JPH0516280B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power generation device that includes a generator whose power source is an engine that drives a vehicle such as an automobile, and supplies DC power to an electrical load of the vehicle.

BACKGROUND ART Conventionally, it has been known that engine speed hunting tends to occur when the engine is idling, and this problem is particularly noticeable when a specific electrical load is applied to the generator.

The following reasons can be considered for this hunting. That is, when the engine speed decreases for some reason, the voltage regulator that turns on and off the field current operates to increase the on-time ratio in order to increase the field current in response to the reduction in the generated voltage. However, this increases the engine braking torque. This further acts in the direction of lowering the engine speed. However, a decrease in engine speed simultaneously results in a decrease in engine friction loss and an increase in engine output. This increase in engine output can be easily understood by considering, for example, the basic equation of an electronically controlled fuel injection system in which the valve opening time is generally controlled, that is, engine rotation speed x fuel injection time - constant. This reduction in friction losses and increase in engine power conversely causes an increase in generator output, causing the voltage regulator to operate to increase the off-time ratio to reduce field current. This acts to further reduce the engine braking torque and further increase the engine speed. However, this increase in engine speed in turn causes an increase in engine friction losses and a decrease in engine output. When the cycle of increase/decrease in the engine speed mentioned above has a predetermined relationship with the on/off cycle of the field current, the amplitude of fluctuations in the engine speed becomes large and hunting occurs.

A technique for changing the field current stepwise when a specific electrical load is applied in order to change the amount of power generation according to the electrical load is disclosed in, for example, Japanese Patent Application Laid-Open No. 1983-1999.
108536, Utility Model Application No. 51-163406, and Utility Model Application No. 55-82035. However, all of these technologies are circuits that use on-off type voltage regulators, so even if the magnitude of the field current changes, the problem of the above-mentioned on-off cycle remains, and furthermore, the electrical load of the on-board generator remains. It is common for there to be multiple, not just one,
According to this method, the degree of hunting changes depending on whether a plurality of electrical loads are applied alone or in combination, but there is a problem in that the above-mentioned known techniques cannot deal with this problem.

On the other hand, a battery has a characteristic that the more its deterioration progresses, the faster the terminal voltage drops during discharge when the field current is cut off, and the generator itself does not necessarily produce the same output voltage with the same field current value due to manufacturing errors or deterioration. Since this does not necessarily occur, there are variations in the rise in battery terminal voltage during charging. According to this, even if the field current of the same value commensurate with the absolute amount of electric load is supplied to the field coil, the battery voltage will rise or fall depending on the vehicle. Therefore, there is a problem in that the battery voltage may exceed a predetermined upper limit value or fall below a predetermined lower limit value. On the other hand, if the field current is immediately connected or disconnected in response to exceeding a predetermined upper limit value, exceeding a predetermined lower limit value, or falling below a predetermined lower limit value, it is similar to using a conventional on-off type voltage regulator. There is also a problem that causes engine speed hunting. Therefore, the present invention is an on-vehicle power generation device that does not have the above-mentioned problems, secures the amount of power generated according to the power consumption, and makes it possible to improve the stability of engine operation. It is an object of the present invention to provide an on-vehicle power generation device that can prevent changes in output voltage due to such factors.

The on-vehicle power generation device according to the present invention includes a generator 1 using a vehicle drive engine as a power source, a conversion means for converting the output power of the generator into DC power, and a plurality of electrical loads mounted on the vehicle. An on-vehicle power generation device comprising relay means (SW1 to SW) 4 that selectively supplies DC power, and generates a selection content detection signal of a magnitude corresponding to the selection content of the electrical load by the relay means. a detection means 8; and field current supply means 7, 9 which select one of the field current values of a predetermined magnitude in response to the selective content detection signal and supply it to the field coil of the generator. .
1, 25, 27, 28, and a second adjusting means 22 for reducing the selected field current value by a second predetermined amount when the voltage of the DC power exceeds a predetermined upper limit value;
30, 32, and 33.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a device for controlling a field current flowing through a field coil 2 of an alternator 1 driven by an on-vehicle engine (not shown).

The output of the alternating current generator 1 is rectified by a rectifier circuit 3 to be converted into direct current, and is supplied to both positive and negative terminals of a battery 4 . Note that in this case, the negative terminal of the battery 4 is grounded. Both positive and negative terminals of the battery 4 are connected via an ignition switch 5 to a plurality of electrical loads 6 such as a heater fan, a headlamp, and a radiator fan.

