CN215072203U - Soft start circuit and motor - Google Patents
Soft start circuit and motor Download PDFInfo
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- CN215072203U CN215072203U CN202120561174.0U CN202120561174U CN215072203U CN 215072203 U CN215072203 U CN 215072203U CN 202120561174 U CN202120561174 U CN 202120561174U CN 215072203 U CN215072203 U CN 215072203U
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Abstract
The utility model relates to a motor control technology field discloses a soft start circuit and motor. The soft start circuit comprises a sawtooth wave generating circuit, a reference voltage generating circuit and a power regulating circuit, wherein the sawtooth wave generating circuit can generate sawtooth wave voltage according to a first auxiliary voltage when the motor is started, the reference voltage generating circuit can generate variable reference voltage according to a second auxiliary voltage when the motor is started, the power regulating circuit is respectively connected with the sawtooth wave generating circuit and the reference voltage generating circuit, the starting power of the motor can be regulated according to the sawtooth wave voltage and the reference voltage so as to limit the starting power of the motor, and the starting power of the motor is gradually reduced until the starting power approaches the rated power of the motor. When the motor is started, the sawtooth wave voltage and the reference voltage are generated only according to the auxiliary voltage, and then the starting power of the motor is adjusted according to the sawtooth wave voltage and the reference voltage, so that the soft start of the motor can be conveniently realized.
Description
Technical Field
The utility model relates to a motor control technical field especially relates to a soft start circuit and motor.
Background
The hard starting of the motor means that the motor is directly applied with full voltage for starting, the starting current of the motor during the hard starting is generally 3 to 7 times of rated current, even 20 to 30 times, and the situation of exceeding the rated current is probably acceptable for a low-power motor, but is extremely unfavorable for a high-power motor, and particularly when the high-power motor is frequently and hard started, the motor not only can cause serious interference to a power grid, but also can cause serious heating of the motor, and the motor can be burnt seriously, so the hard starting can be generally only applied to the low-power motor.
The soft start of the motor corresponds to the hard start, and generally means that at the moment of starting the motor, the motor is controlled to be slowly started at a lower current within a certain time, and then the motor is controlled to work at a rated current after the time. The starting current is generally small in the soft starting process of the motor, the influence on the motor is small, and the soft starting process is generally not limited by the manufacturing process or the structure of the motor, so that the soft starting of the motor has certain advantages relative to the hard starting.
At present, a plurality of soft start schemes are designed for the motor, but the technical problems that the soft start of the motor cannot be conveniently realized or the effect is not good in the soft start process of the motor are generally existed.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a soft start circuit and motor can conveniently realize the soft start of motor.
The embodiment of the utility model provides a following technical scheme:
in a first aspect, an embodiment of the present invention provides a soft start circuit, including:
the sawtooth wave generating circuit is used for being applied with a first auxiliary voltage and generating sawtooth wave voltage according to the first auxiliary voltage;
a reference voltage generating circuit to which a second auxiliary voltage is applied and which generates a reference voltage according to the second auxiliary voltage;
and the power regulating circuit is respectively connected with the sawtooth wave circuit, the reference voltage generating circuit and the motor and is used for regulating the starting power of the motor according to the sawtooth wave voltage and the reference voltage so as to limit the starting power of the motor and realize the soft start of the motor.
Optionally, the power regulating circuit comprises a comparing circuit and a switching circuit;
the comparison circuit comprises a first input end, a second input end and an output end, the first input end of the comparison circuit is connected with the sawtooth wave generation circuit, the second input end of the comparison circuit is connected with the reference voltage generation circuit, and the comparison circuit obtains a pulse voltage with the duty ratio gradually increased from 0 or gradually decreased from 1 according to the sawtooth wave voltage and the reference voltage and outputs the pulse voltage through the output end of the comparison circuit;
and the switching circuit is respectively connected with the motor, the output end of the comparison circuit and a motor power supply, and adjusts the starting power of the motor according to the pulse voltage and the power supply voltage output by the motor power supply.
