CN111464155A - Sawtooth wave generating circuit - Google Patents
Sawtooth wave generating circuit Download PDFInfo
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- CN111464155A CN111464155A CN202010206504.4A CN202010206504A CN111464155A CN 111464155 A CN111464155 A CN 111464155A CN 202010206504 A CN202010206504 A CN 202010206504A CN 111464155 A CN111464155 A CN 111464155A
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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 suitable for the technical field of circuit control, and provides a sawtooth wave generating circuit, which comprises: the input end of the control switch unit inputs mains supply 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 supply voltage; the input end of the constant current source unit also inputs 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 supply voltage and can update the slope in real time along with the mains supply frequency, so that the problem that the driving signal is unreliable due to the fact that the driving signal cannot be correspondingly adjusted in real time along with the change of the mains supply frequency by the corresponding driving signal generated by the sawtooth waves in the prior art 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 existing sawtooth wave generating circuit can be formed by the evolution of a triangular wave generating circuit, the triangular wave generating circuit can comprise a same-phase 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, the output voltage of the integrator is linearly increased, and therefore the output voltage of the integrator is a triangular wave. The rising and falling slopes of the output voltage of the integrator are different by changing the time constant of the forward and backward integrations of the integrator, so that a sawtooth voltage can be obtained.
However, the conventional sawtooth wave generating circuit cannot correspondingly adjust the slope and amplitude voltage of the sawtooth wave along with the periodic variation of the mains supply, so that a corresponding driving signal generated based on the sawtooth wave cannot correspondingly adjust the driving signal along with the variation of the mains supply frequency in real time, and the driving signal is unreliable.
Disclosure of Invention
In view of this, an embodiment of the present invention provides a sawtooth wave generating circuit to solve the problem in the prior art that the slope and amplitude voltage of a sawtooth wave cannot be adjusted correspondingly with the change of a mains frequency due to a sawtooth wave in a periodic manner, so that a corresponding driving signal generated based on the sawtooth wave cannot be adjusted correspondingly with the change of the mains 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: the control switch unit, the constant current source unit and the sawtooth wave generating unit;
the input end of the control switch unit is used for inputting mains supply voltage, the output end of the control switch unit, the input end of the sawtooth wave generation unit and the input end of the constant current source unit are connected together, and the control switch unit is used for controlling the conduction and the closing of the constant current source unit according to the mains supply voltage;
the input end of the constant current source unit is also used for inputting 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 a 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 a sawtooth wave which is synchronous with the mains supply voltage and can update the slope and the amplitude in real time along with the mains supply frequency.
In one embodiment, 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.
In one embodiment, the control subunit 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 with 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 is input to the cathode of the diode D1;
the cathode of the diode D2 is the output end of the control subunit;
the other end of the capacitor C1 is grounded.
In one embodiment, the switch subunit includes: a transistor Q1 and a 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 one embodiment, the constant current source unit includes: an operational amplifier U1, a resistor R3, a resistor R4, a resistor R5, a vibration eliminating capacitor C2 and a vibration eliminating 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 vibration eliminating capacitor C2 and one end of the vibration eliminating capacitor C3; the other end of the resistor R3 and the other end of the vibration eliminating capacitor C2 are connected with the non-inverting input end of an operational amplifier U1; the other end of the resistor R4 and the other end of the vibration-eliminating 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 comprises a capacitor C4;
one end of the capacitor C4 is used as the 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 a sawtooth wave which is synchronous with the mains supply voltage and can update the slope and the amplitude in real time along with the mains supply frequency.
In one embodiment, the method further comprises: a frequency-voltage conversion unit;
the input end of the frequency-voltage conversion unit inputs commercial power frequency, and the output end of the frequency-voltage conversion unit is connected with the input end of the constant current source unit and used for inputting the first preset voltage to the constant current source unit.
In one embodiment, the method further comprises: a following unit and/or an amplifying unit;
when only the following unit is 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 circuit 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 circuit further comprises the following unit and the amplifying unit, the first preset voltage is input to the input end of the following unit or the output end of the frequency-voltage conversion unit is connected, 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 one embodiment, the follower unit includes: a shipper 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 follower unit;
the amplification unit includes: the operational amplifier U3, the resistor R7 and the 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 one embodiment, the method further comprises: a frequency doubling unit;
the input end of the frequency doubling unit is used for inputting the commercial power frequency, and the output end of the frequency doubling unit is connected with the input end of the frequency-voltage conversion unit and used for realizing the periodic amplification of the commercial power by preset times through the phase-locked chip and the counter.
