CN212343687U - AC electric tool - Google Patents
AC electric tool Download PDFInfo
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- CN212343687U CN212343687U CN202021868158.8U CN202021868158U CN212343687U CN 212343687 U CN212343687 U CN 212343687U CN 202021868158 U CN202021868158 U CN 202021868158U CN 212343687 U CN212343687 U CN 212343687U
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Abstract
An alternating current electric tool comprises an alternating current power supply, a driving module, a motor and a control module for controlling the motor through the driving module; the alternating current power supply comprises a rectifying circuit which rectifies a voltage sinusoidal signal input by the alternating current power supply into a periodic waveform signal; the control module collects the voltage value corresponding to each sampling moment of the periodic waveform signal in a preset sampling time period,performing linear fitting on the voltage value to obtain a slope corresponding to the phase phi of the voltage sinusoidal signal; when the slope is equal to a preset value, the phase phi corresponding to the slope is taken as an initial phase phi0And calculating the phase phi of the voltage sinusoidal signal at any time in the period. The alternating current electric tool can accurately control the motor to operate, and the problems of drive failure, error phase commutation and the like are avoided.
Description
[ technical field ] A method for producing a semiconductor device
The utility model relates to an electric tool technical field, specificly relate to electric tool control field.
[ background of the invention ]
In the alternating current electric tool, an alternating current power supply is connected and supplied with power by the alternating current power supply, usually, it is necessary to obtain the zero crossing point of the ac voltage sinusoidal signal as the starting point of the periodic voltage sinusoidal signal, and obtain the phase corresponding to any time in the period with the starting point as the reference, and the sine value corresponding to the phase, the control module of the ac electric tool takes the phase and the sine value of the phase as important parameters for accurately controlling the brushless motor, however, in the existing conventional control circuit of the ac electric tool, due to the circuit characteristics, there may be a time difference between the zero crossing point detected by the control module and the actual zero crossing point, the zero crossing point with time difference is used as an initial phase, the phase of the obtained voltage sinusoidal signal at any time in the period can deviate, and further the driving of the control module is disabled, and the phase is changed mistakenly.
Accordingly, there is a need for an ac power tool that overcomes the deficiencies of the prior art.
[ Utility model ] content
The utility model aims to prior art's is not enough, the utility model aims to provide an alternating current electric tool, this alternating current electric tool can accurate control motor operation, avoids drive inefficacy and wrong commutation scheduling problem.
The utility model provides a technical scheme that prior art problem adopted is: the alternating current electric tool comprises an alternating current power supply, a driving module, a motor and a control module for controlling the motor through the driving module; the alternating current power supply comprises a rectifying circuit which rectifies a voltage sinusoidal signal input by the alternating current power supply into a periodic waveform signal; the control module acquires voltage values corresponding to each sampling moment of the periodic waveform signal in a preset sampling time period, and performs linear fitting on the voltage values to obtain the slope of the voltage sinusoidal signal; the slope and the phase phi of the voltage sinusoidal signal correspond to each other, and when the control module detects that the slope is equal to a preset value stored in the control module, the phase phi corresponding to the slope is used as an initial phase phi0And calculating the phase phi of the voltage sinusoidal signal at any time in the period.
Preferably, the preset value is set to 0, and when the slope is equal to 0, the corresponding initial phase phi is determined0Is 90 deg..
Preferably, after the control module detects a rising edge of a zero-crossing signal of the voltage sinusoidal signal, a preset time is delayed to start collecting the voltage value corresponding to each sampling time.
Preferably, when the control module detects that the voltage value corresponding to the next sampling time of the periodic waveform signal is greater than the voltage value corresponding to the previous sampling time, and the voltage value is greater than a preset voltage threshold, the control module starts to collect the voltage value corresponding to each sampling time.
Preferably, after the control module detects a rising edge of a zero-crossing signal of the voltage sinusoidal signal, a preset time is delayed, and when it is detected that the voltage value corresponding to the next sampling time of the periodic waveform signal is greater than the voltage value corresponding to the previous sampling time and the voltage value is greater than a preset voltage threshold, the control module starts to collect the voltage value corresponding to each sampling time.