Optionally, the switch circuit includes an NMOS transistor and a first diode;
the negative pole of the first diode, the first end of the motor and the power supply of the motor are connected together, the positive pole of the first diode, the second end of the motor and the drain electrode of the NMOS tube are connected, the grid electrode of the NMOS tube is connected with the output end of the comparison circuit, and the source electrode of the NMOS tube is grounded.
Optionally, the sawtooth wave generating circuit includes a first operational amplifier, a second diode, a first capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor;
one end of the first resistor is used for being applied with the first auxiliary voltage, the other end of the first resistor, one end of the second resistor, one end of the third resistor and the non-inverting input end of the first operational amplifier are connected together, the other end of the second resistor is grounded, the other end of the third resistor, the cathode of the second diode and the output end of the first operational amplifier are connected, the anode of the second diode, one end of the fourth resistor and one end of the fifth resistor are connected, the other end of the fourth resistor, one end of the first capacitor, the inverting input end of the first operational amplifier and the first input end of the comparison circuit are connected, the other end of the first capacitor is grounded, and the other end of the fifth resistor is used for being applied with the first auxiliary voltage.
Optionally, the reference voltage generating circuit includes a sixth resistor, a seventh resistor, and a second capacitor;
one end of the sixth resistor is used for being applied with the second auxiliary voltage, the other end of the sixth resistor, one end of the seventh resistor, one end of the second capacitor and the second input end of the comparison circuit are connected, and the other end of the seventh resistor and the other end of the second capacitor are grounded.
Optionally, the device further comprises a voltage stabilizing circuit;
the first end of the voltage stabilizing circuit, the grid electrode of the NMOS tube and the output end of the comparison circuit are connected together, the second end of the voltage stabilizing circuit is grounded, and the voltage stabilizing circuit is used for realizing overvoltage protection between the grid electrode and the source electrode of the NMOS tube.
Optionally, a current limiting circuit is further included;
one end of the current limiting circuit, the first end of the voltage stabilizing circuit and the output end of the comparison circuit are connected together, the other end of the current limiting circuit is connected with the grid electrode of the NMOS tube, and the current limiting circuit is used for limiting the current flowing through the NMOS tube.
Optionally, a discharge circuit is further included;
one end of the discharge circuit, one end of the current limiting circuit and the grid electrode of the NMOS tube are connected together, the other end of the discharge circuit is grounded, and the discharge circuit is used for discharging junction capacitance of the NMOS tube.
Optionally, the comparison circuit comprises a second operational amplifier;
the inverting input end of the second operational amplifier is the first input end of the comparison circuit, the non-inverting input end of the second operational amplifier is the second input end of the comparison circuit, and the output end of the second operational amplifier is the output end of the comparison circuit.
In a second aspect, the present invention provides an electric machine comprising a soft start circuit as described above.
The embodiment of the utility model provides a beneficial effect is: a soft start circuit and a motor are provided. The soft start circuit comprises a sawtooth wave generating circuit, a reference voltage generating circuit and a power regulating circuit, wherein the sawtooth wave generating circuit can generate sawtooth wave voltage according to a first auxiliary voltage when the motor is started, the reference voltage generating circuit can generate reference voltage according to a second auxiliary voltage when the motor is started, the power regulating circuit is respectively connected with the sawtooth wave generating circuit and the reference voltage generating circuit, the starting power of the motor can be regulated according to the sawtooth wave voltage and the reference voltage so as to limit the starting power of the motor, and the starting power of the motor is gradually reduced until approaching the rated power of the motor, so that the soft start of the motor is realized. When the motor is started, the sawtooth wave voltage and the variable reference voltage are generated only according to the auxiliary voltage, and then the starting power of the motor is adjusted according to the sawtooth wave voltage and the reference voltage, so that the soft start of the motor can be conveniently realized.
Drawings
The embodiments are illustrated by way of example only in the accompanying drawings, in which like reference numerals refer to similar elements and which are not to be construed as limiting the embodiments, and in which the figures are not to scale unless otherwise specified.