Compared with the prior art, the embodiment of the invention has the following beneficial effects: the input end of the control switch unit inputs mains voltage, and the conduction and the closing of the sawtooth wave generation unit and the constant current source unit are controlled through the mains voltage. When the mains voltage is in the positive half shaft of the corresponding sine wave, the control switch unit is switched on, namely the constant current source unit is cut off, so that the constant current source unit is closed, and the sawtooth wave generating unit discharges through the control switch unit. When mains voltage is in the sinusoidal wave's that corresponds negative semi-axis, the control switch unit is closed, and the stable current input sawtooth wave that first predetermine voltage input constant current source unit and produce the unit for sawtooth wave produces the unit and charges, and until mains voltage is in the sinusoidal wave's that corresponds positive semi-axis the end of charging when the control switch unit switches on, sawtooth wave produces the unit and discharges through the control switch unit, and along with mains voltage's cycle transformation and produce sawtooth wave, and this sawtooth wave that produces is synchronous with mains voltage and can be along with the change of the frequency of first predetermined voltage real-time update slope and amplitude.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
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 diagram of a frequency-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 particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the 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 explain the technical means of the present invention, the following description will be given by way of 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 mains voltage, the output end of the control switch unit 101, the input end of the sawtooth wave generation 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 further inputs a first preset voltage, the output end of the constant current source unit 102 is connected to the input end of the constant current source unit 102, and the constant current source unit 102 is configured to convert the input first preset voltage into a stable current and input the stable current to 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 the amplitude in real time along with the mains frequency.
According to the sawtooth wave generating circuit, mains voltage is input to the input end of the control switch unit, and the sawtooth wave generating unit and the constant current source unit are controlled to be switched on and off through the mains voltage. When the mains voltage is in the positive half shaft of the corresponding sine wave, the control switch unit is switched on, namely, the constant current source unit is short-circuited, so that the constant current source unit is closed, and the sawtooth wave generating unit discharges through the control switch unit. When mains voltage is in the sinusoidal wave's that corresponds negative semi-axis, the control switch unit is closed, and the stable current input sawtooth wave that first predetermine voltage input constant current source unit and produce the unit for sawtooth wave produces the unit and charges, and until mains voltage is in the sinusoidal wave's that corresponds positive semi-axis the end of charging when the control switch unit switches on, sawtooth wave produces the unit and discharges through the control switch unit, and along with mains voltage's cycle transformation and produce sawtooth wave, and this sawtooth wave that produces is synchronous with mains voltage and can be along with the change of the frequency of first predetermined voltage real-time update slope and amplitude.
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, i.e. 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 with 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 supply of the second preset voltage may be a power supply of a voltage of 15V.
The mains voltage is input to the cathode of the diode D1;
the cathode of the diode D2 is the output end of the control subunit;
the other end of the capacitor C1 is grounded.
Optionally, a resistor may be connected in series between one end of the resistor R1 and the first preset voltage input port in the control subunit 1011, or another resistor may be connected in series between the connection point of the anode of the diode D1 and the anode of the diode D2 and the resistor R1, so as to achieve the voltage drop target.
Optionally, as shown in fig. 2, the switch subunit 1012 includes: a transistor Q1 and a 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 1012.
In fig. 2, when the mains voltage is at the positive half-axis of the corresponding sine wave, the diode D1 is not turned on, and the diode D2 is turned on by the power of the second predetermined voltage, so that the transistor Q1 is turned on. Optionally, 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, and at this time, because the resistance value of the resistor R2 is smaller, the constant current source unit is equivalent to a direct short circuit, namely the constant current source unit is turned off, the sawtooth wave generating unit discharges through the resistor R2.
When the mains voltage is in the negative half shaft 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 controlling the switch unit to be turned off, and then the stable current generated by the first preset voltage input constant current source unit is input to the sawtooth wave generating unit, so that the sawtooth wave generating unit is charged. Therefore, the sawtooth wave generating unit is charged and discharged continuously 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: an operational amplifier U1, a resistor R3, a resistor R4, a resistor R5, a vibration-eliminating capacitor C2 and a vibration-eliminating capacitor C3.
The non-inverting input end of the operational amplifier U1 is the input end of the constant current source unit, i.e., 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 vibration eliminating capacitor C2 and one end of the vibration eliminating capacitor C3; the other end of the resistor R3 and the other end of the vibration eliminating capacitor C2 are connected with the non-inverting input end of an operational amplifier U1; the other end of the resistor R4 and the other end of the vibration-eliminating 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 non-inverting input terminal of the operational amplifier U1 has voltage, the current output from the output terminal returns to the non-inverting input terminal through the parallel circuit formed by the resistor R3 and the capacitor C2, and a constant current is formed.
