Differential modulation type constant frequency excitation generator voltage regulator with preset bidirectional narrow pulse
Technical Field
The invention belongs to the technical field of automobile generator control, and relates to a differential modulation type fixed-frequency excitation generator voltage regulator with preset bidirectional narrow pulses.
Background
The existing automobile generator can automatically adjust the excitation duty ratio according to the output voltage of the generator when the automobile runs, and the excitation adjusting mode of the voltage regulator of the generator can be divided into the following steps:
excitation with completely non-fixed frequency: the voltage regulator compares the effective equivalent of the output voltage with a set value, and determines whether to switch on excitation or switch off excitation according to the comparison result, so the excitation state is only determined by the output voltage, the excitation frequency is determined by the calculation mode of the effective equivalent of the output voltage, the circuit response time and the like, the excitation frequency can be influenced by the load change of the generator, the connection relation of the storage battery and the like, the change range of some excitation frequencies is larger, for example, the excitation frequency is 20Hz under the condition that the storage battery is only connected with no load, the excitation frequency is increased to 1.8KHz when the storage battery belt 40A load is thrown, the higher frequency increases the loss of a power tube of the regulator, increases the heating, increases the iron loss of the generator, the instability of the excitation frequency increases the electromagnetic resistance change of the generator, and generates larger.
Secondly, non-fixed frequency excitation triggered by fixed frequency: the voltage regulator is internally provided with an oscillating circuit which is triggered to switch on excitation at a fixed frequency, the regulator cuts off the excitation when the output voltage of the generator exceeds a set value, although the excitation is triggered to switch on at the fixed frequency, an excitation control end shows non-fixed frequency excitation, the time difference of starting the excitation each time is integral multiple of the same base number, the excitation control cannot detect a fixed frequency trigger pulse, the excitation waveform of the F point of the excitation control end is very similar to the non-fixed frequency, and the fixed frequency trigger pulse is completely blanked in the overvoltage period of the generator.
③ fixed frequency excitation: the excitation is carried out at a fixed excitation frequency, and the excitation frequency is stable, so that the electromagnetic resistance of the generator is changed uniformly, and the running stability of the engine is improved.
The control mode of the existing constant-frequency excitation voltage regulator comprises the following steps: the triangular wave comparison mode is that an output signal obtained after the output voltage of the generator is sampled is compared with a triangular wave with a certain frequency and equal amplitude to obtain a duty ratio modulation signal, and excitation is controlled by the duty ratio modulation signal.
The chopper type is that excitation is triggered by using a trigger pulse with fixed frequency, the excitation is cut off in overvoltage, the excitation is mostly completed by a complex digital-analog hybrid integrated chip, the circuit structure is complex, and the cost is high.
The two modes can be completed by a single chip microcomputer, but the general single chip microcomputer is prone to failure in the power supply environment of high temperature change, high electromagnetic interference and high surge impact of the generator, such as various program problems and poor temperature resistance; and the single chip microcomputer special for the generator is expensive and has high temperature resistance and high pressure resistance.
Therefore, a constant-frequency excitation voltage regulator with a simple circuit structure needs to be researched.
Disclosure of Invention
In order to solve the fixed-frequency excitation of the technical problem, the invention creatively adopts a differential modulation mode to realize the fixed-frequency excitation.
According to an aspect of the present invention, there is provided a differential modulation type constant frequency excitation generator voltage regulator with preset bidirectional narrow pulses, which is characterized by comprising a sampling unit 1000, a reference unit 1001, a comparison unit 1002, a narrow pulse generation unit 1003, a coupling capacitor C0, a power unit 1004 and a freewheeling unit 1005, wherein:
the sampling unit 1000 is connected to the positive electrode and the negative electrode of the voltage regulator, the reference unit 1001 outputs a reference voltage value, the comparison unit is a voltage comparator with two input ends, the output end of the sampling unit 1000 is connected to the second input end of the comparison unit 1002, the narrow pulse generation unit 1003 is connected to the second input end of the comparison unit 1002 through a coupling capacitor C0, the first input end of the comparison unit 1002 is connected to the reference unit 1001, the output end of the comparison unit 1002 is connected to the input end of the power unit 1004, the freewheel unit 1005 is connected between the output end of the power unit 1004 and the positive electrode of the power supply, the negative electrode of the power unit 1004 is grounded, and the output end of the power unit 1004 is used for connecting to the excitation winding and controlling the excitation current.
