CN111464155B - Sawtooth wave generating circuit - Google Patents
Sawtooth wave generating circuit Download PDFInfo
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- CN111464155B CN111464155B CN202010206504.4A CN202010206504A CN111464155B CN 111464155 B CN111464155 B CN 111464155B CN 202010206504 A CN202010206504 A CN 202010206504A CN 111464155 B CN111464155 B CN 111464155B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K4/00—Generating pulses having essentially a finite slope or stepped portions
- H03K4/06—Generating pulses having essentially a finite slope or stepped portions having triangular shape
- H03K4/08—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape
- H03K4/48—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements semiconductor devices
- H03K4/50—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements semiconductor devices in which a sawtooth voltage is produced across a capacitor
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
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Abstract
The invention is applicable to the technical field of circuit control, and provides a sawtooth wave generating circuit, which comprises: the input end of the control switch unit inputs the mains voltage, the output end of the control switch unit, the input end of the sawtooth wave generating unit and the input end of the constant current source unit are connected together, and the control switch unit is used for controlling the on and off of the constant current source unit according to the mains voltage; the input end of the constant current source unit is also input with a first preset voltage, and the output end of the constant current source unit is connected with the input end of the constant current source unit; the sawtooth wave generating unit is used for controlling the current output by the constant current source unit through the control switch unit to generate sawtooth waves which are synchronous with the mains voltage and can update the slope along with the mains frequency in real time, so that the problem that the corresponding driving signals generated by the sawtooth waves in the prior art cannot be adjusted correspondingly along with the change of the mains frequency in real time, and the driving signals are unreliable is solved.
Description
Technical Field
The invention belongs to the technical field of circuit control, and particularly relates to a sawtooth wave generating circuit.
Background
The conventional sawtooth wave generating circuit can be evolved by a triangular wave generating circuit, the triangular wave generating circuit can comprise a non-inverting input hysteresis comparator and an integral operation circuit, when the output of the hysteresis comparator is at a high level, the voltage charges a capacitor in an integrator, the output voltage of the integrator formed by the integral operation circuit is linearly reduced, when the output of the hysteresis comparator is at a low level, the voltage discharges the capacitor in the integrator, and the output voltage of the integrator is linearly increased, so that the output voltage of the integrator is a triangular wave. By changing the time constant of the forward and backward integration of the integrator, the rising and falling slopes of the integrator output voltage are different, so that a sawtooth voltage can be obtained.
However, the conventional sawtooth wave generating circuit cannot realize that the slope and amplitude voltage of the sawtooth wave are correspondingly adjusted along with the periodic variation of the mains supply, so that the corresponding driving signal generated based on the sawtooth wave cannot be correspondingly adjusted along with the variation of the mains frequency in real time, and the driving signal is unreliable.
Disclosure of Invention
In view of the above, an embodiment of the present invention provides a sawtooth wave generating circuit, so as to solve the problem that in the prior art, the slope and the amplitude voltage of a sawtooth wave cannot be adjusted correspondingly due to the periodic variation of the sawtooth wave along with the mains supply, so that a driving signal cannot be adjusted correspondingly due to the fact that a driving signal generated based on the sawtooth wave cannot be adjusted correspondingly due to the periodic variation of the mains supply frequency in real time, and the driving signal is unreliable.
A first aspect of an embodiment of the present invention provides a sawtooth wave generating circuit, including: a control switch unit, a constant current source unit and a sawtooth wave generating unit;
the input end of the control switch unit inputs the mains voltage, the output end of the control switch unit, the input end of the sawtooth wave generating unit and the input end of the constant current source unit are connected together, and the control switch unit is used for controlling the on and off of the constant current source unit according to the mains voltage;
the input end of the constant current source unit is also input with a first preset voltage, the output end of the constant current source unit is connected with the input end of the constant current source unit, and the constant current source unit is used for converting the input first preset voltage into stable current and inputting the stable current into the sawtooth wave generating unit;
the sawtooth wave generating unit is used for controlling the current output by the constant current source unit through the control switch unit to generate sawtooth waves which are synchronous with the mains voltage and can update the slope and the amplitude in real time along with the mains frequency.
In an embodiment, the control switch unit comprises a control subunit and a switch subunit;
the input end of the control subunit is the input end of the control switch unit, the output end of the control subunit is connected with the input end of the switch subunit, and the output end of the switch subunit is the output end of the control switch unit.
In an embodiment, the control subunit comprises: diode D1, diode D2, resistor R1, and capacitor C1;
one end of the resistor R1 is connected with a power supply of a second preset voltage, and the other end of the resistor R1 is respectively connected with the anode of the diode D1, the anode of the diode D2 and one end of the capacitor C1;
the mains voltage input by the cathode of the diode D1;
the negative electrode of the diode D2 is the output end of the control subunit;
the other end of the capacitor C1 is grounded.