Optionally, the constant current source unit may further include a resistor R6, one end of the resistor R6 is connected to the input terminal of the control switch unit, and the other end is connected to the input terminal of the constant current source unit, and the resistor R6 is used for limiting the current entering the constant current source unit.
Optionally, as shown in fig. 3, the sawtooth wave generating unit 103 includes a capacitor C4.
The one end of electric capacity C4 is regarded as the input of sawtooth wave generation unit is connected respectively the output of control switch unit with the input of constant current source unit, electric capacity C4's other end ground connection, be used for on the electric capacity C4 to produce with mains voltage synchronous and can follow the sawtooth wave of mains frequency real-time update slope and amplitude.
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 commercial power 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, and is configured 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 inverting input end (namely THRS end) of the comparator of the frequency-voltage conversion chip is connected with the input mains frequency. Optionally, one end of a capacitor C5 may be connected between the commercial frequency input interface and the inverting input terminal (i.e., the THRS terminal) of the comparator of the frequency-voltage conversion chip, the other end of the capacitor C5 is connected to the resistor R9, the anode of the diode D3, and the cathode of the diode D4, the other end of the resistor R9 and the cathode of the diode D3 are connected to the voltage of 15V, and the anode 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 optionally, the preset power supply is a 15V power supply. Optionally, two ends of the capacitor C6 may be connected in parallel with two capacitors, and a resistor may be connected in series between the resistor R10 and the preset power supply.
The non-inverting input end (i.e. the Com _ IN end) of the comparator of the frequency-voltage conversion chip is respectively connected with one end of the resistor R11 and one end of the 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 a capacitor C7 may be connected between the resistor R11 and the preset power supply, and the other end of the capacitor C7 is grounded. Optionally, the preset power supply is a 15V power supply.
The positive power supply terminal (i.e., VCC terminal) of the frequency-voltage conversion chip is connected between the resistor R11 and a predetermined power supply.
The frequency output end (i.e., the FRE _ OUT end) of the frequency-voltage conversion chip is connected with the negative power end (i.e., the GND end) of the frequency-voltage conversion chip and then grounded, the current output end (i.e., the 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 a 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 an operational amplifier U4, the non-inverting input end of the operational amplifier U4 is grounded, and one end of a capacitor. The operational amplifier U4, the resistor R13 and the resistor R14 constitute a constant current source circuit. Optionally, two ends of the capacitor C9 may be connected in parallel with a plurality of capacitors, so as to achieve a constant effect on the current output by the current output terminal of the frequency-voltage conversion chip.
In fig. 4, the commercial power frequency signal is input to the inverting input terminal of the comparator of the frequency-voltage conversion chip. When the falling edge of the mains supply frequency signal comes, the voltage is compared with the potential of the non-inverting input end of the comparator to output high level, the internal trigger of the frequency-voltage conversion chip is set, the constant current source (namely the circuit formed by the amplifier U4, the surrounding resistor and the capacitor) in the internal trigger charges the capacitor C8, and meanwhile, the power supply VCC charges the capacitor C7 through R11. When the voltage of the capacitor C8 is larger than 2VCC/3, the trigger in the frequency-voltage conversion chip is reset, the C8 discharges through R15, and the timing capacitor C7 discharges rapidly at the same time, thereby completing a charging and discharging process. After that, the circuit formed by the frequency-voltage conversion chip and the operational amplifier repeats the above working process every time through a charging and discharging process, so that the frequency/voltage conversion is realized.
Optionally, in order to improve the conversion accuracy of the frequency-voltage conversion chip, the commercial power frequency may be amplified by a frequency doubling unit, that is, the sawtooth wave generation circuit further includes a frequency doubling unit 105, the commercial power frequency is input to an input end of the frequency doubling unit 105, and an output end of the frequency doubling unit 105 is connected to an input end of the frequency-voltage conversion unit 104, and is configured to realize periodic amplification of the commercial power by a preset multiple through a phase-locked chip and a counter. For example, in this embodiment, the phase-locked chip and the counter may amplify the commercial power frequency by 100 times, and then convert the input commercial power frequency into a corresponding real-time voltage through the frequency-voltage conversion unit.