According to the second aspect of the present invention, there is provided a differential modulation type constant frequency excitation generator voltage regulator with preset bidirectional narrow pulses, which is characterized by comprising a sampling unit 1000, a reference unit 1001, an amplifying unit 1002, a narrow pulse generating unit 1003, a coupling capacitor C0, a power unit 1004 and a freewheeling unit 1005, wherein:
the sampling unit 1000 is connected to the positive and negative electrodes of the voltage regulator, the reference unit 1001 is a zener diode, the amplifying unit 1002 is a single-ended input and single-ended output amplifying circuit, the output end of the sampling unit 1000 is connected to the input end of the amplifying unit 1002 through the reference unit 1001, the narrow pulse generating unit 1003 is connected to the input end of the reference unit 1001 through a coupling capacitor C0, the output end of the amplifying unit 1002 is connected to the input end of the power unit 1004, the freewheeling unit 1005 is connected between the output end of the power unit 1004 and the positive electrode of the power supply, the negative electrode of the power unit 1004 is grounded, and the output end of the power unit 1004 is used for connecting to the excitation winding and controlling the excitation current.
The invention has the beneficial effects that: the voltage regulator realizes a fixed-frequency excitation function by adopting a differential modulation mode of preset bidirectional narrow pulses, has accurate triggering, accurate regulation of the output voltage of the generator and strong stability, and has the advantages of simple circuit structure, easy realization, reliable performance, lower cost and easy popularization.
Drawings
Fig. 1 is a schematic circuit diagram of a differential modulation type constant frequency excitation generator voltage regulator for presetting bidirectional narrow pulses according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of another differential modulation type constant-frequency excitation generator voltage regulator with preset bidirectional narrow pulses according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a circuit waveform of a voltage regulator of a preset bidirectional narrow-pulse differential modulation type fixed-frequency excitation generator according to an embodiment of the present invention;
fig. 4 is a schematic circuit waveform diagram of a preset bidirectional narrow-pulse differential modulation type constant-frequency excitation generator voltage regulator according to an embodiment of the invention.
Detailed Description
According to the design idea of the invention, a differential modulation type constant-frequency excitation generator voltage regulator with preset bidirectional narrow pulses is designed by adopting a small number of elements.
In a first aspect, an embodiment of the present invention provides a differential modulation type constant frequency excitation generator voltage regulator with preset bidirectional narrow pulses.
Example 1
As shown in fig. 1, the voltage regulator for the preset bidirectional narrow-pulse differential modulation type fixed-frequency excitation generator includes a sampling unit 1000, a reference unit 1001, a comparison unit 1002, a narrow-pulse generation unit 1003, a coupling capacitor C0, a power unit 1004, and a freewheeling unit 1005, where:
the sampling unit 1000 is connected with the positive electrode and the negative electrode of the voltage regulator and used for sampling the output voltage of the generator, the reference unit 1001 is a voltage stabilizing circuit and provides a reference voltage value for the comparison unit 1002, the comparison unit is a voltage comparator with two input ends, the output end of the sampling unit 1000 is connected with the second input end of the comparison unit 1002, the narrow pulse generation unit 1003 is connected with the second input end of the comparison unit 1002 through a coupling capacitor C0, the first input end of the comparison unit 1002 is connected with the reference unit 1001, the output end of the comparison unit 1002 is connected with the input end of the power unit 1004, the follow current unit 1005 is connected between the output end of the power unit 1004 and the positive electrode of a power supply, the negative electrode of the power unit 1004 is grounded, and the output end of the.
The working process of the circuit is as follows:
the narrow pulse generating unit 1003 continuously outputs narrow pulses, see curve a in fig. 3, and the narrow pulse width can be set according to the need when the narrow pulse generating unit 1003 is designed, and is generally recommended to be between 0.5% and 2%. The narrow pulse is coupled to a first input of the comparing unit 1002 through a coupling capacitor C0. As the narrow pulse charges and discharges the capacitor C0, a "bidirectional narrow pulse" is obtained at the first input terminal of the comparing unit 1002, that is: the narrow pulse rising edge charges C0 and the narrow pulse falling edge discharges and reversely charges C0, the waveform of the "bidirectional narrow pulse" is as shown in curve B in fig. 3, it is obvious that the capacitor C0 and the effective resistance of the sampling unit form an RC differentiating circuit, and the obtained "bidirectional narrow pulse" is obtained by differentiating the narrow pulse output by the narrow pulse generating unit 1003: at time t1, the rising edge of the narrow pulse of the a curve comes to charge C0, and a narrow pulse type charging waveform that rises on the B curve is obtained, and at time t2, the rising edge of the narrow pulse of the a curve comes to discharge and reverse charge C0, and a narrow pulse type waveform that falls on the B curve is obtained.
