CN115562429A - Power control method - Google Patents

Power control method Download PDF

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CN115562429A
CN115562429A CN202211246808.9A CN202211246808A CN115562429A CN 115562429 A CN115562429 A CN 115562429A CN 202211246808 A CN202211246808 A CN 202211246808A CN 115562429 A CN115562429 A CN 115562429A
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pwm wave
zero
module
pwm
crossing
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王德业
姜其超
贾鹏飞
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Shenzhen Pinluo Innovation Industrial Co ltd
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Shenzhen Pinluo Innovation Industrial Co ltd
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/66—Regulating electric power

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Abstract

The invention discloses a power control method which comprises a zero-crossing detection module, an MCU control module, a silicon controlled module and a storage module. The zero-crossing detection module detects the zero-crossing point of the alternating current power supply and transmits high and low level signals to the MCU control module; the MCU control module obtains a zero-crossing frequency according to the zero-crossing detection module; the MCU control module obtains a PWM wave duty ratio value according to a PWM wave duty ratio calculation method, and stores the power ratio of the electric appliance and the PWM wave duty ratio value into a storage module; the MCU control module reads out the duty ratio value and the frequency of the PWM wave from the storage module, configures the PWM wave and outputs high and low levels to the silicon controlled module according to the PWM wave control method. According to the invention, the MCU control module controls the opening and closing angle of the silicon controlled rectifier in a PWM wave mode, so that the occupation of processor resources is low; the alternating current power supply frequency is obtained through the zero-crossing detection module, and the PWM wave period is adjusted according to the alternating current power supply frequency, so that the control is more reliable, the power control cost is lower, and the precision is higher.