Optionally, as shown in fig. 5, the frequency doubling unit 105 may include: the phase-locked loop comprises a phase-locked chip, a shift counter and a connecting circuit between the phase-locked chip and the shift counter.
And a signal input end of the phase-locked chip inputs a mains supply frequency signal. For filtering, a capacitor may be connected, the other end of the capacitor being connected to ground.
The comparison signal input end of the phase-locked chip is connected with the output end Q4B of the shift counter after being connected with a resistor R14 in series. The output end of the voltage-controlled oscillator of the phase-locked chip is connected to the clock input end of the shift counter, 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 further connected to one end of a parallel circuit formed by a resistor R15 and a capacitor C10, and the other end of the parallel circuit is grounded. And a parallel capacitor is connected between the two external oscillation capacitor ends of the phase-locked chip. The power supply negative terminal of the phase-locked chip is grounded, the power supply positive terminal of the phase-locked chip is connected with a power supply with preset voltage, and the selectable power supply with preset voltage can be a power supply with 15V voltage. The control end of a 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 end of a capacitor C12 and one end of 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 a phase comparator of the phase-locked chip after being connected with a resistor R18 in series, one end of a capacitor C14 is further connected between the resistor R18 and the resistor R17, and the other end of the capacitor C.
The output end Q4A of the shift counter is connected to the count permission control end of the shift counter and one end of the 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 supply with the preset voltage may be a power supply with a voltage of 15V.
Optionally, the frequency multiplication unit 105 compares the levels of the signals input by the signal input end and the comparison signal input end of the phase-locked chip, and when the frequency of the signal input by the signal input end is lower than the frequency of the comparison signal input by the comparison signal input end, the output end of the phase comparator ii of the phase-locked chip outputs logic "0", otherwise, the output end of the phase comparator ii of the phase-locked chip outputs logic "1". The output end of the voltage-controlled oscillator of the phase-locked chip is related to the level states of signals of two input ends of signals input by the signal input end and 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 level output by the output end of the voltage-controlled oscillator is fed back to the shift counter, 100-time 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 frequency is multiplied by 100 times when the level is fed back to the input end of the phase-locked chip, the phase difference of 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 therefore the input commercial power 50Hz is adjusted to be 5KHz output.
Optionally, the frequency doubling unit 105 is connected to the frequency-voltage conversion unit 104, and the commercial power output by the frequency doubling unit 105 is input into the frequency-voltage conversion unit 104, so that the commercial power frequency is converted into a real-time voltage value, that is, the input commercial power 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 changes in response.
As shown in fig. 6, the sawtooth wave generating circuit further includes: a following unit 106 and/or an amplifying unit 107.
When only the following unit 106 is further included, the input terminal of the following unit 106 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 following 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-voltage conversion unit and the channel of the voltage of the amplification 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 following unit 106 is connected to the input terminal of the constant current source unit 102.
When the following unit 106 and the amplifying unit 107 are further included, the first preset voltage is input to the input terminal of the following unit 106 or the output terminal of the frequency-voltage converting unit 104 is connected, and the output terminal of the following unit 106 is connected to the input terminal of the amplifying unit 107; the output end of the amplifying unit 107 is connected to the input end of the constant current source unit 102.
The amplifying unit 107 is configured to amplify the input first preset voltage.
Optionally, as shown in fig. 6, the circuit diagram of generating a sawtooth wave, wherein the following unit 106 may include: and a shipper 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 that 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, a resistor may be connected in series to the non-inverting input terminal of the operational amplifier U2, so as to prevent current surge to the non-inverting input terminal of the operational amplifier U2 from damaging the operational amplifier U2.
Alternatively, as shown in fig. 6, the amplifying unit 107 may include: the operational amplifier U3, the resistor R7 and the 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 respectively connected to 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. Alternatively, the resistor R8 may be replaced by two resistors in series 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 terminal voltage U of the operational amplifier U2 is obtainedout＝1.5U0，U0Is the voltage at the left end of the resistor R7, the amplifying unit 107 can amplify the voltage.