Assuming the coupling capacitance C0 is open: when the output voltage of the generator is lower than a set value, the output signal voltage of the sampling unit 1000 is lower than the output voltage of the reference unit 1001, the comparator 1002 outputs a first level, and the first level controls the output terminal of the power unit 1004 to be conducted to the ground to switch on the exciting current; when the generator output voltage is higher than the set value, the output signal voltage of the sampling unit 1000 is higher than the output voltage of the reference unit 1001, and the comparator 1002 outputs a second level, wherein the first level controls the output end of the power unit 1004 to be grounded and cut off the excitation current. This is the operating principle of a common voltage regulator.
Now turning on C0, a high-low bi-level narrow pulse is added to the input of comparator 1002, whose electronic waveform is shown in curve B of fig. 3, which modulates the sampling cell output signal, at time t 2: whether the output voltage of the generator is lower than a set value or not, the signal voltage modulated by the narrow pulse of the low level is lower than the output voltage of the reference unit 1001 during the narrow pulse period, so that the exciting current is switched on; at time t 3: regardless of whether the generator output voltage is higher than the set value, the high-level narrow-pulse modulated signal voltage is higher than the output voltage of the reference unit 1001 during the narrow pulse, so that the excitation current is cut off, and a D-curve waveform voltage as shown in fig. 3 is obtained at the input terminal of the power unit 1004.
Therefore, by reasonably setting the narrow pulse frequency, for example, selecting a fixed frequency within the range of 120-350 Hz, practice proves that the generator can be excited at the narrow pulse frequency, which is equivalent to the principle that a mechanical device is subjected to vibration of an external natural frequency to be forced vibration.
When the generator is continuously under-voltage due to low speed or overload, etc., due to the existence of the "high level" of the narrow pulse (e.g., the narrow pulse starting at t1 or t 3), a power tube cut-off narrow pulse occurs in the excitation loop, as shown by curve E in fig. 3. Because the duty ratio of the narrow pulse is extremely low (generally 0.5-2%), the restriction effect on full excitation is extremely small and can be generally ignored.
When the generator is continuously over-pressurized, a power tube conduction narrow pulse occurs in the excitation loop due to the presence of a "low" level of narrow pulses (e.g., a narrow pulse starting at t2 or t 4), as shown by curve F in fig. 3. The duty ratio of the narrow pulse is extremely low (generally 0.5-2%), so that the excitation of the generator is not influenced when the voltage is over-voltage, the narrow pulse which is still fixedly conducted when most of foreign constant-frequency excitation voltage regulators are over-voltage is generally 2-8% (also called as residual pulse), and the duty ratio of the residual pulse is low, so that the voltage output by the generator due to the residual pulse is still lower than a set value. The residual pulse of the technical scheme of the invention has lower duty ratio.
The excitation loop has a cut-off narrow pulse with high level or a turn-on narrow pulse with low level no matter in the continuous undervoltage or overvoltage period, so the excitation loop is called as a preset bidirectional narrow pulse.
The C-curve in fig. 3 is the horizontal axis of the coordinates of the entire fig. 3, and represents the time parameter.
The freewheel unit 1005 is a freewheel diode, which is a well-known technology and will not be described herein.
The effect of the embodiment is: the voltage regulator realizes a fixed-frequency excitation function by adopting a differential modulation mode of preset bidirectional narrow pulses, has accurate triggering, accurate regulation of the output voltage of the generator and strong stability, particularly when the output voltage of the generator is higher than a set value, a sampling output signal is modulated by the fixed-frequency narrow pulses in time, and the excitation current is cut off in time, so that the problem of secondary delay is effectively avoided, the reliability of the voltage regulator in the technical scheme of the invention is obviously improved, and C0 also serves as a sampling signal filter capacitor.
In a second aspect, the embodiment of the invention further provides a differential modulation type fixed-frequency excitation generator voltage regulator for presetting the bidirectional narrow pulse.
Example 2
As shown in fig. 2, the voltage regulator for the preset bidirectional narrow-pulse differential modulation type fixed-frequency excitation generator includes a sampling unit 1000, a reference unit 1001, an amplifying unit 1002, a narrow-pulse generating unit 1003, a coupling capacitor C0, a power unit 1004, and a freewheeling unit 1005, where:
the sampling unit 1000 is connected to the positive electrode and the negative electrode of the voltage regulator, the reference unit 1001 is a zener diode, the amplifying unit 1002 is a single-ended input and single-ended output amplifying circuit, such as a triode amplifying circuit, the output end of the sampling unit 1000 is connected to the input end of the reference unit 1001, the output end of the reference unit 1001 is connected to the input end of the amplifying unit 1002, the narrow pulse generating unit 1003 is connected to the input end of the reference unit 1001 through a coupling capacitor C0, the output end of the amplifying unit 1002 is connected to the input end of the power unit 1004, the freewheeling unit 1005 is connected between the output end of the power unit 1004 and the positive electrode of the power supply, the negative electrode of the power unit 1004 is grounded, and the output end.