In an embodiment, the switching subunit comprises: transistor Q1 and resistor R2;
the base electrode of the triode Q1 is connected with the output end of the control subunit, the collector electrode of the triode Q1 is connected with one end of the resistor R2, and the emitter electrode of the triode Q1 is grounded;
the other end of the resistor R2 is the output end of the switch subunit.
In an embodiment, the constant current source unit includes: the operational amplifier U1, the resistor R3, the resistor R4, the resistor R5, the damping capacitor C2 and the damping capacitor C3;
the non-inverting input end of the operational amplifier U1 is the input end of the constant current source unit;
the output end of the operational amplifier U1 is respectively connected with one end of the resistor R3, one end of the resistor R4, one end of the damping capacitor C2 and one end of the damping capacitor C3; the other end of the resistor R3 and the other end of the damping capacitor C2 are connected with the non-inverting input end of the operational amplifier U1; the other end of the resistor R4 and the other end of the damping capacitor C3 are respectively connected with the inverting input end of the operational amplifier U1 and one end of the resistor R5, and the other end of the resistor R5 is grounded.
In one embodiment, the sawtooth wave generating unit includes a capacitor C4;
one end of the capacitor C4 is used as an input end of the sawtooth wave generating unit, the other end of the capacitor C4 is grounded, and the capacitor C4 is used for generating sawtooth waves which are synchronous with the mains voltage and can update the slope and the amplitude in real time along with the mains frequency.
In an embodiment, further comprising: a frequency-voltage conversion unit;
the input end of the frequency-voltage conversion unit inputs the mains frequency, and the output end of the frequency-voltage conversion unit is connected with the input end of the constant current source unit and is used for inputting the first preset voltage for the constant current source unit.
In an embodiment, further comprising: a follower unit and/or an amplifier unit;
when only the following unit is further included, the input end of the following unit inputs the first preset voltage or is connected with the output end of the frequency voltage conversion unit, and the output end of the following unit is connected with the input end of the constant current source unit;
when the constant current source unit only comprises an amplifying unit, the input end of the amplifying unit inputs the first preset voltage or is connected with the output end of the frequency voltage conversion unit, and the output end of the following unit is connected with the input end of the constant current source unit;
when the frequency-voltage conversion unit is further arranged, the input end of the following unit inputs the first preset voltage or is connected with the output end of the frequency-voltage conversion unit, and the output end of the following unit is connected with the input end of the amplifying unit; the output end of the amplifying unit is connected with the input end of the constant current source unit.
In an embodiment, the follower unit comprises: an operational amplifier U2;
the non-inverting input end of the operational amplifier U2 is the input end of the following unit; the inverting input end of the operational amplifier U2 is connected with the output end of the operational amplifier U2, and the output end of the operational amplifier U2 is the output end of the following unit;
the amplifying unit includes: an operational amplifier U3, a resistor R7 and a resistor R8;
one end of the resistor R7 is an input end of the amplifying unit, and the other end of the resistor R7 is respectively connected with one end of the resistor R8 and an inverted input end of the operational amplifier U1;
the non-inverting input end of the operational amplifier U1 is grounded, and the output end of the operational amplifier U1 is connected with the other end of the R8 and serves as the output end of the amplifying unit.
In an embodiment, further comprising: a frequency multiplication unit;
the input end of the frequency multiplication unit inputs the mains frequency, and the output end of the frequency multiplication unit is connected with the input end of the frequency voltage conversion unit and is used for amplifying the mains period by a preset multiple through the phase-locked chip and the counter.
Compared with the prior art, the embodiment of the invention has the beneficial effects that: and the sawtooth wave generating unit and the constant current source unit are controlled to be turned on and off by the mains voltage through inputting the mains voltage at the input end of the control switch unit. When the mains voltage is in the positive half axis of the corresponding sine wave, the control switch unit is turned on, which is equivalent to cutting off the constant current source unit, so that the constant current source unit is turned off, and the sawtooth wave generating unit discharges through the control switch unit. When the mains voltage is in the negative half axis of the corresponding sine wave, the control switch unit is closed, the stable current generated by the first preset voltage input constant current source unit is input into the sawtooth wave generating unit, so that the sawtooth wave generating unit charges until the mains voltage is in the positive half axis of the corresponding sine wave, the control switch unit is conducted, the sawtooth wave generating unit discharges through the control switch unit, the sawtooth wave is generated along with the periodic transformation of the mains voltage, and the generated sawtooth wave is synchronous with the mains voltage and can update the slope and the amplitude in real time along with the change of the frequency of the first preset voltage.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a sawtooth wave generating circuit according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a control switch unit according to another embodiment of the present invention;
fig. 3 is a schematic circuit diagram of a constant current source unit and a sawtooth wave generating unit according to an embodiment of the present invention;
fig. 4 is a circuit example diagram of a frequency-to-voltage conversion unit according to an embodiment of the present invention;
FIG. 5 is a schematic circuit diagram of a frequency multiplier unit according to an embodiment of the present invention;
fig. 6 is a schematic circuit diagram of a sawtooth wave generating circuit according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to illustrate the technical scheme of the invention, the following description is made by specific examples.