The sawtooth wave generating circuit amplifies the input commercial power frequency through the frequency doubling unit, then inputs the output amplified commercial power frequency into the frequency-voltage conversion unit, and converts the frequency and the 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 into the control switch unit is at the positive half shaft of the corresponding sine wave, the diode D1 is cut off, the diode D2 is switched on, the triode Q1 is switched on, and the output end of the control switch unit is connected with the input end of the constant current source unit, at this time, because the resistance value of the resistor R2 is small, the constant current source unit is equivalent to a direct short circuit, namely the constant current source unit is switched off, the sawtooth wave generating unit discharges through the resistor R2. When the mains voltage is in the negative half shaft 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 that the control switch unit is turned off, that is, the constant current source unit connected with the control switch unit is disconnected from the ground, and then the stabilized 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 is charged. Therefore, the sawtooth wave generating unit is charged and discharged continuously along with the period of the mains voltage, and therefore sawtooth waves are generated. After one period of the mains supply is finished, the capacitor C4 generates a sawtooth wave, after the next period, the charging and discharging of the capacitor C4 are restarted, the sawtooth wave is generated along with the period change 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. Namely, when the mains frequency is high, the slope and the amplitude of the sawtooth wave are high, and when the mains frequency is reduced, the slope and the amplitude of the sawtooth wave are low.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present 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 solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. A sawtooth wave generation circuit, comprising: the control switch unit, the constant current source unit and the sawtooth wave generating unit;
the input end of the control switch unit is used for inputting mains supply voltage, the output end of the control switch unit, the input end of the sawtooth wave generation unit and the input end of the constant current source unit are connected together, and the control switch unit is used for controlling the conduction and the closing of the constant current source unit according to the mains supply voltage;
the input end of the constant current source unit is also used for inputting 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 a 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 a sawtooth wave which is synchronous with the mains supply voltage and can update the slope and the amplitude in real time along with the mains supply frequency.
2. The sawtooth wave generation circuit of claim 1 wherein 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.
3. The sawtooth generation circuit of claim 2 wherein the control subunit comprises: 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 with 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 is input to the cathode of the diode D1;
the cathode of the diode D2 is the output end of the control subunit;
the other end of the capacitor C1 is grounded.
4. The sawtooth generation circuit of claim 2 wherein the switch subunit comprises: a transistor Q1 and a 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 sawtooth wave generation circuit of any one of claims 1 to 4 wherein the constant current source unit comprises: an operational amplifier U1, a resistor R3, a resistor R4, a resistor R5, a vibration eliminating capacitor C2 and a vibration eliminating 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 vibration eliminating capacitor C2 and one end of the vibration eliminating capacitor C3; the other end of the resistor R3 and the other end of the vibration eliminating capacitor C2 are connected with the non-inverting input end of an operational amplifier U1; the other end of the resistor R4 and the other end of the vibration-eliminating 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 sawtooth wave generation circuit of any one of claims 1 to 4 wherein the sawtooth wave generation unit comprises a capacitor C4;
one end of the capacitor C4 is used as the 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 a sawtooth wave which is synchronous with the mains supply voltage and can update the slope and the amplitude in real time along with the mains supply frequency.
7. The sawtooth generation circuit of claim 1 further comprising: a frequency-voltage conversion unit;
the input end of the frequency-voltage conversion unit inputs commercial power frequency, and the output end of the frequency-voltage conversion unit is connected with the input end of the constant current source unit and used for inputting the first preset voltage to the constant current source unit.
8. The sawtooth generation circuit of claim 7 further comprising: a following unit and/or an amplifying unit;
when only the following unit is 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 circuit 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 circuit further comprises the following unit and the amplifying unit, the first preset voltage is input to the input end of the following unit or the output end of the frequency-voltage conversion unit is connected, 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 sawtooth generation circuit of claim 8 wherein the follower unit comprises: a shipper 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 follower unit;
the amplification unit includes: the operational amplifier U3, the resistor R7 and the 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 sawtooth generation circuit of claim 7 further comprising: a frequency doubling unit;
the input end of the frequency doubling unit is used for inputting the commercial power frequency, and the output end of the frequency doubling unit is connected with the input end of the frequency-voltage conversion unit and used for realizing the periodic amplification of the commercial power by preset times through the phase-locked chip and the counter.
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| US20080094114A1 (en) * | 2006-10-20 | 2008-04-24 | Mirmira Ramarao Dwarakanath | Controller including a sawtooth generator and method of operating the same |
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| CN101584117A (en) * | 2007-01-17 | 2009-11-18 | 爱特梅尔公司 | Differential amplitude controlled sawtooth generator |
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| 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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| US20080094114A1 (en) * | 2006-10-20 | 2008-04-24 | Mirmira Ramarao Dwarakanath | Controller including a sawtooth generator and method of operating the same |
| US20080143394A1 (en) * | 2006-12-13 | 2008-06-19 | Atmel Corporation | Amplitude controlled sawtooth generator |
| 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 |
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