The working process of the circuit is as follows:
the narrow pulse generating unit 1003 continuously outputs the same narrow pulse as in embodiment 1.
Assuming the coupling capacitance C0 is open: when the output voltage of the generator is lower than a set value, the output signal voltage of the sampling unit 1000 is lower than the conduction threshold voltage of the reference unit 1002, the amplifying unit 1002 outputs a first level, and the first level controls the output end of the power unit 1004 to be conducted to the ground to be connected so as to excite the current; when the generator output voltage is higher than the set value, the output signal voltage of the sampling unit 1000 is higher than the turn-on threshold voltage of the reference unit 1001, causing the amplifying unit 1002 to output a second level that controls the output terminal of the power unit 1004 to be turned off to ground to cut off the excitation current. This is also the operating principle of a common voltage regulator.
Now turning on C0, a high-low bi-level narrow pulse is added to the input of reference cell 1001, which modulates the sampling cell output signal, at time t 2: whether the output voltage of the generator is lower than a set value or not, the signal voltage modulated by the narrow pulse of the low level is lower than the conduction threshold voltage of the reference unit 1001 during the narrow pulse period, so that the exciting current is switched on; at time t 3: regardless of whether the generator output voltage is higher than the set value, the signal voltage after the high level narrow pulse modulation is higher than the on threshold voltage of the reference unit 1001 during the narrow pulse period, so that the exciting current is cut off, and a D-curve waveform voltage as shown in fig. 3 is obtained at the input terminal of the power unit 1004.
Therefore, by reasonably setting the narrow pulse frequency, for example, selecting a fixed frequency within the range of 120-350 Hz, practice proves that the generator can be excited at the narrow pulse frequency, which is equivalent to the principle that a mechanical device is subjected to vibration of an external natural frequency to be forced vibration.
When the generator is continuously under-voltage due to low speed or overload, etc., due to the existence of the "high level" of the narrow pulse (e.g., the narrow pulse starting at t1 or t 3), a power tube cut-off narrow pulse occurs in the excitation loop, as shown by curve E in fig. 3. Because the duty ratio of the narrow pulse is extremely low (generally 0.5-2%), the restriction effect on full excitation is extremely small and can be generally ignored.
When the generator is continuously over-pressurized, a power tube conduction narrow pulse occurs in the excitation loop due to the presence of a "low" level of narrow pulses (e.g., a narrow pulse starting at t2 or t 4), as shown by curve F in fig. 3. The duty ratio of the narrow pulse is extremely low (generally 0.5-2%), so that the excitation of the generator is not influenced when the voltage is over-voltage, the narrow pulse which is still fixedly conducted when most of foreign constant-frequency excitation voltage regulators are over-voltage is generally 2-8% (also called as residual pulse), and the duty ratio of the residual pulse is low, so that the voltage output by the generator due to the residual pulse is still lower than a set value. The residual pulse of the technical scheme of the invention has lower duty ratio.
The C-curve in fig. 3 is the horizontal axis of the coordinates of the entire fig. 3, and represents the time parameter.
The freewheel unit 1005 is a freewheel diode, which is a well-known technology and will not be described herein.
By way of illustration of the above embodiments, it can be seen that: as shown in fig. 4, the excitation control waveform (curve G in fig. 4) at the output end of the power unit 1004, which is obtained by performing differential modulation on the sampling signal by the fixed-frequency narrow pulse through the coupling capacitor C0, is good in fixed-frequency effect, and is controlled at a fixed frequency when a load is changed or a battery is thrown.
The technical scheme of the invention has the beneficial effects that: the voltage regulator realizes a fixed-frequency excitation function by adopting a differential modulation mode of preset bidirectional narrow pulses, has accurate triggering, accurate regulation of the output voltage of the generator and strong stability, particularly when the output voltage of the generator is higher than a set value, a sampling output signal is modulated by the fixed-frequency narrow pulses in time, and the excitation current is cut off in time, so that the problem of secondary delay is effectively avoided, the reliability of the voltage regulator in the technical scheme of the invention is obviously improved, and C0 also serves as a sampling signal filter capacitor. The circuit of the invention has simple structure, easy realization, reliable performance, lower cost and easy popularization.
The embodiments of the present invention are only used for illustrating the technical solutions of the present invention, and are not limited to the present invention, and other embodiments or other combinations obtained by equivalent substitution and non-inventive work fall within the scope of the present invention, which is defined by the claims.