Introduction
In recent years, along with the electric power
electronic device and the control theory rapid development, permanent
magnetism direct current not brushed the electrical machinery by its
effectiveness, the good velocity modulation, the easy maintenance to
obtain the widespread application. Traditional permanent
magnetism direct current not brushes the electrical machinery often to
use the position transducer to determine the rotor the position, this
not only increased the electrical machinery to install the volume,
increased the cost, moreover reduced the electrical machinery
reliability. At present, non- sensor direct current not brushes
the electrical machinery generally to select the triadic starting
method, the starting moment when starts the starting quite is small,
and has the pulsation, regarding has the starting moment request the
system to have the limitation, but bends down in the water pump system
in the middle and small scale solar energy light, the load moment is,
does not count the friction force which increases along with the
rotational speed increase, in the static time load moment is zero,
therefore, direct current not brushes the electrical machinery to be
allowed to be supposed to use in the light to bend down the water pump
system, and the overall system is direct current, does not need to
invert, then, bends down in the water pump system in the light
application direct current not to brush the electrical machinery,
regarding enhances the system efficiency, The simplification
system installment has the significant significance.
1 light bends down the water pump system synopsis
The light bends down the water pump system to bend down
the array by the light, the controller, the electrical machinery, the
water pump 4 parts is composed. The light bends down the array
by many solar cell series-parallel connection constitution, directly
transforms the solar energy as the direct current electrical energy.
At present uses solar cell all for silicon solar cell, including
monocrystalline silicon, polycrystalline silicon and crystalless
silicon solar cell. Because the light bends down the array to
lose the end of summer dog days - Anter curve to have the intense
non-linearity, moreover with the solar irradiance, the ambient
temperature, cloudy, is clear, meteorological condition and so on
rain, fog has the close relation, therefore, if must cause the light
to bend down the water pump system work in the quite ideal operating
mode, needs to use the controller to adjust, the control overall
system. The electrical machinery is uses for to actuate the
water pump, because the electrical machinery power factor and the
voltage rank receive solar cell array in the very great degree the
voltage rank and the power rank restriction, therefore, to lift of
pump, the current capacity request was reflected to the electrical
machinery on, often specially carries on the design in under the
proper attention to both array structure condition. Is small
regarding the request current capacity, lifts the high user, suitably
selects the volume type water pump; Regarding needs the current
capacity to be bigger, but lifts actually a lower user, general
suitably uses 自吸 the type water pump.
2 monolithic integrated circuits
M68HC908JK3ECP introduction
This is in Motorola Corporation's one of 8 monolithic
integrated circuits families' members, similarly has the high
performance, low cost merit. In it inlays 4k to dodge fast
memory FLASH, 128 byte RAM; Has 10 channels 8 precisions ADC
modules, 15 I/O port; The clock module has the input capture,
function and so on output comparison and pulse-duration modulation,
can satisfy the system request.
3 non- sensors direct current not brush the
electrical machinery control principle
Not brushes the electrical machinery the stator for the
three-phase symmetrical winding, uses two electrifies when the way the
control circuit according to the certain order to the stator two to
pass over the direct current, produces stator magnetic potential Fa;
The rotor is the permanent-magnet material, produces magnetic
potential Ff, through two mutual functions, may produce
electromagnetism torque T=FaFf|sin theta |, obviously, when theta
=60° ~ 120°, the average electromagnetism torque is biggest.
When examination rotor magnetic potential position, when decides
the rotor magnetic potential included angle for 60°, in the
three-phase winding some two leads passes, when has transferred 60°,
power tube shuts off, another center power tube leads passes.
Thus, guaranteed decides the rotor magnetic potential included
angle for 60° ~ 120°, achieves the torque biggest goal.
Because each time transfers 60° has only shut off a power tube,
therefore each power tube leads passes the angle for 120°, this way
for 120° leads passes the way.
The main circuit uses three-phase all controls the bridge, like
chart 1 shows. Chart 2 is under the three-phase 6 rackets work
way the typical phase voltage counter electromotive force oscillogram.
We may clearly see from chart 2, when this hanging condition (a
zero around 30° region) under, the winding has induced the counter
electromotive force according to the sine rule change, the flat top
department divides into the winding circular telegram drive inverts
换相 the main circuit voltage clamp to cause. 换相 the spot
occurs after zero 30°, the use counter electromotive force law
realizes the electron 换相, is has had been to zero after the zero
examination electric circuit examination 30° to carry on 换相.