Preferably, the control module calculates the starting phase phi0A sine value corresponding to the phase phi at any time in the period; the control module is used for controlling the starting phase phi according to the starting phase phi0And the phase phi and the sine value at any time in the period are used for controlling the motor through the driving module.
Preferably, the alternating current power supply is electrically connected with an EMC module for filtering electromagnetic interference, and the control module is electrically connected with an output end of the EMC module through a resistor to detect a rising edge of a zero-crossing signal of the voltage sinusoidal signal.
Preferably, the control module includes a logic operation unit, the logic operation unit calculates a slope of the voltage sinusoidal signal by a least square method, and when sampling is performed continuously in the preset sampling period, a formula for calculating the slope is as follows:
in the formula: e (t u) is the mathematical expectation of the product of the sampling instant and the voltage value,
et Eu is the product of the mathematical expectation of the sampling instant and the mathematical expectation of the voltage value,
E(t2) For the mathematical expectation of the square of the sampling instant,
(Et)2 is the mathematically expected square of the sampling instant,
when discrete sampling is performed at equal time intervals within the preset sampling period, the formula for calculating the slope is as follows:
wherein n is the number of sampling points and n is a positive integer greater than 1.
Preferably, the number of sampling points n is 2mAnd m is a positive integer.
Compared with the prior art, the utility model discloses following beneficial effect has: the control module obtains the slope of the periodic waveform signal through linear fitting, and obtains the phase phi corresponding to the slope at the moment when the slope is equal to a preset value because the slope is in one-to-one correspondence with the phase phi of the voltage sinusoidal signal, and the phase phi is taken as an initial phase phi0The control module can calculate the phase phi at any time in the voltage sine signal period, so that the control module can accurately obtain the initial phase phi0And the phase phi of any moment in the period, so that the situation that the phase of any moment in the period has errors when the zero-crossing point detected by the control module is offset and the zero-crossing point is taken as the starting phase is avoided, and the control module uses the detected starting phase phi to detect0And the phase phi at any time in the period is taken as a parameter, so that the motor can be driven to run more accurately, and the problems of phase change error, driving failure and the like are avoided.
[ description of the drawings ]
The following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings:
FIG. 1 is a graph illustrating the drift of a control module when detecting a zero crossing of a sinusoidal voltage signal;
fig. 2 is a schematic circuit diagram of an ac power tool according to an embodiment of the present invention;
FIG. 3 is a graph of a periodic waveform signal linearization in one embodiment of the present invention;
FIG. 4 is a flow chart of an algorithm of a logic unit according to an embodiment of the present invention;
fig. 5 is a flow chart of an algorithm for reducing computational overhead in one embodiment of the present invention.
[ detailed description ] embodiments
The present invention will be described in further detail with reference to the accompanying drawings and embodiments.
Referring to fig. 1, due to circuit characteristics, there is a time difference between an actual zero crossing point of the voltage sinusoidal signal and a detected zero crossing point, if the detected zero crossing point is used as an initial phase, a phase of the voltage sinusoidal signal at any time in a cycle cannot be accurately acquired, and if the zero crossing point is used as the initial phase, a control module may cause problems such as a phase change error and a drive failure.
Fig. 2 shows an ac electric tool according to an embodiment of the present invention, which includes an ac power supply 1, a driving module 4, a motor 6, and a control module 5 for controlling the motor 6 via the driving module 4; the alternating current power supply 1 comprises an EMC module 2 for filtering electromagnetic interference and a rectifying circuit 3, wherein the rectifying circuit 3 rectifies a voltage sinusoidal signal input by the alternating current power supply 1 into a periodic waveform signal; the control module 5 is electrically connected with the rectifying circuit 3 and used for acquiring a voltage value corresponding to each sampling moment of the periodic waveform signal in a preset sampling time period, and performing linear fitting on the voltage value; obtaining the slope of the periodic waveform signal, wherein the slope corresponds to the phase of the periodic waveform signal, and the periodic waveform signal is obtained by rectifying the voltage sinusoidal signal, so that the slope also corresponds to the phase phi of the voltage sinusoidal signal; when the control module 5 detects that the slope is equal to a preset value stored in the control module 5, the phase phi corresponding to the slope is taken as an initial phase phi0And calculating the voltage sine signal in the period TThe phase phi at any time; the control module 5 calculates the starting phase phi0And a sine value corresponding to the phase phi at any time in the period T, wherein the control module 5 is used for controlling the phase phi according to the initial phase phi0The phase phi and the sine value at any time in the period T are used for controlling the motor 6 through the driving module 4. The control module 5 starts with the start phase phi0And the sine value of the phase phi at any time in the period T are used as parameters, so that the driving motor can be more accurately driven to run, and the problems of driving failure, wrong phase change and the like caused by inaccurate zero crossing point detection of the control module 5 are avoided.