Fig. 1 is a schematic diagram of a sawtooth wave generating circuit according to an embodiment of the present invention, which is described in detail below. As shown in fig. 1, the sawtooth wave generating circuit includes a control switch unit 101, a constant current source unit 102, and a sawtooth wave generating unit 103.
The input end of the control switch unit 101 inputs a mains voltage, the output end of the control switch unit 101, the input end of the sawtooth wave generating unit 103 and the input end of the constant current source unit 102 are connected together, and the control switch unit 101 is used for controlling the on and off of the constant current source unit 102 according to the mains voltage;
the input end of the constant current source unit 102 is further input with a first preset voltage, the output end of the constant current source unit 102 is connected with the input end of the constant current source unit 102, and the constant current source unit 102 is used for converting the input first preset voltage into a stable current and inputting the stable current into the sawtooth wave generating unit 103;
the sawtooth wave generating unit 103 is configured to control the current output by the constant current source unit 102 through the control switch unit 101, and generate a sawtooth wave that is synchronous with the mains voltage and can update the slope and amplitude in real time with the mains frequency.
In the sawtooth wave generating circuit, the input end of the control switch unit is input with the mains voltage, and the on and off of the sawtooth wave generating unit and the constant current source unit are controlled by the mains voltage. When the mains voltage is in the positive half axis of the corresponding sine wave, the control switch unit is turned on, which is equivalent to the short circuit of the constant current source unit, so that the constant current source unit is turned off, and the sawtooth wave generating unit discharges through the control switch unit. When the mains voltage is in the negative half axis of the corresponding sine wave, the control switch unit is closed, the stable current generated by the first preset voltage input constant current source unit is input into the sawtooth wave generating unit, so that the sawtooth wave generating unit charges until the mains voltage is in the positive half axis of the corresponding sine wave, the control switch unit is conducted, the sawtooth wave generating unit discharges through the control switch unit, the sawtooth wave is generated along with the periodic transformation of the mains voltage, and the generated sawtooth wave is synchronous with the mains voltage and can update the slope and the amplitude in real time along with the change of the frequency of the first preset voltage.
Optionally, as shown in fig. 2, the control switch unit 101 includes a control subunit 1011 and a switch subunit 1012;
the input end of the control subunit 1011 is the input end of the control switch unit, that is, the input mains voltage, the output end of the control subunit 1011 is connected to the input end of the switch subunit 1012, and the output end of the switch subunit 1012 is the output end of the control switch unit 101.
Optionally, as shown in fig. 2, the control subunit 1011 includes a diode D1, a diode D2, a resistor R1, and a capacitor C1.
One end of the resistor R1 is connected with a power supply of a second preset voltage, and the other end of the resistor R1 is respectively connected with the anode of the diode D1, the anode of the diode D2 and one end of the capacitor C1; alternatively, the power source of the second preset voltage may be a power source of 15V.
The mains voltage input by the cathode of the diode D1;
the negative electrode of the diode D2 is the output end of the control subunit;
the other end of the capacitor C1 is grounded.
Optionally, the control subunit 1011 may further be connected in series with a resistor between one end of the resistor R1 and the first preset voltage input port, or connected in series with another resistor R1 at a connection point between the anode of the diode D1 and the anode of the diode D2, so as to achieve the voltage drop target.
Optionally, as shown in fig. 2, the switch subunit 1012 includes: transistor Q1 and resistor R2;
the base electrode of the triode Q1 is connected with the output end of the control subunit, the collector electrode of the triode Q1 is connected with one end of the resistor R2, and the emitter electrode of the triode Q1 is grounded;
the other end of the resistor R2 is the output of the switch subunit 1012.