Fig. 1 is a schematic structural diagram of a soft start circuit according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a soft start circuit of a motor;
FIG. 3 is a schematic diagram of a power conditioning circuit provided in FIG. 1;
fig. 4 is a schematic circuit diagram of a soft start circuit according to an embodiment of the present invention;
fig. 5 to 7 are waveforms of pulse voltages output by the comparison circuit provided in fig. 4 during the soft start of the motor.
Detailed Description
To facilitate an understanding of the present application, the present application is described in more detail below with reference to the accompanying drawings and detailed description. It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may be present. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, fig. 1 is a schematic diagram of a soft start circuit according to the present invention. As shown in fig. 1, the soft start circuit 100 includes a sawtooth wave generating circuit 10, a reference voltage generating circuit 20 and a power regulating circuit 30.
The sawtooth wave generating circuit 10 is applied with a first auxiliary voltage VCC1, the first auxiliary voltage VCC1 being generated after the system is powered on, so that the sawtooth wave generating circuit 10 generates a sawtooth wave voltage according to the first auxiliary voltage VCC1 when the motor is started, as can be understood, the sawtooth wave voltage is generated when the system is powered on.
The reference voltage generating circuit 20 is applied with a second auxiliary voltage VCC2, and the second auxiliary voltage VCC2 is also generated after the system is powered on, so that the reference voltage generating circuit 20 generates a reference voltage according to the second auxiliary voltage VCC2 when the motor is started, and it can be understood that the reference voltage is also generated when the system is powered on. The voltage of the reference voltage is variable, for example, the voltage of the reference voltage is gradually increased from zero.
The first auxiliary voltage VCC1 and the second auxiliary voltage VCC2 may be the same or different, that is, the first auxiliary voltage VCC1 and the second auxiliary voltage VCC2 may be from the same auxiliary power source established after the system is powered on, or from different auxiliary power sources.
The power regulating circuit 30 is respectively connected with the sawtooth wave generating circuit 10, the reference voltage generating circuit 20 and the motor, and the power regulating circuit 30 can regulate the starting power of the motor according to the sawtooth wave voltage generated by the sawtooth wave generating circuit 10 and the reference voltage generated by the reference voltage generating circuit 20, so that the soft start of the motor is realized.
In the process of soft starting of the motor, the power regulating circuit 30 applies the full voltage to the motor slowly according to the sawtooth wave voltage and the reference voltage, and compared with the hard starting (applying the full voltage to the motor directly), the starting power is low, after a period of time, the power regulating circuit 30 can apply the full voltage to the motor according to the sawtooth wave voltage and the reference voltage, the starting power of the motor approaches the rated power, at this time, the motor finishes the soft starting process, enters the normal working state, and the motor works at the rated power. Therefore, the impact of the excessive current generated in the moment of starting the motor on the power supply system can be avoided, and the normal work of the system is ensured, for example, in the situation that the motor is powered by using the switching power supply, the large current generated when the motor is started hard will cause the switching power supply to execute the protection action and stop outputting, and the motor cannot work.
In addition, the present embodiment can start the soft start of the motor when the motor needs to be started, that is, when the system is powered on, so that the soft start of the motor can be conveniently realized.
Although there are many soft start schemes designed for motors at present, the problems of narrow application range, inconvenient application or low reliability, low stability and the like often exist. For example, in patent publication No. CN207368911U, entitled motor soft start circuit, as shown in fig. 2, the scheme of the patent is to change the voltage across the capacitor C by inputting a PWM signal with a certain frequency to the terminal K during the soft start process, so as to ensure that the transistor T2 operates in a linear amplification region, thereby limiting the start current of the motor. Although the solution shown in fig. 2 allows a soft start of the motor, there are some drawbacks: because need make the motor get into the soft start process after filling with electric capacity C fully, mean that the motor must carry out once hard start when soft start, can' T be suitable for various application occasions well, application scope has certain limitation, simultaneously, triode T2 is in the enlarged state at soft start in-process, this operating condition can lead to triode T2 to generate heat, especially when frequent soft start, triode T2 has the risk of overheated burnout, the soft start function also can become invalid.