On the other hand, a control circuit 7 configured by a microprocessor etc.
The duty ratio corresponds to the load signal voltage El from the load detection circuit 8 which detects the absolute amount of the overall magnitude and generates the load signal voltage El corresponding to this, the engine rotation speed signal Ne, and the throttle opening signal θth.
The D _F pulse signal is supplied to the clip control circuit 9. The duty ratio D _F is the ratio of the on time of the pulse signal to the set time (for example, TDC interval or timer set time). Clip control circuit 9
As long as the battery voltage is below the set maximum value,
A pulse voltage is supplied to the base of the power transistor Q in accordance with the supplied pulse signal. Since the collector of the power transistor Q is connected to the battery positive terminal via the field coil 2, and the emitter is grounded, a field current corresponding to the pulse voltage of the base can be obtained. Note that the clip control circuit 9
Even if the duty ratio from the control circuit 7 is controlled according to the absolute value of the electrical load, the output voltage of the generator may rise beyond the maximum voltage setting of the electrical circuit, resulting in Specifically, when a situation occurs in which the battery voltage exceeds a set maximum value, no pulse voltage is supplied and zero voltage is generated.

Next, the operation of the control circuit 7 shown in FIG. 1 will be explained with reference to the flowchart shown in FIG.

In the control circuit 7, it is started at a certain period or at intervals of engine rotation, and first, the engine rotation speed is controlled.
Ne and the first predetermined rotation speed lower than the idle rotation speed
N _CR (corresponding to the so-called cranking rotation speed) is compared (step 10). When the engine rotational speed Ne is smaller than the first predetermined rotational speed _NCR , which is lower than the engine rotational speed at which the generator starts outputting, the duty ratio D _F of the output pulses of the control circuit 7 is set to 0% (step 11). On the other hand, when the engine rotation speed Ne is larger than the first predetermined rotation speed N _CR , the engine rotation speed Ne and the second predetermined rotation speed at which hunting, which is larger than the idling rotation speed, become almost no problem.
Compare with _NSR (Step 12). When the engine speed Ne is greater than the second predetermined speed _NSR , the control circuit 7 sets the duty ratio D _F to 100% (step 13). That is, in this case, the content of the field current command is maximum. On the other hand, when the engine speed Ne is below the second predetermined speed _NSR , the throttle opening θth is compared with the idle throttle opening _θIDL (step 14). At this time, the throttle opening θth
When is larger than the idle throttle opening θ _IDL , the duty ratio D _F is 100% and the content of the field current command is maximum. On the other hand, if the slot opening θth is less than the idle throttle opening θ _IDL , the load signal voltage El is read (step 15). Control circuit 7
The duty ratio can be calculated from the data map provided in the
_DF is determined (step 16), and a pulse signal having a duty ratio equal to the obtained duty ratio _DF is supplied to the clip circuit 9. Clip circuit 9
The pulse signal passed through drives the power transistor Q, and a field current having an average value proportional to the magnitude of the duty ratio D _F flows through the field coil 2. Since the output voltage of the generator 1 is proportional to the magnitude of the field current, the output voltage of the generator 1 is proportional to the electric load 6.
It will change depending on the absolute magnitude of .

FIG. 3 is a graph showing an example of the relationship between the value of the duty ratio D _F and the value of the load signal voltage El on the data map.

FIG. 4 shows a specific circuit example of the load detection circuit 8, in which a headlight HL, a rear heating wire RH, a radiator fan motor M ₁ , and a heater fan motor M ₂ are illustrated as electric loads. Each electric load is turned on and off by switches SW1 to SW4. The load detection circuit 8 has a diode
The on/off states of the switches _SW1 to _SW4 are monitored via _D1 to _D4 . That is, the diode D ₁ ~
The voltage that has passed through _D4 is appropriately amplified by buffer amplifiers _A1 to _A4 including transistors _Q1 to _Q6 , and is output as voltages _V1 to _V4 weighted for each electrical load, and is output from the voltage divider DV. After being added together with the output voltage Vo of , it is supplied to the amplifier _A5 , and is further amplified appropriately and output as the load signal voltage El.

As described above, the field current value is determined by the command duty ratio from the control circuit 7.
Due to factors such as aging of the battery or a decline in the power generating capacity of the generator, the output voltage of the power generator, that is, the voltage across the battery 4, may fall below the predetermined lower limit. Sometimes even more.

Therefore, in the present invention, the operation shown in the flowchart of FIG. 5 is added to the control circuit 7. That is, after selecting the duty ratio D _F on the data map according to the load signal voltage El, the battery voltage V _B is detected (step 20), and this battery voltage V _B is compared with a predetermined lower limit value V _BL (step 21). ). When the battery voltage _VB is greater than or equal to the predetermined lower limit value _VBL , it is compared with the predetermined upper limit value _VBH (step 22). The predetermined upper limit value V _BH is set lower than the maximum voltage value set by the clip control circuit 9. As long as the battery voltage _VB is below the predetermined upper limit value _VBH, both the upper limit timer and lower limit timer in the control circuit 7 are reset and remain stopped (step 2).
3), the duty ratio D _F is D _F =D _F +a%×
It is corrected by the formula _nSR (a is 10, for example) (step 24). Here, n _SR is a coefficient with an initial value of zero. Therefore, as long as the battery voltage V _B remains between the predetermined lower limit value V _BL and the predetermined upper limit value V _BH after startup, the coefficient n _SR is zero and the duty ratio
D _F remains the data map value determined by the load signal voltage El.