In fig. 2, when the mains voltage is in the positive half-axis of the corresponding sine wave, the diode D1 is not conductive, and the diode D2 is conductive by the power source of the second preset voltage, so that the triode Q1 is conductive. Alternatively, the resistance of R2 is 1K. The output end of the control switch unit is connected with the input end of the constant current source unit, at the moment, the resistance value of the resistor R2 is smaller, which is equivalent to the direct short circuit constant current source unit, namely the constant current source unit is turned off, so that the sawtooth wave generating unit discharges through the resistor R2.
When the mains voltage is in the negative half axis of the corresponding sine wave, the diode D1 is turned on, the diode D2 is turned off, the triode Q1 is turned off, which is equivalent to the turning off of the control switch unit, and the stable current generated by the first preset voltage input constant current source unit is input into the sawtooth wave generating unit, so that the sawtooth wave generating unit charges. Thus, the sawtooth wave generating unit is continuously charged and discharged along with the period of the mains voltage, so that sawtooth waves are generated, the generated sawtooth waves are synchronous with the mains voltage, and the slope and the amplitude can be updated in real time along with the change of the frequency of the first preset voltage.
As shown in fig. 3, the constant current source unit 102 may include: the operational amplifier U1, the resistor R3, the resistor R4, the resistor R5, the damping capacitor C2 and the damping capacitor C3.
The non-inverting input end of the operational amplifier U1 is the input end of the constant current source unit, namely, a first preset voltage is input;
the output end of the operational amplifier U1 is respectively connected with one end of the resistor R3, one end of the resistor R4, one end of the damping capacitor C2 and one end of the damping capacitor C3; the other end of the resistor R3 and the other end of the damping capacitor C2 are connected with the non-inverting input end of the operational amplifier U1; the other end of the resistor R4 and the other end of the damping capacitor C3 are respectively connected with the inverting input end of the operational amplifier U1 and one end of the resistor R5, and the other end of the resistor R5 is grounded.
Optionally, the resistance of the resistor R3 is smaller than the resistance of the resistor R5. When the voltage exists at the non-inverting input end of the operational amplifier U1, the current output by the output end returns to the non-inverting input end through a parallel circuit formed by the resistor R3 and the capacitor C2 to form constant current.
Optionally, the constant current source unit may further include a resistor R6, one end of the resistor R6 is connected to the input end of the control switch unit, the other end of the resistor R6 is connected to the input end of the constant current source unit, and the resistor R6 is used for limiting the current entering the constant current source unit.
Alternatively, as shown in fig. 3, the sawtooth wave generating unit 103 includes a capacitor C4.
One end of the capacitor C4 is used as an input end of the sawtooth wave generating unit and is respectively connected with an output end of the control switch unit and an input end of the constant current source unit, the other end of the capacitor C4 is grounded, and sawtooth waves which are synchronous with the mains voltage and can update the slope and the amplitude in real time along with the mains frequency are generated on the capacitor C4.
Optionally, as shown in fig. 4, the sawtooth wave generating circuit further includes: a frequency-voltage conversion unit 104;
the input end of the frequency-voltage conversion unit 104 inputs the mains frequency, and the output end of the frequency-voltage conversion unit 104 is connected to the input end of the constant current source unit 102, so as to input the first preset voltage to the constant current source unit 102.
As shown in fig. 4, the frequency-voltage conversion unit 104 includes a frequency-voltage conversion chip, an operational amplifier U4, and a connection circuit between the frequency-voltage conversion chip and the operational amplifier U4.
The comparator inverting input end (namely THRS end) of the frequency-voltage conversion chip is connected with the input mains frequency. Optionally, one end of a capacitor C5 may be further connected between the mains frequency input interface and the comparator inverting input end (i.e. THRS end) of the frequency-voltage conversion chip, the other end of the capacitor C5 is respectively connected to the resistor R9, the positive electrode of the diode D3, and the negative electrode of the diode D4, the other end of the resistor R9 and the negative electrode of the diode D3 are connected to a 15V voltage, and the positive electrode of the diode D4 is grounded.
The timing comparison input end (namely the R/Ct end) of the frequency-voltage conversion chip is connected with one end of a capacitor C6 and one end of a resistor R10, the other end of the capacitor C6 is grounded, the other end of the resistor R10 is connected with a preset power supply, and the preset power supply is a 15V power supply. Optionally, two capacitors may be connected in parallel to two ends of the capacitor C6, and a resistor may be connected in series between the resistor R10 and the preset power supply.
The non-inverting input end (namely the com_in end) of the comparator of the frequency-voltage conversion chip is respectively connected with one end of a resistor R11 and one end of a resistor R12, the other end of the resistor R12 is grounded, and the other end of the resistor R11 is connected with the preset power supply. Optionally, one end of the capacitor C7 may be further connected between the resistor R11 and a preset power source, and the other end of the capacitor C7 is grounded. Optionally, the preset power supply is a 15V power supply.