In view of this, the embodiment of the present invention provides a soft start circuit (see the following embodiments of the present invention specifically), which not only can widen the application range, but also can improve the reliability and stability of the soft start process of the motor.
As shown in fig. 3, the power conditioning circuit 30 includes a comparison circuit 31 and a switch circuit 32.
The comparison circuit 31 includes a first input terminal 31A, a second input terminal 31B and an output terminal 31C, the first input terminal 31A of the comparison circuit 31 is connected to the sawtooth wave generation circuit 10, the second input terminal 31B of the comparison circuit 31 is connected to the reference voltage generation circuit 20, and the comparison circuit 31 obtains a pulse voltage whose duty ratio is gradually increased from 0 or gradually decreased from 1 (hereinafter referred to as "pulse voltage with duty ratio change") according to the sawtooth wave voltage and the reference voltage and outputs the pulse voltage through the output terminal 31C of the comparison circuit 31.
The switch circuit 32 is connected to the motor M, the output terminal 31C of the comparison circuit 31, and the motor power supply, which is established when the system is powered on and is used to provide the power supply voltage for the motor M, and the switch circuit 32 adjusts the starting power of the motor M according to the pulse voltage with the changed duty ratio and the power supply voltage output by the power supply.
Specifically, as shown in fig. 4, the switch circuit 32 includes an NMOS (N-channel metal oxide semiconductor) transistor Q1 and a first diode D1.
The cathode of the first diode D1, the first end of the motor M and the power supply of the motor are connected together, the anode of the first diode D1, the second end of the motor M and the drain of the NMOS tube Q1 are connected together, the gate of the NMOS tube Q1 is connected with the output end of the comparison circuit 31, and the source of the NMOS tube Q1 is grounded.
When the first end of the motor M is applied with the supply voltage VCC3 outputted by the motor power supply and the NMOS transistor Q1 is turned on, the second end of the motor M is grounded through the NMOS transistor Q1, so that the current flows through the motor M, and when the NMOS transistor Q1 is turned off, the second end of the motor M cannot be grounded through the NMOS transistor Q1, so that no current flows through the motor. Therefore, the grid of the NMOS tube Q1 is driven and controlled by a pulse voltage with a variable duty ratio, the starting current of the motor M can be adjusted, and the soft start of the motor M is realized. In addition, when the gate of the NMOS transistor Q1 is driven and controlled by the pulse voltage with a varying duty ratio, since the NMOS transistor Q1 is switched between the on state and the off state, compared with the state where the transistor T2 shown in fig. 2 is in the amplification state, the NMOS transistor Q1 does not generate heat in this state, and the NMOS transistor Q1 does not need to be additionally cooled, which is suitable for the occasion of frequent starting of the motor, and can improve the reliability and stability of the motor in the soft starting process.
The pulse voltage whose duty ratio varies is generated by the comparison circuit 31 based on the comparison result of the sawtooth wave voltage generated by the sawtooth wave generation circuit 10 and the reference voltage generated by the reference voltage generation circuit 20.
As for the comparison circuit 31, more specifically, as shown in fig. 4, the comparison circuit 31 includes a second operational amplifier a 2.
The inverting input terminal of the second operational amplifier a2 is connected to the sawtooth wave generating circuit 10, the non-inverting input terminal of the second operational amplifier a2 is connected to the reference voltage generating circuit 20, and the output terminal of the second operational amplifier a2 is connected to the switching circuit 32 (the gate of the NMOS transistor Q1).
It is understood that the inverted input terminal of the second operational amplifier a2 is inputted with a sawtooth voltage, the non-inverted input terminal of the second operational amplifier a2 is inputted with a reference voltage, and the voltage of the reference voltage is variable, so that the output terminal of the second operational amplifier a2 can output a pulse voltage with a variable duty ratio, which is applied to the gate of the NMOS transistor Q1 to adjust the starting power of the motor M to realize the soft start of the motor M.