However, due to battery 4 deterioration or generator 1
The value of the battery voltage V _B obtained by the duty ratio D _F determined by the equation in step 24 may fall below the predetermined lower limit value V _BL due to reasons such as a decrease in the performance of the battery. In such a case, it is determined whether the lower limit timer in the control circuit 7 has timed up (step 25), and if it has not timed up, only the upper limit timer is reset and remains stopped, and the lower limit timer starts counting up. At the same time, when the lower limit timer has not timed up during the subsequent startup, the count-up operation is continued (step 26). Thus, V _B <V _BL
If the condition continues for a predetermined time or longer and the lower limit timer times out, the battery voltage at that time V _B
The rate of change of △V _B (for example, the difference between the previous sampling value and the current sampling value) and n _SR addition guard value +
V _BG1 (V _BG1 > 0) (step 27), and when the rate of change △V _B is smaller than n _SR addition guard value + V _G1 , the minimum digit (for example, 1) is added to the coefficient n _SR (step 28 ). Furthermore, when the rate of change ΔV _B is larger than _nSR addition guard value + V _BG1 , the value of the coefficient n _SR is left unchanged. Next, the lower limit timer is reset and restarted, while the upper limit timer is reset and remains stopped (step 2).
9).

That is, when the battery voltage V _B is continuously lower than the lower limit value V _BL for a predetermined time determined by the lower limit timer, the duty ratio D _F is forcibly increased by a%, the field current increases, and the battery voltage decreases. Voltage
This causes _VB to rise. However, the rate of change of battery voltage V _B △V _B is a predetermined guard value, that is, n _SR
When the addition guard value is used, the duty ratio D _F has reached the required value, and there is a high possibility that the battery voltage will quickly exceed the lower limit value V _BL , and there is also a risk that V _B will exceed the upper limit value V _BH . Therefore, since there is a possibility that a change in the duty ratio D _F may cause unnecessary hunting, step 28 is skipped and the field current is maintained at the current value without increasing the coefficient n _SR and the battery voltage V _B is changed. This is to prevent excessive rise.

Although an excessive rise in battery voltage V _B can be prevented in this way, battery voltage V _B may also exceed a predetermined upper limit value V _BH and have an adverse effect on battery 4 or electrical load 7 . Therefore, when the battery voltage V _B exceeds the predetermined upper limit value V _BH , it is determined whether the upper limit timer has timed up (step 30), and if it is the first determination after startup, the upper limit timer is started to count up; If the timer has not timed up, the upper limit timer is allowed to continue counting up, while the lower limit timer is reset and remains stopped (step 3).
1), the duty ratio D _F is determined with _the coefficient _nSR unchanged (step 24). If this condition continues, the upper limit timer will time out, and the rate of change of battery voltage V _B at that time will decrease △
Compare V _B and n _SR subtraction guard value - V _BG2 (V _BG2 > 0) (Step 32) and if the rate of change △V _B is smaller than n _SR subtraction guard value - △V _BG2 , calculate from the coefficient n _SR. Subtract the unit digit (e.g. 1) (step 3)
3) When the rate of change △V _B is greater than _nSR subtraction guard value - △V _BG2 , the duty ratio D _F is sufficiently small, so the coefficient n _SR is left as is and the upper limit timer is reset. After that, the program is restarted, the lower limit timer is reset, and the program remains stopped (step 34). Then, the duty ratio D _F is
The correction is made according to the formula: D _F =D _F +n _SR ×a%. Here, the rate of change △V _B of battery voltage V _B is
Obtained as the difference between the previous sampling value and the current sampling value of battery voltage V _B , and the rate of change △
When _VB is smaller than the _nSR subtraction guard value _-vVBG , the coefficient _nSR is decreased and the duty ratio _DF is decreased. In this way, battery voltage V _B is adjusted while preventing battery voltage V _B from dropping excessively.

Here, time series data sampled at a predetermined sampling period is used as the battery voltage V _B.
If V _B n is used, a more accurate battery voltage can be obtained by applying a predetermined smoothing than by setting V _B =V _B n. Therefore, if the smoothed battery voltage is expressed as V _B x, then V _B ×n = αV _B n + (1-α) V _B x (n-1) (0<α≧1), which is the so-called exponential smoothing. can be applied.
The exponentially smoothed battery voltage obtained in this way
If the above control method is executed using V _B x,
This allows for more accurate battery voltage control. Further, the smoothing may be performed by calculating the arithmetic average of the battery voltages V _B during a plurality of samplings.