The positive power terminal (i.e., VCC terminal) of the frequency-to-voltage conversion chip is connected between the resistor R11 and a predetermined power supply.
The frequency output end (namely FRE_OUT end) of the frequency-voltage conversion chip is connected with the power supply negative end (namely GND end) of the frequency-voltage conversion chip and then grounded, the current output end (namely OUT end) of the frequency-voltage conversion chip is respectively connected with one end of a capacitor C8, one end of a resistor R13, one end of a resistor R14 and one end of a resistor R15, the other end of the capacitor C8 and the other end of the resistor R15 are grounded, the other end of the resistor R13 is connected with the inverting input end of an operational amplifier U4, the other end of the resistor R14 is connected with the output end of the operational amplifier U4, the non-inverting input end of the operational amplifier U4 is grounded, and one end of a capacitor C9 is respectively connected between the inverting input end and the output end of the operational amplifier U4. The operational amplifier U4, the resistor R13 and the resistor R14 form a constant current source circuit. Optionally, a plurality of capacitors may be connected in parallel to the two ends of the capacitor C9, so as to achieve a constant effect on the current output by the current output end of the frequency-voltage conversion chip.
In fig. 4, the mains frequency signal is input to the comparator inverting input of the frequency-to-voltage conversion chip. When the falling edge of the mains frequency signal comes, the falling edge is compared with the potential of the non-inverting input end of the comparator to output a high level, an internal trigger of the frequency-voltage conversion chip is set, a constant current source (namely a circuit formed by the operational amplifier U4, surrounding resistors and capacitors) in the internal trigger charges the capacitor C8, and meanwhile, the power supply VCC charges the capacitor C7 through the R11. When the voltage on the capacitor C8 is larger than 2VCC/3, the trigger in the frequency-voltage conversion chip is reset, C8 discharges through R15, and meanwhile the capacitor C7 is rapidly discharged at regular time, so that a charging and discharging process is completed. After that, the above working process is repeated by the circuit formed by the frequency-voltage conversion chip and the operational amplifier after each charge-discharge process, so that the frequency/voltage conversion is realized.
Optionally, in order to improve the conversion accuracy of the frequency-voltage conversion chip, the frequency of the mains supply may be amplified by a frequency multiplication unit, that is, the sawtooth wave generating circuit, and further includes a frequency multiplication unit 105, where the mains supply frequency is input to an input end of the frequency multiplication unit 105, and an output end of the frequency multiplication unit 105 is connected to an input end of the frequency-voltage conversion unit 104, so as to amplify the period of the mains supply by a preset multiple through a phase-locked chip and a counter. For example, in this embodiment, the phase-locked chip and the counter can amplify the mains frequency by 100 times, and then convert the input mains frequency into the corresponding real-time voltage through the frequency-voltage conversion unit.
Alternatively, as shown in fig. 5, the frequency doubling unit 105 may include: the phase-locked chip, the shift counter and a connecting circuit between the phase-locked chip and the shift counter.
The signal input end of the phase-locked chip inputs a mains frequency signal. For filtering, a capacitor may be connected, with the other end of the capacitor being grounded.
The comparison signal input end of the phase-locked chip is connected with the resistor R14 in series and then is connected with the output end Q4B of the shift counter. The output end of the voltage-controlled oscillator of the phase-locked chip is respectively connected with the clock input end of the shift counter, and optionally, the output end of the voltage-controlled oscillator of the phase-locked chip is the output end of the frequency doubling unit 105, and is also connected with one end of a parallel circuit formed by the resistor R15 and the capacitor C10, and the other end of the parallel circuit is grounded. And a parallel capacitor is connected between two external oscillating capacitor ends of the phase-locked chip. The negative electrode of the phase-locked chip is grounded, the positive electrode of the phase-locked chip is connected with a power supply with preset voltage, and the optional power supply with preset voltage can be a 15V power supply. The control end of the voltage-controlled oscillator of the phase-locked chip is respectively connected with one end of a capacitor C11, one end of a resistor R16 and one end of a resistor R17, the other end of the resistor R16 is respectively connected with one ends of a capacitor C12 and a capacitor C13, the other ends of the capacitor C11, the capacitor C12 and the capacitor C13 are grounded, the other end of the resistor R17 is connected with the output end of the phase comparator of the phase-locked chip in series with a resistor R18, one end of a capacitor C14 is further connected between the resistor R18 and the resistor R17, and the other end of the capacitor C14 is grounded.