As shown in fig. 4, the sawtooth wave generating circuit 10 can generate a sawtooth wave voltage according to the first auxiliary voltage VCC1, and specifically, the sawtooth wave generating circuit 10 includes a first operational amplifier a1, a second diode D2, a first capacitor C1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5.
One end of the first resistor R1 may be applied with a first auxiliary voltage VCC1, the other end of the first resistor R1, one end of the second resistor R2, one end of the third resistor R3, and the non-inverting input terminal of the first operational amplifier a1 are commonly connected, the other end of the second resistor R2 is grounded, the other end of the third resistor R3, the cathode of the second diode D2, and the output terminal of the first operational amplifier a1 are connected, the anode of the second diode D2, one end of the fourth resistor R4, and one end of the fifth resistor R5 are connected, the other end of the fourth resistor R4, one end of the first capacitor C1, the inverting input terminal of the first operational amplifier a1, and the first input terminal of the comparison circuit 31 (the inverting input terminal of the second operational amplifier) are connected, the other end of the first capacitor C1 is grounded, and the other end of the fifth resistor R5 may be applied with a first auxiliary voltage VCC 1.
Positive feedback is introduced into the first operational amplifier A1 through the third resistor R3, the third resistor R3 and the first operational amplifier A1 form a hysteresis comparator, the hysteresis comparator has two threshold voltages, and when input is changed in a single direction, the output jumps once. When the input is changed from big to small, the corresponding threshold voltage is small; when the input is changed from small to large, the corresponding threshold voltage is large. Between these two threshold voltages, the output remains the original output.
The first operational amplifier a1 is a rail-to-rail operational amplifier, when the voltage at the non-inverting input terminal of the first operational amplifier a1 is greater than the voltage at the inverting input terminal, the first operational amplifier a1 outputs a high level (first auxiliary voltage VCC1), when the voltage at the non-inverting input terminal of the first operational amplifier a1 is less than the voltage at the inverting input terminal, the first operational amplifier a1 outputs a low level (zero voltage), when the first operational amplifier a1 outputs a high level, the voltage at the non-inverting input terminal of the first operational amplifier a1 is a threshold voltage Ua, when the first operational amplifier a1 outputs a high level, the voltage at the non-inverting input terminal of the first operational amplifier a1 is a threshold voltage Ub, and thus the voltage at the non-inverting input terminal of the first operational amplifier a1 will switch between the threshold voltage Ua and the threshold voltage Ub.
When the first operational amplifier a1 outputs a high level, according to the circuit structure, the voltage (threshold voltage Ua) at the non-inverting input terminal of the first operational amplifier a1 is equivalent to the product of the value obtained by connecting the first resistor R1 in parallel with the third resistor R3 and then connecting the second resistor R2 in series with the first auxiliary voltage VCC 1; when the first operational amplifier a1 outputs a low level, according to the circuit structure, the voltage (threshold voltage Ub) at the non-inverting input terminal of the first operational amplifier a1 is equivalent to the product of the value of the second resistor R2 connected in parallel with the third resistor R3 and then connected in series with the first resistor R1 and the first auxiliary voltage VCC 1. The threshold voltage Ua and the threshold voltage Ub correspond to the upper threshold voltage and the lower threshold voltage of the hysteresis comparator, respectively.
When the first operational amplifier a1 outputs a high level, the first auxiliary voltage VCC1 sequentially passes through the fifth resistor R5 and the fourth resistor R4 to charge the first capacitor C1, the second diode D2 plays an isolating role to prevent the output end voltage of the first operational amplifier a1 from charging the first capacitor C1 through the fourth resistor R4, so as to maintain the output end voltage of the first operational amplifier a1, the voltage of the first capacitor C1 gradually rises during the charging of the first capacitor C1, and when the voltage rises to a voltage greater than the non-inverting input end voltage (threshold voltage Ua) of the first operational amplifier a1, the first operational amplifier a1 outputs a low level.
