the generator 2 is changed at least twice. As a result, the apparent generator capacity is approximately doubled, the weight is increased, and the fuel efficiency of the hybrid car is reduced.

Second, when a cylindrical generator is used as the synchronous generator, the control of the field current becomes unstable as shown in FIG. That is, the field current if the inductance of the field by applying a field voltage V _f at time T ₁ rises linearly, the generator voltage is substantially linearly increased. Then, the DC current id increases and exceeds the battery voltage at time T _2. Then, the field current if also increases due to the coupling action between the generator winding and the field winding, and this action becomes a positive feedback action, and id rapidly increases. The time T _2, hereinafter, as shown in FIG. 6 from the fact that no field voltage is applied and this is obvious. Core is saturated Beyond a certain point, to attenuate the positive feedback action, id is zero at time T _3.

Although this phenomenon occurs when the load is a battery or a capacitor, the gain from the generator voltage to the generator current increases, but this phenomenon does not surface with a general LR load. It is an object of the present invention to reduce the size and weight of the generator as much as possible to increase the efficiency and to eliminate the unstable state due to the positive feedback action as described above.

[0009]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a motor driven by a power supply comprising a rectifier that converts the output of a generator driven by an engine into a direct current and connects a battery to the direct current. In the hybrid car that drives the rectifier, a boost chopper circuit is provided on the output side of the rectifier to control the generator output current or the DC side voltage.
Further, by controlling the field of the generator, the output voltage of the generator is controlled so that the rectified voltage is equal to or slightly lower than the DC voltage. Further, the generator is a permanent magnet type synchronous generator.

[0010]

Since the DC voltage is controlled by the step-up chopper circuit, the degree of freedom of the generator voltage can be increased and the size can be reduced. Further, since the generator voltage is controlled to be lower than that of the battery, even if a positive feedback action occurs due to the generator current, the current can be controlled by the boost chopper without exceeding the battery voltage. The step-up chopper can perform high-speed control and can respond for about 1 ms, so that stable current control is performed.

[0011]

FIG. 1 shows an embodiment of the present invention. The same parts as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted.

The reactor 16 is connected to one end of the rectifier 3 on the output side.
IGBT 17 is connected between the connection point of reactor 16 and diode 18 and the negative side of capacitor 5 to form a step-up chopper circuit. The voltage reference 9 is a function generator 19
, The generator reference voltage V _19, which is lower than the voltage reference 9, is input to the amplifier 20.

The output voltage of the rectifier 3 is detected by a voltage detection circuit 21 and compared with a generator reference voltage, amplified by an amplifier 20 and subjected to PWM.
The generator 22 is controlled by the PWM control of the IGBT 14 by the circuit 22 to adjust the field current.

On the other hand, the voltage reference 9 of the battery voltage is compared with the battery voltage and is amplified by the amplifier 11 to be used as the generator output current reference.
The IGBT 17 is driven via the WM circuit 13.

[0015] a current reference V ₁₁ amplifies an error by an amplifier 11 so that the value detected by the voltage detector 10 to the battery reference voltage and battery voltage set by the voltage reference 9 matches, the value detected by the current detector 8 The signals are amplified by the amplifier 12 so that they match, and the PWM control of the IGBT 17 is performed by the PWM circuit 13. Thus, the battery 4 is charged by the boost chopper that controls the output current of the rectifier 3.

On the other hand, the voltage reference 9 outputs a voltage reference V ₁₉ which is always lower than the battery voltage reference, via the function generator 19, detects the DC voltage of the rectifier 3 with the voltage detector 21, compares the DC voltage, and compares the DC voltage with the amplifier 20. To perform PWM control on the IGBT 14. Thus, the rectified voltage of the generator 2 is controlled to be slightly lower than the battery voltage.

This situation will be described with reference to FIG. When the battery voltage _VDC is changed as shown in FIG.
When the generator AC output voltage and V _AC, the rectified output voltage is 1.
It becomes 35V _AC . This rectified voltage is always controlled by the field of the generator so as to be slightly lower than V _DC , and the voltage of (V _DC -1.35 V _AC ) is boosted by the boost chopper. The lower the step-up voltage, the higher the efficiency and the more power can be taken from the generator.

When the number of revolutions of the engine is N ₁ or N ₂ , the control for limiting the maximum output voltage 1.35 V _AC to N ₁ or N _{2 in} FIG. Can be used with a high magnetic flux density, so that the generator can be reduced in size and weight. As one method of performing such voltage limit control, the generator maximum voltage is proportional to the rotation speed by limiting the field current of the generator.
Another method is to detect the number of revolutions of the engine 1 and use the function generator 19
There is a way to change the output of

By performing such control, the generator can be reduced in size and weight, and since the generator output current is controlled at a high speed by the step-up chopper, the unstable phenomenon accompanying the positive feedback of the conventional method is eliminated.

First, the current is controlled at high speed by the boost chopper, the generator voltage is controlled to be lower than the battery voltage, and the control is performed to limit the maximum value of the generator voltage by the engine speed. An unstable phenomenon due to the positive feedback of the current is eliminated and stable control is achieved. Secondly, by controlling the rectified voltage slightly lower than the battery voltage, the boost chopper can always be operated with high efficiency. Third, the maximum value of the generator voltage is limited by the engine speed, and the boost chopper section performs boost charging to significantly reduce the size of the generator. This ratio is the sum of the variation width of the battery voltage _{VDC and} the variation width of the engine speed, and generally results in a small generator that is 以下 or less of the conventional method. For this reason, there is an advantage that the generator becomes highly efficient due to a reduction in weight and a decrease in windage.