Description

Power control method
Technical Field
The invention belongs to the technical field of silicon controlled rectifier power control, and particularly relates to a power control method.
Background
At present, the common control modes of electric appliances such as alternating current series motors, induction cookers and the like mostly adopt a software/hardware timer of an MCU (microprogrammed control Unit) to carry out time delay to control the opening and closing angle of a controllable silicon so as to achieve the purpose of controlling the power of the electric appliances.
At present, power control is carried out on electric appliances by adopting a time delay method of silicon controlled rectifier and MCU (microprogrammed control Unit), for example, domestic power grid 220V 50Hz alternating current, 100 zero crossing points can be generated every second, and 100 control periods (T) are provided corresponding to the silicon controlled rectifier. And after the MCU delays the time of t1 in 1 control period, a high level is applied to the controlled silicon, the controlled silicon is switched on, the electric appliance works, a low level is applied to the controlled silicon after the MCU delays the time of t2, the controlled silicon is switched off when the electric appliance stops working after the controlled silicon is switched off when the zero crossing point is next time. Therefore, the MCU processor needs to be occupied for 2 times of timer resources in each control period, the timer occupies 200 times per second, the performance requirement on the MCU is high, and if the low-cost low-performance MCU is adopted, the problems of inaccurate timing caused by large data processing capacity of the MCU, abnormal control of the electrical appliance and the like are easily caused. If a high performance MCU is used, more cost is required.
If the controlled silicon is directly controlled by adopting the PWM mode, the zero-crossing period is not stable due to the fluctuation of the power grid frequency, the PWM wave is difficult to be matched with the zero-crossing period, and the abnormal control of the electric appliance is easily caused.
Therefore, the power control method is provided, the controllable silicon is controlled in a mode of variable PWM (pulse-width modulation) period, the zero-crossing period is periodically detected, the PWM wave control period is calibrated, the PWM wave is accurately matched with the zero-crossing period, the controllable silicon is controlled at low cost and high precision, and the power of an electric appliance is further adjusted.
Disclosure of Invention
The invention aims to provide a power control method, and aims to solve the problems of high cost, instability and the like of the existing silicon controlled control method in the background technology. In order to realize the purpose, the invention adopts the technical scheme that:
a power control method comprises a zero-crossing detection module, an MCU control module, a silicon controlled module and a storage module. The zero-crossing detection module detects the zero-crossing point of the alternating current power supply and transmits high and low level signals to the MCU control module;
the MCU control module obtains the zero-crossing frequency f according to the zero-crossing detection module, and the PWM wave frequency is f' = f +1;
setting the power ratio p of the electric appliance, wherein p is between 0 and 100 percent, obtaining a PWM (pulse-width modulation) wave duty ratio value D by the MCU control module according to a PWM wave duty ratio calculation method, and storing the power ratio p of the electric appliance and the PWM wave duty ratio value D into a storage module;
the MCU control module reads out the PWM wave duty ratio value D, PWM wave frequency f' from the storage module, configures PWM waves and then outputs high and low levels to the silicon controlled module according to a PWM wave control method;
the silicon controlled module is correspondingly opened and closed according to the high and low levels output by the MCU control module, so that the current is changed, and the power is further changed.
Further describing the above scheme, wherein the PWM wave duty ratio calculation method comprises: if N zero-crossing periods are a control period, the relationship between the duty ratio value D of the PWM wave and the power ratio p can be calculated by the following formula:
Figure BDA0003887013380000021
further describing the above scheme, the PWM wave frequency is calculated by: acquiring t of time required by passing through m continuous zero-crossing signals, and taking t
Figure BDA0003887013380000022
In order to zero-cross the cycle time,
Figure BDA0003887013380000023
as the zero-crossing frequency, the PWM wave frequency f' = f +1, and the PWM wave period time is slightly less than the zero-crossing period time in order to ensure that a complete PWM wave can exist in a zero-crossing period.
Further describing the above scheme, the PWM wave control method uses N zero-crossing periods as a PWM wave control period, which includes N PWM waves, to control the thyristor module, and includes the following steps:
firstly, detecting a PWM wave duty ratio value D, PWM wave frequency f', if the PWM wave duty ratio value D, PWM wave frequency is changed, reconfiguring the PWM wave, and if the PWM wave duty ratio value D, PWM wave frequency is not changed, not reconfiguring;
secondly, the MCU control module immediately starts PWM waves to output high level when detecting that the 1 st zero-crossing period starts, and immediately starts the first PWM wave to output to the silicon controlled module;
and thirdly, when the MCU control module detects the start of the Nth zero-crossing period, stopping PWM wave output, setting a PWM output port at a low level, and closing the silicon controlled module.
Optionally, the PWM wave duty ratio calculation method may be further replaced by the following method: taking f' = f, the calculation formula of the PWM wave duty value D and the power ratio p is:
Figure BDA0003887013380000031
more preferably, the result of the PWM wave duty ratio value D corresponding to the power ratio p is input into the storage module in advance for storage, and in the power regulation process, the MCU control module does not need to perform complex operation, and directly takes out the PWM wave duty ratio value D from the storage module, so that the MCU control module has low resource occupation and high response speed.
Compared with the prior art, the invention has the following beneficial effects:
1. the MCU control module controls the opening and closing angle of the controllable silicon in a PWM wave mode, so that the occupation of processor resources is low;
2. the alternating current power supply frequency is obtained through the zero-crossing detection module, and the PWM wave period is adjusted according to the alternating current power supply frequency, so that the control is more reliable, the power control cost is lower, and the precision is higher;
3. the MCU control module controls the duty ratio of the PWM wave to control the power of the motor, so that the soft start of the motor can be realized, and the shaking caused by overhigh instantaneous power of the motor is avoided.
Drawings
FIG. 1 is a schematic block diagram of an embodiment of the present invention;
FIG. 2 is a schematic diagram of a PWM wave control signal according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a PWM wave control method according to an embodiment of the present invention;
fig. 4 is a schematic view of a work flow provided in the embodiment of the present invention.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
The technical solution of the present patent will be described in further detail with reference to the following embodiments.