When the first operational amplifier a1 outputs a low level, the electric energy stored in the first capacitor C1 is discharged through the fourth resistor R4 and the second diode D2, and the voltage of the first capacitor C1 is gradually reduced during the discharge of the first capacitor C1, and when the voltage is reduced to be less than the voltage (threshold voltage Ub) at the non-inverting input terminal of the first operational amplifier a1, the first operational amplifier a1 outputs a high level.
Accordingly, the first capacitor C1 is continuously charged and discharged, and the voltage of the first capacitor C1 varies between the threshold voltage Ua and the threshold voltage Ub, thereby generating a sawtooth wave.
It is understood that the parameters of the fourth resistor R4, the fifth resistor R5 and the first capacitor C1 will determine the frequency of the sawtooth voltage obtained at the inverting input of the first operational amplifier A1.
As shown in fig. 4, the reference voltage generating circuit 20 generates the reference voltage according to the auxiliary voltage VCC, and specifically, the reference voltage generating circuit 20 includes a sixth resistor R6, a seventh resistor R7, and a second capacitor C2.
The second auxiliary voltage VCC2 is applied to one end of the sixth resistor R6, the other end of the sixth resistor R6, one end of the seventh resistor R7, one end of the second capacitor C2, and the second input terminal 31B (the non-inverting input terminal of the second operational amplifier a 2) of the comparator circuit 31 are connected, and the other end of the seventh resistor R7 and the other end of the second capacitor C2 are grounded.
When the system is powered on, the second auxiliary voltage VCC2 charges the second capacitor C2 from an initial voltage (assuming that the electricity stored in the second capacitor C2 before the system is powered on is discharged through the seventh resistor R7, the initial voltage of the second capacitor C2 is zero voltage) through the sixth resistor R6, and the voltage of the second capacitor C2 gradually rises, so that a voltage that the voltage gradually rises from 0 to the second auxiliary voltage VCC2 is obtained at the non-inverting input terminal of the second operational amplifier a2, and the voltage is the reference voltage.
As shown in fig. 5 to 7, since the inverting input terminal of the second operational amplifier a2 is inputted with the sawtooth wave voltage and the non-inverting input terminal thereof is inputted with the reference voltage, when the reference voltage is smaller than the sawtooth wave voltage, the second operational amplifier a2 always outputs a low level, when the reference voltage starts to be larger than the sawtooth wave voltage, the second operational amplifier a2 outputs a high level whose duty ratio is extremely small, since the reference voltage is a gradually increasing voltage, and thus, in each period thereafter, the time during which the reference voltage is larger than the sawtooth wave voltage becomes gradually longer, and therefore, the duty ratio of the high level outputted by the second operational amplifier a2 also gradually increases, thereby obtaining a pulse voltage whose duty ratio is gradually increased, when the reference voltage is completely larger than the sawtooth wave voltage, the second operational amplifier a2 outputs a high level whose duty ratio is 1, at which the soft start process of the motor is ended, and the motor M is enabled to enter a normal working state to work at a rated power.
It can be understood that the pulse voltage with the duty ratio gradually increased from 0 is suitable for driving the power switch tube controlled to be turned on at the high level, and when the power switch tube controlled to be turned on at the low level is driven, the second operational amplifier a2 may obtain a pulse signal with the duty ratio gradually decreased from 1 according to the reference voltage and the sawtooth wave voltage, so as to achieve the purpose of adjusting the starting power of the motor.
It can be understood that the waveform of the pulse voltage is reliable and stable, the start power of the motor M can be well adjusted by driving and controlling the NMOS transistor Q1 by using the pulse voltage, and the motor M can achieve a good soft start effect when being started.
After the system is powered off, the electricity on the second capacitor C2 is discharged through the seventh resistor R7 until the electricity on the second capacitor C2 is discharged, and the initial voltage of the second capacitor C2 becomes zero voltage, so that the motor M can normally complete soft start when the system is powered on next time.