The control module 5 is electrically connected with the output end of the EMC module 2 through a resistor R, and detects a zero-crossing signal rising edge of the voltage sinusoidal signal, where the zero-crossing signal rising edge is a time when the voltage sinusoidal signal detected by the control module 5 jumps from a low level to a high level; the control module 5 comprises a logical operation unit 51, wherein the logical operation unit 51 calculates the slope of the voltage sinusoidal signal by a least square method, and when sampling is performed continuously in the preset sampling time period, the formula for calculating the slope is as follows:
where E (t u) is the mathematical expectation of the product of the sampling time t and the voltage value u, Et Eu is the product of the mathematical expectation of the sampling time t and the mathematical expectation of the voltage value u, E (t u)2) Is the mathematical expectation of the square of the sampling instant t, (Et)2 is the square of the mathematical expectation of the sampling instant t. As shown in fig. 4, in order to reduce the calculation overhead of the logic operation unit 51, the calculation process of the logic operation unit 51 is that before the voltage value u is collected, the control module 5 detects a rising edge of the zero-crossing signal of the voltage sinusoidal signal, and after the control module 5 detects the rising edge of the zero-crossing signal of the voltage sinusoidal signal, the control module delays for a preset time Td, and when the next sampling time t of the periodic waveform signal is detected, the sampling time t corresponds to a preset time TdIs greater than the voltage value u corresponding to the last sampling time t, i.e. ui＞ui-1And when the voltage value u is greater than the voltage threshold value Vthr preset by the control module 5, starting to collect the voltage value u corresponding to each sampling time t, and then according to the formula
And calculating the slope k, and when k is 0, obtaining the moment when the phase of the periodic waveform signal is 90 degrees, namely the moment when the phase of the voltage sinusoidal signal is 90 degrees. And when k is greater than 0, continuing to acquire the voltage value u corresponding to the sampling time t, calculating the slope k until the slope k is equal to 0, and when k is less than 0, ending the operation flow of the logic operation unit 51 and detecting the rising edge of the zero-crossing signal again. Taking the 90 DEG phase of the voltage sinusoidal signal as the starting phase phi0In the meantime, the preset time Td is delayed after the rising edge of the zero-crossing signal passes, and the acquisition calculation is performed when the voltage value u is greater than the voltage threshold Vthr, so that a large amount of invalid calculations can be avoided, and the calculation overhead of the logic operation unit 51 is reduced.
In order to further reduce the calculation overhead of the logic operation unit 51, discrete sampling is performed at equal time intervals Δ t within the preset sampling time period, and the periodic waveform signal is acquired within the preset time period at the sampling time t0，t1，t2，……，tiCorresponding voltage value u0，u1，u2，……，uiI is the number of sampling points; sampling time interval Δ ti＝ti+1-tiEach of said sampling time intervals Δ tiEqual, the voltage value u is discrete as a collection sample. In discrete sampling, the formula for calculating the slope is as follows:
wherein n is a positive integer greater than 1, wherein i is 0,1,2, … … n-1,
n number of sampling points, the accumulation of the product of ti and ui,
n number of sample points, the product of the accumulation of ti and the accumulation of ui,
for n sample points, the sum of the squares of ti,
for n sampling points, the square of the sum of ti, and to further reduce the computation overhead of the logical operation unit 51, a positive integer n may be set to 2mM is a positive integer, when k is 0, the control module 5 obtains the time when the phases of the periodic waveform signal and the voltage sinusoidal signal are 90 °, and takes the phase of 90 ° as a starting phase phi0And acquiring the phase phi of the voltage sinusoidal signal at any time in the period T.