As shown in fig. 1 to 4, a power control method includes a zero-crossing detection module, an MCU control module, a thyristor module, and a storage module. The zero-crossing detection module is used for detecting the zero-crossing point of the alternating-current power supply and transmitting the high-low level signal to the MCU control module; the MCU control module obtains a zero-crossing frequency f according to high and low level signals sent by the zero-crossing detection module, and the PWM wave frequency is f' = f +1; a user sets the power ratio p of an electric appliance, wherein p is between 0 and 100 percent, the MCU control module obtains a PWM wave duty ratio value D according to a PWM wave duty ratio calculation method, and stores the power ratio p of the electric appliance and the PWM wave duty ratio value D into a storage module; the MCU control module reads out the PWM wave duty ratio value D, PWM wave frequency f' from the storage module, configures PWM waves and then outputs high and low levels to the silicon controlled module according to a PWM wave control method; the silicon controlled module is correspondingly opened and closed according to the high and low levels output by the MCU control module, so that the current is changed, and the power is further changed.
The PWM wave duty ratio calculation method comprises the following steps: if N zero-crossing periods are a control period, the relationship between the duty ratio value D of the PWM wave and the power ratio p can be calculated by the following formula:
Figure BDA0003887013380000041
the PWM wave duty ratio calculation method may be further replaced with the following method: taking f' = f, the calculation formula of the PWM wave duty value D and the power ratio p is:
Figure BDA0003887013380000042
certainly, in order to save the operation resources of the MCU control module and accelerate the response time, the result of the PWM wave duty ratio value D corresponding to the power ratio p is input to the storage module in advance for storage, and in the power adjustment process, the MCU control module directly takes out the PWM wave duty ratio value D from the storage module without performing complex operation, and if the power ratio p =0, the PWM wave duty ratio value D =0%; when the power ratio p =0.1, the PWM wave duty value D =20; when the power ratio p =0.2, the PWM duty ratio D =29%, and so on, the MCU control module is low in resource occupation and fast in response speed.
The calculation method of the PWM wave frequency comprises the following steps: acquiring t of time required by passing through m continuous zero-crossing signals, and taking t
Figure BDA0003887013380000043
In order to zero-cross the cycle time,
Figure BDA0003887013380000044
as the zero-crossing frequency, the PWM wave frequency f' = f +1, and the PWM wave period time is slightly less than the zero-crossing period time in order to ensure that a complete PWM wave can exist in a zero-crossing period.
As shown in fig. 3, the PWM wave control method uses N zero-crossing periods as a PWM wave control period, which includes N PWM waves, to control the thyristor module, and includes the following steps:
firstly, detecting a PWM wave duty ratio value D, PWM wave frequency f', if the PWM wave duty ratio value D, PWM wave frequency changes, reconfiguring the PWM waves, and if the PWM wave duty ratio value D, PWM wave frequency does not change, reconfiguring the PWM waves;
secondly, the MCU control module immediately starts PWM (pulse-width modulation) wave output high level when detecting that the 1 st zero-crossing period starts, and immediately starts outputting the first PWM wave to the silicon controlled module at the moment;
and thirdly, when the MCU control module detects the start of the Nth zero-crossing period, stopping PWM wave output, setting a PWM output port at a low level, and closing the silicon controlled module.
The PWM wave control method is explained as shown in fig. 2: setting N =5, taking each 5 zero-crossing periods as a control period, starting PWM wave output (namely, the 1 st PWM wave starts to be output) when the 1 st zero-crossing period starts, stopping the PWM wave output when the 5 th zero-crossing period starts, starting the output of the 5 th PWM wave before the 5 th zero-crossing period starts because the PWM wave period time is slightly less than the zero-crossing period time, stopping the output of the PWM wave after the 5 th PWM wave is output, and setting a PWM wave output port at a low level. Therefore, PWM waves are output in the 5 zero-crossing periods, and the starting and stopping operations of the PWM waves are only carried out in the 1 st and 5 th zero-crossing periods, if the frequency is calculated according to the domestic alternating current 50Hz, the MCU only operates 40 times per second, compared with a software and hardware timer method that the delay operation is carried out 200 times per second, the MCU saves the resource occupation by 4/5, and the workload of the MCU is greatly reduced.
In actual use, for example, an alternating current motor is controlled:
the method comprises the following steps that firstly, a zero-crossing detection module detects the zero-crossing point of an alternating current power supply, high and low level signals are transmitted to an MCU control module, the MCU control module obtains zero-crossing frequency f according to the high and low level signals sent by the zero-crossing detection module, and the PWM wave frequency is f' = f +1;
secondly, setting a power ratio p of the motor by a user, obtaining a duty ratio according to a PWM wave duty ratio calculation method, and storing the power ratio of the motor and the duty ratio value of the PWM wave into a storage module;
and thirdly, obtaining the PWM wave frequency according to a PWM wave frequency calculation method, and storing the PWM wave frequency in a storage module.
And fourthly, the MCU control module reads out the duty ratio and the frequency of the PWM wave from the storage module, configures the PWM wave, and then starts and stops the PWM wave according to the control rule.
And fifthly, the silicon controlled module is correspondingly opened and closed according to the high and low levels output by the MCU control module, the current is changed, and the power of the motor is changed due to the change of the current.
When the motor starts, a soft start method is adopted, the duty ratio D1 corresponding to the initial power, the duty ratio D2 corresponding to the target power and the soft start time t seconds are assumed, namely the set duty ratio is increased from D1 to D2 within t seconds. The duty ratio value to be added per PWM wave control period is Δ D:
Figure BDA0003887013380000061
in conclusion, the invention controls the opening and closing angle of the controllable silicon by the MCU control module in a PWM wave mode, and occupies low processor resources; the alternating current power supply frequency is obtained through the zero-crossing detection module, and the PWM wave period is adjusted according to the alternating current power supply frequency, so that the control is more reliable, the power control cost is lower, and the precision is higher; the MCU control module controls the duty ratio of the PWM wave to control the power of the motor, so that the soft start of the motor can be realized, and the shaking caused by overhigh instantaneous power of the motor is avoided.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. 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 also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. As used herein, the terms "vertical," "horizontal," "left," "right," and the like are for illustrative purposes only and do not represent the only embodiments, and as used herein, the terms "upper," "lower," "left," "right," "front," "rear," and the like are used in a positional relationship with reference to the drawings.
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 herein in the description of the invention 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.
The above embodiments are only for illustrating the invention and are not to be construed as limiting the invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention, therefore, all equivalent technical solutions also belong to the scope of the invention, and the scope of the invention is defined by the claims.