The output end Q4A of the shift counter is respectively connected with the counting permission control end of the shift counter and one end of a resistor R19, and the other end of the resistor R19 is connected between the resistor R14 and the comparison signal input end of the phase-locked chip. The clearing end A, the power supply negative end, the clock input end and the clearing end B of the shift counter are grounded, and the power supply positive end and the technology permission control end of the shift counter chip are connected with a power supply with preset voltage. Alternatively, the power source of the preset voltage may be a 15V power source.
Optionally, the frequency multiplication unit 105 compares the level of the signal input end of the phase-locked chip with the level of the signal input end of the comparison signal input end, when the frequency of the signal input end input signal is lower than that of the comparison signal input end, the output end of the phase comparator II of the phase-locked chip outputs logic "0", otherwise outputs logic "1". The output end of the voltage-controlled oscillator of the phase-locked chip is related to the level states of the signals of the two input ends of the signal input end and the signal input end of the comparison signal input end, when the level states of the signals of the two input ends are the same, the output of the output end of the voltage-controlled oscillator is high level, and when the level states of the signals of the two input ends are different, the output of the output end of the voltage-controlled oscillator is low level. The output level of the voltage-controlled oscillator is fed back to the shift counter, 100 times frequency division can be realized through the connection relation of the output end Q4A, the counting permission control end and the output end Q4B on the shift counter, the input end fed back to the phase-locked chip is 100 times frequency multiplication, the phase difference between the two input frequencies is 0 through the frequency adjustment of the control end of the voltage-controlled oscillator, the phase locking state is realized, and accordingly the input mains supply 50Hz is adjusted to be 5KHz to be output.
Optionally, the frequency multiplication unit 105 is connected to the frequency-voltage conversion unit 104, and the mains supply output by the frequency multiplication unit 105 is input to the frequency-voltage conversion unit 104, so that the mains supply frequency is converted into a real-time voltage value, that is, an input mains supply frequency signal is converted into a voltage signal according to a linear relationship, and when the input frequency signal changes, the output voltage signal also responds to the change.
As shown in fig. 6, the sawtooth wave generating circuit further includes: a follower unit 106 and/or an amplifying unit 107.
When only the follower unit 106 is further included, the input terminal of the follower unit 106 inputs the first preset voltage or is connected to the output terminal of the frequency-voltage conversion unit 104, and the output terminal of the follower unit 106 is connected to the input terminal of the constant current source unit 102. The follower unit 106 is used to isolate the channel of the voltage of the frequency-to-voltage conversion unit from the channel of the voltage of the amplifying unit.
When only the amplifying unit 107 is further included, the input terminal of the amplifying unit 107 inputs the first preset voltage or is connected to the output terminal of the frequency-voltage converting unit 104, and the output terminal of the follower unit 106 is connected to the input terminal of the constant current source unit 102.
When the frequency-voltage conversion unit further comprises the following unit 106 and the amplifying unit 107, the input end of the following unit 106 inputs the first preset voltage or is connected with the output end of the frequency-voltage conversion unit 104, and the output end of the following unit 106 is connected with the input end of the amplifying unit 107; an output terminal of the amplifying unit 107 is connected to an input terminal of the constant current source unit 102.
The amplifying unit 107 is configured to amplify the input first preset voltage.
Alternatively, as shown in fig. 6, the following unit 106 may include: and an operational amplifier U2.
The non-inverting input end of the operational amplifier U2 is the input end of the following unit 106; the inverting input end of the operational amplifier U2 is connected with the output end of the operational amplifier U2, and the voltage of the input end of the operational amplifier U2 is the same as the voltage of the output end, so that the following function is realized. The output end of the operational amplifier U2 is the output end of the following unit. Optionally, the non-inverting input end of the operational amplifier U2 may be connected in series with a resistor, so as to prevent the current impact on the non-inverting input end of the operational amplifier U2 and damage the operational amplifier U2.
Alternatively, as shown in fig. 6, the amplifying unit 107 may include: an operational amplifier U3, a resistor R7 and a resistor R8;
one end of the resistor R7 is an input end of the amplifying unit 107, and the other end of the resistor R7 is connected to one end of the resistor R8 and an inverting input end of the operational amplifier U1 respectively;
the non-inverting input end of the operational amplifier U1 is grounded, and the output end of the operational amplifier U1 is connected with the other end of the R8 and serves as the output end of the amplifying unit. Alternatively, the resistor R8 may be replaced with two resistors connected in series so as to obtain a suitable resistance value.
For example, if the resistance of R7 in the amplifying unit 107 is 10K and the resistance of R8 is 15K, the output voltage U of the operational amplifier U2 out ＝1.5U 0 ，U 0 The voltage at the left end of the resistor R7 is thus amplified by the amplifying unit 107.