The present invention is not limited to the above-described embodiments. It will be readily appreciated by those skilled in the art that many alternatives to the ac power tool may be made without departing from the spirit and scope of the invention. The protection scope of the present invention is subject to the content of the claims.
Claims (9)
1. An alternating current electric tool comprises an alternating current power supply, a driving module, a motor and a control module for controlling the motor through the driving module; the method is characterized in that: the alternating current power supply comprises a rectifying circuit which rectifies a voltage sinusoidal signal input by the alternating current power supply into a periodic waveform signal; the control module acquires voltage values corresponding to each sampling moment of the periodic waveform signal in a preset sampling time period, and performs linear fitting on the voltage values to obtain the slope of the voltage sinusoidal signal; the slope and the phase phi of the voltage sinusoidal signal correspond to each otherWhen the control module detects that the slope is equal to a preset value stored in the control module, the phase phi corresponding to the slope is taken as an initial phase phi0And calculating the phase phi of the voltage sinusoidal signal at any time in the period.
2. The ac power tool of claim 1, wherein: the preset value is set to be 0, and when the slope is equal to 0, the corresponding initial phase phi is obtained0Is 90 deg..
3. The ac power tool of claim 2, wherein: and after the control module detects the rising edge of the zero-crossing signal of the voltage sinusoidal signal, delaying preset time to start collecting the voltage value corresponding to each sampling moment.
4. The ac power tool of claim 2, wherein: the control module detects that the voltage value corresponding to the next sampling time of the periodic waveform signal is greater than the voltage value corresponding to the last sampling time, and starts to collect the voltage value corresponding to each sampling time when the voltage value is greater than a preset voltage threshold value.
5. The ac power tool of claim 2, wherein: and after the control module detects the rising edge of the zero-crossing signal of the voltage sinusoidal signal, delaying preset time, and when the control module detects that the voltage value corresponding to the next sampling time of the periodic waveform signal is greater than the voltage value corresponding to the last sampling time and the voltage value is greater than a preset voltage threshold value, starting to acquire the voltage value corresponding to each sampling time.
6. An AC power tool as claimed in any one of claims 1 to 5, wherein: the control module calculates the starting phase phi0Sine corresponding to the phase phi at any time in the periodA value; the control module is used for controlling the starting phase phi according to the starting phase phi0And the phase phi and the sine value at any time in the period are used for controlling the motor through the driving module.
7. An AC power tool as claimed in any one of claims 1 to 5, wherein: alternating current power supply electric connection has filtering electromagnetic interference's EMC module, control module passes through resistance electric connection the output of EMC module detects voltage sinusoidal signal's zero passage signal rising edge.
8. An AC power tool as claimed in any one of claims 1 to 5, wherein: the control module comprises a logic operation unit, the logic operation unit calculates the slope of the voltage sinusoidal signal through a least square method, and when continuous sampling is carried out in the preset sampling time period, the formula for calculating the slope is as follows:
in the formula: e (t u) is the mathematical expectation of the product of the sampling instant and the voltage value,
et Eu is the product of the mathematical expectation of the sampling instant and the mathematical expectation of the voltage value,
E(t2) For the mathematical expectation of the square of the sampling instant,
(Et)2for the mathematically expected square of the sampling instant,
when discrete sampling is performed at equal time intervals within the preset sampling period, the formula for calculating the slope is as follows:
wherein n is the number of sampling points and n is a positive integer greater than 1.
9. The ac power tool of claim 8, wherein: the number of sampling points n is 2mAnd m is a positive integer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021868158.8U CN212343687U (en) | 2020-08-31 | 2020-08-31 | AC electric tool |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021868158.8U CN212343687U (en) | 2020-08-31 | 2020-08-31 | AC electric tool |
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| CN212343687U true CN212343687U (en) | 2021-01-12 |
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| CN202021868158.8U Active CN212343687U (en) | 2020-08-31 | 2020-08-31 | AC electric tool |
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