Claims (6)

1. A power control method comprises a zero-crossing detection module, an MCU control module, a silicon controlled module and a storage module, and is characterized in that:
the zero-crossing detection module detects the zero crossing point of the alternating current power supply and transmits high and low level signals to the MCU control module;
the MCU control module obtains a zero-crossing frequency f according to the high-low level signal of the zero-crossing detection module, and the PWM wave frequency is f' = f +1;
setting the power ratio p of the electric appliance, obtaining a PWM (pulse-width modulation) wave duty ratio value D by the MCU (microprogrammed control unit) control module according to a PWM wave duty ratio calculation method, and storing the power ratio p of the electric appliance and the PWM wave duty ratio value D into a storage module;
the MCU control module reads out the PWM wave duty ratio value D, PWM wave frequency f' from the storage module, configures PWM waves and then outputs high and low levels to the silicon controlled module according to a PWM wave control method;
the silicon controlled module is correspondingly opened and closed according to the high and low levels output by the MCU control module.
2. A power control method according to claim 1, characterized in that: the PWM wave duty ratio calculation method comprises the following steps: if N zero-crossing periods are a control period, the relationship between the duty ratio value D of the PWM wave and the power ratio p can be calculated by the following formula:
Figure FDA0003887013370000011
3. a power control method according to claim 1, characterized in that: the calculation method of the PWM wave frequency comprises the following steps: acquiring t of time required by passing through m continuous zero-crossing signals, and taking t
Figure FDA0003887013370000012
In order to zero-cross the cycle time,
Figure FDA0003887013370000013
as the zero-crossing frequency, the PWM wave frequency f' = f +1, and the PWM wave period time is less than the zero-crossing period time.
4. A power control method according to claim 1, characterized in that: the PWM wave control method takes N zero-crossing periods as a PWM wave control period, wherein the PWM wave control period comprises N PWM waves, and the method controls the silicon controlled module and comprises the following steps:
firstly, detecting a PWM wave duty ratio value D, PWM wave frequency f', if the PWM wave duty ratio value D, PWM wave frequency changes, reconfiguring the PWM waves, and if the PWM wave duty ratio value D, PWM wave frequency does not change, reconfiguring the PWM waves;
secondly, the MCU control module immediately starts PWM waves to output high level when detecting that the 1 st zero-crossing period starts, and immediately starts the first PWM wave to output to the silicon controlled module;
and thirdly, when the MCU control module detects the start of the Nth zero-crossing period, stopping PWM wave output, setting a PWM output port at a low level, and closing the silicon controlled module.
5. A power control method according to claim 2, characterized in that: the PWM wave duty ratio calculation method may be further replaced with the following method: taking f' = f, the calculation formula of the PWM duty value D and the power ratio p is:
Figure FDA0003887013370000021
6. a power control method according to claim 2 or 5, characterized by: and inputting the result of the PWM wave duty ratio value D corresponding to the power ratio p into a storage module in advance for storage.
CN202211246808.9A 2022-10-12 2022-10-12 Power control method Pending CN115562429A (en)

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Application Number Priority Date Filing Date Title
CN202211246808.9A CN115562429A (en) 2022-10-12 2022-10-12 Power control method

Publications (1)

Publication Number Publication Date
CN115562429A true CN115562429A (en) 2023-01-03

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