The sawtooth wave generating circuit amplifies the input mains frequency through the frequency multiplication unit, and then the output amplified mains frequency is input into the frequency-voltage conversion unit for conversion between frequency and voltage to obtain real-time voltage; and the amplifying unit amplifies the input real-time voltage and inputs the amplified real-time voltage into the constant current source unit. When the mains voltage input in the control switch unit is in the positive half axis of the corresponding sine wave, the diode D1 is turned off, the diode D2 is turned on, the triode Q1 is turned on, the output end of the control switch unit is connected with the input end of the constant current source unit, at the moment, the resistor R2 has smaller resistance value and is equivalent to a direct short circuit constant current source unit, namely the constant current source unit is turned off, and therefore the sawtooth wave generating unit discharges through the resistor R2. When the mains voltage is in the negative half axis of the corresponding sine wave, the diode D1 is turned on, the diode D2 is turned off, the triode Q1 is turned off, which is equivalent to the turning off of the control switch unit, namely, the constant current source unit connected with the control switch unit is disconnected from the ground, and then the stable current generated by the first preset voltage input constant current source unit is input into the sawtooth wave generating unit, so that the sawtooth wave generating unit charges. Thus, the sawtooth wave generating unit is continuously charged and discharged along with the period of the mains voltage, and the sawtooth wave is generated. After one period of the mains supply period is completed, the capacitor C4 generates a sawtooth wave, after the capacitor C4 enters the next period, the capacitor C4 is restarted to charge and discharge, the sawtooth wave is generated along with the period transformation of the mains supply voltage, and the generated sawtooth wave can update the slope and the amplitude of the sawtooth wave in real time along with the change of the mains supply frequency. I.e. when the mains frequency is large, the saw-tooth slope is large, the amplitude is also large, and when the mains frequency is reduced, the saw-tooth slope is small, and the amplitude is also small.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.
Claims (10)
1. A sawtooth wave generating circuit, comprising: a control switch unit, a constant current source unit and a sawtooth wave generating unit;
the input end of the control switch unit inputs the mains voltage, the output end of the control switch unit, the input end of the sawtooth wave generating unit and the input end of the constant current source unit are connected together, and the control switch unit is used for controlling the on and off of the constant current source unit according to the mains voltage;
the input end of the constant current source unit is also input with a first preset voltage, the output end of the constant current source unit is connected with the input end of the constant current source unit, and the constant current source unit is used for converting the input first preset voltage into stable current and inputting the stable current into the sawtooth wave generating unit;
the sawtooth wave generating unit is used for controlling the current output by the constant current source unit through the control switch unit to generate sawtooth waves which are synchronous with the mains voltage and can update the slope and the amplitude in real time along with the mains frequency.
2. The saw-tooth wave generating circuit according to claim 1, wherein the control switch unit includes a control subunit and a switch subunit;
the input end of the control subunit is the input end of the control switch unit, the output end of the control subunit is connected with the input end of the switch subunit, and the output end of the switch subunit is the output end of the control switch unit.
3. The saw-tooth wave generation circuit of claim 2, wherein the control subunit comprises: diode D1, diode D2, resistor R1, and capacitor C1;
one end of the resistor R1 is connected with a power supply of a second preset voltage, and the other end of the resistor R1 is respectively connected with the anode of the diode D1, the anode of the diode D2 and one end of the capacitor C1;
the mains voltage input by the cathode of the diode D1;
the negative electrode of the diode D2 is the output end of the control subunit;
the other end of the capacitor C1 is grounded.
4. The saw-tooth wave generating circuit of claim 2, wherein the switching subunit comprises: transistor Q1 and resistor R2;
the base electrode of the triode Q1 is connected with the output end of the control subunit, the collector electrode of the triode Q1 is connected with one end of the resistor R2, and the emitter electrode of the triode Q1 is grounded;
the other end of the resistor R2 is the output end of the switch subunit.
5. The saw-tooth wave generating circuit according to any one of claims 1 to 4, wherein the constant current source unit includes: the operational amplifier U1, the resistor R3, the resistor R4, the resistor R5, the damping capacitor C2 and the damping capacitor C3;
the non-inverting input end of the operational amplifier U1 is the input end of the constant current source unit;
the output end of the operational amplifier U1 is respectively connected with one end of the resistor R3, one end of the resistor R4, one end of the damping capacitor C2 and one end of the damping capacitor C3; the other end of the resistor R3 and the other end of the damping capacitor C2 are connected with the non-inverting input end of the operational amplifier U1; the other end of the resistor R4 and the other end of the damping capacitor C3 are respectively connected with the inverting input end of the operational amplifier U1 and one end of the resistor R5, and the other end of the resistor R5 is grounded.