In order to achieve overvoltage protection between the gate and the source of the NMOS transistor Q1 and avoid damage to the NMOS transistor Q1 due to the gate-source voltage VGS of the NMOS transistor Q1 being too high, in some embodiments, as shown in fig. 4, the soft start circuit 100 further includes a voltage stabilizing circuit 40.
The first terminal of the regulator 40, the gate of the NMOS transistor Q1, and the output terminal 31C of the comparator 31 (the output terminal of the second operational amplifier a 2) are commonly connected, and the second terminal of the regulator 31 is grounded.
Specifically, the stabilizing circuit 40 is a zener diode Z1, a cathode of the zener diode Z1 is a first end of the stabilizing circuit 40, and an anode of the zener diode Z1 is a second end of the stabilizing circuit 40.
In order to limit the current flowing through the NMOS transistor Q1 and prevent the NMOS transistor Q1 from burning out due to excessive current, in some embodiments, as shown in fig. 4, the soft-start circuit 100 further includes a current limiting circuit 50.
One end of the current limiting circuit 50, the first end of the voltage stabilizing circuit 40 (the cathode of the zener diode Z1), and the output terminal 31C of the comparator circuit 31 (the output terminal of the second operational amplifier a 2) are commonly connected, and the other end of the current limiting circuit 50 is connected to the gate of the NMOS transistor Q1.
Specifically, the current limiting circuit 50 is an eighth resistor R8.
In order to discharge the junction capacitance of the NMOS transistor Q1 and avoid the mis-turn on of the NMOS transistor Q1, in some embodiments, as shown in fig. 4, the soft-start circuit 100 further includes a discharge circuit 60.
One end of the discharge circuit 60, one end of the current limiting circuit 50, and the gate of the NMOS transistor Q1 are commonly connected, and the other end of the discharge circuit 60 is grounded.
Specifically, the discharge circuit 60 is a ninth resistor R9.
As another aspect of the embodiment of the present invention, the embodiment of the present invention further provides a motor, including the soft start circuit 100 as described above. The soft start circuit 100 may be directly assembled into the motor for convenient application in a motor without speed regulation.
Finally, it is to be understood that the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, which are intended as additional limitations on the scope of the invention, as these embodiments are provided so that the disclosure will be thorough and complete. In addition, under the idea of the present invention, the above technical features are combined with each other continuously, and many other variations of the present invention in different aspects as described above are considered as the scope of the present invention; further, modifications and variations will occur to those skilled in the art in light of the foregoing description, and it is intended to cover all such modifications and variations as fall within the true spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A soft start circuit, comprising:
the sawtooth wave generating circuit is used for being applied with a first auxiliary voltage and generating sawtooth wave voltage according to the first auxiliary voltage;
a reference voltage generating circuit to which a second auxiliary voltage is applied and which generates a reference voltage according to the second auxiliary voltage, wherein a voltage of the reference voltage is variable;
and the power regulating circuit is respectively connected with the sawtooth wave circuit, the reference voltage generating circuit and the motor and is used for regulating the starting power of the motor according to the sawtooth wave voltage and the reference voltage so as to limit the starting power of the motor and realize the soft start of the motor.
2. The soft-start circuit of claim 1, wherein the power conditioning circuit comprises a comparison circuit and a switching circuit;
the comparison circuit comprises a first input end, a second input end and an output end, the first input end of the comparison circuit is connected with the sawtooth wave generation circuit, the second input end of the comparison circuit is connected with the reference voltage generation circuit, and the comparison circuit obtains a pulse voltage with the duty ratio gradually increased from 0 or gradually decreased from 1 according to the sawtooth wave voltage and the reference voltage and outputs the pulse voltage through the output end of the comparison circuit;
and the switching circuit is respectively connected with the motor, the output end of the comparison circuit and a motor power supply, and adjusts the starting power of the motor according to the pulse voltage and the power supply voltage output by the motor power supply.