Under the three-phase 6 rackets work way, leads passes the order
is S1, S2 - S2, S3 - S3, S4 - S4, S5 - S5, S6 - S6, S1 - S1, S2.
Has many kinds of based on the counter electromotive force
electronic 换相 method, like "1/2 generatrix voltage comparison
test", "terminal voltage comparison test" and so on, but these
measuring techniques all have the antijamming ability weak problem,
specially when PWM modulation situation, survey must take the special
measure to avoid or the suppression disturbance, increased the control
circuit complexity, and possibly has 换相 the lag. May solve
the problem above using "the hypothesized center point law", and in
the PWM modulation situation, its switch noise cannot affect 相绕?the zero survey, examines the electric circuit to be also simpler.
The counter electromotive force value is 0 or is very
small under static either the low speed condition, is unable to
determine the rotor with the counter electromotive force law the
position, usually selects the triadic starting method to solve this
problem, namely first controls the type synchronous machine according
to him the running status from static to start to accelerate, when
achieved when certain rotational speed again cuts the counter
electromotive force law control condition, locates including the
rotor, step enters the starting and freely cuts three stages.
The rotor locates when the first forerunner passes two power
tubes, generally speaking the forerunner passes S6 and S1, after the
certain time completes the rotor the initial localization. Step
enters when the starting starts from the initial point, leads
according to front passes the order to lead in turn passes various
power tubes, but leads passes the time to decrease progressively
according to the certain rule, achieved raises the fast goal.
After step enters the starting to finish carries on the free
cut, guaranteed 换相 the accuracy, simultaneously, PWM cuts the wave
to make the direct current side voltage gradually to add to on the
main circuit, causes not to brush the electrical machinery the
rotational speed according to the control request acceleration, is
equal to the electrical machinery rotational speed 软起?the
process, like this avoided the electrical machinery being able to
produce the big electric current in the starting initial period,
reduced to the main circuit the impact, lengthened the power tube
life.
4 systems realizations
The system hardware electric circuit by the main
circuit, actuates the electric circuit, the zero examination electric
circuit, the sampling electric circuit, each kind of protection
circuit to be composed. Crosses the zero examination electric
circuit examination to have been to the zero signal, and has delivered
the zero signal the JK3 monolithic integrated circuit the capture
mouth, the JK3 monolithic integrated circuit receive has been to the
zero signal, calculates the delay time based on software, and sends
out 换相 the pulse signal in the delay time to after, after actuates
the electric circuit to transform for the driving signal actuates
various power tubes, like this realized the monolithic integrated
circuit not to brush the electrical machinery to direct current the
control. The protection circuit mainly has 过电?the charge
protection, the low water level protection.
The system software uses the modular design, including
initialization module, PWM severance module, capture severance module,
sampling protection module. The PWM severance module realized
has not brushed the electrical machinery step to enter the starting,
the freedom cuts the movement. PWM severance module flow chart
like chart 3 shows.
The initialization module mainly completes the procedure to use
the variable the initialization, the PWM severance initialization, the
capture severance initialization, sends the initial localization
pulse; The capture severance completes a counter electromotive
force zero capture and 换相 the cyclical determination; The
sampling protection module mainly uses for to gather the direct
current side voltage and the electric current, as well as
determination and processing breakdown. The empirical datum
proved that, 换相 the time accuracy and the phase track rapidity the
performance influence which controls to the electrical machinery is
enormous, electronic switching accurate 换相 each time all after
this exciting winding counter electromotive force zero 30° 电角?
position, because the electrical machinery movement is changes speed
the movement, 换相 the cycle is the change, therefore certainly
cannot accurately determine retards 30° 电角?front 换相 the
time, only can act according to certain 换相 cyclical change
tendency, carries on the reasonable effective filter and the estimate
to this 换相 time, has the digital filter and the phase-lock tracks
two ways.
Chart 4 is when the system normal operation obtains the
line voltage waveform, the burr part is cuts the wave by PWM and
换相 causes. May see from the chart, the voltage waveform
quite close to the ideal situation, shows 换相 accurate, thus has
confirmed to the overall system control thought is correct.
5 conclusions
The above thought already bent down in the 500W solar
energy light in the water pump system to obtain the confirmation.
When system starting the initial firing current is normal, after
step enters the starting to finish accelerates steadily.
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