In FIG. 2A, (V _DC -1.35 V _AC )
= K (constant value), but V _DC / 1.
Control of fixed ratio, such as 35V _AC = K, V _DC and various combinations can be considered a control such that there are areas of V _DC <1.35V _AC is a minimum value. (If the _VDC is low, the battery is over-discharged, so it is conceivable to operate by increasing the current from the generator.) Fig. 3 shows an example of using a permanent magnet generator as the generator. Show.

The permanent magnet generator 2a is used, the reactor 16 in FIG. 1 is omitted in FIG. 3, and the leakage inductance of the winding 2b is used. Without further detects a generator voltage, detects the on-off ratio V ₃₀ of the step-up chopper with the duty detector 30 from the ON-OFF signal of the step-up chopper, compares the voltage e and V ₃₀ of the duty set value 31 amplifier 32 The engine speed is controlled by an engine speed control circuit that controls the gasoline injection amount of the engine. This situation is shown in FIGS.

When the engine speed is constant, the output rectified value of the permanent magnet generator is proportional to the engine speeds N ₁ , N ₂ and N _{3 as shown} in FIG. If the generator voltage is selected to be N ₃ when the engine speed is constant, the efficiency including the boost chopper becomes the highest.

When the engine speed N can be varied, as shown in FIG. 2C, 1.35 V _{AC is controlled} to f (N), that is, N is varied so as to be proportional to V _DC . In FIG. 3, PWM
This control is achieved by controlling the rotation speed N so as to control the duty ratio at a constant. In addition, as shown in FIG.
Controlling _VAC works similarly. It is also conceivable to control the rotational speed stepwise as indicated by N ₄ , N ₅ and the like. It is needless to say that the duty ratio control of FIG. 3 can be used in FIG. Further, if the boost chopper circuit employs a system using the high-speed diode 3a shown in FIG. 4A, the number of diodes passing therethrough is reduced by one, and the efficiency is increased accordingly.

Further, as shown in FIG.
If the IGBTs (17a, 17b, 17c) are used, the number of diodes passing therethrough can be further reduced and the efficiency can be increased. Of course, it is needless to say that six IGBTs can be used. The current is detected by current transformers 40 and 41, rectifier 42, resistor 43
May be detected. The chopper element has been described as an IGBT, but the operation is exactly the same for other elements.

[0026]

As described above, according to the present invention, since the voltage control of the battery is performed by the step-up chopper, the degree of freedom in setting the generator voltage is increased. In the generator with the field winding, the unstable phenomenon disappears, and the maximum value of the generator voltage can be made proportional to the rotation speed, so that the generator can be reduced in size and weight. In the permanent magnet generator, if the generation voltage is optimally selected or the engine speed is controlled, it is possible to provide a smaller, lighter, and more efficient hybrid car power generation control device.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIGS. 2A and 2B are diagrams for explaining the operation of the present invention, wherein FIG. 2A is a characteristic diagram for the embodiment of FIG. 1, and FIGS.

FIG. 3 is a configuration diagram of another embodiment of the present invention.

FIG. 4 is another configuration diagram of a step-up chopper.

FIG. 5 is a configuration diagram of a conventional device.

FIG. 6 is a waveform chart for explaining a problem of the conventional device.

[Explanation of symbols]

1: engine, 2: synchronous generator, 3: rectifier,
4 ... Battery, 5 ... Capacitor, 6 ... Inverter, 7 ... Motor, 8 ... Current detector, 9 ... Voltage reference, 10 ... Voltage detector, 11, 12 ... Amplifier, 13 ... P
WM circuit, 14 ... PWM circuit, 14 ... IGBT, 15
... diode, 16 ... reactor, 17 ... IGBT, 18
... diode, 19 ... function generator, 20 ... amplifier, 21 ...
Voltage detector, 22: PWM circuit, 2A: Permanent magnet generator, 30 duty detector, 31: Duty set value,
32 ... amplifier, 33 ... engine speed control circuit, 3
a: high-speed diode, 40, 41: current transformer, 42: rectifier,
43… resistance.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Chihiro Okado 2-24-24 Harumi-cho, Fuchu-shi, Tokyo Toshiba FA System Engineering Co., Ltd. (56) References JP-A-5-111186 (JP, A)

Claims (3)

(57) [Claims] 1. A hybrid car in which an output of a generator driven by an engine is converted into a direct current by a rectifier and a motor is driven by a power supply having a battery connected to the direct current side, wherein a boost chopper circuit is provided on an output side of the rectifier. Wherein the generator output current or the DC side voltage is controlled. 2. The apparatus according to claim 1, wherein a voltage obtained by rectifying an output voltage of the generator by controlling a field of the generator is equal to or slightly lower than the DC side voltage. A power generation control device for a hybrid car. 3. The power generation control device for a hybrid car according to claim 1, wherein said generator is a permanent magnet type synchronous generator.