3. The soft-start circuit of claim 2, wherein the switch circuit comprises an NMOS transistor and a first diode;
the negative pole of the first diode, the first end of the motor and the power supply of the motor are connected together, the positive pole of the first diode, the second end of the motor and the drain electrode of the NMOS tube are connected together, the grid electrode of the NMOS tube is connected with the output end of the comparison circuit, and the source electrode of the NMOS tube is grounded.
4. The soft start circuit of claim 2, wherein the sawtooth wave generating circuit comprises a first operational amplifier, a second diode, a first capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor;
one end of the first resistor is used for being applied with the first auxiliary voltage, the other end of the first resistor, one end of the second resistor, one end of the third resistor and the non-inverting input end of the first operational amplifier are connected together, the other end of the second resistor is grounded, the other end of the third resistor, the cathode of the second diode and the output end of the first operational amplifier are connected, the anode of the second diode, one end of the fourth resistor and one end of the fifth resistor are connected, the other end of the fourth resistor, one end of the first capacitor, the inverting input end of the first operational amplifier and the first input end of the comparison circuit are connected, the other end of the first capacitor is grounded, and the other end of the fifth resistor is used for being applied with the first auxiliary voltage.
5. The soft-start circuit of claim 2, wherein the reference voltage generating circuit comprises a sixth resistor, a seventh resistor and a second capacitor;
one end of the sixth resistor is used for being applied with the second auxiliary voltage, the other end of the sixth resistor, one end of the seventh resistor, one end of the second capacitor and the second input end of the comparison circuit are connected, and the other end of the seventh resistor and the other end of the second capacitor are grounded.
6. The soft-start circuit of claim 3, further comprising a voltage regulator circuit;
the first end of the voltage stabilizing circuit, the grid electrode of the NMOS tube and the output end of the comparison circuit are connected together, the second end of the voltage stabilizing circuit is grounded, and the voltage stabilizing circuit is used for realizing overvoltage protection between the grid electrode and the source electrode of the NMOS tube.
7. The soft-start circuit of claim 6, further comprising a current limiting circuit;
one end of the current limiting circuit, the first end of the voltage stabilizing circuit and the output end of the comparison circuit are connected together, the other end of the current limiting circuit is connected with the grid electrode of the NMOS tube, and the current limiting circuit is used for limiting the current flowing through the NMOS tube.
8. The soft-start circuit of claim 7, further comprising a discharge circuit;
one end of the discharge circuit, one end of the current limiting circuit and the grid electrode of the NMOS tube are connected together, the other end of the discharge circuit is grounded, and the discharge circuit is used for discharging junction capacitance of the NMOS tube.
9. The soft-start circuit of any one of claims 2 to 8, wherein the comparison circuit comprises a second operational amplifier;
the inverting input end of the second operational amplifier is the first input end of the comparison circuit, the non-inverting input end of the second operational amplifier is the second input end of the comparison circuit, and the output end of the second operational amplifier is the output end of the comparison circuit.
10. An electrical machine comprising a soft start circuit as claimed in any one of claims 1 to 9.
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|---|---|---|---|
| CN202120561174.0U CN215072203U (en) | 2021-03-18 | 2021-03-18 | Soft start circuit and motor |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202120561174.0U CN215072203U (en) | 2021-03-18 | 2021-03-18 | Soft start circuit and motor |
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| CN215072203U true CN215072203U (en) | 2021-12-07 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115514257A (en) * | 2022-10-27 | 2022-12-23 | 北京瀚海科技有限公司 | Novel electric winch is with slowly starting circuit |
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2021
- 2021-03-18 CN CN202120561174.0U patent/CN215072203U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115514257A (en) * | 2022-10-27 | 2022-12-23 | 北京瀚海科技有限公司 | Novel electric winch is with slowly starting circuit |
| CN115514257B (en) * | 2022-10-27 | 2024-03-22 | 北京瀚海科技有限公司 | Slow start circuit for electric winch |
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