From the above, it is clear that according to the on-vehicle power generator according to the present invention, the field current of the generator is basically kept constant according to the absolute amount of the applied electrical load by weighting a plurality of electrical loads. Because it is controlled to maintain a continuous amount of This not only improves stability but also prevents battery voltage from rising or falling excessively. In this case, even if the battery voltage exceeds a predetermined upper limit value or falls below a predetermined lower limit value, the power generation amount is not increased or decreased immediately, but only after a predetermined period of time has passed, so the electrical load Since the cycle of changing the duty ratio is longer than the hunting cycle corresponding to the absolute amount of the magnitude of , the engine hunting phenomenon can be prevented. Furthermore, when the rate of increase/decrease in the battery voltage is actually measured and the rate of increase/decrease becomes large, it is configured to issue a command to increase or decrease the field current, thereby preventing an excessive increase or decrease in the battery voltage. This is such that hunting does not decrease unnecessarily as it is obtained.

Further, if the duty control method is adopted, the circuit configuration becomes easy, and heat generation in the control circuit due to continuous current passing can be prevented, which is an advantage. Note that since the period of the duty control pulse signal is considerably shorter than the period of fluctuations in engine speed during hunting, it does not have any adverse effect on hunting.

Furthermore, when the battery voltage exceeds the set maximum value, the field current is forcibly set to zero by the clip circuit 9, which prevents an excessive rise in battery voltage and prevents damage and deterioration of the battery itself and other electrical components. be.

Further, depending on the case, the field current may be controlled by the load signal voltage El not only in the idling operating state but also in other operating states. It goes without saying that the engine parameter for determining the idling state is not limited to the throttle opening θth.

Further, the minimum value and maximum value of the field current are not limited to the duty ratio D _F of 0% and 100%.

In the above embodiment, the control circuit 7 as the field current control means outputs a pulse signal with a predetermined duty ratio ratio _DF , but is not limited to this, and outputs a pulse signal with a load signal voltage El, engine speed Ne, and throttle opening. Needless to say, it is also possible to output an analog voltage corresponding to the degree θth.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a control device for an on-vehicle power generator according to the present invention, FIGS. 2 and 5 are flowcharts showing the operation of the control device in FIG. 1, and FIG. FIG. 4, a graph showing the relationship with the duty ratio, is a circuit diagram showing an example of a load detection circuit that detects the magnitude of the electrical load. Explanation of symbols of main parts, 1...AC generator, 2
... Field coil, 4 ... Battery, 6 ... Electrical load, 7 ... Control circuit, 8 ... Load detection circuit, 9
...Clip control circuit.

Claims (1)

[Claims] 1. Generator 1 powered by a vehicle drive engine
an on-vehicle device comprising: a conversion means for converting the output power of the generator into DC power; and a relay means (SW1 to SW4) for selectively supplying the DC power to a plurality of electrical loads mounted on the vehicle. The power generation apparatus includes a detection means 8 for generating a selection detection signal having a size corresponding to the selection content of the electrical load by the relay means, and a field having a predetermined size according to the selection content detection signal. The field current supply means 7, 9, and Q select a magnetic current value of 1 and supply it to the field coil of the generator, and the field current supply means selects a value of 1 and supplies it to the field coil of the generator. a first adjusting means 21 for increasing the selected field current value by a first predetermined amount when the value falls below the lower limit;
25, 27, 28, and the field current value selected when the voltage of the DC power exceeds a predetermined upper limit value is set as a second field current value.
Second adjustment means 22, 3 for decreasing by a predetermined amount
0, 32, and 33. 2. The field current value is expressed by a pulse voltage duty ratio, the first predetermined amount corresponds to a first predetermined duty ratio change, and the second predetermined amount corresponds to a second predetermined duty ratio change. An on-vehicle power generation device according to claim 1, characterized in that the on-vehicle power generation device corresponds to. 3) increasing the field current by a first predetermined amount or decreasing it by a second predetermined amount; An on-vehicle power generation device according to claim 1 or 2, characterized in that the on-vehicle power generation device 4. The voltage of the DC output is sampled and detected at a predetermined sampling period, and the field current is increased or decreased only when a predetermined number of sampling values consecutively fall below the lower limit value or exceed the upper limit value. Claim No. 3:
The on-vehicle power generation device described in Section 1. 5. The vehicle-mounted power generation device according to claim 4, wherein the average value of the sampling values of the voltage of the DC output is compared with the lower limit value or the upper limit value.