6. The saw-tooth wave generation circuit according to any one of claims 1 to 4, wherein the saw-tooth wave generation unit includes a capacitor C4;
one end of the capacitor C4 is used as an input end of the sawtooth wave generating unit, the other end of the capacitor C4 is grounded, and the capacitor C4 is used for generating sawtooth waves which are synchronous with the mains voltage and can update the slope and the amplitude in real time along with the mains frequency.
7. The saw-tooth wave generating circuit as defined in claim 1, further comprising: a frequency-voltage conversion unit;
the input end of the frequency-voltage conversion unit inputs the mains frequency, and the output end of the frequency-voltage conversion unit is connected with the input end of the constant current source unit and is used for inputting the first preset voltage for the constant current source unit.
8. The saw-tooth wave generation circuit of claim 7, further comprising: a follower unit and/or an amplifier unit;
when only the following unit is further included, the input end of the following unit inputs the first preset voltage or is connected with the output end of the frequency voltage conversion unit, and the output end of the following unit is connected with the input end of the constant current source unit;
when the constant current source unit only comprises an amplifying unit, the input end of the amplifying unit inputs the first preset voltage or is connected with the output end of the frequency voltage conversion unit, and the output end of the following unit is connected with the input end of the constant current source unit;
when the frequency-voltage conversion unit is further arranged, the input end of the following unit inputs the first preset voltage or is connected with the output end of the frequency-voltage conversion unit, and the output end of the following unit is connected with the input end of the amplifying unit; the output end of the amplifying unit is connected with the input end of the constant current source unit.
9. The saw-tooth wave generating circuit according to claim 8, wherein the following unit includes: an operational amplifier U2;
the non-inverting input end of the operational amplifier U2 is the input end of the following unit; the inverting input end of the operational amplifier U2 is connected with the output end of the operational amplifier U2, and the output end of the operational amplifier U2 is the output end of the following unit;
the amplifying unit includes: an operational amplifier U3, a resistor R7 and a resistor R8;
one end of the resistor R7 is an input end of the amplifying unit, and the other end of the resistor R7 is respectively connected with one end of the resistor R8 and an inverted input end of the operational amplifier U1;
the non-inverting input end of the operational amplifier U1 is grounded, and the output end of the operational amplifier U1 is connected with the other end of the R8 and serves as the output end of the amplifying unit.
10. The saw-tooth wave generation circuit of claim 7, further comprising: a frequency multiplication unit;
the input end of the frequency multiplication unit inputs the mains frequency, and the output end of the frequency multiplication unit is connected with the input end of the frequency voltage conversion unit and is used for amplifying the mains period by a preset multiple through the phase-locked chip and the counter.
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| CN101584117A (en) * | 2007-01-17 | 2009-11-18 | 爱特梅尔公司 | Differential amplitude controlled sawtooth generator |
| CN201426083Y (en) * | 2009-05-27 | 2010-03-17 | 深圳桑达国际电子器件有限公司 | Sawtooth signal control circuit and switch power supply |
| CN202679329U (en) * | 2012-07-04 | 2013-01-16 | 成都国微电子有限公司 | Sawtooth wave generator |
| CN104600965A (en) * | 2015-02-02 | 2015-05-06 | 上海发电设备成套设计研究院 | Analog UPS (Uninterruptible Power Supply) output control circuit |
| CN108777571A (en) * | 2018-07-27 | 2018-11-09 | 无锡雷利电子控制技术有限公司 | A kind of signal generating circuit structure |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7948280B2 (en) * | 2006-10-20 | 2011-05-24 | Enpirion, Inc. | Controller including a sawtooth generator and method of operating the same |
| US7671642B2 (en) * | 2006-12-13 | 2010-03-02 | Atmel Corporation | Amplitude controlled sawtooth generator |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101584117A (en) * | 2007-01-17 | 2009-11-18 | 爱特梅尔公司 | Differential amplitude controlled sawtooth generator |
| CN201426083Y (en) * | 2009-05-27 | 2010-03-17 | 深圳桑达国际电子器件有限公司 | Sawtooth signal control circuit and switch power supply |
| CN202679329U (en) * | 2012-07-04 | 2013-01-16 | 成都国微电子有限公司 | Sawtooth wave generator |
| CN104600965A (en) * | 2015-02-02 | 2015-05-06 | 上海发电设备成套设计研究院 | Analog UPS (Uninterruptible Power Supply) output control circuit |
| CN108777571A (en) * | 2018-07-27 | 2018-11-09 | 无锡雷利电子控制技术有限公司 | A kind of signal generating circuit structure |
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